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Neutrophils represent one of the host's first lines of defense against invading pathogens. However, an aberrant activation can cause damage to the host. In the case of respiratory infections with viral or bacterial pathogens, one of the most common complications is the development of acute respiratory distress syndrome, in which neutrophil infiltration into the lung is a hallmark. Neutrophils gain expression of chemokine receptors under inflammatory conditions, and their activation can amplify the neutrophil responses. Earlier studies showed that neutrophils recruited to the lung mucosa during bacterial infection upregulate expression of CCR3 and ex vivo stimulation of CCR3 results in an increased neutrophil activation. Therefore, the modulation of effector functions or migration of neutrophils to target sites through chemokine receptors constitutes an opportunity for pharmacological intervention. We aimed to determine whether the blockade of the CCR3 using the specific antagonist SB-328437 reduces neutrophil recruitment and inflammation in the lung in the lipopolysaccharide (LPS)-induced lung injury model and influenza infection in mice. We found that neutrophils acquire CCR3 expression in the lung alveolar space. The intraperitoneal administration of SB-328437 reduced neutrophil recruitment to the lung alveolar space and reduced tissue damage in both the LPS-induced lung injury model and influenza infection. Moreover, treatment with SB-328437 reduced the percentage of neutrophils producing TNFα and neutrophil activation in the alveolar space. Together, these data suggest that CCR3 blockade might be a pharmacological strategy to prevent the aberrant neutrophil activation that results detrimental for the host but preserves sufficient effector response to control the pathogen., Competing Interests: Conflict of interest statement. No conflicts of interest are declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Leukocyte Biology.)

Systemic lupus erythematosus (SLE) is an autoimmune disorder that often leads to kidney injury, known as lupus nephritis (LN). Although renal biopsy is the primary way to diagnose LN, it is invasive and not practical for regular monitoring. As an alternative, several groups have proposed urinary extracellular vesicles (uEVs) as potential biomarkers for LN, as recent studies have shown their significance in reflecting kidney-related diseases. As a result, we developed a flow cytometry approach that allowed us to determine that LN patients exhibited a significantly higher total uEV concentration compared to SLE patients without kidney involvement. Additionally, an analysis of different-sized uEV subsets revealed that microvesicles ranging from 0.3 to 0.5 μm showed the most promise for distinguishing LN. These findings indicate that evaluating uEV concentration and size distribution could be a valuable diagnostic and monitoring tool for LN, pending further validation in more comprehensive studies.

The coronavirus disease 2019 (COVID-19) survivors are frequently observed to present persistent symptoms constituting what has been called "post-acute COVID-19 syndrome" (PACS) or "long COVID-19". Some clinical risk factors have been identified to be associated with PACS development; however, specific mechanisms responsible for PACS pathology remain unknown. This study investigates clinical, immunological, and metabolomic risk factors associated with post-acute COVID-19 syndrome (PACS) in 51 patients, assessed 7-19 months after acute infection. Among the participants, 62.7% were male and 37.2% were female, with an average age of 47.8 years. At the follow-up, 37.2% met the criteria for PACS, revealing significant differences in immunological and metabolomic profiles at the time of acute infection. Patients with PACS were characterized by elevated levels of mature low-density granulocytes (LDGs), interleukin-8 (IL-8), pyruvate, pseudouridine, and cystine. Baseline multivariate analysis showed increased pyruvate and decreased alpha tocopherol levels. At follow-up, there was a decrease in absolute B lymphocytes and an increase in non-classical monocytes and 3-hydroxyisovaleric acid levels. These findings suggest that specific immunological and metabolomic markers during acute infection can help identify patients at higher risk of developing persistent PACS.

The chemokine CCL28 is highly expressed in mucosal tissues, but its role during infection is not well understood. Here, we show that CCL28 promotes neutrophil accumulation in the gut of mice infected with Salmonella and in the lung of mice infected with Acinetobacter . Neutrophils isolated from the infected mucosa expressed the CCL28 receptors CCR3 and, to a lesser extent, CCR10, on their surface. The functional consequences of CCL28 deficiency varied between the two infections: Ccl28 -/- mice were highly susceptible to Salmonella gut infection but highly resistant to otherwise lethal Acinetobacter lung infection. In vitro, unstimulated neutrophils harbored pre-formed intracellular CCR3 that was rapidly mobilized to the cell surface following phagocytosis or inflammatory stimuli. Moreover, CCL28 stimulation enhanced neutrophil antimicrobial activity, production of reactive oxygen species, and formation of extracellular traps, all processes largely dependent on CCR3. Consistent with the different outcomes in the two infection models, neutrophil stimulation with CCL28 boosted the killing of Salmonella but not Acinetobacter . CCL28 thus plays a critical role in the immune response to mucosal pathogens by increasing neutrophil accumulation and activation, which can enhance pathogen clearance but also exacerbate disease depending on the mucosal site and the infectious agent., Competing Interests: GW, AP, SS, ML, EB, ND, SB, RG, KM, GN, FA, FD, LP, VS, RC, SR, MC, JM, SN, VN, MR No competing interests declared, (© 2024, Walker, Perez-Lopez et al.)

CRTAM (Class-I MHC restricted T cell-associated molecule) is a member of the Nectin-like family, composed of two extracellular domains, one constant domain (IgC) and another variable domain (IgV), expressed in activated CD8 T cells, epithelial cells, natural killer (NK) cells, and in a subpopulation of CD4 T cells. CRTAM recognizes the ligand Nectin-like 2 (Necl2) through the IgV domain. However, the role of the IgC domain during this ligand recognition has yet to be understood. In this study, we show the purification of soluble-folded Ig domains of CRTAM, and we demonstrate that the IgC domain forms a homodimer in solution via hydrophobic interactions. By surface plasmon resonance (SPR) analysis, we also demonstrate that CRTAM binds to Necl2 with an affinity of 2.16 nM. In conclusion, CRTAM's IgC is essential for a high-affinity interaction with Necl-2., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest., (© 2024 The Authors. Published by Elsevier B.V.)

Idiopathic inflammatory myopathies are a heterogeneous group of rare autoimmune disorders characterized by progressive muscle weakness and the histopathologic findings of inflammatory infiltrates in muscle tissue. Although their pathogenesis remains indefinite, the association of autoantibodies with clinical manifestations and the evidence of high effectiveness of depleting therapies suggest that B cells could be implicated. Therefore, we explored the landscape of peripheral B cells in this disease by multiparametric flow cytometry, finding significant numerical decreases in memory and double-negative subsets, as well as an expansion of the naive compartment relative to healthy controls, that contribute to defining disease-associated B-cell subset signatures and correlating with different clinical features of patients. Additionally, we determined the potential value of these subsets as diagnostic biomarkers, thus positioning B cells as neglected key elements possibly participating in idiopathic inflammatory myopathy onset or development., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Leukocyte Biology.)

Leukocyte count is routinely performed for diagnostic purposes and is rapidly emerging as a significant biomarker for a wide array of diseases. Additionally, leukocytes have demonstrated considerable promise in novel cell-based immunotherapies. However, the direct retrieval of leukocytes from whole blood is a significant challenge due to their low abundance compared to erythrocytes. Here, we introduce a microfluidic-based platform that isolates and recovers leukocytes from diluted whole blood in a single step. Our platform utilizes a novel, sheathless method to initially sediment and focus blood cells into a dense stream while flowing through a tubing before entering the microfluidic device. A hexagonal-shaped structure, patterned at the device's inlet, directs all the blood cells against the channel's outer walls. The focused cells are then separated based on their size using the deterministic lateral displacement (DLD) microfluidic technique. We evaluated various parameters that could influence leukocyte separation, including different focusing structures (assessed both computationally and experimentally), the orientation of the tubing-chip interface, the effects of blood sample hematocrit (dilution), and flow rate. Our device demonstrated the ability to isolate leukocytes from diluted blood with a separation efficiency of 100%, a recovery rate of 76%, and a purity of 80%, while maintaining a cell viability of 98%. The device operates for over 30 min at a flow rate of 2 μL min -1 . Furthermore, we developed a handheld pressure controller to drive fluid flow, enhancing the operability of our platform outside of central laboratories and enabling near-patient testing. Our platform can be integrated with downstream cell-based assays and analytical methods that require high leukocyte purity (80%), ranging from cell counting to diagnostics and cell culture applications.

