Dual molecule targeting HDAC6 leads to intratumoral CD4+ cytotoxic lymphocytes recruitment through MHC-II upregulation on lung cancer cells.

BACKGROUND: Despite the current therapeutic treatments including surgery, chemotherapy, radiotherapy and more recently immunotherapy, the mortality rate of lung cancer stays high. Regarding lung cancer, epigenetic modifications altering cell cycle, angiogenesis and programmed cancer cell death are therapeutic targets to combine with immunotherapy to improve treatment success. In a recent study, we uncovered that a molecule called QAPHA ((E)-3-(5-((2-cyanoquinolin-4-yl)(methyl)amino)-2-methoxyphenyl)-N-hydroxyacrylamide) has a dual function as both a tubulin polymerization and HDAC inhibitors. Here, we investigate the impact of this novel dual inhibitor on the immune response to lung cancer. METHODS: To elucidate the mechanism of action of QAPHA, we conducted a chemical proteomics analysis. Using an in vivo mouse model of lung cancer (TC-1 tumor cells), we assessed the effects of QAPHA on tumor regression. Tumor infiltrating immune cells were characterized by flow cytometry. RESULTS: In this study, we first showed that QAPHA effectively inhibited histone deacetylase 6, leading to upregulation of HSP90, cytochrome C and caspases, as revealed by proteomic analysis. We confirmed that QAPHA induces immunogenic cell death (ICD) by expressing calreticulin at cell surface in vitro and demonstrated its efficacy as a vaccine in vivo. Remarkably, even at a low concentration (0.5 mg/kg), QAPHA achieved complete tumor regression in approximately 60% of mice treated intratumorally, establishing a long-lasting anticancer immune response. Additionally, QAPHA treatment promoted the infiltration of M1-polarized macrophages in treated mice, indicating the induction of a pro-inflammatory environment within the tumor. Very interestingly, our findings also revealed that QAPHA upregulated major histocompatibility complex class II (MHC-II) expression on TC-1 tumor cells both in vitro and in vivo, facilitating the recruitment of cytotoxic CD4+T cells (CD4+CTL) expressing CD4+, NKG2D+, CRTAM+, and Perforin+. Finally, we showed that tumor regression strongly correlates to MHC-II expression level on tumor cell and CD4+ CTL infiltrate. CONCLUSION: Collectively, our findings shed light on the discovery of a new multitarget inhibitor able to induce ICD and MHC-II upregulation in TC-1 tumor cell. These two processes participate in enhancing a specific CD4+ cytotoxic T cell-mediated antitumor response in vivo in our model of lung cancer. This breakthrough suggests the potential of QAPHA as a promising agent for cancer treatment.

The Gut Microbiota at the Service of Immunometabolism.

The gut microbiota is implicated in immune system functions. Regulation of the metabolic processes occurring in immune cells is crucial for the maintenance of homeostasis and immunopathogenesis. Emerging data demonstrate that the gut microbiota is an actor in immunometabolism, notably through the effect of metabolites such as short-chain fatty acids, bile acids, and tryptophan metabolites. In this Perspective, we discuss the impact of the gut microbiota on the intracellular metabolism of the different subtypes of immune cells, including intestinal epithelial cells. Besides the effects on health, we discuss the potential consequences in infection context and inflammatory bowel diseases.

Ozone-Induced Aryl Hydrocarbon Receptor Activation Controls Lung Inflammation via Interleukin-22 Modulation.

