HLA-DR15 Molecules Jointly Shape an Autoreactive T Cell Repertoire in Multiple Sclerosis.

The HLA-DR15 haplotype is the strongest genetic risk factor for multiple sclerosis (MS), but our understanding of how it contributes to MS is limited. Because autoreactive CD4+ T cells and B cells as antigen-presenting cells are involved in MS pathogenesis, we characterized the immunopeptidomes of the two HLA-DR15 allomorphs DR2a and DR2b of human primary B cells and monocytes, thymus, and MS brain tissue. Self-peptides from HLA-DR molecules, particularly from DR2a and DR2b themselves, are abundant on B cells and thymic antigen-presenting cells. Furthermore, we identified autoreactive CD4+ T cell clones that can cross-react with HLA-DR-derived self-peptides (HLA-DR-SPs), peptides from MS-associated foreign agents (Epstein-Barr virus and Akkermansia muciniphila), and autoantigens presented by DR2a and DR2b. Thus, both HLA-DR15 allomorphs jointly shape an autoreactive T cell repertoire by serving as antigen-presenting structures and epitope sources and by presenting the same foreign peptides and autoantigens to autoreactive CD4+ T cells in MS.

Memory B Cells Activate Brain-Homing, Autoreactive CD4+ T Cells in Multiple Sclerosis.

Multiple sclerosis is an autoimmune disease that is caused by the interplay of genetic, particularly the HLA-DR15 haplotype, and environmental risk factors. How these etiologic factors contribute to generating an autoreactive CD4+ T cell repertoire is not clear. Here, we demonstrate that self-reactivity, defined as "autoproliferation" of peripheral Th1 cells, is elevated in patients carrying the HLA-DR15 haplotype. Autoproliferation is mediated by memory B cells in a HLA-DR-dependent manner. Depletion of B cells in vitro and therapeutically in vivo by anti-CD20 effectively reduces T cell autoproliferation. T cell receptor deep sequencing showed that in vitro autoproliferating T cells are enriched for brain-homing T cells. Using an unbiased epitope discovery approach, we identified RASGRP2 as target autoantigen that is expressed in the brain and B cells. These findings will be instrumental to address important questions regarding pathogenic B-T cell interactions in multiple sclerosis and possibly also to develop novel therapies.

Structural insights into human MHC-II association with invariant chain.

The loading of processed peptides on to major histocompatibility complex II (MHC-II) molecules for recognition by T cells is vital to cell-mediated adaptive immunity. As part of this process, MHC-II associates with the invariant chain (Ii) during biosynthesis in the endoplasmic reticulum to prevent premature peptide loading and to serve as a scaffold for subsequent proteolytic processing into MHC-II-CLIP. Cryo-electron microscopy structures of full-length Human Leukocyte Antigen-DR (HLA-DR) and HLA-DQ complexes associated with Ii, resolved at 3.0 to 3.1 Å, elucidate the trimeric assembly of the HLA/Ii complex and define atomic-level interactions between HLA, Ii transmembrane domains, loop domains, and class II-associated invariant chain peptides (CLIP). Together with previous structures of MHC-II peptide loading intermediates DO and DM, our findings complete the structural path governing class II antigen presentation.

Expression of HLA-DR by mesenchymal stromal cells in the platelet lysate era: an obsolete release criterion for MSCs?

