The composition and signaling of the IL-35 receptor are unconventional

IL-12 family cytokines and autoimmune diseases: A potential therapeutic target?

In recent years, the discovery of IL-12 family cytokines, which includes IL-12, IL-23, IL-27, IL-35, and IL-39, whose biological functions directly or indirectly affect various autoimmune diseases. In autoimmune diseases, IL-12 family cytokines are aberrantly expressed to varying degrees. These cytokines utilize shared subunits to influence T-cell activation and differentiation, thereby regulating the balance of T-cell subsets, which profoundly impacts the onset and progression of autoimmune diseases. In such conditions, IL-12 family members are aberrantly expressed to varying degrees. By exploring their immunomodulatory functions, researchers have identified varying therapeutic potentials for each member. This review examines the physiological functions of the major IL-12 family members and their interactions, discusses their roles in several autoimmune diseases, and summarizes the progress of clinical studies involving monoclonal antibodies targeting IL-12 and IL-23 subunits currently available for treatment.

Intestinal permeability of N-acetylcysteine is driven by gut microbiota-dependent cysteine palmitoylation

Trillions of intestinal microbiota are essential to the permeability of orally administered drugs. However, identifying microbial-drug interactions remains challenging due to the highly variable composition of intestinal flora among individuals. Using single-pass intestinal perfusion (SPIP) platform, we establish the microbiota-based permeability screening framework involving germ-free (GF) and specific-pathogen-free (SPF) rats to compare in-situ Peff-values and metabolomic profiles of 32 orally administered drugs with disputable classifications of permeability, prior to the verifications of bioorthogonal chemistry and LC-MS/MS. In contrast with SPF controls, N-Acetylcysteine (NAC) exhibits significantly increased permeability in GF rats, which is inversely related to reduced cysteine-3-ketosphinganine by Bacteroides. To further validate these microbiome features, we integrate clinical descriptors from a prospective cohort of 319 participants to optimize a 15-feature eXtreme Gradient Boosting (XGB) model, which reveal that cysteine palmitoylation by intestinal microbiota has significantly affected NAC permeability. By comparison of net reclassification improvement (NRI) index, this machine learning (ML) model of clinical prediction model encompassing intestinal microbial features outperforms other three commercial models in predicting NAC permeability. Here we have developed an intestinal microbiota-based strategy to evaluate uncharacterized NAC permeability, thus accounting for its discordant biopharmaceutics classification.

Low IL-35 Expression in CSF is Associated with Neuro-Behcet Disease: Comparative Analysis Between Parenchymal and Non-Parenchymal NBD

BACKGROUND

IL-35 is a recently discovered immunoregulatory cytokine that inhibits inflammatory cytokines by suppressing their lineage-specific transcription factors. The objective of this study was to investigate the expression of IL-35 in the cerebrospinal fluid (CSF) of patients with Neuro-Behçet Disease (NBD). An immuno-comparative analysis was performed between parenchymal NBD (pNBD) and non-parenchymal NBD (npNBD).

METHODS

We are investigating CSF IL-35 levels in 45 patients with (NBD), comprising 25 patients with pNBD and 20 with npNBD, compared to 27 patients with multiple sclerosis (MS) and 20 patients with non-inflammatory neurological diseases (NIND). We assessed the inflammatory cytokines (IL-1α, IL-18, IL-33, IL-36), Foxp3 and CD4+ CD25+ Foxp3+ regulatory Treg T cells (Tregs). The following methodologies were employed: flow cytometry, ELISA, and real-time polymerase chain reaction (RT-PCR). For RT-PCR analysis, we calculated relative gene expression in target genes using the comparative CT method with the equation 2-ΔΔCt. We employed a receiver operating characteristic (ROC) curve to investigate the predictive value of IL-35 levels.

RESULTS

Protein and relative mRNA expression of IL-35 were significantly decreased in NBD and MS patients compared to the NIND group. Significantly lower CSF IL-35 mRNA (p = 0.0001) and protein (p = 0.0004) were observed in patients with pNBD compared to npNBD. The study revealed that NBD patients exhibited low Treg counts, and a significant positive correlation was identified between Treg numbers and CSF IL-35 (r = 0.554, p = 0.0001). Negative associations were observed between Tregs and CRP (r =- 0.518; p = 0.0001) and ESR (r = -0.571; p = 0.0001) in NBD. Levels of the pro-inflammatory mediators were found to be elevated in contrast to a low Foxp3 level in NBD, which was more reduced in pNBD compared to npNBD. In vitro cultured memory T cells from pNBD patients stimulated with LPS showed high levels of IL-1α, IL-18, IL-33, IL-36 and low levels of Foxp3 and IL-35 measured in the culture medium. After the addition of recombinant human IL-35 (rhIL-35), Foxp3 and IL-35 were significantly increased and inflammatory cytokine levels were reduced. These results suggest that rhIL-35 may induce a regulatory effect on Foxp3 and IL-35.

CONCLUSION

These findings imply a critical reduction of IL-35 in pNBD patients. The combined protein and gene expression of the tested inflammatory cytokines suggest that there are distinct inflammatory mechanisms governing the central nervous system in pNBD. Further work is essential for the development of targeted interventions for the effective treatment of patients.

Interleukin-35 inhibits NETs to ameliorate Th17/Treg immune imbalance during the exacerbation of cigarette smoke exposed-asthma via gp130/STAT3/ferroptosis axis

Cigarette smoke (CS) exposure amplifies neutrophil accumulation. IL-35, a novel cytokine with anti-inflammatory properties, is involved in protection against asthma. However, the biological roles of neutrophils and the precise molecular mechanisms of IL-35 in CS exposed-asthma remain unclear. We showed that the exacerbation of CS exposed-asthma leads to dramatically increased neutrophil counts and an imbalance in DC-Th17/Treg immune responses. RNA sequencing revealed that NETs, part of a key biological process in neutrophils, were significantly upregulated in the context of CS exposed-asthma exacerbation and that IL-35 treatment downregulated NET-associated gene expression. Targeted degradation of NETs, rather than neutrophil depletion, alleviated the CS exposed-asthma. Mechanistically, STAT3 phosphorylation promoted ferroptosis, exacerbating NET release, which in turn enhanced dendritic cell (DC) antigen presentation, activated T cells, and specifically promoted Th17 cell differentiation while inhibiting Treg cells. IL-35 acting on the gp130 receptor alleviated STAT3-mediated ferroptosis-associated NET formation. In summary, our study revealed a novel mechanism by which IL-35 inhibited NET formation, subsequently alleviating neutrophilic inflammation and restoring the DC-Th17/Treg imbalance in CS exposed-asthma, highlighting the potential of IL-35 as a targeted therapeutic strategy.

Increased Peripheral Interleukin-35 Suppresses CD4+ T and CD8+ T-Cell Activity in Patients Living with Chronic Human Immunodeficiency Virus-1 Infection

Interleukin-35 (IL-35) has an immunosuppressive function through the regulation of immune cells during infectious diseases, autoimmune disorders, and cancers. The modulatory role of IL-35 in T lymphocytes, which are involved in host immune responses during human immunodeficiency virus-1 (HIV-1) infection, has not been elucidated. The aim of the current study was to investigate the role of regulatory function of IL-35 to T-cell activity in patients living with chronic HIV-1 infection. Sixty-seven patients living with chronic HIV-1 infection and 17 controls were enrolled in the study. IL-35 levels were measured via an enzyme-linked immunosorbent assay. Purified CD4+ and CD8+ T cells were stimulated with recombinant human IL-35. The secretion of cytokines and cytotoxic molecules, the mRNA levels of IL-35 receptor subunits and transcription factors, the expression of immune checkpoint molecules, and cell proliferation were assessed to evaluate the effect of IL-35 on T lymphocyte function in vitro. Compared with controls, patients living with chronic HIV-1 infection presented increased plasma IL-35 levels. IL-35 stimulation did not affect either the expression of IL-35 receptor subunits or the proliferation of CD4+ and CD8+ T cells from either patients living with chronic HIV-1 infection or controls. IL-35 stimulation downregulated transcription factor mRNA expression and cytokine secretion by CD4+ T cells as well as cytotoxic molecule production by CD8+ T cells from both patients living with chronic HIV-1 infection and controls. This process was accompanied by increased expression of immune checkpoint molecules on CD4+ and CD8+ T cells. The addition of IL-35 also reduced perforin and granzyme B secretion by HIV-1-specific CD8+ T cells from patients living with chronic HIV-1 infection. Increased plasma IL-35 in patients living with chronic HIV-1 infection might dampen the activation of CD4+ and CD8+ T cells, leading to T-cell exhaustion.

