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[This corrects the article DOI: 10.3389/fimmu.2026.1740323.].

Cutaneous leishmaniasis, caused by protozoan parasites of the Leishmania genus, remains a significant health concern in endemic regions such as the Middle-East, Asia, Latin America, and North Africa. The disease affects millions of people worldwide, with over one million new infections reported annually. Despite its health impact, there is currently no approved vaccine largely due to limited understanding of immunological mechanisms underlying protective immunity and disease pathogenesis. We previously reported that long pentraxin 3 (PTX3), a pattern recognition molecule involved in inflammation, tissue repair, and wound healing, is a negative regulator of immunity in primary Leishmania major infection. Specifically, we showed that PTX3 exacerbates disease by suppressing protective Th17 responses. Here, we extend these findings by showing that PTX3 also influences secondary (memory) immunity to L. major . PTX3 -deficient ( PTX3 -/- ) mice which had resolved a primary infection exhibited enhanced resistance to secondary challenge compared to their wild-type (WT) controls. This enhanced resistance correlated with higher frequencies of effector memory CD4 + T cells in the spleens and draining lymph nodes. Upon re-infection, healed PTX3 -/- mice produced significantly more IL-17A, while levels of IFN-γ, TNF-α, and IL-10 were similar. In vivo BrdU incorporation assays further revealed increased proliferation of IL-17 + CD4 + T cells in PTX3 -/- mice. Importantly, neutralization of IL-17A during secondary challenge abolished the enhanced resistance observed in PTX3 -/- mice, confirming a central role of IL-17 in PTX3-regulated secondary immunity. Collectively, our findings identify PTX3 as a key regulator of secondary immunity in cutaneous leishmaniasis and underscores the importance of IL-17 in this process.

Interleukin (IL)-17A is a key driver of inflammation and the principal target of anti-IL-17 therapeutic monoclonal antibodies. IL-17A, and its structurally similar family member IL-17F, have been shown to be functionally dysregulated in certain human immune-mediated inflammatory diseases such as psoriasis, psoriatic arthritis, and axial spondyloarthritis. Given the overlapping biology of these two cytokines, we postulated that dual neutralization of IL-17A and IL-17F may provide a greater depth of clinical response in IL-17-mediated diseases than IL-17A inhibition alone. We identified 496.g1, a humanized antibody with strong affinity for IL-17A but poor affinity for IL-17F. Affinity maturation of 496.g1 to 496.g3 greatly enhanced the affinity of the Fab fragment for IL-17F while retaining strong binding to IL-17A. As an IgG1, the affinity for IL-17A and IL-17F was 3.2 pM and 23 pM, respectively. Comparison of 496.g3 IgG1 with the commercially available anti-IL-17A monoclonal antibodies ixekizumab and secukinumab, by surface plasmon resonance and in a human IL-17A functional assay, showed that 496.g3 and ixekizumab display equivalent affinity for IL-17A, and that both antibodies are markedly more potent than secukinumab. In contrast to ixekizumab and secukinumab, 496.g3 exhibited the unique feature of also being able to neutralize the biological activity of IL-17F. Therefore, antibody 496.g3 was selected for clinical development for its ability to neutralize the biologic function of both IL-17A and IL-17F and was renamed bimekizumab (formerly UCB4940). Early clinical data in patients with psoriasis, in those with psoriatic arthritis, and from the Phase 2 studies in psoriasis, psoriatic arthritis, and ankylosing spondylitis, are encouraging and support the targeted approach of dual neutralization of IL-17A and IL-17F. Taken together, these findings provide the rationale for the continued clinical evaluation of bimekizumab in patients with immune-mediated inflammatory diseases.