Immune dysregulation and cancer treatment may affect SARS-CoV-2 vaccination protection. Antibody production by B-cells play a vital role in the control and clearance of the SARS-CoV-2 virus. This study prospectively explores B-cell seroconversion following SARS-CoV-2 immunization in healthy individuals and non-small cell lung cancer (NSCLC) patients undergoing oncological treatment. 92 NSCLC patients and 27 healthy individuals' blood samples were collected after receiving any COVID-19 vaccine. Serum and mononuclear cells were isolated, and a serum surrogate virus neutralization test kit evaluated SARS-CoV-2 antibodies. B-cell subpopulations on mononuclear cells were characterized by flow cytometry. Patients were compared based on vaccination specifications and target mutation oncological treatment. A higher percentage of healthy individuals developed more SARS-CoV-2 neutralizing antibodies than NSCLC patients (63% vs. 54.3%; p = 0.03). NSCLC patients receiving chemotherapy (CTX) or tyrosine kinase inhibitors (TKIs) developed antibodies in 45.2% and 53.7%, of cases, respectively, showing an impaired antibody generation. CTX patients exhibited trends towards lower median antibody production than TKIs (1.0, IQR 83 vs. 38.23, IQR 89.22; p = 0.069). Patients receiving immunotherapy did not generate antibodies. A sub-analysis revealed that those with ALK mutations exhibited non-significant trends towards higher antibody titers (63.02, IQR 76.58 vs. 21.78, IQR 93.5; p = 0.1742) and B-cells quantification (10.80, IQR 7.52 vs. 7.22, IQR 3.32; p = 0.1382) against the SARS-CoV-2 spike protein than EGFR patients; nonetheless, these differences were not statistically significant. This study shows that antibodies against SARS-CoV-2 may be impaired in patients with NSCLC secondary to EGFR-targeted TKIs compared to ALK-directed treatment.

Cellular communication depends heavily on the participation of vesicular systems generated by most cells of an organism. Exosomes play central roles in this process. Today, these vesicles have been characterized, and it has been determined that the cargo they transport is not within a random system. In fact, it depends on various molecular signals and the recruitment of proteins that participate in the biogenesis of exosomes. It has also been shown that multiple viruses can recruit these vesicles to transport viral factors such as genomes or proteins. It has been shown that the late domains present in viral proteins are critical for the exosomal selection and biogenesis systems to recognize these viral proteins and introduce them into the exosomes. In this review, the researchers discuss the evidence related to the characterization of these late domains and their role in exosome recruitment during viral infection.

Background: Currently, there is scant information regarding the features associated to the persistence of post-COVID-19 syndrome, which is the main aim of the present study., Methods: A cohort study of 102 COVID-19 patients was conducted. The post-COVID-19 symptoms were assessed by a standardised questionnaire. Lymphocyte immunophenotyping was performed by flow cytometry and chemokines/cytokines, neutrophil extracellular traps, the tripartite motif 63, anti-cellular, and anti-SARS-CoV-2 IgG antibodies were addressed in serum. The primary outcome was the persistence of post-COVID-19 syndrome after six months follow-up., Results: Thirteen patients (12.7%) developed the primary outcome and had a more frequent history of post-COVID-19 syndrome 3 months after infection onset ( p  = .044), increased levels of IL-1α ( p  = .011) and IP-10 ( p  = .037) and increased CD57 expression in CD8 + T cells ( p  = .003). There was a trend towards higher levels of IFN-γ ( p  = .051), IL-1β ( p  = .062) and IL-6 ( p  = .087). The history of post COVID-19 in the previous 3 months, obesity, baseline serum MIP-1α and IP-10, and CD57 expression in CD8 + T cells were independently associated with the persistence of post-COVID-19 syndrome., Conclusion: Our data suggest an important relationship between a pro-inflammatory state mediated through metabolic pathways related to obesity and increased cellular senescence as a key element in the persistence of post-COVID-19 syndrome at six months of follow-up.

B lymphocytes are a leukocyte subset capable of developing several functions apart from differentiating into antibody-secreting cells. These processes are triggered by external activation signals that induce changes in the plasma membrane properties, regulated by the formation of different lipid-bilayer subdomains that are associated with the underlying cytoskeleton through different linker molecules, thus allowing the functional specialization of regions within the membrane. Among these, there are tetraspanin-enriched domains. Tetraspanins constitute a superfamily of transmembrane proteins that establish lateral associations with other molecules, determining its activity and localization. In this study, we identified TSPAN33 as an active player during B-lymphocyte cytoskeleton and plasma membrane-related phenomena, including protrusion formation, adhesion, phagocytosis, and cell motility. By using an overexpression model of TSPAN33 in human Raji cells, we detected a specific distribution of this protein that includes membrane microvilli, the Golgi apparatus, and extracellular vesicles. Additionally, we identified diminished phagocytic ability and altered cell adhesion properties due to the aberrant expression of integrins. Accordingly, these cells presented an enhanced migratory phenotype, as shown by its augmented chemotaxis and invasion rates. When we evaluated the mechanic response of cells during fibronectin-induced spreading, we found that TSPAN33 expression inhibited changes in roughness and membrane tension. Contrariwise, TSPAN33 knockdown cells displayed opposite phenotypes to those observed in the overexpression model. Altogether, our data indicate that TSPAN33 represents a regulatory element of the adhesion and migration of B lymphocytes, suggesting a novel implication of this tetraspanin in the control of the mechanical properties of their plasma membrane., (© 2020 Federation of European Biochemical Societies.)

The profiling of the effector functions of single immune cells─including cytokine secretion─can lead to a deeper understanding of how the immune system operates and to potential diagnostics and therapeutical applications. Here, we report a microfluidic device that pairs single cells and antibody-functionalized microbeads in hydrodynamic traps to quantitate cytokine secretion. The device contains 1008 microchambers, each with a volume of ∼500 pL, divided into six different sections individually addressed to deliver an equal number of chemical stimuli. Integrating microvalves allowed us to isolate cell/bead pairs, preventing cross-contamination with factors secreted by adjacent cells. We implemented a fluorescence sandwich immunoassay on the biosensing microbeads with a limit of detection of 9 pg/mL and were able to detect interleukin-8 (IL-8) secreted by single blood-derived human monocytes in response to different concentrations of LPS. Finally, our platform allowed us to observe a significant decrease in the number of IL-8-secreting monocytes when paracrine signaling becomes disrupted. Overall, our platform could have a variety of applications for which the analysis of cellular function heterogeneity is necessary, such as cancer research, antibody discovery, or rare cell screening.

Introduction: Immunoglobulin A (IgA) is the main antibody isotype in body fluids such as tears, intestinal mucous, colostrum, and saliva. There are two subtypes of IgA in humans: IgA1, mainly present in blood and mucosal sites, and IgA2, preferentially expressed in mucosal sites like the colon. In clinical practice, immunoglobulins are typically measured in venous or capillary blood; however, alternative samples, including saliva, are now being considered, given their non-invasive and easy collection nature. Several autoimmune diseases have been related to diverse abnormalities in oral mucosal immunity, such as rheumatoid arthritis, Sjogren's syndrome, and systemic lupus erythematosus (SLE)., Methods: We decided to evaluate the levels of both IgA subtypes in the saliva of SLE patients. A light chain capture-based ELISA measured specific IgA1 and IgA2 levels in a cohort of SLE patients compared with age and gender-matched healthy volunteers., Results: Surprisingly, our results indicated that in the saliva of SLE patients, total IgA and IgA1 subtype were significantly elevated; we also found that salivary IgA levels, particularly IgA2, positively correlate with anti-dsDNA IgG antibody titers. Strikingly, we also detected the presence of salivary anti-nucleosome IgA antibodies in SLE patients, a feature not previously reported elsewhere., Conclusions: According to our results and upon necessary validation, IgA characterization in saliva could represent a potentially helpful tool in the clinical care of SLE patients with the advantage of being a more straightforward, faster, and safer method than manipulating blood samples., 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 © 2023 Romero-Ramírez, Sosa-Hernández, Cervantes-Díaz, Carrillo-Vázquez, Meza-Sánchez, Núñez-Álvarez, Torres-Ruiz, Gómez-Martín and Maravillas-Montero.)