Patients with periodontal disease demonstrates changes in purinergic and inflammatory markers in PBMCs, serum and saliva

Periodontal disease (PD) is characterized by the presence of a chronic inflammatory process, due to the accumulation of bacterial biofilm and the host's response to these pathogens, resulting in the destruction of the supporting tissues of dental structures. Studies have revealed that components of the purinergic system and inflammation are related to the development and progression of PD. The objective was to evaluate periodontal clinical parameters, modulation of the purinergic system and inflammation in patients with PD, compared to individuals without the disease. This is a cross-sectional study with 25 healthy individuals (CT group) and 57 individuals with PD, where blood and saliva collection and isolation of blood components were carried out. The results showed that there was a significant reduction in the hydrolysis of adenosine triphosphate (ATP; p < 0.0001), adenosine diphosphate (ADP; p < 0.05) and adenosine monophosphate (AMP; p < 0.01) in peripheral blood mononuclear cells (PBMCs) from individuals in the PD group compared to the CT group, indicating that individuals with PD showed reduced NTPDase 1 and Ecto-5'-nucleotidase activity. Adenosine deaminase activity in saliva (p < 0.0001) and serum p < 0.05) from individuals with PD were significantly higher compared to the CT group. Extracellular ATP and the serum concentration of C-Reactive Protein showed a statistically significant increase in the PD group ((p < 0.0001 and p < 0.001, respectively). Therefore, the enzymes of the purinergic system are present in the modulation of PD, leading individuals affected by the disease to a pro-inflammatory state, hindering the action of the immune system and increasing serum markers of inflammation.

Inflammation in glomerular diseases

The structural and functional integrity of glomerular cells is critical for maintaining normal kidney function. Glomerular diseases, which involve chronic histological damage to the kidney, are related to injury to glomerular cells such as endothelial cells, mesangial cells (MCs), and podocytes. When faced with pathogenic conditions, these cells release pro-inflammatory cytokines such as chemokines, inflammatory factors, and adhesion factors. These substances interact with glomerular cells through specific inflammatory pathways, resulting in damage to the structure and function of the glomeruli, ultimately causing glomerular disease. Although the role of inflammation in chronic kidney diseases is well known, the specific molecular pathways that result in glomerular diseases remain largely unclear. For a long time, it has been believed that only immune cells can secrete inflammatory factors. Therefore, targeted therapies against immune cells were considered the first choice for treating inflammation in glomerular disease. However, emerging research indicates that non-immune cells such as glomerular endothelial cells, MCs, and podocytes can also play a role in renal inflammation by releasing inflammatory factors. Similarly, targeted therapies against glomerular cells should be considered. This review aims to uncover glomerular diseases related to inflammation and pathways in glomerular inflammation, and for the first time summarized that non-immune cells in the glomerulus can participate in glomerular inflammatory damage by secreting inflammatory factors, providing valuable references for future strategies to prevent and treat glomerular diseases. More importantly, we emphasized targeted glomerular cell therapy, which may be a key direction for the future treatment of glomerular diseases.

Contribution of interleukins in the regulation of teleost fish immunity: A review from the perspective of regulating macrophages

Interleukins (ILs) are potent secreted regulators of a wide range of cell types and cellular activities, particularly in the immune system. They are able to participate in intercellular communication in homeostasis and disease, thereby exerting immune functions. Macrophages serve as the innate immune cells of vertebrates and play a pivotal role in defending against and eliminating external pathogens. In mammals, the immune response mounted by macrophages is intricately linked to ILs. Given the fact that teleost fish have evolved an innate immune system that closely resembles those of mammals, particularly in terms of the functionality of macrophages, raises the intriguing possibility that the regulatory function of ILs in macrophage-mediated immunity might be evolutionarily conserved across both mammal and teleost fish lineages. Consequently, from the perspective of interleukin regulation of macrophages, this review outlines the relationship between ILs and macrophages in teleost fish, and elucidates the regulatory role of ILs of immune cell function in teleost fish, thereby contributing to our understanding of the key role of these cytokines in the prevention and control of aquaculture diseases.

Systematic Review of Interleukin-35 in Endothelial Dysfunction: A New Target for Therapeutic Intervention

Endothelial dysfunction is a significant factor in the pathogenesis of various diseases. In pathological states, endothelial cells (ECs) undergo activation, resulting in dysfunction characterized by the stimulation of inflammatory responses, oxidative stress, cell proliferation, blood coagulation, and vascular adhesions. Interleukin-35 (IL-35), a novel member of the IL-12 family, is primarily secreted by regulatory T cells (Tregs) and regulatory B cells (Bregs). The role of IL-35 in immunomodulation, antioxidative stress, resistance to apoptosis, control of EC activation, adhesion, and angiogenesis in ECs remains incompletely understood, as the specific mechanisms of IL-35 action and its regulation have yet to be fully elucidated. Therefore, this systematic review aims to comprehensively investigate the impact of IL-35 on ECs and their physiological roles in a range of conditions, including cardiovascular diseases, tumors, sepsis, and rheumatoid arthritis (RA), with the objective of elucidating the potential of IL-35 as a therapeutic target for these ailments.

Thyroid hormone receptor-beta agonist HSK31679 alleviates MASLD by modulating gut microbial sphingolipids

BACKGROUND & AIMS

As the first approved medication for metabolic dysfunction-associated steatohepatitis (MASH), the thyroid hormone receptor-β (THR-β) agonist MGL-3196 (resmetirom) has garnered much attention as a liver-directed, bioactive oral drug. However, studies on MGL-3196 have also identified remarkable heterogeneity of individual clinical efficacy and its interference with gut microbiota in host hepatoenteral circulation remains to be elucidated.

METHODS

We compared MASH attenuation by MGL-3196 and its derivative drug HSK31679 between germ-free (GF) and specific-pathogen free (SPF) mice to evaluate the role of gut microbiota. Then cross-omics analyses of microbial metagenome, metabolome and single-cell RNA-sequencing were applied to a randomized, double-blind, placebo-controlled multiple ascending dose cohort receiving HSK31679 treatment (n = 32) or placebo (n = 8), to comprehensively investigate the altered gut microbiota metabolism and circulating immune signatures.

RESULTS

HSK31679 outperformed MGL-3196 in ameliorating MASH diet-induced steatohepatitis of SPF mice but not GF mice. In the multiple ascending dose cohort of HSK31679, the relative abundance of B. thetaiotaomicron was significantly enriched, impairing glucosylceramide synthase (GCS)-catalyzed monoglucosylation of microbial Cer(d18:1/16:0) and Cer(d18:1/24:1). In contrast to the non-inferior effect of MGL-3196 and HSK31679 on MASH resolution in GFBTΔGCS mice, HSK31679 led to superior benefit on steatohepatitis in GFBTWT mice, due to its steric hindrance of R123 and Y401 of gut microbial GCS. For participants with high fecal GCS activity, the administration of 160 mg HSK31679 induced a shift in peripheral compartments towards an immunosuppressive niche, characterized by decreased CD8α+ dendritic cells and MINCLE+ macrophages.

CONCLUSIONS

This study provided novel insights into the gut microbiota that are key to the efficacy of HSK31679 treatment, revealing microbial GCS as a potential predictive biomarker in MASH, as well as a new target for further microbiota-based treatment strategies for MASH.

IMPACT AND IMPLICATIONS

Remarkable heterogeneity in individual clinical efficacy of thyroid hormone receptor-β agonists and their interferences with the microbiome in host hepatoenteral circulation are poorly understood. In our current germ-free mouse models and a randomized, double-blind, multiple-dose cohort study, we identified microbial glucosylceramide synthase as a key mechanistic node in the resolution of metabolic dysfunction-associated steatohepatitis. Microbial glucosylceramide synthase activity could be a predictive biomarker of response to HSK31679 treatment or a new target for microbiota-based therapeutics in metabolic dysfunction-associated steatohepatitis.

