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Abstract Cervicovaginal fluid has an important function in the homeostasis and immunity of the lower female genital tract. Analysis of the cervicovaginal fluid proteome may therefore yield important information about the pathogenesis of numerous gynecological pathologies. Additionally, cervicovaginal fluid has great potential as a source of biomarkers for these conditions. This review provides a detailed discussion about the human cervicovaginal proteome and the proteomics studies performed to characterize this biological fluid. Furthermore, infection-correlated pathological conditions of the female genital tract are discussed for which cervicovaginal fluid has been used in order to identify potential biomarkers. Recent years, numerous studies have analyzed cervicovaginal fluid samples utilizing antibody-based technologies, such as ELISA or Western blotting, to identify biomarkers for preterm birth, premature preterm rupture of membranes, bacterial vaginosis and cervical cancer. The present article will discuss the importance of proteomic technologies as alternative techniques to gain additional meaningful information about these conditions. In addition, the review focuses on recent proteomic studies on cervicovaginal fluid samples for the identification of potential biomarkers. We conclude that the use of proteomic technology for analysis of human cervicovaginal fluid samples is promising and may lead to the discovery of new biomarkers which can improve disease prevention and therapy development.

Abstract Background Cervical-vaginal fluid (CVF) plays an important role in the prevention of gynecological infections, although little is known about the contribution of CVF proteins to the immunity of the lower female genital tract. In order to analyze the protein composition of human CVF, we used CVF samples that are routinely collected during colposcopy, but are usually discarded. Since these samples are available in large quantities we aimed to analyze their usefulness for proteomics experiments. The samples were analyzed using different prefractionation techniques (ultrafiltration and C4(RP)-LC protein separation) followed by C18(RP)-LC peptide separation and identification by MALDI-TOF-TOF mass spectrometry. To determine the reproducibility of this proteomics platform we analyzed three technical replicates. Using spectral counting, protein abundances were estimated in a semiquantitative way. We also compared the results obtained in this study with those from previous studies derived from patients with different physiological conditions in order to determine an overlapping protein set. Results In total, we were able to identify 339 proteins in human CVF of which 151 proteins were not identified in any other proteomics study on human CVF so far. Those included antimicrobial peptides, such as human beta-defensin 2 and cathelicidin, which were known to be present in CVF, and endometrial proteins such as glycodelin and ribonucleoprotein A. Comparison of our results with previously published data led to the identification of a common protein set of 136 proteins. This overlapping protein set shows increased fractions of immunological and extracellular proteins, confirming the extracellular immunological role of CVF. Conclusion We demonstrated here that CVF colposcopy samples can be used in proteomics experiments and hence are applicable for biomarker discovery experiments. The delineation of an overlapping set of proteins that is identified in most proteomics studies on CVF may help in the description of a reference proteome when performing proteomics studies on human CVF.

Identifying the potential presence of stress at the pig farm is fundamental since it affects pig welfare. As a result, a reliable and straightforward tool to monitor stress could record the welfare status of the animals. Although numerous methods to assess the welfare of pigs have been developed in the past, no gold standard has been established yet. Recently, the value of saliva as a tool to identify chronic stress in piglets was explored, as it can be collected fast and non-invasively. Since the protein composition, i.e., the proteome of porcine saliva, responds to stress, the affected proteins could be used as salivary stress biomarkers. The present review first defines stress and its relationship with welfare. Next, the porcine gland-specific salivary proteome is characterized. Finally, six potential salivary biomarkers for stress are proposed, i.e., odorant-binding protein, vomeromodulin-like protein, chitinase, lipocalin-1, long palate lung and nasal epithelium protein, and alpha-2-HS-glycoprotein.

