Prostaglandin E2 and IL-23 interconnects STAT3 and RoRγ pathways to initiate Th17 CD4+ T-cell development during rheumatoid arthritis

The immunologic role of IL-23 in psoriatic arthritis: a potential therapeutic target

INTRODUCTION

Psoriatic arthritis (PsA) is a debilitating chronic condition characterized by inflammation of the joints, bones, enthesis, and skin. The pivotal role of interleukin-23 (IL-23) in the pathogenesis of PsA has become increasingly evident. This proinflammatory cytokine is markedly elevated in patients with PsA, suggesting its potential as a therapeutic target. Consequently, IL-23 inhibitors have emerged as promising first-line biologic treatments for PsA.

AREAS COVERED

This review delves into the immunopathogenic mechanisms of IL-23 at the cellular and molecular levels in PsA. Furthermore, it provides the recent efficacy and safety profiles of IL-23 inhibitors. We conducted a literature search in PubMed for the following terms: 'IL-23 and psoriatic arthritis,' 'Ustekinumab,' 'Guselkumab,' 'Risankizumab,' and 'Tildrakizumab.' In addition, we retrieved clinical trials involving IL-23 inhibitors registered in ClinicalTrials.gov, EudraCT, and ICTRP.

EXPERT OPINION

Despite the promising outcomes observed with IL-23 inhibitors, several challenges persist. The long-term effects of these agents require further investigation through prospective studies, and their limited accessibility worldwide necessitates urgent attention. Additionally, ongoing research is warranted to explore other potential drug targets within the IL-23/IL-23 R axis. The development of reliable biomarkers could greatly enhance early detection, tailored management strategies, and personalized treatment approaches for patients with PsA.

Mitochondria: a breakthrough in combating rheumatoid arthritis

As a chronic autoimmune disease with complex aetiology, rheumatoid arthritis (RA) has been demonstrated to be associated with mitochondrial dysfunction since mitochondrial dysfunction can affect the survival, activation, and differentiation of immune and non-immune cells involved in the pathogenesis of RA. Nevertheless, the mechanism behind mitochondrial dysfunction in RA remains uncertain. Accordingly, this review addresses the possible role and mechanisms of mitochondrial dysfunction in RA and discusses the potential and challenges of mitochondria as a potential therapeutic strategy for RA, thereby providing a breakthrough point in the prevention and treatment of RA.

Prostaglandin E2 promotes Th17 differentiation induces corneal epithelial cell apoptosis and participates in the progression of dry eye

This study is mainly based on T helper type 17 (Th17) cells analysis of the mechanism of prostaglandin E2 (PGE2) promoting the progression of dry eye (DE). Scopolamine and dry environment were used to induce mice DE model. Celecoxib was used to inhibit PGE2. Corneal epithelial cells and CD4+ T cells were used to construct a co-culture system. The osmotic pressure was increased by adding NaCl to simulate DE in vitro. AH6809 and E7046 were used to pre-culture to inhibit EP2/4 in T cells to verify the effect of exogenous PGE2 on Th17 cell differentiation and corneal epithelial cell apoptosis. The function of Th17 cells was analyzed by detecting RORγt and interleukin-17 (IL-17). PGE2 was instilled on the ocular surface to induce DE symptoms of mice. AH6809 and E7046 were used to inhibit EP2/4. The corneal epithelial cell apoptosis was observed by TUNEL. The proportion of Th17 cells in corneal tissue and draining lymph nodes (DLNs) was detected by flow cytometry. In DE mice, the concentration of PGE2 and IL-17 increased in tears, and the proportion of Th17 increased, while inhibition of PGE2 alleviated the symptoms of DE and inhibited Th17 differentiation. Hypertonic environment induces corneal epithelial cells to secrete PGE2. PGE2 promoted the expression of EP2/4 and the differentiation of Th17 cells in vitro. The hypertonic environment promoted PGE2 level and the apoptosis of corneal epithelial cells in the co-culture system. PGE2 alone did not cause corneal epithelial cell apoptosis, while PGE2 promoted apoptosis by promoting Th17. Blocking EP2/4 reduced the induction of Th17 differentiation by PGE2 and the promoted corneal epithelial cell apoptosis. Animal experiments showed that exogenous PGE2 induced DE symptoms. Blocking EP2/4 not only inhibited the proportion of Th17, but also alleviated the apoptosis of corneal epithelial cells caused by PGE2. PGE2 induces aggravation of inflammation by promoting the level of Th17 in the ocular surface, and causes corneal epithelial cell apoptosis, thereby participating in the progression of DE.

