RÉSUMÉ
IL-22 plays a critical role in defending against mucosal infections, but how IL-22 production is regulated is incompletely understood. Here, we show that mice lacking IL-33 or its receptor ST2 (IL-1RL1) were more resistant to Streptococcus pneumoniae lung infection than wild-type animals and that single-nucleotide polymorphisms in IL33 and IL1RL1 were associated with pneumococcal pneumonia in humans. The effect of IL-33 on S. pneumoniae infection was mediated by negative regulation of IL-22 production in innate lymphoid cells (ILCs) but independent of ILC2s as well as IL-4 and IL-13 signaling. Moreover, IL-33's influence on IL-22-dependent antibacterial defense was dependent on housing conditions of the mice and mediated by IL-33's modulatory effect on the gut microbiota. Collectively, we provide insight into the bidirectional crosstalk between the innate immune system and the microbiota. We conclude that both genetic and environmental factors influence the gut microbiota, thereby impacting the efficacy of antibacterial immune defense and susceptibility to pneumonia.
Sujet(s)
Immunité innée , Protéine-1 analogue au récepteur de l'interleukin-1 , , Interleukine-33 , Interleukines , Streptococcus pneumoniae , Animaux , Interleukine-33/immunologie , Interleukine-33/génétique , Interleukine-33/métabolisme , Interleukines/métabolisme , Interleukines/immunologie , Interleukines/génétique , Souris , Streptococcus pneumoniae/immunologie , Protéine-1 analogue au récepteur de l'interleukin-1/métabolisme , Protéine-1 analogue au récepteur de l'interleukin-1/génétique , Protéine-1 analogue au récepteur de l'interleukin-1/immunologie , Humains , Souris knockout , Microbiote/immunologie , Souris de lignée C57BL , Pneumonie à pneumocoques/immunologie , Pneumonie à pneumocoques/microbiologie , Microbiome gastro-intestinal/immunologie , Lymphocytes/immunologie , Lymphocytes/métabolisme , Polymorphisme de nucléotide simpleRÉSUMÉ
Hospital-acquired pneumonia (HAP) is associated with high mortality and costs, and frequently caused by multidrug-resistant (MDR) bacteria. Although prior antimicrobial therapy is a major risk factor for HAP, the underlying mechanism remains incompletely understood. Here, we demonstrate that antibiotic therapy in hospitalized patients is associated with decreased diversity of the gut microbiome and depletion of short-chain fatty acid (SCFA) producers. Infection experiments with mice transplanted with patient fecal material reveal that these antibiotic-induced microbiota perturbations impair pulmonary defense against MDR Klebsiella pneumoniae. This is dependent on inflammatory monocytes (IMs), whose fatty acid receptor (FFAR)2/3-controlled and phagolysosome-dependent antibacterial activity is compromized in mice transplanted with antibiotic-associated patient microbiota. Collectively, we characterize how clinically relevant antibiotics affect antimicrobial defense in the context of human microbiota, and reveal a critical impairment of IM´s antimicrobial activity. Our study provides additional arguments for the rational use of antibiotics and offers mechanistic insights for the development of novel prophylactic strategies to protect high-risk patients from HAP.