Monitoring chronic stress in pigs is not only essential in view of animal welfare but is also important for the farmer, given that stress influences the zootechnical performance of the pigs and increases their susceptibility to infectious diseases. To investigate the use of saliva as a non-invasive, objective chronic stress monitoring tool, twenty-four 4-day-old piglets were transferred to artificial brooders. At the age of 7 days, they were assigned to either the control or the stressed group and reared for three weeks. Piglets in the stressed group were exposed to overcrowding, absence of cage enrichment, and frequent mixing of animals between pens. Shotgun analysis using an isobaric labelling method (iTRAQ) for tandem mass spectrometry performed on saliva samples taken after three weeks of chronic stress identified 392 proteins, of which 20 proteins displayed significantly altered concentrations. From these 20 proteins, eight were selected for further validation using parallel reaction monitoring (PRM). For this validation, saliva samples that were taken one week after the start of the experiment and samples that were taken at the end of the experiment were analysed to verify the profile over time. We wanted to investigate whether the candidate biomarkers responded fast or rather slowly to the onset of chronic exposure to multiple stressors. Furthermore, this validation could indicate whether age influenced the baseline concentrations of these salivary proteins, both in healthy and stressed animals. This targeted PRM analysis confirmed that alpha-2-HS-glycoprotein was upregulated in the stressed group after one and three weeks, while odorant-binding protein, chitinase, long palate lung and nasal epithelium protein 5, lipocalin-1, and vomeromodulin-like protein were present in lower concentrations in the saliva of the stressed pigs, albeit only after three weeks. These results indicate that the porcine salivary proteome is altered by chronic exposure to multiple stressors. The affected proteins could be used as salivary biomarkers to identify welfare problems at the farm and facilitate research to optimise rearing conditions., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Prims et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Aims: To evaluate the prevalence and type of adverse drug reactions (ADRs), together with associated risk factors, among Cuban COVID-19 patients treated with chloroquine (CQ), lopinavir/ritonavir (LPV/r), or interferon α 2b (IFN α 2b), according to the Cuban protocol., Materials and Methods: A prospective descriptive analysis of ADRs was performed on 200 COVID-19 patients who were admitted consecutively to three hospitals in Havana and Pinar del Río from April to July 2020. Information on demographics, ADRs, outcomes, behavioral, and health-related factors was collected using a validated questionnaire and clinical records. Each potential ADR case was assessed for causality based on the WHO-UMC algorithm, concomitant drug influences, and the presence of any drug-drug interactions (DDI)., Results: The total frequency of ADRs was 55%, with predominantly gastrointestinal disorders and general symptoms (23% vs 20%). 95.1% of ADRs occurred within 10 days after treatment and 42 potential DDI in 55.5% of patients (61/110) were observed. The prevalence of ADRs was: 44%, 30.4%, and 26.4% for IFN α 2b, LPV/r, and CQ, respectively. Sex (odds ratio (OR): 0.40 (95% confidence interval (CI): 0.211-0.742), age (OR: 2.36 (95% CI: 1.02-5.44)), and underlying diseases (OR: 0.12 (95% CI: 0.06-0.23)) were independently associated factors for ADRs ( P < 0.05)., Conclusions: The frequency of ADRs and potential DDI was high compared to their use during nonpandemic times (e.g., for malaria, HIV, or inflammatory diseases). The safety profile of these drugs when used for COVID-19 treatment showed similar characteristics. Comorbidities, age >37 years old, and female sex were associated with ADRs., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2023 Lizette Gil-del-Valle et al.)

Host cell DNA methylation analysis in urine provides promising triage markers for women diagnosed with a high-risk (HR) human papillomavirus (HPV) infection. In this study, we have investigated a panel of six host cell methylation markers (GHSR, SST, ZIC1, ASCL1, LHX8, ST6GALNAC5) in cervicovaginal secretions collected within the first part of the urine void (FVU) from a referral population. Cytology, histology, and HPV DNA genotyping results on paired FVU and cervical samples were available. Urinary median methylation levels from HR-HPV (n = 93) positive women were found to increase for all markers with severity of underlying disease. Significantly elevated levels were observed for GHSR and LHX8 in relation to high-grade cervical intraepithelial neoplasia (CIN2 +; n = 33), with area under de curve values of 0.80 (95% Confidence Interval (CI) 0.59-0.92) and 0.76 (95% CI 0.58-0.89), respectively. These findings are the first to support the assertion that methylation analysis of host cell genes is feasible in FVU and holds promise as molecular, triage strategy to discern low- from high-grade cervical disease in HR-HPV positive women. Molecular testing on FVU may serve to increase cervical cancer screening attendance in hard-to-reach populations whilst reducing loss to follow-up and await further optimization and validation studies.

Multiple myeloma (MM) is a hematological malignancy characterized by plasma cells' uncontrolled growth. The major barrier in treating MM is the occurrence of primary and acquired therapy resistance to anticancer drugs . Often, this therapy resistance is associated with constitutive hyperactivation of tyrosine kinase signaling. Novel covalent kinase inhibitors, such as the clinically approved BTK inhibitor ibrutinib (IBR) and the preclinical phytochemical withaferin A (WA), have, therefore, gained pharmaceutical interest. Remarkably, WA is more effective than IBR in killing BTK-overexpressing glucocorticoid (GC)-resistant MM1R cells. To further characterize the kinase inhibitor profiles of WA and IBR in GC-resistant MM cells, we applied phosphopeptidome- and transcriptome-specific tyrosine kinome profiling. In contrast to IBR, WA was found to reverse BTK overexpression in GC-resistant MM1R cells. Furthermore, WA-induced cell death involves covalent cysteine targeting of Hinge-6 domain type tyrosine kinases of the kinase cysteinome classification, including inhibition of the hyperactivated BTK. Covalent interaction between WA and BTK could further be confirmed by biotin-based affinity purification and confocal microscopy. Similarly, molecular modeling suggests WA preferably targets conserved cysteines in the Hinge-6 region of the kinase cysteinome classification, favoring inhibition of multiple B-cell receptors (BCR) family kinases. Altogether, we show that WA's promiscuous inhibition of multiple BTK family tyrosine kinases represents a highly effective strategy to overcome GC-therapy resistance in MM.

