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Secretory leukocyte protease inhibitor (SLPI) is an important cationic protein involved in innate airway immunity and highly expressed in mucosal secretions, shown to target and inhibit neutrophil elastase (NE), cathepsin G and trypsin activity to limit proteolytic activity. In addition to the potent anti-protease activity, SLPI has been demonstrated to exert a direct anti-inflammatory effect, which is mediated via increased inhibition and competitive binding of NF-κB, regulating immune responses through limiting transcription of pro-inflammatory gene targets. In muco-obstructive lung disorders, such as Chronic Obstructive Pulmonary Disease (COPD) and Cystic Fibrosis (CF), there is an observed elevation in airway SLPI protein concentrations as a result of increased lung inflammation and disease progression. However, studies have identified COPD patients presenting with diminished SLPI concentrations. Furthermore, there is a decrease in SLPI concentrations through cleavage and subsequent inactivation by NE degradation in Pseudomonas aeruginosa infected people with CF (pwCF). These observations suggest reduced SLPI protein levels may contribute to the compromising of airway immunity indicating a potential role of decreased SLPI levels in the pathogenesis of muco-obstructive lung disease. The Beta Epithelial Na+ Channel transgenic (ENaC-Tg) mouse model phenotype exhibits characteristics which replicate the pathological features observed in conditions such as COPD and CF, including mucus accumulation, alterations in airway morphology and increased pulmonary inflammation. To evaluate the effect of SLPI in muco-obstructive pulmonary disease, ENaC-Tg mice were crossed with SLPI knock-out (SLPI -/- ) mice, generating a ENaC-Tg/SLPI -/- colony to further investigate the role of SLPI in chronic lung disease and determine the effect of its ablation on disease pathogenesis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Brown, Dougan, Ferris, Delaney, Houston, Rodgers, Downey, Mall, Connolly, Small, Weldon and Taggart.)

Acute myeloid leukaemia (AML) is a severe haematological neoplasm that originates from the transformation of haematopoietic stem cells (HSCs) into leukaemic stem cells (LSCs). The bone marrow (BM) microenvironment, particularly that of mesenchymal stromal cells (hMSCs), plays a crucial role in the maintenance of HSCs. In this context, we explored whether alterations in the secretome of hMSCs derived from AML patients (hMSC-AML) could impact HSC gene expression. Proteomic analysis revealed that the secretome of coculture assays with hMSC-AMLs and HSC from healthy donor is altered, with increased levels of secretory leukocyte protease inhibitor (SLPI), a protein associated with important processes for maintenance of the haematopoietic niche that has already been described to be altered in several tumours. Increased SLPI expression was also observed in the BM plasma of AML patients. Transcriptome analysis of HSCs cocultured with hMSC-AML in comparison with HSCs cocultured with hMSC-HD revealed altered expression of SLPI target genes associated with the cell cycle, proliferation, and apoptosis. Important changes were identified, such as increased expression levels of CCNA2, CCNE2, CCND2, CD133 and CDK1 and decreased levels of CDKN2A and IGFBP3, among others. Overall, these findings suggest that the altered secretome of coculture assays with hMSC-AMLs and HSC from healthy donor, particularly increased SLPI expression, can contribute to gene expression changes in HSCs, potentially influencing important molecular mechanisms related to AML development and progression., (© 2024. The Author(s).)

The secretory leukocyte protease inhibitor (SLPI) is mainly produced by immune cells and various epithelial cells, and is regulated by a variety of cytokines, such as transforming growth factor β1, interleukin 1β and tumor necrosis factor α. In addition to commonly known anti-protease activity, it has been found in recent years that SLPI plays essential roles in anti-apoptosis, regulating cell cycle, cell differentiation and proliferation, and inhibiting inflammatory response. SLPI can also assist the immune system to clear pathogens/damaged cells by enhancing the phagocytic function of phagocytes, so as to ameliorate tissue damage and promote repair. Moreover, recent studies have shown that the change of SLPI level in the serum of patients post cardiovascular surgery has a high diagnostic value in predicting the occurrence of acute kidney injury, suggesting that SLPI is involved in ischemia-reperfusion (IR) induced acute kidney injury. In this review, we summarized the expression, regulation, signaling pathways and associated biological events of SLPI in different organ injury models, and also discussed and evaluated the potential role of SLPI in renoprotection against IR induced acute kidney injury and its potential as a new biomarker.

Objective: Isorhamnetin (IH) has been reported to have significant anti-inflammatory effects in various diseases, but its role and mechanism in AKI remain unclear. This study aimed to explore the potential role and mechanism of isorhamnetin in inhibiting macrophage related inflammation and improving AKI injury., Methods: We established an AKI mouse model by intraperitoneal injection of cisplatin in vivo , and constructed an inflammatory cell model by stimulating RAW264.7 cells with LPS. Creatinine and urea nitrogen were measured to evaluate the changes of renal function in AKI mice. The changes of renal pathological structure were observed by H&E staining. The inflammatory factor-related proteins and RNA expression levels were detected by Western blot and real time PCR., Results: Isorhamnetin protected the kidney from cisplatin induced AKI and significantly inhibited the mRNA and protein levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α) both in AKI kidney and LPS-stimulated RAW264.7 cells. Interestingly, the data also demonstrated that isorhamnetin significantly upregulated the expression of secretory leukocyte peptidase inhibitor (SLPI), an anti-inflammatory factor, in AKI kidney and LPS-stimulated macrophages, as well as inhibited the M1 macrophage and activated M2 macrophage in vitro . Blocking of SLPI by siRNA activated Mincle-associated inflammatory signaling in macrophages, and the inhibitory effect of isorhamnetin on inflammation was significantly attenuated., Conclusion: Isorhamnetin inhibits macrophage inflammation and protects kidney in AKI may be related to downregulating Mincle/Syk/NF-κB-maintained macrophage phenotype by activating SLPI.

Introduction: The end of gestation, ensuing parturition, and the neonatal period represent highly dynamic phases for immunological changes in both mother and offspring. The regulation of innate immune cells at the maternal-fetal interface during late term pregnancy, after birth, and during microbial colonization of the neonatal gut and other mucosal surfaces, is crucial for controlling inflammation and maintaining homeostasis. Innate immune cells and mucosal epithelial cells express antileukoproteinase (SLPI), which has anti-inflammatory and anti-protease activity that can regulate cellular activation., Methods: Here, we developed and validated new monoclonal antibodies (mAbs) to characterize SLPI for the first time in horses. Peripheral blood and mucosal samples were collected from healthy adults horses and a cohort of mares and their foals directly following parturition to assess this crucial stage., Results: First, we defined the cell types producing SLPI in peripheral blood by flow cytometry, highlighting the neutrophils and a subset of the CD14+ monocytes as SLPI secreting immune cells. A fluorescent bead-based assay was developed with the new SLPI mAbs and used to establish baseline concentrations for secreted SLPI in serum and secretion samples from mucosal surfaces, including saliva, nasal secretion, colostrum, and milk. This demonstrated constitutive secretion of SLPI in a variety of equine tissues, including high colostrum concentrations. Using immunofluorescence, we identified production of SLPI in mucosal tissue. Finally, longitudinal sampling of clinically healthy mares and foals allowed monitoring of serum SLPI concentrations. In neonates and postpartum mares, SLPI peaked on the day of parturition, with mares returning to the adult normal within a week and foals maintaining significantly higher SLPI secretion until three months of age., Conclusion: This demonstrated a physiological systemic change in SLPI in both mares and their foals, particularly at the time around birth, likely contributing to the regulation of innate immune responses during this critical period., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Holmes, Babasyan and Wagner.)