BACKGROUND: According to the definition of the International Society for Cell and Gene Therapy (ISCT), mesenchymal stromal cells (MSCs) do not express HLA-DR. This phenotypic marker as a release criterion for clinical use was established at a time when MSCs were expanded in fetal bovine serum (FBS)-containing media. Replacement of FBS with platelet lysate (PLs) as a medium supplement induced a significantly higher fraction of MSCs to express MHC class II antigens. METHODS: As this raised concerns that such MSCs may play the role of antigen-presenting cells for T cells, in the current study, we studied major factors that may induce HLA-DR on MSCs by means of flow cytometry and real-time polymerase chain reaction. The immunomodulatory potential of MSCs was assessed by a mixed lymphocyte reaction. RESULTS: Our results demonstrated that a very low percentage of generated and expanded MSCs in FBS express HLA-DR (median: 1.1%, range: 0.3-22%) compared to MSCs generated and expanded in PLs (median: 28.4%, range: 3.3-73.7%). Analysis of the cytokine composition of ten PLs showed a significant positive correlation between the levels of IL-1ß, IL-4, IL-10, IL-17, bFGF and expression of HLA-DR, in contrast to no correlation with the age of MSC donors and HLA-DR (r = 0.21). Both MSCs expressing low and high levels of HLA-DR expressed class II transactivator (CIITA), a master gene coding for these molecules. Our results demonstrate for the first time that MSCs with constitutively high levels of HLA-DR also express moderate levels of indoleamine 2,3-dioxygenase (IDO). Treatment of MSCs with multiple doses of TGF-ß1 at passage 0 (P0) and passage 1 (P1) completely abrogated HLA-DR and IDO expression. In contrast, treatment of MSCs with a single dose of TGF-ß1 after P0 only partially reduced the expression of HLA-DR and CIITA. Remarkably, increased expression of HLA-DR on MSCs that constitutively express high levels of this antigen after overnight incubation with IFN-γ was rather unaffected by incubation with TGF-ß1. However, treatment of MSCs with TGF-ß1 for 24 h completely abrogated constitutive expression of IDO. CONCLUSIONS: Irrespective of HLA-DR expression at the population level, all MSC preparations significantly inhibited the proliferation of stimulated peripheral blood mononuclear cells, indicating that HLA-DR represents an obsolete release marker for the clinical use of MSCs.

The Association of Class I and II Human Leukocyte Antigen Serotypes With End-Stage Kidney Disease Due to Membranoproliferative Glomerulonephritis and Dense Deposit Disease.

RATIONALE & OBJECTIVE: Membranoproliferative glomerulonephritis (MPGN), encompassing several distinct diseases, is a rare but significant cause of kidney failure in the United States. The potential etiologies of MPGN are unclear, but prior studies have suggested dysregulation of the alternative complement pathway and, recently, autoimmunity as potential mechanisms driving MPGN pathogenesis. In this study, we examined HLA associations with end-stage kidney disease (ESKD) due to MPGN and dense deposit disease (DDD) in a large racially and ethnically diverse US-based cohort. STUDY DESIGN: Case-control study. SETTING & PARTICIPANTS: Using US Renal Data System (USRDS) and United Network for Organ Sharing (UNOS) data, we identified 3,424 patients with kidney failure due to MPGN and 263 due to DDD. We matched patients to kidney donor controls on designated race and ethnicity in a 1:15 ratio. EXPOSURE: 58 class I and II HLA serotypes. OUTCOME: Case-control status. ANALYTICAL APPROACH: For each disease cohort, univariable and multivariable logistic regression analyses were used to investigate associations between the disease and 58 HLA serotypes. In subgroup analyses, we investigated HLA associations in White and Black patients. We also studied antiglomerular basement membrane (anti-GBM) nephritis as a positive-control outcome. We applied a Bonferroni correction to account for multiple comparisons. RESULTS: Eighteen serotypes were significantly associated with the odds of having MPGN in univariable analyses, with DR17 having the strongest association (odds ratio [OR], 1.55 [95% CI, 1.44-1.68], P=4.33e-28). No significant associations were found between any HLA serotype and DDD. Designated race-specific analyses showed comparable findings. We recapitulated known HLA associations in anti-GBM nephritis. LIMITATIONS: Reliance on HLA serotypes (rather than genotype), lack of biopsy-confirmed diagnoses. CONCLUSIONS: HLA-DR17 is associated with ESKD due to MPGN in a racially and ethnically diverse cohort. The strength of association was similar in White and Black patients, suggesting a role in the pathogenesis of MPGN. No HLA associations were observed in patients with DDD. PLAIN-LANGUAGE SUMMARY: Prior studies have suggested dysregulation of the alternative complement pathway as a potential etiology of membranoproliferative glomerulonephritis (MPGN), but recent evidence from a British White population has implicated an autoimmune mechanism in MPGN pathogenesis. We investigated HLA associations between MPGN and dense deposit disease (DDD) in a large racially and ethnically diverse cohort of patients. We found that HLA-DR17 is associated with end-stage kidney disease (ESKD) due to MPGN in both White and Black patients. By contrast, no significant HLA associations with ESKD due to DDD were identified. These results suggest a role for autoimmunity in some cases of MPGN and highlight differences in the disease etiology of MPGN compared with DDD.

