CCL3 aggravates intestinal damage in NEC by promoting macrophage chemotaxis and M1 macrophage polarization.

Abstract

NEC is a life-threatening gastrointestinal disease in neonates, the pathogenesis of which remains poorly understood. CCL3 levels in intestinal tissue of mice were measured and analyzed. HE staining was used to assess pathological changes in intestinal tissue. FCM was used to detect the proportion and phenotype of macrophages. RNA-seq and RT-PCR were used to evaluate the effect of CCL3 on macrophages. CCL3 was highly expressed in the intestinal tissues of mice with NEC and induced macrophage infiltration. Transcriptome data showed that CCL3 strongly induced a transition in the phenotype of macrophages into a proinflammatory one. Mechanistically, in vivo experiments confirmed that CCL3 induced M1 macrophage polarization in NEC intestinal tissue, thereby aggravating inflammatory injury of intestinal tissue, which was alleviated by anti-CCL3 treatment. In addition, in vitro experiments showed that CCL3 significantly enhances the expression of M1-related genes in both PMφ and BMDM while inhibiting the expression of M2-related genes, which was also alleviated by anti-CCl3 treatment. Our data elucidated the involvement of CCL3 in the pathogenesis of NEC, in which upregulated CCL3 expression exacerbated inflammatory intestinal damage by regulating macrophage chemotaxis and M1 phenotype polarization, suggesting that blocking CCL3 may be a potential strategy for effective intervention in NEC. Our study represents an important conceptual advancement that CCL3 may be one of the key culprits of intestinal tissue damage in patients with NEC. CCL3 aggravates inflammatory intestinal injury and intestinal mucosal barrier imbalance by regulating the chemotaxis, polarization, and function of macrophages. Blocking CCL3 significantly reduced NEC-mediated intestinal injury, suggesting a new potential therapeutic strategy.