Interstitial lung diseases (ILDs) are characterized by inflammation or fibrosis of the pulmonary parenchyma. Despite the involvement of immune cells and soluble mediators in pulmonary fibrosis, the influence of antimicrobial peptides (AMPs) remains underexplored. These effector molecules display a range of activities, which include immunomodulation and wound repair. Here, we investigate the role of AMPs in the development of fibrosis in ILD. We compare the concentration of different AMPs and different cytokines in 46 fibrotic (F-ILD) and 17 non-fibrotic (NF-ILD) patients by ELISA and using peripheral blood mononuclear cells from in vitro stimulation in the presence of lysozyme or secretory leukocyte protease inhibitor (SLPI) from 10 healthy donors. We observed that bronchoalveolar lavage (BAL) levels of AMPs were decreased in F-ILD patients (lysozyme: p < 0.001; SLPI: p < 0.001; LL-37: p < 0.001; lactoferrin: p = 0.47) and were negatively correlated with levels of TGF-β (lysozyme: p = 0.02; SLPI: p < 0.001) and IL-17 (lysozyme: p < 0.001; SLPI: p < 0.001). We observed that lysozyme increased the percentage of CD86 + macrophages ( p < 0.001) and the production of TNF-α ( p < 0.001). We showed that lysozyme and SLPI were associated with clinical parameters (lysozyme: p < 0.001; SLPI: p < 0.001) and disease progression (lysozyme: p < 0.001; SLPI: p = 0.01). These results suggest that AMPs may play an important role in the anti-fibrotic response, regulating the effect of pro-fibrotic cytokines. In addition, levels of lysozyme in BAL may be a potential biomarker to predict the progression in F-ILD patients., Competing Interests: The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Osseointegration is vital to success in orthopedic and dental reconstructions with implanted materials. The bone matrix or cells-particularly osteoblasts-are required to achieve functional contact on the implant surface. Osteoblast induction is therefore essential for osteogenesis to occur. Enhancement of osteoblast adhesion, proliferation, and differentiation, particularly by implant surface modifications, have been found challenging to develop. Secretory Leukocyte Protease Inhibitor (SLPI), a cation ionic protein with anti-inflammatory and anti-bacterial activities, showed activation in osteoblast proliferation and differentiation. However, the effects of coating recombinant human (rh) SLPI on a titanium alloy surface on human osteoblast adhesion, proliferation, and differentiation has never been investigated. In this study, titanium alloys (Ti-6Al-4V) were coated with rhSLPI, while human osteoblast adhesion, proliferation, differentiation, actin cytoskeletal organization, and gene expressions involved in cell adhesion and differentiation were investigated. The results indicate that coating titanium with 10-100 µg/ml rhSLPI enhanced the physical properties of the Ti surface and enhanced human osteoblast (hFOB 1.19) cell adhesion, activated actin dynamic, enhanced adhesive forces, upregulated integrins α1, α2, and α5, enhanced cell proliferation, mineralization, alkaline phosphatase activity, and upregulated ALP, OCN, and Runx2. This is the first study to demonstrate that coating SLPI on titanium surfaces enhances osseointegration and could be a candidate molecule for surface modification in medical implants., (© 2024. The Author(s).)

Aging is a complex process involving various systems and behavioral changes. Altered immune regulation, dysbiosis, oxidative stress, and sleep decline are common features of aging, but their interconnection is poorly understood. Using Drosophila, we discover that IM33, a novel immune modulator, and its mammalian homolog, secretory leukocyte protease inhibitor (SLPI), are upregulated in old flies and old mice, respectively. Knockdown of IM33 in glia elevates the gut reactive oxygen species (ROS) level and alters gut microbiota composition, including increased Lactiplantibacillus plantarum abundance, leading to a shortened lifespan. Additionally, dysbiosis induces sleep fragmentation through the activation of insulin-producing cells in the brain, which is mediated by the binding of Lactiplantibacillus plantarum-produced DAP-type peptidoglycan to the peptidoglycan recognition protein LE (PGRP-LE) receptor. Therefore, IM33 plays a role in the glia-microbiota-neuronal axis, connecting neuroinflammation, dysbiosis, and sleep decline during aging. Identifying molecular mediators of these processes could lead to the development of innovative strategies for extending lifespan., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Psoriasis, which involves mast cells, is a chronic inflammatory skin disorder whose pathophysiology is still not fully understood. We investigated the role of secretory leukocyte protease inhibitor (SLPI), a potential inhibitor of mastocyte serine proteases, on mast cell-dependent processes of relevance to the skin barrier defense in psoriasis. Here, we demonstrate that the dermal mast cells of patients with psoriasis express SLPI but not those of healthy donors. Moreover, SLPI transcripts were found to be markedly upregulated in murine mast cells by mediators derived from psoriasis skin explant cultures. Using mast cells from SLPI-deficient mice and their SLPI + wild-type controls, we show that SLPI inhibits the activity of serine protease chymase in mastocytes. SLPI was also found to enhance the degranulation of mast cells activated via anti-IgE Abs but not Mrgprb2 ligands. Finally, we demonstrate that the expression and function of Mrgprb2 in mast cells are suppressed by a normal and, to a larger extent, psoriatic skin environment. Together, these findings reveal mechanisms underlying FcεRI- and Mrgprb2-dependent mast cell function that have not been described previously., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Cancer is a multifaceted disorder frequently linked to the dysregulation of several biological processes. The SLPI is a multifunctional protein involved in the modulation of immunological response and the inhibition of protease activities. SLPI acts as an inhibitor of proteases, exerts antibacterial properties, and suppresses the transcription of proinflammatory genes through the nuclear factor-kappa B (NF-κB) pathway. The role of this protein as a regulatory agent has been implicated in various types of cancer. Recent research has revealed that SLPI upregulation in cancer cells enhances the metastatic capacity of epithelial malignancies, indicating the deleterious effects of this protein. Furthermore, SLPI interacts intricately with other cancer-promoting factors, including matrix metalloproteinase-2 (MMP-2), MMP-9, the NF-κB and Akt pathways, and the p53-upregulated modulator of apoptosis (PUMA). This review provides an overview of the role of SLPI in cancer pathophysiology, emphasizing its expression in cancer cells and tissues, its potential as a prognostic biomarker, and its therapeutic promise as a target in cancer treatment. The mechanisms of SLPI action in cancer, including its anti-inflammatory effects, regulation of cell proliferation and angiogenesis, and modulation of the tumor microenvironment, have been investigated. The clinical implications of SLPI in cancer have been discussed, including its potential as a diagnostic and prognostic biomarker, its role in chemoresistance, and its therapeutic potential in several types of cancer, such as hepatocellular carcinoma (HCC), colorectal cancer (CRC), pancreatic cancer, head and neck squamous cell carcinoma (HNSCC), ovarian cancer (OvCa), prostate cancer (PC), gastric cancer (GC), breast cancer, and other cancers. In addition, we emphasized the significance of SLPI in cancer, which offers fresh perspectives on potential targets for cancer therapy., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

As onset of sepsis adversely affects the prognosis of canine pyometra, finding biomarkers that would distinguish sepsis status would be useful in the clinical management. Accordingly, we hypothesized that differential expression of endometrial transcripts and circulating concentration of certain inflammatory mediators would discriminate pyometra-led sepsis (P-sepsis+) from those of pyometra without sepsis (P-sepsis-). Bitches with pyometra (n = 52) were classified into P-sepsis+ (n = 28) and P-sepsis- (n = 24) based on vital clinical score and total leukocyte count. A group of non-pyometra bitches (n = 12) served as control. The relative fold changes in the transcripts of IL6, IL8, TNFα, IL10, PTGS2, mPGES1 and PGFS, SLPI, S100A8, S100A12 and eNOS were determined by quantitative polymerase chain reaction. Furthermore, the serum concentrations of IL6, IL8, IL10, SLPI and prostaglandin F 2α metabolite (PGFM) were assayed by ELISA. The relative fold changes in S100A12 and SLPI and mean concentrations of IL6 and SLPI were significantly (p < .05) higher in P-sepsis+ than that of P-sepsis- group. Receiver operating characteristic analysis revealed that serum IL6 had a diagnostic sensitivity of 78.6% and a positive likelihood ratio (LR+) of 2.09, at a cut-off value of 15.7 pg/mL to diagnose P-sepsis+ cases. Similarly, serum SLPI had a sensitivity of 84.6% and an LR+ of 2.23, at a cut-off value of 2.0 pg/mL. It was concluded that SLPI and IL6 would serve as putative biomarkers for pyometra-led sepsis in bitches. Monitoring SLPI and IL6 would be a useful adjunct to the established haemato-biochemical parameters in customizing the treatment strategies and arriving at the decision for management of pyometra bitches with critical illness., (© 2023 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.)

