GPR43 activation enhances psoriasis-like inflammation through epidermal upregulation of IL-6 and dual oxidase 2 signaling in a murine model

Gut Microbiota-Derived 3-Hydroxybutyrate Blocks GPR43-Mediated IL6 Signaling to Ameliorate Radiation Proctopathy

Radiation proctopathy (RP) is a common complication of radiotherapy for pelvic malignancies with high incidence. RP accompanies by microbial dysbiosis. However, how the gut microbiota affects the disease remains unclear. Here, metabolomics reveals that the fecal and serous concentrations of microbiota-derived 3-hydroxybutyrate (3HB) are significantly reduced in RP mice and radiotherapeutic patients. Moreover, the concentration of 3HB is negatively associated with the expression of proinflammatory IL6 that is increased along with the severity of radiation damage. 3HB treatment significantly downregulates IL6 expression and alleviates IL6-mediated radiation damage. Irradiated cell-fecal microbiota co-culture experiments and in vivo assays show that such a radioprotection of 3HB is mediated by GPR43. Microbiome analysis reveals that radiation leads to a distinct bacterial community compared to untreated controls, in which Akkermansia muciniphila is significantly reduced in RP mice and radiotherapeutic patients and is associated with lower 3HB concentration. Gavage of A. muciniphila significantly increases 3HB concentration, downregulates GPR43 and IL6 expression, and ameliorates radiation damage. Collectively, these results demonstrate that the gut microbiota, including A. muciniphila, induce higher concentrations of 3HB to block GPR43-mediated IL6 signaling, thereby conferring radioprotection. The findings reveal a novel implication of the gut-immune axis in radiation pathophysiology, with potential therapeutic applications.

Effect of stearyl alcohol on imiquimod-induced psoriasis-like skin inflammation in mice

Psoriasis is a chronic inflammatory skin disease. Topical medicines are the preferred treatment for mild to moderate psoriasis, but the effect of excipients used in semi-solid preparations on psoriasis-like skin inflammation is not fully understood. In the present study, we investigated the effect of stearyl alcohol, a commonly used excipient, on imiquimod (IMQ)-induced psoriasis-like skin inflammation in mice. Psoriasis-like skin inflammation was induced by topical IMQ treatment on the back of mice. Skin lesion severity was evaluated by using psoriasis area and severity index (PASI) scores. The skin sections were stained by haematoxylin-eosin and immunohistochemistry. Stearyl alcohol (20% in vaseline) treatment significantly reduced the IMQ-induced increase of PASI scores and epidermal thickness in mice. IMQ treatment increased the number of Ki67- and proliferating cell nuclear antigen (PCNA)-positive cells in the skin, and the increases were inhibited by stearyl alcohol (20% in vaseline) treatment. Stearyl alcohol treatment (1%, 5%, 10% in vaseline) dose-dependently ameliorated IMQ-induced increase of PASI scores and epidermal thickness in mice. Hexadecanol (20% in vaseline), stearic acid (20% in vaseline) and vaseline treatment had no significant effect on IMQ-induced psoriasis-like skin inflammation in mice. In conclusion, stearyl alcohol has the effect of improving IMQ-induced psoriasis-like skin inflammation in mice.

Attenuated effects of topical vinpocetine in an imiquimod-induced mouse model of psoriasis

Psoriasis is an uncontrolled, long-lasting inflammatory dermatosis distinguished by thickened, erythematous, and flaky skin lesions. Massive amounts of inflammatory cytokines are produced when immune system imbalances are driven by genetic and environmental triggers. Vinpocetine (VNP), a man-made analogue of the compound vincamine found in the dwarf periwinkle herb, has robust anti-inflammatory, immunomodulatory, and anti-oxidative effects; alleviates the epidermal penetration of immune cells, such as eosinophils and neutrophils; and abolishes the generation of pro-inflammatory molecules.

Objective

This study was aimed at exploring the effects of long-term topical VNP, both alone and co-administered with clobetasol propionate, in an imiquimod-induced mouse model of psoriasiform dermatitis.

Methods

The study protocol consisted of 48 Swiss albino mice, randomly divided into six groups of eight mice each. In group I, petroleum jelly was administered daily for 8 days. In group II, imiquimod was administered topically at 62.5 mg daily for 8 days. In groups III, VI, V, and VI, 0.05% clobetasol propionate, 1% VNP, 3% VNP, and 3% VNP plus 0.05% clobetasol were administered topically for an additional 8 days after the induction, thus resulting in a total trial length of 16 days.

Results

Topical VNP at various doses alleviated the severity of imiquimod-induced psoriatic lesions-including erythema, silvery-white scaling, and thickening-and reversed the histopathological abnormalities. Moreover, imiquimod-exposed animals treated with VNP showed markedly diminished concentrations of inflammatory biomarkers, including tumour necrosis factor-α, interleukin (IL)-8, IL-17A, IL-23, IL-37, nuclear factor-kappa B (NF-κB), and transforming growth factor-β1.

Conclusion

This research provides new evidence that VNP, alone and in combination with clobetasol, may serve as a potential adjuvant for long-term management of autoimmune and autoinflammatory skin diseases, particularly psoriasis, by attenuating psoriatic lesion severity, suppressing cytokine generation, and limiting NF-κB-mediated inflammation.

The ameliorative effects of topical gemifloxacin alone or in combination with clobetasol propionate on imiquimod-induced model of psoriasis in mice

Psoriasis is a lifelong immune-driven skin condition characterized by excessive epidermal overgrowth and inflammatory cell infiltration. Gemifloxacin is a fourth-generation fluoroquinolone with improved immunomodulatory and anti-inflammatory properties that are believed to possess an attractive role in psoriasis via suppressing the production of cytokines, chemokines, and eosinophil and neutrophil chemotaxis. The aim of this research is to investigate the ameliorative effects of prolonged topical gemifloxacin (GMF) alone and combined with clobetasol propionate (CLO) on an imiquimod (IMQ)-induced mouse model of psoriasis. Forty-eight Swiss albino mice were divided into six groups of eight. All groups except the negative controls got 62.5 mg of IMQ 5% topically for 8 days. Mice in the control group (controls) got Vaseline instead. Following the induction in the IMQ 5% group, mice in treatment groups CLO 0.05, GMF 1%, GMF 3%, and CLO + GMF obtained clobetasol propionate 0.05%, GMF 1% and 3%, and a combination of both, respectively, for an additional 8 days, rendering the experiment 16 days long. Our results revealed that gemifloxacin alleviated erythematous, thickened, and scaly psoriatic lesions and inhibited the tissue level of inflammatory cytokines, including interleukin (IL)-8, IL-17A, IL-23, tumor necrosis factor-α (TNF-α), and transforming growth factor-β1 (TGF-β1). The anti-inflammatory effect also occurred by hindering nuclear factor-kappa B (NF-κB) signaling and reversing histopathological problems. Gemifloxacin acts effectively in mitigating psoriasis-associated lesions and restricting NF-κB-mediated inflammation, recommending gemifloxacin as a promising adjuvant candidate for additional studies on the long-term treatment of autoimmune and autoinflammatory dermatoses like psoriasis.

