αPD-1 immunotherapy promotes IL-17A production and promotes the formation of acute radiation-induced lung injury.

BACKGROUND: Radiotherapy (RT) is essential in the treatment of thoracic neoplasms. Immune checkpoint inhibitors targeting programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) have significantly improved the clinical management of non-small cell lung carcinoma (NSCLC). OBJECTIVE: This study aimed to investigate the impact of combining anti-PD-1 (αPD-1) immunotherapy with radiotherapy on lung injury. Additionally, it investigates the role and mechanism of interleukin (IL)-17A, a pro-inflammatory cytokine involved in immune regulation, in lung injury arising from this combination treatment. METHODS: Experiments were conducted using a PD-1 deficient mouse model to simulate acute radiation-induced lung injury. Inbred female BALB/c wild-type (WT) mice and PD-1-/- mice were divided into six groups: WT group, PD-1-/- group, WT_LIR + IgG group, PD-1-/-_LIR + IgG group, WT_LIR + αIL-17A group, and PD-1-/-_LIR + αIL-17A group. The mice were subjected to 8 Gy × 3 irradiation in both lungs. Various methods including histological scoring, immunofluorescence, qPCR, and flow cytometry were employed to analyze the role of IL-17A in lung injury and the effect of PD-1 gene deletion on the severity of radiation-induced lung injury. RESULTS: The PD-1-/-_LIR mice exhibited evident radiation-induced lung injury after receiving 8 Gy × 3 doses in both lungs. The expression level of IL-17A peaked at 2 weeks. Lung injury-related factors IFN-γ, TNF-α, IL-6, and RORγt in the PD-1-/-_LIR groups increased 2 weeks after irradiation. The CD4+ and CD8+ T cells in lung tissue of the PD-1-/-_LIR mice significantly increased. Post αIL-17A administration, the incidence of alveolitis in the treatment group decreased, the expression levels of lung injury-related factors IFN-γ, TNF-α, IL-6, RORγt, TGF-ß1, and IL-17A decreased, and the CD4+ and CD8+ T cells in lung tissue significantly declined. Throughout the observation period, the survival rate of the mice in the treatment group was significantly higher than that of the isotype control group (60% vs 0%, P = 0.011). CONCLUSION: Combining αPD-1 immunotherapy with radiotherapy in mice can induce radiation-induced lung injury, with IL-17A playing a critical role in this process. αIL-17A administration significantly mitigated radiation-induced lung injury caused by the combination of αPD-1 immunotherapy and radiotherapy, improving mouse survival. This finding offers a promising treatment target for lung injury resulting from the combination of αPD-1 immunotherapy and radiotherapy.

Transcutaneous auricular vagus nerve stimulation improves social deficits through the inhibition of IL-17a signaling in a mouse model of autism.

Background: Maternal exposure to inflammation is one of the causes of autism spectrum disorder (ASD). Electrical stimulation of the vagus nerve exerts a neuroprotective effect via its anti-inflammatory action. We thus investigated whether transcutaneous auricular vagus nerve stimulation (taVNS) can enhance social abilities in a mouse model of ASD induced by maternal immune activation (MIA). Methods: ASD mouse model were constructed by intraperitoneal injection of polyinosinic:polycytidylic acid (poly (I:C)). TaVNS with different parameters were tested in ASD mouse model and in C57BL/6 mice, then various behavioral tests and biochemical analyses related to autism were conducted. ASD model mice were injected with an interleukin (IL)-17a antibody into the brain, followed by behavioral testing and biochemical analyses. Results: TaVNS reduced anxiety, improved social function, decreased the number of microglia, and inhibited M1 polarization of microglia. Additionally, taVNS attenuated the expression of the IL-17a protein in the prefrontal cortex and blood of ASD model mice. To examine the possible involvement of IL-17a in taVNS-induced neuroprotection, we injected an IL-17a antibody into the prefrontal cortex of ASD model mice and found that neutralizing IL-17a decreased the number of microglia and inhibited M1 polarization. Furthermore, neutralizing IL-17a improved social function in autism model mice. Conclusion: Our study revealed that reduced neuroinflammation is an important mechanism of taVNS-mediated social improvement and neuroprotection against autism. This effect of taVNS could be attributed to the inhibition of the IL-17a pathway.

IL-17A Drives Oxidative Stress and Cell Growth in A549 Lung Epithelial Cells: Potential Protective Action of Oleuropein.