Differentiating idiopathic inflammatory myopathies by automated morphometric analysis of MHC-1, MHC-2 and ICAM-1 in muscle tissue.

AIMS: Diagnosis of idiopathic inflammatory myopathies (IIM) is based on morphological characteristics and the evaluation of disease-related proteins. However, although broadly applied, substantial bias is imposed by the respective methods, observers and individual staining approaches. We aimed to quantify the protein levels of major histocompatibility complex (MHC)-1, (MHC)-2 and intercellular adhesion molecule (ICAM)-1 using an automated morphometric method to mitigate bias. METHODS: Double immunofluorescence staining was performed on whole muscle sections to study differences in protein expression in myofibre and endomysial vessels. We analysed all IIM subtypes including dermatomyositis (DM), anti-synthetase syndrome (ASyS), inclusion body myositis (IBM), immune-mediated-necrotising myopathy (IMNM), dysferlinopathy (DYSF), SARS-CoV-2 infection and vaccination-associated myopathy. Biopsies with neurogenic atrophy (NA) and normal morphology served as controls. Bulk RNA-Sequencing (RNA-Seq) was performed on a subset of samples. RESULTS: Our study highlights the significance of MHC-1, MHC-2 and ICAM-1 in diagnosing IIM subtypes and reveals distinct immunological profiles. RNASeq confirmed the precision of our method and identified specific gene pathways in the disease subtypes. Notably, ASyS, DM and SARS-CoV-2-associated myopathy showed increased ICAM-1 expression in the endomysial capillaries, indicating ICAM-1-associated vascular activation in these conditions. In addition, ICAM-1 showed high discrimination between different subgroups with high sensitivity and specificity. CONCLUSIONS: Automated morphometric analysis provides precise quantitative data on immune-associated proteins that can be integrated into our pathophysiological understanding of IIM. Further, ICAM-1 holds diagnostic value for the detection of IIM pathology.

A large single-center cohort of bare lymphocyte syndrome: Immunological and genetic features in Turkey.

Major histocompatibility complex class II (MHC-II) deficiency or bare lymphocyte syndrome (BLS) is a rare, early-onset, autosomal recessive, and life-threatening inborn error of immunity. We aimed to assess the demographic, clinical, laboratory, follow-up, and treatment characteristics of patients with MHC-II deficiency, together with their survival. We retrospectively investigated 21 patients with MHC-II deficiency. Female/male ratio was 1.63. The median age at diagnosis was 16.3 months (5 months-9.7 years). Nineteen patients (90.5%) had parental consanguinity. Pulmonary diseases (pneumonia, chronic lung disease) (81%), diarrhoea (47.6%), and candidiasis (28.6%) were common. Four (19%) had autoimmunity, two developed septic arthritis, and three (14%) developed bronchiectasis in the follow-up. Three patients (14%) had CMV viraemia, one with bilateral CMV retinitis. Eight (38.1%) had lymphocytopenia, and four (19%) had neutropenia. Serum IgM, IgA, and IgG levels were low in 18 (85.7%), 15 (71.4%), and 11 (52.4%) patients, respectively. CD4+ lymphocytopenia, a reversed CD4+/CD8+ ratio, and absent/low HLA-DR expressions were detected in 93.3%, 86.7%, and 100% of the patients, respectively. Haematopoietic stem cell transplantation (HSCT) was performed on nine patients, and four died of septicaemia and ARDS after HSCT. The present median age of patients survived is 14 years (1-31 years). Genetic analysis was performed in 10 patients. RFX5 homozygous gene defect was found in three patients (P1, P4 and P8), and RFXANK (P2 and P14) and RFXAP (P18 and P19) heterozygous gene defects were found in each two patients, respectively. This large cohort showed that BLS patients have severe combined immunodeficiency (SCID)-like clinical findings. Flow cytometric MHC-II expression study is crucial for the diagnosis, differential diagnosis with SCID, early haematopoietic stem cell transplantation (HSCT), and post-HSCT follow-up. Genetic studies are required first for matched family donor evaluation before HSCT and then for genetic counselling.

Causal association between circulating blood cell traits and pulmonary embolism: a mendelian randomization study.

