Clinical Immunology

Systemic Lupus Erythematous (SLE) is a chronic autoimmune disorder, broadly characterized by systemic inflammation along with heterogeneous clinical manifestations, severe morbidity, moribund organ failure and eventual mortality. In our study, SLE patients displayed higher percentage of activated, inflamed and hyper polarized CD8+ T cells, dysregulated CD8+ T cell differentiation, significantly elevated serum inflammatory cytokines, higher accumulation of cellular ROS when compared to healthy controls. Importantly, these hyper inflammatory/hyper polarized CD8+ T cells responded better to an anti-oxidant than to an oxidant. Terminally differentiated Tc1 cells also showed plasticity upon Oxidant/antioxidant treatment but was in contrast to the SLE CD8+ T cell response. Our studies suggest that the differential phenotype and redox response of SLE CD8+ T cells and Tc1 cells could be attributed to their cytokine environs during their respective differentiation and eventual activation environs. Polarisation of Tc1 cells with IL-21 drove hyper cytoxicity without hyper polarisation suggesting that SLE inflammatory environment could drive the extreme aberrancy in SLE CD8+ T cell.

Initial symptoms of COVID-19 infection depend on viral replication, while hyperinflammation is a hallmark of critical illness and may drive severe pneumonia and death. Among the mechanisms potentially involved in the hyperinflammatory state, we focused on the unfolded protein response, because the IRE1-XBP1 branch can be activated as result of the endoplasmic reticulum stress produced by the overwhelming synthesis of viral components and synergizes with Toll-like receptor signaling to induce cytokine expression. Viral RNA may trigger the IRE1-XBP1 branch via TLR7/8 activation and like TLR2 and TLR4 may underpin cytokine expression trough XBP1 splicing (sXBP1). The expression of IL1B, IL6, and TNF mRNA in bronchoalveolar aspirates (BAAs) were higher in COVID-19 patients under mechanical ventilation and intubation who showed sXBP1. The scrutiny of monocytic/macrophagic markers during active infection showed a reduction of those involved in antigen presentation and survival, as well as the IFN stimulated gene MX1. These changes reverted after infection tests turned negative. In contrast, the expression of the mRNA of the serine protease TMPRSS2 involved in S protein priming showed a high expression during active infection. TLR8 mRNA showed an overwhelming expression as compared to TLR7 mRNA, which suggests the presence of monocyte-derived dendritic cells (MDDCs). In vitro experiments in MDDCs activated with ssRNA40, a positive-sense, single-stranded RNA (+ssRNA) like SARS-CoV-2 RNA, induced sXBP1 and the expression of IL-1{beta}, IL-6, and TNF at mRNA and protein levels. These responses were blunted by the IRE1 ribonuclease inhibitor MKC8866. Given the analogies between the results observed in BAAs and the effects induced by +ssRNA in MDDCs, IRE1 ribonuclease inhibition might be a druggable target in severe COVID-19 disease. O_FIG O_LINKSMALLFIG WIDTH=180 HEIGHT=200 SRC="FIGDIR/small/22269752v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@13b04b3org.highwire.dtl.DTLVardef@1b1af7corg.highwire.dtl.DTLVardef@780104org.highwire.dtl.DTLVardef@8ad0ba_HPS_FORMAT_FIGEXP M_FIG C_FIG Author summaryCOVID-19 pandemics put an unprecedented pressure on health systems. The need of new therapies urged research on the mechanisms triggered by the interaction of SARS-CoV-2 virus with host cells and the ensuing pathophysiology driving pneumonia and multiorgan failure. Hyperinflammation soon appeared as a mechanism involved in mortality that could even proceed after viral infection comes to an end. Hyperinflammation is supported by an inappropriate production of cytokines, and this explains the use of the term cytokine storm to refer to this phase of the disease. Given that insight into the molecular mechanisms driving cytokine storm should focus on the interaction of viral components with immune cells, experiments addressing the effect of viral components on its cognate receptors were carried out. It was observed that viral RNA induces a cytokine pattern like the one observed in bronchoalveolar aspirates of COVID-19 patients with critical disease. Overall, the study revealed that both cell organelle overload and receptors involved in the recognition of viral RNA may team up to induce proinflammatory cytokines. This mechanism can be exploited to develop new treatments for COVID-19 disease.