Glycyrol Prevents the Progression of Psoriasis-like Skin Inflammation via Immunosuppressive and Anti-Inflammatory Actions

Glycyrol (GC) is one natural active product. Imiquimod-induced psoriasis-like Balb/c mouse models were established. The model mice were intraperitoneally injected with cyclosporine A (CsA) and GC for 8 days followed by a series of biological detections. GC had little toxicity according to the levels of peripheral blood cells, hemoglobin, blood urea nitrogen (BUN), and serum creatinine (CRE), while CsA significantly increased the levels of BUN and CRE. GC decreased the splenic index and reduced the expressions of IL-6, IL-23, and CXCL-3 in the model mice and IL-6, CXCL-1, and CXCL-2 in the inflammatory HaCaT cells. The half inhibition concentration (IC50) of GC on HaCaT cells was 29.72 μmol/L, resulting in improved apoptosis, enhanced expressions of p21, BAX, and BIK, and reduced expressions of BCL-2. GC is an immunosuppressive agent against psoriasis-like symptoms by anti-inflammatory effects, which provides a strategy for the discovery of anti-psoriatic natural products.

A review of the auditory-gut-brain axis

Hearing loss places a substantial burden on medical resources across the world and impacts quality of life for those affected. Further, it can occur peripherally and/or centrally. With many possible causes of hearing loss, there is scope for investigating the underlying mechanisms involved. Various signaling pathways connecting gut microbes and the brain (the gut-brain axis) have been identified and well established in a variety of diseases and disorders. However, the role of these pathways in providing links to other parts of the body has not been explored in much depth. Therefore, the aim of this review is to explore potential underlying mechanisms that connect the auditory system to the gut-brain axis. Using select keywords in PubMed, and additional hand-searching in google scholar, relevant studies were identified. In this review we summarize the key players in the auditory-gut-brain axis under four subheadings: anatomical, extracellular, immune and dietary. Firstly, we identify important anatomical structures in the auditory-gut-brain axis, particularly highlighting a direct connection provided by the vagus nerve. Leading on from this we discuss several extracellular signaling pathways which might connect the ear, gut and brain. A link is established between inflammatory responses in the ear and gut microbiome-altering interventions, highlighting a contribution of the immune system. Finally, we discuss the contribution of diet to the auditory-gut-brain axis. Based on the reviewed literature, we propose numerous possible key players connecting the auditory system to the gut-brain axis. In the future, a more thorough investigation of these key players in animal models and human research may provide insight and assist in developing effective interventions for treating hearing loss.

d-mannose blocks the interaction between keratinocytes and Th17 cells to alleviate psoriasis by inhibiting HIF-1α/CCL20 in mice

Psoriasis is an autoimmune chronic inflammatory skin disease with an unclear pathogenesis that is difficult to cure, causing serious physical and mental burdens for patients. Previous research showed that a mutually reinforcing vicious cycle caused by keratinocytes (KC) and a variety of immune cells plays an important role in psoriatic inflammation. d-Mannose, a widely distributed metabolite in the body, has been found to treat several metabolic diseases, but its impact on psoriasis remains unknown. Our study aims to investigate the effects of d-mannose on psoriasis and its specific mechanism. Here, we found that d-mannose alleviates psoriasis in mice both as oral and topical agents. Specifically, d-mannose down-regulated the expression of hypoxia-inducible factor 1A(HIF-1α) and inhibited the expression of chemokine CCL20 in keratinocytes, thereby inhibiting the local infiltration of Th17 cells and breaking the cycle of keratinocytes-Th17 cells. Overall, our study indicates that d-mannose alleviates cutaneous inflammation in psoriasis by inhibiting the HIF-1α/CCL20/Th17 cells axis, and d-mannose has the potential to be used as an oral and topical agent in the treatment of psoriasis.

Targeting Nrf2 with 3 H-1,2-dithiole-3-thione to moderate OXPHOS-driven oxidative stress attenuates IL-17A-induced psoriasis

Psoriasis, a chronic autoimmune disease characterized by the hyperproliferation of keratinocytes in the epidermis and parakeratosis, significantly impacts quality of life. Interleukin (IL)- 17A dominates the pathogenesis of psoriasis and facilitates reactive oxygen species (ROS) accumulation, which exacerbates local psoriatic lesions. Biologic treatment provides remarkable clinical efficacy, but its high cost and unignorable side effects limit its applications. 3 H-1,2-Dithiole-3-thione (D3T) possesses compelling antioxidative capacities against several diseases through the nuclear factor erythroid 2-related factor 2 (Nrf2) cascade. Hence, we aimed to evaluate the effect and mechanism of D3T in psoriasis. We found that D3T attenuates skin thickening and scaling by inhibiting IL-17A-secreting γδT cells in imiquimod (IMQ)-induced psoriatic mice. Interleukin-17A markedly enhanced IL-6 and IL-8 expression, lipid peroxidation, the contents of nitric oxide and hydrogen peroxide, oxidative phosphorylation and the MAPK/NF-κB pathways in keratinocytes. IL-17A also inhibited the Nrf2-NQO1-HO-1 axis and the activities of superoxide dismutase and glutathione peroxidase. D3T significantly reversed these parameters in IL-17A-treated keratinocytes. ML-385, a Nrf2 neutralizer, failed to improve D3T-induced anti-inflammatory and antioxidative effects in IL-17A-treated keratinocytes. We conclude that targeting Nrf2 with D3T to diminish oxidative and inflammatory damage in keratinocytes may attenuate psoriasis.

The role of short-chain fatty acids in inflammatory skin diseases

Short-chain fatty acids (SCFAs) are metabolites of gut microbes that can modulate the host inflammatory response, and contribute to health and homeostasis. Since the introduction of the gut-skin axis concept, the link between SCFAs and inflammatory skin diseases has attracted considerable attention. In this review, we have summarized the literature on the role of SCFAs in skin inflammation, and the correlation between SCFAs and inflammatory skin diseases, especially atopic dermatitis, urticaria, and psoriasis. Studies show that SCFAs are signaling factors in the gut-skin axis and can alleviate skin inflammation. The information presented in this review provides new insights into the molecular mechanisms driving gut-skin axis regulation, along with possible pathways that can be targeted for the treatment and prevention of inflammatory skin diseases.

