Elevated production of IL-36α in chronic hepatitis B virus-infected patients correlates with viral load

Correlation between the interleukin-36 subfamily and gut microbiota in patients with liver cirrhosis: Implications for gut-liver axis imbalance

BACKGROUND

Liver cirrhosis (LC) affect millions of people worldwide. The pathogenesis of cirrhosis involves complex interactions between immune responses and gut microbiota. Recent studies have highlighted the role of the interleukin-36 (IL-36) subfamily in inflammation and immune regulation. However, the relationship between serum IL-36 subfamily levels and gut microbiota in cirrhosis patients remains unclear. This study aimed to explore the clinical significance of serum IL-36 subfamily levels and their association with gut microbiota in cirrhosis patients.

AIM

To explore the clinical significance of serum IL-36 subfamily levels and their relationship with gut microbiota among cirrhosis patients.

METHODS

Sixty-one cirrhosis patients were enrolled from Lihuili Hospital of Ningbo University from May 2022 to November 2023 as the LC group and 29 healthy volunteers as the healthy control (HC) group. The serum expressions of IL-36α, IL-36β, IL-36γ, IL-36Ra, and IL-38 were measured through ELISA, while 16S rRNA gene sequencing was employed to rate microbial community in human fecal samples.

RESULTS

The serum levels of IL-36α, IL-36γ, IL-36Ra, and IL-38 in the LC group remarkably exceeded those in the HC group (P < 0.05). IL-36α, IL-36γ, and IL-38 were related positively to the Child-Pugh score (P < 0.05) and prominently exceeded those in the Child-Pugh C group (P < 0.05). The absolute abundance of harmful bacteria (Bacteroides, Bifidobacterium, Faecalibacterium) remarkably rose, while the beneficial bacteria (Firmicutes, Bacteroides, Escherichia-Shigella) notably decreased in the LC group (P < 0.05). IL-36α, IL-36γ, and IL-38 related positively to Lactobacillus (P < 0.05), while IL-38 negatively related to Fusicatenibacter (P < 0.05).

CONCLUSION

IL-36γ and IL-38 show promise as potential biomarkers for LC progression, but further validation is required.

Interleukin-36gamma Mediates the In Vitro Activation of CD8+ T Cells from Patients Living with Chronic Human Immunodeficiency Virus-1 Infection

Interleukin-36 (IL-36) signaling plays an important role in promoting CD8+ T cell-mediated antitumor immune responses. The role of IL-36 signaling in CD8+ T cells that are involved in host immune responses during human immunodeficiency virus-1 (HIV-1) infection has not been characterized. Sixty-one patients living with chronic HIV-1 infection and 23 controls were enrolled in this study. The levels of IL-36 cytokine family members were measured by enzyme-linked immunosorbent assay. Purified CD8+ T cells were stimulated with recombinant IL-36gamma (1 or 10 ng/mL). The expression of inhibitory receptors, the secretion of cytotoxic molecules and interferon-gamma, and the mRNA levels of apoptosis-related ligands were assessed to evaluate the effect of IL-36gamma on CD8+ T cell function in vitro. There were no significant differences in IL-36alpha, IL-36beta, or IL-36 receptor antagonist levels between patients living with chronic HIV-1 infection and controls. Plasma IL-36gamma levels were reduced in patients living with chronic HIV-1 infection. Perforin, granzyme B, and granulysin secretion, as well as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas ligand (FasL) mRNA expression, but not programmed death-1 (PD-1) or cytotoxic T lymphocyte-associated protein-4 (CTLA-4) expression was downregulated in CD8+ T cells from patients living with chronic HIV-1 infection. The addition of both 1 and 10 ng/mL IL-36gamma enhanced perforin, granzyme B, granulysin, and interferon-gamma secretion by CD8+ T cells without affecting PD-1/CTLA-4 or TRAIL/FasL mRNA expression in CD8+ T cells from patients living with chronic HIV-1 infection. The addition of 1 ng/mL IL-36gamma also promoted perforin and granzyme B secretion by HIV-1-specific CD8+ T cells from patients living with chronic HIV-1 infection. The reduced IL-36gamma levels in patients living with chronic HIV-1 infection might be insufficient for the activation of CD8+ T cells, leading to CD8+ T cell exhaustion.

Interleukin-36γ is causative for liver damage upon infection with Rift Valley fever virus in type I interferon receptor-deficient mice

Type I interferons (IFN) are pro-inflammatory cytokines which can also exert anti-inflammatory effects via the regulation of interleukin (IL)-1 family members. Several studies showed that interferon receptor (IFNAR)-deficient mice develop severe liver damage upon treatment with artificial agonists such as acetaminophen or polyinosinic:polycytidylic acid. In order to investigate if these mechanisms also play a role in an acute viral infection, experiments with the Bunyaviridae family member Rift Valley fever virus (RVFV) were performed. Upon RVFV clone (cl)13 infection, IFNAR-deficient mice develop a severe liver injury as indicated by high activity of serum alanine aminotransferase (ALT) and histological analyses. Infected IFNAR-/- mice expressed high amounts of IL-36γ within the liver, which was not observed in infected wildtype (WT) animals. In line with this, treatment of WT mice with recombinant IL-36γ induced ALT activity. Furthermore, administration of an IL-36 receptor antagonist prior to infection prevented the formation of liver injury in IFNAR-/- mice, indicating that IL-36γ is causative for the observed liver damage. Mice deficient for adaptor molecules of certain pattern recognition receptors indicated that IL-36γ induction was dependent on mitochondrial antiviral-signaling protein and the retinoic acid-inducible gene-I-like receptor. Consequently, cell type-specific IFNAR knockouts revealed that type I IFN signaling in myeloid cells is critical in order to prevent IL-36γ expression and liver injury upon viral infection. Our data demonstrate an anti-inflammatory role of type I IFN in a model for virus-induced hepatitis by preventing the expression of the novel IL-1 family member IL-36γ.

