Clinical and experimental immunology最新文献

Lysophosphatidic acid (LPA) is a crucial bioactive lipid mediator involved in various physiological processes; however, its role in macrophage polarization remains poorly understood; therefore, this study aimed to elucidate the modulatory effect of LPA on macrophage polarization, particularly its ability to shift M1 macrophages towards an M2-like phenotype, using murine macrophage RAW264.7 cells to confirm the expression of LPA receptor 1 (LPAR1) through immunofluorescence staining, which revealed that treatment of resting MO macrophages with LPA decreased inflammatory cytokines (IL-6, TNF-α) and increased TGF-β, with similar effects observed in LPS-stimulated cells and reversed by the LPAR1 inhibitor AM095, and immunostaining demonstrated a notable shift from an M1- to M2-like phenotype, as evidenced by an increase in the arginase-1/CD68 ratio; furthermore, LPA significantly decreased lactate production and increased ATP production in M1 macrophages, promoting a shift towards oxidative phosphorylation and suggesting metabolic reprogramming towards an M2-like phenotype, significantly influencing macrophage polarization and promoting a shift from a pro-inflammatory M1-like phenotype to an anti-inflammatory M2-like phenotype; these results suggest that treatment with LPA may help ameliorate diseases characterized by aberrant macrophage polarization, providing insights for the development of potential therapeutic strategies for inflammatory and autoimmune diseases.

Patients with systemic lupus erythematosus (SLE) exhibit significant susceptibility to severe bacterial infections, a leading cause of mortality. A key host defence mechanism is immunothrombosis, wherein activated monocytes rapidly upregulate tissue factor (TF) to initiate localized fibrin deposition that traps and contains pathogens. Effective immunothrombosis is therefore critical for preventing microbial dissemination. This process appears deficient in SLE, a disease defined by a systemic prothrombotic state, yet poor infection outcomes. A recently discovered molecular interaction suggests that TF directly binds to the interferon-α receptor (IFNAR1), acting as a rheostat to suppress interferon signalling. We hypothesize that in SLE, this regulatory axis is disrupted. The dominant, sustained interferon-stimulated gene (ISG) signatures in monocytes limit their capacity for TF upregulation in response to bacterial challenge, thereby impairing immunothrombosis and compromising bacterial containment. Supporting this, SLE patients with secondary antiphospholipid syndrome who have lower interferon signatures display markedly elevated TF levels and a different thrombotic profile, demonstrating the inverse relationship in a clinical subset. Furthermore, TF induction in monocytes is glycolysis-dependent, and SLE monocytes are known to have profound metabolic alterations. The chronic interferon state may thus impose a metabolic constraint that further limits the bioenergetic capacity for a robust TF response. Therefore, the confluence of interferon-driven suppression and metabolic dysfunction in SLE monocytes provides a compelling explanation for the failure of immunothrombosis, directly linking a core disease feature to infection susceptibility.

Functional approaches to properly examine individual's susceptibility to complement dysregulation are limited. We assessed ex vivo complement activation induced by sera from 38 healthy donors on resting microvascular endothelial cells with or without complement dysregulation (OX-24 monoclonal antibody). Following incubation, immunofluorescence was used to quantify membrane-bound C3b/iC3b and C5b-9 with a computer-assisted method (H-score). C3a and C5a anaphylatoxins were quantified in supernatants by ELISA. Genetic sequencing of 32 donors was also performed to identify variants in alternative pathway genes. Elevated complement deposition was defined by H-scoreC3c > 50 and/or H-scoreC5b-9 > 30. Combined analysis of C3b/iC3b and C5b-9 deposition in 35 donors showed that one donor (2.8%) had an isolated increase in C3b/iC3b deposits, three (8.6%) had an isolated increase in C5b-9 deposits, and one (2.8%) had both increased C3b/iC3b and C5b-9 deposition. Genetic analysis revealed three heterozygous rare/low frequency missense variants in CFH (p.N1050Y, p.R1210C) and CFI (p.A76G) in 3/5 donors with increased complement deposition. This model revealed distinct patterns of complement activation among healthy individuals and identified a genetic basis for dysregulation in three cases. This assay offers a promising tool to study complement activity and its mechanisms in research.