Neuroblast Differentiation-Associated Protein Derived Polypeptides: AHNAK(5758-5775) Induces Inflammation by Activating Mast Cells via ST2

Psoriasis is a chronic inflammatory skin disease. Mast cells are significantly increased and activated in psoriatic lesions and are involved in psoriatic inflammation. Some endogenous substances can interact with the surface receptors of mast cells and initiate the release of downstream cytokines that participate in inflammatory reactions. Neuroblast differentiation-associated protein (AHNAK) is mainly expressed in the skin, esophagus, kidney, and other organs and participates in various biological processes in the human body. AHNAK and its derived peptides have been reported to be involved in the activation of mast cells and other immune processes. This study aimed to investigate whether AHNAK (5758-5775), a neuroblast differentiation-associated protein-derived polypeptide, could be considered a new endogenous substance in psoriasis patients, which activates mast cells and induces the skin inflammatory response contributing to psoriasis. Wild-type mice were treated with AHNAK(5758-5775) to observe the infiltration of inflammatory cells in the skin and cytokine release in vivo. The release of inflammatory mediators by mouse primary mast cells and the laboratory of allergic disease 2 (LAD2) human mast cells was measured in vitro. Molecular docking analysis, molecular dynamics simulation, and siRNA transfection were used to identify the receptor of AHNAK(5758-5775). AHNAK(5758-5775) could cause skin inflammation and cytokine release in wild-type mice and activated mast cells in vitro. Moreover, suppression of tumorigenicity 2 (ST2) might be a key receptor mediating AHNAK(5758-5775)'s effect on mast cells and cytokine release. We propose a novel polypeptide, AHNAK(5758-5775), which induces an inflammatory reaction and participates in the occurrence and development of psoriasis by activating mast cells.

Trichinella pseudospiralis-secreted 53 kDa protein ameliorates imiquimod-induced psoriasis by inhibiting the IL-23/IL-17 axis in mice

Trichinella infection can experimentally ameliorate many autoimmune diseases. However, the immune mechanism of the amelioration and the identification of corresponding Trichinella-derived molecule(s) are still not fully elucidated. Fifty-three kDa excretory-secretory (ES) protein from Trichinella pseudospiralis (Tpp53) is a molecule like TsP53 reported as a protein exerting immune-inhibitory effect in T. spiralis. In this study, we investigated the immunomodulatory effect of Tpp53 using imiquimod (IMQ)-induced psoriasis-like dermatitis model, which is a mouse model of autoimmune disease with the pathogenic interleukin 17 (IL-17) producing CD4⁺ T cells (Th17) via IL-23/IL17 axis. Administrating the recombinant Tpp53 (rTpp53) mixed with IMQ cream on the skin of mice ameliorated psoriatic lesions, as revealed by the improvement of erythema, scaling, skin thickening, epidermis hyperplasia and parakeratosis, thickening of acanthosis cell layer, epidermal extension of dermis, less infiltration of inflammatory cells, and decreased expression of inflammatory marker. The increased expression of the factors related to the IL-23/IL-17 axis, including IL-17A, IL-6, Il17F and Il23a, in the skins of IMQ-treated mice was inhibited by rTpp53 treatment. Moreover, the expression of activated keratinocyte-produced cytokines, chemokines, and antimicrobial peptides in the skin was also down-regulated in rTpp53-treated IMQ-treated mice. Co-culture of splenocytes with rTpp53 inhibited IL-17A and treatment of macrophages with rTpp53 reduced IL-6 production. Overall, our study revealed that the Trichinella-secreted 53 kDa ES protein could ameliorate IMQ-induced psoriasis by inhibiting the IL-23/IL-17 axis, suggesting that Tpp53 might involve in regulating host Th17 for immune evasion and have an alternative potential for psoriasis therapy.

Targeting neuroinflammation as a preventive and therapeutic approach for perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PND) is a common postoperative complication associated with regional or general anesthesia and surgery. Growing evidence in both patient and animal models of PND suggested that neuroinflammation plays a critical role in the development and progression of this problem, therefore, mounting efforts have been made to develop novel therapeutic approaches for PND by targeting specific factors or steps alongside the neuroinflammation. Multiple studies have shown that perioperative anti-neuroinflammatory strategies via administering pharmacologic agents or performing nonpharmacologic approaches exert benefits in the prevention and management of PND, although more clinical evidence is urgently needed to testify or confirm these results. Furthermore, long-term effects and outcomes with respect to cognitive functions and side effects are needed to be observed. In this review, we discuss recent preclinical and clinical studies published within a decade as potential preventive and therapeutic approaches targeting neuroinflammation for PND.

Advances in the modulation of ROS and transdermal administration for anti-psoriatic nanotherapies

Reactive oxygen species (ROS) at supraphysiological concentration have a determinate role in contributing to immuno-metabolic disorders in the epithelial immune microenvironment (EIME) of psoriatic lesions. With an exclusive focus on the gene-oxidative stress environment interaction in the EIME, a comprehensive strategy based on ROS-regulating nanomedicines is greatly anticipated to become the mainstay of anti-psoriasis treatment. This potential therapeutic modality could inhibit the acceleration of psoriasis via remodeling the redox equilibrium and reshaping the EIME. Herein, we present a marked overview of the current progress in the pathomechanisms of psoriasis, with particular concerns on the potential pathogenic role of ROS, which significantly dysregulates redox metabolism of keratinocytes (KCs) and skin-resident or -infiltrating cells. Meanwhile, the emergence of versatile nanomaterial-guided evolution for transdermal drug delivery has been attractive for the percutaneous administration of antipsoriatic therapies in recent years. We emphasize the underlying molecular mechanism of ROS-based nanoreactors for improved therapeutic outcomes against psoriasis and summarize up-to-date progress relating to the advantages and limitations of nanotherapeutic application for transdermal administration, as well as update an insight into potential future directions for nanotherapies in ROS-related skin diseases.

A randomized, double-blind phase III study to demonstrate the clinical similarity of biosimilar SCT630 to reference adalimumab in Chinese patients with moderate to severe plaque psoriasis

INTRODUCTION

This phase III study aimed to compare the efficacy, safety, and immunogenicity of SCT630 with the reference adalimumab.

METHODS

A total of 367 Chinese patients with moderate-to-severe plaque psoriasis were randomly assigned to receive 80 mg of SCT630 or adalimumab subcutaneously at week 1, 40 mg at week 2, then 40 mg biweekly. At week 16, those with 50 % or more improvement in psoriasis area and severity index (PASI) were eligible to enter an extension period up to week 52. Patients on SCT630 continued the same treatment, whereas patients receiving adalimumab were re-randomized at a ratio of 1:1 to adalimumab or SCT630 group. The primary endpoint was percentage improvement in PASI at week 16. Other endpoints included PASI 50/75/90/100, Physician's Global Assessment, Dermatology Life Quality Index, safety, and immunogenicity.

RESULTS

PASI improvement at week 16 was 85.07 % for SCT630 and 84.82 % for adalimumab. The mean difference (3.10 %, 95 % CI: -1.875 %, 8.066 %) was within the equivalence interval. Other efficacy endpoints, safety and immunogenicity profiles were similar across the two groups. There were no safety or immunogenicity difference between switched/continued groups.

CONCLUSION

This phase III study demonstrated the equivalences in efficacy, safety and immunogenicity of SCT630 to adalimumab in patients with moderate to severe psoriasis.