Interleukin (IL)-17A exists as a homodimer (A/A) or as a heterodimer (A/F) with IL-17F. IL-17A is expressed by a subset of T-cells, called Th17 cells, at inflammatory sites. Most cell types can respond to the local production of IL-17A because of the near ubiquitous expression of IL-17A receptors, IL-17RA and IL-17RC. IL-17A stimulates the release of cytokines and chemokines designed to recruit and activate both neutrophils and memory T-cells to the site of injury or inflammation and maintain a proinflammatory state. IL-17A-producing pathogenic T-cells contribute to the pathogenesis of autoimmune diseases, including psoriasis, psoriatic arthritis, rheumatoid arthritis, and ankylosing spondylitis. This study describes the generation and characterization of ixekizumab, a humanized IgG4 variant IL-17A-neutralizing antibody. Ixekizumab binds human and cynomolgus monkey IL-17A with high affinity and binds rabbit IL-17A weakly but does not bind to rodent IL-17A or other IL-17 family members. Ixekizumab effectively inhibits the interaction between IL-17A and its receptor in binding assays and potently blocks IL-17A-induced GRO or KC secretion in cell-based assays. In an in vivo mouse pharmcodynamic model, ixekizumab blocks human IL-17A-induced mouse KC secretion. These data provide a comprehensive preclinical characterization of ixekizumab, for which the efficacy and safety have been demonstrated in human clinical trials in psoriasis and psoriatic arthritis.

Paneth cells are intestinal epithelial cells that release antimicrobial peptides, such as α-defensin as part of host defense. Together with mesenchymal cells, Paneth cells provide niche factors for epithelial stem cell homeostasis. Here, we report two subtypes of murine Paneth cells, differentiated by their production and utilization of fucosyltransferase 2 (Fut2), which regulates α(1,2)fucosylation to create cohabitation niches for commensal bacteria and prevent invasion of the intestine by pathogenic bacteria. The majority of Fut2⁻ Paneth cells were localized in the duodenum, whereas the majority of Fut2⁺ Paneth cells were in the ileum. Fut2⁺ Paneth cells showed higher granularity and structural complexity than did Fut2⁻ Paneth cells, suggesting that Fut2⁺ Paneth cells are involved in host defense. Signaling by the commensal bacteria, together with interleukin 22 (IL-22), induced the development of Fut2⁺ Paneth cells. IL-22 was found to affect the α-defensin secretion system via modulation of Fut2 expression, and IL-17a was found to increase the production of α-defensin in the intestinal tract. Thus, these intestinal cytokines regulate the development and function of Fut2⁺ Paneth cells as part of gut defense.

Hongzhuo Yan,1,2,* Yu Chen,3,* Yali Song,1 Min Yan,1 Kexiang Yan1 1Dermatology Diagnosis and Treatment Center, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China; 2Shanghai University of Medicine & Health Sciences, Shanghai, People’s Republic of China; 3The First Affiliated Hospital of Harbin Medical University, Harbin, People’s Republic of China*These authors contributed equally to this workCorrespondence: Kexiang Yan, Email ykx2292002@aliyun.comAbstract: The interleukin-17A (IL-17A) cytokine is a key driver in the pathogenesis of chronic immune-mediated diseases, including psoriasis (PsO), psoriatic arthritis (PsA), and ankylosing spondylitis (AS). As a central proinflammatory mediator, IL-17A signals through the IL-17RA/RC receptor complex to promote tissue-specific inflammation. This narrative review outlines the therapeutic rationale for targeting IL-17A and summarizes the current evidence for vunakizumab, a novel humanized monoclonal antibody against IL-17A. We reviewed the biological basis of IL-17A signaling and its pathogenic role in PsO, PsA, and AS. We then synthesized the pharmacokinetic properties of vunakizumab and the clinical evidence from Phase II and III trials evaluating its efficacy and safety. Post hoc analyses across a broad range of clinically relevant patient subgroups further support the consistency of its therapeutic effects. Clinical trial data demonstrate that vunakizumab offers robust efficacy and a favorable safety profile in the treatment of psoriasis and spondyloarthritis (including PsA and AS). Its properties are comparable to other approved IL-17A inhibitors, establishing it as a promising therapeutic option for these IL-17A–mediated diseases.Keywords: IL-17A, psoriasis, psoriatic arthritis, ankylosing spondylitis, vunakizumab