Long-COVID (LC) is a serious clinical condition characterised by debilitating fatigue together with a wide array of symptoms that significantly reduce the quality of life of patients. Currently no holistic or even symptom specific treatment options are available, likely due to both a lack of insight into the disease processes that drive LC symptoms and an extreme heterogeneity in patients profiles. We characterised patients and post infection controls, with respect to their immunological profiles with a non-exhaustive panel of biomarkers rationalised based on their potential role in driving symptoms. We observed that the patients symptoms could be grouped into 4 clusters suggesting possible stratification. Systemic inflammation persisted and did not normalize over time in LC. This was not related to persistent SARS-CoV-2 infection, as the presence of circulating N-protein was detected similarly in both patients and controls. No obvious deviation in B-cells and monocytes profiles were observed with minor changes for NK-cells (CD62L+/CD16+/HLA-DR+). Major changes affected CD4+T-cells (and to a lesser extent CD8+T-cells) with respect to exhaustion (PD1+/LAG3+/CD44+), regulation (Treg) and differentiation (naive/memory-CD62L+). Several candidate biomarkers (cytokines, microRNAs, phosphate metabolism) were present more frequently in LC at high levels and provided information on underlying disease processes. While frequencies of candidate autoantibody+ participants were not different, levels of some antibodies were higher in LC. Yet none of these candidates stood out as a universal biomarker for LC, with the exception of CRP (73% cases), and loss of Treg (50%). However, we confirmed that several overlapping underlying aetiologies may be involved in this complex disease. Specific groups of biomarkers also associated with the 4 cluster of patients. Although to be taken with caution due to small numbers, 3 biomarkers discriminated controls from patients (Treg/CD4+PD1+/CD4+CD161+), others were associated with symptoms recovery (low IL10/IL12/IL4 and high miR766) or deterioration (high CD4+CD38+/ CD8+naiveCD62L+/low IL2) over 12 months. This study provides rational for developing targeted therapeutic strategies as well as biomarkers to stratify LC patients most likely to respond.

BackgroundThe polymerized type I collagen (PTIC) is a {gamma}-irradiated mixture of pepsinized porcine type I collagen and polyvinylpyrrolidone (PVP). It has immunomodulatory properties. However, the receptor and signaling pathway through which it exerts its therapeutic effects has not yet been identified. AimTo evaluate LAIR-1 as a potential receptor for PTIC and the signaling pathway evoked by ligand-receptor binding. MethodsLAIR-1 binding assay was performed by incubating various concentrations of recombinant human LAIR-1 with native type I collagen or PTIC. Macrophages M1- derived from THP-1 cells were cultured with 2-10% PTIC for 24 h. Cell lysates from THP- 1, monocytes-like cells (MLCs), M1, M1+IFN-{gamma}, M1+LPS, and 2 or 10% PTIC treated M1 were analyzed by western blot for the transcription factors NF-{kappa}B (p65), p38, STAT-1, and pSTAT-1. Cytokines, Th1 cells, and M1/M2 macrophages were analyzed by luminometry and flow cytometry from blood samples of symptomatic COVID-19 outpatients on treatment with intramuscular administration of PTIC. ResultsPTIC binds LAIR-1 with a similar affinity to native collagen. This binding decreases STAT-1 signaling IFN-{gamma}-induced and IL-1{beta} expression in M1 macrophages by down-regulating STAT-1 phosphorylation. Moreover, intramuscular PTIC treatment of symptomatic COVID-19 outpatients decreased at statistically significant levels the percentage of M1 macrophages and cytokines (IP-10, MIF, eotaxin, IL-8, IL-1RA, and M- CSF) associated with STAT-1 transcription factor and increased M2 macrophages and Th1 cells. The downregulation of inflammatory mediators was related to better oxygen saturation and decreased dyspnea, chest pain, cough, and chronic fatigue syndrome in the acute phase of infection and the long term. ConclusionPTIC is an agonist of LAIR-1 and down-regulates STAT-1 phosphorylation. PTIC could be relevant for treating STAT-1-mediated inflammatory diseases, including COVID-19 and long COVID