The possible anti-tumor effects of regulatory T cells plasticity / IL-35 in the tumor microenvironment of the major three cancer types

T lymphocytes are among the immunological cells that make up the tumor microenvironment (TME), and they are essential in the growth of tumors and anti-tumor reactions. Regulatory T cells (Treg cells) are a subset of CD4+ T cells in the immune system that suppress the immune system. They are distinguished by their expression of the master transcription factor forkhead box protein P3 (FOXP3). Furthermore, Treg cells are essential for maintaining immunological homeostasis, inhibiting inflammation, and maintaining self-tolerance. In a variety of malignancies within the TME, Treg cells demonstrate notable flexibility and functional diversity. Highly plastic Treg cells can change into Th-like Treg cells in specific circumstances, which allow them to secrete particular pro-inflammatory cytokines. Interleukin 35 (IL-35) is a part of the immunosuppressive cytokines that belong to the IL-12 family. Treg cells release IL-35, which was elevated in the peripheral blood and TME of numerous cancer patients, implying that IL-35 in the TME may be an intriguing target for cancer therapy. In cancer, IL-35 is a two-edged sword; it promotes tumorigenicity in cancer cells while shielding them from apoptosis. Nonetheless, other investigations have mentioned its conflicting effects on cancer prevention. Herein, we provide an updated understanding of the critical mechanisms behind the anticancer immunity mediated by Treg cells plasticity, the role of IL-35, and tactics to strengthen the immune response against malignancies, outlining major clinical trials that used Treg cells/IL-35 therapies in the three main cancer types (lung, breast, and colorectal cancers).

Plasma Interleukin-35 Levels Predict the Prognosis in Patients with HBV-Related Acute-on-Chronic Liver Failure

This study aimed to investigate the impact of IL-35 on the prognosis of patients with HBV-ACLF. We recruited 69 patients with HBV-ACLF, 20 patients with chronic hepatitis B (CHB), 17 patients with liver cirrhosis (LC), and 20 healthy controls (HCs) from a regional infectious disease treatment center in China. Plasma levels of IL-35 at baseline were detected using ELISA. Plasma IL-35 levels in the HBV-ACLF group were the highest among all four groups. Furthermore, survivors exhibited significantly higher IL-35 levels than non-survivors (p < 0.001). IL-35 levels correlated with MELD (r = -0.678, p < 0.001), COSSH-ACLF IIs (r = -0.581, p < 0.001), alpha-fetoprotein (AFP) (r = 0.433, p < 0.001), creatinine (Cr) (r =-0.396, p = 0.001), and lactate (r =-0.38, p =0.001). The combination of plasma IL-35 and MELD score had the highest mortality prediction efficiency, with an area under the curve (AUC) of 0.895 (95% CI: 0.812-0.978, p < 0.001), a sensitivity of 80.6%, and a specificity of 93.9%. Additionally, the Kaplan-Meier analysis revealed that lower levels of IL-35 (≤191.5pg/mL) were associated with poorer survival rates in HBV-ACLF patients (p < 0.001). Our results demonstrated that IL-35 could be an effective predictive marker for the prognosis of HBV-ACLF and improve the predictive performance when combined with the MELD score.

Interleukin-35 alleviates neuropathic pain and induces an anti-inflammatory shift in spinal microglia in nerve-injured male mice

Immune cells are critical in promoting neuroinflammation and neuropathic pain and in facilitating pain resolution, depending on their inflammatory and immunoregulatory cytokine response. Interleukin (IL)-35, secreted by regulatory immune cells, is a member of the IL-12 family with a potent immunosuppressive function. In this study, we investigated the effects of IL-35 on pain behaviors, spinal microglia phenotype following peripheral nerve injury, and in vitro microglial cultures in male and female mice. Intrathecal recombinant IL-35 treatment alleviated mechanical pain hypersensitivity prominently in male mice, with only a modest effect in female mice after sciatic nerve chronic constriction injury (CCI). IL-35 treatment resulted in sex-specific microglial changes following CCI, reducing inflammatory microglial markers and upregulating anti-inflammatory markers in male mice. Spatial transcriptomic analysis revealed that IL-35 suppressed microglial complement activation in the superficial dorsal horn in male mice after CCI. Moreover, in vitro studies showed that IL-35 treatment of cultured inflammatory microglia mitigated their hypertrophied morphology, increased their cell motility, and decreased their phagocytic activity, indicating a phenotypic shift towards homeostatic microglia. Further, IL-35 altered microglial cytokines/chemokines in vitro, suppressing the release of IL-9 and monocyte-chemoattractant protein-1 and increasing IL-10 in the supernatant of male microglial cultures. Our findings indicate that treatment with IL-35 modulates spinal microglia and alleviates neuropathic pain in male mice, suggesting IL-35 as a potential sex-specific targeted immunomodulatory treatment for neuropathic pain.

Structure and assembly of the human IL-12 signaling complex

Interleukin (IL)-12 is a heterodimeric pro-inflammatory cytokine. Our cryoelectron microscopy structure determination of human IL-12 in complex with IL-12Rβ1 and IL-12Rβ2 at a resolution of 3.75 Å reveals that IL-12Rβ2 primarily interacts with the IL-12p35 subunit via its N-terminal Ig-like domain, while IL-12Rβ1 binds to the p40 subunit with its N-terminal fibronectin III domain. This binding mode of IL-12 with its receptors is similar to that of IL-23 but shows notable differences with other cytokines. Through structural information and biochemical assays, we identified Y62, Y189, and K192 as key residues in IL-12p35, which bind to IL-12Rβ2 with high affinity and mediate IL-12 signal transduction. Furthermore, structural comparisons reveal two distinctive conformational states and structural plasticity of the heterodimeric interface in IL-12. As a result, our study advances our understanding of IL-12 signal initiation and opens up new opportunities for the engineering and therapeutic targeting of IL-12.

Extracellular vesicles in fetal-maternal immune tolerance

Two key problems of allo-tolerance during fetal-maternal co-existence are: 1) it's focus must be local, allowing the mother's continued peripheral immune competence to resist pathogens ubiquitously, and 2) it must propagate itself, i.e. continuously recruit new re-enforcements of the local tolerant state. Both are solved by the exosomal pathway of Tregs & Bregs. While the fetal-maternal accomodations of pregnancy terminate at the time of partrurition, geography, climate and the endemic pathogens of the environment surrounding the mother-baby pair would then define the short and long-term effects of their immunologic interaction.

Breakthroughs in road mapping IL-35 mediated immunotherapy for type-1 and autoimmune diabetes mellitus

IL-35 is a recently discovered protein made up of IL-12α and IL-27β chains. It is encoded by IL12A and EBI3 genes. Interest in researching IL-35 has significantly increased in recent years, as evidenced by numerous scientific publications. Diabetes is on the rise globally, causing more illness and death in developing countries. The International Diabetes Federation (IDF) reports that diabetes is increasingly affecting children and teenagers, with varying rates across different regions. Therefore, scientists seek new diabetes treatments despite the growth of drug research. Recent research aims to emphasize IL-35 as a critical regulator of diabetes, especially type 1 and autoimmune diabetes. This review provides an overview of recent research on IL-35 and its link to diabetes and its associated complications. Studies suggest that IL-35 can offer protection against type-1 diabetes and autoimmune diabetes by regulating macrophage polarization, T-cell-related cytokines, and regulatory B cells (Bregs). This review will hopefully assist biomedical scientists in exploring the potential role of IL-35-mediated immunotherapy in treating diabetes. However, further research is necessary to determine the exact mechanism and plan clinical trials.

STAT4 and STAT6, their role in cellular and humoral immunity and in diverse human diseases

Signal transducer and activator of transcription (STAT) 4 and STAT6 play a crucial role in immune cells by transducing signals from specific cytokine receptors, and inducing transcription of genes involved in cell-mediated and humoral immunity. These two different defense mechanisms against pathogens are regulated by two specific CD4+ T helper (Th) cells known as Th1 and Th2 cells. Many studies have shown that several diseases including cancer, inflammatory, autoimmune and allergic diseases are associated with a Th1/Th2 imbalance caused by increased or decreased expression/activity of STAT4 or STAT6 often due to genetic and epigenetic aberrances. An altered expression of STAT4 has been observed in different tumors and autoimmune diseases, while a dysregulation of STAT6 signaling pathway is frequently observed in allergic conditions, such as atopic dermatitis, allergic asthma, food allergy, and tumors such as Hodgkin and non-Hodgkin lymphomas. Recently, dysregulations of STAT4 and STAT6 expression have been observed in SARS-CoV2 and monkeypox infections, which are still public health emergencies in many countries. SARS-CoV-2 can induce an imbalance in Th1 and Th2 responses with a predominant activation of STAT6 in the cytosol and nuclei of pneumocytes that drives Th2 polarization and cytokine storm. In monkeypox infection the virus can promote an immune evasion by inducing a Th2 response that in turn inhibits the Th1 response essential for virus elimination. Furthermore, genetic variations of STAT4 that are associated with an increased risk of developing systemic lupus erythematosus seem to play a role in defense against SARS-CoV-2 infection.

