Interleukin 33 ameliorates disturbance of regulatory T cells in pulmonary sarcoidosis

Dexamethasone alleviates pulmonary sarcoidosis by regulating the TGF-β/Smad3 signaling to promote Th17/Treg cell rebalance

Pulmonary sarcoidosis is an immune-mediated disorder closely related to Th17/Treg cell imbalance. Dexamethasone has been shown to regulate inflammation and immune responses in sarcoidosis patients. However, the underlying mechanisms of dexamethasone regulating Th17/Treg balance in sarcoidosis remain elusive. Herein, we elucidated the function role of TGF-β/Smad3 signaling in pulmonary sarcoidosis development and explored the underlying mechanism of dexamethasone in treating pulmonary sarcoidosis. We found that the TGF-β/Smad3 pathway was inactivated in pulmonary sarcoidosis patients. Propionibacterium acnes (PA) induced mouse model was generated to investigate the function of TGF-β/Smad3 signaling in vivo. Data indicated that IL17A inhibition with neutralizing antibody and activation of TGF-β/Smad3 signaling with SRI-011381 alleviated granuloma formation in the sarcoidosis mouse model. Moreover, we revealed that the Th17/Treg cell ratio was increased with PA treatment in mouse bronchoalveolar lavage fluid (BALF) and peripheral blood. The concentration of cytokines produced by Th17 cells (IL-17A, IL-23) was up-regulated in the BALF of PA-treated mice, while those produced by Tregs (IL-10, TGF-β1) presented significant reduction. The treatment of IL-17A neutralizing antibody or SRI-011381 was demonstrated to rescue the PA-induced changes in the concentration of IL-17A, IL-23, IL-10, and TGF-β1. Additionally, we demonstrated that dexamethasone treatment activated the TGF-β/Smad3 signaling in the lung tissues of pulmonary sarcoidosis mice. Dexamethasone was also revealed to promote the rebalancing of the Th17/Treg ratio and attenuated the granuloma formation in pulmonary sarcoidosis. In conclusion, dexamethasone activates the TGF-β/Smad3 signaling and induces Th17/Treg rebalance, alleviating pulmonary sarcoidosis, which suggests the potential of dexamethasone in treating pulmonary sarcoidosis.

Inhibition of phosphoinositide‑3 kinases γ/δ ameliorates pulmonary granuloma by rescuing Treg function in a sarcoidosis model

Sarcoidosis is a multisystem inflammatory disease characterized by the development of Th1/Th17/regulatory T cells (Tregs)-related non-caseating granulomas. Phosphoinositide-3 kinases δ/γ (PI3Kδ/γ) play an important role in the maintenance of effective immunity, especially for Tregs homeostasis and stability. In the present study, superoxide dismutase A (SodA) stimulation was used to establish the sarcoidosis mouse model. The second immune stimulus was accompanied by CAL-101 (PI3Kδ inhibitor) or AS-605240 (PI3Kδ/γ inhibitor) treatment. To detect the effect of the PI3Kδ/γ inhibitor on the morphology of pulmonary granuloma and the activation of the PI3K signaling pathway, hematoxylin and eosin staining and immunofluorescence and western blotting was used, respectively. Fluorescence-activated cell sorting analysis and reverse transcription-quantitative PCR were adopted to detect the effect of the PI3Kδ/γ inhibitor on the SodA-induced sarcoidosis mouse model in respect to immune cell disorder and the function of Treg cells, with CD4⁺CD25^- T cells and CD4⁺CD25⁺ T cells sorted by magnetic cell sorting. The results demonstrated that the inhibition of PI3Kδ/γ by transtracheal CAL-101/AS-605240 administration facilitated pulmonary granuloma formation. These therapeutic effects were associated with certain mechanisms, including suppressing the aberrantly activated PI3K/Akt signaling in both pulmonary granuloma and Tregs, particularly rescuing the suppressive function of Tregs. Notably, CAL-101 was more effective in immune modulation compared with AS-605240 and could overcome the aberrantly activated Akt in the lung and Tregs. These results suggest that PI3K/Akt signaling, especially the PI3Kδ subunit, can play a key role in optimal Tregs-mediated protection against pulmonary sarcoidosis. Therefore, transtracheal usage of PI3Kδ/γ inhibitors is an attractive therapy that may be developed into a new immune-therapeutic principle for sarcoidosis in the future.