Many COVID-19 patients demonstrate lethal respiratory complications caused by cytokine release syndrome (CRS). Multiple cytokines have been implicated in CRS, but TNFSF14 (LIGHT) has not been previously measured in this setting. In this study, we observed significantly elevated serum LIGHT levels in hospitalized COVID-19 patients as compared to healthy age and gender matched control patients. The assay detected bioavailable LIGHT unbound to the inhibitor Decoy receptor-3 (DcR3). Bioavailable LIGHT levels were elevated in patients both on and off ventilatory support, with a trend toward higher levels in patients requiring mechanical ventilation. In hospitalized patients over the age of 60, who exhibited a mortality rate of 82%, LIGHT levels were significantly higher (p=0.0209) in those who died compared to survivors. As previously reported, interleukin 6 (IL-6) levels were also elevated in these patients with significantly (p=0.0076) higher levels observed in patients who died vs. survivors, paralleling the LIGHT levels. Although attempts to block IL-6 binding to its receptor have shown limited effect in COVID-19 CRS, neutralization of LIGHT may prove to be more effective owing to its more central role in regulating antiviral immune responses.

Hypertension, vascular inflammation and renal inflammation are characteristic of systemic lupus erythematosus (SLE), a multisystem autoimmune disease that is complex and poorly understood. Oxidation products of arachidonic and other fatty acids, termed isolevuglandins (isoLG) lead to formation of post-translational protein modifications that are immunogenic. We demonstrate isoLG enrichment in dendritic cells (DCs), B cells, and plasma cells from juvenile female B6.SLE123 mice. In adult B6.SLE123 and NZBWF1 mice, isoLG adducts are enriched in plasma cells and splenic DCs compared to C57Bl/6 and NZW mice respectively. Treatment with the isoLG-scavenger 2-hydroxybenzylamine (2-HOBA) reduced blood pressure, improved renal function, and attenuated renal injury. Moreover, 2-HOBA reduced bone marrow plasma cells, total IgG levels, and anti-dsDNA antibody titers. We also demonstrate that mice with SLE generate specific IgG antibodies against isoLG adducted protein, confirming the immunogenicity of isoLG adducts. Finally, we found that isoLG adducted peptides are markedly enriched in monocytes from patients with SLE which was accompanied by an increase in superoxide production. These findings support a role of isoLG adducts in the genesis and maintenance of systemic autoimmunity and its associated hypertension in SLE. Scavenging of isoLGs promises to be a novel therapy for this disease.

BackgroundMyocarditis has emerged as a rare but lethal Immune checkpoint inhibitor (ICI)-associated toxicity. However, the exact mechanism for ICI related myocarditis remains underexplored; and the specific therapeutic targets is still lacking. In this study, we used scRNA-seq to characterize the transcriptomic profiles of single cells from the peripheral blood mononuclear cell (PBMC) of ICI related myocarditis during fulminant myocarditis and disease recovery. MethodsPBMC samples were taken from the patient during fulminant ICI related myocarditis and after disease remission. Cells were isolated from blood samples by density gradient centrifugation over Ficoll-Paque. Single-cell RNA sequencing with 10X genomics was performed. Subpopulation determination, functional analysis, single-cell trajectory and cell-cell interaction analysis were carried out afterwards. ResultsWe presented the altered landscape of immune cells and differential genes in ICI related myocarditis during the disease activity and remission using scRNA-seq. Substantial immune cell composition and intercellular communication were found to be altered. Monocyte, NK cell as well as B cell subpopulations contributed to the regulation of innate immunity and inflammation in ICI related myocarditis. T cell subpopulations highly expressed genes associated with PD-1 inhibitor resistance and hyper-progressor. At last, the intercellular communication in ICI related myocarditis was significantly dysregulated. ConclusionBy identifying altered pathways and highlighting a catalog of marker genes, this study has revealed the diversity of cellular populations in ICI related myocarditis, marked by their distinct transcriptional profiles and biological functions. Our investigation would shed light on the pathophysiological mechanism and potential therapeutic targets of ICI related myocarditis in continuous exploration.