Objective: To assess the proportion of myeloid-derived suppressor cells (MDSCs), their expression of arginase-1 and programmed cell death ligand 1 (PD-L1) and their relationship with the clinical phenotype of patients with idiopathic inflammatory myopathies (IIMs)., Methods: We recruited 37 IIM adult patients and 10 healthy donors in Mexico City. We evaluated their clinical features, the proportion of MDSCs and their expression of PD-L1 and arginase-1 by flow cytometry. Polymorphonuclear (PMN)-MDSCs were defined as CD33dim, CD11b+ and CD66b+ while monocytic (M)-MDSCs were CD33+, CD11b+, HLA-DR- and CD14+. Serum cytokines were analysed with a multiplex assay. We compared the quantitative variables with the Kruskal-Wallis and Mann-Whitney U tests and assessed correlations with Spearman's ρ., Results: Most patients had dermatomyositis [n = 30 (81.0%)]. IIM patients had a peripheral expansion of PMN-MDSCs and M-MDSCs with an enhanced expression of arginase-1 and PD-L1. Patients with active disease had a decreased percentage {median 1.75% [interquartile range (IQR) 0.31-5.50 vs 10.71 [3.16-15.58], P = 0.011} of M-MDSCs and a higher absolute number of PD-L1+ M-MDSCs [median 23.21 cells/mm3 (IQR 11.16-148.9) vs 5.95 (4.66-102.7), P = 0.046] with increased expression of PD-L1 [median 3136 arbitrary units (IQR 2258-4992) vs 1961 (1885-2335), P = 0.038]. PD-L1 expression in PMN-MDSCs correlated with the visual analogue scale of pulmonary disease activity (r = 0.34, P = 0.040) and damage (r = 0.36, P = 0.031), serum IL-5 (r = 0.55, P = 0.003), IL-6 (r = 0.46, P = 0.003), IL-8 (r = 0.53, P = 0.018), IL-10 (r = 0.48, P = 0.005) and GM-CSF (r = 0.48, P = 0.012). M-MDSCs negatively correlated with the skeletal Myositis Intention to Treat Index (r = -0.34, P = 0.038) and positively with IL-6 (r = 0.40, P = 0.045)., Conclusion: MDSCs expressing arginase-1 and PD-L1 are expanded in IIM and correlate with disease activity, damage accrual and serum cytokines., (© The Author(s) 2022. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Tuberculosis (TB) of the central nervous system (CNS) presents high mortality due to brain damage and inflammation events. The formation and deposition of immune complexes (ICs) in the brain microvasculature during Mycobacterium tuberculosis (Mtb) infection are crucial for its pathobiology. The relevance of ICs to Mtb antigens in the pathogenesis of CNS-TB has been poorly explored. Here, we aimed to establish a murine experimental model of ICs-mediated brain vasculitis induced by cell wall antigens of Mtb. We administered a cell wall extract of the prototype pathogenic Mtb strain H37Rv to male BALB/c mice by subcutaneous and intravenous routes. Serum concentration and deposition of ICs onto blood vessels were determined by polyethylene glycol precipitation, ELISA, and immunofluorescence. Histopathological changes in the brain, lung, spleen, liver, and kidney were evaluated by hematoxylin and eosin staining. Our results evidenced that vasculitis developed in the studied tissues. High serum levels of ICs and vascular deposition were evident in the brain, lung, and kidneys early after the last cell wall antigen administration. Cell wall Mtb antigens induce strong type III hypersensitivity reactions and the development of systemic vasculitis with brain vascular changes and meningitis, supporting a role for ICs in the pathogenesis of TB.

It is well known that the presence of comorbidities and age-related health issues may hide biochemical and metabolic features triggered by SARS-CoV-2 infection and other diseases associated to hypoxia, as they are by themselves chronic inflammatory conditions that may potentially disturb metabolic homeostasis and thereby negatively impact on COVID-19 progression. To unveil the metabolic abnormalities inherent to hypoxemia caused by COVID-19, we here applied gas chromatography coupled to mass spectrometry to analyze the main metabolic changes exhibited by a population of male patients less than 50 years of age with mild/moderate and severe COVID-19 without pre-existing comorbidities known to predispose to life-threatening complications from this infection. Several differences in serum levels of particular metabolites between normal controls and patients with COVID-19 as well as between mild/moderate and severe COVID-19 were identified. These included increased glutamic acid and reduced glutamine, cystine, threonic acid, and proline levels. In particular, using the entire metabolomic fingerprint obtained, we observed that glutamine/glutamate metabolism was associated with disease severity as patients in the severe COVID-19 group presented the lowest and higher serum levels of these amino acids, respectively. These data highlight the hypoxia-derived metabolic alterations provoked by SARS-CoV-2 infection in the absence of pre-existing co-morbidities as well as the value of amino acid metabolism in determining reactive oxygen species recycling pathways, which when impaired may lead to increased oxidation of proteins and cell damage. They also provide insights on new supportive therapies for COVID-19 and other disorders that involve altered redox homeostasis and lower oxygen levels that may lead to better outcomes of disease severity., Competing Interests: The authors have declared that no competing interests exist.

Background: Until now, most of the research addressing long-term humoral responses in coronavirus disease 2019 (COVID-19) had only evaluated the serum titers of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgGs, without the assessment of the baseline antiviral clinical and immune profile, which is the aim of this study and may be the key factor leading to a broad and sustained antibody response., Methods: We included 103 patients with COVID-19. When the patients sought medical attention (baseline), a blood sample was drawn to perform immunophenotype of lymphocytes by flow cytometry. The patients were assessed 15 days after baseline and then every month until the third month, followed by a last visit 6 months after recruitment. We evaluated the anti-SARS-COV-2 IgG at all time points, and the serum levels of cytokines, chemokines, anti-cellular (AC) antibodies and neutrophil extracellular traps were also assessed during the follow-up. The primary outcome of the study was the presence of a sustained immune humoral response, defined as an anti-SARS-CoV-2 IgG titer >4.99 arbitrary units/mL in at least two consecutive measures. We used generalized lineal models to assess the features associated with this outcome and to assess the effect of the changes in the cytokines and chemokines throughout time on the development of a sustained humoral immune response., Results: At baseline the features associated to a sustained immune humoral response were the diagnosis of critical disease, absolute number of lymphocytes, serum IP-10, IL-4, IL-2, regulatory T cells, CD8 + T cells, and positive AC antibodies. Critical illness and the positivity of AC antibodies were associated with a sustained humoral immune response after 3 months, whilst critical illness and serum IL-13 were the explanatory variables after 6 months., Conclusion: A sustained immune humoral response is strongly related to critical COVID-19, which is characterized by the presence of AC antibodies, quantitative abnormalities in the T cell compartment, and the serum cytokines and chemokines during acute infection and throughout time., 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 © 2022 Torres-Ruiz, Lomelín-Gascón, Vargas-Castro, Lira-Luna, Pérez-Fragoso, Tapia-Conyer, Nuñez-Aguirre, Alcalá-Carmona, Absalón-Aguilar, Maravillas-Montero, Mejía-Domínguez, Núñez-Álvarez, Rull-Gabayet, Llorente, Romero-Ramírez, Sosa-Hernández, Cervantes-Díaz, Juárez-Vega, Meza-Sánchez, Martínez-Juárez, Morales-Juárez, López-López, Negrete-Trujillo, Falcón-Lezama, Valdez-Vázquez, Gallardo-Rincón and Gómez-Martín.)

