Possible role for IL-40 and IL-40-producing cells in the lymphocytic infiltrated salivary glands of patients with primary Sjögren's syndrome

Increased serum levels of IL-40 are associated with IgA and NETosis biomarkers in Covid-19 patients: IL-40 and infectious diseases

Interleukin 40 (IL-40) is a novel cytokine that has been associated with B lymphocytes, particularly IgA-secreting cells in gut mucosa. Considering mucosal association of IL-40, we aimed to determine serum IL-40 levels in patients with Covid-19. We compared IL-40 concentrations in healthy people to both patients with mild symptoms of SARS-CoV-2 infection and pneumonia. IL-40 was measured by ELISA. Serum IgA levels were tested by nephelometry. For the first time, we demonstrated that SARS-CoV-2 infection increased serum IL-40 levels significantly. The elevation of IL-40 in serum was related to severity of the infection. Therefore, IL-40 concentrations were quite higher in patients with symptoms of pneumonia. Our findings indicated that IgA and NETosis biomarkers were related with IL-40 increase. Based on these findings, we speculated that IL-40 would be associated with immune activities in the mucosa of the lungs of SARS-CoV-2-infected patients. This association may be linked to a mechanism that has a control on IgA and NETosis.

Inhibition of Interleukin-40 prevents multi-organ damage during sepsis by blocking NETosis

Despite intensive clinical and scientific efforts, the mortality rate of sepsis remains high due to the lack of precise biomarkers for patient stratification and therapeutic guidance. Interleukin 40 (IL-40), a novel cytokine with immune regulatory functions in human diseases, was elevated at admission in two independent cohorts of patients with sepsis. High levels of secreted IL-40 in septic patients were positively correlated with PCT, CRP, lactate (LDH), and Sequential Organ Failure Assessment (SOFA) scores, in which IL-40 levels were used to stratify the early death of critically ill patients with sepsis. Moreover, genetic knockout of IL-40 (IL-40-/-) improved outcomes in mice with experimental sepsis, as evidenced by attenuated cytokine storm, multiple-organ failure, and early mortality, compared with those of wild-type (WT) mice. Mechanistically, single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing (RNA-seq) have revealed that S100A8/9hi neutrophil influx into the peritoneal cavity along with neutrophil extracellular trap (NETs) formation accounts predominantly for the IL-40-mediated worsening of sepsis outcomes. Clinically, the IL-40 level was positively correlated with the NET-related MPO/dsDNA ratio in septic patients. Finally, with antibiotics (gentamycin), genetic knockout of IL-40 prevented polymicrobial sepsis fatalities more efficiently than without gentamycin treatment. In summary, these data reveal a novel prognostic strategy for sepsis and that IL-40 may serve as a novel therapeutic target for sepsis.

Serum IL-40 increases in patients with rheumatoid arthritis and correlates with some clinical characteristics and comorbidities

The role of Interleukin-40 (IL-40) in rheumatoid arthritis (RA) is not well understood, and this study was designed to explore serum IL-40 levels in RA patients to assess its potential as a disease biomarker. In this research, serum IL-40 levels were determined using enzyme-linked immunosorbent assay in 116 patients with RA, 40 with osteoarthritis (OA), 29 with systemic lupus erythematosus (SLE), and 66 healthy controls (HCs). Paired serum samples were collected from 86 of the 116 patients treated during follow-up visits at week 12. Group comparison analysis showed that serum IL-40 levels were significantly higher in patients with RA than in HCs, and the areas under the curve for IL-40 were 0.688, 0.865, and 0.870 for distinguishing patients with RA from HCs and those with OA and SLE, respectively. Furthermore, in RA, serum IL-40 levels were lower in patients with comorbidities of cardiovascular diseases or OA. Correlation analyses revealed that serum IL-40 levels were positively associated with RA-related autoantibodies and coagulation-related indicators, whereas no correlation was observed with disease activity-associated factors. When comparing paired samples, treatment with TNF inhibitors (TNFi) significantly reduced serum IL-40 levels, emphasizing its potential as a treatment guide.