IL-17A drives inflammation and oxidative stress, affecting the progression of chronic lung diseases (asthma, chronic obstructive pulmonary disease (COPD), lung cancer, and cystic fibrosis). Oleuropein (OLP) is a polyphenolic compound present in olive oil and widely included in the Mediterranean diet. It exerts antioxidant and anti-inflammatory activities, oxidative stress resistance, and anticarcinogenic effects with a conceivable positive impact on human health. We hypothesized that OLP positively affects the mechanisms of oxidative stress, apoptosis, DNA damage, cell viability during proliferation, and cell growth in alveolar epithelial cells and tested its effect in a human alveolar epithelial cell line (A549) in the presence of IL-17A. Our results show that OLP decreases the levels of oxidative stress (Reactive Oxygen Species, Mitochondrial membrane potential) and DNA damage (H2AX phosphorylation-ser139, Olive Tail Moment data) and increases cell apoptosis in A549 cells exposed to IL-17A. Furthermore, OLP decreases the number of viable cells during proliferation, the migratory potential (Scratch test), and the single cell capacity to grow within colonies as a cancer phenotype in A549 cells exposed to IL-17A. In conclusion, we suggest that OLP might be useful to protect lung epithelial cells from oxidative stress, DNA damage, cell growth, and cell apoptosis. This effect might be exerted in lung diseases by the downregulation of IL-17A activities. Our results suggest a positive effect of the components of olive oil on human lung health.

Fluoride induces immunotoxicity by regulating riboflavin transport and metabolism partly through IL-17A in the spleen.

The impairment of the immune system by fluoride is a public health concern worldwide, yet the underlying mechanism is unclear. Both riboflavin and IL-17A are closely related to immune function and regulate the testicular toxicity of fluoride. However, whether riboflavin or IL-17A is involved in fluoride-induced immunotoxicity is unknown. Here, we first established a male ICR mouse model by treating mice with sodium fluoride (NaF) (100 mg/L) via the drinking water for 91 days. The results showed that fluoride increased the expression of the proinflammatory factors IL-1ß and IL-17A, which led to splenic inflammation and morphological injury. Moreover, the expression levels of the riboflavin transporters SLC52A2 and SLC52A3; the transformation-related enzymes RFK and FLAD1; and the key mitochondrial functional determinants SDH, COX, and ATP in the spleen were measured via real-time PCR, Western blotting, and ELISA. The results revealed that fluoride disrupted riboflavin transport, transformation, metabolism, and mitochondrial function. Furthermore, wild-type (WT) and IL-17A knockout (IL-17A-/-) C57BL/6 J male mice of the same age were treated with NaF (24 mg/kg·bw, equivalent to 100 mg/L) and/or riboflavin sodium phosphate (5 mg/kg·bw) via gavage for 91 days. Similar parameters were evaluated as above. The results confirmed that fluoride increased riboflavin metabolism through RFK but not through FLAD1. Fluoride also affected mitochondrial function and activated neutrophils (marked with Ly6g) and macrophages (marked with CD68) in the spleen. Interestingly, IL-17A partly mediated fluoride-induced riboflavin metabolism disorder and immunotoxicity in the spleen. This work not only reveals a novel toxic mechanism for fluoride but also provides new clues for exploring the physiological function of riboflavin and for diagnosing and treating the toxic effects of fluoride in the environment.

IL-17A exacerbates caspase-12-dependent neuronal apoptosis following ischemia through the Src-PLCγ-calpain pathway.

Interleukin-17 A (IL-17 A) contributes to inflammation and causes secondary injury in post-stroke patients. However, little is known regarding the mechanisms that IL-17 A is implicated in the processes of neuronal death during ischemia. In this study, the mouse models of middle cerebral artery occlusion/reperfusion (MCAO/R)-induced ischemic stroke and oxygen-glucose deprivation/reoxygenation (OGD/R)-simulated in vitro ischemia in neurons were employed to explore the role of IL-17 A in promoting neuronal apoptosis. Mechanistically, endoplasmic reticulum stress (ERS)-induced neuronal apoptosis was accelerated by IL-17 A activation through the caspase-12-dependent pathway. Blocking calpain or phospholipase Cγ (PLCγ) inhibited IL-17 A-mediated neuronal apoptosis under ERS by inhibiting caspase-12 cleavage. Src and IL-17 A are linked, and PLCγ directly binds to activated Src. This binding causes intracellular Ca2+ flux and activates the calpain-caspase-12 cascade in neurons. The neurological scores showed that intracerebroventricular (ICV) injection of an IL-17 A neutralizing mAb decreased the severity of I/R-induced brain injury and suppressed apoptosis in MCAO mice. Our findings reveal that IL-17 A increases caspase-12-mediated neuronal apoptosis, and IL-17 A suppression may have therapeutic potential for ischemic stroke.

Comparing machine learning screening approaches using clinical data and cytokine profiles for COVID-19 in resource-limited and resource-abundant settings.

