Distinctive expression of interleukin‐23 receptor subunits on human Th17 and γδ T cells

Interleukin 23 receptor: Expression and regulation in immune cells

The importance of IL-23 and its specific receptor, IL-23R, in the pathogenesis of several chronic inflammatory diseases has been established, but the underlying pathological mechanisms are not fully understood. This review focuses on IL-23R expression and regulation in immune cells.

Deciphering the Genetic Code of Autoimmune Kidney Diseases

Autoimmune kidney diseases occur due to the loss of tolerance to self-antigens, resulting in inflammation and pathological damage to the kidneys. This review focuses on the known genetic associations of the major autoimmune kidney diseases that result in the development of glomerulonephritis: lupus nephritis (LN), anti-neutrophil cytoplasmic associated vasculitis (AAV), anti-glomerular basement disease (also known as Goodpasture's disease), IgA nephropathy (IgAN), and membranous nephritis (MN). Genetic associations with an increased risk of disease are not only associated with polymorphisms in the human leukocyte antigen (HLA) II region, which governs underlying processes in the development of autoimmunity, but are also associated with genes regulating inflammation, such as NFkB, IRF4, and FC γ receptors (FCGR). Critical genome-wide association studies are discussed both to reveal similarities in gene polymorphisms between autoimmune kidney diseases and to explicate differential risks in different ethnicities. Lastly, we review the role of neutrophil extracellular traps, critical inducers of inflammation in LN, AAV, and anti-GBM disease, where inefficient clearance due to polymorphisms in DNase I and genes that regulate neutrophil extracellular trap production are associated with autoimmune kidney diseases.

Fc Binding by FcγRIIa Is Essential for Cellular Activation by the Anti-FcγRIIa mAbs 8.26 and 8.2

FcγR activity underpins the role of antibodies in both protective immunity and auto-immunity and importantly, the therapeutic activity of many monoclonal antibody therapies. Some monoclonal anti-FcγR antibodies activate their receptors, but the properties required for cell activation are not well defined. Here we examined activation of the most widely expressed human FcγR; FcγRIIa, by two non-blocking, mAbs, 8.26 and 8.2. Crosslinking of FcγRIIa by the mAb F(ab’)₂ regions alone was insufficient for activation, indicating activation also required receptor engagement by the Fc region. Similarly, when mutant receptors were inactivated in the Fc binding site, so that intact mAb was only able to engage receptors via its two Fab regions, again activation did not occur. Mutation of FcγRIIa in the epitope recognized by the agonist mAbs, completely abrogated the activity of mAb 8.26, but mAb 8.2 activity was only partially inhibited indicating differences in receptor recognition by these mAbs. FcγRIIa inactivated in the Fc binding site was next co-expressed with the FcγRIIa mutated in the epitope recognized by the Fab so that each mAb 8.26 molecule can contribute only three interactions, each with separate receptors, one via the Fc and two via the Fab regions. When the Fab and Fc binding were thus segregated onto different receptor molecules receptor activation by intact mAb did not occur. Thus, receptor activation requires mAb 8.26 Fab and Fc interaction simultaneously with the same receptor molecules. Establishing the molecular nature of FcγR engagement required for cell activation may inform the optimal design of therapeutic mAbs.

High CD26 and Low CD94 Expression Identifies an IL-23 Responsive Vδ2+ T Cell Subset with a MAIT Cell-like Transcriptional Profile

Vδ2⁺ T cells play a critical role in immunity to micro-organisms and cancer but exhibit substantial heterogeneity in humans. Here, we demonstrate that CD26 and CD94 define transcriptionally, phenotypically, and functionally distinct Vδ2⁺ T cell subsets. Despite distinct antigen specificities, CD26^hiCD94^lo Vδ2⁺ cells exhibit substantial similarities to CD26^hi mucosal-associated invariant T (MAIT) cells, although CD26^- Vδ2⁺ cells exhibit cytotoxic, effector-like profiles. At birth, the Vδ2⁺Vγ9⁺ population is dominated by CD26^hiCD94^lo cells; during adolescence and adulthood, Vδ2⁺ cells acquire CD94/NKG2A expression and the relative frequency of the CD26^hiCD94^lo subset declines. Critically, exposure of the CD26^hiCD94^lo subset to phosphoantigen in the context of interleukin-23 (IL-23) and CD26 engagement drives the acquisition of a cytotoxic program and concurrent loss of the MAIT cell-like phenotype. The ability to modulate the cytotoxic potential of CD26^hiCD94^lo Vδ2⁺ cells, combined with their adenosine-binding capacity, may make them ideal targets for immunotherapeutic expansion and adoptive transfer.