Serum amyloid A/anti-CCL20 induced the rebalance of Th17/regulatory T cells in SodA-induced sarcoidosis

Sarcoidosis is a multisystemic granulomatous inflammation associated with Th17/regulatory T cell (Treg) polarization. As a marker of inflammation, serum amyloid A (SAA) could upregulate the expression of chemokine ligand 20 (CCL20), which induces the migration of Treg cells and Th17 cells by binding and activating thechemokine C-C receptor (CCR) 6. Our goal was to determine whether SAA/anti-CCL20 induces Th17/Treg rebalance in pulmonary sarcoidosis. The deposition of SAA- and Th17/Treg-related proteins in SodA-induced granulomas was tested using immunohistochemistry. Mice with SodA-induced sarcoidosis were treated with SAA or SAA + anti-CCL20, and then Th1/Th2 and Th17/Treg cells were detected by fluorescence-activated cell sorting (FACS) analysis. The expression of SAA/CCL20 and IL-23/IL-17A was detected by enzyme-linked immunosorbent assay (ELISA) and multiplex. Key proteins in the TGF-β/Smad signaling pathway were tested by western blot. SAA mainly plays a pro-inflammatory role by promoting the expression of CCL20 and IL-17A in bronchoalveolar lavage fluid (BALF) and serum, exacerbating this elevation of CD4+/CD8+ T cells in both mediastinal lymph nodes (LNs) and BALF, as well as proliferating Th1 in LNs in SodA-induced pulmonary sarcoidosis. In addition, SAA could also promote the proliferation of Tregs in LNs. Intriguingly, blocking of CCL20 could partially reverse the expression of Th17-related cytokine, ameliorate Th1/Th2 and Treg/Th17 bias in mice with SodA-induced pulmonary sarcoidosis, and rescue the overactivation of the TGF-β/Smad2/Smad3 signaling pathway. Anti-CCL20 may have the potential for therapeutic translation, targeting on the immunopathogenesis of pulmonary sarcoidosis.

Therapeutic Potential of a Combination of Electroacupuncture and Human iPSC-Derived Small Extracellular Vesicles for Ischemic Stroke

This paper aimed to explore the roles of the combination of electroacupuncture (EA) and induced pluripotent stem cell-derived small extracellular vesicles (iPSC-EVs) on mice with ischemic stroke and the underlying mechanisms. A focal cerebral ischemia model was established in C57BL/6 mice through middle cerebral artery occlusion (MCAO). After 3 days, neurological impairment and motor function were examined by performing behavioral tests. The infarct volume and neuronal apoptosis were examined using TTC staining and TUNEL assays. Flow cytometry was performed to assess the proliferation of T lymphocytes. The changes in the interleukin (IL)-33/ST2 axis were evaluated by immunofluorescence and Western blotting. The combination of EA and iPSC-EVs treatment ameliorated neurological impairments and reduced the infarct volume and neuronal apoptosis in MCAO mice. EA plus iPSC-EVs suppressed T helper (Th1) and Th17 responses and promoted the regulatory T cell (Treg) response. In addition, EA plus iPSC-EVs exerted neuroprotective effects by regulating the IL-33/ST2 axis and inhibiting the microglia and astrocyte activation. Taken together, the study shows that EA and iPSC-EVs exerted a synergistic neuroprotective effect in MCAO mice, and this treatment may represent a novel potent therapy for ischemic stroke and damage to other tissues.

Experimental models of sarcoidosis: where are we now?

PURPOSE OF REVIEW

Sarcoidosis remains a mysterious disease that presents many challenges both in pathogenetic understanding and in the management of patients. This review presents experimental models for sarcoidosis developed since 2016 and discusses their strengths and weaknesses and how they have contributed to the understanding and therapeutic approaches in this disease. In addition, future directions are proposed to overcome the limitations of current models.

RECENT FINDINGS

New cellular models using infectious antigen as trigger, and transgenic models in mice have recently been developed to study signaling pathways potentially implicated in the pathogenesis of sarcoidosis.

SUMMARY

No model fully reproduces sarcoidosis, but most of them generate data supporting key concepts and some open up therapeutic perspectives, like mTOR inhibition or IL-1β blocking. However, there are still many limitations to these models, largely related to the complexity of sarcoidosis, which might be overcome with new technologies, such as mathematical modeling.

Current perspectives on the immunopathogenesis of sarcoidosis

Sarcoidosis is an inflammatory systemic disease that commonly affects the lungs or lymph nodes but can manifest in other organs. Herein, we review the latest evidence establishing how innate and adaptive immune responses contribute to the pathogenesis and clinical course of sarcoidosis. We discuss the possible role of microbial organisms as etiologic agents in sarcoidosis and the evidence supporting sarcoidosis as an autoimmune disease. We also discuss how animal and in vitro human models have advanced our understanding of the immunopathogenesis of sarcoidosis. Finally, we discuss therapeutics for sarcoidosis and the effects on the immune system.