Dimeric translationally controlled tumor protein-binding peptide 2 attenuates imiquimod-induced psoriatic inflammation through induction of regulatory T cells

Psoriasis is a chronic skin inflammation caused by a dysfunctional immune system, which causes systemic inflammation in various organs and tissues. Due to the risk of systemic inflammation and recurrence of psoriasis, it is important to identify the critical targets in the pathogenesis of psoriasis and develop targeted therapeutics. Dimerized translationally controlled tumor protein (dTCTP) promotes immune cell activation as a pro-inflammatory cytokine and plays a role in developing allergic diseases such as asthma and rhinitis. Here, we sought to explore whether dTCTP and its inhibition contributed to the development and control of imiquimod (IMQ)-induced psoriasis. Topical application of IMQ inflamed the skin of the back and ear, increased inflammatory cytokines, and decreased regulatory T cell markers. Interestingly, TCTP was significantly increased in inflamed skin and immune cells such as T cells, B cells, and macrophages after IMQ treatment and was secreted into the serum to undergo dimerization. Extracellular dTCTP treatment selectively suppressed regulatory T (Treg) cells, not other effector T helper (Th) cells, and increased M1 macrophages. Moreover, dTCTP-binding peptide 2 (dTBP2), a dTCTP inhibitor peptide, effectively attenuated the systemic inflammatory responses, including Th17 cell response, and alleviated psoriatic skin inflammation. dTBP2 blocked dTCTP-mediated Treg suppression and stimulated the expression of Treg cell markers in the spleen and inflammatory skin lesions. These results suggest that dTCTP dysregulated immune balance through Treg suppression in psoriatic inflammation and that functional inhibition of dTCTP by dTBP2 maintained immune homeostasis and attenuated inflammatory skin diseases by expanding Treg cells.

Sprouty1 exerts a preventive effect on the initiation of psoriasis by inhibiting innate immune antimicrobial peptide cathelicidin and immunocytes

Objectives

Psoriasis is an immune‐mediated skin disease dominated by the cutaneous immune system. Keratinocytes have been considered important triggers that initiate psoriasis. The key molecules and events of keratinocytes that link the innate immune system in psoriasis must be investigated in more detail. Human psoriasis skin and primary human keratinocyte were detected in vitro. Epidermis specific transgenic mouse strain (Krt14‐Sprouty1 tg) was used to further investigate psoriasis‐like skin inflammation in vivo.

Materials and Methods

Bulk RNA sequencing of primary human keratinocyte screened differentially expressed genes, which was confirmed by quantitative real time PCR and Western Blot (WB). Moreover, we concomitantly reviewed open‐accessed published RNAseq datasets of human psoriatic skin from GEO database. Immunohistochemical staining and immunofluorescence were used to detect Sprouty1 (SPRY1) expression in human psoriatic skin with and without anti‐psoriasis treatments. Krt14‐Sprouty1 tg was used to further investigate psoriasis‐like skin inflammation, and followed by Hematoxylin and Eosin (HE) Staining, enzyme linked immunosorbent assay (ELISA), Western Blot and flow cytometry.

Results

Our data showed that Sprouty1 was decreased in psoriatic skin and keratinocytes. In imiquimod‐induced psoriasis‐like skin inflammation, the production of cathelicidin (camp/LL37) was inhibited by suppressing signal transducer and activator of transcription3 (Stat3) activation when Sprouty1 overexpressed in mouse epidermal keratinocytes. Moreover, CD11b+CCR2+ dendritic cells, IL‐17A+ γδT cells, and Ly6C+ CD11c+ monocyte‐derived dendritic cells were decreased in Krt14‐Sprouty1 tg (STG) imiquimod‐induced cutaneous inflammation.

Conclusions

These findings indicate that Sprouty1 expressed in keratinocytes has a suppressive role in imiquimod‐induced skin inflammation mediated by inhibiting the production of cathelicidin. Collectively, Sprouty1 plays a preventive role in psoriatic skin. Our data provide new evidence for the pathogenesis of psoriatic keratinocytes, and the link cutaneous innate immunity, that indicated Sprouty1 is a potential novel therapeutic target.

Anti-IL-17A ssDNA aptamer ameliorated psoriasis skin lesions in the imiquimod-induced psoriasis mouse model

OBJECTIVES

IL-17 is an important player in the psoriasis pathogenesis, which recruits inflammatory cells to the psoriatic lesions, induced keratinocyte proliferation and plaque formation. Three monoclonal antibodies that block IL-17 have been approved for psoriasis treatment in the last decade. Compared to monoclonal antibodies, aptamers which are single-stranded DNA or RNA, bind with high affinity to proteins or other molecules and are more cost-effective. We previously showed that M2 and M7 anti-IL17A ssDNA aptamers could block IL-17 in vitro. The current study evaluated the therapeutic effects of M2 and M7 anti-IL17A ssDNA aptamers in the imiquimod (IMQ)-induced psoriasis mouse model.

METHODS

IMQ cream and Vaseline (Vas) were administered on the back skin of C57BL/6 mice as IMQ-induced psoriasis and Vas control groups, respectively. In addition, hydrogel-containing aptamers were topically administered on the back skin of the mice, 10 min before IMQ treatment. Psoriatic lesions were evaluated by histology, clinical factors, and psoriasis area severity index (PASI) score. The mRNA expression levels of inflammatory factors, including IL-17A, IL-1β, and S100a9, were assessed with quantitative reverse transcriptase-polymerase chain reaction in the mice back skin.

RESULTS

Application of anti-IL-17A aptamers significantly ameliorated IMQ-induced keratinocyte proliferation, psoriatic lesions cumulative PASI score, IL-17A, IL-β, and S100a9 inflammatory factors mRNA expression levels (p < 0.05).

CONCLUSION

According to our results, it seems that M2 in high concentration and M7 in low concentration can be appropriate candidates to alleviate psoriasis lesions.

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Alleviate Psoriasis-like Skin Inflammation

Immunomodulatory effects of mesenchymal stem cells (MSCs) in inflammatory diseases, including psoriasis, are well documented. However, the role of MSC-derived exosomes (MSCs-Exo) in psoriasis-like skin inflammation remains largely unknown. This study aimed to investigate whether MSCs-Exo play a regulatory role in psoriasis-like skin inflammation. We found that subcutaneous injection of human umbilical cord MSCs-Exo (hucMSCs-Exo) significantly suppressed the proliferation of epidermis and reduced Psoriasis Area and Severity Index (PASI) scores in imiquimod (IMQ)-induced mice. hucMSCs-Exo also reduced the expression of interleukin (IL)-17, IL-23, and chemokine C-C-motif ligand 20 (CCL20) and inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) in the skin of IMQ-induced mice and in human keratinocyte (HaCaT) cells. In addition, co-cultured with hucMSCs-Exo in vitro, the maturation and activation of dendritic cells (DCs) were suppressed, and the expression level of IL-23 was decreased. These results indicate that hucMSCs-Exo can effectively ameliorate psoriasis-like skin inflammation in mice by regulating the expression of IL-23 and IL-17, and inhibiting the maturation and activation of DCs. Our data offer a promising therapeutic approach for psoriasis by leveraging the immunomodulatory effects of hucMSCs-Exo.

Short-Chain Fatty Acid and FFAR2 Activation - A New Option for Treating Infections?

