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Congenital pseudarthrosis of the tibia (CPT) is a severe pathology marked by spontaneous bone fractures that fail to heal, leading to fibrous nonunion. Half of patients with CPT are affected by the multisystemic genetic disorder neurofibromatosis type 1 (NF1) caused by mutations in the NF1 tumor suppressor gene, a negative regulator of RAS-mitogen-activated protein kinase (MAPK) signaling pathway. Here, we analyzed patients with CPT and Prss56-Nf1 knockout mice to elucidate the pathogenic mechanisms of CPT-related fibrous nonunion and explored a pharmacological approach to treat CPT. We identified NF1 -deficient Schwann cells and skeletal stem/progenitor cells (SSPCs) in pathological periosteum as affected cell types driving fibrosis. Whereas NF1 -deficient SSPCs adopted a fibrotic fate, NF1 -deficient Schwann cells produced critical paracrine factors including transforming growth factor-β and induced fibrotic differentiation of wild-type SSPCs. To counteract the elevated RAS-MAPK signaling in both NF1 -deficient Schwann cells and SSPCs, we used MAPK kinase (MEK) and Src homology 2 containing protein tyrosine phosphatase 2 (SHP2) inhibitors. Combined MEK-SHP2 inhibition in vivo prevented fibrous nonunion in the Prss56-Nf1 knockout mouse model, providing a promising therapeutic strategy for the treatment of fibrous nonunion in CPT.

Chronic obstructive pulmonary disease (COPD) is a condition characterized by chronic airway inflammation and obstruction, primarily caused by tobacco smoking. Although the involvement of immune cells in COPD pathogenesis is well established, the contribution of innate lymphoid cells (ILCs) remains poorly understood. ILCs are a type of innate immune cells that participate in tissue remodeling processes, but their specific role in COPD has not been fully elucidated. During COPD, the breakdown of pulmonary elastin generates elastin peptides that elicit biological activities on immune cells. This study aimed to investigate the presence of ILC in patients with COPD and examine the impact of elastin peptides on their functionality. Our findings revealed an elevated proportion of ILC2 in the peripheral blood of patients with COPD, and a general activation of ILC as indicated by an increase in their cytokine secretion capacity. Notably, our study demonstrated that serum from patients with COPD promotes ILC2 phenotype, likely due to the elevated concentration of IL-5, a cytokine known to favor ILC2 activation. Furthermore, we uncovered that this increase in IL-5 secretion is partially attributed to its secretion by macrophages upon stimulation by elastin peptides, suggesting an indirect role of elastin peptides on ILC in COPD. These findings shed light on the involvement of ILC in COPD and provide insights into the potential interplay between elastin breakdown, immune cells, and disease progression. Further understanding of the mechanisms underlying ILC activation and their interaction with elastin peptides could contribute to the development of novel therapeutic strategies for COPD management. NEW & NOTEWORTHY Elastin-derived peptides, generated following alveolar degradation during emphysema in patients with COPD, are able to influence the response of type 2 innate lymphoid cells. We show that the orientation of innate lymphoid cells in patients with COPD is shifted toward a type 2 profile and that elastin peptides are indirectly participating in that shift through their influence of macrophages, which in turn impact innate lymphoid cells.

How infection by a viral variant showing antigenic drift impacts a preformed mature human memory B cell (MBC) repertoire remains an open question. Here, we studied the MBC response up to 6 months after SARS-CoV-2 Omicron BA.1 breakthrough infection in individuals previously vaccinated with three doses of the COVID-19 mRNA vaccine. Longitudinal analysis, using single-cell multi-omics and functional analysis of monoclonal antibodies from RBD-specific MBCs, revealed that a BA.1 breakthrough infection mostly recruited pre-existing cross-reactive MBCs with limited de novo response against BA.1-restricted epitopes. Reorganization of clonal hierarchy and new rounds of germinal center reactions, however, combined to maintain diversity and induce progressive maturation of the MBC repertoire against common Hu-1 and BA.1, but not BA.5-restricted, SARS-CoV-2 Spike RBD epitopes. Such remodeling was further associated with a marked improvement in overall neutralizing breadth and potency. These findings have fundamental implications for the design of future vaccination booster strategies., Competing Interests: Declaration of interests Outside of the submitted work, M. Mahévas received research funds from GSK and personal fees from LFB and Amgen. J.-C.W. received consulting fees from Institut Mérieux. P.B. received consulting fees from Regeneron Pharmaceuticals., (Copyright © 2023 Elsevier Inc. All rights reserved.)