Netosis and trained immunity in tick-borne diseases: a possible pathogenetic role

Various types of pathogens transmitted by ticks elicit distinct immune responses just like the emerging α-Gal syndrome that is associated with allergic reactions to tick bites. The mechanisms of Neutrophil Extracellular Traps release (called NETosis) and trained immunity in response to tick-borne microbes have not been extensively investigated. In our paper, we explored the intricate interplay of NETosis and trained immunity within the realm of infectious diseases triggered by tick bites and their possible pathogenetic role in autoimmunity. We conducted an extensive literature search to identify studies for this review, considering articles and reviews published in English within the last years. Additionally, we scrutinized the references of all included papers and relevant review articles to ensure comprehensive coverage. We shed light on a plausible correlation between these innate immune responses and their potential implication in certain pathological conditions, with a specific focus on some autoimmune diseases. These findings offer new perspectives for a more profound comprehension of the immunopathogenesis of certain autoimmune-like signs where clinicians should include Tick-Borne Diseases (TBDs) in their differential diagnoses, in those geographical areas of tick infestation.

IL-40 is up-regulated in the synovial fluid and cartilage of osteoarthritis patients and contributes to the alteration of chondrocytes phenotype in vitro

INTRODUCTION

IL-40 is a novel cytokine associated with autoimmune connective tissue disorders such as rheumatoid arthritis (RA) or Sjögren syndrome. We have previously shown an accumulation of IL-40 in the RA joint and its expression by immune cells and fibroblasts. Therefore, we aimed to assess the role of IL-40 in association with hyaline cartilage and chondrocyte activity.

METHODS

Immunohistochemistry was employed to detect IL-40 in paired samples of loaded and unloaded regions of osteoarthritis (OA) cartilage (n=5). Synovial fluid IL-40 was analysed by ELISA in OA (n=31) and control individuals after knee injury (n=34). The impact of IL-40 on chondrocytes was tested in vitro.

RESULTS

IL-40 was found in chondrocytes of the superficial zone of the OA cartilage, both in loaded and unloaded explants. Additionally, only biopsies from loaded explants showed significant IL-40 positivity in transitional zone chondrocytes. Levels of IL-40 were significantly elevated in the synovial fluid from OA patients compared to controls (p<0.0009) and correlated with synovial fluid leukocyte counts in OA (r=0.444, p=0.014). Chondrocytes exposed to IL-40 dose dependently increased in the secretion of pro-inflammatory cytokines IL-6 (p<0.0001) and IL-8 (p=0.004). Moreover, a dose dependent up-regulation of matrix degrading metalloproteinases MMP-1 (p=0.004), MMP-3 (p=0.031) and MMP-13 (p=0.0002) upon IL-40 treatment was observed in contrast to untreated chondrocytes.

CONCLUSION

This study is the first to demonstrate the accumulation of IL-40 in OA cartilage and its up-regulation in the synovial fluid of OA patients compared to controls. In addition, extracellular IL-40 appears to play a role in promoting inflammation and cartilage destruction by driving chondrocyte behaviour towards a more aggressive phenotype.

A Comprehensive Review on the Role of Interleukin-40 as a Biomarker for Diagnosing Inflammatory Diseases

Interleukins are a group of proteins that have a wide range of complex functions and are believed to be involved in several diseases and conditions. In particular, interleukin-40 (IL-40) is a recently identified cytokine associated with B cells that was first introduced by Catalan et al. in 2017. This cytokine has several roles in the body, including functioning in the formation of B cells in the bone marrow, IgA production, and expression in the intestinal microbiome. Moreover, IL-40 appears to be involved in numerous autoimmune and inflammatory conditions, such as rheumatoid arthritis, systemic lupus erythematosus, primary Sjogren's syndrome, ankylosing spondylitis, type 2 diabetes, Graves' disease, and hepatic cell carcinoma. Our understanding of this molecule is quite restricted due to its novelty. However, because of its inflammatory characteristics, there is a high probability that it contributes to a variety of inflammatory disease complications. The aim of the present review is to highlight all available data on the importance of assessing IL-40 levels in human diseases up to now, which could be used as a diagnostic biomarker for the onset or progression of numerous inflammatory diseases.