The contribution of B cells in COVID-19 pathogenesis, beyond the production of specific antibodies against SARS-CoV-2, is still not well understood. Since one of their most relevant functional roles includes their immune-suppressive mechanisms, we decided to evaluate one of the most recognized human B regulatory subpopulations: the IL-10 + B10 cells, during COVID-19 onset. After stimulation of PBMCs for IL-10 induction, we employed multiparametric flow cytometry to determine B10 frequencies in severe and critical COVID-19 patients and then correlated those with clinical and laboratory parameters. Compared with healthy individuals, we detected a significant reduction in the B10 subset in both patient groups, which correlates with some inflammatory parameters that define the disease severity. This evidence suggests an aberrant role of B10 cells in immune responses against SARS-CoV-2 that needs to be further explained., (©2022 Society for Leukocyte Biology.)

Lupus nephritis (LN) is one of the most common manifestations of systemic lupus erythematosus (SLE), characterized by abnormal B cell activation and differentiation to memory or plasma effector cells. However, the role of these cells in the pathogenesis of LN is not fully understood, as well as the effect of induction therapy on B cell subsets, possibly associated with this manifestation, like aged-associated B cells (ABCs). Consequently, we analyzed the molecules defining the ABCs subpopulation (CD11c, T-bet, and CD21) through flow cytometry of blood samples from patients with lupus presenting or not LN, following up a small sub-cohort after six months of induction therapy. The frequency of ABCs resulted higher in LN patients compared to healthy subjects. Unexpectedly, we identified a robust reduction of a CD21 hi subset that was almost specific to LN patients. Moreover, several clinical and laboratory lupus features showed strong and significant correlations with this undefined B cell subpopulation. Finally, it was observed that the induction therapy affected not only the frequencies of ABCs and CD21 hi subsets but also the phenotype of the CD21 hi subset that expressed a higher density of CXCR5. Collectively, our results suggest that ABCs, and more importantly the CD21 hi subset, may work to assess therapeutic response since the reduced frequency of CD21 hi cells could be associated with the onset of LN., 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 © 2022 Sosa-Hernández, Romero-Ramírez, Cervantes-Díaz, Carrillo-Vázquez, Navarro-Hernandez, Whittall-García, Absalón-Aguilar, Vargas-Castro, Reyes-Huerta, Juárez-Vega, Meza-Sánchez, Ortiz-Navarrete, Torres-Ruiz, Mejía-Domínguez, Gómez-Martín and Maravillas-Montero.)

The process by which blood cells are generated has been widely studied in homeostasis and during pathogen-triggered inflammatory response. Recently, murine lungs have been shown to be a significant source of hematopoietic progenitors in a process known as extramedullary hematopoiesis. Using multiparametric flow cytometry, we have identified mesenchymal, endothelial, and hematopoietic progenitor cells that express the secreted small protein Isthmin 1 (ISM1). Further characterization of hematopoietic progenitor cells indicated that ISM1 + Lineage - Sca-1 + c-kit + (ISM1 + LSK) cells are enriched in short-term hematopoietic stem cells (ST-HSCs). Moreover, most Sca-1 + ISM1 + cells express the residence marker CD49a, and this correlated with their localization in the extravascular region of the lung, indicating that ISM1 + cells are lung-resident cells. We also observed that ISM1 + cells express TLR4, TLR5, and TLR9, and, in a mouse model of sepsis induced by P. aeruginosa , we observed that all the LSK and ISM1 + LSK cells were affected. We conclude that ISM1 is a novel biomarker associated with progenitor-like cells. ISM1 + cells are involved in the response to a bacterial challenge, suggesting an association between ISM1-producing cells and dangerous inflammatory responses like sepsis., Competing Interests: The authors declare no conflict of interest., (Copyright © 2022 Guadalupe Rivera-Torruco et al.)

Background/objective: Biomarkers for disease activity and damage accrual in idiopathic inflammatory myopathies (IIMs) are currently lacking. The purpose of this cross-sectional study is to analyze the relationship among low-density granulocytes (LDGs), neutrophil extracellular traps (NETs), and clinical and immunological features of patients with IIM., Methods: We assessed disease activity, damage accrual, amount of LDGs, NETs, expression of LL-37, and serum cytokines in 65 adult patients with IIM. Differences between groups and correlations were assessed by Kruskal-Wallis, Mann-Whitney U, and Spearman ρ tests. The association between LDGs, NETs, disease activity, calcinosis, and cutaneous ulcers was assessed by logistic regression. To address the capacity of LDGs and NETs to diagnose disease activity, we used receiving operating characteristic curves., Results: Low-density granulocytes were higher in patients with active disease, ulcers, calcinosis, and anti-MDA5 antibodies, which correlated with serum levels of IL-17A and IL-18. Neutrophil extracellular traps were higher in patients with calcinosis, elevated titers of antinuclear antibodies, and positive anti-PM/Scl75 tests. The combination of a high proportion of both total LDGs and NETs was associated with the presence of calcinosis and cutaneous ulcers. LL-37 was higher in NETs originating from LDGs. Normal-density neutrophils were elevated in patients with active dermatomyositis., Conclusions: Low-density granulocytes and NETs containing LL-37 are increased in patients with IIM and active disease, and correlate with proinflammatory cytokines. Both total and CD10+ LDGs are potential biomarkers for disease activity and, in combination with NETs, have the potential to detect patients who are at risk for cutaneous ulcers and calcinosis., Competing Interests: The authors declare no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: The role of B cells in COVID-19, beyond the production of specific antibodies against SARS-CoV-2, is still not well understood. Here, we describe the novel landscape of circulating double-negative (DN) CD27 - IgD - B cells in COVID-19 patients, representing a group of atypical and neglected subpopulations of this cell lineage., Methods: Using multiparametric flow cytometry, we determined DN B cell subset amounts from 91 COVID-19 patients, correlated those with cytokines, clinical and laboratory parameters, and segregated them by principal components analysis., Results: We detected significant increments in the DN2 and DN3 B cell subsets, while we found a relevant decrease in the DN1 B cell subpopulation, according to disease severity and patient outcomes. These DN cell numbers also appeared to correlate with pro- or anti-inflammatory signatures, respectively, and contributed to the segregation of the patients into disease severity groups., Conclusion: This study provides insights into DN B cell subsets' potential role in immune responses against SARS-CoV-2, particularly linked to the severity of COVID-19., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

NK cells play an important role in immunity by recognizing and eliminating cells undergoing infection or malignant transformation. This role is dependent on the ability of NK cells to lyse targets cells in a perforin-dependent mechanism and by secreting inflammatory cytokines. Both effector functions are controlled by several cell surface receptors. The Signaling Lymphocyte Activation Molecule (SLAM) family of receptors plays an essential role in regulating NK cell activation. Several studies have demonstrated that SLAMF7 regulates NK cell activation. However, the molecular and cellular mechanisms by which SLAMF7 influences NK effector functions are unknown. Here, we present evidence that physiological ligation of SLAMF7 in human NK cells enhances the lysis of target cells expressing SLAMF7. This effect was dependent on the ability of SLAMF7 to promote NK cell degranulation rather than cytotoxic granule polarization or cell adhesion. Moreover, SLAMF7-dependent NK cell degranulation was predominantly dependent on PLC-γ when compared to PI3K. These data provide novel information on the cellular mechanism by which SLAMF7 regulates human NK cell activation. Finally, this study supports a model for NK cell activation where activated receptors contribute by regulating specific discrete cellular events rather than multiple cellular processes., (© 2021 Wiley-VCH GmbH.)