Accurate screening of COVID-19 infection status for symptomatic patients is a critical public health task. Although molecular and antigen tests now exist for COVID-19, in resource-limited settings, screening tests are often not available. Furthermore, during the early stages of the pandemic tests were not available in any capacity. We utilized an automated machine learning (ML) approach to train and evaluate thousands of models on a clinical dataset consisting of commonly available clinical and laboratory data, along with cytokine profiles for patients (n = 150). These models were then further tested for generalizability on an out-of-sample secondary dataset (n = 120). We were able to develop a ML model for rapid and reliable screening of patients as COVID-19 positive or negative using three approaches: commonly available clinical and laboratory data, a cytokine profile, and a combination of the common data and cytokine profile. Of the tens of thousands of models automatically tested for the three approaches, all three approaches demonstrated > 92% sensitivity and > 88 specificity while our highest performing model achieved 95.6% sensitivity and 98.1% specificity. These models represent a potential effective deployable solution for COVID-19 status classification for symptomatic patients in resource-limited settings and provide proof-of-concept for rapid development of screening tools for novel emerging infectious diseases.

NR2E3 inhibits the inflammation and apoptosis in diabetic retinopathy by regulating the AHR/IL-17A signaling pathway.

Diabetic retinopathy (DR) is the most prevalent microvascular complication of diabetes mellitus, and it is the primary cause of blindness in the working-age population worldwide. Nevertheless, the pathogenic molecular mechanisms of DR remain elusive. Hub genes were identified through bioinformatics analysis in the GSE102485 and GSE60436 datasets. The DR mouse model was induced using streptozotocin (STZ, 150 mg/kg), and pathological changes in retinal tissue were assessed via HE staining. Apoptosis in retinal tissue cells was evaluated by the TUNEL assay. RT-qPCR and ELISA assays were employed to measure hub genes and inflammatory factor levels, respectively. The aryl hydrocarbon receptor (AHR)/interleukin (IL)-17A (AHR/IL-17A) pathway-associated proteins were detected by western blot. In the high glucose (HG)-induced ARPE-19 cells, CCK-8 and flow cytometry were used to perform cell function studies. Six hub genes associated with DR were screened. The expression levels of RHO, PRPH2, CRX, RCVRN, and NR2E3 were reduced, while the COL1A2 was elevated. NR2E3 overexpression reduced inflammatory factor (TNF-α, IL-1ß, and IL-6) and cell apoptosis levels in DR. Furthermore, NR2E3 overexpression promoted HG-induced ARPE-19 cell proliferation. Mechanistically, NR2E3 overexpression facilitated the protein expression of AHR, while suppressing the IL-17 and ACT1 expressions. The introduction of Kyn-101, an AHR inhibitor, notably reversed the inhibitory effects of NR2E3 overexpression on inflammation and apoptosis, which were validated both in vivo and in vitro. NR2E3 inhibits the inflammation and apoptosis by regulating the AHR/IL-17A pathway, providing new insights into the DR treatment.

Iguratimod ameliorates antibody-mediated rejection after renal transplant by modulating the Th17/Treg paradigm.

BACKGROUND: Iguratimod (IGU) is widely used in clinical practice due to its stable anti-inflammatory effects. Our previous studies have confirmed that the proportion of Th17/Treg balance in patients taking IGU altered significantly. This study aims to explore the role of IGU in antibody-mediated rejection (ABMR) and its potential mechanisms. METHODS: We conducted bioinformatics analysis of sequencing data from the GEO database to analyze the abundance of immune cell infiltration in transplanted kidney tissues. In vivo, IGU was intervened in a mice secondary skin transplantation model and a mice kidney transplantation ABMR model, and histological morphology of the grafts were examined by pathological staining, while relevant indicators were determined through qRT-PCR, immunohistochemistry, and enzyme-linked immunosorbent assay, observed T cell differentiation by flow cytometry, and preliminarily assessed the immunosuppressive effect of IGU. In vitro, we established Th17 and Treg cell induction and stimulation differentiation culture systems and added IGU for intervention to explore its effects on their differentiation. RESULTS: Through bioinformatics analysis, we found that Th17 and Treg may play important roles in the occurrence and development of ABMR. In vivo, we found that IGU could effectively reduce the damage caused by ABMR to the grafts, alleviate the infiltration of inflammatory cells in the graft tissues, and reduce the deposition of C4d in the grafts. Moreover, it is also found that IGU regulated the differentiation of Th17 and Treg cells in the spleen and peripheral blood and reduced the expression of IL-17A in the grafts and serum. In addition, same changes were observed in the induction and differentiation culture system of Th17 and Treg cells in vitro after the addition of IGU. CONCLUSION: IGU can inhibit the progression of ABMR by regulating the differentiation of Th17 and Treg cells, providing novel insights for optimizing clinical immunosuppressive treatment regimens.

IL-17A-induced cancer-associated fibroblasts releases CXCL12 to promote lung adenocarcinoma progression via Wnt/ß-Catenin signaling pathway.