BACKGROUND: Pulmonary embolism (PE) is a life-threatening thromboembolic disease for which there is limited evidence for effective prevention and treatment. Our goal was to determine whether genetically predicted circulating blood cell traits could influence the incidence of PE. METHODS: Using single variable Mendelian randomization (SVMR) and multivariate Mendelian randomization (MVMR) analyses, we identified genetic associations between circulating blood cell counts and lymphocyte subsets and PE. GWAS blood cell characterization summary statistics were compiled from the Blood Cell Consortium. The lymphocyte subpopulation counts were extracted from summary GWAS statistics for samples from 3757 individuals that had been analyzed by flow cytometry. GWAS data related to PE were obtained from the FinnGen study. RESULTS: According to the SVMR and reverse MR, increased levels of circulating white blood cells (odds ratio [OR]: 0.88, 95% confidence interval [CI]: 0.81-0.95, p = 0.0079), lymphocytes (OR: 0.90, 95% CI: 0.84-0.97, p = 0.0115), and neutrophils (OR: 0.88, 95% CI: 0.81-0.96, p = 0.0108) were causally associated with PE susceptibility. MVMR analysis revealed that lower circulating lymphocyte counts (OR: 0.84, 95% CI: 0.75-0.94, p = 0.0139) were an independent predictor of PE. According to further MR results, this association may be primarily related to HLA-DR+ natural killer (NK) cells. CONCLUSIONS: Among European populations, there is a causal association between genetically predicted low circulating lymphocyte counts, particularly low HLA-DR+ NK cells, and an increased risk of PE. This finding supports observational studies that link peripheral blood cells to PE and provides recommendations for predicting and preventing this condition.

HLA-DR Expression in Natural Killer Cells Marks Distinct Functional States, Depending on Cell Differentiation Stage.

HLA-DR-positive NK cells, found in both healthy individuals and patients with different inflammatory diseases, are characterized as activated cells. However, data on their capacity for IFNγ production or cytotoxic response vary between studies. Thus, more precise investigation is needed of the mechanisms related to the induction of HLA-DR expression in NK cells, their associations with NK cell differentiation stage, and functional or metabolic state. In this work, HLA-DR-expressing NK cell subsets were investigated using transcriptomic analysis, metabolic activity assays, and analysis of intercellular signaling cascades. We demonstrated that HLA-DR+CD56bright NK cells were characterized by a proliferative phenotype, while HLA-DR+CD56dim NK cells exhibited features of adaptive cells and loss of inhibitory receptors with increased expression of MHC class II trans-activator CIITA. The activated state of HLA-DR-expressing NK cells was confirmed by higher levels of ATP and mitochondrial mass observed in this subset compared to HLA-DR- cells, both ex vivo and after stimulation in culture. We showed that HLA-DR expression in NK cells in vitro can be induced both through stimulation by exogenous IL-2 and IL-21, as well as through auto-stimulation by NK-cell-produced IFNγ. At the intracellular level, HLA-DR expression depended on the activation of STAT3- and ERK1/2-mediated pathways, with subsequent activation of isoform 3 of the transcription factor CIITA. The obtained results broaden the knowledge about HLA-DR-positive NK cell appearance, diversity, and functions, which might be useful in terms of understanding the role of this subset in innate immunity and assessing their possible implications in NK cell-based therapy.

Intermittent hypoxia treatments cause cellular priming in human microglia.

Obstructive sleep apnoea syndrome (OSAS) is a sleep-disordered breathing characterized by nocturnal collapses of the upper airway resulting in cycles of blood oxygen partial pressure oscillations, which lead to tissue and cell damage due to intermittent hypoxia (IH) episodes. Since OSAS-derived IH may lead to cognitive impairment through not fully cleared mechanisms, herein we developed a new in vitro model mimicking IH conditions to shed light on its molecular effects on microglial cells, with particular attention to the inflammatory response. The in vitro model was set-up and validated by measuring the hypoxic state, HIF-1α levels, oxidative stress by ROS production and mitochondrial activity by MTS assay. Then, the mRNA and protein levels of certain inflammatory markers (NF-κB and interleukin 6 (IL-6)) after different IH treatment protocols were investigated. The IH treatments followed by a normoxic period were not able to produce a high inflammatory state in human microglial cells. Nevertheless, microglia appeared to be in a state characterized by increased expression of NF-κB and markers related to a primed phenotype. The microglia exposed to IH cycles and stimulated with exogenous IL-1ß resulted in an exaggerated inflammatory response with increased NF-κB and IL-6 expression, suggesting a role for primed microglia in OSAS-driven neuroinflammation.