ObjectiveThe aim of this study was to investigate relevance between type of autoantibody and gene expression profile in skin lesion of systemic sclerosis (SSc), and identify specifically dysregulated pathways. MethodsSixty-one patients with SSc from the Genetics versus Environment in Scleroderma Outcome Study cohort and thirty-six healthy controls (HC) are included. Differentially expressed genes (DEGs) were extracted and functional enrichment and pathways analysis were conducted. ResultsCompared with HC, lists consisting of 2, 71, 10, 144 and 78 DEGs were created for patients without specific autoantibody, anti-centromere (ACA), anti-U1 RNP (RNP), anti-RNA polymerase III (RNAP) and anti-topoisomerase I (ATA) antibody, respectively. While part of enriched pathways overlapped, distinct pathways were identified except those without specific autoantibody: keratinocyte differentiation in ACA, NF-kB signaling and cellular response to transforming growth factor beta stimulus in RNAP, interferon alpha/beta signaling of RNP and cellular response to stress in ATA. ConclusionPathogenic pathways were identified according to type of autoantibodies by leveraging gene expression data of patients and controls from multi-center cohort. The current study will promote to explore new therapeutic target for SSc. Key messageDistinct pathways are associated with type of autoantibody in skin lesion of systemic sclerosis.

The heterogeneous disease course of COVID-19 is unpredictable, ranging from mild self-limiting symptoms to cytokine storms, acute respiratory distress syndrome (ARDS), multi-organ failure and death. Identification of high-risk cases will enable appropriate intervention and escalation. This study investigates the routine laboratory tests and cytokines implicated in COVID-19 for their potential application as biomarkers of disease severity, respiratory failure and need of higher-level care. From analysis of 203 samples, CRP, IL-6, IL-10 and LDH were most strongly correlated with the WHO ordinal scale of illness severity, the fraction of inspired oxygen delivery, radiological evidence of ARDS and level of respiratory support (p[≤]0.001). IL-6 levels of [≥]3.27pg/ml provide a sensitivity of 0.87 and specificity of 0.64 for a requirement of ventilation, and a CRP of [≥]37mg/L of 0.91 and 0.66. Reliable stratification of high-risk cases has significant implications on patient triage, resource management and potentially the initiation of novel therapies in severe patients.

ObjectiveTo investigate the roles of chemokines in activating the NF-{kappa}B signaling pathway in retinal pigment epithelium (RPE) and photoreceptor cells, and their contribution to the pathogenesis of age-related macular degeneration (AMD). BackgroundAMD is a leading cause of vision loss in older adults, driven by chronic inflammation and oxidative stress. The NF-{kappa}B transcription factor plays a key role in regulating these processes, with various chemokines, such as CCL2 and CX3CL1, influencing NF-{kappa}B activation. Despite advances in treatment, a deeper understanding of how chemokines affect NF-{kappa}B activation in RPE and photoreceptor cells remains critical for developing effective therapies. This study seeks to address this gap and improve AMD management. MethodsA comprehensive search of databases, including PubMed, MEDLINE, and Google Scholar, was conducted to identify relevant studies on the roles of chemokines in activating NF-{kappa}B signaling in RPE and photoreceptor cells. The search covered chemokines such as CCL2 (MCP-1), CX3CL1 (Fractalkine), CCL3 (MIP-1), CCL5 (RANTES), CXCL8 (IL-8), CXCL10 (IP-10), CXCL1 (GRO-), CXCL12 (SDF-1), CCL11 (Eotaxin), CXCL16, CXCL9 (MIG), and CXCL11 (I-TAC). Studies were systematically reviewed following PRISMA guidelines to assess the involvement of these chemokines in NF-{kappa}B activation. ResultsThe analysis revealed that chemokines, including CCL2, CX3CL1, CCL3, and CCL5, significantly activated NF-{kappa}B in RPE and photoreceptor cells, leading to increased inflammation and apoptosis through enhanced cytokine production and reactive oxygen species (ROS) generation. Additionally, CXCL8, CXCL10, CXCL1, and CXCL12 triggered NF-{kappa}B activation, contributing to oxidative stress and extracellular matrix (ECM) remodeling, which disrupts retinal structure and function. Other chemokines, such as CCL11, CXCL16, CXCL9, and CXCL11, sustained chronic inflammation and modulated matrix metalloproteinases (MMPs), further implicating them in AMD progression. ConclusionChemokines, including CCL2, CX3CL1, CCL3, CCL5, CXCL8, CXCL10, CXCL1, CXCL12, CCL11, CXCL16, CXCL9, and CXCL11, activate the NF-{kappa}B pathway in RPE and photoreceptor cells, driving chronic inflammation, oxidative stress, and ECM remodeling in AMD. These findings highlight potential therapeutic targets to mitigate disease progression.