The Pro-Tumor Biological Function of IL-36α Plays an Important Role in the Tumor Microenvironment of HCC

Purpose

To investigate the role of IL-36 in the tumorigenesis of hepatocellular carcinoma (HCC). IL-36 composed of a natural antagonist (IL-36Ra) and three agonists (IL-36α, -β, -γ) that stimulate inflammation by binding to a common receptor consisting of IL-36R and IL-1RAcP. HCC is a common malignancy associated with high morbidity and mortality, often diagnosed at later stages. Although the exact role of IL-36α in HCC remains controversial, it is hypothesized that it may play a significant role in the development and progression of this cancer.

Materials and Methods

In the current study, we measured both circulating and intrahepatic levels of IL-36α from HCC patients and healthy controls, using ELISA. The association between IL-36 and the differentiation of HCC was determined. Furthermore, the role IL-36 in both HCC and non-HCC cell lines was evaluated in vitro.

Results

Circulating and intra-hepatic IL-36α was inversely correlated with differentiation of HCC, suggesting that IL-36α contribute to protection during the development of HCC. Based on bioinformatics, miR-27b-3p is closely related to downstream IL-36α. Thus, we determined miR-27b-3p expression in HCC tissues, showing upregulated miR-27b-3p was inversely correlated with IL-36α in HCC, perhaps via CXCL1 in HCC cells. It was confirmed that IL-36α inhibited HCC proliferation, viability and migration in vitro, consistent with reduced the expression of cytokines IL-1β, IL-18, implying that IL-36α inhibited the possible involvement of pyroptosis.

Conclusion

Our data suggests that IL-36α may be a potential therapeutic target and a prediction biomarker for the management of HCC.

The role of IL-36 subfamily in intestinal disease

Interleukin (IL)-36 is a subfamily, of the IL-1 super-family and includes IL-36α, IL-36β, IL-36γ, IL-38 and IL-36Ra. IL-36 cytokines are involved in the pathology of multiple tissues, including skin, lung, oral cavity, intestine, kidneys and joints. Recent studies suggest that IL-36 signaling regulates autoimmune disease in addition to antibacterial and antiviral responses. Most research has focused on IL-36 in skin diseases such as psoriasis, however, studies on intestinal diseases are also underway. This review outlines what is known about the bioactivity of the IL-36 subfamily and its role in the pathogenesis of intestinal diseases such as inflammatory bowel disease, colorectal cancer, gut dysbacteriosis and infection, and proposes that IL-36 may be a target for novel therapeutic strategies to prevent or treat intestinal diseases.

The Role of IL-36 in Infectious Diseases: Potential Target for COVID-19?

IL-36 is a member of the interleukin 1 cytokine family, which is currently experiencing a renaissance due to the growing understanding of its context-dependent roles and advances in our understanding of the inflammatory response. The immunological role of IL-36 has revealed its profound and indispensable functional roles in psoriasis, as well as in several inflammatory diseases, including inflammatory bowel disease (IBD), systemic lupus erythematosus, rheumatoid arthritis (RA) and cancer. More recently, an increasing body of evidence suggests that IL-36 plays a crucial role in viral, bacterial and fungal infections. There is a growing interest as to whether IL-36 contributes to host protective immune responses against infection as well as the potential implications of IL-36 for the development of new therapeutic strategies. In this review, we summarize the recent progress in understanding cellular expression, regulatory mechanisms and biological roles of IL-36 in infectious diseases, which suggest more specific strategies to maneuver IL-36 as a diagnostic or therapeutic target, especially in COVID-19.

Interleukin-36 in Infectious and Inflammatory Skin Diseases

Interleukin-36 (IL-36) comprises to a cytokine family consisting of four isoforms IL-36α, IL-36β, IL-36γ, and IL-36 receptor antagonist (IL-36 Ra). These IL-36 cytokines, in turn, belong to the IL-1 superfamily. The IL-36 receptor (IL-1R6) is functional as a heterodimer formed of IL-1R6 and IL-1 receptor accessory protein (IL-1RAcP). IL-36α, IL-36β, and IL-36γ are regarded as pro-inflammatory ligands and IL-36 Ra as well as IL-38 as anti-inflammatory ligands of IL-1R6. IL-36 cytokines are mainly expressed on the barrier sites of the body e.g., bronchial, intestinal, and dermal epithelium. One of their most important biological functions is the bridging of innate and adaptive immune responses. A disturbed balance between pro-inflammatory and anti-inflammatory branches easily leads to inflammation of the corresponding tissue. The most prominent example for an altered IL-36 expression is the spectrum of psoriasis. In addition to inflammatory dermatoses, IL-36 also seems to play a role in infectious dermatoses. Microbial triggers, especially Staphylococcus aureus infection, increase the production of pro-inflammatory IL-36 cytokines and initiate/promote the inflammation of skin lesions. Due to the discovery of IL-36 as an important immune mediator, it has already been possible to develop important diagnostic tools for dermatitis. Not only in the field of inflammatory skin diseases, but also in pulmonary and intestinal inflammation, there is evidence that IL-36 cytokines might have diagnostic and/or therapeutic relevance.