Immunoparalysis in critically ill children.

Immunoparalysis is associated with poorer outcomes in the paediatric intensive care unit (PICU) setting. We aimed to determine the group of patients with higher chances of immunoparalysis and correlate this status with increased risks of nosocomial infection and adverse clinical parameters. We conducted an exploratory study with prospective data collection in a university-affiliated tertiary medical, surgical, and cardiac PICU. Fifteen patients with multiple organ dysfunction syndrome were included over a period of 6 months. Monocyte's human leucocyte antigen (HLA)-DR expression and tumour necrosis factor (TNF)-α and interleukin (IL)-6 production were measured by flow-cytometry at three time points (T1 = 1-2 days; T2 = 3-5 days; T3 = 6-8 days). Using the paediatric logistic organ dysfunction-2 score to assess initial disease severity, we established the optimal cut-off values of the evaluated parameters to identify the subset of patients with a higher probability of immunoparalysis. A comparative analysis was performed between them. Sixty per cent were males; the median age was 4.1 years. Considering the presence of two criteria in T1 (classical monocytes mean fluorescence intensity [MFI] for HLA-DR ≤ 1758.5, area under the curve (AUC) = 0.775; and frequency of monocytes producing IL-6 ≤ 68.5%, AUC = 0.905) or in T3 (classical monocytes MFI of HLA-DR ≤ 2587.5, AUC = 0.675; and frequency of monocytes producing TNF-α ≤ 93.5%, AUC = 0.833), a variable to define immunoparalysis was obtained (100% sensitivity, 81.5% specificity). Forty per cent of patients were assigned to the immunoparalysis group. In this: a higher frequency of nosocomial infection (p = 0.011), vasoactive inotropic score (p = 0.014) and length of hospital stay (p = 0.036) was observed. In the subgroup with the diagnosis of sepsis/septic shock (n = 5), patients showed higher percentages of non-classical monocytes (p = 0.004). No mortality was recorded. A reduction in classical monocytes HLA-DR expression with lower frequencies of monocytes producing TNF-α and IL-6 during the first week of critical illness, appears to be a good marker of immunoparalysis; these findings relate to an increased risk of nosocomial infection and deleterious outcomes. The increased frequency of non-classical monocytes in patients with sepsis/septic shock is suggestive of a better prognosis.

A paired-kidney allocation study found superior survival with HLA-DR compatible kidney transplants in the Eurotransplant Senior Program.

The Eurotransplant Senior Program (ESP) has expedited the chance for elderly patients with kidney failure to receive a timely transplant. This current study evaluated survival parameters of kidneys donated after brain death with or without matching for HLA-DR antigens. This cohort study evaluated the period within ESP with paired allocation of 675 kidneys from donors 65 years and older to transplant candidates 65 years and older, the first kidney to 341 patients within the Eurotransplant Senior DR-compatible Program and 334 contralateral kidneys without (ESP) HLA-DR antigen matching. We used Kaplan-Meier estimates and competing risk analysis to assess all cause mortality and kidney graft failure, respectively. The log-rank test and Cox proportional hazards regression were used for comparisons. Within ESP, matching for HLA-DR antigens was associated with a significantly lower five-year risk of mortality (hazard ratio 0.71; 95% confidence interval 0.53-0.95) and significantly lower cause-specific hazards for kidney graft failure and return to dialysis at one year (0.55; 0.35-0.87) and five years (0.73; 0.53-0.99) post-transplant. Allocation based on HLA-DR matching resulted in longer cold ischemia (mean difference 1.00 hours; 95% confidence interval: 0.32-1.68) and kidney offers with a significantly shorter median dialysis vintage of 2.4 versus 4.1 yrs. in ESP without matching. Thus, our allocation based on HLA-DR matching improved five-year patient and kidney allograft survival. Hence, our paired allocation study suggests a superior outcome of HLA-DR matching in the context of old-for-old kidney transplantation.

PAD2 immunization induces ACPA in wild-type and HLA-DR4 humanized mice.