Chikungunya virus (CHIKV) is an arbovirus with a global spread and significant public health impact. It is a positive stranded RNA alphavirus belonging to the Togaviridae family. However, many questions about the replication cycle of CHIKV remain unanswered. The entry process of CHIKV is not completely understood nor are the associated virus-receptor interactions fully identified. Here, we designed an affinity purification mass spectrometry coupled approach that allowed the identification of factors that facilitate entry of CHIKV in human cells. The identified entry factors were further validated using CRISPR/Cas9. In HEK293T cells we identified the CD147 protein complex as an entry factor for CHIKV. We further showed the involvement of the CD147 protein complex in the replication cycle of related alphaviruses. Interestingly, CD147 contains similar protein domains as the previously identified alphavirus entry factor MXRA8., 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 © 2021 De Caluwé, Coppens, Vereecken, Daled, Dhaenens, Van Ostade, Deforce, Ariën and Bartholomeeusen.)

The direct agglutination test (DAT) for visceral leishmaniasis (VL) is the serodiagnostic test for VL that has the most robust sensitivity and specificity in the field across all endemic regions. It is based on trypsin-treated and formaldehyde-fixed whole promastigote cells from Leishmania donovani . The exact identity and nature of the epitopes on the DAT antigen that cause agglutination with VL patients' sera are currently unknown. In this study, we performed antigen-inhibition studies which revealed that lipophosphoglycan (LPG) and the DAT antigen share epitopes. Antibody inhibition with a monoclonal antibody directed against the phosphoglycan repeat epitope of LPG showed that this is not the epitope that reacts with human sera. Oxidation of carbohydrates by sodium metaperiodate did not alter the reactivity of human sera with the DAT antigen and LPG. This indicates that carbohydrates do not play a role in the reaction of the DAT antigen with antibodies in serum from VL patients, and that they also are not involved in the reaction of LPG with the same serum. We conclude that the noncarbohydrate moiety of LPG, that is, the core-anchor fragment, and potentially other noncarbohydrate epitopes on the surface of the DAT antigen are responsible for its agglutination with antibodies from VL patients. As LPG plays a role in the DAT reaction, this could facilitate the following: 1) incorporation of LPG, preferably the synthetic version of the core-anchor fragment, into an immunochromatographic test format that is more adapted as a point-of-care test (short incubation, little training, and equipment needed) than DAT and 2) enhancing the quality control for the production of the DAT antigen.

Background: Genital infection with certain types of Human papillomavirus (HPV) is a major cause of cervical cancer globally. For early detection of premalignant dysplasia, evidences are coming out on the usefulness of HPV E6/E7 mRNA test as a potential tool compared with cytology and HPV DNA testing. Taking into account shortage of compiled data on this field, the aim of this systematic review was to describe the latest diagnostic performance of HPV E6/E7 mRNA testing to detect high grade cervical lesions (CIN2+) where by histology was taken as a gold standard., Methods: Articles published in English were systematically searched using key words from PubMed/Medline and SCOPUS. In addition, Google Scholar and the Google database were searched manually for grey literature. Two reviewers independently assessed study eligibility, risk of bias and extracted the data. We performed a descriptive presentation of the performance of E6/E7 mRNA test (in terms of sensitivity, specificity, negative and positive predictive values) for the detection of CIN2 + ., Results: Out of 231 applicable citations, we have included 29 articles that included a total of 23,576 study participants (age range, 15-84 years) who had different cervical pathologies. Among the participants who had cervical histology, the proportion of CIN2+ was between 10.6 and 90.6%. Using histology as a gold standard, 11 studies evaluated the PreTect HPV Proofer, 7 studies evaluated the APTIMA HPV assay (Gen-Probe) and 6 studies evaluated the Quantivirus® HPV assay. The diagnostic performance of these three most common mRNA testing tools to detect CIN2+ was; 1) PreTect Proofer; median sensitivity 83%, specificity 73%, PPV 70 and NPV 88.9%. 2) APTIMA assay; median sensitivity 91.4%, specificity 46.2%, PPV 34.3% and NPV 96.3%. 3) Quantivirus®: median sensitivity 86.1%, specificity 54.6%, PPV 54.3% and NPV was at 89.3%. Further, the area under the receiver operating characteristics (AU-ROC) curve varied between 63.8 and 90.9%., Conclusions: The reported diagnostic accuracy implies that HPV mRNA based tests possess diagnostic relevance to detect CIN2+ and could potentially be considered in areas where there is no histology facility. Further studies including its cost should be considered., Competing Interests: Competing interestsThe authors declare that they have no competing interests., (© The Author(s). 2020.)