Cystic endometrial hyperplasia (CEH)-pyometra (CEH-P) is one of the most common reproductive disorders in bitches, posing a risk to both future fertility and life. The aims of the current study were to elucidate the differential expression patterns of inflammatory mediators at transcript and protein levels in the endometrium and to assess the concentrations of key inflammatory mediators in the peripheral circulation of bitches with different graded CEH-P. A total of 25 client-owned intact mixed breed bitches of 3-10 years presented to the outpatient department of RVP-TVCC of the institute were considered for the study. Of which, 22 cases suggestive of pyometra and 3 cases of CEH obtained during routine elective ovariohysterectomy were subjected to histopathological examination. Uteri were categorized into CEH (n = 3), moderate CEH-P (mCEH-P, n = 9), severe CEH-P (sCEH-P, n = 6) and atrophic pyometra (AT-P, n = 7). A group of age matched (n = 12) bitches without pyometra served as control. Endometrial transcripts such as IL6, IL8, PTGS2, PGFS, and SLPI were expressed differentially in the CEH and CEH-P bitch. In addition, a strong immunoreactivity (IR) of IL6, IL8, PTGS2, and mPGES1 was recorded in the sCEH-P uterus, while expression of IL10 was noticed in AT-P. In circulation, serum IL6 was the most relevant marker with high sensitivity of 96.2% and specificity of 84.6% at a cut off concentration 8.5 pg/mL followed by SLPI with 95.2% sensitivity, and 84.6% specificity at cut off concentration of 1.3 ng/mL. Serum IL10, PGFM and SLPI concentration in the peripheral circulation were 1.5-2.23 fold higher in mCEH-P, 0.87-2.5 fold higher in sCEH-P and 2.9-3.5 fold higher in AT-P than that of control. It is concluded that monitoring the serum concentration of IL6, IL10 and SLPI would be useful adjunct to the established hematobiochemical parameters in the management of pyometra in the bitch with critical illness., Competing Interests: Declaration of competing interest Authors do not have any conflict of interests to declare., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Secretory leucoprotease inhibitor (SLPI) has multifaceted functions, including inhibition of protease activity, antimicrobial functions, and anti-inflammatory properties. In this study, we show that SLPI plays a role in controlling pulmonary Pseudomonas aeruginosa infection. Mice lacking SLPI were highly susceptible to P. aeruginosa infection, however there was no difference in bacterial burden. Utilising a model of P. aeruginosa LPS-induced lung inflammation, human recombinant SLPI (hrSLPI) administered intraperitoneally suppressed the recruitment of inflammatory cells in the bronchoalveolar lavage fluid (BALF) and resulted in reduced BALF and serum levels of inflammatory cytokines and chemokines. This anti-inflammatory effect of hrSLPI was similarly demonstrated in a systemic inflammation model induced by intraperitoneal injection of LPS from various bacteria or lipoteichoic acid, highlighting the broad anti-inflammatory properties of hrSLPI. Moreover, in bone-marrow-derived macrophages, hrSLPI reduced LPS-induced phosphorylation of p-IkB-α, p-IKK-α/β, p-P38, demonstrating that the anti-inflammatory effect of hrSLPI was due to the inhibition of the NFκB and MAPK pathways. In conclusion, administration of hrSLPI attenuates excessive inflammatory responses and is therefore, a promising strategy to target inflammatory diseases such as acute respiratory distress syndrome or sepsis and could potentially be used to augment antibiotic treatment.

Ovarian cancer is the most lethal gynecological malignancy worldwide with high metastasis and poor prognosis rates. Cancer-associated fibroblasts (CAFs), a heterogeneous population of cells that constitutes a major component of the tumor microenvironment, secrete extracellular vesicles (EVs) loading with proteins, lipids, and RNAs to promote tumorigenesis. However, the specific roles of CAF-derived proteins contained in EVs in ovarian cancer remain poorly understood at present. Using the gene expression microarray analysis, we identified a list of dysregulated genes between the α-SMA + CAF and FAP + CAF subpopulations, from which secretory leukocyte protease inhibitor (SLPI) was chosen for further validation. Quantitative PCR, western blot, immunohistochemistry, and enzyme-linked immunosorbent assays were used to assess SLPI expression in ovarian cancer cells, tissues, CAFs, and EVs. Additionally, we evaluated the effects of exogenous SLPI on proliferation, migration, invasion, and adhesion of ovarian cancer cells in vitro. Our results showed SLPI protein was upregulated in CAFs, particularly in the FAP high α-SMA low CAF subpopulation, and associated with increased tumor grade and decreased overall survival (OS). Importantly, CAF-derived SLPI protein could be encapsulated in EVs for delivery to ovarian cancer cells, thus facilitating cell proliferation, migration, invasion, and adhesion via activating the PI3K/AKT and downstream signaling pathways. Moreover, high plasma expression of SLPI encapsulated in EVs was closely correlated with tumor stage in ovarian cancer patients. Our collective results highlight an oncogenic role of plasma EV-encapsulated SLPI secreted by CAFs in tumor progression for the first time, supporting its potential utility as a prognostic biomarker of ovarian cancer., (© 2022 The Authors. Molecular Carcinogenesis published by Wiley Periodicals LLC.)

Background: Secretory leukocyte protease inhibitor (SLPI), a ~12 kDa protein is an important regulator of innate and adaptive immunity and a component of tissue regenerative programmes. SLPI expression is markedly elevated in chronically inflamed skin, including that of individuals suffering from psoriasis. However, the role of SLPI in these diseases remains elusive., Objectives: The poor understanding of the early stages of the development of psoriasis is a major obstacle to successful intervention in the skin pathology. We hypothesized that SLPI and peripheral nerves that might be activated early in the progression of the disease likely form a functional relationship to maintain skin barrier homeostasis and respond to a variety of threats., Methods: We used skin biopsies of healthy donors and individuals with psoriasis to show expression pattern of SLPI. A role of SLPI in psoriasis was mechanistically assessed using SLPI-deficient mice and an imiquimod (IMQ)-induced experimental model of psoriasis., Results: We show that mice lacking SLPI had exaggerated skin alterations that extended beyond the treatment site in an imiquimod-induced psoriasis. The spatiotemporally distinct skin responses in SLPI-deficient mice, compared to their wild-type littermates, resulted from a compromised skin barrier function that manifested itself in heightened transepidermal water loss through the larger skin area surrounding the IMQ-challenged skin. The increased pathogenic skin changes in the absence of SLPI were reversible through pharmacological treatment that blocks a nerve-reflex arc., Conclusions: Together, these data indicate that SLPI plays a protective role in psoriasis through preventing skin dryness, inherent in the pathogenesis of psoriasis and that this SLPI action depends on neuronal input operating in a reflex manner. These findings reveal a previously unrecognized mechanism that maintains cutaneous homeostasis, which involves a crosstalk between the nervous system and a protein anatomically poised to fortify the epidermal permeability barrier., (© 2022 The Authors. Journal of the European Academy of Dermatology and Venereology published by John Wiley & Sons Ltd on behalf of European Academy of Dermatology and Venereology.)

Secretory leukocyte protease inhibitor (SLPI) is a pleiotropic protein produced by healthy intestinal epithelial cells. SLPI regulates NF-κB activation, inhibits neutrophil proteases and has broad antimicrobial activity. Recently, increased SLPI expression was found in various types of carcinomas and was suggested to increase their metastatic potential. Indeed, we demonstrated that SLPI protein expression in colorectal cancer (CRC) liver metastases and matched primary tumors is associated with worse outcome, suggesting that SLPI promotes metastasis in human CRC. However, whether SLPI plays a role in CRC before distant metastases have formed is unclear. Therefore, we examined whether SLPI expression is associated with prognosis in CRC patients with localized disease. Using a cohort of 226 stage II and 160 stage III CRC patients we demonstrate that high SLPI protein expression is associated with reduced disease recurrence in patients with stage III micro-satellite stable tumors treated with adjuvant chemotherapy, independently of established clinical risk factors (hazard rate ratio 0.54, P-value 0.03). SLPI protein expression was not associated with disease-free survival in stage II CRC patients. Our data suggest that the role of SLPI in CRC may be different depending on the stage of disease. In stage III CRC, SLPI expression may be unfavorable for tumors, whereas SLPI expression may be beneficial for tumors once distant metastases have established., (© 2022. The Author(s).)

Objective: Even with our best practices, we are frequently unable to prevent slow and stalled wound healing-particularly in people with impaired circulation and conditions such as diabetes. As a result, greater insight into the nature of wound healing and alternative treatment approaches is needed. An avenue that may be of particular promise is increasing understanding of the role of secretory leukocyte protease inhibitor (SLPI) as there is evidence that it enhances wound healing, its expression increases in response to inflammation and infection, and it exhibits anti-protease, anti-inflammatory, antiviral antibacterial and antifungal activities., Method: The response of SLPI levels to wounding and skin injury was assessed by taking punch skin biopsies from healthy volunteers and assessing the levels of SLPI at the site of injury at the time of wounding (baseline) as well as one, two, three, four, seven, nine and 12 weeks later., Results: A total of 35 volunteers took part in the study. Significant elevations were found: levels of SLPI were greatly increased, 12 times that at baseline, and remained elevated at three weeks despite re-epithelialisation having occurred., Conclusion: These findings not only suggest that levels of SLPI rise rapidly following wounding, but that these elevations are sustained, and continue to increase even when re-epithelialisation has occurred. These results suggest that the role and potential benefits of this protease inhibitor deserve further exploration.

Secretory leukocyte protease inhibitor (SLPI) is a small but powerful member of the serine protease inhibitor family, which includes proteins such as elafin and α1-antitrypsin. These proteins all have similar structures and antiprotease abilities, but SLPI has been found to have an additional role as an anti-inflammatory factor. It can inhibit the production of pro-inflammatory cytokines in cells stimulated with lipopolysaccharide, prevent neutrophil infiltration in murine models of lung and liver injury, and regulate the activity of the transcription factor NF-κB. In this review, we will revisit SLPI's unique biochemistry, and then explore how its anti-inflammatory functions can be linked to more recent findings showing that SLPI can localize to the nuclei of cells, bind DNA, and act as a regulator of gene expression.