BACKGROUND: Cancer-associated fibroblasts (CAFs) and their secretion, C-X-C motif chemokine ligand 12 (CXCL12), play an important role in the development of lung adenocarcinoma (LUAD). Interleukin 17A (IL-17A) is also crucial in regulating tumor progression. Herein, we explored the specific relationships between these two factors and their mechanisms in the progression of LUAD. METHODS: Immunohistochemistry was utilized to assess the differential expression levels of IL-17A and CXCL12 in tumor versus normal tissues of LUAD patients, followed by gene correlation analysis. Cell counting kit-8 (CCK8), wound-healing and transwell assays were performed to investigate the effect of IL-17A on the function of LUAD cells. qPCR, immunofluorescence, immunohistochemistry and western blot analyses were conducted to elucidate the potential mechanism by which IL-17A facilitates the development of LUAD via CXCL12. Male BALB-C nude mice were used to explore the role of IL-17A in subcutaneous LUAD mouse models. RESULTS: Elevated expression levels of IL-17A and CXCL12 were observed in LUAD tissues, exhibiting a positive correlation. Further studies revealed that IL-17A could stimulate CAFs to enhance the release of CXCL12, thereby facilitating the growth, proliferation, and metastasis of LUAD. The binding of CXCL12 to its specific receptor influences the activation of the Wnt/ß-Catenin pathway, which in turn affects the progression of LUAD. In vivo experiments have demonstrated that IL-17A enhances the growth of LUAD tumors by facilitating the secretion of CXCL12. Conversely, inhibiting CXCL12 has been demonstrated to impede tumor growth. CONCLUSIONS: We discovered that IL-17A promotes the release of CAFs-derived CXCL12, which in turn facilitates the development of LUAD via the Wnt/ß-Catenin signaling pathway.

Beta-adrenergic signaling and T-lymphocyte-produced catecholamines are necessary for interleukin 17A synthesis.

Background: Post-traumatic stress disorder (PTSD) is a debilitating psychological disorder that also presents with neuroimmune irregularities. Patients display elevated sympathetic tone and are at an increased risk of developing secondary autoimmune diseases. Previously, using a preclinical model of PTSD, we demonstrated that elimination of sympathetic signaling to T-lymphocytes specifically limited their ability to produce pro-inflammatory interleukin 17A (IL-17A); a cytokine implicated in the development of many autoimmune disorders. However, the mechanism linking sympathetic signaling to T-lymphocyte IL-17A production remained unclear. Methods: Using a modified version of repeated social defeat stress (RSDS) that allows for both males and females, we assessed the impact of adrenergic receptor blockade (genetically and pharmacologically) and catecholamine depletion on T-lymphocyte IL-17A generation. Additionally, we explored the impact of adrenergic signaling and T-lymphocyte-produced catecholamines on both CD4+ and CD8+ T-lymphocytes polarized to IL-17A-producing phenotypes ex vivo. Results: Only pharmacological inhibition of the beta 1 and 2 adrenergic receptors (ß1/2) significantly decreased circulating IL-17A levels after RSDS, but did not impact other pro-inflammatory cytokines (e.g., IL-6, TNF-α, and IL-10). This finding was confirmed using RSDS with both global ß1/2 receptor knock-out mice, as well as by adoptively transferring ß1/2 knock-out T-lymphocytes into immunodeficient hosts. Furthermore, ex vivo polarized T-lymphocytes produced significantly less IL-17A with the blockade of ß1/2 signaling, even in the absence of exogenous sympathetic neurotransmitter supplementation, which suggested T-lymphocyte-produced catecholamines may be involved in IL-17A production. Indeed, pharmacological depletion of catecholamines both in vivo and ex vivo abrogated T-lymphocyte IL-17A production demonstrating the importance of immune-generated neurotransmission in pro-inflammatory cytokine generation. Conclusions: Our data depict a novel role for ß1/2 adrenergic receptors and autologous catecholamine signaling during T-lymphocyte IL-17A production. These findings provide a new target for pharmacological therapy in both psychiatric and autoimmune diseases associated with IL-17A-related pathology.

DNMT inhibitor, 5-aza-2'-deoxycytidine mitigates di(2-ethylhexyl) phthalate-induced aggravation of psoriasiform inflammation in mice via reduction in global DNA methylation in dermal and peripheral compartments.