Introduction: We describe the immunophenotyping and genetic analysis of HIV-uninfected apparently immunocompetent adults presenting with disseminated cryptococcosis. Cryptococci are environmentally ubiquitous fungi that may cause disseminated infection including meningitis. Cryptococcosis occurs predominantly in immunocompromised hosts and most commonly in the context of human immunodeficiency virus (HIV) infection. In apparently immunocompetent patients, cryptococcal disease is rare, often diagnosed later and associated with higher mortality. The immunologic work-up and management of this patient group is challenging and poorly studied.

Methods: Between 2015-2021, eight apparently immunocompetent adults at the time of diagnosis with cryptococcosis underwent extensive diagnostic immunological work-up including T-/B-cell subsets, immunoglobulins, T-cell proliferation and phenotyping, serum-specific antibody responses, mannose binding lectin, measurement of selected cytokines, anti-cytokine autoantibodies and targeted genetic next-generation sequencing.

Results: The production of interleukin (IL)-17 following phytohaemagglutinin (PHA) stimulation was significantly reduced in all eight patients with cryptococcosis compared to healthy controls (median IL-17 concentration in whole blood stimulation assay 88.1pg/mL in patients; 452.1pg/mL in controls, p=0.0047). In 5/5 patients tested, the percentage of CD4+ T-cells positive for IL-17, including memory CD4+CD45RO+ IL-17+ T-cells, after stimulation with staphylococcal enterotoxin B (SEB) was significantly reduced (<=0.4% cells). Reduced IgM+ memory B-cells were noted in 4/5 tested. 4/8 patients were found to have CD4 lymphopaenia. One patient with Cryptococcus gattii infection had autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF). No underlying genetic causes were identified.

Conclusion: Patients had several immunological risk factors, but reduced IL-17 production was a striking feature across the cohort - a phenotype that may facilitate tailored immunotherapeutic approaches.Graphical Abstract.

Gamma-aminobutyric acid receptors (GABARs) primarily function by suppressing inflammatory responses, modulating neuronal excitability, and maintaining intracellular homeostasis, whereas N-methyl-D-aspartate receptors (NMDARs) play a key role in mediating pathological processes through the regulation of excitatory neurotransmission and immune responses. Viral infections have the capacity to modify the expression and functionality of these receptors, either directly or indirectly, thereby contributing to dysregulation within the neurological and immune systems and triggering a range of disease states. This review offers a comprehensive analysis of the mechanisms through which various viral infections interact with GABARs and NMDARs, emphasizing the possible intricate roles these receptors play in viral pathogenesis. Additionally, it underscores their potential as therapeutic targets for antiviral interventions, particularly in addressing immune dysregulation and neurological disorders.

Introduction: Murine studies have demonstrated that lymph node fibroblasts can present self-antigens via major histocompatibility complex class II molecules, inducing functional regulatory T cells and contributing to peripheral tolerance.

Methods: To investigate this phenomenon in humans, we developed an in vitro system co-culturing human lymph node fibroblasts with autologous CD4+ T cells.

Results: Our results reveal that lymph node fibroblasts upregulate human leukocyte antigen-DR (HLA-DR) upon contact with CD4+ T cells and maintain FoxP3+ regulatory T cells. This maintenance is lost upon blockade of HLA-DR or interleukin-2, and regulatory T cells are lost in the absence of lymph node fibroblasts. Furthermore, we demonstrate that lymph node fibroblasts directly isolated from rheumatoid arthritis patients exhibit a significant reduction in the frequency of HLA-DR+ cells compared to those from individuals at risk of developing the disease.

Conclusion: These findings highlight a crucial role for HLA-DR-expressing lymph node fibroblasts in maintaining peripheral tolerance within lymph nodes, a function that may be impaired in autoimmunity. Our study provides novel insights into the intricate cellular interactions within human lymph nodes and their potential implications in autoimmune disorders, opening new avenues for understanding and potentially treating these conditions.

Introduction: Despite the high global prevalence of Mycobacterium tuberculosis (Mtb) infection in humans, most infected individuals achieve a stable immunological equilibrium, without showing clinical signs and symptoms of tuberculosis (TB). Although the role of antibodies in TB is assumed to be relatively small compared to cell-mediated immunity, their role in TB has been documented in a few recent studies.