The role of tryptophan metabolism and tolerogenic dendritic cells in maintaining immune tolerance: Insights into celiac disease pathogenesis

BACKGROUND

In mammals, amino acid metabolism has evolved to control immune responses. Tryptophan (Trp) is the rarest essential amino acid found in food and its metabolism has evolved to be a primary regulatory node in the control of immune responses. Celiac disease (CeD) is a developed immunological condition caused by gluten intolerance and is linked to chronic small intestine enteropathy in genetically predisposed individuals. Dendritic cells (DCs), serving as the bridge between innate and adaptive immunities, can influence immunological responses in CeD through phenotypic alterations.

OBJECTIVE

This review aims to highlight the connection between Trp metabolism and tolerogenic DCs, and the significance of this interaction in the pathogenesis of CeD.

RESULTS

It is been recognized that various DC subtypes contribute to the pathogenesis of CeD. Tolerogenic DCs, in particular, are instrumental in inducing immune tolerance, leading to T-reg differentiation that helps maintain intestinal immune tolerance against inflammatory responses in CeD patients and those with other autoimmune disorders. T-regs, a subset of T-cells, play a crucial role in maintaining intestinal immunological homeostasis by regulating the activities of other immune cells. Notably, Trp metabolism, essential for T-reg function, facilitates T-reg differentiation through microbiota-mediated degradation and the kynurenine pathway.

CONCLUSION

Therefore, alterations in Trp metabolism could potentially influence the immune response in CeD, affecting both the development of the disease and the persistence of symptoms despite adherence to a gluten-free diet.

Molecular characterization, expression analysis and function identification of Pf_IL-12p35, Pf_IL-23p19 and Pf_IL-12p40 genes in yellow catfish (Pelteobagrus fulvidraco)

The interleukin-12 (IL-12) family is a class of heterodimeric cytokines that play crucial roles in pro-inflammatory and pro-stimulatory responses. Although some IL-12 and IL-23 paralogues have been found in fish, their functional activity in fish remains poorly understood. In this study, Pf_IL-12p35a/b, Pf_IL-23p19 and Pf_IL-12p40a/b/c genes were cloned from yellow catfish (Pelteobagrus fulvidraco), four α-helices were found in Pf_IL-12p35a/b and Pf_IL-23p19. The transcripts of these six genes were relatively high in mucus and immune tissues of healthy individuals, and in gill leukocytes. Following Edwardsiella ictaluri infection, Pf_IL-12p35a/b and Pf_IL-23p19 mRNAs were induced in brain and kidney (or head kidney), Pf_IL-12p40a mRNA was induced in gill, and Pf_IL-12p40b/c mRNAs were induced in brain and liver (or skin). The mRNA expression of these genes in PBLs was induced by phytohaemagglutinin (PHA) and polyinosinic-polycytidylic acid (poly I:C), while lipopolysaccharides (LPS) induced the mRNA expression of Pf_IL-12p35a and Pf_IL-12p40b/c in PBLs. After stimulation with recombinant (r) Pf_IL-12 and rPf_IL-23 subunit proteins, either alone or in combination, mRNA expression patterns of genes related to T helper cell development exhibited distinct differences. The results suggest that Pf_IL-12 and Pf_IL-23 subunits may play important roles in regulating immune responses to pathogens and T helper cell development.

IL-27 expression regulation and its effects on adaptive immunity against viruses

IL-27, a member of the IL-6/IL-12 cytokine superfamily, is primarily secreted by antigen presenting cells, specifically by dendric cells, macrophages and B cells. IL-27 has antiviral activities and modulates both innate and adaptive immune responses against viruses. The role of IL-27 in the setting of viral infections is not well defined and both pro-inflammatory and anti-inflammatory functions have been described. Here, we discuss the latest advancements in the role of IL-27 in several viral infection models of human disease. We highlight important aspects of IL-27 expression regulation, the critical cell sources at different stages of the infection and their impact in cell mediated immunity. Lastly, we discuss the need to better define the antiviral and modulatory (pro-inflammatory vs anti-inflammatory) properties of IL-27 in the context of human chronic viral infections.

Regulation of Treg cells by cytokine signaling and co-stimulatory molecules

CD4+CD25+Foxp3+ regulatory T cells (Tregs), a vital component of the immune system, are responsible for maintaining immune homeostasis and preventing excessive immune responses. This review explores the signaling pathways of the cytokines that regulate Treg cells, including transforming growth factor beta (TGF-β), interleukin (IL)-2, IL-10, and IL-35, which foster the differentiation and enhance the immunosuppressive capabilities of Tregs. It also examines how, conversely, signals mediated by IL-6 and tumor necrosis factor -alpha (TNF-α) can undermine Treg suppressive functions or even drive their reprogramming into effector T cells. The B7 family comprises indispensable co-stimulators for T cell activation. Among its members, this review focuses on the capacity of CTLA-4 and PD-1 to regulate the differentiation, function, and survival of Tregs. As Tregs play an essential role in maintaining immune homeostasis, their dysfunction contributes to the pathogenesis of autoimmune diseases. This review delves into the potential of employing Treg-based immunotherapy for the treatment of autoimmune diseases, transplant rejection, and cancer. By shedding light on these topics, this article aims to enhance our understanding of the regulation of Tregs by cytokines and their therapeutic potential for various pathological conditions.

Adaptive plasticity of natural interleukin-35-induced regulatory T cells (Tr35) that are required for T-cell immune regulation

Background: IL-35 potently inhibits immune responses both in vivo and in vitro. However, the specific characteristics of IL-35-producing cells, including their developmental origin, cellular phenotype, and function, are unknown. Methods: By using a novel IL-35 reporter mouse (Ebi3-Dre-Thy1.1) and double transgenic fate-mapping reporter mice (35EbiT-Rosa26-rox-tdTomato reporter mice or Foxp3 fate-mapping system), we tracked and analyzed the differentiation and developmental trajectories of Tr35 cells in vivo. And then we investigated the therapeutic effects of OVA-specific Tr35 cells in an OVA-induced allergic airway disease model. Results: We identified a subset of cells, denoted Tr35 cells, that secrete IL-35 but do not express Foxp3. These cells have high expression of molecules associated with T-cell activation and can inhibit T-cell proliferation in vitro. Our analyses showed that Tr35 cells are a distinct subpopulation of cells that are independent of Tr1 cells. Tr35 cells exhibit a unique gene expression profile and tissue distribution. The presence of Thy1.1 (Ebi3) expression in Tr35 cells indicates their active secretion of IL-35. However, the proportion of ex-Tr35 cells (Thy1.1-) is significantly higher compared to Tr35 cells (Thy1.1+). This suggests that Tr35 cells possess the ability to regulate IL-35 expression rapidly in vivo. Tr35 cells downregulated the expression of the inflammatory cytokines IL-4, IFN-γ and IL-17A. However, once Tr35 cells lost IL-35 expression and became exTr35 cells, the expression of inflammatory cytokines was upregulated. Importantly, our findings indicate that Tr35 cells have therapeutic potential. In an OVA-induced allergic airway disease mouse model, Tr35 cell reinfusion significantly reduced airway hyperresponsiveness and histopathological airway and lung inflammation. Conclusions: We have identified a subset of Tregs, Tr35 cells, that are distinct from Tr1 cells. Tr35 cells can dynamically regulate the secretion of inflammatory cytokines by controlling IL-35 expression to regulate inflammatory immune responses.