Over 99% of cervical cancer cases are associated with genital infection by certain types of human papillomaviruses (HPVs). To outline optimal vaccination strategies and HPV based cervical cancer screening, synthesized data on the genotype distribution of HPV is fundamental that is otherwise missed in Ethiopia. The aim of this study is to compile the findings on HPV genotyping in Ethiopia. Published articles were systematically searched using comprehensive search strings from PubMed/Medline and SCOPUS. Further, Google Scholar and the Google databases were also searched manually for grey literature. The included studies in the review employed 859 women (age range 15-85 years) with different kinds of cervical abnormalities. A total of 534 HPV sequences were reported; the proportion of high risk HPVs was varied 80.4-100%. The top five identified genotypes were HPV 16 (45.3%; 95% CI 41.1-49.6%), HPV 52 (9.4%; 95% CI 7.2-12.1%), HPV 18 (8.2%; 95% CI 6.2-10.9%), HPV 58 (6.9%; 95% CI 5.1-9.4%) and HPV 45 (5.2%; 95% CI 3.7-7.5%). The combined prevalence of HPV 16/18 was at 53.6% (95% CI 49.3-57.8%). In this review, HPV 16 in particular, but also HPV 52 and 18, warrant exceptional consideration in vaccination and HPV based screening programs in Ethiopia. To the best of our knowledge, this study represents the first of its kind to establish the genotype distribution of HPV from different kinds of cervical lesions in Ethiopia although it was synthesized out of few studies. Hence, additional nationwide data are needed to strengthen our finding.

Background: Current syphilis diagnostic strategies are lacking a sensitive manner of directly detecting Treponema pallidum antigens. A diagnostic test that could directly detect T. pallidum antigens in individuals with syphilis would be of considerable clinical utility, especially for the diagnosis of reinfections and for post-treatment serological follow-up. Methods: In this study, 11 candidate T. pallidum biomarker proteins were chosen according to their physiochemical characteristics, T. pallidum specificity and predicted abundance. Thirty isotopically labelled proteotypic surrogate peptides (hPTPs) were synthesized and incorporated into a scheduled multiple reaction monitoring assay. Protein extracts from undepleted/unenriched plasma (N = 18) and urine (N = 4) samples from 18 individuals with syphilis in various clinical stages were tryptically digested, spiked with the hPTP mixture and analysed with a triple quadruple mass spectrometer. Results: No endogenous PTPs corresponding to the eleven candidate biomarkers were detected in any samples analysed. To estimate the Limit of Detection (LOD) of a comparably sensitive mass spectrometer (LTQ-Orbitrap), two dilution series of rabbit cultured purified T. pallidum were prepared in PBS. Polyclonal anti- T. pallidum antibodies coupled to magnetic Dynabeads were used to enrich one sample series; no LOD improvement was found compared to the unenriched series. The estimated LOD of MS instruments is 300 T. pallidum /ml in PBS. Conclusions: Biomarker protein detection likely failed due to the low (femtomoles/liter) predicted concentration of T. pallidum proteins. Alternative sample preparation strategies may improve the detectability of T. pallidum proteins in biofluids., Competing Interests: No competing interests were disclosed.