Psoriasis is classified as an autoimmune disorder characterized by abnormal immune response leading to the development of chronic dermal inflammation. Most individuals have a genetic vulnerability that may be further influenced by epigenetic changes occurring due to multiple variables such as pollutant exposure. Epigenetic modifications such as DNA methylation possess a dynamic nature, enabling cellular differentiation and adaptation by controlling gene expression. Di(2-ethylhexyl) phthalate (DEHP) and psoriatic inflammation are known to cause modification of DNA methylation via DNA methyltransferase (DNMT). However, it is not known whether DEHP, a ubiquitous plasticizer affects psoriatic inflammation via DNMT modulation. Therefore, this study investigated the effect of DNMT inhibitor, 5-aza-2'-deoxycytidine (AZA) on DEHP-induced changes in the expression of DNMT1, global DNA methylation, and anti-/inflammatory parameters (p-STAT3, IL-17A, IL-6, iNOS, IL-10, Foxp3, Nrf2, HO-1) in the skin and the peripheral adaptive/ myeloid immune cells (CD4+ T cells/CD11b+ cells) in imiquimod (IMQ) model of psoriasiform inflammation. Further, psoriasis-associated clinical/histopathological features (ear thickness, ear weight, ear PASI score, MPO activity, and H&E staining of the ear and the back skin) were also analyzed in IMQ model. Our data show that IMQ-treated mice with DEHP exposure had increased DNMT1 expression and DNA methylation which was associated with elevated inflammatory (p-STAT3, IL-17A, IL-6, iNOS) and downregulated anti-inflammatory mediators (IL-10, Foxp3, Nrf2, HO-1) in the peripheral immune cells (CD4+ T cells/CD11b+ cells) and the skin as compared to IMQ-treated mice. Treatment with DNMT1 inhibitor caused reduction in inflammatory and elevation in anti-inflammatory parameters with significant improvement in clinical/histopathological symptoms in both IMQ-treated and DEHP-exposed IMQ-treated mice. In conclusion, our study shows strong evidence indicating that DNMT1 plays an important role in DEHP-induced exacerbation of psoriasiform inflammation in mice through hypermethylation of DNA.

Si-Miao-Yong-An Decoction alleviates thromboangiitis obliterans by regulating miR-548j-5p/IL-17A signaling pathway.

Thromboangiitis obliterans (TAO) is a rare, chronic, progressive, and segmental inflammatory disease characterized by a high rate of amputation, significantly compromising the quality of life of patients. Si-Miao-Yong-An decoction (SMYA), a traditional prescription, exhibits anti-inflammatory, anti-thrombotic, and various other pharmacological properties. Clinically, it was fully proved to be effective for TAO therapy, but the specific therapeutic effect of SMYA on TAO has been unknown. Thus, deep unveiling the mechanism of SMYA in TAO for identifying clinical therapeutic targets is extremely important. In this study, we observed elevated levels of IL-17A in the peripheral blood mononuclear cells (PBMCs) of TAO patients, whereas the expression of miR-548j-5p was significantly decreased. A negative correlation between the levels of miR-548j-5p and IL-17A was also demonstrated. In vitro experiments showed that overexpression of miR-548j-5p led to a decrease in IL-17A levels, whereas downregulation of miR-548j-5p showed the opposite effect. Using a dual luciferase assay, we confirmed that miR-548j-5p directly targets IL-17A. Furthermore, serum containing SMYA effectively decreased IL-17A levels by increasing the expression of miR-548j-5p. More importantly, the results of in vivo tests indicated that SMYA mitigated the development of TAO by inhibiting IL-17A through the upregulation of miR-548j-5p in vascular tissues. In conclusion, SMYA significantly enhances the expression of miR-548j-5p, thereby reducing the levels of the target gene IL-17A and alleviating TAO. Our research not only identifies novel targets and pathways for the clinical diagnosis and treatment of TAO but also advances the innovation in traditional Chinese medicine through the elucidation of the SMYA/miR-548j-5p/IL-17A regulatory axis in the pathogenesis of TAO.

Interleukin-17A educated hepatic stellate cells promote hepatocellular carcinoma occurrence through fibroblast activation protein expression.

BACKGROUND: Liver cancer is typified by a complex inflammatory tumor microenvironment, where an array of cytokines and stromal cells orchestrate a milieu that significantly influences tumorigenesis. Interleukin-17A (IL-17A), a pivotal pro-inflammatory cytokine predominantly secreted by Th17 cells, is known to play a substantial role in the etiology and progression of liver cancer. However, the precise mechanism by which IL-17A engages with hepatic stellate cells (HSCs) to facilitate the development of hepatocellular carcinoma (HCC) remains to be fully elucidated. This investigation seeks to unravel the interplay between IL-17A and HSCs in the context of HCC. METHODS: An HCC model was established in male Sprague-Dawley rats using diethylnitrosamine to explore the roles of IL-17A and HSCs in HCC pathogenesis. In vivo overexpression of Il17a was achieved using adeno-associated virus. A suite of molecular techniques, including RT-qPCR, enzyme-linked immunosorbent assays, Western blotting, cell counting kit-8 assays and colony formation assays, was employed for in vitro analyses. RESULTS: The study findings indicate that IL-17A is a key mediator in HCC promotion, primarily through the activation of hepatic progenitor cells (HPCs). This pro-tumorigenic influence appears to be mediated by HSCs, rather than through a direct effect on HPCs. Notably, IL-17A-induced expression of fibroblast activation protein (FAP) in HSCs emerged as a critical factor in HCC progression. Silencing Fap in IL-17A-stimulated HSCs was observed to reverse the HCC-promoting effects of HSCs. CONCLUSIONS: The collective evidence from this study implicates the IL-17A/FAP signaling axis within HSCs as a contributor to HCC development by enhancing HPC activation. These findings bolster the potential of IL-17A as a diagnostic and preventative target for HCC, offering new avenues for therapeutic intervention.