Due to the global challenge of donor kidney shortage, expanding the pool of deceased donors has been proposed to include expanded criteria donors. However, the lack of methods to precisely measure donor kidney injury and predict the outcome still leads to high discard rates and recipient complications. As such, evaluation of deceased donor kidney quality is critical prior to transplantation. Biomarkers from donor urine or serum provide potential advantages for the precise measure of kidney quality. Herein, simultaneous detection of secretory leukocyte peptidase inhibitor (SLPI) and interleukin 18 (IL-18), two important kidney injury biomarkers, has been achieved, for the first time, with an ultra-high sensitivity using surface enhanced Raman scattering (SERS). Specifically, black phosphorus/gold (BP/Au) nanohybrids synthesized by depositing Au nanoparticles (NPs) onto the BP nanosheets serve as SERS-active substrates, which offer a high-density of inherent and accessible hot-spots. Meanwhile, the nanohybrids possess biocompatible surfaces for the enrichment of target biomarkers through the affinity with BP nanosheets. Quantitative detection of SLPI and IL-18 were then achieved by characterizing SERS signals of these two biomarkers. The results indicate high sensitivity and excellent reproducibility of this method. The limits of detection reach down to 1.53×10 -8 mg/mL for SLPI and 0.23×10 -8 mg/mL for IL-18. The limits of quantification are 5.10×10 -8 mg/mL and 7.67×10 -9 mg/mL for SLPI and IL-18. In addition, simultaneous detection of these biomarkers in serum was investigated, which proves the feasibility in biologic environment. More importantly, this method is powerful for detecting multiple analytes inheriting from excellent multiplexing ability of SERS. Giving that the combined assessment of SLPI and IL-18 expression level serves as an indicator of donor kidney quality and can be rapidly and reproducibly conducted, this SERS-based method holds great prospective in clinical practice.

The impact of steroid hormones estrogen and progesterone on human immunodeficiency virus type 1 (HIV-1) replication is well documented. However, the exact mechanism involved in the regulation of HIV-1 replication by estrogen and progesterone is still unclear. In the present study, we wanted to elucidate the molecular mechanisms underlying the modulation of HIV-1 replication by estrogen and progesterone. To achieve this goal, we used real-time quantitative PCR arrays (PCR arrays) to identify differentially expressed host genes in response to hormone treatments that are involved in antiviral responses. Our in vitro results suggest that treatment with high doses of estrogen and progesterone promotes the expression of host antiviral factors Secretory leukocyte protease inhibitor (SLPI) and Serpin family C member 1 (SERPIN C1) among others produced in response to HIV-1 infection. SLPI is an enzyme that inhibits human leukocyte elastase, human cathepsin G, human trypsin, neutrophil elastase, and mast cell chymase. SERPIN C1 is a plasma protease inhibitor that regulates the blood coagulation cascade by the inhibition of thrombin and other activated serine proteases of the coagulation system. A dose dependent downmodulation of HIV-1 replication was observed in monocyte-derived macrophages (MDMs) pre-treated with the two proteins SLPI and SERPIN C1. Further investigations suggests that the host antiviral factors, SLPI and SERPIN C1 act at the pre-integration stage, inhibiting HIV-1 viral entry and leading to the observed downmodulation of HIV-1 replication. Our studies would help identify molecular mechanisms and pathways involved in HIV-1 pathogenesis.

Background: The lower airways microbiome and host immune response in chronic pulmonary diseases are incompletely understood. We aimed to investigate possible microbiome characteristics and key antimicrobial peptides and proteins in idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD)., Methods: 12 IPF patients, 12 COPD patients and 12 healthy controls were sampled with oral wash (OW), protected bronchoalveolar lavage (PBAL) and right lung protected sterile brushings (rPSB). The antimicrobial peptides and proteins (AMPs), secretory leucocyte protease inhibitor (SLPI) and human beta defensins 1 and 2 (hBD-1 & hBD-2), were measured in PBAL by enzyme linked immunosorbent assay (ELISA). The V3V4 region of the bacterial 16S rDNA gene was sequenced. Bioinformatic analyses were performed with QIIME 2., Results: hBD-1 levels in PBAL for IPF were lower compared with COPD. The predominant phyla in IPF were Firmicutes, Bacteroides and Actinobacteria; Proteobacteria were among top three in COPD. Differential abundance analysis at genus level showed significant differences between study groups for less abundant, mostly oropharyngeal, microbes. Alpha diversity was lower in IPF in PBAL compared to COPD (p = 0.03) and controls (p = 0.01), as well as in rPSB compared to COPD (p = 0.02) and controls (p = 0.04). Phylogenetic beta diversity showed significantly more similarity for IPF compared with COPD and controls. There were no significant correlations between alpha diversity and AMPs., Conclusions: IPF differed in microbial diversity from COPD and controls, accompanied by differences in antimicrobial peptides. Beta diversity similarity between OW and PBAL in IPF may indicate that microaspiration contributes to changes in its microbiome., Competing Interests: Data collection in the study was partially funded by a grant from the regional health authorities ("Helse-Vest") in 2014, to the last author, Tomas Eagan. Helse-Vest do not use grant numbers for their annual grant distribution. The funder web site is: "https://helse-vest.no/en/research-and-co-operation". Dr. Knudsen received grants from the Norwegian Thoracic Society and Boehringer Ingelheim during the study. This does not alter our adherence to PLOS ONE policies on sharing data and materials. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

All cancers emerge after a period of clonal selection and subsequent clonal expansion. Although the evolutionary principles imparted by genetic intratumour heterogeneity are becoming increasingly clear 1 , little is known about the non-genetic mechanisms that contribute to intratumour heterogeneity and malignant clonal fitness 2 . Here, using single-cell profiling and lineage tracing (SPLINTR)-an expressed barcoding strategy-we trace isogenic clones in three clinically relevant mouse models of acute myeloid leukaemia. We find that malignant clonal dominance is a cell-intrinsic and heritable property that is facilitated by the repression of antigen presentation and increased expression of the secretory leukocyte peptidase inhibitor gene (Slpi), which we genetically validate as a regulator of acute myeloid leukaemia. Increased transcriptional heterogeneity is a feature that enables clonal fitness in diverse tissues and immune microenvironments and in the context of clonal competition between genetically distinct clones. Similar to haematopoietic stem cells 3 , leukaemia stem cells (LSCs) display heritable clone-intrinsic properties of high, and low clonal output that contribute to the overall tumour mass. We demonstrate that LSC clonal output dictates sensitivity to chemotherapy and, although high- and low-output clones adapt differently to therapeutic pressure, they coordinately emerge from minimal residual disease with increased expression of the LSC program. Together, these data provide fundamental insights into the non-genetic transcriptional processes that underpin malignant clonal fitness and may inform future therapeutic strategies., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Secretory leukocyte protease inhibitor (SLPI) has been reported to function as a regulatory factor in several cancers. However, its biological functions and underlying mechanisms in HCC remain to be uncovered. Here, we aimed to explore the effect of SLPI in HCC. In our study, we found that the mRNA and protein expression levels of SLPI were significantly down-regulated in HCC tissues and hepatoma cell lines and low level of SLPI predicted worse survival in our HCC cohorts. In term of function, silencing of SLPI markedly promoted whereas overexpression SLPI suppressed proliferation, migration and invasion capabilities of HCC cells in vitro , and ectopic expression of SLPI inhibited the tumorigenicity of HCC cells in vivo . Mechanistic studies demonstrated that SLPI played a protective role in HCC progression via activating endoplasmic reticulum stress (ER stress)-mediated apoptosis of hepatoma cells, which could be regulated by MAPK signaling pathways. In summary, our findings highlight that SLPI could serve as a potential prognostic biomarker and putative tumor suppressor by enhancing ER stress-induced apoptosis in HCC cells mediated by MAPK signaling pathways, which provides new insights into promising therapeutic targets for HCC treatment., Competing Interests: Competing Interests: We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work; there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (© The author(s).)

Background: Patients with ELANE variants and severe congenital neutropenia (SCN) commonly develop oral complications. Whether they are caused only by low neutrophil count or the combination of neutropenia and aberrant dental cells is unknown., Methods: Genetic variant was identified with exome sequencing. Dental pulp cells isolated from the SCN patient with an ELANE mutation were investigated for gene expression, enzyme activity, proliferation, colony formation, wound healing, apoptosis, ROS, attachment, spreading and response to lipopolysaccharide., Results: ELANE cells had diminished expression of ELANE and SLPI and reduced neutrophil elastase activity. Moreover, ELANE cells exhibited impaired proliferation, colony forming, migration, attachment and spreading; and significantly increased ROS formation and apoptosis, corresponding with increased Cyclin D1 and MMP2 levels. The intrinsic levels of TGF-β1 and TNF-α were significantly increased; however, IL-6, IL-8 and NF-kB1 were significantly decreased in ELANE cells compared with those in controls. After exposure to lipopolysaccharide, ELANE cells grew larger, progressed to more advanced cell spreading stages and showed significantly increased SLPI, TNF-α and NF-kB1 and tremendously increased IL-6 and IL-8 expression, compared with controls., Conclusion: This study, for the first time, suggests that in addition to neutropenia, the aberrant levels and functions of ELANE, SLPI and their downstream molecules in pulp cells play an important role in oral complications in SCN patients. In addition, pulp cells with diminished neutrophil elastase and SLPI are highly responsive to inflammation., (© 2021 The Authors. Cell Proliferation published by John Wiley & Sons Ltd.)