Synthetic glucocorticoids (GC) are the mainstay therapy for treatment of acute and chronic inflammatory disorders. Due to the high adverse effects associated with long-term use, GC pharmacology has focused since the nineties on more selective GC ligand-binding strategies, classified as selective glucocorticoid receptor (GR) agonists (SEGRAs) or selective glucocorticoid receptor modulators (SEGRMs). In the current study, GSK866 analogs with electrophilic covalent-binding warheads were developed with potential SEGRA properties to improve their clinical safety profile for long-lasting topical skin disease applications. Since the off-rate of a covalently binding drug is negligible compared to that of a non-covalent drug, its therapeutic effects can be prolonged and typically, smaller doses of the drug are necessary to reach the same level of therapeutic efficacy, thereby potentially reducing systemic side effects. Different analogs of SEGRA GSK866 coupled to cysteine reactive warheads were characterized for GR potency and selectivity in various biochemical and cellular assays. GR- and NFκB-dependent reporter gene studies show favorable anti-inflammatory properties with reduced GR transactivation of two non-steroidal GSK866 analogs UAMC-1217 and UAMC-1218, whereas UAMC-1158 and UAMC-1159 compounds failed to modulate cellular GR activity. These results were further supported by GR immuno-localization and S211 phospho-GR western analysis, illustrating significant GR phosphoactivation and nuclear translocation upon treatment of GSK866, UAMC-1217, or UAMC-1218, but not in case of UAMC-1158 or UAMC-1159. Furthermore, mass spectrometry analysis of tryptic peptides of recombinant GR ligand-binding domain (LBD) bound to UAMC-1217 or UAMC-1218 confirmed covalent cysteine-dependent GR binding. Finally, molecular dynamics simulations, as well as glucocorticoid receptor ligand-binding domain (GR-LBD) coregulator interaction profiling of the GR-LBD bound to GSK866 or its covalently binding analogs UAMC-1217 or UAMC-1218 revealed subtle conformational differences that might underlie their SEGRA properties. Altogether, GSK866 analogs UAMC-1217 and UAMC-1218 hold promise as a novel class of covalent-binding SEGRA ligands for the treatment of topical inflammatory skin disorders.

Despite the worldwide research efforts to combat cancer, it remains a leading cause of death. Although various specific kinase inhibitors already have been approved for clinical cancer treatment, occurrence of intrinsic or acquired resistance and intermittent response over longer periods limits long-term success of single kinase-targeted therapies. In this respect, there is a renewed interest in polypharmaceutical natural compounds, which simultaneously target various hyperactivated kinases involved in tumour-inflammation, angiogenesis, cell survival, proliferation, metastasis and angiogenesis. The dietary medicinal phytochemical withaferin A (WA), isolated from Withaferin somnifera (popular Indian name Ashwagandha), holds promise as a novel anti-cancer agent, which targets multiple cell survival kinase pathways, including IκB kinase/NF-κB, PI3 kinase/protein kinase B/mammalian target of rapamycin and mitogen-activated protein kinase/extracellular signal-regulated kinase amongst others. In this review, we propose a novel mechanism of WA-dependent kinase inhibition via electrophilic covalent targeting of cysteine residues in conserved kinase activation domains (kinase cysteinome), which could underlie its pleiotropic therapeutic effects in cancer signalling.

Background: The spirochete bacterium Treponema pallidum ssp. pallidum is the etiological agent of syphilis, a chronic multistage disease. Little is known about the global T. pallidum proteome, therefore mass spectrometry studies are needed to bring insights into pathogenicity and protein expression profiles during infection., Methodology/principal Findings: To better understand the T. pallidum proteome profile during infection, we studied T. pallidum ssp. pallidum DAL-1 strain bacteria isolated from rabbits using complementary mass spectrometry techniques, including multidimensional peptide separation and protein identification via matrix-assisted laser desorption ionization-time of flight (MALDI-TOF/TOF) and electrospray ionization (ESI-LTQ-Orbitrap) tandem mass spectrometry. A total of 6033 peptides were detected, corresponding to 557 unique T. pallidum proteins at a high level of confidence, representing 54% of the predicted proteome. A previous gel-based T. pallidum MS proteome study detected 58 of these proteins. One hundred fourteen of the detected proteins were previously annotated as hypothetical or uncharacterized proteins; this is the first account of 106 of these proteins at the protein level. Detected proteins were characterized according to their predicted biological function and localization; half were allocated into a wide range of functional categories. Proteins annotated as potential membrane proteins and proteins with unclear functional annotations were subjected to an additional bioinformatics pipeline analysis to facilitate further characterization. A total of 116 potential membrane proteins were identified, of which 16 have evidence supporting outer membrane localization. We found 8/12 proteins related to the paralogous tpr gene family: TprB, TprC/D, TprE, TprG, TprH, TprI and TprJ. Protein abundance was semi-quantified using label-free spectral counting methods. A low correlation (r = 0.26) was found between previous microarray signal data and protein abundance., Conclusions: This is the most comprehensive description of the global T. pallidum proteome to date. These data provide valuable insights into in vivo T. pallidum protein expression, paving the way for improved understanding of the pathogenicity of this enigmatic organism., Competing Interests: The authors have declared that no competing interests exist.