X-linked chronic granulomatous disease (CGD) is associated with defective phagocytosis, life-threatening infections, and inflammatory complications. We performed a clinical trial of lentivirus-based gene therapy in four patients (NCT02757911). Two patients show stable engraftment and clinical benefits, whereas the other two have progressively lost gene-corrected cells. Single-cell transcriptomic analysis reveals a significantly lower frequency of hematopoietic stem cells (HSCs) in CGD patients, especially in the two patients with defective engraftment. These two present a profound change in HSC status, a high interferon score, and elevated myeloid progenitor frequency. We use elastic-net logistic regression to identify a set of 51 interferon genes and transcription factors that predict the failure of HSC engraftment. In one patient, an aberrant HSC state with elevated CEBPβ expression drives HSC exhaustion, as demonstrated by low repopulation in a xenotransplantation model. Targeted treatments to protect HSCs, coupled to targeted gene expression screening, might improve clinical outcomes in CGD., Competing Interests: Declaration of interests S.S., L.M., A.C., A.D., A. Guilloux, A.R., M.C., and E.S. have submitted a patent related to the use of the predictive markers for assessing HSC exhaustion induced by chronic inflammation (EP22305722.5 filed on May 16, 2022)., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The SARS-CoV-2 Omicron variant can escape neutralization by vaccine-elicited and convalescent antibodies. Memory B cells (MBCs) represent another layer of protection against SARS-CoV-2, as they persist after infection and vaccination and improve their affinity. Whether MBCs elicited by mRNA vaccines can recognize the Omicron variant remains unclear. We assessed the affinity and neutralization potency against the Omicron variant of several hundred naturally expressed MBC-derived monoclonal IgG antibodies from vaccinated COVID-19-recovered and -naive individuals. Compared with other variants of concern, Omicron evaded recognition by a larger proportion of MBC-derived antibodies, with only 30% retaining high affinity against the Omicron RBD, and the reduction in neutralization potency was even more pronounced. Nonetheless, neutralizing MBC clones could be found in all the analyzed individuals. Therefore, despite the strong immune escape potential of the Omicron variant, these results suggest that the MBC repertoire generated by mRNA vaccines still provides some protection against the Omicron variant in vaccinated individuals., Competing Interests: Declaration of interests Outside of the submitted work, M. Mahévas received research funds from GSK and personal fees from LFB and Amgen. J.-C.W. received consulting fees from Institut Mérieux. P.B. received consulting fees from Regeneron Pharmaceuticals. J.-M.P. received personal fees from Abbvie, Gilead, Merck, and Siemens Healthcare. F.A.R. is a member of the board of MELETIOS Therapeutics and of the Scientific Advisory Board of eureKARE., (Copyright © 2022. Published by Elsevier Inc.)