Rheumatoid arthritis (RA) is associated with HLA-DRB1 alleles expressing the "shared epitope." RA is usually preceded by the emergence of anti-citrullinated protein autoantibodies (ACPAs). ACPAs recognize citrulline residues on numerous proteins. Conversion of arginine into citrulline is performed by enzymes called peptidyl arginine deiminases (PADs). We have previously demonstrated that C3H mice immunized with PADs can produce ACPAs by a hapten-carrier mechanism. Here, we address the influence of HLA-DR alleles in this model in mice expressing RA-associated HLA-DRB1*04:01 (KO/KI*04:01), HLA-DRB1*04:04 (KO/KI*04:04), or non-RA-associated HLA-DRB1*04:02 (KO/KI*04:02) after murine PAD2 immunization. Immunization with mPAD2 triggers production of ACPAs in wild-type (WT) and HLA-DR4 C57BL/6 mice. Both I-Ab and HLA-DR are involved in the activation of mPAD2-specific T lymphocytes. Among HLA-DR4 mice, mice expressing RA-associated HLA-DRB1*04:01 are the best responders to mPAD2 and the best anti-citrullinated peptide antibody producers.

Bone marrow overexpression of SNAI1 is an early indicator of intrinsic drug resistance in patients with de novo acute myeloid leukemia.

BACKGROUND: The lack of effectiveness of acute myeloid leukemia (AML) treatment remains a major challenge and resembles a principal cause of AML-related mortality owing to chemotherapy resistance. SNAI1 has been proved to be a leading factor in drug resistance in many cancer types. However, its relation to chemoresistance in AML is not well understood. METHODS: In addition to standard lab work, the expression level of SNAI1 was determined in bone marrow samples of 109 adult and pediatric patients with de novo acute myeloid leukemia using RT-qPCR. The relation between SNAI1 and AML drug resistance and immunomodulatory genes was investigated using the STRING tool. RESULTS: The SNAI1 expression level was upregulated in AML patients in particular samples with promyelocytic leukemia subtype against control cases. In the treatment response, SNAI1 was significantly higher in resistant patients in comparison with the complete remission group. SNAI1 overexpression was associated with high initial blasts and total leukocyte counts, but with HLA class II histocompatibility antigen DR downregulation. STRING analysis showed that multiple drug resistance and immunomodulatory genes of AML induce SNAI upregulation and activation. Kaplan-Meier analysis indicated that there was no relation between SNAI1 expression level and patient survival status. CONCLUSION: We conclude that the SNAI1 expression level may be a predictor of intrinsic drug resistance incidence in AML patients.

HLA-DR+ mucosal-associated invariant T cells predict poor prognosis in patients with sepsis: A prospective observational study.

Mucosal-associated invariant T (MAIT) cells are important in antibacterial immune responses; however, during sepsis, they are few in number and exhibit highly activated phenotypes. The relationship between MAIT cells in peripheral blood and the prognosis of sepsis is not well understood. Thus, this study aimed to examine the levels and phenotypes of MAIT cells in early sepsis, evaluate their clinical relevance, and investigate their association with patient prognosis. This prospective observational study enrolled 72 septic patients defined according to the Sepsis 3.0 criteria and 21 healthy controls matched for age and sex. Their peripheral blood samples were used to assay the expression of immune activation (CD69 and HLA-DR) and immune checkpoint (PD-1 and PD-L1) markers on MAIT cells. The systemic inflammatory response syndrome, acute physiology and chronic health evaluation (APACHE) II, and sequential organ failure assessment scores were recorded. Subsequently, the association between MAIT cell characteristics and clinical indicators was assessed using Spearman's rank correlation analysis, and binary logistic regression analysis with a forward stepwise approach assessed independent risk factors for 28-day mortality. We noted a decrease in the percentage of MAIT cells in the patients' peripheral blood, which exhibited an activated phenotype. Besides, HLA-DR+ MAIT cell percentage and the APACHE II score were independently associated with the 28-day mortality and, in combination, were the best indicators of mortality. Thus, the percentage of HLA-DR+ MAIT cells in early sepsis serves as a novel prognostic biomarker for predicting mortality and improves the predictive capacity of the APACHE II score.

Kynurenine pathway alteration in acute pancreatitis and its role as a biomarker of infected necrosis.

