OBJECTIVE: Posttranslational modifications (PTMs) of proteins are crucial for regulating various biological processes. However, protein alteration via PTMs, and consequently, the creation of new epitopes, can induce abnormal autoimmune responses in predisposed individuals. Immunopathogenesis of several rheumatic diseases, including the most common childhood form, juvenile idiopathic arthritis (JIA), is associated with the generation of autoantibodies against such modified proteins. Dysregulated generation of neutrophil extracellular traps (NETs) can be a source of post-translationally altered proteins. Thus, we investigated the role of PTMs and the presence of NET-associated markers in JIA patients. METHODS: We recruited 30 pediatric patients with JIA (20 with active disease and 10 in remission) and 30 healthy donors. The serum concentrations of citrullinated histone H3 (citH3), peptidyl arginine deiminases (PADs), and NET-related products were detected using ELISA, and the number of citH3+ neutrophils was assessed using flow cytometry. RESULTS: The serum levels of citH3 and PADs were higher in active as well as in remission JIA patients than in healthy donors. Similarly, the number of citH3+ neutrophils was higher in the peripheral blood of patients with JIA, implying an enhanced process of NETosis. This was effectively reflected by elevated serum levels of NET-associated products, such as neutrophil elastase, LL37, and cell-free DNA-histone complexes. Additionally, 16.7% of active JIA patients were seropositive for carbamylated autoantibodies, the levels of which declined sharply after initiation of anti-TNFα therapy. CONCLUSION: Collectively, our data suggest that the accelerated process of NETosis and PTMs in JIA may result in the generation of anti-citrullinated/carbamylated autoantibodies against various epitopes later in life, which could be prevented by effectively regulating inflammation using immune therapy.

• Keywords
• NETosis, carbamylation, citrullination, histone, juvenile idiopathic arthritis, neutrophil, peptidyl arginine deiminases (PAD),
• Publication type
• Journal Article MeSH

COVID-19, caused by SARS-CoV-2 virus, emerged as a pandemic disease posing a severe threat to global health. To date, sporadic studies have demonstrated that innate immune mechanisms, specifically neutrophilia, NETosis, and neutrophil-associated cytokine responses, are involved in COVID-19 pathogenesis; however, our understanding of the exact nature of this aspect of host-pathogen interaction is limited. Here, we present a detailed dissection of the features and functional profiles of neutrophils, dendritic cells, and monocytes in COVID-19. We portray the crucial role of neutrophils as drivers of hyperinflammation associated with COVID-19 disease via the shift towards their immature forms, enhanced degranulation, cytokine production, and augmented interferon responses. We demonstrate the impaired functionality of COVID-19 dendritic cells and monocytes, particularly their low expression of maturation markers, increased PD-L1 levels, and their inability to upregulate phenotype upon stimulation. In summary, our work highlights important data that prompt further research, as therapeutic targeting of neutrophils and their associated products may hold the potential to reduce the severity of COVID-19.

• Keywords
• COVID-19, IFN alpha, PD-L1, SARS-CoV-2, cytokine storm, degranulation, dendritic cells, innate immunity, monocytes, neutrophils,
• MeSH
• B7-H1 Antigen genetics   metabolism   MeSH
• COVID-19 MeSH
• Cytokines genetics   metabolism   MeSH
• Dendritic Cells immunology   MeSH
• Adult MeSH
• Immunophenotyping MeSH
• Coronavirus Infections blood   immunology   MeSH
• Cells, Cultured MeSH
• Middle Aged MeSH
• Humans MeSH
• Monocytes immunology   MeSH
• Neutrophils immunology   MeSH
• Pandemics MeSH
• Immunity, Innate MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Pneumonia, Viral blood   immunology   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• B7-H1 Antigen MeSH
• CD274 protein, human MeSH Browser
• Cytokines MeSH

X-linked inhibitor of apoptosis (XIAP) is the most potent human inhibitor of apoptosis, and is also involved in NOD2-dependent NFκB and MAPK signalling cascade activation. The absence or defective function of XIAP leads to the development of a rare and severe primary immunodeficiency known as X-linked lymphoproliferative syndrome type 2 (XLP-2), which is characterized by a triad of clinical manifestations, including a high incidence of haemophagocytic lymphohistiocytosis (HLH), lymphoproliferation and inflammatory bowel disease (IBD), usually with very early onset. Here, we present a novel XIAP mutation identified in a patient with atypical adult-onset IBD complicated by relapsing HLH, splenomegaly and sarcoid-like disease. The c.266delA mutation in the XIAP gene creates a premature stop codon, and causes a severe reduction in XIAP protein expression. The mutation is also associated with impaired spontaneous and staurosporine- and PMA-induced apoptosis accompanied by significantly increased expression of pro-apoptotic genes. We also confirmed the negative impact of this particular XIAP mutation on NOD2-dependent NFκB and MAPK activation, while NOD2-independent activation was found to be unaffected. Moreover, we assume that the mutation has an impact on the overproduction of IL-12 and IFNγ, the shift towards the Th1 immune response and increased numbers of central memory and effector memory CD4+ and CD8+ T cells. All these changes contribute to immune dysregulation and the clinical manifestation of XLP-2.

