Figure 2.

(A) PMN recruitment through FALCs during peritonitis. In basal conditions, MCs secrete CXCL13, which attracts B1 cells in FALCs and CSF1, a specific MØ growth factor. Bacterial and fungal infections stimulate the production of CXCL1 and CXCL8, by MCs. Bacterial products, CXCL1 and CXCL8 promote the recruitment of a first wave of PMNs entering the peritoneal cavity through FALCs. PMNs cause an initial inflammatory response secreting inflammatory cytokines (IL-1ß, TNF-α). Afterwards, NETosis helps in sequestering microorganisms in FALCs. (B) NETosis clearance and mononuclear cell recruitment during peritonitis. Bacterial products, as well as IL-1ß, stimulate the production of IL-6, TNF-α, CCL2, CCL3, and CXCL8 by MCs. IL-6Ra shedding by PMNs promotes a peripheral IL-6 response (transignaling). Cytokines and chemokines released during the inflammatory process favor mononuclear recruitment and differentiation. Mononuclear phagocytes differentiate in Macrophages (MØs) and dendritic cells (DCs). Among MØs, M1 subtype is endowed with pro-inflammatory and cytotoxic properties, whereas M2 MØs have an anti-inflammatory activity. Moreover, M2 MØs play a key role in the clearance of neutrophils debris due to scavenger activity.