INTRODUCTION: Infected pancreatic necrosis (IPN) is a major cause of mortality in acute pancreatitis (AP). Currently, no specific strategies are available to predict the development of IPN. Earlier we reported that persistent down-regulation of HLA-DR increases risk of developing IPN. Altered kynurenine pathway (KP) metabolites showed poor prognosis in sepsis. Here we evaluated the role of HLA-DR and KP in IPN. METHODS: Patients with ANP and healthy controls were enrolled. Demographic and clinical parameters were recorded. Circulating interleukin (IL)-8, 6, 1ß, 10, Tumor necrosis factor-α were quantified using flowcytometry. Plasma procalcitonin, endotoxin, and KP (tryptophan, kynurenine) concentrations were estimated using ELISA. qRT-PCR was conducted to evaluate mRNA expression of HLA-DR, IL-10, Toll like receptor-4 (TLR-4), and kynurenine-3-monooxygenase (KMO) genes on peripheral blood mononuclear cells. Plasma metabolites were quantified using gas chromatography mass spectrometry (GC-MS/MS). Standard statistical methods were used to compare study groups. Metaboanalyst was used to analyse/visualize the metabolomics data. RESULTS: We recruited 56 patients in Cohort-1 (IPN:26,Non-IPN:30), 78 in Cohort-2 (IPN:57,Non-IPN:21), 26 healthy controls. Increased cytokines, endotoxin, and procalcitonin were observed in patients with IPN compared to Non-IPN. HLA-DR and KMO gene expressions were significantly down-regulated in IPN groups, showed positive correlation with one another but negatively correlated with IL-6 and endotoxin concentrations. Increased IDO and decreased plasma tryptophan were observed in IPN patients. Metabolome analysis showed significant reduction in several essential amino acids including tryptophan in IPN patients. Tryptophan, at a concentration of 9 mg/ml showed an AUC of 91.9 (95%CI 86.5-97.4) in discriminating IPN. CONCLUSION: HLA-DR downregulation and KP alteration are related to IPN. The KP metabolite plasma tryptophan can act as a potential biomarker for IPN.

Effects of carrimycin on biomarkers of inflammation and immune function in tumor patients with sepsis: A multicenter double-blind randomized controlled trial.

Carrimycin is a potential immune-regulating agent for sepsis in patients with tumors. In this study, we investigated its effects on inflammation and immune function in tumor patients with sepsis. In total, 120 participants were randomized to receive either carrimycin treatment (400 mg/day) (n = 62) or placebo (n = 58) for 7 days. The primary outcomes were immune-related indicators. Subsequently, patients were stratified into two subgroups (CD4 < 38.25% and CD8 < 25.195%). Ninety-nine participants were analyzed: 47 and 52 in the carrimycin and placebo groups, respectively. HLA-DR levels were rapidly increased in the carrimycin group; however, the placebo group initially experienced a decline in HLA-DR level at 1 day after administration. In the subgroup with CD4 < 38.25%, the carrimycin group exhibited significantly higher HLA-DR levels than the placebo group (2.270, P = 0.023) 1 day after administration and the degree of increase in HLA-DR in the carrimycin group was higher than that in the placebo group (2.057, P = 0.040). In the CD8 < 25.195% subgroup, the carrimycin group demonstrated significantly higher levels of CD8+ T cells than the placebo group at 3 (2.300,P = 0.027) and 5 (2.106, P = 0.035) days after administration. Carrimycin intervention led to significant reductions in the SOFA, APACHE II, PCT, and CRP levels. No adverse events were observed. In tumor patients with sepsis, particularly in those experiencing immunological suppression, carrimycin effectively regulates immune responses by increasing HLA-DR and CD8+ T cell levels and plays an anti-infective role, reducing disease severity. (Chictr.org.cn, ID Number: ChiCTR2000032339).

Prospective flow cytometry analysis of leucocyte subsets in critically ill patients who develop sepsis: a pilot study.