Background: Rates of oropharyngeal cancer (OPC) associated with alcohol & tobacco use have decreased, while human papillomavirus (HPV) associated OPC has increased among men in the US. Secretory leukocyte protease inhibitor (SLPI), detectable in a variety of secretions, has been implicated in cancers of the head and neck, associated with tumor progression and anti-viral activity. Using the recently verified oral gargle specimen, this study aimed to assess the association of salivary SLPI expression with risk of OPC and response to treatment., Methods: A case-control study design compared levels of salivary SLPI among OPC cases to age and tobacco smoking matched healthy controls. Oral HPV DNA and SLPI was quantified from oral gargle specimens. Logistic regression estimated odds ratios (OR) and 95% confidence intervals (CI) for associations of oral SLPI and risk of OPC and treatment outcomes., Results: In crude and adjusted analyses of 96 OPC cases and 97 age- and smoking-matched controls, OPC was not significantly associated with oral gargle SLPI levels. Among cases, oral SLPI was associated with tonsillectomy (p = 0.018) and among controls oral SLPI was associated with HPV in the oral gargle (p = 0.008). Higher concentrations of SLPI was significantly associated with increased odds of incomplete treatment response (T2: OR: 12.39; 95% CI: 1.44-106.72; T3: OR: 9.86; 95% CI: 1.13-85.90) among all cases, but not among P16+ cases., Conclusions: Salivary SLPI was not associated with OPC risk but was associated with higher odds of an incomplete treatment response., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: ARG is a member of several scientific advisory boards of Merck & Co, Inc, and her institution has received funding to conduct investigator-initiated studies as well as Merck sponsored vaccine clinical trials. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Secretory leukocyte peptidase inhibitor (SLPI) is a biomarker present in the respiratory tract that protects against tissue destruction and aids in wound healing. We examined whether SLPI in pleural effusion can be used to distinguish benign asbestos pleural effusion (BAPE) from early-stage malignant pleural mesothelioma (MPM) and other diseases. We measured the levels of SLPI, hyaluronic acid (HA), soluble mesothelin-related peptides (SMRP), CCL2, galectin-3, and CYFRA21-1 in 51 patients with BAPE, 37 patients with early-stage MPM, 77 patients with pleural effusions due to non-small-cell lung cancer (LCa), and 74 patients with other pleural effusions. SLPI levels in the pleural fluid of patients with BAPE were significantly lower than those in patients with MPM, LCa, and other pleural effusions (p < 0.0001). The area under the curve (AUC) for SLPI's ability to distinguish BAPE from MPM was 0.902, with a sensitivity of 82.4% and a specificity of 86.5%. This AUC was not only favourable but was better than the AUC for the ability of CYFRA21-1 to distinguish BAPE (0.853). The combination of SLPI and CYFRA21-1 achieved an AUC of 0.965 for the differentiation between BAPE and MPM. Pleural fluid SLPI as well as CYFRA21-1 and HA is useful as a biomarker to diagnose BAPE, which needs to be distinguished from early-stage MPM.

Cancer cell genetic variability and similarity to host cells have stymied development of broad anti-cancer therapeutics. Our innate immune system evolved to clear genetically diverse pathogens and limit host toxicity; however, whether/how innate immunity can produce similar effects in cancer is unknown. Here, we show that human, but not murine, neutrophils release catalytically active neutrophil elastase (ELANE) to kill many cancer cell types while sparing non-cancer cells. ELANE proteolytically liberates the CD95 death domain, which interacts with histone H1 isoforms to selectively eradicate cancer cells. ELANE attenuates primary tumor growth and produces a CD8 + T cell-mediated abscopal effect to attack distant metastases. Porcine pancreatic elastase (ELANE homolog) resists tumor-derived protease inhibitors and exhibits markedly improved therapeutic efficacy. Altogether, our studies suggest that ELANE kills genetically diverse cancer cells with minimal toxicity to non-cancer cells, raising the possibility of developing it as a broad anti-cancer therapy., Competing Interests: Declaration of interests L.B. and C.C. are inventors on the following patent applications: UC provisional applications 62/610,711 and 62/520,325, PCT/US18/37800 and associated national filings; and US provisional application 62/782,690 and PCT/US19/67890; each filed by the University of Chicago. L.B. is an inventor on provisional patent application 63/067,059, filed by Onchilles Pharma. L.B. is a co-founder of Onchilles Pharma, a company seeking to develop ELANE/PPE-based cancer therapeutics., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Osteoclastic bone resorption and osteoblastic bone formation/replenishment are closely coupled in bone metabolism. Anabolic parathyroid hormone (PTH), which is commonly used for treating osteoporosis, shifts the balance from osteoclastic to osteoblastic, although it is unclear how these cells are coordinately regulated by PTH. Here, we identify a serine protease inhibitor, secretory leukocyte protease inhibitor (SLPI), as a critical mediator that is involved in the PTH-mediated shift to the osteoblastic phase. Slpi is highly upregulated in osteoblasts by PTH, while genetic ablation of Slpi severely impairs PTH-induced bone formation. Slpi induction in osteoblasts enhances its differentiation, and increases osteoblast-osteoclast contact, thereby suppressing osteoclastic function. Intravital bone imaging reveals that the PTH-mediated association between osteoblasts and osteoclasts is disrupted in the absence of SLPI. Collectively, these results demonstrate that SLPI regulates the communication between osteoblasts and osteoclasts to promote PTH-induced bone anabolism.

Objective: Osteoarthritic cartilage destruction can be regulated by the balance between proteases and anti-proteases. Here, we sought to identify novel cellular protease inhibitors associated with osteoarthritis (OA) pathogenesis., Methods: Candidate molecules were screened from microarray data of chondrocytes treated with OA-associated catabolic factors. The functions of candidate molecules in OA pathogenesis were examined in primary-culture mouse articular chondrocytes and mouse models of OA, such as those stimulated by destabilization of the medial meniscus (DMM) or intra-articular (IA) injection of adenovirus expressing the candidate gene. The value of the selected candidate molecule as a biomarker of OA was examined by measuring its circulating levels in human and mouse blood., Results: Bioinformatic analysis identified secretory leukocyte peptidase inhibitor (SLPI) as a highly upregulated cellular protease inhibitor in chondrocytes treated with pathogenic catabolic factors, including interleukin (IL)-1β, hypoxia-inducible factor (HIF)-2α, and zinc importer ZIP8. The adenovirus-mediated overexpression of SLPI in joint tissues did not cause any OA-like change or modulate DMM- or HIF-2α-induced experimental OA in mice. SLPI also did not markedly modulate the expression of OA-associated catabolic or anabolic factors in chondrocytes. However, SLPI was specifically upregulated in OA cartilage, and the serum SLPI levels were significantly elevated in human OA patients and experimental OA mice, suggesting that SLPI may be a biomarker of OA., Conclusion: Although SLPI is upregulated in OA chondrocytes, it does not appear to per se modulate OA development in mice. However, it may be a potential biomarker of OA in humans and animal models., (Copyright © 2021 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Secretory leukocyte protease inhibitor (SLPI) and progranulin (PGRN) are secretory proteins with an anti-inflammatory property. Their involvement in cervical remodeling in pregnant uterus is not yet elucidated. Thus, this study aimed to explore the significance of SLPI and PGRN in the maintenance of pregnancy by investigating the factors associated with their expression levels at the cervix. Concentrations of SLPI and PGRN proteins were measured in cervical mucus samples collected from asymptomatic pregnant women at 24-26 weeks of gestation (n = 166). The concentrations of those molecules were analyzed with clinical parameters related to risk for preterm delivery (PD). In pregnant mice, we evaluated the effect of lipopolysaccharide-induced inflammation and progesterone effect modulation on cervical mRNA expression of SLPI and PGRN. The cervical PGRN level was significantly lower in women with short cervix (<35 mm) and with a history of threatened PD. In women with short cervix, cervical SLPI concentrations were positively correlated with inflammatory cytokines, interleukin-6 (R 2 = 0.75) and interleukin-8 (R 2 = 0.71). In pregnant mice, cervical mRNA expressions of PGRN and SLPI were increased in response to progesterone supplementation and were suppressed by a progesterone antagonist, mifepristone. Lipopolysaccharide-induced inflammation caused remarkable upregulation in cervical SLPI mRNA level but not in PGRN. Progesterone and local inflammation are the factors controlling expression levels of PGRN and SLPI at the cervix. The observed relationship of PGRN and SLPI levels in the cervical mucus with PD-related clinical parameters supports that those anti-inflammatory molecules possibly play a significant role in appropriate regulation of cervical remodeling., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: Antimicrobial peptides and proteins (AMPs) constitute the first line of defense against pathogenic microorganisms in the airway. The association between AMPs and chronic rhinosinusitis with nasal polyps (CRSwNP) requires further investigations. This study is aimed at investigating the expression and regulation of major dysregulated AMPs in the nasal mucosa of CRSwNP., Methods: The expression of AMPs was analyzed in nasal tissue from patients with eosinophilic (E) CRSwNP and nonECRSwNP and healthy subjects using RNA sequencing. The 10 most abundant AMPs expressed differentially in CRSwNP patients were verified by real-time PCR, and of these, the expression and regulation of secretory leukoprotease inhibitor (SLPI) and clusterin (CLU) were investigated further., Results: The 10 most abundant AMPs expressed differentially in CRSwNP compared to healthy control, regardless of subtypes, included BPIFA1, BPIFB1, BPIFB2, CLU, LTF, LYZ, and SLPI, which were downregulated, and S100A8, S100A9, and HIST1H2BC, which were upregulated. ELISA and immunofluorescence confirmed the decreased expression of SLPI and CLU levels in CRSwNP. SLPI is expressed in both nasal epithelial cells and glandular cells, whereas CLU is mainly expressed in glandular cells. AB/PAS staining further demonstrated that both SLPI and CLU were mainly produced by mucous cells in submucosal glands. Furthermore, the numbers of submucosal glands were significantly decreased in nasal polyp tissue of CRSwNP compared to nasal tissue of controls. SLPI was downregulated by TGF- β 1 and IL-4 in cultured nasal tissues in vitro , while CLU expression was inhibited by TGF- β 1. Glucocorticoid treatment for 2 weeks significantly increased the expression of all downregulated AMPs, but not LYZ. Additionally, budesonide significantly increased the expression of SLPI and CLU in cultured nasal tissues., Conclusion: The expression of major antimicrobial proteins is significantly decreased in nasal tissue of CRSwNP. The expression of SLPI and CLU is correlated with the numbers of submucosal glands and regulated by inflammatory cytokines and glucocorticoids., Competing Interests: The authors declare they have no competing interests., (Copyright © 2021 Yanran Huang et al.)