Methods: In this cross-sectional study, we quantitated antibody responses to Mtb antigens, lipoarabinomannan (LAM), and heparin-binding hemagglutinin adhesin (HBHA) by determining antigen-specific immunoglobulin A(IgA) and G(IgG) secretion levels using enzyme-linked immunosorbent assay (ELISA) in serum and saliva of pulmonary TB patients (PTB), their household contacts (HHC), and community controls (CC) (determined by QuantiFERON TB Gold assay QFT- test result).

Results: The HBHA-specific IgA levels were significantly higher in both saliva and serum in HHC groups compared to PTB patients (P=0.013, P=0.023). Exposed contacts, who were QFT-negative had higher serum HBHA-specific IgA responses compared to PTB patients (P=0.04). QFT-negative HHC and QFT-positive CC showed higher HBHA and LAM-specific IgG responses (P=0.006, P=0.002, P=0.0009, P=0.006, respectively) than PTB patients. Generally, LAM and HBHA-specific IgA levels were significantly higher in saliva compared to serum (P<0.0001) in all study groups.

Conclusion: Overall, the observed higher levels of IgA and IgG in controls, and exposed but QFT-negative contacts suggest a correlation with, and perhaps a role for these antibodies in preventing the development of active TB. The findings highlighted the potential involvement of saliva IgA in the immune response to Mtb, underscoring the relevance of mucosal immunity in TB infection.

T cells are one of the main drivers of inflammatory bowel diseases (IBD). Infliximab (IFX) is used in the treatment of IBD as an anti-inflammatory drug to induce remission by neutralizing TNFα. We determined the individual chemokine/homing receptor and cytokine profile in pediatric IBD patients before and during IFX therapy to identify predictive biomarkers for therapy success. Peripheral blood CD4+ cells from pediatric patients with IBD were immunomagnetically isolated and either directly analyzed by FACS for cell distribution and chemokine/homing receptor expression or evaluated for cytokine production after in-vitro-stimulation. Twenty-one responders (RS) and 21 non-responders (NRS) were recruited. Before IFX therapy, flow cytometry revealed decreased percentages of naïve conventional T cells in pediatric IBD patients. The proportions of CD62-L+ T cells were decreased in both CD and UC therapy responders. The cytokine profile of T cells was highly altered in IBD patients compared to healthy controls (HC). During IFX therapy, the frequencies of conventional memory and regulatory memory T cells expanded in both cohorts. IFX response was marked by a decrease of α4β7+ and IFNγ+ memory T cells in both CD and UC. In contrast, frequencies of Lag-3+ T cells proved to be significantly increased in NRS. These observations were irrespective of the underlying disease. T cells of pediatric IBD patients display an activated and rather Th1/Th17-shifted phenotype. The increased expression of the checkpoint molecule Lag-3 on T cells of NRS resembles a more exhausted phenotype than in RS and HC which appeared to be a relevant predictive marker for therapy failure.

Multiple Sclerosis (MS) is a complex auto-inflammatory disease affecting the brain and spinal cord, which results in axonal de-myelination and symptoms including fatigue, pain, and difficulties with vision and mobility. The involvement of the immune system in the pathology of MS is well established, particularly the adaptive T cell response, and there has been a particular focus on the IL-17-producing subset of Th17 cells and their role in driving disease. However, the importance of innate immune cells has not been so well characterized. Here we focussed on neutrophils, which are innate immune cells and rapid responders to inflammation, and which have recently been linked to other chronic autoimmune conditions. Multiple strands of evidence in patients with MS and in mice with the experimental autoimmune encephalomyelitis MS model suggest neutrophils may play a role in driving MS inflammation. Here, we performed proteomic analysis on neutrophils from patients with MS and healthy donors, revealing striking differences. In particular, granule proteins were significantly more abundant in the MS neutrophils compared to the healthy controls, with a particular overabundance of proteins in primary and secondary granules. In addition, members of the MAVS signalling pathway were differently regulated compared to healthy donor cells. Finally, we find that MS neutrophils do not suppress T cell activation equivalently to healthy neutrophils, and in particular are unable to suppress expression of CD161 on the T cells, indicative of a suppression of Th17 differentiation. We propose that neutrophil dysregulation in MS may contribute to dysfunctional T cell responses.