PURPOSE: Sepsis in critically ill patients with injury bears a high morbidity and mortality. Extensive phenotypic monitoring of leucocyte subsets in critically ill patients at ICU admission and during sepsis development is still scarce. The main objective of this study was to identify early changes in leukocyte phenotype which would correlate with later development of sepsis. METHODS: Patients who were admitted in a tertiary ICU for organ support after severe injury (elective cardiac surgery, trauma, necessity of prolonged ventilation or stroke) were sampled on admission (T1) and 48-72 h later (T2) for phenotyping of leukocyte subsets by flow cytometry and cytokines measurements. Those who developed secondary sepsis or septic shock were sampled again on the day of sepsis diagnosis (Tx). RESULTS: Ninety-nine patients were included in the final analysis. Nineteen (19.2%) patients developed secondary sepsis or septic shock. They presented significantly higher absolute monocyte counts and CRP at T1 compared to non-septic patients (1030/µl versus 550/µl, p = 0.013 and 5.1 mg/ml versus 2.5 mg/ml, p = 0.046, respectively). They also presented elevated levels of monocytes with low expression of L-selectin (CD62Lneg monocytes) (OR[95%CI] 4.5 (1.4-14.5), p = 0.01) and higher SOFA score (p < 0.0001) at T1 and low mHLA-DR at T2 (OR[95%CI] 0.003 (0.00-0.17), p = 0.049). Stepwise logistic regression analysis showed that both monocyte markers and high SOFA score (> 8) were independently associated with nosocomial sepsis occurrence. No other leucocyte count or surface marker nor any cytokine measurement correlated with sepsis occurrence. CONCLUSION: Monocyte counts and change of phenotype are associated with secondary sepsis occurrence in critically ill patients with injury.

Immune responses of patients on maintenance hemodialysis after infection by SARS-CoV-2: a prospective observational cohort study.

BACKGROUND: Immune dysregulation in patients with acute COVID-19 under chronic hemodialysis (CHD) is fully not elucidated. The changes of mononuclear counts and mediators before and after HD and associations with final outcome were studied. METHOD: In this prospective study, hospitalized patients with moderate-to-severe COVID-19 under CHD and matched comparators under HD were analyzed for their absolute counts of lymphoid cells and circulating inflammatory mediators. Blood samples were collected before start and at the end of the first HD session; dialysate samples were also collected. RESULT: Fifty-nine patients with acute COVID-19 under CHD and 20 uninfected comparators under CHD were enrolled. Circulating concentrations of tumor necrosis factor-alpha (TNFα), interleukin (IL)-10, interferon-γ and platelet-derived growth factor-A were increased in patients. Concentrations of mediators did not differ before and after HD. Significant decreases of CD4-lymphocytes and CD19-lymphocytes were found in patients. The decrease of the expression of HLA-DR on CD14-monocytes was associated with unfavorable outcome (defined as WHO-CPS 6 or more by day 28); increased counts of CD19-lymphocytes were associated with better outcomes. CONCLUSION: Patients under CHD develop an inflammatory reaction to SARS-CoV-2 characterized by increase of inflammatory mediators, decrease of circulating T-lymphocytes and decrease of the expression of HLA-DR on CD14-monocytes.

Lactoferrin and its digestive peptides induce interferon-α production and activate plasmacytoid dendritic cells ex vivo.

Plasmacytoid dendritic cells (pDCs) recognise viral single-stranded RNA (ssRNA) or CpG DNA via Toll-like receptor (TLR)-7 and TLR9, and produce interferon (IFN)-α. Activated pDCs upregulate human leukocyte antigen (HLA)-DR and CD86 expression levels. Ingestion of bovine lactoferrin (LF) activates pDCs, but little is known about its effects. In this study, the effects of LF and its pepsin hydrolysate (LFH) on the production of IFN-α from peripheral blood mononuclear cells (PBMCs) and pDCs were examined. PBMCs were prepared from peripheral blood of healthy adults and incubated with LF, LFH, or lactoferricin (LFcin) in the absence or presence of ssRNA derived from human immunodeficiency virus. The concentration of IFN-α in the supernatant and the expression levels of IFN-α, HLA-DR, and CD86 in pDCs were quantified by enzyme-linked immunosorbent assay and flow cytometry. In the absence of ssRNA, the concentration of IFN-α was negligible and LF had no effect on it. In the presence of ssRNA, IFN-α was detected at a certain level, and LF and LFH significantly increased its concentration. The increase caused by LFH and LFcin were comparable. In addition, LF significantly upregulated the expression levels of IFN-α, HLA-DR, and CD86 in pDCs. LF and its digestive peptides induced IFN-α production and activated pDCs in the presence of ssRNA, suggesting that LF modulates the immune system by promoting pDC activation upon viral recognition.