Regulatory T cell-mediated immunosuppression orchestrated by cancer: towards an immuno-genomic paradigm for precision medicine

Accumulating evidence indicates that aberrant signalling stemming from genetic abnormalities in cancer cells has a fundamental role in their evasion of antitumour immunity. Immune escape mechanisms include enhanced expression of immunosuppressive molecules, such as immune-checkpoint proteins, and the accumulation of immunosuppressive cells, including regulatory T (Treg) cells, in the tumour microenvironment. Therefore, Treg cells are key targets for cancer immunotherapy. Given that therapies targeting molecules predominantly expressed by Treg cells, such as CD25 or GITR, have thus far had limited antitumour efficacy, elucidating how certain characteristics of cancer, particularly genetic abnormalities, influence Treg cells is necessary to develop novel immunotherapeutic strategies. Hence, Treg cell-targeted strategies based on the particular characteristics of cancer in each patient, such as the combination of immune-checkpoint inhibitors with molecularly targeted agents that disrupt the immunosuppressive networks mediating Treg cell recruitment and/or activation, could become a new paradigm of cancer therapy. In this Review, we discuss new insights on the mechanisms by which cancers generate immunosuppressive networks that attenuate antitumour immunity and how these networks confer resistance to cancer immunotherapy, with a focus on Treg cells. These insights lead us to propose the concept of 'immuno-genomic precision medicine' based on specific characteristics of cancer, especially genetic profiles, that correlate with particular mechanisms of tumour immune escape and might, therefore, inform the optimal choice of immunotherapy for individual patients.

Interleukin-12: Structure, Function, and Its Impact in Colorectal Cancer

Interleukin 12 (IL-12) is a heterodimer consisting of 2 subunits, p35 and p40, with unique associations and interacting functions with its family members. IL-12 is one of the most important cytokines regulating the immune system response and is integral to adaptive immunity. IL-12 has shown marked therapeutic potential in a variety of tumor types. This review therefore summarizes the characteristics of IL-12 and its application in tumor treatment, focusing on its antitumor effects in colorectal cancer (CRC) and potential radiosensitization mechanisms. We aim to provide a current reference for IL-12 and other potential CRC treatment strategies.

Tumor-derived interleukin 35 mediates the dissemination of gemcitabine resistance in pancreatic adenocarcinoma

Rapid development of drug resistance after chemotherapy is a major cause of treatment failure in individuals with pancreatic ductal adenocarcinoma (PDAC). In this study, we illustrate that tumor-derived interleukin 35 (IL-35) mediates the accelerated resistance of PDAC to gemcitabine (GEM). We observe that GEM resistance can spread from GEM-resistant PDAC cells to GEM-sensitive cells, and that IL-35 is responsible for the propagation of chemoresistance, which is supported by sequencing and experimental data. Additionally, we discover that GEM-resistant cells have significantly higher levels of IL-35 expression. Mechanistically, aberrantly expressed IL-35 triggers transcriptional activation of SOD2 expression via GP130-STAT1 signaling, scavenging reactive oxygen species (ROS) and leading to GEM resistance. Furthermore, GEM treatment stimulates IL-35 expression through activation of the NF-κB pathway, resulting in acquired chemoresistance. In the mouse model, a neutralizing antibody against IL-35 enhances the tumor suppressive effect of GEM. Collectively, our data suggests that IL-35 is critical in mediating GEM resistance in pancreatic cancer, and therefore could be a valuable therapeutic target in overcoming PDAC chemoresistance.

Decreased Expression of IL-35 and Its Receptor Contributes to Impaired Megakaryopoiesis in the Pathogenesis of Immune Thrombocytopenia

Recent findings have shown that the level of interleukin-35 (IL-35) is abnormal in several autoimmune diseases. Nonetheless, whether IL-35 participates in the pathogenesis of immune thrombocytopenia (ITP) remains unclear. The current study investigates whether IL-35 modulates megakaryopoiesis. The results show that IL-35 receptors are progressively expressed on bone marrow megakaryocytes during the in vitro differentiation of CD34+ progenitors. IL-35 increases the number of megakaryocyte colony-forming units through the Akt pathway. The level of bone marrow IL-35 is reduced in ITP patients, and the decreased level of IL-35 may inhibit megakaryopoiesis. Then, the potential causes of decreased IL-35 in ITP patients are explored. The primary type of cell that secretes IL-35, known as IL-35-producing regulatory T cells (iTr35), is reduced in ITP patients. Bone marrow mesenchymal stem cells (MSCs) from ITP patients exhibit an impaired capability of inducing iTr35 due to enhanced apoptosis, which may contribute to the reduced level of bone marrow IL-35 in ITP patients. Iguratimod promotes megakaryocyte development and differentiation by elevating the expression of IL-35 receptors on megakaryocytes. Iguratimod improves response rates and reduces bleeding symptoms in corticosteroid-resistant ITP patients.

The Role of Interleukin 6 in Periodontitis and Its Complications

Interleukin 6 (IL-6) is a pleomorphic pro-inflammatory cytokine that is strongly associated with local as well as systemic inflammatory processes. Its role in physiological and pathogenic processes throughout the human body has been the subject of numerous studies in recent years. Measurements of the IL-6 levels in gingival crevicular fluid (GFC), as well as in serum, can be important diagnostic and prognostic factors in periodontal diseases (PD) and in assessing their impact on a range of related inflammatory diseases. This narrative review explores the significant role of IL-6 in patients with periodontitis and its association with other widespread inflammatory pathologies.

IL-35: New Target for Immunotherapy Targeting the Tumor Microenvironment

Interleukin 35(IL-35) is a newly discovered inhibitory cytokine of the IL12 family. More recently, IL-35 was found to be increased in the tumor microenvironment (TME) and peripheral blood of many patients with cancer, indicating that it plays an important role in the TME. Tumors secrete cytokines that recruit myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Treg) into the TME to promote malignant progression, which is a great challenge for cancer treatment. Radiotherapy causes serious adverse effects, and tumor resistance to immune checkpoint inhibitors is still an unsolved challenge. Thus, new cancer therapy approaches are urgently needed. Numerous studies have shown that IL-35 can recruit immunosuppressive cells to enable tumor immune escape by promoting the conversion of immune cells into a tumor growth-promoting phenotype as well as facilitating tumor angiogenesis. IL-35-neutralizing antibodies were found to boost the chemotherapeutic effect of gemcitabine and considerably reduce the microvascular density of pancreatic cancer in mice. Therefore, targeting IL-35 in the TME provides a promising cancer treatment target. In addition, IL-35 may be used as an independent prognostic factor for some tumors in the near future. This review intends to reveal the interplay of IL-35 with immune cells in the TME, which may provide new options for the treatment of cancer.

LIF/JAK2/STAT1 Signaling Enhances Production of Galactose-Deficient IgA1 by IgA1-Producing Cell Lines Derived From Tonsils of Patients With IgA Nephropathy

Introduction

Galactose-deficient IgA1 (Gd-IgA1) plays a key role in the pathogenesis of IgA nephropathy (IgAN). Tonsillectomy has been beneficial to some patients with IgAN, possibly due to the removal of tonsillar cytokine-activated cells producing Gd-IgA1. To test this hypothesis, we used immortalized IgA1-producing cell lines derived from tonsils of patients with IgAN or obstructive sleep apnea (OSA) and assessed the effect of leukemia inhibitory factor (LIF) or oncostatin M (OSM) on Gd-IgA1 production.

Methods

Gd-IgA1 production was measured by lectin enzyme-linked immunosorbent assay; JAK-STAT signaling in cultured cells was assessed by immunoblotting of cell lysates; and validated by using small interfering RNA (siRNA) knock-down and small-molecule inhibitors.

Results

IgAN-derived cells produced more Gd-IgA1 than the cells from patients with OSA, and exhibited elevated Gd-IgA1 production in response to LIF, but not OSM. This effect was associated with dysregulated STAT1 phosphorylation, as confirmed by STAT1 siRNA knock-down. JAK2 inhibitor, AZD1480 exhibited a dose-dependent inhibition of the LIF-induced Gd-IgA1 overproduction. Unexpectedly, high concentrations of AZD1480, but only in the presence of LIF, reduced Gd-IgA1 production in the cells derived from patients with IgAN to that of the control cells from patients with OSA. Based on modeling LIF-LIFR-gp130-JAK2 receptor complex, we postulate that LIF binding to LIFR may sequester gp130 and/or JAK2 from other pathways; and when combined with JAK2 inhibition, enables full blockade of the aberrant O-glycosylation pathways in IgAN.

Conclusion

In summary, IgAN cells exhibit LIF-mediated overproduction of Gd-IgA1 due to abnormal signaling. JAK2 inhibitors can counter these LIF-induced effects and block Gd-IgA1 synthesis in IgAN.