An emerging role of interleukin-23 in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune, chronic inflammatory disease and is characterized by destruction of the articular cartilage. A number of pro-inflammatory cytokines work sequentially and in concert with one another to induce the development of RA. IL-23, a member of IL-12 family, is composed of p19 and p40 subunits and it interacts with IL-23 receptor complex to trigger plethora of biochemical actions. A number of preclinical studies have shown the role of IL-23 in the development of RA in rodents. IL-23 receptor signaling is primarily linked to the activation of JAK-STAT, tyrosine kinase 2, NF-kB, and retinoic acid receptor-related orphan receptors. IL-23 produces its osteoclastogenic effects, mainly through IL-17 and Th17 cells suggesting the importance of IL-23/IL-17/Th17 in the joint inflammation and destruction in RA. Monoclonal antibodies targeted against IL-23, including tildrakizumab and guselkumab have been developed and evaluated in clinical trials. However, there are very limited clinical studies regarding the use of IL-23 modulators in RA patients. The present review discusses the different aspects of IL-23 including its structural features, signal transduction pathway, preclinical, and clinical role in RA.

AS2762900-00, a potent anti-human IL-23 receptor monoclonal antibody, prevents epidermal hyperplasia in a psoriatic human skin xenograft model

Interleukin (IL)-23 is thought to be critical in the pathogenesis of psoriasis, and anti-IL-23 monoclonal antibodies (mAbs) have been approved for the treatment of psoriasis. We speculated that an anti-IL-23 receptor mAb might have greater efficacy than an anti-IL-23 mAb in the treatment of local inflamed lesions with high IL-23 levels. We previously generated an anti-human IL-23 receptor mAb, AS2762900-00, which potently blocked IL-23-induced cell proliferation, regardless of the concentration of IL-23. Here, we evaluated the therapeutic potential of AS2762900-00 in the treatment of psoriasis. Compared with untreated control, AS2762900-00 significantly reduced the epidermal thickness of lesions in a clinically relevant psoriatic human skin xenograft model. The expression of inflammatory genes including genes downstream of IL-23 signaling in the lesion tended to be lower in the AS2762900-00 group than the untreated group, suggesting that the inhibitory effects of AS2762900-00 in the psoriatic human skin xenograft model might occur via blockade of IL-23 signaling pathways. Further, AS2762900-00 showed an inhibitory effect on signal transducer and activator of transcription 3 (STAT3) phosphorylation as a downstream signal of IL-23 receptor activation in whole blood from patients with psoriasis. We also confirmed that AS2762900-00 inhibited IL-23-induced STAT3 phosphorylation in a concentration-dependent manner using whole blood from healthy donors. These data suggest that AS2762900-00 is a promising drug candidate for the treatment of psoriasis. In addition, STAT3 phosphorylation in whole blood may be a useful biomarker for the evaluation of the pharmacodynamic effects of AS2762900-00 in healthy volunteers in clinical development.

The Human IL-23 Decoy Receptor Inhibits T-Cells Producing IL-17 by Genetically Engineered Mesenchymal Stem Cells

The immunomodulatory and self-renewable features of human adipose mesenchymal stem cells (hAD-MSCs) mark their importance in regenerative medicine. Interleukin 23 (IL- 23) as a proinflammatory cytokine suppresses T regulatory cells (Treg) and promotes the response of T helper 17 (Th17) and T helper 1 (Th1) cells. This pathway starts inflammation and immunosuppression in several autoimmune diseases. The current study for producing recombinant IL- 23 decoy receptor (RIL- 23R) using hAD-MSCs as a good candidate for ex vivo cell-based gene therapy purposes reducing inflammation in autoimmune diseases. hAD-MSCs was isolated from lipoaspirate and then characterized by differentiation. RIL- 23R was designed and cloned into a pCDH-813A- 1 lentiviral vector. The transduction of hAD-MSCs was performed at MOI (multiplicity of infection) = 50 with pCDH- EFI α- RIL- 23R- PGK copGFP. Expressions of RIL- 23R and octamer-binding transcription factor 4 (OCT- 4) were determined by real-time polymerase chain reaction (real time-PCR). Self-renewing properties were assayed with OCT- 4. Bioactivity of the designed RIL- 23R was evaluated by IL- 17 and IL- 10 expression of mouse splenocytes. Cell differentiation confirmed the true isolation of hAD-MSCs from lipoaspirate. Restriction of the enzyme digestion and sequencing verified the successful cloning of RIL- 23R in the CD813A-1 lentiviral vector. The green fluorescent protein (GFP) positive transduction rate was up to 90%, and real-time PCR showed the expression level of RIL-23R. Oct-4 had a similar expression pattern with nontransduced hAD-MSCs and transduced hAD-MSCs/ RIL-23R indicating that lentiviral vector did not affect hAD-MSCs characteristics. Downregulation of IL-17 and upregulation of IL-10 showed the correct activity of the engineered hAD-MSCs. The results showed that the transduced hAD-MSCs/ RIL- 23R, expressing IL-23 decoy receptor, can give a useful approach for a basic research on cell-based gene therapy for autoimmune disorders.