Abstract: Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease with a wide range of clinical presentations. Lupus nephritis (LN) is a frequent complication of SLE, representing a significant cause of morbidity and mortality in these patients. In addition, LN diagnosis remains suboptimal in most clinical contexts. The current gold standard for LN clinical diagnosis is a renal biopsy. Still, the invasiveness of this technique is an obstacle to the early detection of renal involvement and further monitoring of treatment results. Consequently, there are different areas for improvement in the field of LN, such as the search for novel non-invasive clinical biomarkers with an adequate correlation between clinical manifestations and actual histological damage. Although urine component-related studies are promising, the more robust blood/serum biomarkers may still be helpful in developing point-of-care systems that can be adapted to most clinical scenarios. Therefore, this brief review aims to highlight and summarize some of the most recently reported non-classical serum/blood potential LN biomarkers. (Rev Invest Clin. 2022;74(5):227-31)., (Copyright: © 2022 Permanyer.)

The coronavirus disease 2019 (COVID-19) pandemic has reached an unprecedented level. There is a strong demand for diagnostic and serological supplies worldwide, making it necessary for countries to establish their own technologies to produce high-quality biomolecules. The two main viral antigens used for the diagnostics for severe acute respiratory syndrome coronavirus (SARS-CoV-2) are the structural proteins spike (S) protein and nucleocapsid (N) protein. The spike protein of SARS-CoV-2 is cleaved into S1 and S2, in which the S1 subunit has the receptor-binding domain (RBD), which induces the production of neutralizing antibodies, whereas nucleocapsid is an ideal target for viral antigen-based detection. In this study, we designed plasmids, pcDNA3.1/S1 and pcDNA3.1/N, and optimized their expression of the recombinant S1 and N proteins from SARS-CoV-2 in a mammalian system. The RBD was used as a control. The antigens were successfully purified from Expi293 cells, with high yields of the S1, N, and RBD proteins. The immunogenic abilities of these proteins were demonstrated in a mouse model. Further, enzyme-linked immunosorbent assays with human serum samples showed that the SARS-CoV-2 antigens are a suitable alternative for serological assays to identify patients infected with COVID-19.

The coronavirus disease 2019 (COVID-19) is related to enhanced production of NETs, and autoimmune/autoinflammatory phenomena. We evaluated the proportion of low-density granulocytes (LDG) by flow cytometry, and their capacity to produce NETs was compared with that of conventional neutrophils. NETs and their protein cargo were quantified by confocal microscopy and ELISA. Antinuclear antibodies (ANA), anti-neutrophil cytoplasmic antibodies (ANCA) and the degradation capacity of NETs were addressed in serum. MILLIPLEX assay was used to assess the cytokine levels in macrophages' supernatant and serum. We found a higher proportion of LDG in severe and critical COVID-19 which correlated with severity and inflammatory markers. Severe/critical COVID-19 patients had higher plasmatic NE, LL-37 and HMGB1-DNA complexes, whilst ISG-15-DNA complexes were lower in severe patients. Sera from severe/critical COVID-19 patients had lower degradation capacity of NETs, which was reverted after adding hrDNase. Anti-NET antibodies were found in COVID-19, which correlated with ANA and ANCA positivity. NET stimuli enhanced the secretion of cytokines in macrophages. This study unveils the role of COVID-19 NETs as inducers of pro-inflammatory and autoimmune responses. The deficient degradation capacity of NETs may contribute to the accumulation of these structures and anti-NET antibodies are related to the presence of autoantibodies.

Background: Most of the explanatory and prognostic models of COVID-19 lack of a comprehensive assessment of the wide COVID-19 spectrum of abnormalities. The aim of this study was to unveil novel biological features to explain COVID-19 severity and prognosis (death and disease progression)., Methods: A predictive model for COVID-19 severity in 121 patients was constructed by ordinal logistic regression calculating odds ratio (OR) with 95% confidence intervals (95% CI) for a set of clinical, immunological, metabolomic, and other biological traits. The accuracy and calibration of the model was tested with the area under the curve (AUC), Somer's D, and calibration plot. Hazard ratios with 95% CI for adverse outcomes were calculated with a Cox proportional-hazards model., Results: The explanatory variables for COVID-19 severity were the body mass index (BMI), hemoglobin, albumin, 3-Hydroxyisovaleric acid, CD8+ effector memory T cells, Th1 cells, low-density granulocytes, monocyte chemoattractant protein-1, plasma TRIM63, and circulating neutrophil extracellular traps. The model showed an outstanding performance with an optimism-adjusted AUC of 0.999, and Somer's D of 0.999. The predictive variables for adverse outcomes in COVID-19 were severe and critical disease diagnosis, BMI, lactate dehydrogenase, Troponin I, neutrophil/lymphocyte ratio, serum levels of IP-10, malic acid, 3, 4 di-hydroxybutanoic acid, citric acid, myoinositol, and cystine., Conclusions: Herein, we unveil novel immunological and metabolomic features associated with COVID-19 severity and prognosis. Our models encompass the interplay among innate and adaptive immunity, inflammation-induced muscle atrophy and hypoxia as the main drivers of COVID-19 severity., 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 Torres-Ruiz, Pérez-Fragoso, Maravillas-Montero, Llorente, Mejía-Domínguez, Páez-Franco, Romero-Ramírez, Sosa-Hernández, Cervantes-Díaz, Absalón-Aguilar, Nuñez-Aguirre, Juárez-Vega, Meza-Sánchez, Kleinberg-Bid, Hernández-Gilsoul, Ponce-de-León and Gómez-Martín.)

The immune response plays a critical role in the pathophysiology of SARS-CoV-2 infection ranging from protection to tissue damage and all occur in the development of acute respiratory distress syndrome (ARDS). ARDS patients display elevated levels of inflammatory cytokines and innate immune cells, and T and B cell lymphocytes have been implicated in this dysregulated immune response. Mast cells are abundant resident cells of the respiratory tract and are able to release different inflammatory mediators rapidly following stimulation. Recently, mast cells have been associated with tissue damage during viral infections, but their role in SARS-CoV-2 infection remains unclear. In this study, we examined the profile of mast cell activation markers in the serum of COVID-19 patients. We noticed that SARS-CoV-2-infected patients showed increased carboxypeptidase A3 (CPA3) and decreased serotonin levels in their serum when compared with symptomatic SARS-CoV-2-negative patients. CPA3 levels correlated with C-reactive protein, the number of circulating neutrophils, and quick SOFA. CPA3 in serum was a good biomarker for identifying severe COVID-19 patients, whereas serotonin was a good predictor of SARS-CoV-2 infection. In summary, our results show that serum CPA3 and serotonin levels are relevant biomarkers during SARS-CoV-2 infection. This suggests that mast cells and basophils are relevant players in the inflammatory response in COVID-19 and may represent targets for therapeutic intervention., (©2021 Society for Leukocyte Biology.)