Airborne ozone exposure causes severe lung injury and inflammation. The aryl hydrocarbon Receptor (AhR) (1), activated in pollutant-induced inflammation, is critical for cytokine production, especially IL-22 and IL-17A. The role of AhR in ozone-induced lung inflammation is unknown. We report here that chronic ozone exposure activates AhR with increased tryptophan and lipoxin A4 production in mice. AhR-/- mice show increased lung inflammation, airway hyperresponsiveness, and tissue remodeling with an increased recruitment of IL-17A and IL-22-expressing cells in comparison to control mice. IL-17A- and IL-22-neutralizing antibodies attenuate lung inflammation in AhR-/- and control mice. Enhanced lung inflammation and recruitment of ILC3, ILC2, and T cells were observed after T cell-specific AhR depletion using the AhRCD4cre-deficient mice. Together, the data demonstrate that ozone exposure activates AhR, which controls lung inflammation, airway hyperresponsiveness, and tissue remodeling via the reduction of IL-22 expression.

Functional and morphological differences of the lung upon acute and chronic ozone exposure in mice.

Environmental air pollutants including ozone cause severe lung injury and aggravate respiratory diseases such as asthma and COPD. Here we compared the effect of ozone on respiratory epithelium injury, inflammation, hyperreactivity and airway remodeling in mice upon acute (1ppm, 1 h) and chronic exposure (1.5ppm, 2 h, twice weekly for 6 weeks). Acute ozone exposure caused respiratory epithelial disruption with protein leak and neutrophil recruitment in the broncho-alveolar space, leading to lung inflammation and airway hyperresponsiveness (AHR) to methacholine. All these parameters were increased upon chronic ozone exposure, including collagen deposition. The structure of the airways as assessed by automatic numerical image analysis showed significant differences: While acute ozone exposure increased bronchial and lumen circularity but decreased epithelial thickness and area, chronic ozone exposure revealed epithelial injury with reduced height, distended bronchioles, enlarged alveolar space and increased collagen deposition, indicative of peribronchiolar fibrosis and emphysema as characterized by a significant increase in the density and diameter of airspaces with decreased airspace numbers. In conclusion, morphometric numerical analysis enables an automatic and unbiased assessment of small airway remodeling. The structural changes of the small airways correlated with functional changes allowing to follow the progression from acute to chronic ozone induced respiratory pathology.

Ozone exposure induces respiratory barrier biphasic injury and inflammation controlled by IL-33.

BACKGROUND: IL-33 plays a critical role in regulation of tissue homeostasis, injury, and repair. Whether IL-33 regulates neutrophil recruitment and functions independently of airways hyperresponsiveness (AHR) in the setting of ozone-induced lung injury and inflammation is unclear. OBJECTIVE: We sought to examine the role of the IL-33/ST2 axis in lung inflammation on acute ozone exposure in mice. METHODS: ST2- and Il33-deficient, IL-33 citrine reporter, and C57BL/6 (wild-type) mice underwent a single ozone exposure (1 ppm for 1 hour) in all studies. Cell recruitment in lung tissue and the bronchoalveolar space, inflammatory parameters, epithelial barrier damage, and airway hyperresponsiveness (AHR) were determined. RESULTS: We report that a single ozone exposure causes rapid disruption of the epithelial barrier within 1 hour, followed by a second phase of respiratory barrier injury with increased neutrophil recruitment, reactive oxygen species production, AHR, and IL-33 expression in epithelial and myeloid cells in wild-type mice. In the absence of IL-33 or IL-33 receptor/ST2, epithelial cell injury with protein leak and myeloid cell recruitment and inflammation are further increased, whereas the tight junction proteins E-cadherin and zonula occludens 1 and reactive oxygen species expression in neutrophils and AHR are diminished. ST2 neutralization recapitulated the enhanced ozone-induced neutrophilic inflammation. However, myeloid cell depletion using GR-1 antibody reduced ozone-induced lung inflammation, epithelial cell injury, and protein leak, whereas administration of recombinant mouse IL-33 reduced neutrophil recruitment in Il33-deficient mice. CONCLUSION: Data demonstrate that ozone causes an immediate barrier injury that precedes myeloid cell-mediated inflammatory injury under the control of the IL-33/ST2 axis. Thus IL-33/ST2 signaling is critical for maintenance of intact epithelial barrier and inflammation.