IL-17A and TNF-α-induced Dectin-1 expression may promote keratinocyte proliferation in psoriatic lesions.

Psoriasis is a common skin disease with a high recurrence rate. Aberrant keratinocyte proliferation is a significant pathogenic characteristic of psoriatic lesions, and studies have revealed that the development of psoriasis is significantly influenced by pro-inflammatory cytokines, such as IL-17A and TNF-α. Biologics targeting these cytokines have been widely used in psoriasis treatment and achieve remarkable effects, however, the underlying mechanism of how IL-17A and TNF-α specifically regulate keratinocyte proliferation has not been fully elucidated. Dectin-1 is an essential membrane protein that is directly related to the immune microenvironment and the proliferation of multiple cell types. To elucidate how IL-17A and TNF-α may promote keratinocyte proliferation in psoriatic lesions and whether Dectin-1 is involved. The expression of Dectin-1 in keratinocytes from psoriatic lesions was detected by real-time PCR, western blot and immunofluorescence. Correlation analysis and cytological experiments were then performed to determine the relationship between Dectin-1 and IL-17A/TNF-α in psoriatic lesions. Finally, we investigated the signalling pathway through which Dectin-1 may promote keratinocyte proliferation. Dectin-1 was significantly increased in keratinocytes from psoriatic lesions. Moreover, IL-17A and TNF-α effectively induced the expression of Dectin-1 in HaCaT cells, which was shown to activate the Syk/NF-κB signalling pathway and promote the proliferation of keratinocytes. IL-17A and TNF-α may promote the proliferation of keratinocytes in psoriatic lesions through induction of Dectin-1, indicating that Dectin-1 could be a potential therapeutic target for the treatment of psoriasis.

IL-17A enhances the inflammatory response of glaucoma through Act1/TRAF6/NF-κB pathway.

OBJECTIVES: To investigate the possible roles of Interleukin 17A (IL-17A) and IL-17A neutralizing antibodies (IL-17Ab) in glaucoma and the potential mechanisms. METHODS: The two glaucoma animal models, chronic ocular hypertension (COH) and N-methyl-D-aspartate (NMDA)-induced retinal ganglion cell (RGC) damage, were established and treated with intravitreal injection of IL-17A or IL-17Ab. Intraocular pressure (IOP) was measured by a rebound tonometer. The retina and RGC injury were evaluated by HE staining, TUNLE assay and Brn3a immunofluorescence staining. The frequency of IL-17A+CD4+T cells in peripheral blood was detected by flow cytometry. The expression of glial fibrillary acidic protein (GFAP) was detected by immunofluorescence staining, Western Blot and qPCR in retina. The RNA and protein expression of Act1/TRAF6/NF-κB were detected by Western Blot and qPCR in retina. RESULTS: The expression of IL-17A increased in glaucoma models. After intravitreal injection of IL-17A, in the retina, the number of RGCs decreased, the apoptosis of RGCs increased, the Müller cell gliosis was more obvious. In addition, peripheral inflammation aggravated. Whereas the intravitreal injection of IL-17Ab alleviated the relevant manifestations and peripheral inflammation, reduced the gliosis of Müller cells. In the COH model, IOP increased after the injection of IL-17A, while the intravitreal injection of IL-17Ab led to a decrease in IOP. Furthermore, IL-17A promotes the apoptosis of RGCs by binding to IL-17A receptor, activating Act1/TRAF6/NF-κB pathways. CONCLUSION: IL-17A plays a role in and aggravates RGC damage in glaucoma. IL-17Ab can neutralize the pro-inflammatory effect of IL-17A and have a protective function in glaucoma. These findings reveal the importance of IL-17A in the pathogenesis of glaucoma, which will shed light on a novel direction for the prevention and treatment of glaucoma, and also provide a reference for further research on other retinal diseases.

Pharmacokinetics, Safety, and Immunogenicity of Intravenous and Subcutaneous Single-Dose QX002N Injection in Healthy Subjects: A Randomized, Open, Parallel, Single-Center, Phase I Study.