The human innate immune system is equipped with multiple mechanisms to detect microbe-associated molecular patterns (MAMPs) to fight bacterial infections. The metabolite short-chain fatty acids (SCFAs) acetate, propionate and butyrate are released by multiple bacteria or are food ingredients. SCFA production, especially acetate production, is usually essential for bacteria, and knockout of pathways involved in acetate production strongly impairs bacterial fitness. Because host organisms use SCFAs as MAMPs and alter immune reactions in response to SCFAs, interventions that modulate SCFA levels can be a new strategy for infection control. The interaction between SCFAs and host cells has been primarily investigated in the intestinal lumen because of the high local levels of SCFAs released by bacterial microbiome members. However, members of not only the intestinal microbiome but also the skin microbiome produce SCFAs, which are known ligands of the seven-transmembrane G-protein-coupled receptor FFAR2. In addition to enterocytes, FFAR2 is expressed on other human cell types, including leukocytes, especially neutrophils. This finding is in line with other research that determined that targeted activation of FFAR2 diminishes susceptibility toward various types of infection by bacteria such as Klebsiella pneumonia, Citrobacter rodentium, and Staphylococcus aureus but also by viruses such as respiratory syncytial and influenza viruses. Thus, our immune system appears to be able to use FFAR2-dependent detection of SCFAs for perceiving and even averting severe infections. We summarize recent advances in understanding the role of SCFAs and FFAR2 in various infection types and propose the manipulation of this receptor as an additional therapeutic strategy to fight infections.

Novel archetype in psoriasis management bridging molecular dynamics in exploring novel therapies

Psoriasis is an autoimmune chronic inflammatory condition of skin affecting 125 million populaces around the globe. It is implicated as a result of multifaceted phenomena involving various cell and subcell activities with the aid of numerous cellular and molecular components including signaling aisle and regulatory proteins owing to the development of such hyperproliferative dermatological conditions. This involves a deeply complex and conflicting pathology owing to genetic and immunological deviations resulting from the unusual presentation of different signaling pathways and regulatory proteins. Explorations of these biomarkers and intervention of molecular and cellular processes in psoriasis are yet to be investigated and could be an exceptional aspect for understanding pathology with successful targeting of disease. In the presented study, we have integrated molecular insights, including signaling molecules, pathways, and proteins implicated in pathogenesis, and we have attempted to link this knowledge to the targeting of these phenomena in order to manage the conditions precisely. Further, therapeutic delivery approaches for targeting distinct layers of skin have also been investigated based on the application of different nanocarriers for successful psoriasis treatment.

Repurposing anthelmintic praziquantel to treat psoriasis

BACKGROUND AND PURPOSE

The anthelmintic drug praziquantel (PZQ) has been used as a standard treatment for schistosomiasis for over 40 years. This study aimed to repurpose PZQ to treat psoriasis.

EXPERIMENTAL APPROACH

Psoriasis-like skin inflammation was induced in mice by topical application of imiquimod or intradermal injection of recombinant IL-23. PZQ was either orally or topically administrated during the psoriasis induction period.

KEY RESULTS

Mice treated with either oral or topical PZQ exhibited markedly improved psoriasiform skin symptoms when compared to control mice, as judged by disease severity score, epidermal thickening, inflammatory cell infiltration, and spleen size. Flow cytometric analysis of infiltrating immune cells from mouse skin displayed reduced infiltration of Th17 cells. In vitro experiments revealed that PZQ inhibited signal transducer and activator of transcription 3 (STAT3) phosphorylation and RORγt expression in splenic CD4⁺ T cells. PZQ also decreased STAT3 phosphorylation in HEK-A/F cells. Downregulation of STAT3 phosphorylation in these cells accounts for the decreased number of Th17 cells and keratinocytes.

CONCLUSION AND IMPLICATIONS

These results amount to the first preclinical evidence that PZQ may effectively treat psoriasis, and suggest that PZQ alleviates symptoms in mice by inhibiting STAT3 phosphorylation, thereby suppressing Th17 immune responses.

Pharmacological Inhibition of STAT3 by Stattic Ameliorates Clinical Symptoms and Reduces Autoinflammation in Myeloid, Lymphoid, and Neuronal Tissue Compartments in Relapsing-Remitting Model of Experimental Autoimmune Encephalomyelitis in SJL/J Mice

Multiple sclerosis (MS) is an immune-mediated inflammatory disease that leads to demyelination and neuronal loss in the central nervous system. Immune cells of lymphoid and myeloid origin play a significant role in the initiation and amplification of neuronal inflammation in MS. STAT3 signaling plays a pivotal role in both myeloid and lymphoid immune cells, such as neutrophils and CD4+ T cells, through regulation of their inflammatory potential. Dysregulation in STAT3 signaling in myeloid and lymphoid cell compartments has been reported in MS. In this report, we attempted to investigate the effect of a small molecular inhibitor of STAT3, i.e., Stattic, in a relapsing–remitting (RR) model of experimental autoimmune encephalomyelitis (EAE). The effect of Stattic was investigated for clinical features, oxidative stress parameters, and Th17-related signaling in both the periphery and brain of SJL/J mice. Our data report that p-STAT3 expression is elevated in granulocytes, CD4+ T cells, and brain tissue in myelin proteolipid protein (PLP)-immunized SJL/J mice, which is associated with the presence of clinical symptoms and upregulation of inflammatory markers in these cells/tissues. Treatment with Stattic leads to the amelioration of disease symptoms and attenuation of inflammatory markers in neutrophils (iNOS/nitrotyrosine/IL-1β), CD4+ T cells (IL-17A/IL-23R), and brain tissue (IL-17A/iNOS/IL-1β/MPO activity/lipid peroxides) in mice with EAE. These data suggest that the blockade of STAT3 signaling in cells of lymphoid and myeloid origin may cause the attenuation of systemic and neuronal inflammation, which could be responsible for the amelioration of disease symptoms in an RR model of EAE. Therefore, pharmacological inhibition of STAT3 in RRMS could be a potential therapeutic strategy.

Optimization of psoriasis mouse models

INTRODUCTION

Psoriasis, is a common, chronic, autoimmune, inflammatory, relapsing disease, which would benefit from reliable and human-relevant animal models to test drugs pre-clinically and to understand their mechanism of action. Because of its ease of use, convenience and low cost, the imiquimod (IMQ)-induced psoriasis-like model is widely utilized; however, it is not known whether all mouse strains are equivalent and if the hairless mouse is appropriate, so that the imiquimod model can be further optimized.

METHODS

Under similar experimental conditions, common mouse strains (BALB/c, C57BL/6J, and ApoE) and a new hairless strain (ApoE/SKH-hr2) as well as several inducers (IMQ, IMQ + acetic acid (AcOH) topical and IMQ + AcOH systemic) were compared by clinical, histopathological, biophysical and locomotor activity assessments.

RESULTS AND DISCUSSION

The BALB/c mice yielded an optimal psoriasis-like phenotype with IMQ + AcOH topical treatment, and the corresponding phenotypes for the other mouse strains were C57BL/6J moderate and ApoE mild. In contrast, the ApoE/SKH-hr2 mice, as a result of the absence of a Munro abscess in the histopathology analysis, left doubt about the psoriasis-like acquisition. Locomotor activity of BALB/c mice treated with IMQ, IMQ + AcOH topically and IMQ + AcOH systemically showed decreased distance and rearing coverage and increased immobility with all treatments. Hence, the BALB/c mouse strain appears to be an optimal psoriasis-like model when utilizing IMQ + AcOH topical application.

