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Int J Biol Sci 2024; 20(7):2476-2490. doi:10.7150/ijbs.91389 This issue Cite

Research Paper

Muscularis macrophages controlled by NLRP3 maintain the homeostasis of excitatory neurons

Yunhuan Gao^1,2,3*, Yi Shi^4*, Ming Wei^1,2,3, Xiaorong Yang^1,2,3, Yang Hao^1,2,3, Haifeng Liu⁵, Yuan Zhang^1,2,3, Lu Zhou⁵, Gang Hu^4✉, Rongcun Yang^1,2,3✉

1. Translational Medicine Institute, Tianjin Union Medical Center of Nankai University, Tianjin, 300121, China.
2. Department of Immunology, Nankai University School of Medicine; Nankai University, Tianjin 300071, China.
3. State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.
4. School of Statistics and Data Science, LPMC and KLMDASR, Nankai University, Tianjin, China.
5. Department of Gastroenterology and Hepatology, General Hospital, Tianjin Medical University, Tianjin, China.
*Y. G. and Y. S. equally contribute to this paper.

✉ Corresponding authors: Rongcun Yang (ryangedu.cn) and Gang Hu (huggsedu.cn).

Abstract

Peristaltic movements in gut are essential to propel ingested materials through the gastrointestinal tract. Intestinal resident macrophages play an important role in this physiological function through protecting enteric neurons. However, it is incompletely clear how individuals maintain the homeostasis of gut motility. Here we found that NLRP3 is a critical factor in controlling loss of muscularis resident macrophages (MMs), and demonstrate that MMs are involved in the homeostasis of excitatory neurons such as choline acetyltransferase (ChAT)⁺ and vesicular glutamate transporter 2 (VGLUT2)⁺ but not inhibitory neuronal nitric oxide synthase (nNOS)⁺ neurons. NLRP3 knockout (KO) mice had enhanced gut motility and increased neurons, especially excitatory ChAT⁺ and VGLUT2⁺ neurons. Single cell analyses showed that there had increased resident macrophages, especially MMs in NLRP3 KO mice. The MM proportion in the resident macrophages was markedly higher than those in wild-type (WT) or caspase 1/11 KO mice. Deletion of the MMs and transplantation of the NLRP3 KO bone marrow cells showed that survival of the gut excitatory ChAT⁺ and VGLUT2⁺ neurons was dependent on the MMs. Gut microbiota metabolites β-hydroxybutyrate (BHB) could promote gut motility through protecting MMs from pyroptosis. Thus, our data suggest that MMs regulated by NLRP3 maintain the homeostasis of excitatory neurons.

Keywords: Muscularis macrophages, NLRP3, excitatory neurons, gut microbiota

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