Phenotyping intramuscular immune cells is essential for the characterization of dysimmune/inflammatory myopathies (DIM). Flow cytometry (FC) is the most reliable technique for analyzing leukocyte subpopulations and evaluating their activation levels. We developed a purely mechanical protocol for extracting cells from muscle tissue allowing us to preserve cell surface epitopes and determined its applicability to experimental pathology in mice and myopathological diagnosis in human. Skeletal muscle regeneration in mice was associated with a transient enrichment of macrophages (CD11bhighGr-1+), myeloid dendritic cells (CD3-C8+CD11bhigh), CD8+ T cells (CD3+C8+), and NK cells (CD3- CD11bhighNKp46+). In murine models of inherited muscle dystrophies, leukocytes represented 23%-84% of intramuscular mononuclear cells, with a percentage of CD8+ T cells (4%-17%) mirroring that of all CD45+ cells, while MDCs remained a minority. In human 16 samples (DIM: n = 9; nonimmune conditions: n = 7), DIM was associated with intramuscular recruitment of CD8+ T cells, but not CD4+ T cells and NK cells. FC allowed concomitant quantification of HLA-DR, CD25, CD38, and CD57 activation/differentiation biomarkers and showed increased activation levels of CD4+ and CD8+ T cells in DIM. In conclusion, FC is an appropriate method for quantifying intramuscular leukocyte subpopulations and analyzing their activation states., (© The Author(s) 2022. Published by Oxford University Press on behalf of American Association of Neuropathologists, Inc. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Large granular lymphocytic leukemia (LGLL) is a rare clonal lymphoproliferative disorder from T or NK origin., Purpose: to report on the diagnostic and therapeutic management of LGLL investigated in the university hospital at Nancy, France., Methods: retrospective (7 years) collection of clinical and biological data and patients' cohort analysis., Results: Eight out of fifteen patients presented with neutropenia, including five profound neutropenia (neutrophils < 500 × 10 9 /L). Four patients had an infection. Two patients have rheumatoid arthritis and an associated Felty's syndrome, one a Sweet syndrome. Two also suffered from chronic Lymphocytic Leukemia, and one from a diffuse large B-cell lymphoma. Twelve patients had LGLL-T and 3 had a chronic LGLL-NK. Eleven out of twelve patients had a clonal LGLL-T when polymerase chain reaction assessed. No KIR clonality was sought among the 3 LGL-NK patients. Five patients out of fifteen received immunosuppressive treatment., Conclusion: Although using simple and robust investigations, our series demonstrates a high heterogeneity in LGLL detection and assessment.

In addition to serum immunoglobulins, memory B cell (MBC) generation against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is another layer of immune protection, but the quality of MBC responses in naive and coronavirus disease 2019 (COVID-19)-recovered individuals after vaccination remains ill defined. We studied longitudinal cohorts of naive and disease-recovered individuals for up to 2 months after SARS-CoV-2 mRNA vaccination. We assessed the quality of the memory response by analysis of antibody repertoires, affinity, and neutralization against variants of concern (VOCs) using unbiased cultures of 2,452 MBCs. Upon boosting, the MBC pool of recovered individuals expanded selectively, matured further, and harbored potent neutralizers against VOCs. Although naive individuals had weaker neutralizing serum responses, half of their RBD-specific MBCs displayed high affinity toward multiple VOCs, including delta (B.1.617.2), and one-third retained neutralizing potency against beta (B.1.351). Our data suggest that an additional challenge in naive vaccinees could recall such affinity-matured MBCs and allow them to respond efficiently to VOCs., Competing Interests: Declaration of interests Outside of the submitted work, M. Mahévas. received research funds from GSK and personal fees from LFB and Amgen. J.-C.W. received consulting fees from Institut Mérieux. P.B. received consulting fees from Regeneron Pharmaceuticals. J.-M.P. received personal fees from Abbvie, Gilead, Merck, and Siemens Healthcare. F.R. is a member of the board of MELETIOS Therapeutics and of the Scientific Advisory Board of eureKARE., (Copyright © 2021. Published by Elsevier Inc.)

The Sezary syndrome has been defined by a triad combining erythrodermia, generalized lymphadenopathy, and the presence of circulating Sezary cells > 1 × 10 9 /L characterized by a CD4+/CD8- phenotype with loss of one or more T antigens (mainly CD7 and/or CD26). We retrospectively reviewed the immunophenotypic profiles of 10 SS patients followed in our institution (University Hospital at Nancy, France). The application of the WHO criteria resulted in a diagnostic confirmation for 9 out of 10 cases. Since 2008, new diagnostic and staging criteria have been proposed, including the CD158k/KIR3DL2 receptor detection. The application of these new criteria to our cohort led us to notice a phenotypic heterogeneity of our cases but allowed to achieve a relevant diagnosis of Sezary syndrome in all cases, especially for patients with lymphopenia. The use of such a panel of monoclonal antibodies also optimized the follow-up of the patients.