The role of retinoic acid receptor-related orphan receptors in skeletal diseases

Bone homeostasis, depending on the balance between bone formation and bone resorption, is responsible for maintaining the proper structure and function of the skeletal system. As an important group of transcription factors, retinoic acid receptor-related orphan receptors (RORs) have been reported to play important roles in bone homeostasis by regulating the transcription of target genes in skeletal cells. On the other hand, the dysregulation of RORs often leads to various skeletal diseases such as osteoporosis, rheumatoid arthritis (RA), and osteoarthritis (OA). Herein, we summarized the roles and mechanisms of RORs in skeletal diseases, aiming to provide evidence for potential therapeutic strategies.

Harnessing prostaglandin E2 signaling to ameliorate autoimmunity

The etiology of most autoimmune diseases remains unknown; however, shared among them is a disruption of immunoregulation. Prostaglandin lipid signaling molecules possess context-dependent immunoregulatory properties, making their role in autoimmunity difficult to decipher. For example, prostaglandin E2 (PGE2) can function as an immunosuppressive molecule as well as a proinflammatory mediator in different circumstances, contributing to the expansion and activation of T cell subsets associated with autoimmunity. Recently, PGE2 was shown to play important roles in the resolution and post-resolution phases of inflammation, promoting return to tissue homeostasis. We propose that PGE2 plays both proinflammatory and pro-resolutory roles in the etiology of autoimmunity, and that harnessing this signaling pathway during the resolution phase might help prevent autoimmune attack.

Transdermal delivery of inflammatory factors regulated drugs for rheumatoid arthritis

Rheumatoid arthritis is a chronic autoimmune disease, with the features of recurrent chronic inflammation of synovial tissue, destruction of cartilage, and bone erosion, which further affects joints tissue, organs, and systems, and eventually leads to irreversible joint deformities and body dysfunction. Therapeutic drugs for rheumatoid arthritis mainly reduce inflammation through regulating inflammatory factors. Transdermal administration is gradually being applied to the treatment of rheumatoid arthritis, which can allow the drug to overcome the skin stratum corneum barrier, reduce gastrointestinal side effects, and avoid the first-pass effect, thus improving bioavailability and relieving inflammation. This paper reviewed the latest research progress of transdermal drug delivery in the treatment of rheumatoid arthritis, and discussed in detail the dosage forms such as gel (microemulsion gel, nanoemulsion gel, nanomicelle gel, sanaplastic nano-vesiclegel, ethosomal gel, transfersomal gel, nanoparticles gel), patch, drug microneedles, nanostructured lipid carrier, transfersomes, lyotropic liquid crystal, and drug loaded electrospinning nanofibers, which provide inspiration for the rich dosage forms of transdermal drug delivery systems for rheumatoid arthritis.

Prostaglandins and non-steroidal anti-inflammatory drugs in Covid-19

In response to different viral infections, including SARS-CoV-2 infection, pro-inflammatory, anti-inflammatory cytokines, and bioactive lipids are released from infected and immune cells. One of the most critical bioactive lipids is prostaglandins (PGs) which favor perseverance of inflammation leading to chronic inflammation as PGs act as cytokine amplifiers. PGs trigger the release of pro-inflammatory cytokines, activate Th cells, recruit immune cells, and increase the expression of pro-inflammatory genes. Therefore, PGs may induce acute and chronic inflammations in various inflammatory disorders and viral infections like SARS-CoV-2. PGs are mainly inhibited by non-steroidal anti-inflammatory drugs (NSAIDs) by blocking cyclooxygenase enzymes (COXs), which involve PG synthesis. NSAIDs reduce inflammation by selective or non-selective blocking activity of COX2 or COX1/2, respectively. In the Covid-19 era, there is a tremendous controversy regarding the use of NSAIDs in the management of SARS-CoV-2 infection. As well, the possible role of PGs in the pathogenesis of SARS-CoV-2 infection is not well-defined. Thus, the objective of the present study is to review the potential role of PGs and NSAIDs in Covid-19 in a narrative review regarding the preponderance of assorted views.

DYSF promotes monocyte activation in atherosclerotic cardiovascular disease as a DNA methylation-driven gene