INTRODUCTION: Interleukin-17A (IL-17A) plays a crucial role in the pathogenesis of ankylosing spondylitis (AS), although not all patients respond to traditional IL-17A antibody treatments. QX002N injection, as a new monoclonal antibody targeting IL-17A, has shown potential in treating AS, offering a new treatment option for patients who do not respond well to existing therapies. METHODS: A randomized, open, parallel, single-center, phase I study was conducted to assess the pharmacokinetics, safety, and immunogenicity of single doses of QX002N injection administered intravenously (IV) or subcutaneously (SC) to healthy Chinese volunteers. Blood samples were collected at specified time intervals, and then serum concentrations of QX002N were analyzed by enzyme-linked immunosorbent assay. RESULTS: Pharmacokinetic analysis of the drug concentration-time data showed that the mean maximum observed serum QX002N concentration (Cmax) was 110 and 33.9 µg/ml, respectively. The average area under the drug concentration-time curves from 0 to the time of the last quantifiable concentration (AUClast) were 52,656 and 36,269 µg·h/ml, respectively and the average area under the drug concentration-time curves from 0 to infinity (AUCinf) were 54,867 and 38,194 µg·h/ml, respectively. The absolute bioavailability of QX002N after SC injection was 69.6%. CONCLUSIONS: Immunogenicity was assessed and all the subjects in this study were Anti-drug antibody (ADA)-negative, which means no subjects appeared to develop immunogenicity to QX002N. All the results testify to the safety of QX002N injection, which is satisfactory after IV or SC dosing in healthy subjects. TRIAL REGISTRATION: www.chinadrugtirals.org.cn , CTR20220430.

Modulation of Alzheimer's disease brain pathology in mice by gut bacterial depletion: the role of IL-17a.

Gut bacteria regulate brain pathology of Alzheimer's disease (AD) patients and animal models; however, the underlying mechanism remains unclear. In this study, 3-month-old APP-transgenic female mice with and without knock-out of Il-17a gene were treated with antibiotics-supplemented or normal drinking water for 2 months. The antibiotic treatment eradicated almost all intestinal bacteria, which led to a reduction in Il-17a-expressing CD4-positive T lymphocytes in the spleen and gut, and to a decrease in bacterial DNA in brain tissue. Depletion of gut bacteria inhibited inflammatory activation in both brain tissue and microglia, lowered cerebral Aß levels, and promoted transcription of Arc gene in the brain of APP-transgenic mice, all of which effects were abolished by deficiency of Il-17a. As possible mechanisms regulating Aß pathology, depletion of gut bacteria inhibited ß-secretase activity and increased the expression of Abcb1 and Lrp1 in the brain or at the blood-brain barrier, which were also reversed by the absence of Il-17a. Interestingly, a crossbreeding experiment between APP-transgenic mice and Il-17a knockout mice further showed that deficiency of Il-17a had already increased Abcb1 and Lrp1 expression at the blood-brain barrier. Thus, depletion of gut bacteria attenuates inflammatory activation and amyloid pathology in APP-transgenic mice via Il-17a-involved signaling pathways. Our study contributes to a better understanding of the gut-brain axis in AD pathophysiology and highlights the therapeutic potential of Il-17a inhibition or specific depletion of gut bacteria that stimulate the development of Il-17a-expressing T cells.

VISTA Deficiency Exacerbates the Development of Pulmonary Fibrosis by Promoting Th17 Differentiation.

Background: Interstitial lung disease (ILD), characterized by pulmonary fibrosis (PF), represents the end-stage of various ILDs. The immune system plays an important role in the pathogenesis of PF. V-domain immunoglobulin suppressor of T-cell activation (VISTA) is an immune checkpoint with immune suppressive functions. However, its specific role in the development of PF and the underlying mechanisms remain to be elucidated. Methods: We assessed the expression of VISTA in CD4 T cells from patients with connective tissue disease-related interstitial lung disease (CTD-ILD). Spleen cells from wild-type (WT) or Vsir -/- mice were isolated and induced for cell differentiation in vitro. Additionally, primary lung fibroblasts were isolated and treated with interleukin-17A (IL-17A). Mice were challenged with bleomycin (BLM) following VISTA blockade or Vsir knockout. Moreover, WT or Vsir -/- CD4 T cells were transferred into Rag1 -/- mice, which were then challenged with BLM. Results: VISTA expression was decreased in CD4 T cells from patients with CTD-ILD. Vsir deficiency augmented T-helper 17 (Th17) cell differentiation in vitro. Furthermore, IL-17A enhanced the production of inflammatory cytokines, as well as the differentiation and migration of lung fibroblasts. Both VISTA blockade and knockout of Vsir increased the percentage of IL-17A-producing Th17 cells and promoted BLM-induced PF. In addition, mice receiving Vsir -/- CD4 T cells exhibited a higher percentage of Th17 cells and more severe PF compared to those receiving WT CD4 T cells. Conclusion: These findings demonstrate the significant role of VISTA in modulating the development of PF by controlling Th17 cell differentiation. These insights suggest that targeting VISTA could be a promising therapeutic strategy for PF.