Memory B cells play a fundamental role in host defenses against viruses, but to date, their role has been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory B cells, including pre-existing cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and largely contributed to the late, remarkably stable, memory B cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6 months after SARS-CoV-2 infection and may provide long-term protection., Competing Interests: Declaration of interests M. Mahévas received research funds from GlaxoSmithKline, outside of the submitted work, and personal fees from LFB and Amgen, outside of the submitted work. J.-C.W. received consulting fees from Institut Mérieux, outside of the submitted work. J.-M.P. received personal fees from Abbvie, Gilead, Merck, and Siemens Healthcare, outside of the submitted work., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Little is known about the time-dependent immune responses in severe COVID-19. Data of 15 consecutive patients were sequentially recorded from intensive care unit admission. Lymphocyte subsets and total monocyte and subsets counts were monitored as well as the expression of HLA-DR. For 5 patients, SARS-CoV-2-specific T-cell polyfunctionality was assessed against Spike and Nucleoprotein SARS-CoV-2 peptides. Non-specific inflammation markers were increased in all patients. Median monocyte HLA-DR expression was below the 8,000 AB/C threshold defining acquired immunodepression. A "V" trend curve for lymphopenia, monocyte numbers, and HLA-DR expression was observed with a nadir between days 11 and 14 after symptoms' onset. Intermediate CD14 ++ CD16 + monocytes increased early with a reduction in classic CD14 ++ CD16 - monocytes. Polyfunctional SARS-Cov-2-specific CD4 T-cells were present and functional, whereas virus-specific CD8 T-cells were less frequent and not efficient. We report a temporal variation of both innate and adaptive immunity in severe COVID-19 patients, helpful in guiding therapeutic decisions (e.g. anti-inflammatory vs. immunostimulatory ones). We describe a defect in virus-specific CD8 T-cells, a potential biomarker of clinical severity. These combined data also provide helpful knowledge for vaccine design., Clinical Trial Registration: https://clinicaltrials.gov/, identifier NCT04386395., (Copyright © 2020 Payen, Cravat, Maadadi, Didelot, Prosic, Dupuis, Losser and De Carvalho Bittencourt.)