Dysferlin (DYSF) has drawn much attention due to its involvement in dysferlinopathy and was reported to affect monocyte functions in recent studies. However, the role of DYSF in the pathogenesis of atherosclerotic cardiovascular diseases (ASCVD) and the regulation mechanism of DYSF expression have not been fully studied. In this study, Gene Expression Omnibus (GEO) database and epigenome-wide association study (EWAS) literatures were searched to find the DNA methylation-driven genes (including DYSF) of ASCVD. The hub genes related to DYSF were also identified through weighted correlation network analysis (WGCNA). Regulation of DYSF expression through its promoter methylation status was verified using peripheral blood leucocytes (PBLs) from ASCVD patients and normal controls, and experiments on THP1 cells and Apoe^-/- mice. Similarly, the expressions of DYSF related hub genes, mainly contained SELL, STAT3 and TMX1, were also validated. DYSF functions were then evaluated by phagocytosis, transwell and adhesion assays in DYSF knock-down and overexpressed THP1 cells. The results showed that DYSF promoter hypermethylation up-regulated its expression in clinical samples, THP1 cells and Apoe^-/- mice, confirming DYSF as a DNA methylation-driven gene. The combination of DYSF expression and methylation status in PBLs had a considerable prediction value for ASCVD. Besides, DYSF could enhance the phagocytosis, migration and adhesion ability of THP1 cells. Among DYSF related hub genes, SELL was proven to be the downstream target of DYSF by wet experiments. In conclusion, DYSF promoter hypermethylation upregulated its expression and promoted monocytes activation, which further participated in the pathogenesis of ASCVD.

Metabolomics in rheumatoid arthritis: Advances and review

Rheumatoid arthritis (RA) is an autoimmune disease accompanied by metabolic alterations. The metabolic profiles of patients with RA can be determined using targeted and non-targeted metabolomics technology. Metabolic changes in glucose, lipid, and amino acid levels are involved in glycolysis, the tricarboxylic acid cycle, the pentose phosphate pathway, the arachidonic acid metabolic pathway, and amino acid metabolism. These alterations in metabolic pathways and metabolites can fulfill bio-energetic requirements, promote cell proliferation, drive inflammatory mediator secretion, mediate leukocyte infiltration, induce joint destruction and muscle atrophy, and regulate cell proliferation, which may reflect the etiologies of RA. Differential metabolites can be used as biomarkers for the diagnosis, prognosis, and risk prediction, improving the specificity and accuracy of diagnostics and prognosis prediction. Additionally, metabolic changes associated with therapeutic responses can improve the understanding of drug mechanism. Metabolic homeostasis and regulation are new therapeutic strategies for RA. In this review, we provide a comprehensive overview of advances in metabolomics for RA.

Research progress on serological indices and their clinical application in rheumatoid arthritis

BACKGROUND

As a chronic systemic autoimmune disease of undetermined etiology, rheumatoid arthritis (RA) has a complex pathogenesis, which involves multiple proteins and cytokines. The 2010 ACR/EULAR classification criteria facilitate early diagnosis of RA with reduced specificity when compared to the 1987 ACR criteria. Hence, it is imperative to identify novel serological inflammatory indicators and targets, in order to explain the complex regulatory network of RA. The present review discusses the associations of various inflammatory factors with RA and its underlying mechanism. Besides, the review also provides a novel insight into the clinical treatment of RA.

MATERIALS AND METHODS

According to the PRISMA guidelines, databases like Web of Science, Google-Scholar, Pubmed and Scopus were systematically searched for articles from January 1, 2018 to January 1, 2022 using The following 2 keywords: "rheumatoid arthritis", "Inflammatory cytokines", "ILs", "serum amyloid protein A", "matrix metalloproteinase 3", "RANKL", "Glucose-6-phosphoisomerase", "Anti-keratin antibody", "1,25-Dihydroxyvitamin D3".

RESULTS

Indicators like MMPs, ILs, glucose-6-phosphate isomerase (GPI), anti-keratin antibody (AKA) and receptor activator of nuclear factor-κB ligand (RANKL) are the current hotspots in the efficacy research of RA. The present review suggests that ILs are highly expressed in the serum and synovial tissues of RA patients. By targeted inhibition of ILs with inhibitor application, precise RA treatment can be achieved.

CONCLUSIONS

Based on these results, it can be concluded that inflammatory factors have certain guiding significance in the diagnosis and efficacy evaluation of RA. However, the mechanisms of interactions among them are rather complex, which deserve further exploration.

Anlotinib attenuates experimental autoimmune encephalomyelitis mice model of multiple sclerosis via modulating the differentiation of Th17 and Treg cells

BACKGROUND

In multiple sclerosis (MS), the imbalance between T helper (Th)-17 cells and regulatory T (Treg) cells are critical in autoimmune central nervous system (CNS) inflammation and demyelination. Experimental autoimmune encephalomyelitis (EAE) is an established mouse MS model and simulates MS at diverse levels.

OBJECTIVES

This study aims at investigating the impact of anlotinib on the clinical severity of EAE and CD4⁺ T cell differentiation.