The dichotomic role of single cytokines: Fine-tuning immune responses

Cytokines are known for their pleiotropic effects. They can be classified by their function as pro-inflammatory, such as tumor necrosis factor (TNF), interleukin (IL) 1 and IL-12, or anti-inflammatory, like IL-10, IL-35 and transforming growth factor β (TGF-β). Though this type of classification is an important simplification for the understanding of the general cytokine's role, it can be misleading. Here, we discuss recent studies that show a dichotomic role of the so-called pro and anti-inflammatory cytokines, highlighting that their function can be dependent on the microenvironment and their concentrations. Furthermore, we discuss how the back-and-forth interplay between cytokines and immunometabolism can influence the dichotomic role of inflammatory responses as an important target to complement cytokine-based therapies.

Gut microbiota CLA and IL-35 induction in macrophages through Gαq/11-mediated STAT1/4 pathway: an animal-based study

Gut microbiota/metabolites not only participate in the food and energy metabolism but also contribute to the host immune response and homeostasis. The alternation of gut microbiota/metabolites has been widely related to intestinal and extra-intestinal disorders such as intestinal bowel diseases (IBDs). Bactericidal substances from gut epithelial cells can regulate the composition of gut microbiota. However, the effects of regenerating protein 4 (REG4) (human)/(Reg4) (mice), a potentially bactericidal substance from gut epithelial cells, on the gut immune homeostasis maintain elusive. Here, we found that REG4/Reg4 is essential in maintaining gut immune homeostasis through REG4/Reg4 associated gut microbiota. Reg4 knockout (KO) mice were highly sensitive to DSS-mediated colitis, whereas human REG4 intestine epithelial cell transgenic (huREG4IECtg) mice exhibited more resistance to DSS-mediated colitis. Mechanistically, sequencing of gut microbiota and liquid chromatography-mass spectrometry showed that REG4/Reg4 could affect the composition of gut microbiota. REG4/Reg4 associated gut microbiota such as Lactobacillus could metabolize linoleic acid (LA) into conjugated linoleic acid (CLA). Immunoprecipitation and immunoblot showed that CLA could effectively promote the expression of IL-35 in macrophages through Gαq/11 mediated activation STAT1/4. Thus, our results demonstrate that REG4/Reg4 plays a critical role in maintaining gut immune homeostasis through CLA-mediated IL-35+ macrophages.

IL-35 Stabilizes Treg Phenotype to Protect Cardiac Allografts in Mice

BACKGROUND

Interleukin-35 (IL-35), secreted by regulatory T cells (Treg) and B cells, is immunosuppressive under both physiological and pathological conditions. However, the role of IL-35 in all responses has yet to be investigated. Here, we demonstrate that IL-35 protects allografts by stabilizing the Treg phenotype and suppressing CD8 + T-cell activation in a mouse heart transplantation model.

METHODS

The effect of IL-35 on immune cell infiltration in grafts and secondary lymphoid organs was examined using mass cytometry, flow cytometry, and immunofluorescence. Moreover, using quantitative real-time polymerase chain reaction, flow cytometry, and phospho-flow assays, we demonstrated that IL-35 maintains Treg phenotypes to restrain CD8 + T cells via the gp130/signal transducer and activator of transcription 1 pathway.

RESULTS

Mass cytometry analysis of intragraft immune cells showed that IL-35 decreased CD8 + T-cell infiltration and increased Foxp3 and IL-35 expressions in Treg. In vitro, we demonstrated that IL-35 directly promoted Treg phenotypic and functional stability and its IL-35 secretion, generating a positive feedback loop. However, Treg are required for IL-35 to exert its suppressive effect on CD8 + T cells in vitro. After depleting Treg in the recipient, IL-35 did not prolong graft survival or decrease CD8 + T-cell infiltration. Mechanistically, we found that IL-35 sustained Treg stability via the gp130/signal transducer and activator of transcription 1 signaling pathway.

CONCLUSIONS

Our findings highlight that IL-35 stabilizes the Treg phenotype to ameliorate CD8 + T-cell infiltration in the allograft, which has never been described in the transplanted immunological milieu.

A dual-role for IL-10: From leukemogenesis to the tumor progression in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer in the world, and accounts for 25% of all childhood cancers among children under 15 years of age. Longitudinal studies have shown that children with ALL are born with a deregulated immune response that, together with postnatal environmental exposures, favor the onset of the disease. In this context, IL-10, a key cytokine in the regulation of the immune response, presents itself as a paradoxical mediator, initially influencing the development of ALL through the regulation of inflammatory processes and later on the progression of malignancy, with the increase of this molecule in the leukemia microenvironment. According to the literature, this cytokine plays a critical role in the natural history of the disease and plays an important role in two different though complex scenarios. Thus, in this review, we explore the dual role of IL-10 in ALL, and describe its biological characteristics, immunological mechanisms and genetics, as well as its impact on the leukemia microenvironment and its clinical implications.

Regulatory B cells induced by interleukin-35 inhibit inflammation and alveolar bone resorption in ligature-induced periodontitis

BACKGROUND

Regulatory B cells (Bregs) have been reported to suppress immune responses and alveolar bone loss in murine periodontitis models. These cells could be induced by interleukin (IL)-35 which is increased upon periodontal inflammation. Thus, this study aimed to explore the role of Bregs induced by IL-35 in periodontitis.

METHODS

Experimental periodontitis was induced in mice by ligature. Two weeks after ligation, the test group was systemically treated with IL-35 for 1 week. Four weeks after ligation, all mice were euthanized, and alveolar bone loss was evaluated by microcomputed tomography. Cytokines associated with periodontitis were analyzed using reverse transcription-quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Bregs in spleens, cervical lymph nodes, and periodontal tissues were detected by flow cytometry and immunofluorescence staining.

RESULTS

In the mouse model of periodontitis, IL-35 induced the expansion of CD1dhi CD5+ B10 cells with increased interleukin-10 (IL-10) and IL-35 production. IL-35 administration also attenuated alveolar bone loss and reduced the levels of proinflammatory cytokines in situ.

CONCLUSIONS

Following ligature-induced periodontitis in mice, IL-35 inhibited periodontal inflammation and alveolar bone resorption at least partially through the induction of B10 cells and IL-35+ Bregs.

Human interleukin-12α and EBI3 are cytokines with anti-inflammatory functions

Interleukins are secreted proteins that regulate immune responses. Among these, the interleukin 12 (IL-12) family holds a central position in inflammatory and infectious diseases. Each family member consists of an α and a β subunit that together form a composite cytokine. Within the IL-12 family, IL-35 remains particularly ill-characterized on a molecular level despite its key role in autoimmune diseases and cancer. Here we show that both IL-35 subunits, IL-12α and EBI3, mutually promote their secretion from cells but are not necessarily secreted as a heterodimer. Our data demonstrate that IL-12α and EBI3 are stable proteins in isolation that act as anti-inflammatory molecules. Both reduce secretion of proinflammatory cytokines and induce the development of regulatory T cells. Together, our study reveals IL-12α and EBI3, the subunits of IL-35, to be functionally active anti-inflammatory immune molecules on their own. This extends our understanding of the human cytokine repertoire as a basis for immunotherapeutic approaches.

The Relationship between TNF-a, IL-35, VEGF and Cutaneous Microvascular Dysfunction in Young Patients with Uncomplicated Type 1 Diabetes

The aim of this study was to analyze the relationship between immunological markers and the dysfunction of cutaneous microcirculation in young patients with type 1 diabetes. The study group consisted of 46 young patients with type 1 diabetes and no associated complications. Microvascular function was assessed with the use of nail fold capillaroscopy before and after implementing post-occlusive reactive hyperemia. This evaluation was then repeated after 12 months. Patients were divided into two subgroups according to their baseline median coverage (defined as the ratio of capillary surface area to surface area of the image area), which was established during the initial exam (coverageBASE). Additionally, the levels of several serum biomarkers, including VEGF, TNF-a and IL-35, were assessed at the time of the initial examination. HbA1c levels obtained at baseline and after a 12-month interval were also obtained. Mean HbA1c levels obtained during the first two years of the course of the disease were also analyzed. Patients with coverageBASE below 16.85% were found to have higher levels of VEGF and TNF-α, as well as higher levels of HbA1c during the first two years following diabetes diagnosis. Our results support the hypothesis that the development of diabetic complications is strongly influenced by metabolic memory and an imbalance of pro- and anti-inflammatory cytokines, regardless of achieving adequate glycemic control.

The role of iTr35 cells in the inflammatory response and fibrosis progression of systemic sclerosis

OBJECTIVE

To evaluate the role of induced immunosuppressive T regulatory (iTr) 35 cells in SSc-related inflammation and fibrosis.