Background & Aims: Approximately 75% of patients with suspected Lynch syndrome carry variants in MLH1 or MSH2, proteins encoded by these genes are required for DNA mismatch repair (MMR). However, 30% of these are variants of unknown significance (VUS). A assay that measures cell response to the cytotoxic effects of a methylating agent can determine the effects of VUS in MMR genes and identify patients with constitutional MMR-deficiency syndrome. We adapted this method to test the effects of VUS in MLH1 and MSH2 genes found in patients with suspected Lynch syndrome., Methods: We transiently expressed MLH1 or MSH2 variants in MLH1- or MSH2-null human colorectal cancer cell lines (HCT116 or LoVo), respectively. The MMR process causes death of cells with methylation-damaged DNA bases, so we measured proportions of cells that undergo death following exposure to the methylating agent; cells that escaped its toxicity were considered to have variants that affect function of the gene product. Using this assay, we analyzed 88 variants (mainly missense variants), comprising a validation set of 40 previously classified variants (19 in MLH1 and 21 in MSH2) and a prospective set of 48 VUS (25 in MLH1 and 23 in MSH2). Prediction scores were calculated for all VUS according to the recommendations of the American College of Medical Genetics and Genomics, based on clinical, somatic, in silico, population, and functional data., Results: The assay correctly classified 39 of 40 variants in the validation set. The assay identified 12 VUS that did alter function of the gene product and 28 VUS that did not; the remaining 8 VUS had intermediate effects on MMR capacity and could not be classified. Comparison of assay results with prediction scores confirmed the ability of the assay to discriminate VUS that affected the function of the gene products from those that did not., Conclusions: Using an assay that measures the ability of the cells to undergo death following DNA damage induction by a methylating agent, we were able to assess whether variants in MLH1 and MSH2 cause defects in DNA MMR. This assay might be used to help assessing the pathogenicity of VUS in MLH1 and MSH2 found in patients with suspected Lynch syndrome., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Previous data have suggested that B-cell-depletion therapy may induce the settlement of autoreactive long-lived plasma cells (LLPCs) in the spleen of patients with autoimmune cytopenia. To investigate this process, we used the AID-CreERT2-EYFP mouse model to follow plasma cells (PCs) engaged in an immune response. Multiplex polymerase chain reaction at the single-cell level revealed that only a small fraction of splenic PCs had a long-lived signature, whereas PCs present after anti-CD20 antibody treatment appeared more mature, similar to bone marrow PCs. This observation suggested that, in addition to a process of selection, a maturation induced on B-cell depletion drove PCs toward a long-lived program. We showed that B-cell activating factor (BAFF) and CD4 + T cells play a major role in the PC survival niche, because combining anti-CD20 with anti-BAFF or anti-CD4 antibody greatly reduce the number of splenic PCs. Similar results were obtained in the lupus-prone NZB/W model. These different contributions of soluble and cellular components of the PC niche in the spleen demonstrate that the LLPC expression profile is not cell intrinsic but largely depends on signals provided by the splenic microenvironment, implying that interfering with these components at the time of B-cell depletion might improve the response rate in autoimmune cytopenia., (© 2018 by The American Society of Hematology.)

Objective: Plasma phospholipid transfer protein (PLTP) is a key determinant of lipoprotein metabolism, and both animal and human studies converge to indicate that PLTP promotes atherogenesis and its thromboembolic complications. Moreover, it has recently been reported that PLTP modulates inflammation and immune responses. Although earlier studies from our group demonstrated that PLTP can modify macrophage activation, the implication of PLTP in the modulation of T-cell-mediated immune responses has never been investigated and was therefore addressed in the present study. Approach and results: In the present study, we demonstrated that PLTP deficiency in mice has a profound effect on CD4 + Th0 cell polarization, with a shift towards the anti-inflammatory Th2 phenotype under both normal and pathological conditions. In a model of contact hypersensitivity, a significantly impaired response to skin sensitization with the hapten-2,4-dinitrofluorobenzene (DNFB) was observed in PLTP-deficient mice compared to wild-type (WT) mice. Interestingly, PLTP deficiency in mice exerted no effect on the counts of total white blood cells, lymphocytes, granulocytes, or monocytes in the peripheral blood. Moreover, PLTP deficiency did not modify the amounts of CD4 + and CD8 + T lymphocyte subsets. However, PLTP-deficiency, associated with upregulation of the Th2 phenotype, was accompanied by a significant decrease in the production of the pro-Th1 cytokine interleukin 18 by accessory cells., Conclusions: For the first time, this work reports a physiological role for PLTP in the polarization of CD4 + T cells toward the pro-inflammatory Th1 phenotype.