Application of imiquimod-induced murine psoriasis model in evaluating interleukin-17A antagonist

BACKGROUND

Interleukin-17A (IL17A) is a proinflammatory cytokine critically involved in autoimmune diseases, and monoclonal antibodies of IL17A have been approved for clinical treatment of psoriasis. However, a usable psoriatic animal model has been always required for preclinical evaluation of IL17A antagonists. Imiquimod (IMQ)-induced psoriasis model is widely used in fundamental research, but it's not able to accurately show anti-psoriatic effect of IL17A antagonists with conventional modelling condition.

RESULTS

On female C57BL/6 mice, with optimization on the usage of IMQ, positive control reagent and anti-mIL17A antibody, a 7-day model with proper testing window, acceptable disease severity as well as high repeatability was developed, and the efficacy of IL17A antagonist can be objectively evaluated by several qualitative and quantitative indices. Meanwhile, we validated the detailed involvement of IL17A signaling in disease progression, confirmed that the expression levels of IL17A and its related cytokines were induced by IMQ application, and its downstream cytokines can be inhibited by IL17A antagonist treatment. In further study, we revealed that IL17A was transient induced by IMQ and directly caused downstream signaling activation. This finding on the kinetical change of IL17A signaling will manifest the pharmacokinetics-pharmacodynamics investigation of IL17A antagonists.

CONCLUSIONS

Our work presents the application of a convenient psoriatic animal model in the research and development of IL17A antagonists, meanwhile providing extra evidence for understanding IL17A's role in the progression of IMQ-induced psoriasis model, which manifest the research and development of IL17A antagonists.

Bruton's tyrosine kinase inhibition attenuates oxidative stress in systemic immune cells and renal compartment during sepsis-induced acute kidney injury in mice

Sepsis is a life-threatening condition which affects multiple organs including the kidney. Sepsis-induced acute kidney injury (AKI) is a major health burden throughout the globe. Pathogenesis of sepsis-induced AKI is complex; however, it involves both innate and adaptive immune cells such as B cells, T cells, dendritic cells (DCs), macrophages, and neutrophils. Bruton's tyrosine kinase (BTK) is reportedly involved in inflammatory and oxidative signaling in different immune cells, however its contribution with respect to sepsis-induced AKI has not been delineated. This study attempted to investigate the role of BTK and its inhibition on oxidizing enzymes NADPH oxidase (NOX-2) and inducible nitric oxide synthase (iNOS) in DCs, neutrophils, and B cells during AKI. Our data reveal that BTK is activated in DCs, neutrophils, and B cells which causes an increase in AKI associated biochemical markers such as serum creatinine/blood urea nitrogen, renal myeloperoxidase activity, and histopathological disturbances in renal tubular structures. Activation of BTK causes upregulation of NOX-2/iNOS/nitrotyrosine in these immune cells and kidney. Treatment with BTK inhibitor, Ibrutinib causes attenuation in AKI associated dysfunction in biochemical parameters (serum creatinine/blood urea nitrogen, renal myeloperoxidase activity) and oxidative stress in immune cells and kidney (iNOS/NOX2/lipid peroxides/nitrotyrosine/protein carbonyls). In summary, the current investigation reveals a compelling role of BTK signaling in sepsis-induced AKI which is evident from amelioration of AKI associated renal dysfunction after its inhibition.

Inhibition of interleukin-2-inducible T-cell kinase causes reduction in imiquimod-induced psoriasiform inflammation through reduction of Th17 cells and enhancement of Treg cells in mice

Psoriasis is a debilitating chronic skin disease with a worldwide prevalence. Its main features include well-marked silvery scales on the skin of hands and feet and back which arise due to hyperproliferation of keratinocytes and infiltration of immune cells in the skin. Multiple interactions exist between adaptive immune cells such as T cells and innate immune cells such as neutrophils and macrophages which are key players in the pathogenesis of psoriasis. Interleukin-2-inducible T-cell kinase (ITK) plays a key role in Th17 cell development through control of several transcription factors. ITK has been shown to control NFATc1, NFkB and STAT3 in CD4⁺ T cells. Effect of ITK inhibitor in imiquimod (IMQ)-induced psoriasiform inflammation remains to be explored. In the current examination, role of ITK signaling and its inhibition blockade were evaluated on NFATc1, NFkB and STAT3, IL-17A, TNF-α, IFN-γ, Foxp3, IL-10 in CD4⁺ T cells in IMQ model. Our data display that ITK signaling is involved in IMQ-induced psoriatic inflammation as paralleled by enhancement of p-ITK, NFATc1, p-NFkB and p-STAT3 in CD4⁺ T cells. It was associated with enhancement of Th17/Th1 cells and neutrophilic inflammation in the skin. Preventive treatment with ITK inhibitor led to a reduction in Th17/Th1 cells and enhancement of Treg cells. Overall, this study suggests that ITK signaling is an important modulator of transcription factor signaling in CD4⁺ T cells which is associated with Th17/Th1 cells and psoriasiform inflammation in mice. ITK signaling blockade could be a therapeutic target for the treatment of psoriatic inflammation.

Acetate attenuates perioperative neurocognitive disorders in aged mice

Perioperative neurocognitive disorders are common in elderly patients who have undergone surgical procedures. Neuroinflammation induced by microglial activation is a hallmark of these neurological disorders. Acetate can suppress inflammation in the context of inflammatory diseases. We employed an exploratory laparotomy model with isoflurane anesthesia to study the effects of acetate on perioperative neurocognitive disorders in aged mice. Neurocognitive function was assessed with open-field tests and Morris water maze tests 3 or 7 days post-surgery. Acetate ameliorated the surgery-induced cognitive deficits of aged mice and inhibited the activation of IBA-1, a marker of microglial activity. Acetate also reduced expression of inflammatory proteins (tumor necrosis factor-α, interleukin-1β and interleukin-6), oxidative stress factors (NADPH oxidase 2, inducible nitric oxide synthase and reactive oxygen species), and signaling molecules (nuclear factor kappa B and mitogen-activated protein kinase) in the hippocampus. BV2 microglial cells were used to verify the anti-inflammatory effects of acetate in vitro. Acetate suppressed inflammation in lipopolysaccharide-treated BV2 microglial cells, but not when GPR43 was silenced. These results suggest that acetate may bind to GPR43, thereby inhibiting microglial activity, suppressing neuroinflammation, and preventing memory deficits. This makes acetate is a promising therapeutic for surgery-induced neurocognitive disorders and neuroinflammation.