To elucidate the underlying mechanism of secretory leukocyte protease inhibitor (SLPI)-induced cell migration, we compared SLPI-deleted human gingival carcinoma Ca9-22 (ΔSLPI) cells and original (wild-type: wt) Ca9-22 cells using several microscopic imaging methods and gene expression analysis. Our results indicated reduced migration of ΔSLPI cells compared to wtCa9-22 cells. The lamellipodia/dorsal ruffles were smaller and moved slower in ΔSLPI cells compared to wtCa9-22 cells. Furthermore, well-developed intermediate filament bundles were observed at the desmosome junction of ΔSLPI cells. In addition, Galectin4 was strongly expressed in ΔSLPI cells, and its forced expression suppressed migration of wtCa9-22 cells. Taken together, SLPI facilitates cell migration by regulating lamellipodia/ruffles and desmosomes, in which Galectin4 plays an important role.

Homeostatic mucosal immune responses are fine-tuned by naturally evolved interactions with native microbes, and integrating these relationships into experimental models can provide new insights into human diseases. Here, we leverage a murine-adapted airway microbe, Bordetella pseudohinzii (Bph), to investigate how chronic colonization impacts mucosal immunity and the development of allergic airway inflammation (AAI). Colonization with Bph induces the differentiation of interleukin-17A (IL-17A)-secreting T-helper cells that aid in controlling bacterial abundance. Bph colonization protects from AAI and is associated with increased production of secretory leukocyte protease inhibitor (SLPI), an antimicrobial peptide with anti-inflammatory properties. These findings are additionally supported by clinical data showing that higher levels of upper respiratory SLPI correlate both with greater asthma control and the presence of Haemophilus, a bacterial genus associated with AAI. We propose that SLPI could be used as a biomarker of beneficial host-commensal relationships in the airway., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Behçet's disease (BD) is a vasculitis of unknown aetiology typified by chronic recurrent oral ulcers and systemic inflammatory manifestations. Neutrophils, and specifically their protease neutrophil elastase (NE), have been implicated in its pathology. Although NE is an effective anti-microbial, excessive NE can damage host tissue. Recurrent oral ulceration is a primary BD symptom, therefore we hypothesized that excessive neutrophil infiltration evidenced by increased NE and a reduction in specific endogenous inhibitors, secretory leucocyte protease inhibitor (SLPI) and alpha1-anti-trypsin (α1AT) contributes to BD mucosal instability. NE, SLPI and α1AT were quantified in saliva from BD patients with active oral ulcers (BDa) and quiet without ulcers (BDq), recurrent aphthous stomatitis (RASa; RASq) and healthy controls (HC). Although BDq saliva had marginally higher median NE levels (1112 ng/ml) compared to both RASq (1043 ng/ml) and HC (999 ng/ml), SLPI was significantly reduced in BDq (P < 0·01). Despite decreased SLPI protein, mRNA expression was significantly increased in BDq buccal epithelial swabs compared to RASq and HC (P < 0·05, P < 0·001). NE remained enzymatically active, although α1AT levels were at least eight times higher than SLPI in all groups, suggesting that α1AT does not have a primary role in counteracting NE in saliva. Furthermore, NE levels in BDa patients medicated with both azathioprine (AZA) and colchicine (COLC) were significantly lower than those on COLC (P = 0·0008) or neither (P = 0·02), indicating that combining AZA + COLC may help to regulate excessive NE during ulceration. This study showed that enzymatically active NE coupled with reduced SLPI in BD saliva may contribute to recurrent oral ulcerations., (© 2020 The Authors. Clinical & Experimental Immunology published by John Wiley & Sons Ltd on behalf of British Society for Immunology.)

Neutrophils are broadly classified into conventional neutrophils (PMNs) and low-density granulocytes (LDGs). LDGs are better than PMNs at generating neutrophil extracellular traps (NETs), which may contribute to the pathology of autoimmune diseases. We hypothesized that LDGs and PMNs differ in their levels of unrestrained NE that supports NET generation. Here, we show that individuals with psoriasis contain elevated levels of LDGs and that in contrast to PMNs, the LDGs display higher staining for NE and lower staining for its inhibitor SLPI. The heterogeneity between blood-derived LDGs and PMNs was somewhat reminiscent of the differences in the NE and SLPI staining patterns observed in psoriasis skin-infiltrating neutrophils. Distinctive staining for NE and SLPI in LDGs and PMNs did not result from differences in their protein levels nor manifested in higher total proteolytic activity of NE in LDGs; rather, it likely depended on different cytosolic sequestration of these proteins. The disparate profile of NE and SLPI in LDGs and PMNs coincided with altered migratory responses of these cells to cutaneous chemoattractants. Collectively, differential NE and SLPI staining identifies common attributes of both circulating and skin-infiltrating neutrophils, which may guide neutrophil migration to distinct skin regions and determine the localization of LDGs-mediated cutaneous pathology., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Netherton syndrome is a monogenic autosomal recessive disorder primarily characterized by the detachment of the uppermost layer of the epidermis, the stratum corneum It results from mutations in the SPINK5 gene, which codes for a kallikrein inhibitor. Uncontrolled kallikrein activity leads to premature desquamation, resulting in a severe epidermal barrier defect and subsequent life-threatening systemic infections and chronic cutaneous inflammation. Here, we show that genetic activation of the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nfe2l2/Nrf2) in keratinocytes of Spink5 knockout mice, a model for Netherton syndrome, significantly alleviates their cutaneous phenotype. Nrf2 activation promoted attachment of the stratum corneum and concomitant epidermal barrier function, and reduced the expression of pro-inflammatory cytokines such as tumor necrosis factor α and thymic stromal lymphopoietin. Mechanistically, we show that Nrf2 activation induces overexpression of secretory leukocyte protease inhibitor (Slpi), a known inhibitor of kallikrein 7 and elastase 2, in mouse and human keratinocytes in vivo and in vitro , respectively. In the Spink5-deficient epidermis, the upregulation of Slpi is likely to promote stabilization of corneodesmosomes, thereby preventing premature desquamation. Our results suggest pharmacological NRF2 activation as a promising treatment modality for Netherton syndrome patients.This article has an associated First Person interview with the first author of the paper., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2020. Published by The Company of Biologists Ltd.)

In this study, we used bioinformatics tools, and experiments with patient tissues and human mesenchymal stem cells (hMSCs) to identify differentially regulated genes (DEGs) and microRNAs (miRNAs) that promote postmenopausal osteoporosis. By analyzing the GSE56815 dataset from the NCBI GEO database, we identified 638 DEGs, including 371 upregulated and 267 downregulated genes, in postmenopausal women with low bone density. Enrichment and protein-protein interaction network analyses showed that TP53, RPS27A, and VEGFA were the top three hub genes with the highest degree of betweenness and closeness centrality. TargetScanHuman and DIANA software analyses and dual luciferase reporter assays confirmed that miR-16a-5p directly targets the 3'UTR of VEGFA. Postmenopausal patients with osteoporosis showed higher miR-16-5p and lower VEGFA levels than those without osteoporosis (n=10 each). VEGFA levels were higher in miR-16-5p knockdown hMSCs and were reduced in miR-16-5p-overexpressing hMSCs. mRNA expression of osteogenic markers, ALP, OCN, and RUNX2, as well as calcium deposition based on Alizarin red staining, correlated inversely with miR-16-5p levels and correlated positively with VEGFA levels. These findings suggest that miR-16-5p suppresses osteogenesis by inhibiting VEGFA expression and is a promising target for postmenopausal osteoporosis therapy.

