PKCλ/ι regulates Th17 differentiation and house dust mite-induced allergic airway inflammation

m6A mRNA methylation-mediated MAPK signaling modulates the nasal mucosa inflammatory response in allergic rhinitis

Background

Allergic rhinitis (AR) is a complex disease in which gene-environment interactions contribute to its pathogenesis. Epigenetic modifications, such as N6-methyladenosine (m6A) modification of mRNA, play important roles in regulating gene expression in multiple physiological and pathological processes. However, the function of m6A modification in AR and the inflammatory response is poorly understood.

Methods

We used the ovalbumin (OVA) and aluminum hydroxide to induce an AR mouse model. Nasal symptoms, histopathology, and serum cytokines were examined. We performed combined m6A and RNA sequencing to analyze changes in m6A modification profiles. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and methylated RNA immunoprecipitation sequencing qPCR (MeRIP-qPCR) were used to verify differential methylation of mRNAs and the m6A methylation level. Knockdown or inhibition of Alkbh5 in nasal mucosa of mice was mediated by lentiviral infection or IOX1 treatment.

Results

We showed that m6A was enriched in a group of genes involved in MAPK signaling pathway. Moreover, we identified a MAPK pathway involving Map3k8, Erk2, and Nfκb1 that may play a role in the disrupted inflammatory response associated with nasal inflammation. The m6A eraser, Alkbh5, was highly expressed in the nasal mucosa of AR model mice. Furthermore, knockdown of Alkbh5 expression by lentiviral infection resulted in high MAPK pathway activity and a significant nasal mucosa inflammatory response. Our findings indicate that ALKBH5-mediated m6A dysregulation likely contributes to a nasal inflammatory response via the MAPK pathway.

Conclusion

Together, our data show that m6A dysregulation mediated by ALKBH5, is likely to contribute to inflammation of the nasal mucosa via the MAPK signaling pathway, suggesting that ALKBH5 is a potential biomarker for AR treatment.

Deficiency of PKCλ/ι alleviates the liver pathologic impairment of Schistosoma japonicum infection by thwarting Th2 response

BACKGROUND

The activation of immune response driven by the eggs of Schistosoma japonicum and the subsequent secretions is the culprit behind granulomatous inflammation and liver fibrosis. Evidence suggests that PKCλ/ι participates in a variety of physiological and pathological processes, including the regulation of metabolism, growth, proliferation and differentiation of cells. However, the role of PKCλ/ι in liver disease caused by Schistosoma japonicum remains unclear.

METHODS

In the present study, we observe the pathological changes of egg-induced granulomatous inflammation and fibrosis in the liver of mice infected by Schistosoma japonicum by using conditional PKCλ/ι-knockout mice and wild-type control. Immune cytokines and fibrogenic factors were analyzed by performing flow cytometry and real-time fluorescence quantitative PCR.

RESULTS

The results of H&E and Masson staining show that the degree of granulomatous lesions and fibrosis in the liver of the infected PKCλ/ι-knockout mice was significantly reduced compared with those of the infected wild-type mice. The mean area of single granuloma and hepatic fibrosis in the PKCλ/ι-knockout mice was significantly lower than that of the wild-type mice (85,295.10 ± 5399.30 μm² vs. 1,433,702.04 ± 16,294.01 μm², P < 0.001; 93,778.20 ± 8949.05 μm² vs. 163,103.01 ± 11,103.20 μm², P < 0.001), respectively. Serological analysis showed that the ALT content was significantly reduced in the infected knockout mice compared with infected wild-type mice. RT-PCR analysis showed that IL-4 content in knockout mice was significantly increased after Schistosoma japonicum infection, yet the increase was less than that in infected wild-type mice (P < 0.05). PKCλ/ι deficiency led to reduced expression of fibrosis-related factors, including TGF-β1, Col-1, Col-3, α-SMA and liver DAMP factor HMGB1. Flow cytometry analysis showed that the increasing percentage of Th2 cells, which mainly secrete IL-4 cytokines in spleen cells, was significantly lower in PKCλ/ι-deficient mice compared with wild-type mice after infection (P < 0.05).

CONCLUSIONS

Our data demonstrate that PKCλ/ι deficiency alleviating granulomatous inflammation and fibrosis in the liver of mice with S. japonicum infection by downregulating Th2 immune response is the potential molecular mechanism behind the role of PKCλ/ι in schistosomiasis.