Activation of GPR43 suppresses TNF-α-induced inflammatory response in human fibroblast-like synoviocytes

Although rheumatoid arthritis (RA) has long posed a major threat to global health, the mechanisms driving the development and progression of RA remain incompletely understood. In the present study, we investigated the effects of G protein-coupled receptor 43 (GPR43/FFAR2) in various aspects of the pathogenesis of RA. To our knowledge, this is the first study to demonstrate that GPR43 is expressed on human fibroblast-like synoviocytes (FLS). Furthermore, we show that GPR43 is upregulated in FLS exposed to tumor necrosis factor-α (TNF-α). Importantly, our findings demonstrate that activation of GPR43 using its specific agonist significantly suppressed expression of the following key factors of RA: cytokines, such as interleukin-6 (IL-6), IL-8, high mobility group protein 1 (HMG-1); chemokines, such as monocyte chemoattractant protein 1 (MCP-1), intercellular adhesion molecule 1 (ICAM-1), and vascular cellular adhesion molecule 1 (VCAM-1); markers of oxidative stress, such as production of reactive oxygen species (ROS) and 4-hydroxynoneal (4-HNE); degradative enzymes, such as matrix metalloproteinase-3 (MMP-3) and MMP-13; and activation of the nuclear factor-κB (NF-κB) inflammatory signaling pathway. These results suggest a promising potential role for GPR43 as a specific target in the treatment and prevention of RA.

Bruton's tyrosine kinase inhibitor suppresses imiquimod-induced psoriasis-like inflammation in mice through regulation of IL-23/IL-17A in innate immune cells

Psoriasis is an unchecked chronic inflammation characterized by thick, erythematous, and scaly plaques on the skin. The role of innate immune cells in the pathogenesis of psoriasis is well documented. Bruton's tyrosine kinase (BTK) has been reported to execute important signaling functions in innate immune cells such as dendritic cells (DCs) and gamma delta T cells. However, whether inhibition of BTK would lead to modulation of innate immune function in the context of psoriatic inflammation remains largely unexplored. In the present study, we investigated the effect of selective BTK inhibitor, PCI-32765 on inflammatory signaling in CD11c + DCs and gamma delta T cells in imiquimod (IMQ)-induced mouse model of psoriasis-like inflammation. Our results show that IMQ treatment led to induction of p-BTK expression along with concomitant increase in inflammatory cytokines (IL-23, TNF-α) in CD11c + DCs in the skin. Preventive treatment with BTK inhibitor led to significant reversal in IMQ-induced inflammatory changes in CD11c + DCs of skin. Further, there was a significant decrease in dermal IL-17A levels and IL-17A + γδ + T cells after treatment with BTK inhibitor. Furthermore, short treatment of back skin with IMQ led to upregulated expression of p-BTK along with inflammatory cytokines in CD11c + DCs (IL-23, TNF-α) and IL-17A in γδ + T cells which were reversed by BTK inhibitor. Overall, our study proposes that BTK signaling serves a crucial signaling function in innate immune cells in the context of psoriatic inflammation in mice. Therefore, BTK might be a promising therapeutic target to treat psoriatic inflammation.

Roles of short-chain fatty acids in kidney diseases

OBJECTIVE

In kidney diseases, uncontrolled blood pressure, inflammation, oxidative stress, imbalanced immunity response, and metabolic dysfunction were associated with the progressive deterioration of renal function. Short-chain fatty acids (SCFAs), as a group of metabolites fermented by gut microbiota exerted regulatory effects on kidney diseases through their activation of trans-membrane G protein-coupled receptors and their inhibition of histone acetylation. In this review article, we updated recent research advances that provided an opportunity to explore our understanding in physiology and function of SCFAs in kidney disease.

DATA SOURCES

We performed a comprehensive search in both PubMed and Embase using "short-chain fatty acids" and "kidney" with no restrictions on publication date.

STUDY SELECTION

After reading through the title and abstract for early screening, the full text of relevant studies was identified and reviewed to summarize the roles of SCFAs in kidney diseases.

RESULTS

Though controversial, growing evidence suggested SCFAs appeared to have a complex but yet poorly understood communications with cellular and molecular processes that affected kidney function and responses to injury. From recent studies, SCFAs influenced multiple aspects of renal physiology including inflammation and immunity, fibrosis, blood pressure, and energy metabolism.

CONCLUSIONS

The roles of intestinal SCFAs in kidney diseases were exciting regions in recent years; however, clinical trials and animal experiments in kidney diseases were still lacked. Thus, more research would be needed to obtain better understanding of SCFAs' potential effects in kidney diseases.

Effect of the hyaluronic acid-poloxamer hydrogel on skin-wound healing: in vitro and in vivo studies

BACKGROUND

Recent research into skin injury and wound healing has focused mainly on post-trauma hemostasis, infection prevention, dermal regeneration and angiogenesis. However, less attention has been paid to air permeability and moisture loss prevention which also play important roles in injury healing.

METHODS

In the present work, we prepared a hyaluronic acid-poloxamer (HA-POL) hydrogel and tested the therapeutic effect of the hydrogel on skin-wound healing.

RESULTS

The HA-POL hydrogel transformed from sol to gel at 30°C, close to body temperature, and had stable moisturizing properties. HA-POL hydrogel promoted skin-wound healing and increased protein accumulation in the wound area. HA-POL hydrogel allowed greater air permeability than Band-aid, a typical wound covering. Results from transwell assays showed that the HA-POL hydrogel effectively isolated skin-wounds from bacterial invasion.

CONCLUSION

This work demonstrates the advantages of using HA-POL gel materials in the treatment of cutaneous wounds.

Inhibition of spleen tyrosine kinase attenuates psoriasis-like inflammation in mice through blockade of dendritic cell-Th17 inflammation axis

Psoriasis is a debilitating autoimmune disease of the skin characterized by acanthosis and hyperkeratosis resulting from excessive growth of keratinocytes in the epidermis and inflammatory infiltrates in the dermis. Innate immune cells such as dendritic cells (DCs), perform a critical role in the pathophysiology of psoriasis by presenting inflammatory/costimulatory signals for differentiation of Th17 cells. Recent studies point to the involvement of spleen tyrosine kinase (SYK) in inflammatory signaling cascade of DCs. However, it is yet to be determined whether SYK inhibition in DCs would lead to diminishment of psoriatic inflammation. Therefore, our study evaluated the effects of SYK inhibitor, R406 on imiquimod (IMQ)-induced psoriasis-like inflammation, expression of costimulatory/inflammatory molecules in DCs and their relationship with Th17/Treg cells. Our data show that R406 causes attenuation of IMQ-induced dermal inflammation as shown by reduction in ear/back skin thickness, acanthosis and myeloperoxidase activity. This was concurrent with reduction in inflammatory cytokines and co-stimulatory molecules in CD11c + DCs such as IL-6, IL-23, MHCII, and CD40. This favoured the suppression of Th17 cells and upregulation of Treg cells in R406-treated mice with psoriasis-like inflammation. Direct activation of TLR7 by IMQ in splenocytic cultures led to increased SYK expression in CD11c + DCs and release of IL-23/IL-6. IMQ-induced IL-6/IL-23 levels were significantly diminished by SYK inhibitor, R406 in splenocytic cultures. In essence, our study shows that SYK inhibition supresses psoriasis-like inflammation by modifying DC function in mice. Further, it implies that SYK inhibition could be a prospective therapeutic approach for the treatment of psoriasis-like inflammation.