Multisystem Inflammatory Syndrome in Children associated with COVID-19 (MIS-C) is a late complication of pediatric COVID-19, which follows weeks after original SARS-CoV-2 infection, regardless of its severity. It is characterized by hyperinflammation, neutrophilia, lymphopenia and activation of T cells with elevated IFN-{gamma}. Observing production of autoantibodies and parallels with systemic autoimmune disorders, such as systemic lupus erythematodes (SLE), we explored B cell phenotype and serum levels of type I, II and III interferons, as well as the cytokines BAFF and APRIL in a cohort of MIS-C patients and healthy children after COVID-19. We documented a significant elevation of IFN-{gamma}, but not IFN- and IFN-{lambda} in MIS-C patients. BAFF was elevated in MIS-C patient sera and accompanied by decreased BAFFR expression on all B cell subtypes. The proportion of plasmablasts was significantly lower in patients compared to healthy post-COVID children. We noted the presence of ENA Ro60 autoantibodies in 4/35 tested MIS-C patients. Our work shows the involvement of humoral immunity in MIS-C and hints at parallels with the pathophysiology of SLE, with autoreactive B cells driven towards autoantibody production by elevated BAFF. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/22275245v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@166327dorg.highwire.dtl.DTLVardef@7cde7forg.highwire.dtl.DTLVardef@1f3a3b2org.highwire.dtl.DTLVardef@803175_HPS_FORMAT_FIGEXP M_FIG C_FIG Summary sentenceElevated serum BAFF in children with MIS-C supports the state of polyclonal B cell activation and autoimmune phenomena characterizing this disease.

ObjectiveTo investigate the role of cytokine-induced NF-{kappa}B activation in retinal pigment epithelium (RPE) and photoreceptor cells, elucidating its contribution to the pathogenesis of Age-related Macular Degeneration (AMD) and identifying potential therapeutic targets. BackgroundAMD is a leading cause of vision loss in older adults, driven by inflammation, oxidative stress, and immune dysregulation, particularly in RPE and photoreceptor cells. The NF-{kappa}B signaling pathway, activated by cytokines such as TNF-, IL-6, and IL-1{beta}, regulates these pathological processes. Understanding cytokine-induced NF-{kappa}B activation may provide insight into AMD progression and facilitate the development of novel therapeutic strategies. MethodsA systematic review of literature from databases including PubMed, MEDLINE, and Google Scholar was conducted to evaluate the involvement of TNF-, IL-6, IL-1{beta}, IL-8, IFN-{gamma}, IL-17, IL-12, IL-18, IL-33, and IL-25 in activating NF-{kappa}B in RPE and photoreceptor cells, contributing to AMD pathogenesis. The search was performed with no date restrictions and followed PRISMA guidelines. Eligible studies were selected based on predefined criteria assessing NF-{kappa}B activation mechanisms and its effects on inflammation, oxidative stress, and retinal degeneration. ResultsThe investigation revealed that cytokines TNF-, IL-6, IL-1{beta}, IL-8, IFN-{gamma}, IL-17, IL-12, IL-18, IL-33, and IL-25 activate the NF-{kappa}B signaling pathway in retinal pigment epithelium (RPE) and photoreceptor cells. This activation triggers the transcription of genes involved in inflammation, oxidative stress, and immune responses. Chronic NF-{kappa}B activation leads to persistent inflammation, increased oxidative stress, and immune cell recruitment, contributing to retinal cell dysfunction and degeneration. Additionally, NF-{kappa}B-driven upregulation of angiogenic factors such as VEGF promotes neovascularization in wet AMD. These findings highlight the central role of NF-{kappa}B in AMD pathogenesis and suggest that targeting this pathway could mitigate inflammatory and oxidative damage, offering potential therapeutic benefits for AMD patients. ConclusionCytokine-induced NF-{kappa}B activation plays a central role in AMD pathogenesis by promoting chronic inflammation, oxidative stress, and angiogenesis in retinal cells. Targeting NF-{kappa}B could present a therapeutic strategy to reduce inflammatory and oxidative damage, preserving retinal function and preventing vision loss in AMD. Further research is required to develop effective NF-{kappa}B-targeted interventions.