Despite large gaps in our knowledge on the intracellular mechanism leading to cervical cancer, the pathways induced by oncogenic high-risk Human Papilloma Virus (HPV) and those finally causing cervical cancer are increasingly being unraveled. Assuming that precancerous tissue is recognized and lysed by the immune system-which is in many cases incomplete because of the counteraction by the HPV virus-we hypothesize that several intracellular factors, involved in induction and development of precancerous lesions and/or cervical cancer are being released into the cervicovaginal fluid (CVF). These factors can then be seen as markers for the precancerous state, and when they persist they are indicative for an increased risk for cervical carcinoma. In a previous study, we analyzed the proteomic profiles of six CVF samples from women with different stages of precancerous lesions and compared these with the CVF proteomes from healthy women. Here, we extend these observations by investigating these proteomes by Ingenuity Pathway Analysis (IPA). We show that proteins in CVF from precancerous women are clearly more involved in pathways that make up the 'hallmarks of cancer', as compared to CVF proteins from healthy persons. Moreover, after literature search, proteins classified by IPA in the 'cancer' category, were more correlated with cervical cancer when they originated from CVF from precancerous women. Many of these proteins formed a network with angiotensin II as central mediator. The search for 'network biomarkers', rather than single biomarkers, could drastically increase specificity, sensitivity and prognostic value of cervical cancer diagnosis, making use of an easy to handle fluid, the CVF.

HIV-exposed seronegative individuals (HESNs) are persons who remain seronegative despite repeated exposure to HIV, suggesting an in vivo resistance mechanism to HIV. Elucidation of endogenous factors responsible for this phenomenon may aid in the development of new classes of microbicides and therapeutics. We compared cervicovaginal protein abundance profiles between high-risk HESN and two control groups: low-risk HESN and HIV-positives. Four iTRAQ-based quantitative experiments were performed using samples classified based on presence/absence of particular gynaecological conditions. After statistical analysis, two proteins were shown to be differentially abundant between high-risk HESNs and control groups. Serpin A5, a serine proteinase inhibitor and Myeloblastin, a serine protease, were up- and downregulated, respectively. Commercially available ELISA assays were used to confirm differential Serpin A5 levels. These results suggest that HIV resistance in CVF of HESNs is the result of a delicate balance between two complementary mechanisms: downregulation of serine proteinases and upregulation of their inhibitors., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: HIV-1 replication depends on a delicate balance between cellular co-factors and antiviral restriction factors. Lens epithelium-derived growth factor (LEDGF/p75) benefits HIV, whereas apolipoprotein B mRNA-editing catalytic polypeptide-like 3G (APOBEC3G), tripartite motif 5alpha (TRIM5α), and tetherin exert anti-HIV activity. Expression levels of these proteins possibly contribute to HIV-1 resistance in HIV-1-exposed populations., Methodology/principal Findings: We used real-time PCR and flow cytometry to study mRNA and protein levels respectively in PBMC and PBMC subsets. We observed significantly reduced LEDGF/p75 protein levels in CD4+ lymphocytes of HIV-1-exposed seronegative subjects relative to healthy controls, whereas we found no differences in APOBEC3G, TRIM5α, or tetherin expression. Untreated HIV-1-infected patients generally expressed higher mRNA and protein levels than healthy controls. Increased tetherin levels, in particular, correlated with markers of disease progression: directly with the viral load and T cell activation and inversely with the CD4 count., Conclusions/significance: Our data suggest that reduced LEDGF/p75 levels may play a role in resistance to HIV-1 infection, while increased tetherin levels could be a marker of advanced HIV disease. Host factors that influence HIV-1 infection and disease could be important targets for new antiviral therapies.

We examined the interaction of ECM1 (extracellular matrix protein 1) using yeast two-hybrid screening and identified the type II transmembrane protein, PLSCR1 (phospholipid scramblase 1), as a binding partner. This interaction was then confirmed by in vitro and in vivo co-immunoprecipitation experiments, and additional pull-down experiments with GST-tagged ECM1a fragments localized this interaction to occur within the tandem repeat region of ECM1a. Furthermore, immunohistochemical staining revealed a partial overlap of ECM1 and PLSCR1 in human skin at the basal epidermal cell layer. Moreover, in human skin equivalents, both proteins are expressed at the basal membrane in a dermal fibroblast-dependent manner. Next, immunogold electron microscopy of ultrathin human skin sections showed that ECM1 and PLSCR1 co-localize in the extracellular matrix, and using antibodies against ECM1 or PLSCR1 cross-linked to magnetic immunobeads, we were able to demonstrate PLSCR1-ECM1 interaction in human skin extracts. Furthermore, whereas ECM1 is secreted by the endoplasmic/Golgi-dependent pathway, PLSCR1 release from HaCaT keratinocytes occurs via a lipid raft-dependent mechanism, and is deposited in the extracellular matrix. In summary, we here demonstrate that PLSCR1 interacts with the tandem repeat region of ECM1a in the dermal epidermal junction zone of human skin and provide for the first time experimental evidence that PLSCR1 is secreted by an unconventional secretion pathway. These data suggest that PLSCR1 is a multifunctional protein that can function both inside and outside of the cell and together with ECM1 may play a regulatory role in human skin.