MATERIALS AND METHODS

EAE-induced mice were treated with water (control) or 6 mg/kg anlotinib by gavage daily. At the peak of EAE, histopathological examination and flow cytometry analysis of CNS-infiltrating CD4⁺ T cells were performed. In vitro differentiation of CD4⁺ T cells under different conditions was detected by flow cytometry and quantitative real-time PCR. Finally, the impacts of anlotinib on the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the transcription levels of key genes involved in Th17 and Treg differentiation were tested.

RESULTS

Anlotinib attenuated the clinical severity of EAE and changed the frequencies of CNS-infiltrating CD4⁺ T cell subsets. Anlotinib inhibited the differentiation of Th17 cells in vitro, decreased the phosphorylation of STAT3, and reduced the expression of Rorc. Anlotinib promoted the differentiation of Treg cells and upregulated the expression levels of CD39 and CD73.

DISCUSSION AND CONCLUSIONS

Anlotinib alleviated the symptoms of EAE via inhibiting the Th17 cell differentiation and promoting Treg cell differentiation. Our study provides new opportunities for the exploitation of anlotinib as a therapeutic agent for the treatment of MS.

TNF-α impairs EP4 signaling through the association of TRAF2-GRK2 in primary fibroblast-like synoviocytes

Our previous study showed that chronic treatment with tumor necrosis factor-α (TNF-α) decreased cAMP concentration in fibroblast-like synoviocytes (FLSs) of collagen-induced arthritis (CIA) rats. In this study we investigated how TNF-α impairs cAMP homeostasis, particularly clarifying the potential downstream molecules of TNF-α and prostaglandin receptor 4 (EP4) signaling that would interact with each other. Using a cAMP FRET biosensor PM-ICUE3, we demonstrated that TNF-α (20 ng/mL) blocked ONO-4819-triggered EP4 signaling, but not Butaprost-triggered EP2 signaling in normal rat FLSs. We showed that TNF-α (0.02-20 ng/mL) dose-dependently reduced EP4 membrane distribution in normal rat FLS. TNF-α significantly increased TNF receptor 2 (TNFR2) expression and stimulated proliferation in human FLS (hFLS) via ecruiting TNF receptor-associated factor 2 (TRAF2) to cell membrane. More interestingly, we revealed that TRAF2 interacted with G protein-coupled receptor kinase (GRK2) in the cytoplasm of primary hFLS and helped to bring GRK2 to cell membrane in response of TNF-α stimulation, the complex of TRAF2 and GRK2 then separated on the membrane, and translocated GRK2 induced the desensitization and internalization of EP4, leading to reduced production of intracellular cAMP. Silencing of TRAF2 by siRNA substantially diminished TRAF2-GRK2 interaction, blocked the translocation of GRK2, and resulted in upregulated expression of membrane EP4 and intracellular cAMP. In CIA rats, administration of paroxetine to inhibit GRK2 effectively improved the symptoms and clinic parameters with significantly reduced joint synovium inflammation and bone destruction. These results elucidate a novel form of cross-talk between TNFR (a cytokine receptor) and EP4 (a typical G protein-coupled receptor) signaling pathways. The interaction between TRAF2 and GRK2 may become a potential new drug target for the treatment of inflammatory diseases.

The Signaling Pathway of PGE2 and Its Regulatory Role in T Cell Differentiation

Prostaglandin E2 (PGE2) is a lipid mediator derived from the fatty acid arachidonic acid. As an essential inflammatory factor, PGE2 has a critical impact on immune regulation through the prostanoid E (EP) receptor pathway. T cells, including CD4+ and CD8+ T cell subsets, play crucial roles in the adaptive immune response. Previous studies have shown that PGE2 is involved in regulating CD4+ T cell differentiation and inflammatory cytokine production via the EP receptor pathway, thereby affecting the development of diseases mediated by CD4+ T cells. In this review, we summarize the signaling pathway of PGE2 and describe the relationship between PGE2 and T cell differentiation. Hence, this review may provide important evidence for immune therapies and may even promote the development of biomedicines.

Effect of resolvin D5 on T cell differentiation and osteoclastogenesis analyzed by lipid mediator profiling in the experimental arthritis

Resolvins, are specialized pro-resolving mediators (SPMs) derived from n-3 polyunsaturated fatty acids. They contribute actively to the resolution of inflammation, but little is known concerning their role in chronic inflammation, such as in rheumatoid arthritis (RA). Here, we performed lipid mediator (LM) profiling in tissues from the paws of SKG arthritic mice using lipid chromatography (LC)/mass spectrometry (MS)/MS-based LM metabololipidomics. We found elevated levels of SPMs including resolvin D5 (RvD5) in these tissues. Moreover, RvD5 levels were significantly correlated with arthritis disease activity. From experiments to assess the role of RvD5 in the pathology of RA, we concluded that RvD5 suppressed Th17 cell differentiation and facilitated regulatory T cell differentiation, as well as inhibiting CD4⁺ T cell proliferation. Furthermore, RvD5 attenuated osteoclast differentiation and interfered with osteoclastogenesis. Targeting the resolution of inflammation could be promising as a novel treatment for RA.