The Fc{gamma} receptors (Fc{gamma}Rs) act as modulators of the immune system and have previously been shown to play a role in immune disorders such as systemic lupus erythematosus and immune thrombocytopenic purpura. Thus far, their role in primary immunodeficiencies (PID), including common variable immunodeficiency disorders (CVID), has not been studied. In this paper we explored whether there is an association between the following single nucleotide polymorphisms (SNPs) and CVID: FCGR2A H131R (rs1801274), FCGR2B I232T (rs1050501), and FCGR3A F158V (rs396991). We compared the genotypes of a cohort of 83 patients with PID, including 56 with CVID, against controls. We found a significant difference between our mixed PID cohort and controls at the FCGR2A H131R SNP (X2 =7.884, p=0.019). There was not a significant difference at either of the other SNPs studied. Further, we examined the effect of FCGR SNPs on the incidence of the most common CVID complications within our cohort: anaemias, organ-specific autoimmunity, bronchiectasis, splenomegaly, granulomata, and cytopenias. We found no significant association between SNPs and the development of these complications. In summary, we have shown that there is a link between the FCGR2A H131R SNP and the development of a PID.

Background and AimAn essential issue for Kawasaki Disease (KD) is the development of coronary artery disease. We decided to investigate (VEGF) subtype gene expression in KD due to the proangiogenic nature of Vasoactive Endothelial Growth Factor A (VEGF). VEGF-A is a known angiogenic molecule with pro-inflammatory effects, whereas the role of VEGFB has been less defined. MethodKD Microarray and RNA-seq datasets were selected using a comprehensive search strategy of the NCBI GEO Dataset, which resulted in eight studies from whole blood. This included three extensive studies in KD (KD1-KD3). Further, one study dataset from coronary artery tissue, the Coronary Artery Dataset (CAD), was also included to appreciate end-stage KD. ResultsIn CAD, cases of KD versus controls, VEGF-B was up-regulated (p = 4.932e-02). KD1, KD Acute versus convalescent samples, VEGF-A is up-regulated (p=1.258e-07) and VEGF-B was down-regulated (p=1.42e-28). Similar up regulation of VEGF-A and down regulation of VEGF-B was seen in KD2 (p=1.140e-04; p=1.746e-02) and KD3 (p=1.140e-04; p=1.746e-02), both are KD Versus Controls. VEGF-A up-regulated (p=1.140e-04), VEGF-B down-regulated (p=1.746e-02).KD3, KD versus Control; VEGF-A up-regulated (p=1.140e-04), VEGF-B down regulated (p=1.746e-02). ConclusionsIn acute KD VEGF-A up-regulation, with VEGFB being down-regulated, the reverse being true of the convalescent situation. This suggests a temporal inverse relationship between VEGF-A and VEGF-B may have biomarker implications. Moreover, a dual therapeutic strategy, enhancing VEGFB while minimizing VEGFA effects, could be a possible advancement over current KD related-therapies. Further work defining the relationship of VEGF-A to VEGF-B in KD-related angiogenesis is suggested.