METHODS

Sixty-eight SSc patients were enrolled in this study. Subsets of iTr35 and Tr1 were measured by flow cytometry. IL-35 and IL-10 levels were measured using ELISA. Expressions of iTr35, Tr1, fibrosis-related genes and proteins associated with signalling pathways were determined using immunofluorescence, western blot and immunohistochemistry assays.

RESULTS

In peripheral blood, the proportions of the iTr35 cells were higher and Tr1 cells were lower than the control group. Similarly, IL-35 expression was increased, while IL-10 levels were decreased. In fibroblasts from skin tissue, the expression levels of EBI3, IL-12Ap35, Foxp3 and IL-10 were decreased, but collagen I, TGF-β, alpha smooth muscle actin (α-SMA) and fibronectin levels were increased. Phosphorylated STAT3/6 were increased, but iTr35 and Tr1 cell levels were significantly decreased. When CD4+ cells were incubated with both recombinant human (rh)IL-35 and rhIL-10, the cell numbers of iTr35 and Tr1 were greater than the same type of cells treated with rhIL-35 or rhIL-10 alone. However, the viability of conventional CD4+ T cells was decreased by gradually increasing iTr35 cells. Moreover, iTr35 cells affected α-SMA expression through the STAT3/6 signalling pathway.

CONCLUSION

Both iTr35 and Tr1 cells are involved in SSc-related inflammation and fibrosis. IL-35 can induce iTr35 cells, showing a synergistic effect with IL-10. We also found that iTr35 cells can inhibit T cell proliferation and differentiation via the STAT3/6 signalling pathway, thereby causing fibrosis.

Ebi3 knockout aggravates experimental periodontitis via Th17 polarization

AIM

To investigate the role of Ebi3-related cytokines (i.e., interleukin [IL]-35 and/or IL-27) in experimental periodontitis using Ebi3 knockout (KO) mice.

MATERIALS AND METHODS

The maxillary right second molar teeth of Ebi3 KO mice and C57BL/6 mice were tied with a silk ligature to induce periodontitis. Three days after ligation, gingival tissues were collected for gene expression analyses. Five days after ligation, the maxillae were removed for haematoxylin and eosin staining and immunohistochemistry. Seven days after ligation, the maxillae were removed for micro-computed tomography.

RESULTS

The ligated side of Ebi3 KO mice showed intense alveolar bone resorption, which was substantially more pronounced than in wild-type (WT) mice. IL-17A expression was significantly higher in the gingiva of the ligated side of Ebi3 KO mice compared with WT mice. IL-10 expression was significantly lower in Ebi3 KO mice than in WT mice. The ligature-induced alveolar bone resorption in Ebi3 KO mice that received recombinant IL-35 injection was significantly less compared with that in Ebi3 KO mice that received control injection.

CONCLUSIONS

Together, these findings suggest that Th17 cells exacerbate experimental periodontitis in mice lacking Ebi3 and that IL-35 may play a critical role in inhibiting periodontal tissue destruction.

A20 is a master switch of IL-33 signaling in macrophages and determines IL-33-induced lung immunity

BACKGROUND

IL-33 plays a major role in the pathogenesis of allergic diseases such as asthma and atopic dermatitis. On its release from lung epithelial cells, IL-33 primarily drives type 2 immune responses, accompanied by eosinophilia and robust production of IL-4, IL-5, and IL-13. However, several studies show that IL-33 can also drive a type 1 immune response.

OBJECTIVE

We sought to determine the role of A20 in the regulation of IL-33 signaling in macrophages and IL-33-induced lung immunity.

METHODS

We studied the immunologic response in lungs of IL-33-treated mice that specifically lack A20 in myeloid cells. We also analyzed IL-33 signaling in A20-deficient bone marrow-derived macrophages.

RESULTS

IL-33-induced lung innate lymphoid cell type 2 expansion, type 2 cytokine production, and eosinophilia were drastically reduced in the absence of macrophage A20 expression, whereas neutrophils and interstitial macrophages in lungs were increased. In vitro, IL-33-mediated nuclear factor kappa B activation was only weakly affected in A20-deficient macrophages. However, in the absence of A20, IL-33 gained the ability to activate signal transducer and activator of transcription 1 (STAT1) signaling and STAT1-dependent gene expression. Surprisingly, A20-deficient macrophages produced IFN-γ in response to IL-33, which was fully STAT1-dependent. Furthermore, STAT1 deficiency partially restored the ability of IL-33 to induce ILC2 expansion and eosinophilia in myeloid cell-specific A20 knockout mice.

CONCLUSIONS

We reveal a novel role for A20 as a negative regulator of IL-33-induced STAT1 signaling and IFN-γ production in macrophages, which determines lung immune responses.

Human IL-35 Inhibits the Bioactivity of IL-12 and Its Interaction with IL-12Rβ2

IL-35 is an immunosuppressive cytokine with roles in cancer, autoimmunity, and infectious disease. In the conventional model of IL-35 biology, the p35 and Ebi3 domains of this cytokine interact with IL-12Rβ2 and gp130, respectively, on the cell surface of regulatory T and regulatory B cells, triggering their suppression of Th cell activity. Here we use a human IL-12 bioactivity reporter cell line, protein binding assays, and primary human Th cells to demonstrate an additional mechanism by which IL-35 suppresses Th cell activity, wherein IL-35 directly inhibits the association of IL-12 with its surface receptor IL-12Rβ2 and downstream IL-12-dependent activities. IL-12 binding to the surface receptor IL-12Rβ1 was unaffected by IL-35. These data demonstrate that in addition to acting via regulatory T and regulatory B cells, human IL-35 can also directly suppress IL-12 bioactivity and its interaction with IL-12Rβ2.

Potential of Interleukin (IL)-12 Group as Antivirals: Severe Viral Disease Prevention and Management

The interleukin (IL)-12 family consists of pro- and anti-inflammatory cytokines that are able to signal the activation of host antiviral immunity while preventing over-reactive immune reactions due to active virus replication and viral clearance. Amongst others, IL-12 and IL-23 are produced and released by innate immune cells such as monocytes and macrophages to signal the proliferation of T cells and release of effector cytokines, which subsequently activate host defence against virus infections. Interestingly, the dualities of IL-27 and -35 are evidently shown in the course of virus infections; they regulate the synthesis of cytokines and antiviral molecules, proliferation of T cells, and viral antigen presentation in order to maximize virus clearance by the host immune system. In terms of anti-inflammatory reactions, IL-27 signals the formation of regulatory T cells (Treg) which in turn secrete IL-35 to control the scale of inflammatory response that takes place during virus infections. Given the multitasking of the IL-12 family in regards to the elimination of virus infections, its potential in antiviral therapy is unequivocally important. Thus, this work aims to delve deeper into the antiviral actions of the IL-12 family and their applications in antiviral therapies.

Interleukin-35 Enhances Regulatory T Cell Function by Potentially Suppressing Their Transdifferentiation into a T Helper 17-Like Phenotype in Kawasaki Disease

Interleukin-35 (IL-35) modulates immune cell activity in inflammation and autoimmune disorders. However, its specific effects on regulatory T cells (Tregs) in Kawasaki disease remain ambiguous. We enrolled 37 patients with Kawasaki disease and 20 healthy controls in this study. The percentages of CD4⁺CD25⁺CD127^dim/- Tregs and CD4⁺IL-17A⁺ T helper 17 (Th17) cells were determined via flow cytometry. Tregs were enriched and stimulated by recombinant IL-35. Immunosuppressive activity of Tregs was via co-culture with autologous CD4⁺CD25^- T cells. Purified Tregs were cultured for Th17 polarization, and the influence of IL-35 on Tregs transdifferentiation into a Th17-like phenotype was determined. The percentage of Tregs was elevated in patients with Kawasaki disease and positively correlated with C-reactive protein levels. There was no significant difference in the percentage of Th17 cells between the two groups. IL-35 stimulation increased the percentage of Tregs in both groups, but decreased the percentage of Tregs Th17 cells in affected patients. IL-35 enhanced the immunosuppressive activity of Tregs in both groups, resulting in decreased cellular proliferation and increased IL-35 subunit mRNA relative levels in co-culture system. IL-35 did not affect the immune checkpoint molecule expression in Tregs, but inhibited the transdifferentiation of Tregs into a Th17-like phenotype in affected patients, indicating by the down-regulations of C-C motif chemokine receptor-4/6 expression, retinoid-related orphan nuclear receptor γt mRNA levels, and IL-17 secretion. IL-35 contributes to the immunosuppressive function of Tregs by inhibiting the cellular proliferation and transdifferentiation of Tregs into a Th17-like phenotype, which may be a protective mechanism against Kawasaki disease.