Psoriasis is a frequent chronic inflammatory skin disease, nowadays considered a major global health problem. Several new drugs, targeting the IL-23/IL-17A pathway, have been recently licensed or are in clinical development. These therapies represent a major improvement of the way in which psoriasis is managed, since they show an unprecedented efficacy on skin symptoms of psoriasis. This has been made possible, thanks to an increasingly more accurate pathogenic view of psoriasis. Today, the belief that Th17 cells mediate psoriasis is moving to the concept of psoriasis as an IL-17A-driven disease. New questions arise at the horizon, given that IL-17A is part of a newly described family of cytokines, which has five distinct homologous: IL-17B, IL-17C, IL-17D, IL-17E, also known as IL-25 and IL-17F. IL-17 family cytokines elicit similar effects in target cells, but simultaneously trigger different and sometimes opposite functions in a tissue-specific manner. This is complicated by the fact that IL-17 cytokines show a high capacity of synergisms with other inflammatory stimuli. In this review, we will summarize the current knowledge around the cytokines belonging to the IL-17 family in relation to skin inflammation in general and psoriasis in particular, and discuss possible clinical implications. A comprehensive understanding of the different roles played by the IL-17 cytokines is crucial to appreciate current and developing therapies and to allow an effective pathogenesis- and mechanisms-driven drug design.

The interleukin-17A (IL-17A) cytokine is a key driver in the pathogenesis of chronic immune-mediated diseases, including psoriasis (PsO), psoriatic arthritis (PsA), and ankylosing spondylitis (AS). As a central proinflammatory mediator, IL-17A signals through the IL-17RA/RC receptor complex to promote tissue-specific inflammation. This narrative review outlines the therapeutic rationale for targeting IL-17A and summarizes the current evidence for vunakizumab, a novel humanized monoclonal antibody against IL-17A. We reviewed the biological basis of IL-17A signaling and its pathogenic role in PsO, PsA, and AS. We then synthesized the pharmacokinetic properties of vunakizumab and the clinical evidence from Phase II and III trials evaluating its efficacy and safety. Post hoc analyses across a broad range of clinically relevant patient subgroups further support the consistency of its therapeutic effects. Clinical trial data demonstrate that vunakizumab offers robust efficacy and a favorable safety profile in the treatment of psoriasis and spondyloarthritis (including PsA and AS). Its properties are comparable to other approved IL-17A inhibitors, establishing it as a promising therapeutic option for these IL-17A-mediated diseases.

Psoriasis is a chronic, immune-mediated, inflammatory disease that is pathogenically driven by proinflammatory cytokines. This article reviews the immunologic role of interleukin (IL)-17, the major effector cytokine in the pathogenesis of psoriatic disease, along with the rationale for targeting the IL-17 cytokine family (IL-17A, IL-17F, and IL-17 receptor A) in the treatment of psoriasis and psoriatic arthritis. Emerging evidence indicates that major sources of IL-17A in patients with psoriatic disease are mast cells, γδ T cells, αβ T cells, and innate lymphoid cells in lesional skin and synovial fluid. Within the skin and joints, IL-17A acts on cellular targets, including keratinocytes, neutrophils, endothelial cells, fibroblasts, osteoclasts, chondrocytes, and osteoblasts, to stimulate production of various antimicrobial peptides, chemokines, and proinflammatory and proliferative cytokines, which, in turn, promote tissue inflammation and bone remodeling. The critical importance of the IL-23/IL-17A axis to the pathogenesis of psoriatic disease has resulted in many new biologic treatments targeting these cytokines. These biologics dramatically improve skin and joint symptoms in patients with moderate-to-severe psoriasis and psoriatic arthritis.