Bergenin, a PPARγ agonist, inhibits Th17 differentiation and subsequent neutrophilic asthma by preventing GLS1-dependent glutaminolysis

Bergenin is a natural PPARγ agonist that can prevent neutrophil aggregation, and often be used in clinics for treating respiratory diseases. Recent data show that Th17 cells are important for neutrophil aggregation and asthma through secreting IL-17A. In this study, we investigated the effects of bergenin on Th17 differentiation in vitro and subsequent neutrophilic asthma in mice. Naïve T cells isolated from mouse mesenteric lymph nodes were treated with IL-23, TGF-β, and IL-6 to induce Th17 differentiation. We showed that in naïve T cells under Th17-polarizing condition, the addition of bergenin (3, 10, 30 μM) concentration-dependently decreased the percentage of CD4⁺ IL-17A⁺ T cells and mRNA expression of specific transcription factor RORγt, and function-related factors IL-17A/F, IL-21, and IL-22, but did not affect the cell vitality and apoptosis. Furthermore, bergenin treatment prevented GLS1-dependent glutaminolysis in the progress of Th17 differentiation, slightly affected the levels of SLC1A5, SLC38A1, GLUD1, GOT1, and GPT2. Glutamine deprivation, the addition of glutamate (1 mM), α-ketoglutarate (1 mM), or GLS1 plasmid all significantly attenuated the above-mentioned actions of bergenin. Besides, we demonstrated that bergenin (3, 10, and 30 μM) concentration-dependently activated PPARγ in naïve T cells, whereas PPARγ antagonist GW9662 and siPPARγ abolished bergenin-caused inhibition on glutaminolysis and Th17 differentiation. Furthermore, we revealed that bergenin inhibited glutaminolysis by regulating the level of CDK1, phosphorylation and degradation of Cdh1, and APC/C-Cdh1-mediated ubiquitin-proteasomal degradation of GLS1 after activating PPARγ. We demonstrated a correlation existing among bergenin-affected GLS1-dependent glutaminolysis, PPARγ, "CDK1-APC/C-Cdh1" signaling, and Th17 differentiation. Finally, the therapeutic effect and mechanisms for bergenin-inhibited Th17 responses and neutrophilic asthma were confirmed in a mouse model of neutrophilic asthma by administration of GW9662 or GLS1 overexpression plasmid in vivo. In conclusion, bergenin repressed Th17 differentiation and then alleviated neutrophilic asthma in mice by inhibiting GLS1-dependent glutaminolysis via regulating the "CDK1-APC/C-Cdh1" signaling after activating PPARγ.

RNA-sequencing identifies differentially expressed genes in T helper 17 cells in peritoneal fluid of patients with endometriosis

Innate and adaptive immune factors play significant roles in the pathophysiology of endometriosis. T helper 17 (Th17) cells, a pro-inflammatory T cell subset, were considered to contribute to the progression of endometriosis lesions. However, the regulatory mechanisms of Th17 cells in endometriosis remain unidentified, partially due to the difficulty in recovering live Th17 cells from endometriosis patients. In this study, by flow cytometry analysis of a set of chemokine receptors including CXCR3, CCR4, CCR10, and CCR6, live RORγt-and-IL-17A-expressing Th17 cells were enriched from peritoneal fluid (PF) of patients with different stages of endometriosis for the first time, RNA-sequencing (RNA-Seq) of these PF Th17 cells revealed significantly up-regulated genes and down-regulated genes in stage I-II and stage III-IV endometriosis, compared with their counterparts in normal PF. In conclusion, this study provides a novel method to isolate live Th17 cells from endometriosis patients, unveils an array of differentially expressed genes in endometriosis Th17 cells, and offers valuable gene expression profile information for endometriosis clinical research.

Inhibition of Rho-Kinase Downregulates Th17 Cells and Ameliorates Hepatic Fibrosis by Schistosoma japonicum Infection

BACKGROUND

Schistosomiasis is an immunopathogenic disease in which Th17 cells play vital roles. Hepatic granuloma formation and subsequent fibrosis are its main pathologic manifestations and the leading causes of hepatic cirrhosis, and effective therapeutic interventions are lacking. In this study, we explored the effects of fasudil, a selective RhoA-Rho-associated kinase (ROCK) inhibitor, on Th17 cells and the pathogenesis of schistosomiasis.

METHODS

Mice were infected with Schistosoma japonicum and treated with fasudil. The worm burden, hepatic granuloma formation, and fibrosis were evaluated. The roles of fasudil on Th17, Treg, and hepatic stellate cells were analyzed.