Molecular biochemical aspects of salt (sodium chloride) in inflammation and immune response with reference to hypertension and type 2 diabetes mellitus

Obesity, insulin resistance, type 2 diabetes mellitus (T2DM) and hypertension (HTN) are common that are associated with low-grade systemic inflammation. Diet, genetic factors, inflammation, and immunocytes and their cytokines play a role in their pathobiology. But the exact role of sodium, potassium, magnesium and other minerals, trace elements and vitamins in the pathogenesis of HTN and T2DM is not known. Recent studies showed that sodium and potassium can modulate oxidative stress, inflammation, alter the autonomic nervous system and induce dysfunction of the innate and adaptive immune responses in addition to their action on renin-angiotensin-aldosterone system. These actions of sodium, potassium and magnesium and other minerals, trace elements and vitamins are likely to be secondary to their action on pro-inflammatory cytokines IL-6, TNF-α and IL-17 and metabolism of essential fatty acids that may account for their involvement in the pathobiology of insulin resistance, T2DM, HTN and autoimmune diseases.

Transcriptional Profiles Reveal Deregulation of Lipid Metabolism and Inflammatory Pathways in Neurons Exposed to Palmitic Acid

The effects of the consumption of high-fat diets (HFD) have been studied to unravel the molecular pathways they are altering in order to understand the link between increased caloric intake, metabolic diseases, and the risk of cognitive dysfunction. The saturated fatty acid, palmitic acid (PA), is the main component of HFD and it has been found increased in the circulation of obese and diabetic people. In the central nervous system, PA has been associated with inflammatory responses in astrocytes, but the effects on neurons exposed to it have not been largely investigated. Given that PA affects a variety of metabolic pathways, we aimed to analyze the transcriptomic profile activated by this fatty acid to shed light on the mechanisms of neuronal dysfunction. In the current study, we profiled the transcriptome response after PA exposition at non-toxic doses in primary hippocampal neurons. Gene ontology and Reactome pathway analysis revealed a pattern of gene expression which is associated with inflammatory pathways, and importantly, with the activation of lipid metabolism that is considered not very active in neurons. Validation by quantitative RT-PCR (qRT-PCR) of Hmgcs2, Angptl4, Ugt8, and Rnf145 support the results obtained by RNAseq. Overall, these findings suggest that neurons are able to respond to saturated fatty acids changing the expression pattern of genes associated with inflammatory response and lipid utilization that may be involved in the neuronal damage associated with metabolic diseases.

Glaucocalyxin A suppresses inflammatory responses and induces apoptosis in TNF-a-induced human rheumatoid arthritis via modulation of the STAT3 pathway

The pathogenesis of rheumatoid arthritis (RA) is characterized by synoviocyte hyperplasia and proinflammatory cytokine secretion, as well as the destruction of cartilage and bone. Glaucocalyxin A (GLA) is an alkaloid derived from a Chinese medicinal plant that exhibits anti-inflammatory, anti-tumor and neuroprotective properties. We investigated the effects of GLA on RA-fibroblast-like synoviocytes (FLS cells), and collagen-induced arthritis (CIA), and further explored the underlying mechanisms. GLA inhibited TNF-a-induced RA-FLS proliferation, increased apoptotic ratios and upregulated levels of caspase-3, cleaved PARP, and Bax. GLA also inhibited the expression of IL-10, IL-1β, and IL-6 in vitro. Levels of p-STAT3 were downregulated in a dose-dependent manner. Over-expression of STAT3 partly neutralized the GLA-mediated elevation of caspase-3 and cleaved PARP levels as well as the downregulation of IL-10, IL-1B and IL-6 expression levels. This suggests that GLA inactivated the STAT3 pathway. Furthermore, the production of inflammatory cytokines in RA-FLS and a CIA rat model were inhibited effectively by GLA. Taken together, our data suggest that GLA is a potential long-term therapeutic agent for patients with RA.