Pancreatic cancer remains one of the most lethal diseases with dismal five-year survival rates. Although mutant KRas protein-driven activation of downstream MAPK Raf/MEK/ERK and PI3K/Akt signaling pathways represent major oncogenic alterations, signaling blockade with MEK and PI3K inhibitors has shown that intrinsic resistance may hamper the effectiveness of this targeted approach. However, there have been no mass spectrometry-based proteomic studies for in-depth comparison of protein expression differences between pancreatic cancer cells with sensitivity and resistance to MEK and PI3K kinase inhibitors. In this work, we compared PANC-1 and MIA PaCa-2 pancreatic cancer cells which are, respectively, resistant and sensitive to MEK- and PI3K-targeted therapy. We conducted a label-free data-independent acquisition mass spectrometry (SWATH-MS) study with extensive peptide fractionation to quantitate 4808 proteins and analyze differential expression of 743 proteins between resistant and sensitive cells. This allowed identification of the tumor suppressor protein phosphatase 2A (PP2A) and proteins from mitochondrial respiratory complex I implicated in oxidative phosphorylation as alternative candidate drug targets for cells resistant to MEK and PI3K inhibition. PP2A activator DT-061 decreased viability of PANC-1 cells and this was accompanied by reduced expression of c-Myc. PANC-1 cells also showed response to metformin and the novel complex I inhibitor IACS-010759. These findings provide insights into the distinct cellular proteomes and point out alternative pharmacological targets for MEK and PI3K inhibition-resistant pancreatic cancer cells., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Extracellular vesicles, EVs, are a heterogeneous complex of lipidic membranes, secreted by any cell type, in any fluid such as urine. EVs can be of different sizes ranging from 40-100 nm in diameter such as in exosomes to 100-1000 nm in microvesicles. They can also contain different molecules that can be used as biomarkers for the prognosis and diagnosis of many diseases. Many techniques have been developed to characterize these vesicles. One of these is flow cytometry. However, there are no existing reports to show how to quantify the concentration of EVs and differentiate them by size, along with biomarker detection. This work aims to describe a procedure for the isolation, quantification, and phenotypification of urinary extracellular vesicles, uEVs, using a conventional cytometer for the analysis without any modification to its configuration. The method's limitations include staining a maximum of four different biomarkers per sample. The method is also limited by the amount of EVs available in the sample. Despite these limitations, with this protocol and its subsequent analysis, we can obtain more information on the enrichment of EVs markers and the abundance of these vesicles present in urine samples, in diseases involving kidney and brain damage.

We identified the main changes in serum metabolites associated with severe (n = 46) and mild (n = 19) COVID-19 patients by gas chromatography coupled to mass spectrometry. The modified metabolic profiles were associated to an altered amino acid catabolism in hypoxic conditions. Noteworthy, three α-hydroxyl acids of amino acid origin increased with disease severity and correlated with altered oxygen saturation levels and clinical markers of lung damage. We hypothesize that the enzymatic conversion of α-keto-acids to α- hydroxyl-acids helps to maintain NAD recycling in patients with altered oxygen levels, highlighting the potential relevance of amino acid supplementation during SARS-CoV-2 infection.

Context: Follicle-stimulating hormone (FSH) plays an essential role in gonadal function. Loss-of-function mutations in the follicle-stimulating hormone receptor (FSHR) are an infrequent cause of primary ovarian failure., Objective: To analyze the molecular physiopathogenesis of a novel mutation in the FSHR identified in a woman with primary ovarian failure, employing in vitro and in silico approaches, and to compare the features of this dysfunctional receptor with those shown by the trafficking-defective D408Y FSHR mutant., Methods: Sanger sequencing of the FSHR cDNA was applied to identify the novel mutation. FSH-stimulated cyclic adenosine monophosphate (cAMP) production, ERK1/2 phosphorylation, and desensitization were tested in HEK293 cells. Receptor expression was analyzed by immunoblotting, receptor-binding assays, and flow cytometry. Molecular dynamics simulations were performed to determine the in silico behavior of the mutant FSHRs., Results: A novel missense mutation (I423T) in the second transmembrane domain of the FSHR was identified in a woman with normal pubertal development but primary amenorrhea. The I423T mutation slightly impaired plasma membrane expression of the mature form of the receptor and severely impacted on cAMP/protein kinase A signaling but much less on β-arrestin-dependent ERK1/2 phosphorylation. Meanwhile, the D408Y mutation severely affected membrane expression, with most of the FSH receptor located intracellularly, and both signal readouts tested. Molecular dynamics simulations revealed important functional disruptions in both mutant FSHRs, mainly the loss of interhelical connectivity in the D408Y FSHR., Conclusions: Concurrently, these data indicate that conformational differences during the inactive and active states account for the distinct expression levels, differential signaling, and phenotypic expression of the I423T and D408Y mutant FSHRs., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: SARS-CoV-2 infection represents a global health problem that has affected millions of people. The fine host immune response and its association with the disease course have not yet been fully elucidated. Consequently, we analyze circulating B cell subsets and their possible relationship with COVID-19 features and severity., Methods: Using a multiparametric flow cytometric approach, we determined B cell subsets frequencies from 52 COVID-19 patients, grouped them by hierarchical cluster analysis, and correlated their values with clinical data., Results: The frequency of CD19 + B cells is increased in severe COVID-19 compared to mild cases. Specific subset frequencies such as transitional B cell subsets increase in mild/moderate cases but decrease with the severity of the disease. Memory B compartment decreased in severe and critical cases, and antibody-secreting cells are increased according to the severity of the disease. Other non-typical subsets such as double-negative B cells also showed significant changes according to disease severity. Globally, these differences allow us to identify severity-associated patient clusters with specific altered subsets. Finally, respiratory parameters, biomarkers of inflammation, and clinical scores exhibited correlations with some of these subpopulations., Conclusions: The severity of COVID-19 is accompanied by changes in the B cell subpopulations, either immature or terminally differentiated. Furthermore, the existing relationship of B cell subset frequencies with clinical and laboratory parameters suggest that these lymphocytes could serve as potential biomarkers and even active participants in the adaptive antiviral response mounted against SARS-CoV-2., 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 © 2020 Sosa-Hernández, Torres-Ruíz, Cervantes-Díaz, Romero-Ramírez, Páez-Franco, Meza-Sánchez, Juárez-Vega, Pérez-Fragoso, Ortiz-Navarrete, Ponce-de-León, Llorente, Berrón-Ruiz, Mejía-Domínguez, Gómez-Martín and Maravillas-Montero.)

Background: Neutrophil extracellular traps (NETs) from patients with systemic lupus erythematosus (SLE) are characterized by lower ubiquitylation and myeloperoxidase (MPO) as a substrate. The structural and functional effect of such modification and if there are additional post-translational modifications (PTMs) are unknown., Methods: To assess the expression and functional role of PTMs in NETs of patients with SLE; reactivation, proliferation and cytokine production was evaluated by flow cytometry using co-cultures with dendritic cells (DC) and CD4 + from SLE patients and healthy controls. The impact of ubiquitylation on MPO was assessed by molecular dynamics. The expression of ISG15 in NETs was evaluated by immunofluorescence and Western Blot., Results: Fifteen patients with SLE and ten healthy controls were included. In the co-cultures of CD4 + lymphocytes with DC stimulated with ubiquitylated MPO or recombinant MPO, a higher expression of IFNγ and IL-17A was found in CD4 + from SLE patients (p < 0.05). Furthermore, with DC stimulated with ubiquitylated MPO a trend towards increased expression of CD25 and Ki67 was found in lupus CD4 + lymphocytes, while the opposite was documented in controls (p < 0.05). Through molecular dynamics we found the K129-K488-K505 residues of MPO as susceptible to ubiquitylation. Ubiquitylation affects the hydration status of the HEME group depending on the residue to which it is conjugated. R239 was found near by the HEME group when the ubiquitin was in K488-K505. In addition, we found greater expression of ISG15 in the SLE NETs vs controls (p < 0.05), colocalization with H2B (r = 0.81) only in SLE samples and increased production of IFNγ in PBMCs stimulated with lupus NETs compared to healthy controls NETs., Conclusion: The ubiquitylated MPO has a differential effect on the induction of reactivation of CD4 + lymphocytes in patients with SLE, which may be related to structural changes by ubiquitylation at the catalytic site of MPO. Besides a lower ubiquitylation pattern, NETs of patients with SLE are characterized by the expression of ISG15, and the induction of IFNγ by Th1 cells.