Background: IgG4-related disease (IgG4-RD) is characterized by elevated serum IgG4 and tissue infiltration by IgG4-positive plasma cells. The pathogenesis of this disease is not clear. Transcriptome analysis was performed to identify genes over- and under-expressed in patients with IgG4-RD. Method: DNA microarray analysis was performed using RNA from peripheral blood mononuclear cells of two patients with IgG4-RD and four healthy individuals. Genes showing a greater than threefold change in expression in IgG4-RD patients following steroid therapy were identified. Four genes related to innate immunity such as transcobalamin I (TCN1), secretory leukocyte peptidase inhibitor (SLPI), bactericidal/permeability-increasing protein (BPI) and lactotransferrin (LTF) were assessed by real-time PCR in 15 IgG4-RD patients and 13 healthy individuals. Result: DNA microarray analysis identified 30 genes showing a greater than threefold change in expression in IgG4-RD patients following steroid therapy. Real-time RT-PCR showed that the levels of mRNAs encoding TCNI and SLPI, except for BPI and LTF, were significantly lower in patients with IgG4-RD than in healthy people. The levels of all four mRNAs in patients with IgG4-RD were significantly increased after steroid treatment. Conclusion: These results indicate that reduction in expression of innate immunity-related genes may participate in the pathogenesis of IgG4-RD that steroid treatment may rectify impaired innate immunity as well as acquired immunity.

Early studies suggest that the androgen receptor (AR) may play differential roles in influencing prostate cancer (PCa) and bladder cancer (BCa) metastasis, but the underlying mechanisms remain unclear. Here, we found that the AR might function via differentially altering vasculogenic mimicry (VM) formation to either decrease PCa metastasis or increase BCa metastasis. Mechanism dissection showed that the AR could differentially alter the expression of the VM marker SLPI through miR-525-5p to regulate SLPI; moreover, it could either increase miR-525-5p transcription in PCa or decrease it in BCa via binding to different androgen-response-elements (AREs) located at different positions in the miR-525 precursor promoter. Further, results from liquid chromatography-mass spectrometry (LC-MS) showed that the co-factors of AR in PCa and BCa are NFIX and HDAC2, respectively. Together, these results provide the first detailed mechanism of how the AR can differentially alter PCa and BCa metastasis; thus, targeting the newly identified AR-miR-525-5p-SLPI axis may help suppress metastasis., Competing Interests: Declaration of competing interest No potential conflicts of interest were disclosed., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Salmonella enteric serovar Typhimurium (S. Typhimurium) is a zoonotic pathogen causing public health hazards. Identification of genes related to macrophages resistance to S. Typhimurium and their immune mechanisms can provide a theoretical basis for disease resistance. In this study, sixty significant differentially expressed genes were screened between susceptible and resistant sheep macrophages by transcriptome RNA-seq. Eight significantly enriched GO terms and six canonical pathways were involved by GO and KEGG enrichment analysis. Furthermore, knockdown of HMOX1 and SLPI increased remarkably the clearance of S. typhimurium, but SPP1 had little effect on the clearance of S. Typhimurium within sheep macrophages. Altogether, these results suggest that many genes of macrophages were reprogrammed via S. Typhimurium infection, some of which may facilitate host defence against Salmonella, while others allow Salmonella to escape., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Sexually transmitted infections (STIs) and vaginal dysbiosis (disturbed resident microbiota presenting with abnormal Nugent score or candidiasis) have been associated with mucosal inflammation and risk of HIV-1 infection, cancer and poor reproductive outcomes. To date, the temporal relationships between aberrant cervical innate immunity and the clinical onset of microbial disturbance have not been studied in a large population of reproductive age women. We examined data from a longitudinal cohort of 934 Ugandan and Zimbabwean women contributing 3,274 HIV-negative visits who had complete laboratory, clinical and demographic data. Among those, 207 women later acquired HIV, and 584 women were intermittently diagnosed with C. trachomatis (CT), N. gonorrhoeae (NG), genital herpes (HSV-2), T. vaginalis (TV), candidiasis, and abnormal intermediate (4-6) or high (7-10) Nugent score, i.e. bacterial vaginosis (BV). Immune biomarker concentrations in cervical swabs were analyzed by generalized linear and mixed effect models adjusting for site, age, hormonal contraceptive use (HC), pregnancy, breastfeeding, genital practices, unprotected sex and overlapping infections. High likelihood ratios (1.5-4.9) denoted the values of cervical immune biomarkers to predict onset of abnormal Nugent score and candidiasis at the next visits. When controlling for covariates, higher levels of β-defensin-2 were antecedent to BV, CT and HSV-2, lower anti-inflammatory ratio IL-1RA:IL-1β-to intermediate Nugent scores and candida, lower levels of the serine protease inhibitor SLPI-to candida, lower levels of the adhesion molecule ICAM-1 -to TV, and lower levels of the oxidative stress mitigator and endothelial activation marker VEGF-to NG. Changes in innate immunity following onset of dysbiosis and infections were dependent on HC use when controlling for all other covariates. In conclusion, imminent female genital tract dysbiosis or infection can be predicted by distinct patterns of innate immunity. Future research should characterize biotic and abiotic determinants of this pre-existing innate immunity state., Competing Interests: The authors have declared that no competing interests exist.

Abnormalities of methyl-CpG binding protein 2 (Mecp2) cause neurological disorders with metabolic dysfunction; however, its role in adipose tissues remains unclear. Here, we report upregulated Mecp2 in white adipose tissues (WAT) of obese humans, as well as in obese mice and during in vitro adipogenesis. Normal chow-fed adipocyte-specific Mecp2 knockout mice ( Mecp2 Adi KO mice) showed a lean phenotype, with downregulated lipogenic genes and upregulated thermogenic genes that were identified using RNA sequencing. Consistently, the deficiency of Mecp2 in adipocytes protected mice from high-fat diet (HFD)-induced obesity and inhibited in vitro adipogenesis. Furthermore, Mecp2 Adi KO mice showed increased browning under different stimuli, including cold treatment. Mechanistically, Mecp2 bound to the promoter of secretory leukocyte protease inhibitor ( Slpi ) and negatively regulated its expression. Knockdown of Slpi in inguinal WAT of Mecp2 Adi KO mice prevented cold-induced browning. Moreover, recombinant SLPI treatment reduced the HFD-induced obesity via enhancing browning. Together, our results suggest a novel non-central nervous system function of Mecp2 in obesity by suppressing browning, at least partially, through regulating adipokine Slpi., (© 2019 by the American Diabetes Association.)

Airway epithelium is an important site for local vitamin D (VD) metabolism; this can be negatively affected by inflammatory mediators. VD is an important regulator of respiratory host defense, for example, by increasing the expression of hCAP18/LL-37. TGF-β1 is increased in chronic obstructive pulmonary disease (COPD), and known to decrease the expression of constitutive host defense mediators such as secretory leukocyte protease inhibitor (SLPI) and polymeric immunoglobulin receptor (pIgR). VD has been shown to affect TGF-β1-signaling by inhibiting TGF-β1-induced epithelial-to-mesenchymal transition. However, interactions between VD and TGF-β1, relevant for the understanding host defense in COPD, are incompletely understood. Therefore, the aim of the present study was to investigate the combined effects of VD and TGF-β1 on airway epithelial cell host defense mechanisms. Exposure to TGF-β1 reduced both baseline and VD-induced expression of hCAP18/LL-37, partly by increasing the expression of the VD-degrading enzyme CYP24A1. TGF-β1 alone decreased the number of secretory club and goblet cells and reduced the expression of constitutive host defense mediators SLPI, s/lPLUNC and pIgR, effects that were not modulated by VD. These results suggest that TGF-β1 may decrease the respiratory host defense both directly by reducing the expression of host defense mediators, and indirectly by affecting VD-mediated effects such as expression of hCAP18/LL-37., (© 2019 The Author(s) Published by S. Karger AG, Basel.)

Compared to females, males are more susceptible to acute viral and other respiratory tract infections that display greater severity and higher mortality. In contrast, females tend to fare worse with chronic inflammatory diseases. Circulating 17β-estradiol (E2) is a female-specific factor that may influence the progression of human lung diseases. Here we hypothesize that E2 modulates the inflammatory response of monocytes through microRNA (miRNA)-based modulation of secretory leucoprotease inhibitor (SLPI), an antiprotease with immunomodulatory effects. Monocytic cells were treated ± E2, and differentially expressed miRNAs were identified using PCR profiling. Cells were transfected with miRNA mimics or antimiRs and SLPI mRNA and protein levels were quantified. Luciferase activity assay using wildtype and ΔmiR-19a/b-SLPI3'UTR reporter constructs and chromatin immunoprecipitation on E2-treated monocytes were performed. E2 downregulated SLPI and upregulated miR-19 expression in monocytes. Transfection with premiR-19b reduced SLPI mRNA and protein levels and this effect was abrogated using antimiRs against miR-19b. miR-19b directly binds the SLPI 3'UTR. The mechanism responsible for E2-mediated upregulation of miR-19 occurs via increased MIR17HG promoter activity mediated by c-MYC. Overall E2 decreases SLPI expression in human monocytic cells, via changes in miRNA expression and highlights the potential for estrogen to modulate the innate immune system., (© 2019 The Author(s) Published by S. Karger AG, Basel.)