Interleukin-35 and Interleukin-37 anti-inflammatory effect on inflammatory bowel disease: Application of non-coding RNAs in IBD therapy

Inflammatory bowel disease (IBD) is a widespread autoimmune disease that may even be life-threatening. IBD is divided into two major subtypes: ulcerative colitis and Crohn's disease. Interleukin (IL)-35 and IL-37 are anti-inflammatory cytokines that belong to IL-12 and IL-1 families, respectively. Their recruitment relieves inflammation in various autoimmune diseases, including psoriasis, multiple sclerosis, rheumatoid arthritis, and IBD. Regulatory T cells (Tregs) and regulatory B cells (Bregs) are the primary producers of IL-35/IL-37. IL-35 and IL-37 orchestrate the regulation of the immune system through two main strategies: Blocking nuclear transcription factor kappa-B (NF-kB) and mitogen-activated protein kinase (MAPK) signaling pathways or promoting the proliferation of Tregs and Bregs. Moreover, IL-35 and IL-37 can also inhibit inflammation by adjusting the T helper (Th)17/Treg ratio balance. Among the anti-inflammatory cytokines, IL-35 and IL-37 have significant potential to reduce intestinal inflammation. Therefore, administering IL-35/IL-37-based drugs or blocking their inhibitor microRNAs could be a promising approach to alleviate IBD symptoms. Overall, in this review article, we summarized the therapeutic application of IL-35 and IL-37 in both human and experimental models of IBD. Also, it is hoped that this practical information will reach beyond IBD therapy and shed some light on treating all intestinal inflammations.

Interleukin-35 -producing B cells rescues inflammatory bowel disease in a mouse model via STAT3 phosphorylation and intestinal microbiota modification

Interleukin-35 (IL-35)-producing B cells (IL-35⁺B cells) play an important role in diseases, and the expansion of IL-35⁺ immune cells have been observed in inflammatory bowel disease (IBD). However, how IL-35⁺B cells function and the manner in which they perform their roles remain unclear. In this study, human samples and animal models were used to confirm the expansion of IL-35⁺B cells during IBD. In addition, by using il12a^-/- and ebi3^-/- mice, we demonstrated that the regulatory role of B cells in IBD depends on IL-35. Mechanically, IL-35⁺B cells can promote its own expansion through endocrine actions and depend on the transcription factor signal transducer and activator of transcription 3. Interestingly, we found that the diversity of intestinal microbes and expression of microbial metabolites decreased during IBD. IL-35⁺B cells promote the high expression of indoleacetic acid (IAA), and exogenous metabolite supplementation with IAA can further promote the expansion of IL-35⁺B cells and rescues the disease. This study provides a new concept for the regulatory model of B cells and a new approach for the treatment of IBD.

INTERLEUKIN-35 DOWNREGULATES THE IMMUNE RESPONSE OF EFFECTOR CD4 + T CELLS VIA RESTRICTING HIGH MOBILITY GROUP BOX-1 PROTEIN-DEPENDENT AUTOPHAGY IN SEPSIS

ABSTRACT

Background: Immunosuppression is critically involved in the development of sepsis and is closely associated with poor outcomes. The novel role of the anti-inflammatory cytokine IL-35 in sepsis was examined. Methods: Sepsis was induced by in C57BL/6 mice cecal ligation and puncture (CLP). The impacts of IL-35 on effector CD4 + T cells were investigated by examining cell proliferation and the Th1/Th2 ratio in the presence of recombinant IL-35 (rIL-35) or anti-IL-35 (EBI3). The regulatory effect of IL-35 on autophagy was evaluated by measuring autophagy markers and autophagic flux in CLP mice in vivo and in activated effector CD4 + T cells in vitro . Results: IL-35 levels were significantly increased in the serum and spleens of septic mice. rIL-35 administration after CLP further decreased proliferation and the Th1/Th2 ratio in effector CD4 + T cells and significantly shortened the survival time. Sepsis-induced autophagy activation was protective in effector CD4 + T cells and was blocked by rIL-35. The inhibitory effect of IL-35 on autophagy was observed in activated effector CD4 + T cells in vitro , and this effect was mediated by restricting high mobility group box-1 protein (HMGB1) translocation. Conclusion: IL-35 is an immunosuppressive cytokine that impairs CD4 + T-cell proliferation and differentiation in sepsis, and the effect might be mediated by reducing HMGB1-dependent autophagy.

Interleukin-35 dampens T helper 22 phenotype shift in CD4+CD25+CD127dim/- regulatory T cells in primary biliary cholangitis

The phenotype shift in regulatory T cells (Tregs) contributes to immunopathogenesis of autoimmune diseases. The current study was aimed to investigate the regulatory function of interleukin-35 (IL-35) to T helper 22 (Th22) cell phenotype shift in Tregs in primary biliary cholangitis (PBC). Fifty-five PBC patients and twenty-four controls were enrolled. CD4+CD25+CD127dim/- Tregs and Th22 cells were investigated by flow cytometry. Forkhead box P3 (FoxP3) and aryl hydrocarbon receptor (AhR) mRNA levels were assessed by real-time polymerase chain reaction. Plasma IL-10 and IL-22 levels were measured by ELISA. Purified Tregs were stimulated with exogenous IL-35, and were co-cultured with autologous CD4+CD25- T cells. Cellular proliferation and cytokine production was measured. Purified Tregs were also cultured into Th22 condition in the presence or absence of exogenous IL-35, and Th22 phenotype were assessed. PBC patients had lower levels of Treg percentage, FoxP3 mRNA, and plasma IL-10, while had higher levels of Th22 proportion, AhR mRNA, and plasma IL-22. Tregs from PBC patients showed reduced immunosuppressive activity, which presented as increased cellular proliferation, interferon-γ production and decreased IL-35/IL-10 secretion in co-culture system. Tregs shifted into Th22 phenotype in PBC patients with elevated CCR4, CCR6, and CCR10 expression as well as increased IL-22 production. IL-35 not only enhanced inhibitory function of Tregs but also suppressed phenotype shift of Tregs into Th22 phenotype in PBC patients. This process was accompanied by elevation of IL-10 and transforming growth factor-β1 secretion by Tregs from PBC patients. The present data suggested that reduced IL-35 might be insufficient to maintain Tregs function and phenotype shift from Tregs into Th22 phenotype in PBC patients.

Current Insight into the Role of IL-35 and Its Potential Involvement in the Pathogenesis and Therapy of Atopic Dermatitis

Interleukin 35 (IL-35), a new member of the IL-12 family of heterodimeric cytokines, could induce two different types of regulatory cells including regulatory T and B cells such as IL-35-induced regulatory T cells and IL-10-producing regulatory B cells (IL-10+Bregs), and IL-35-producing regulatory B cells (IL-35+Bregs). These cells appear to play an important role in modulating the immune system in numerous diseases. Several findings suggested that the expression of IL-35 is dysregulated in many autoimmune, inflammatory, and allergic diseases. Due to the functions of IL-35, it seems that this cytokine may act as an efficient therapeutic strategy for numerous conditions including atopic dermatitis (AD). We aimed to provide a comprehensive overview of the role of IL-35 in modulating the immune system. Additionally, we highlight IL-35 as a specific immunological target, discuss its possible involvement in the pathogenesis of AD, and hypothesize that IL-35 may become a novel target for the treatment of AD. However, further studies are required to evaluate this hypothesis.

Therapeutic targeting of regulatory T cells in cancer

The success of immunotherapy in oncology underscores the vital role of the immune system in cancer development. Regulatory T cells (Tregs) maintain a fine balance between autoimmunity and immune suppression. They have multiple roles in the tumor microenvironment (TME) but act particularly in suppressing T cell activation. This review focuses on the detrimental and sometimes beneficial roles of Tregs in tumors, our current understanding of recruitment and stabilization of Tregs within the TME, and current Treg-targeted therapeutics. Research identifying subpopulations of Tregs and their respective functions and interactions within the complex networks of the TME will be crucial to develop the next generation of immunotherapies. Through these advances, Treg-targeted immunotherapy could have important implications for the future of oncology.