Genetically Engineered Adipose Mesenchymal Stem Cells Using HIV-Based Lentiviral Vectors as Gene Therapy for Autoimmune Diseases

The immunomodulatory and self-renewable features of human adipose-derived mesenchymal stem cells (hAD-MSCs) mark their importance in regenerative medicine. Interleukin (IL)-23 as a proinflammatory cytokine suppresses T regulatory cells and promotes the response of T helper 17 and T helper 1 cells. This pathway initiates inflammation and immunosuppression in several autoimmune diseases. The current study aimed at producing recombinant IL-23 decoy receptor (RIL-23R) using hAD-MSCs as a good candidate for ex vivo cell-based gene therapy purposes to reduce inflammation in autoimmune diseases. hAD-MSCs was isolated from lipoaspirate and then characterized by differentiation. RIL-23R was designed and cloned into a pCDH813A-1 lentiviral vector. The transduction of hAD-MSCs was performed at multiplicity of infection = 50 with pCDH-EFI α-RIL-23R-PGK copGFP. Expressions of RIL-23R and octamer-binding transcription factor 4 (OCT-4) were determined by real-time polymerase chain reaction. Self-renewing properties were assayed with OCT-4. Bioactivity of the designed RIL-23R was evaluated by IL-17 and IL-10 expression of mouse splenocytes. The results showed that the transducted hAD-MSCs/RIL-23R, expressing IL-23 decoy receptor, can provide a useful approach for a basic research on cell-based gene therapy for autoimmune disorders.

Developmental endothelial locus-1 (Del-1) antagonizes Interleukin-17-mediated allergic asthma

Interleukin (IL)-17 is a major contributor to the pathogenesis of allergic asthma. Developmental endothelial locus-1 (Del-1) is an endothelial cell-secreted protein known to inhibit IL-17 expression. However, little is known about the association between Del-1 and IL-17 in the pathogenesis of allergic asthma. Using bronchoalveolar lavage fluid (BALF) and peripheral blood samples collected from allergic asthmatic patients and controls, we explored the role of Del-1 in relation to IL-17 in allergic asthma. We found that the negative correlation between Del-1 and IL-17 was significant in BALF of allergic asthmatics. Del-1 treatment inhibited the expression of IL-17, the differentiation of IL-17-secreting leukocytes and associated cytokines. Contrarily, IL-17 levels were increased after treatment with anti-Del-1 mAb. Consistent with this, Del-1 treatment led to downregulation of IL-5, CCL5 and IL-4, thus reducing secretion of eosinophil cationic protein. Furthermore, Del-1 significantly downregulated the expression of ICAM-1 and may have the potential to reduce leukocyte transendothelial migration. Our data demonstrate that Del-1 can negatively regulate IL-17 and its proinflammatory function, thereby limiting airway inflammation in allergic asthmatics, and suggest Del-1 as a potential candidate for prevention and treatment of allergic asthma.

IL-17 and related cytokines involved in systemic sclerosis: Perspectives

Systemic sclerosis (SSc) is a multisystemic, complex, and rare disease of connective tissue, with high morbidity and mortality, and without specific treatment. The disease is characterized by three main principles: vascular disease, autoantibody production and inflammation, and fibrosis. Since it is well defined that SSc is characterized by elevated production of TGF-β, IL-6, and IL-1, all of them cytokines related to Th17 differentiation, the hypothesis is that this disease may be strongly related to a polarization of the immune response towards the Th17 pathway. Considering the importance of a better understanding of the pathophysiology of Th17 pathway in SSc, this article aims to propose an update for a better understanding of current knowledge on main cytokines secreted by the Th17 cells (IL-17 A, IL-21, and IL-22) and the future prospects in the current disease.

Involvement of IL-17 in Secondary Brain Injury After a Traumatic Brain Injury in Rats

The pro-inflammatory activity of interleukin 17, which is produced by the IL-23/IL-17 axis, has been associated with the pathogenesis of traumatic brain injury (TBI). The study investigated the potential role of IL-17 in secondary brain injury of TBI in a rat model. Our data showed that the levels of IL-17 increased from 6 h to 7 days and peaked at 3 days, in both the CNS and serum, which were consistent with the severity of secondary brain injury. The IL-23 inhibitor suberoylanilide hydroxamic acid (SAHA) treatment markedly decreased the expressions of IL-17 and apoptosis-associated proteins cleaved caspase-3 and increased the protein ratio of Bcl-2 (B cell lymphoma/leukemia-2)/Bax (Bcl-2-associated X protein). Meanwhile, neuronal apoptosis was reduced, and neural function was improved after SAHA treatment. This study suggests that IL-17 is involved in secondary brain injury after TBI. Administering an IL-23 inhibitor and thereby blocking the IL-23/IL-17 axis may be beneficial in the treatment of TBI.