Hidradenitis suppurativa (HS) is a chronic, inflammatory, debilitating, follicular disease of the skin. Despite a high prevalence in the general population, the physiopathology of HS remains poorly understood. The use of antibiotics and immunosuppressive agents for therapy suggests a deregulated immune response to microflora. Using cellular and gene expression analyses, we found an increased number of infiltrating CD4(+) T cells secreting IL-17 and IFN-γ in perilesional and lesional skin of patients with HS. By contrast, IL-22-secreting CD4(+) T cells are not enriched in HS lesions contrasting with increased number of those cells in the blood of patients with HS. We showed that keratinocytes isolated from hair follicles of patients with HS secreted significantly more IL-1β, IP-10, and chemokine (C-C motif) ligand 5 (RANTES) either constitutively or on pattern recognition receptor stimulations. In addition, they displayed a distinct pattern of antimicrobial peptide production. These findings point out a functional defect of keratinocytes in HS leading to a balance prone to inflammatory responses. This is likely to favor a permissive environment for bacterial infections and chronic inflammation characterizing clinical outcomes in patients with HS., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Dense granule disorder is one of the most common platelet abnormalities, resulting from dense granule deficiency or secretion defect. This study was aimed to evaluate the clinical usefulness of the flow cytometric combination of mepacrine uptake/release assay and CD63 expression detection in the management of patients with suspected dense granule disorder. Over a period of 5 years, patients with abnormal platelet aggregation and/or reduced adenosine triphosphate (ATP) secretion suggestive of dense granule disorder were consecutively enrolled. The flow cytometric assays were systematically performed to further investigate dense granule functionality. Among the 26 included patients, 18 cases showed impaired mepacrine uptake/release and reduced CD63 expression on activated platelets, consistent with δ-storage pool deficiency (SPD). Another seven patients showed decrease in mepacrine release and CD63 expression but mepacrine uptake was normal, indicating secretion defect rather than δ-SPD. Unfortunately, ATP secretion could not be measured in 7 out of the 26 patients due to insufficient sample and/or severe thrombocytopenia. This test combination provides a rapid and effective method to detect the heterogeneous abnormalities of platelet dense granule by distinguishing between storage and release defects. This combination is particularly advantageous for severely thrombocytopenic patients and pediatric patients in which only minimal sample is required., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: A longstanding goal in regenerative medicine is to reconstitute functional tissues or organs after injury or disease. Attention has focused on the identification and relative contribution of tissue specific stem cells to the regeneration process. Relatively little is known about how the physiological process is regulated by other tissue constituents. Numerous injury models are used to investigate tissue regeneration, however, these models are often poorly understood. Specifically, for skeletal muscle regeneration several models are reported in the literature, yet the relative impact on muscle physiology and the distinct cells types have not been extensively characterised., Methods: We have used transgenic Tg:Pax7nGFP and Flk1GFP/+ mouse models to respectively count the number of muscle stem (satellite) cells (SC) and number/shape of vessels by confocal microscopy. We performed histological and immunostainings to assess the differences in the key regeneration steps. Infiltration of immune cells, chemokines and cytokines production was assessed in vivo by Luminex®., Results: We compared the 4 most commonly used injury models i.e. freeze injury (FI), barium chloride (BaCl2), notexin (NTX) and cardiotoxin (CTX). The FI was the most damaging. In this model, up to 96% of the SCs are destroyed with their surrounding environment (basal lamina and vasculature) leaving a "dead zone" devoid of viable cells. The regeneration process itself is fulfilled in all 4 models with virtually no fibrosis 28 days post-injury, except in the FI model. Inflammatory cells return to basal levels in the CTX, BaCl2 but still significantly high 1-month post-injury in the FI and NTX models. Interestingly the number of SC returned to normal only in the FI, 1-month post-injury, with SCs that are still cycling up to 3-months after the induction of the injury in the other models., Conclusions: Our studies show that the nature of the injury model should be chosen carefully depending on the experimental design and desired outcome. Although in all models the muscle regenerates completely, the trajectories of the regenerative process vary considerably. Furthermore, we show that histological parameters are not wholly sufficient to declare that regeneration is complete as molecular alterations (e.g. cycling SCs, cytokines) could have a major persistent impact.