Development of a nano-emulsion based multivalent protein subunit vaccine against Pseudomonas aeruginosa.

Pseudomonas aeruginosa (Pa) is an opportunistic bacterial pathogen responsible for severe hospital acquired infections in immunocompromised and elderly individuals. Emergence of increasingly drug resistant strains and the absence of a broad-spectrum prophylactic vaccine against both T3SA+ (type III secretion apparatus) and ExlA+/T3SA- Pa strains worsen the situation in a post-pandemic world. Thus, we formulated a candidate subunit vaccine (called ExlA/L-PaF/BECC/ME) against both Pa types. This bivalent vaccine was generated by combining the C-terminal active moiety of exolysin A (ExlA) produced by non-T3SA Pa strains with our T3SA-based vaccine platform, L-PaF, in an oil-in-water emulsion. The ExlA/L-PaF in ME (MedImmune emulsion) was then mixed with BECC438b, an engineered lipid A analogue and a TLR4 agonist. This formulation was administered intranasally (IN) to young and elderly mice to determine its potency across a diverse age-range. The elderly mice were used to mimic the infection seen in elderly humans, who are more susceptible to serious Pa disease compared to their young adult counterparts. After Pa infection, mice immunized with ExlA/L-PaF/BECC/ME displayed a T cell-mediated adaptive response while PBS-vaccinated mice experienced a rapid onset inflammatory response. Important genes and pathways were observed, which give rise to an anti-Pa immune response. Thus, this vaccine has the potential to protect aged individuals in our population from serious Pa infection.

Propionic acid ameliorates cognitive function through immunomodulatory effects on Th17 cells in perioperative neurocognitive disorders.

Background: Elderly patients undergoing surgery are prone to cognitive decline known as perioperative neurocognitive disorders (PND). Several studies have shown that the microglial activation and the decrease of short-chain fatty acids (SCFAs) in gut induced by surgery may be related to the pathogenesis of PND. The purpose of this study was to determine whether microglia and short-chain fatty acids were involved in cognitive dysfunction in aged rats. Methods: Male wild-type Wistar rats aged 11-12 months were randomly divided into control group (Ctrl: Veh group), propionic acid group (Ctrl: PA group), exploratory laparotomy group (LP: Veh group) and propionic acid + exploratory laparotomy group (LP: PA group) according to whether exploratory laparotomy (LP) or PA pretreatment for 21 days was performed. The motor ability of the rats was evaluated by open field test on postoperative day 3 (POD3), and then the cognitive function was evaluated by Y-maze test and fear conditioning test. The expression of IL-1ß, IL-6, RORγt and IL-17A mRNA in hippocampus was detected by RT-qPCR, the expression of IL-17A and IL-17RA in hippocampus was detected by Western blot, and the activation of microglia was detected by immunofluorescence. Results: The PND rat model was successfully established by laparotomy. Compared with Ctrl: Veh group, the body weight of LP: Veh group decreased, the percentage of spontaneous alternations in Y maze decreased (P < 0.001), and the percentage of freezing time in contextual fear test decreased (P < 0.001). Surgery triggers neuroinflammation, manifested as the elevated levels of the inflammatory cytokines IL-1ß (P < 0.001) and IL-6 (P < 0.001), the increased expression of the transcription factor RORγt (P = 0.0181, POD1; P = 0.0073, POD5)and major inflammatory cytokines IL-17A (P = 0.0215, POD1; P = 0.0071, POD5), and the increased average fluorescence intensity of Iba1 (P < 0.001, POD1; P < 0.001, POD5). After PA preconditioning, the recovery of rats in LP: PA group was faster than that in LP: Veh group as the body weight lost on POD1 (P = 0.0148) was close to the baseline level on POD5 (P = 0.1846), and they performed better in behavioral tests. The levels of IL-1ß (P < 0.001) and IL-6 (P = 0.0035) inflammatory factors in hippocampus decreased on POD1 and the average fluorescence intensity of Iba1 decreased (P = 0.0024, POD1; P < 0.001, POD5), representing the neuroinflammation was significantly improved. Besides, the levels of RORγt mRNA (P = 0.0231, POD1; P = 0.0251, POD5) and IL-17A mRNA (P = 0.0208, POD1; P = 0.0071, POD5) in hippocampus as well as the expression of IL-17A (P = 0.0057, POD1; P < 0.001, POD5) and IL-17RA (P = 0.0388) decreased. Conclusion: PA pretreatment results in reduced postoperative neuroinflammation and improved cognitive function, potentially attributed to the regulatory effects of PA on Th17-mediated immune responses.