• MeSH
• Apoptosis MeSH
• Crohn Disease genetics   pathology   MeSH
• Adult MeSH
• Humans MeSH
• Mutation MeSH
• Nod2 Signaling Adaptor Protein metabolism   MeSH
• Signal Transduction MeSH
• X-Linked Inhibitor of Apoptosis Protein metabolism   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Case Reports MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• NOD2 protein, human MeSH Browser
• Nod2 Signaling Adaptor Protein MeSH
• X-Linked Inhibitor of Apoptosis Protein MeSH
• XIAP protein, human MeSH Browser

Interleukin 27 (IL-27), a member of the IL-12 family, is important for T cell differentiation; however, little is known about its effect on dendritic cells (DCs). IL-27 can activate multiple signaling cascades, including the JAK/STAT pathway, and depending on the setting it can both promote and antagonize inflammatory responses. An anti-inflammatory function of IL-27 has been reported in several autoimmune diseases; however, in type 1 diabetes (T1D), an autoimmune disease where autoreactive cytotoxic T cells attack insulin-producing beta cells, IL-27 has been shown to have a dual role and contradictory effects. Here, we show impaired IL-27 signaling in a large cohort of T1D patients (n = 51) compared to age- and gender-matched healthy donors. Increased expression of the IL-27 receptor subunit IL-27Ralpha mRNA in purified myeloid DCs (mDCs), detected by gene expression microarrays was mirrored by enhanced signal transduction in T1D mDCs in response to IL-27 stimulation. Higher STAT phosphorylation in T1D patients was also accompanied by elevated expression of the inhibitory molecules PD-L1, PD-L2 and PD-1, which may suggest not only immunomodulatory mechanisms of IL-27 in T1D but also a compensatory effort of T1D dendritic cells against the ongoing inflammation.

• MeSH
• B7-H1 Antigen genetics   metabolism   MeSH
• Dendritic Cells immunology   MeSH
• Diabetes Mellitus, Type 1 genetics   immunology   metabolism   MeSH
• Adult MeSH
• Phosphorylation MeSH
• Interleukins genetics   metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Receptors, Interleukin genetics   metabolism   MeSH
• Oligonucleotide Array Sequence Analysis MeSH
• Aged MeSH
• Signal Transduction * MeSH
• Gene Expression Profiling methods   MeSH
• Case-Control Studies MeSH
• STAT3 Transcription Factor metabolism   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• B7-H1 Antigen MeSH
• CD274 protein, human MeSH Browser
• IL27RA protein, human MeSH Browser
• Interleukins MeSH
• MYDGF protein, human MeSH Browser
• Receptors, Interleukin MeSH
• STAT3 protein, human MeSH Browser
• STAT3 Transcription Factor MeSH

Inflammasomes are large protein complexes involved in the maturation of IL-1β, a cytokine associated with the pathophysiology of type 1 diabetes (T1D). The data presented in this article focused on the role of inflammasomes in DNA recognition in T1D patients. This data extend knowledge on DNA sensing in T1D patients and relate to our research paper "Monocytes contribute to DNA sensing through the TBK1 signaling pathway in type 1 diabetes patients" Zentsova et al., 2009. To examine inflammasome involvement, we blocked the known mechanism of inflammasome activation - potassium efflux via various approaches: 1) high concentration of KCl; 2) Glybenclamide, which selectively blocks the ATP sensitive K+ channel; 3) KN-62, an inhibitor of P2X7 receptor, which activates K+ channel after ATP binding. Moreover, we used an inhibitor which blocks Nod-like receptor family containing pyrin domain 3 (NLRP3) inflammasome. In T1D patients, we show that secretion of cytokines IL-1β, TNFα, IL-6 and IFNα after microbial DNA stimulation is promoted by potassium efflux and is not dependent on P2X7 receptor signaling. Surprisingly, the microbial DNA induced IL-1β release was independent of NLRP3.

• Keywords
• DNA, Glybenclamide, Inflammasomes, Monocytes, NLRP3, Type 1 diabetes,
• Publication type
• Journal Article MeSH
• Comment MeSH