Background: Secretory leukocyte protease inhibitor (SPLI) was a secreted protein which belongs to a member of whey acidic protein four-disulfide core family. In breast cancer (BC) it may inhibit cell proliferation and promote cancer metastasis. In this study, a comprehensive bioinformatics analysis was performed to identify the expression and prognostic value of SLPI in breast cancer., Methods: SLPI expression in breast cancer was analyzed in Oncomine online database, which was subsequently confirmed by quantitative PCR (qPCR) in 18 BC samples and western blotting in 26 BC samples. Breast cancer gene-expression miner v4.1 was used to access the expression level with clinicopathological parameters in breast cancer patients. The prognostic values of SLPI in breast cancer were evaluated using the PrognoScan database., Results: Our results indicated that SLPI was downregulated in breast cancer than in normal tissues. SLPI expression was found to be negatively correlated with estrogen receptor (ER) and progesterone receptor (PR) status. SLPI expression level was decreased in negative basal-like status patients compared with positive basal-like status. Meanwhile, triple-negative breast cancer status positive correlated with SLPI. We confirmed a positive correlation between SLPI and interleukin 17 receptor B (IL17RB) express in breast cancer tissues via oncomine co-expression analysis. Ten proteins: Elastase, Granulin, Lipocalin, Defensin beta 103B, Defensin beta 103A, Tubulin, Heparin-binding EGF-like growth factor, Interleukin 6, Epidermal growth factor, Phospholipid scramblase 1 were determinate interactions with SLPI by STRING., Conclusion: SLPI could as a biomarker to predict the prognosis values of breast cancer. However, further comprehensive study and mining more evidence are needed to clarify our results., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Inflammatory bowel diseases (IBDs) are chronic and relapsing immune disorders that result, or possibly originate, from epithelial barrier defects. Intestinal organoids are a new reliable tool to investigate epithelial response in models of chronic inflammation. We produced organoids from the ulcerative colitis murine model Winnie to explore if the chronic inflammatory features observed in the parental intestine were preserved by the organoids. Furthermore, we investigated if quercetin administration to in vitro cultured organoids could suppress LPS-induced inflammation in wild-type organoids (WT-organoids) and spontaneous inflammation in ulcerative colitis organoids (UC-organoids). Our data demonstrate that small intestinal organoids obtained from Winnie mice retain the chronic intestinal inflammatory features characteristic of the parental tissue. Quercetin administration was able to suppress inflammation both in UC-organoids and in LPS-treated WT-organoids. Altogether, our data demonstrate that UC-organoids are a reliable experimental system for investigating chronic intestinal inflammation and pharmacological responses.

Vascular endothelial cell (EC)-derived factors play an important role in endothelial-cardiomyocyte crosstalk and could save cardiomyocytes (CMs) from injury. The manipulation of endothelial cells to secrete protective factors could enhance cardioprotection. Secretory leukocyte protease inhibitor (SLPI) has been known to protect the heart. The goal of this study was to evaluate the in vitro paracrine protective effect and mechanisms of EC-derived human SLPI on cardiomyocytes subjected to hypoxia/reoxygenation (H/R) injury. Stable endothelial cells overexpressing human SLPI were generated from an endothelial cell line (EA.hy926). The cytoprotective effect was determined by cell survival assay. The results showed that endothelial-derived recombinant human SLPI (rhSLPI) reduced simulated ischemia/reperfusion (I/R)-(81.75% ± 1.42% vs. 60.27% ± 2.52%, p < 0.05) and hypoxia/reoxygenation (H/R)-induced EC injury (83.57% ± 1.78% vs. 63.07% ± 1.93%, p < 0.05). Moreover, co-culture of ECs overexpressing rhSLPI with CMs at ratios 1:1 and 1:3 or treatment with conditioned medium enhanced cell viability by 10.51-16.7% (co-culture) and 15.25-20.45% (conditioned medium) by reducing intracellular reactive oxygen species (ROS) production, the Bax/Bcl-2 expression ratio, caspase-3, and caspase-8, and in preconditioned CMs by activation of p38 MAPK and Akt survival kinase. In conclusion, this study showed for the first time that EC-derived rhSLPI provided cardio-vasculoprotective effects against I/R injury as a possible alternative therapeutic strategy for cardioprotection., Competing Interests: The authors declare that they have no conflicts of interest.

Aim: It is important to find biomarkers that identify the graft quality in kidney transplantation. Results & methodology: The level of SLPI in the cold preservation solution was used as a marker to predict early kidney graft function after transplantation. Before transplantation, kidneys were washed and SLPI was measured in the discarded solution. A retrospective analysis showed that patients with delayed graft function or rejection episodes in post-trasplant, had higher SLPI concentrations in the perfusion solution than patients without delayed graft function or rejections. Furthermore, SLPI could discriminate between patients with better or worse estimated glomerular filtration rate among low-risk patients (kidney donor profile index <80). Discussion & conclusion: These results suggest that the SLPI concentration in the perfusion solutions could be a predictor of short-term organ function and a complement to the kidney donor profile index score.

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy, with growing incidence every year. microRNAs (miRs) are known to regulate the physiological and pathological processes of cancers, such as proliferation, migration, invasion, survival, and epithelial-mesenchymal transition (EMT). Herein, this study aimed to investigate the effect of miR-539 on cell proliferation, apoptosis, and EMT by targeting secretory leukocyte protease inhibitor (SLPI) via the transforming growth factor β1 (TGF-β1)/Smads signaling pathway in PTC. First, PTC-related differentially expressed genes and regulatory miR were screened using bioinformatics analysis, dual luciferase reporter gene assay, and ribonucleoprotein immunoprecipitation, which identified the SLPI gene and the regulatory miR-539 for this study. We identified SLPI as a highly expressed gene in PTC tissues, and SLPI was targeted and negatively regulated by miR-539. Then, we introduced a series of miR-539 mimics, miR-539 inhibitors, and small interfering RNA against SLPI plasmids into CGTHW-3 cells to examine the effects of miR-539 and SLPI on the expression of TGF-β1/Smads signaling pathway-, EMT-, and apoptosis-related factors, as well as cell proliferation, migration, invasion, and apoptosis. The obtained results indicated that CGTHW-3 cells treated with silenced SLPI or overexpressed miR-539 suppressed the cell proliferation, migration, invasion abilities, and resistance to apoptosis of PTC cells, corresponding to increased expression of Bcl-2-associated X protein, TGF-β1, Sekelsky mothers against dpp 4, and epithelial cadherin, and decreased B cell lymphoma 2, Vimentin, and N-cadherin. Altogether, we concluded that overexpressed miR-539 could inhibit the PTC cell proliferation and promote apoptosis and EMT by targeting SPLI via activation of the TGF-β1/Smads signaling pathway., (© 2019 Wiley Periodicals, Inc.)

Interleukin-1β (IL-1β) is a potent, pro-inflammatory cytokine of the innate immune system that plays an essential role in host defense against infection. However, elevated circulating levels of IL-1β can cause life-threatening systemic inflammation. Hence, mechanisms controlling IL-1β maturation and release are of outstanding clinical interest. Secretory leukocyte protease inhibitor (SLPI), in addition to its well-described anti-protease function, controls the expression of several pro-inflammatory cytokines on the transcriptional level. In the present study, we tested the potential involvement of SLPI in the control of ATP-induced, inflammasome-dependent IL-1β maturation and release. We demonstrated that SLPI dose-dependently inhibits the ATP-mediated inflammasome activation and IL-1β release in human monocytic cells, without affecting the induction of pro-IL-1β mRNA by LPS. In contrast, the ATP-independent IL-1β release induced by the pore forming bacterial toxin nigericin is not impaired, and SLPI does not directly modulate the ion channel function of the human P2X 7 receptor heterologously expressed in Xenopus laevis oocytes. In human monocytic U937 cells, however, SLPI efficiently inhibits ATP-induced ion-currents. Using specific inhibitors and siRNA, we demonstrate that SLPI activates the calcium-independent phospholipase A2β (iPLA2β) and leads to the release of a low molecular mass factor that mediates the inhibition of IL-1β release. Signaling involves nicotinic acetylcholine receptor subunits α7, α9, α10, and Src kinase activation and results in an inhibition of ATP-induced caspase-1 activation. In conclusion, we propose a novel anti-inflammatory mechanism induced by SLPI, which inhibits the ATP-dependent maturation and secretion of IL-1β. This novel signaling pathway might lead to development of therapies that are urgently needed for the prevention and treatment of systemic inflammation.