Promyelocytic Leukaemia Protein nuclear bodies (PML-NBs) are dynamic nuclear protein aggregates. To gain insight in PML-NB function, reductionist and high throughput techniques have been employed to identify PML-NB proteins. Here we present a manually curated network of the PML-NB interactome based on extensive literature review including database information. By compiling 'the PML-ome', we highlighted the presence of interactors in the Small Ubiquitin Like Modifier (SUMO) conjugation pathway. Additionally, we show an enrichment of SUMOylatable proteins in the PML-NBs through an in-house prediction algorithm. Therefore, based on the PML network, we hypothesize that PML-NBs may function as a nuclear SUMOylation hotspot.

In contrast to the large number of class I and II cytokine receptors, only four Janus kinase (Jak) proteins are expressed in mammalian cells, implying the shared use of these kinases by many different receptor complexes. Consequently, if receptor numbers exceed the amount of available Jak, cross-interference patterns can be expected. We have engineered two model cellular systems expressing two different exogenous Tyk2-interacting receptors. A receptor chimera was generated wherein the extracellular part of the interferon type 1 receptor (Ifnar1) component of the interferon-alpha/beta receptor is replaced by the equivalent domain of the erythropoietin receptor. Despite Tyk2 activation, erythropoietin treatment of cells expressing this erythropoietin receptor/Ifnar1 chimera did not evoke any detectable IFN-type response. However, a dose-dependent interference with signal transduction via the endogenous Ifnar complex was found for STAT1, STAT2, STAT3, Tyk2, and Jak1 activation, for gene induction, and for antiviral activity. In a similar approach, cells expressing the beta1 chain of the interleukin-12 receptor showed a reduced transcriptional response to IFN-alpha as well as reduced STAT and kinase activation. In both model systems, titration of the Tyk2 kinase away from the Ifnar1 receptor chain accounts for the observed cross-interference.

The human interleukin-5 (IL-5) receptor consists of an alpha-chain that specifically binds the ligand with intermediate affinity, and a beta c-chain, that associates with the IL-5/IL-5R alpha complex, leading to a high-affinity, signal transducing receptor complex. Structure-function studies showed that modification of the putative beta c-chain binding site in IL-5 (E13Q mutein) converted the molecule into an antagonist. However, analysis of the effect of this mutant IL-5 on COS-1 cells transfected with both receptor subunits, did not show reduced interaction with the beta c subunit [Tavernier, J., Tuypens, T., Verhee, A., Plaetinck, G., Devos, R., Van der Heyden, J., Guisez, Y. & Oefner, C. (1995) Proc. Natl Acad. Sci. USA 89, 7041-7045]. To gain more insight into the mechanism of IL-5 antagonism by E13Q, we tested its biological activity on two FDC-P1 subclones that express clearly different numbers of alpha-subunits yet an almost constant number of murine beta c-subunits. Here we show that E13Q has a biological activity comparable to wild-type IL-5 only when a high number of alpha-chains is present on the cells. Confirming the critical role of the IL5R alpha cell-surface expression level, treatment with suboptimal doses of a neutralising anti-IL-5R alpha antibody results in reduced activity of the mutant but not of wild-type IL-5.

Granulocyte apoptosis is an important mechanism underlying the removal of redundant neutrophils from an inflammatory focus. The ability of many proinflammatory agents to impede this event suggests that such agents act not only in a priming or secretagogue capacity but also increase neutrophil longevity by delaying apoptosis. We have examined whether this hypothesis holds true for all neutrophil priming agents, in particular tumor necrosis factor-alpha (TNF-alpha), which has been variably reported to either induce, delay, or have no effect on neutrophil apoptosis. After 20 hours coincubation TNF-alpha inhibited neutrophil apoptosis; however, more detailed analysis demonstrated its ability to promote apoptosis in a subpopulation of cells at earlier (2 to 8 hours) times. Formyl-Met-Leu-Phe, platelet-activating factor, inositol hexakisphosphate, lipopolysaccharide, leukotriene B4, and granulocyte-macrophage colony-stimulating factor all inhibited apoptosis at 6 and 20 hours. The early proapoptotic effect of TNF-alpha was concentration-dependent (EC50 2.8 ng/mL), abolished by TNF-alpha neutralizing antibody, and was not associated with any change in cell viability or recovery. Of relevance to the inflamed site, the ability of TNF-alpha to accelerate apoptosis was lost if neutrophils were primed with 1 micromol/L PAF or aged for 6 hours before TNF-alpha addition. The TNFR55-selective TNF-alpha mutants (E146K, R32W-S86T) induced neutrophil apoptosis but with a potency 14-fold lower than wild-type TNF-alpha. Although the TNFR75-selective mutant (D143F) did not induce apoptosis, blocking antibodies to both receptor subtypes abolished TNF-alpha-stimulated apoptosis. Hence, TNF-alpha has the unique ability to induce apoptosis in human neutrophils via a mechanism where TNFR75 facilitates the dominant TNFR55 death effect. This may be an important mechanism controlling neutrophil longevity and clearance in vivo.