Primary warm autoimmune hemolytic anemia (wAIHA) is a rare autoimmune disease in which red blood cells are eliminated by IgG autoantibodies. We analyzed the antibody-secreting cells in the spleen and the peripheral blood of wAIHA patients in various contexts of treatment. Plasmablasts were observed in peripheral blood of newly diagnosed wAIHA patients and, accordingly, active germinal center reactions were present in the spleen of patients receiving short-term corticosteroid therapy. Long-term corticosteroid regimens markedly reduced this response while splenic plasma cells were able to persist, a fraction of them secreting anti-red blood cell IgG in vitro. In wAIHA patients treated by rituximab and who underwent splenectomy because of treatment failure, plasma cells were still present in the spleen, some of them being autoreactive. By using a set of diagnostic genes that allowed us to assess the plasma cell maturation stage, we observed that these cells displayed a long-lived program, differing from the one of plasma cells from healthy donors or from wAIHA patients with various immunosuppressant treatments, and more similar to the one of normal long-lived bone-marrow plasma cells. Interestingly, an increased level of B-cell activating factor (BAFF) was observed in the supernatant of spleen cell cultures from such rituximab-treated wAIHA patients. These results suggest, in line with our previous report on primary immune thrombocytopenia, that the B-cell depletion induced by rituximab promoted a suitable environment for the maturation and survival of auto-immune long-lived plasma cells in the spleen., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Massive loss of lamina propria CD4(+) T cells, changes in the lymphatic architecture, and altered intestinal epithelial barrier leading to microbial translocation are the common features of HIV-1 infection and are not fully restored under combined antiretroviral therapy (cART). To better understand determinants of gut mucosal restoration, we have performed phenotypic and gene expression analyses of the gut from HIV-infected patients, naive or treated with cART initiated either at the early phase of the primary infection or later during the chronic phase. We found a depletion of T helper type 22 (Th22) and interleukin-17-producing cells in naive patients. These populations, except Th22 cells, were not restored under cART. Regulatory T cells/Th17 ratio was significantly increased in HIV-infected patients and was inversely correlated to the restoration of CD4(+) T cells but not to gut HIV DNA levels. Gene profile analysis of gut mucosal distinguished two groups of patients, which fitted with the timing of cART initiation. In their majority early, but not later treated patients, exhibited conserved intestinal lymphoid structure, epithelial barrier integrity and dendritic cell maturation pathways. Our data demonstrate that early initiation of cART helps to preserve and/or restore lymphoid gut mucosal homeostasis and provide a rationale for initiating cART during the acute phase of HIV infection.

Experimental genetics have been widely used to explore the biology of the malaria parasites. The rodent parasites Plasmodium berghei and less frequently P. yoelii are commonly utilised, as their complete life cycle can be reproduced in the laboratory and because they are genetically tractable via homologous recombination. However, due to the limited number of drug-selectable markers, multiple modifications of the parasite genome are difficult to achieve and require large numbers of mice. Here we describe a novel strategy that combines positive-negative drug selection and flow cytometry-assisted sorting of fluorescent parasites for the rapid generation of drug-selectable marker-free P. berghei and P. yoelii mutant parasites expressing a GFP or a GFP-luciferase cassette, using minimal numbers of mice. We further illustrate how this new strategy facilitates phenotypic analysis of genetically modified parasites by fluorescence and bioluminescence imaging of P. berghei mutants arrested during liver stage development.

Homozygous mutations in EVER genes cause epidermodysplasia verruciformis (EV), characterized by an immune defect and the development of skin cancers associated with β-human papillomavirus (HPV) infections. The effects of EVER protein loss on the keratinocyte immune response remain unknown. We show here that EVER2 plays a critical role in the interplay between the NF-κB and JNK/AP-1 signaling pathways. EVER2-deficient cells overproduce IL-6 following the upregulation of JNK activation. They respond poorly to phorbol ester and TNF via the NF-κB pathway. They have lower levels of IKKα subunit, potentially accounting for impairments of p100 processing and the alternative NF-κB pathway. The loss of EVER2 is associated with an unusual TRAF protein profile. We demonstrate that EVER2 deficiency sustains TRAF2 ubiquitination and decreases the pool of TRAF2 available in the detergent-soluble fraction of the cell. Finally, we demonstrate that EVER2 loss induces constitutive PKCα-dependent c-jun phosphorylation and facilitates activation of the HPV5 long control region through a JNK-dependent pathway. These findings indicate that defects of the EVER2 gene may create an environment conducive to HPV replication and the persistence of lesions with the potential to develop into skin cancer.