RESULTS

Fasudil therapy markedly reduced the granuloma size and collagen deposit in livers from mice infected with S. japonicum. However, fasudil therapy did not affect the worm burden in infected mice. The underlying cellular and molecular mechanisms were investigated. Fasudil suppressed the activation and induced the apoptosis of CD4⁺ T cells. Fasudil inhibited the differentiation and effector cytokine secretion of Th17 cells, whereas it upregulated Treg cells in vitro. It also restrained the in vivo interleukin (IL)-4 and IL-17 levels in infected mice. Fasudil directly induced the apoptosis of hepatic stellate cells and downregulated the expressions of hepatic fibrogenic genes, such as collagen type I (Col-I), Col-III, and transforming growth factor-1 (TGF-β1). These effects may contribute to its anti-pathogenic roles in schistosomiasis.

CONCLUSIONS

Fasudil inhibits hepatic granuloma formation and fibrosis with downregulation of Th17 cells. Fasudil might serve as a novel therapeutic agent for hepatic fibrosis due to schistosome infections and perhaps other disorders.

Ablation of RhoA impairs Th17 cell differentiation and alleviates house dust mite-triggered allergic airway inflammation

Asthma is a heterogeneous chronic airway inflammation in which Th2 and Th17 cells are key players in its pathogenesis. We have reported that RhoA of Rho GTPases orchestrated glycolysis for Th2 cell differentiation and allergic airway inflammation by the use of a conditional RhoA-deficient mouse line. However, the role of RhoA in Th17 cells remains to be elucidated. In this study, we investigated the effects of RhoA deficiency on Th17 cells in the context of ex vivo cell culture systems and an in vivo house dust mites (HDM)-induced allergic airway inflammation. We found that RhoA deficiency inhibited Th17 differentiation and effector cytokine secretion, which was associated with the downregulations of Stat3 and Rorγt, key Th17 transcription factors. Furthermore, loss of RhoA markedly suppressed Th17 and neutrophil-involved airway inflammation induced by HDM in mice. The infiltrating inflammatory cells in the lungs and bronchoalveolar lavage (BAL) fluids were dramatically reduced in conditional RhoA-deficient mice. Th17 as well as Th2 effector cytokines were suppressed in the airways at both protein and mRNA levels. Interestingly, Y16, a specific RhoA inhibitor, was able to recapitulate the most phenotypes of RhoA genetic deletion in Th17 differentiation and allergic airway inflammation. Our data demonstrate that RhoA is a key regulator of Th17 cell differentiation and function. RhoA might serve as a potential novel therapeutic target for asthma and other inflammatory disorders.

Rational targeting Cdc42 restrains Th2 cell differentiation and prevents allergic airway inflammation

BACKGROUND

Asthma is an allergic airway inflammation-driven disease that affects more than 300 million people world-wide. Targeted therapies for asthma are largely lacking. Although asthma symptoms can be prevented from worsening, asthma development cannot be prevented. Cdc42 GTPase has been shown to regulate actin cytoskeleton, cell proliferation and survival.

OBJECTIVES

To investigate the role and targeting of Cdc42 in Th2 cell differentiation and Th2-mediated allergic airway inflammation.

METHODS

Post-thymic Cdc42-deficient mice were generated by crossing Cdc42^flox/flox mice with dLck^icre transgenic mice in which Cre expression is driven by distal Lck promoter. Effects of post-thymic Cdc42 deletion and pharmacological targeting Cdc42 on Th2 cell differentiation were evaluated in vitro under Th2-polarized culture conditions. Effects of post-thymic Cdc42 deletion and pharmacological targeting Cdc42 on allergic airway inflammation were evaluated in ovalbumin- and/or house dust mite-induced mouse models of asthma.

RESULTS

Post-thymic deletion of Cdc42 led to reduced peripheral CD8⁺ T cells and attenuated Th2 cell differentiation, with no effect on closely related Th1, Th17 and induced regulatory T (iTreg) cells. Post-thymic Cdc42 deficiency ameliorated allergic airway inflammation. The selective inhibition of Th2 cell differentiation by post-thymic deletion of Cdc42 was recapitulated by pharmacological targeting of Cdc42 with CASIN, a Cdc42 activity-specific chemical inhibitor. CASIN also alleviated allergic airway inflammation. CASIN-treated Cdc42-deficient mice showed comparable allergic airway inflammation to vehicle-treated Cdc42-deficient mice, indicative of negligible off-target effect of CASIN. CASIN had no effect on established allergic airway inflammation.

CONCLUSION AND CLINICAL RELEVANCE

Cdc42 is required for Th2 cell differentiation and allergic airway inflammation, and rational targeting Cdc42 may serve as a preventive but not therapeutic approach for asthma control.