Despite numerous demonstrations that the immune system is activated in heart failure, negatively affecting patients' outcomes, no definitive treatment strategy exists directed to modulate the immune system. In this review, we present the evidence that B cells contribute to the development of hypertrophy, inflammation, and maladaptive tissue remodelling. B cells produce antibodies that interfere with cardiomyocyte function, which culminates as the result of recruitment and activation of a variety of innate and structural cell populations, including neutrophils, macrophages, fibroblasts, and T cells. As B cells appear as active players in heart failure, we propose here novel immunomodulatory therapeutic strategies that target B cells and their products., (© 2020 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.)

Interleukin- (IL-) 17 is increased in acute myocardial infarction (AMI) and plays a key role in inflammatory diseases through its involvement in the activation of leukocytes. Here, we describe for the first time the effect of IL-17 in the migration and activation of monocyte subsets in patients during ST-segment elevation myocardial infarction (STEMI) and post-STEMI. We analyzed the circulating levels of IL-17 in patient plasma. A gradual increase in IL-17 was found in STEMI and post-STEMI patients. Additionally, IL-17 had a powerful effect on the recruitment of CD14 ++ CD16 + /CD14 + CD16 ++ monocytes derived from patients post-STEMI compared with the monocytes from patients with STEMI, suggesting that IL-17 recruits monocytes with inflammatory activity post-STEMI. Furthermore, IL-17 increased the expression of TLR4 on CD14 + CD16 - and CD14 ++ CD16 + /CD14 + CD16 ++ monocytes post-STEMI and might enhance the response to danger-associated molecular patterns post-STEMI. Moreover, IL-17 induced secretion of IL-6 from CD14 ++ CD16 - and CD14 ++ CD16 + /CD14 + CD16 ++ monocytes both in STEMI and in post-STEMI, which indicates that IL-17 has an effect on the secretion of proinflammatory cytokines from monocytes during STEMI and post-STEMI. Overall, we demonstrate that in STEMI and post-STEMI, IL-17 is increased and induces the migration and activation of monocyte subsets, possibly contributing to the inflammatory response through TLR4 and IL-6 secretion., Competing Interests: The authors declare that no competing interests exist., (Copyright © 2020 Montserrat Guadalupe Garza-Reyes et al.)

Class-I restricted T cell-associated molecule (CRTAM) is a member of the immunoglobulin superfamily, and it is closely related to nectin-like protein. CRTAM is expressed in activated CD8 T cells, NKT cells, NK cells and in a subpopulation CD4 T cells. In this study, we produce as recombinant proteins, the Ig-domains of CRTAM (IgV-IgC), the IgV, and the IgC. These proteins were successfully purified in the soluble fraction only if the stalk region was included. The recombinant CRTAM recognizes its ligand nectin-like 2 in a cell-free system. We also demonstrate that the IgC domain of CRTAM is recognized by the anti-hCRTAM monoclonal antibody C8 with a 0.62 nM affinity. In conclusion, the stalk region of CRTAM provides solubility for the expression of its Ig-domains as recombinant proteins.

Understanding the mitotic DNA damage response (DDR) is critical to our comprehension of cancer, premature aging and developmental disorders which are marked by DNA repair deficiencies. In this study we use a micro-focused laser to induce DNA damage in selected mitotic chromosomes to study the subsequent repair response. Our findings demonstrate that (1) mitotic cells are capable of DNA repair as evidenced by DNA synthesis at damage sites, (2) Repair is attenuated when DNA-PKcs and ATM are simultaneously compromised, (3) Laser damage may permit the observation of previously undetected DDR proteins when damage is elicited by other methods in mitosis, and (4) Twenty five percent of mitotic DNA-damaged cells undergo a subsequent mitosis. Together these findings suggest that mitotic DDR is more complex than previously thought and may involve factors from multiple repair pathways that are better understood in interphase., Competing Interests: The authors have declared that no competing interests exist.

FSH exists as different glycoforms that differ in glycosylation of the hormone-specific β-subunit. Tetra-glycosylated FSH (FSH 24 ) and hypo-glycosylated FSH (FSH 18/21 ) are the most abundant glycoforms found in humans. Employing distinct readouts in HEK293 cells expressing the FSH receptor, we compared signaling triggered by human pituitary FSH preparations (FSH 18/21 and FSH 24 ) as well as by equine FSH ( e FSH), and human recombinant FSH ( rec FSH), each exhibiting distinct glycosylation patterns. The potency in eliciting cAMP production was greater for e FSH than for FSH 18/21 , FSH 24 , and rec FSH, whereas in the ERK1/2 activation readout, potency was highest for FSH 18/21 followed by e FSH, rec FSH, and FSH 24 . In β-arrestin1/2 CRISPR/Cas9 HEK293-KO cells, FSH 18/21 exhibited a preference toward β-arrestin-mediated ERK1/2 activation as revealed by a drastic decrease in pERK during the first 15-minute exposure to this glycoform. Exposure of β-arrestin1/2 KO cells to H89 additionally decreased pERK1/2, albeit to a significantly lower extent in response to FSH 18/21 . Concurrent silencing of β-arrestin and PKA signaling, incompletely suppressed pERK response to FSH glycoforms, suggesting that pathways other than those dependent on Gs-protein and β-arrestins also contribute to FSH-stimulated pERK1/2. All FSH glycoforms stimulated intracellular Ca 2+ (iCa 2+ ) accumulation through both influx from Ca 2+ channels and release from intracellular stores; however, iCa 2+ in response to FSH 18/21 depended more on the latter, suggesting differences in mechanisms through which glycoforms promote iCa 2+ accumulation. These data indicate that FSH glycosylation plays an important role in defining not only the intensity but also the functional selectivity for the mechanisms leading to activation of distinct signaling cascades., (© Endocrine Society 2020.)

B lymphocytes are recognized for their crucial role in the adaptive immunity since they represent the only leukocyte lineage capable of differentiating into Ab-secreting cells. However, it has been demonstrated that these lymphocytes can exert several Ab-independent functions, including engulfing and processing Ags for presentation to T cells, secreting soluble mediators, providing co-stimulatory signals, and even participating in lymphoid tissues development. Beyond that, several reports claiming the existence of multiple B cell subsets contributing directly to innate immune responses have appeared. These "innate-like" B lymphocytes, whose phenotype, development pathways, tissue distribution, and functions are in most cases notoriously different from those of conventional B cells, are crucial to early protective responses against pathogens by exerting "crossover" defensive strategies that blur the established boundaries of innate and adaptive branches of immunity. Examples of these mechanisms include the rapid secretion of the polyspecific natural Abs, increased susceptibility to innate receptors-mediated activation, cytokine secretion, downstream priming of other innate cells, usage of specific variable immunoglobulin gene-segments, and other features. As these new insights emerge, it is becoming preponderant to redefine the functionality of B cells beyond their classical adaptive-immune tasks., (©2018 Society for Leukocyte Biology.)

Tilmicosin is an antimicrobial agent used to treat intramammary infections against Staphylococcus aureus and has clinical anti-inflammatory effects. However, the mechanism by which it modulates the inflammatory process in the mammary gland is unknown. We evaluated the effect of tilmicosin treatment on the modulation of the mammary innate immune response after S. aureus infection and its effect on casein production in mammary epithelial cells. To achieve this goal, we used immortalized mammary epithelial cells (MAC-T), pretreated for 12 h or treated with tilmicosin after infection with S. aureus (ATCC 27543). Our data showed that tilmicosin decreases intracellular infection (P < 0.01) and had a protective effect on MAC-T reducing apoptosis after infection by 80% (P < 0.01). Furthermore, tilmicosin reduced reactive oxygen species (ROS) (P < 0.01), IL-1β (P < 0.01), IL-6 (P < 0.01), and TNF-α (P < 0.05) production. In an attempt to investigate the signaling pathways involved in the immunomodulatory effect of tilmicosin, mitogen-activated protein kinase (MAPK) phosphorylation was measured by fluorescent-activated cell sorting. Pretreatment with tilmicosin increased ERK1/2 (P < 0.05) but decreased P38 phosphorylation (P < 0.01). In addition, the anti-inflammatory effect of tilmicosin helped to preserve casein synthesis in mammary epithelial cells (P < 0.01). This result indicates that tilmicosin could be an effective modulator inflammation in the mammary gland. Through regulation of MAPK phosphorylation, ROS production and pro-inflammatory cytokine secretion tilmicosin can provide protection from cellular damage due to S. aureus infection and help to maintain normal physiological functions of the bovine mammary epithelial cell.