Celastrol Regulates the Secretion of Interleukin-17 in Patients with Sympathetic Ophthalmia Through Signal Transducer and Activator of Transcription 3

Purpose: The excessive secretion of interleukin (IL)-17 contributes to the pathological process of sympathetic ophthalmia (SO). Celastrol is a naturally active product and exhibits an immunosuppressive effect. However, whether the supplementation of celastrol relieves SO remains unclear. Methods: The peripheral blood mononuclear cells (PBMCs) were extracted from the venous blood samples of 20 SO patients and 20 healthy controls, followed by stimulating with various concentrations of celastrol. The levels of IL-23 and IL-17 were measured by enzyme-linked immunosorbent assay and real-time polymerase chain reaction assay. The activation of the signal transducer and activator of transcription 3 (STAT3) in PBMCs of SO patients was detected by Western blot. Results: The levels of IL-23 and IL-17 in PBMCs isolated from SO patients were significantly increased compared with those in PBMCs isolated from healthy controls. Celastrol treatment inhibited the production of both IL-23 and IL-17 in PBMCs of SO patients in a dose-dependent manner. In PBMCs isolated from SO patients and healthy controls, the administration of recombinant human IL-23 (rIL-23) enhanced the production of IL-17, which was then suppressed by co-stimulation with celastrol. Also, celastrol treatment reduced rIL-23-induced phosphorylation of STAT3 in PBMCs isolated from SO patients. Conclusions: Celastrol can reduce the production of IL-17 in PBMCs of SO patients. The mechanism may be related to the reduction of IL-23 secretion, which in turn inhibits the phosphorylation of STAT3.

Electrophilic nitro-fatty acids suppress psoriasiform dermatitis: STAT3 inhibition as a contributory mechanism

Psoriasis is a chronic inflammatory skin disease with no cure. Although the origin of psoriasis and its underlying pathophysiology remain incompletely understood, inflammation is a central mediator of disease progression. In this regard, electrophilic nitro-fatty acids (NO₂–FAs) exert potent anti-inflammatory effects in several in vivo murine models of inflammatory diseases, such as chronic kidney disease and cardiovascular disease. To examine the therapeutic potential of NO₂–FAs on psoriasiform dermatitis, we employed multiple murine models of psoriasis. Our studies demonstrate that oral treatment with nitro oleic acid (OA-NO₂) has both preventative and therapeutic effects on psoriasiform inflammation. In line with this finding, oral OA-NO₂ downregulated the production of inflammatory cytokines in the skin. In vitro experiments demonstrate that OA-NO₂ decreased both basal IL-6 levels and IL-17A-induced expression of IL-6 in human dermal fibroblasts through the inhibition of NF-κB phosphorylation. Importantly, OA-NO₂ diminished STAT3 phosphorylation and nuclear translocation via nitroalkylation of STAT3, which inhibited keratinocyte proliferation. Overall, our results affirm the critical role of both NF-κB and STAT3 in the incitement of psoriasiform dermatitis and highlight the pharmacologic potential of small molecule nitroalkenes for the treatment of cutaneous inflammatory diseases, such as psoriasis.

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Oral OA-NO₂ has a therapeutic effect on inflammation in murine models of psoriasis.

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Cutaneous inflammatory cytokines are suppressed following oral OA-NO₂ treatment.

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OA-NO₂ decreases basal and IL-17A-induced IL-6 expression in vitro.

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OA-NO₂ diminishes STAT3 activation through nitroalkylation of STAT3.

miR-384-5p regulates inflammation in Candida albicans-induced acute lung injury by downregulating PGC1β and enhancing the activation of Candida albicans-triggered signaling pathways

Acute lung injury (ALI) is one of the most prevalent respiratory syndromes of excessive inflammatory reaction during lung infection. Candida albicans (C. albicans) infection is among the leading causes of ALI. MicroRNAs (miRNAs) regulate the expression of target mRNAs, including those involved in inflammatory processes, by binding to the 3'UTR. To date, the roles of miRNAs in C. albicans-induced ALI remain unclear. In this study, we investigated the role of miR-384-5p in C. albicans-induced ALI and its underlying molecular mechanism. RT-PCR, Western blot, ELISA, Myeloperoxidase (MPO) assay, microRNA target analysis, transient transfection, and luciferase reporter assay were utilized. In vivo study was conducted on mouse model. The expression of miR-384-5p was upregulated and positively correlated with inflammatory cytokine production in lung tissues and RAW264.7 and J774A.1 macrophages infected with C. albicans. The miR-384-5p inhibitor alleviated the inflammatory reaction induced by C. albicans. Target prediction analysis revealed that PGC1β was a target of miR-384-5p, which was further validated by the PGC1β 3'-UTR luciferase assay and the inverse correlation between the expression of miR-384-5p and PGC1β in C. albicans-infected ALI tissues and macrophages. Moreover, macrophages transfected with miR-384-5p mimic exhibited reduced levels of PGC1β. The suppression of the expression of PGC1β by C. albicans infection in the macrophages was abrogated by miR-384-5p inhibitor. Then, we demonstrated that PGC1β played an inhibitory role in C. albicans-induced production of inflammatory cytokines. Furthermore, suppression of miR-384-5p in macrophages inhibited the activation of the NF-κB, MAPK, and Akt signaling pathways triggered by C. albicans, but not the STAT3 pathway. These results demonstrate that miR-384-5p contributes to C. albicans-induced ALI at least in part by targeting PGC1β and enhancing the activation of the NF-κB, MAPK, and Akt inflammatory signaling pathways. Thus, targeting miR-384-5p might exert a protective effect on C. albicans-induced ALI.