Multisystem inflammatory syndrome in children (MIS-C or PIMS) is a rare but serious complication after an infection with SARS-CoV-2. A possible involvement of pathogenetically relevant autoantibodies has been discussed. Recently neutralizing autoantibodies against anti-inflammatory receptor antagonists progranulin (PGRN) and IL-1-receptor antagonist (IL-1-Ra) were discovered in adult patients with critical COVID-19. Plasma of an index case with severe PIMS/MIS-C was analyzed for autoantibodies against IL-1-Ra and PGRN. The study was extended by a case series of 12 additional patients. In addition to ELISA for of antibodies, IL-1-Ra plasma levels were determined and IL-1-Ra was analyzed by Western-blot and isoelectric focusing. Functional activity of the autoantibodies was examined in vitro with IL-1{beta} reporter assays. Antibodies against IL-1-Ra could be detected in 10 of 13 (76.9%) patients with PIMS/MIS-C, but not in controls. In contrast to critical COVID-19 in adults, no IL-1-Ra antibodies of the IgM class were detected in PIMS/MIS-C. IL-1-Ra-antibodies exclusively belonged to IgG1. No antibodies directed against PGRN were detected. Western blots and ELISA showed a concomitant reduction of free IL-1-Ra plasma levels in the presence of IL-1-Ra-antibodies. The antibodies inhibited IL-1-Ra function in IL-1{beta} reporter cell assays. Notably, an additional, hyperphosphorylated, transiently occurring atypical isoform of IL-1-Ra was observed in all IL-1-Ra autoantibody-positive patients. To conclude, IL-1-Ra autoantibodies were observed in high frequency in children with PIMS/MIS-C. They may represent a diagnostic and pathophysiologically relevant marker for PIMS/MIS-C. Their generation is likely to be triggered by an atypical, hyperphosphorylated isoform of IL-1-Ra.

Infection caused by SARS-CoV-2 can result in severe respiratory complications and death. Patients with a compromised immune system are expected to be more susceptible to a severe disease course. In this report we suggest that patients with systemic lupus erythematous might be especially prone to severe COVID-19 independent of their immunosuppressed state from lupus treatment. Specially, we provide evidence in lupus to suggest hypomethylation and overexpression of ACE2, which is located on the X chromosome and encodes a functional receptor for the SARS-CoV-2 spike glycoprotein. Oxidative stress induced by viral infections exacerbates the DNA methylation defect in lupus, possibly resulting in further ACE2 hypomethylation and enhanced viremia. In addition, demethylation of interferon-regulated genes, NF{kappa}B, and key cytokine genes in lupus patients might exacerbate the immune response to SARS-CoV-2 and increase the likelihood of cytokine storm. These arguments suggest that inherent epigenetic dysregulation in lupus might facilitate viral entry, viremia, and an excessive immune response to SARS-CoV-2. Further, maintaining disease remission in lupus patients is critical to prevent a vicious cycle of demethylation and increased oxidative stress, which will exacerbate susceptibility to SARS-CoV-2 infection during the current pandemic. Epigenetic control of the ACE2 gene might be a target for prevention and therapy in COVID-19.

BackgroundLymphomatoid papulosis (LyP) is a self-healing CD30+ cutaneous lymphoproliferative disorder (CLPD) with paradoxical histology of a malignant lymphoma. Case reports and small patient series suggest an association of LyP with atopy. However, the prevalence of atopy depends on patients recall which is not always reliable. More objective criteria of atopy include skin reactivity to allergens and IgE reactivity to allergens. This study was undertaken to determine if atopy is prevalent in LyP patients using IgE specific antibodies to aeroallergens, and if Staphylococcal aureus enterotoxins might be a pathogenic factors for LyP as proposed for other skin disorders. MethodsThirty-one samples of CD30CLPD were tested for total serum IgE (IgE-t) and 10 IgE- specific airborne allergens with the Phadiatop multiallergen test, which if positive, is regarded as evidence of atopy. Sera was tested for IgE reactive against three Staphylococcal enterotoxins with superantigenic properties (SSAg-IgE). Control sera were obtained from adult subjects evaluated for rhino-sinusitis and a negative Phadiatop test. Patients history of atopy was obtained by retrospective chart review. FindingsNearly 50% of patients with the most common LyP types had a positive Phadiatop test and IgE-t was increased compared to non-atopic controls. Seven of 28 (25%) LyP patients had at least one SSAg-IgE at the concentration used to define serologic atopy ([≥] 0.35 kUa/L) compared to 3/52 (6%) controls (P= 0.028). TSST1-IgE was detected in 7 (23%) specimens of CD30CLPD, often together with SEB-IgE; SEA-IgE was not detected. TSST1-IgE exceeded the 0.35 kUa/L threshold in 3 (6%) controls. ConclusionsLyP patients have an increased prevalence of atopy as determined by the Phadiatop test and increased prevalence of SSAg-IgE compared to controls. Prevalence of serologic atopy exceeded that reported by patients medical history. The results support the hypothesis that an atopic diathesis and possibly SSAg contribute to the pathogenesis of LyP. SummaryContrary to patients recall of atopic disorders, IgE specific antibodies to aeroallergens, Staphylococcal aureus superantigens and total serum IgE are increased in patients with lymphomatoid papulosis.