Intestinal macrophages are highly mobile cells with extraordinary plasticity and actively contribute to cytokine-mediated epithelial cell damage. The mechanisms triggering macrophage polarization into a proinflammatory phenotype are unknown. Here, we report that during inflammation macrophages enhance its intercellular adhesion properties in order to acquire a M1-phenotype. Using in vitro and in vivo models we demonstrate that intercellular adhesion is mediated by integrin-αVβ3 and relies in the presence of the unconventional class I myosin 1F (Myo1F). Intercellular adhesion mediated by αVβ3 stimulates M1-like phenotype in macrophages through hyperactivation of STAT1 and STAT3 downstream of ILK/Akt/mTOR signaling. Inhibition of integrin-αVβ3, Akt/mTOR, or lack of Myo1F attenuated the commitment of macrophages into a pro-inflammatory phenotype. In a model of colitis, Myo1F deficiency strongly reduces the secretion of proinflammatory cytokines, decreases epithelial damage, ameliorates disease activity, and enhances tissue repair. Together our findings uncover an unknown role for Myo1F as part of the machinery that regulates intercellular adhesion and polarization in macrophages.

Surface plasmon resonance (SPR)-based biosensors offer superior analytical features such as simplicity, sensitivity, and specificity when compared to conventional methods in clinical analyses. In addition, they deliver real-time monitoring of label-free analytes with high-throughput approaches requiring little sample pretreatment that allows the analysis of virtually every clinical sample type to determine the amount and/or activity of any molecule of interest. Accordingly, SPR emerges as a novel, efficient, powerful, and relatively low-cost alternative tool for routine clinical analysis, opening also new horizons for developments in personalized medicine applied to diagnostics or therapeutics' monitoring., (Copyright: © 2019 SecretarÍa de Salud.)

Immune tolerance, both to exogenous antigens and autoantigens, is essential for restraining undesired inflammatory responses that might result in severe damage to body tissues or cause chronic diseases. During the past few decades, different cell populations and molecules by them secreted have been associated with suppressing and regulatory mechanisms of immune responses. Although B cells typically acquire relevance as precursors of antibody-producing cells, they can also develop potent regulatory functions through the production of soluble molecules or by establishing direct cellular interactions mediated by different surface proteins implicated in signal transduction. While most studies of regulatory B cells define the role of these lymphocytes in autoimmune diseases, evidence of their importance and mechanisms of action in allergic diseases has accumulated in recent years. As a result, regulatory B cells appear to be relevant elements for the establishment or loss of allergen tolerance in different allergic diseases, although they still have been little explored.

Cells release several biomolecules to the extracellular environment using them as a communication alternative with neighbor cells. Besides these molecules, cells also release more complex elements, like vesicles; structures composed of a lipidic bilayer with transmembrane proteins that protect a hydrophilic content. Exosomes are a small subtype of vesicles (30-150 nm), produced by many cell types, such as tumor cells, neurons, epithelial cells and immune cells. Included in this last group, antigen presenting cells produce exosomes that contain different types of molecules depending on their activation and/or maturation state. In recent years there has been an exponential interest in exosomes due to the recent evidences that show the immunomodulatory properties of these vesicles and therefore, their great potential in diagnostic approaches and development of therapies for different inflammation-associated pathologies.

Although the production of antigen-specific antibodies has been the originally accepted function of B-cells during immune responses, specific subsets that can negatively regulate inflammation, designated regulatory B-cells (Bregs), have been identified recently. These immunosuppressive cells support tolerance, mainly through the production of interleukin 10 and other unconventional factors. There have been emerging data suggesting their importance in diverse normal and pathologic processes. Novel and in development B-cell targeted therapies seem to be ideal treatments for different types of diseasessuch as cancer and allergy. Here, we discuss the current knowledge on the implication of Bregs in autoimmunity- elated diseases, highlighting the importance of these cells for the development of novel strategies in the treatment of these pathologies.

Tetraspanins are a family of transmembrane proteins that form membrane microdomains. They play important roles in migration, adhesion and other cellular processes. TspanC8, a subfamily of tetraspanins, was found to associate and promote ADAM10 trafficking and cell surface localization. One of its members, Tspan33, is expressed in activated B cells. Using RT-PCR and flow cytometry, we analysed the pattern of expression of Tspan33 in B cells from healthy donors. We found Tspan33 expression in early and late stages of B cell development. However, Tspan33 expression did not correlate with ADAM10 surface expression. We also found expression of Tspan33 early in the activation process. Given its predominant expression in activated B cells and in several lymphomas, but not in naive B cells, we hypothesize that Tspan33 could be a potential target for therapeutic purposes., (© 2017 The Foundation for the Scandinavian Journal of Immunology.)

Posttranslational modifications occurring during the biosynthesis of G protein-coupled receptors include glycosylation and palmitoylation at conserved cysteine residues located in the carboxyl-terminus of the receptor. In a number of these receptors, these modifications play an important role in receptor function and particularly, in intracellular trafficking. In the present study, the three cysteine residues present in the carboxyl-terminus of the human FSHR were replaced with glycine by site-directed mutagenesis. Wild-type and mutant (Cys627/629/655Gly) FSHRs were then transiently expressed in HEK-293 cells and analyzed for cell-surface plasma membrane expression, agonist-stimulated signaling and internalization, and postendocytic processing in the absence and presence of lysosome and/or proteasome inhibitors. Compared with the wild-type FSHR, the triple mutant FSHR exhibited ~70% reduction in plasma membrane expression as well as a profound attenuation in agonist-stimulated cAMP production and ERK1/2 phosphorylation. Incubation of HEK-293 cells expressing the wild-type FSHR with 2-bromopalmitate (palmitoylation inhibitor) for 6 h, decreased plasma membrane expression of the receptor by ~30%. The internalization kinetics and β-arrestin 1 and 2 recruitment were similar between the wild-type and triple mutant FSHR as disclosed by assays performed in non-equilibrium binding conditions and by confocal microscopy. Cells expressing the mutant FSHR recycled the internalized FSHR back to the plasma membrane less efficiently than those expressing the wild-type FSHR, an effect that was counteracted by proteasome but not by lysosome inhibition. These results indicate that replacement of the cysteine residues present in the carboxyl-terminus of the FSHR, impairs receptor trafficking from the endoplasmic reticulum/Golgi apparatus to the plasma membrane and its recycling from endosomes back to the cell surface following agonist-induced internalization. Since in the FSHR these cysteine residues are S-palmitoylated, the data presented emphasize on this posttranslational modification as an important factor for both upward and downward trafficking of this receptor.

The X-linked hyper-IgM syndrome (XHIGM) is the most common form of HIGM. Patients are clinically diagnosed on the basis of recurrent sinopulmonary infections, accompanied with low levels of IgG and IgA, normal to elevated levels of IgM, and the presence of peripheral B cells. Here, we have reported a novel deletion of four nucleotides in CD40LG exon 3, c.375&#95;378delCAAA, which led to a frameshift mutation with a premature stop codon, p.Asn101*126. The deletion resulted in a truncated protein, in which majority of the extracellular domain was lost. However, detection of surface CD40L was still possible as the intracellular, transmembrane, and part of the extracellular domains were not affected. This indicated that this mutation did not affect protein stability and that immunodetection of CD40L expression is not enough for the diagnosis of XHIGM. Our study strongly suggests that genetic diagnosis for XHIGM should always be performed when clinical data support this diagnosis and CD40L protein is present.