Molecular mechanisms and clinical studies of iguratimod for the treatment of ankylosing spondylitis

Iguratimod (IGU) is a novel small molecule anti-rheumatic drug with the effect of non-steroidal anti-inflammatory drug and disease-modifying anti-rheumatic drug. IGU has various mechanisms of action, including inhibition of prostaglandin E2, tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17) production, inhibition of macrophage migration inhibitory factor (MIF)-induced proinflammatory effects, inhibition of osteoclastogenesis, and promotion of osteoblastic differentiation. Ankylosing spondylitis (AS) is the major subtype of spondyloarthritis that affects the axial skeleton, causing inflammatory back pain, which can lead to impairments in structure and function and a decrease in quality of life. Theories on pathogenesis of AS include misfolding of human leukocyte antigen-B27 during its assembly leading to endoplasmic reticulum stress and unfolded protein response (UPR). Activation of UPR genes results in release of TNF-α and IL-17, which have been shown to be important in the development of AS. In addition, current evidence suggests the importance of cyclooxygenase-2/prostaglandin E2 pathway and MIF in the pathogenesis of AS. Current drugs for the treatment of AS are limited and exploration of effective drugs is needed. IGU may be effective for the treatment of AS given that its mechanisms of action are closely related to the pathogenesis of AS. In fact, several small-scale clinical trials have shown the efficacy of IGU for the treatment of AS. This article reviews the molecular mechanisms of IGU that are related to the pathogenesis of AS and clinical trials of IGU for the treatment of AS, providing a reference for future clinical application of IGU for AS.

Immunological Mechanisms in Inflammation-Associated Colon Carcinogenesis

Patients with chronic inflammatory bowel diseases are at an increased risk of developing colitis-associated cancer (CAC). Chronic inflammation positively correlates with tumorigenesis. Similarly, the cumulative rate of incidence of developing CAC increases with prolonged colon inflammation. Immune signaling pathways, such as nuclear factor (NF)-κB, prostaglandin E2 (PGE2)/cyclooxygenase-2 (COX-2), interleukin (IL)-6/signal transducer and activator of transcription 3 (STAT3), and IL-23/T helper 17 cell (Th17), have been shown to promote CAC tumorigenesis. In addition, gut microbiota contributes to the development and progression of CAC. This review summarizes the signaling pathways involved in the pathogenesis following colon inflammation to understand the underlying molecular mechanisms in CAC tumorigenesis.

CD4+ CCR6+ T cells, but not γδ T cells, are important for the IL-23R-dependent progression of antigen-induced inflammatory arthritis in mice

IL‐23 plays an important role in the development of arthritis and the IL‐23 receptor (IL‐23R) is expressed on different types of T cells. However, it is not fully clear which IL‐23R⁺ T cells are critical in driving T cell‐mediated synovitis. We demonstrate, using knock‐in IL‐23R‐GFP reporter (IL‐23R^GFP/+) mice, that CD4⁺CCR6⁺ T cells and γδ T cells, but not CD8⁺ T cells, express the IL‐23R(GFP). During early arthritis, IL‐23R(GFP)⁺CD4⁺CCR6⁺ T cells, but not IL‐23R(GFP)⁺ γδ T cells, were present in the inflamed joints. IL‐23R^GFP/+ mice were bred as homozygotes to obtain IL‐23R^GFP/GFP (IL‐23R deficient/IL‐23R^−/−) mice, which express GFP under the IL‐23R promotor. Arthritis progression and joint damage were significantly milder in IL‐23R^−/− mice, which revealed less IL‐17A⁺ cells in their lymphoid tissues. Surprisingly, IL‐23R^−/− mice had increased numbers of IL‐23R(GFP)⁺CD4⁺CCR6⁺ and CCR7⁺CD4⁺CCR6⁺ T cells in their spleen compared to WT, and IL‐23 suppressed CCR7 expression in vitro. However, IL‐23R(GFP)⁺CD4⁺CCR6⁺ T cells were present in the synovium of IL‐23R^−/− mice at day 4. Finally, adoptive transfer experiments revealed that CD4⁺CCR6⁺ T cells and not γδ T cells drive arthritis progression. These data suggest that IL‐23R‐dependent T cell‐mediated synovitis is dependent on CD4⁺CCR6⁺ T cells and not on γδ T cells.