Uncontrolled airway mucus is associated with diverse diseases. We hypothesized that the physical characteristics of infiltrating granulocytes themselves affect the clinical properties of mucus. Surgically obtained nasal mucus from patients with eosinophilic chronic rhinosinusitis (ECRS) and neutrophil-dominant non-eosinophilic chronic rhinosinusitis (non-ECRS) was assessed in terms of computed tomography (CT) density, viscosity, water content, wettability, and granulocyte-specific proteins. In an observational study, we found that nasal mucus from patients with ECRS had significantly higher CT density, viscosity, dry weight, and hydrophobicity than mucus from patients with non-ECRS. The levels of eosinophil-specific proteins in nasal mucus correlated with its physical properties. When isolated human eosinophils and neutrophils were stimulated to induce extracellular traps followed by aggregate formation, we found that cell aggregates showed physical and pathological findings that closely resembled mucus. Co-treatment with heparin (which slenderizes the structure of eosinophil extracellular traps) and DNase efficiently induced a reduction in the viscosity and hydrophobicity of both eosinophil aggregates and eosinophilic mucus. The present study highlights the pathogenesis of mucus stasis in infiltrated granulocyte aggregates from a new perspective. The combination of DNase and heparin might be a novel therapeutic modality against pathologic viscous eosinophilic mucus. One Sentence SummaryIntraluminal accumulation and activation of eosinophils contribute to the clinical properties of airway mucus and may serve as a therapeutic target.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibodies raised against nuclear antigens and whose production is promoted by autoreactive T follicular helper (TFH) cells. Basophils, by accumulating in secondary lymphoid organs (SLO), amplify autoantibody production and disease progression through mechanisms to be defined. Here, we demonstrate that a functional relationship between TFH cells and basophils occurs in SLO during lupus pathogenesis. On SLE patient blood basophils, PD-L1 expression was upregulated and associated with TFH and TFH2 cell expansions and with disease activity. In two distinct lupus-like mouse models, TFH cell pathogenic accumulation, maintenance and function, and disease activity were dependent on basophils and their expressions of PD-L1 and IL-4. Our study establishes a direct link between basophils and TFH cells in the SLE context that promotes autoreactive IgG production and lupus nephritis pathogenesis. Altering the basophil/TFH cell axis in the SLE context may represent a promising innovative intervention strategy in SLE.

RationaleNon-steroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD) is characterized by the clinical triad of hypersensitivity to NSAIDs, nasal polyposis, and asthma. The cells and mediators causing acute symptoms when driving the hypersensitivity reaction to acetylsalicylic acid (ASA) ingestion, remain poorly defined. ObjectivesTo investigate the dynamics of nasal mediators during ASA provocation in N-ERD patients before and twenty-four weeks after therapy with the IL-4 receptor alpha-blocking antibody dupilumab. MethodsNasal mucosal lining fluids of patients with N-ERD, chronic rhinosinusitis patients with nasal polyp (CRSwNP) and healthy disease controls were collected at selected time points up to two hours after ASA provocation. Analysis of thirty-three different inflammatory mediators as well as transcriptomic profiling was performed. In N-ERD patients, provocation was repeated after twenty-four weeks of dupilumab therapy. Measurements and Main ResultsSixty minutes after provocation with ASA, N-ERD patients showed a significant increase in type 2 associated cytokines (i.e., TSLP, IL-5, and eotaxin-3) as compared to the other patient groups. This effect was diminished after twenty-four weeks of dupilumab therapy and was independent of the development of ASA tolerance. Transcriptomics revealed dampened upregulation of type 2 associated pathways genes (i.e., AREG) as well as enhanced downregulation of lipid (i.e., ALOX15) and peroxisome metabolisms (i.e., NOS2) at ASA provocation after dupilumab therapy. ConclusionsTreatment with dupilumab leads to reduced nasal type 2 cytokine secretion and distinct changes in transcriptomic profile during ASA provocation, but changes in type 2 mediators show no association with tolerance development.