Protein biomarker for psoriasis: A systematic review on their role in the pathomechanism, diagnosis, potential targets and treatment of psoriasis

Psoriasis is defined as a long-lasting multifactorial inflammatory autoimmune skin condition precisely characterized by delimited, erythematic papules with adherent shiny scales. The conditions are led by hyperproliferative responses of epidermis due to hyperactivation and immature keratinocytes production. The psoriatic skin consists of the thickened epidermal layer, in concurrence with inflammatory exudates in the dermis mainly of dendritic cells, neutrophils, T cells, and macrophages, contributing to the distinct manifestation of psoriatic lesions. It consents to multifaceted and discrete pathology due to the genetic and immunological alteration resulting from abnormal expression of various regulatory and structural proteins. These proteins are associated with various cellular and sub-cellular activities. Therefore, the presence of protein in a pathological cellular environment in the psoriatic lesions as well as in serum could be a great avenue for the insight of pathomechanism, anticipation and diagnosis of psoriasis. Research of protein biomarker in psoriasis is yet a developing realm to be explored by both fundamental and clinical researchers. This review is an attempt to assimilate the current discoveries and revelations of different proteins as a biomarker and their importance in pathogenesis, diagnosis, treatment, and anticipation of both the inflammatory and other dermatological aspects of psoriasis.

The Role of Metabolite-Sensing G Protein-Coupled Receptors in Inflammation and Metabolic Disease

SIGNIFICANCE

Great attention has been placed on the link between metabolism and immune function giving rise to the term "immunometabolism." It is widely accepted that inflammation and oxidative stress are key processes that underlie metabolic complications during obesity, diabetes, and atherosclerosis. Therefore, identifying the mechanisms and mediators that are involved in the regulation of both inflammation and metabolic homeostasis is of high scientific and therapeutic interest. Recent Advances: G protein-coupled receptors (GPCRs) that signal in response to metabolites have emerged as attractive therapeutic targets in inflammatory disease. Critical Issues and Future Directions: In this review, we discuss recent findings about the physiological role of the main metabolite-sensing GPCRs, their implication in immunometabolic disorders, their principal endogenous and synthetic ligands, and their potential as drug targets in inflammation and metabolic disease. Antioxid. Redox Signal. 29, 237-256.

NADPH Oxidases and Their Roles in Skin Homeostasis and Carcinogenesis

SIGNIFICANCE

Skin protects the body from dehydration, pathogens, and external mutagens. NADPH oxidases are central components for regulating the cellular redox balance. There is increasing evidence indicating that reactive oxygen species (ROS) generated by members of this enzyme family play important roles in the physiology and pathophysiology of the skin. Recent Advances: NADPH oxidases are active producers of ROS such as superoxide and hydrogen peroxide. Different isoforms are found in virtually all tissues. They play pivotal roles in normal cell homeostasis and in the cellular responses to various stressors. In particular, these enzymes are integral parts of redox-sensitive prosurvival and proapoptotic signaling pathways, in which they act both as effectors and as modulators. However, continuous (re)activation of NADPH oxidases can disturb the redox balance of cells, in the worst-case scenario in a permanent manner. Abnormal NADPH oxidase activity has been associated with a wide spectrum of diseases, as well as with aging and carcinogenesis.

CRITICAL ISSUES

Sunlight with its beneficial and deleterious effects induces the activation of NADPH oxidases in the skin. Evidence for the important roles of this enzyme family in skin cancer and skin aging, as well as in many chronic skin diseases, is now emerging.

FUTURE DIRECTIONS

Understanding the precise roles of NADPH oxidases in normal skin homeostasis, in the cellular responses to solar radiation, and during carcinogenesis will pave the way for their validation as therapeutic targets not only for the prevention and treatment of skin cancers but also for many other skin-related disorders. Antioxid. Redox Signal. 28, 1238-1261.

Systemic inflammation in asocial BTBR T+ tf/J mice predisposes them to increased psoriatic inflammation

Autistic Spectrum disorder (ASD) is a neurobehavioral disorder characterized by defects in communication skills leading to restricted sociability. ASD has immense dysregulation in immune responses which is thought to affect neuronal system and thus behavior. ASD patients and BTBR T⁺ tf/J (BTBR) autistic mice have increased systemic inflammation due to dysfunction in innate and adaptive immune responses. Recent studies suggest that ASD patients are associated with several co-morbid autoimmune disorders including psoriasis. However underlying mechanisms for this phenomenon have not been explored. In this study, we used imiquimod (IMQ)-induced psoriatic inflammation in social C57BL/6 (C57) mice and asocial BTBR mice to investigate whether systemic inflammation in BTBR is associated with increased susceptibility to psoriatic inflammation. Our data shows that BTBR mice have increased expression of TLR7/IL-6/IL-23 in systemic DCs but not in skin as compared to C57 mice at baseline. This leads to much greater psoriatic inflammation in BTBR mice upon IMQ application than C57 mice. Consequently, BTBR mice also have higher Th17 related immune responses in the skin and systemic compartment. Overall our study suggests that systemic innate (TLR7/IL-23/IL-6 in DCs) and adaptive (Th17 related signaling) immune responses are heightened in BTBR mice at baseline which predisposes them for greater psoriatic inflammation than C57 mice upon IMQ application. This could be one of the reasons for increased psoriatic inflammation in patients with ASD. Therapies that aim to decrease immune activation may not only benefit ASD-associated neurobehavioral abnormalities but also comorbid disorders such as psoriasis.

Glucose-6-phosphate dehydrogenase inhibition attenuates acute lung injury through reduction in NADPH oxidase-derived reactive oxygen species

Acute lung injury (ALI) is a heterogeneous disease with the hallmarks of alveolar capillary membrane injury, increased pulmonary oedema and pulmonary inflammation. The most common direct aetiological factor for ALI is usually parenchymal lung infection or haemorrhage. Reactive oxygen species (ROS) generated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX2) are thought to play an important role in the pathophysiology of ALI. Glucose-6-phosphate dehydrogenase (G6PD) plays an important role both in production of ROS as well as their removal through the supply of NADPH. However, how G6PD modulation affects NOX2-mediated ROS in the airway epithelial cells (AECs) during acute lung injury has not been explored previously. Therefore, we investigated the effect of G6PD inhibitor, 6-aminonicotinamide on G6PD activity, NOX2 expression, ROS production and enzymatic anti-oxidants in AECs in a mouse model of ALI induced by lipopolysaccharide (LPS). ALI led to increased G6PD activity in the AECs with concomitant elevation of NOX2, ROS, SOD1 and nitrotyrosine. G6PD inhibitor led to reduction of LPS-induced airway inflammation, bronchoalveolar lavage fluid protein concentration as well as NOX2-derived ROS and subsequent oxidative stress. Conversely, ALI led to decreased glutathione reductase activity in AECs, which was normalized by G6PD inhibitor. These data show that activation of G6PD is associated with enhancement of oxidative inflammation in during ALI. Therefore, inhibition of G6PD might be a beneficial strategy during ALI to limit oxidative damage and ameliorate airway inflammation.