Beyond the TNF-α Inhibitors: New and Emerging Targeted Therapies for Patients with Axial Spondyloarthritis and their Relation to Pathophysiology

Axial spondyloarthritis (axSpA) is a complex disease that affects the joints and entheses of axial and peripheral joints, and is associated with inflammation in extra-articular sites such as the gut. Improved knowledge on genetics and immunology has improved treatment options with the availability of treatments targeting tumor necrosis factor-α (TNF-α) and interleukin (IL)-17. However, these agents do not provide clinical benefit for about 40% of patients, and additional therapeutic options are necessary. Theories on pathogenesis includes misfolding of HLA-B*27 during its assembly leading to endoplasmic reticulum stress and autophagy/unfolded protein response (UPR). HLA-B*27 may express free heavy chain on the cell surface, which activates innate immune receptors on T, natural killer, and myeloid cells with pro-inflammatory effects. Activation of UPR genes is associated with increased TNF-α, interleukin-23 (IL-23), IL-17, interferon-γ expression, and expansion of T helper (Th)-17 cells. Certain genotypes of endoplasmic reticulum aminopeptidase (ERAP) 1 and 2 are associated with ankylosing spondylitis (AS) and functionally interact with the HLA-B27 peptidome. Innate immune cells type 3, which express RORγt, regulate expression of IL-17 and IL-22 in T cells. Stimulation of gamma-delta T cells with IL-23 also induces IL-17. Mucosa-associated invariant T cells residing in the gut mucosa express IL-17 in AS patients after stimulation with IL-7. Prostaglandin E2 induces IL-17A independent of IL-23 via IL-1β and IL-6. The pathogenic role of gut inflammation, zonulin and microbiota, which has a different composition in AS patients, remains to be elucidated. This article also includes a comprehensive review on the mechanism of action and efficacy of the biological treatments currently approved for axSpA (TNF-α inhibitors and IL-17 inhibitors) and future targets for treatment (other IL-17 family member (s), Janus kinase, IL-23, and phosphodiesterase 4).

Candida albicans-induced acute lung injury through activating several inflammatory signaling pathways in mice

Candida albicans infection-induced acute lung injury is one of the most prevalent diseases in immunosuppressive individual. Nevertheless, the mechanism by which Candida albicans induced acute lung injury remains unclear. The present study investigated the mechanism by which Candida albicans induced acute lung injury in mice. Mice were randomly divided into four groups and intratracheally injected with 60 μl Candida albicans (10⁶ CFU) or normal saline. Half of the mice were sacrificed at 6 h after Candida albicans. The rest of the mice for survival test were observed until 7 d after Candida albicans. As expected, immunosuppression aggravated Candida albicans-induced acute lung injury and death in mice. Additionally, Candida albicans infection elevated mRNA levels of pro-inflammatory and chemokines in lungs and the levels of IL-6, IL-1β and IL-17 in serum. Further study showed that Candida albicans promoted nuclear translocation of NF-κB p50 and p65 subunits in pulmonary epithelial cells and interstitial cells. Candida albicans induced pulmonary p38, ERK1/2 and Akt phosphorylation in normal and immunosuppressive mice. Moreover, Candida albicans infection activated pulmonary STAT3 signaling in normal and immunosuppressive mice. Overall, these results suggest that Candida albicans induced acute lung injury and death may be through activating several inflammatory signaling pathways.

Ocular Manifestations of Rheumatoid Arthritis: Implications of Recent Clinical Trials

While rheumatoid arthritis (RA) typically presents with synovitis of the small and medium joints of the hands, ocular manifestations of the disease are generally overlooked and largely underdiagnosed. These complications usually present in longstanding RA population and occasionally represents the first manifestation of the disease and generally affect the anterior chamber of the eye, leading to keratoconjunctivitis sicca, episcleritis, scleritis, peripheral ulcerative keratitis and anterior uveitis. In this review, we present the current understanding of the pathophysiologic mechanisms for ocular disease in RA, including the role of oxidative stress, cytokine imbalance, chronic inflammation, vascular permeability, immune complex deposition and the role of T-cells as well as the contribution of tear hyperosmolarity among other factors. We also discuss the clinical presentation and diagnosis of each of the ocular disease entities highlighting the latest strategies in the management of this serious disorders that could potentially lead to blindness and the implications of recently completed and ongoing clinical trials in the field. While RA disease control is the cornerstone in the management of RA-associated ocular manifestations, early recognition of ocular pathology with prompt referral to ophthalmology is of paramount importance in order to prevent blindness and improve the quality of life in this patient population.