Early infiltration of p40IL12+CCR7+CD11b+cells is critical for fibrosis development

Tarcio Teodoro Braga, Matheus Correa-Costa, Hatylas Azevedo, Reinaldo Correia Silva, Mario Costa Cruz, Maira Estanislau Soares Almeida, Meire Ioshie Hiyane, Carlos Alberto Moreira-Filho, Marinilce Fagundes Santos, Katia Regina Perez, Iolanda Midea Cuccovia, Niels Olsen Saraiva Camara
2016 Immunity, Inflammation and Disease  
Macrophages are heterogeneous and thus can be correlated with distinct tissue outcomes after injury. Conflicting data have indicated that the M2related phenotype directly triggers fibrosis. Conversely, we hypothesize here that the inflammatory milieu provided by early infiltration of pro-inflammatory macrophages dictates tissue scarring after injury. Methods and Results: We first determined that tissue-localized macrophages exhibit a pro-inflammatory phenotype (p40IL12 þ CCR7 þ CD11b þ ) during
more » ... the early phase of a chronic injury model, in contrast to a pro-resolving phenotype (Arg1 þ IL10 þ CD206 þ CD11b þ ) at a later stage. Then, we evaluated the effects of injecting macrophages differentiated in vitro in the presence of IFNg þ LPS or IL4 þ IL13 or non-differentiated macrophages (hereafter, M0) on promoting inflammation and progression of chronic injury in macrophage-depleted mice. In addition to enhancing the expression of pro-inflammatory cytokines, the injection of M (IFNg þ LPS), but not M (IL4 þ IL13) or M0, accentuated fibrosis while augmenting levels of anti-inflammatory molecules, increasing collagen deposition and impairing organ function. We observed a similar profile after injection of sorted CCR7 þ CD11b þ cells and a more pronounced effect of M (IFNg þ LPS) cells originated from Stat6 À/À mice. The injection of M (IFNg þ LPS) cells was associated with the up-regulation of inflammation-and fibrosis-related proteins (Thbs1, Mmp7, Mmp8, and Mmp13). Conclusions: Our results suggest that pro-inflammatory macrophages promote microenvironmental changes that may lead to fibrogenesis by inducing an inflammatory milieu that alters a network of extracellular-related genes, culminating in tissue fibrosis. 300
doi:10.1002/iid3.114 pmid:27621813 pmcid:PMC5004285 fatcat:vvtbpve6ijcktbrrkmpuuadacy