Previously, we reported that the cytotoxic activity of human (h) tumor necrosis factor (TNF) on murine (m) L929 cells requires the integrity of three loops (positions 30-36, 84-88 and 138-150) which cluster around the interface between each two subunits of the trimeric hTNF structure. The collection of hTNF mutants was further characterized by their activity on various human cell systems as well as by their binding to the two types of hTNF receptor (R), R55 and R75. It turned out that two amino acids (Leu29 and Arg32) were specifically involved in hR75 binding, as Leu29-->Ser (L29S) and Arg32-->Trp (R32W) mutant molecules had largely lost binding to hR75, but not to hR55. In order to screen for more highly R55-specific mutants, nine other amino acids were inserted at these two positions; only the substitutions L29G and L29Y showed an increased differential binding as compared to L29S, while no further improvement was found with mutations at position 32 compared to R32W. Biological assays mediated either by hR55 or hR75 confirmed the results obtained by physical binding to purified receptors. A similar substitution in mTNF, Arg32-->Tyr, also resulted in a preferential loss of binding to hR75 and a large decrease in mR75-mediated bioactivity. Except for the double mutant L29S-R32W, all other tested amino acid substitutions in the loops at positions 30-36 or 84-88 of hTNF led to a substantial loss of affinity for both receptors and a concomitant reduction of biological activity. In the loop at positions 138-150, the non-conservative replacement of Glu by Lys at position 146 (E146K) resulted in an even lower binding to R75 as compared to R32W, while binding on and bioactivity through R55 was only slightly reduced. Remarkably, a reversed differential binding was observed after substitution at position 143 in hTNF; replacing Asp by non-conservative residues such as Tyr, Phe or Asn resulted in a much larger decrease in binding to R55 than to R75. In conclusion, receptor-specific mutants such as R32W, E146K and D143N can be used to study the function either of R55 or R75 on different human cell types. In vivo, we presume that the R55-specific mutants will retain antitumor activity in the absence of R75-dependent, severe side effects.

The remarkable ability of tumour necrosis factor (TNF), especially in combination with interferon, selectively to kill or inhibit malignant cell lines is so far unmatched by any other combination of cytokines. But clinical trials in cancer patients have on the whole been disappointing, and it has been estimated that a TNF dose would be effective only at 5-25 times the maximum tolerated dose. High TNF concentrations give a much more pronounced antitumour activity in mice, in which murine TNF is about 50-fold more systemically toxic than human TNF. But there is little or no species specificity in cytotoxicity of murine TNF and human TNF on human as well as on murine cell lines. This dual action of TNF may be explained by the existence of two types of receptor for TNF: the smaller, TNF-R55, is present on most cells and particularly on those susceptible to the cytotoxic action of TNF; the larger, TNF-R75, is also present on many cell types, especially those of myeloid origin, and is strongly expressed on stimulated T and B lymphocytes. In mice, human TNF binds only to murine TNF-R55 (ref. 15), which can then mediate cytotoxic activity on malignant cells. As human TNF does not bind to murine TNF-R75, the latter must be responsible for the much enhanced systemic toxicity of murine TNF. Human TNF can, however, become toxic in mice when a second pathway is activated. There is no reciprocal situation in the human system: human and murine TNF bind almost equally well to the two human TNF receptors. Here we describe human TNF mutants that sill interact with the human TNF-R55 receptor but which have largely lost their ability to bind to human TNF-R75. Activation of TNF-R55 is sufficient to trigger cytotoxic activity towards transformed cells. One representative human TNF mutant retains its antitumour activity in nude mice carrying tumours derived from human cancers. Under the appropriate conditions, such human TNF mutants are expected to induce less systemic toxicity in man, while still exerting their direct antitumour effect.

Each of the two highly conserved tryptophan residues in hTNF (positions 28 and 114) was converted into phenylalanine by site-directed mutagenesis and the mutant proteins were partially purified. A cytotoxicity assay on mouse L929 cells showed only a slight reduction in biological activity, strongly suggesting that neither of the two amino acids is involved in the active site.

Four distinct areas of primary sequence conservation between known tumour necrosis factor and lymphotoxin polypeptides from various species can be recognized. When these amino acid sequences are highlighted in the three-dimensional structure, all are found in the same region, constituting the framework of the trimeric structure.