Eosinophils in infection and intestinal immunity

Abstract

Purpose of Review Inflammatory bowel diseases (IBDs; e.g. Crohn’s disease and ulcerative colitis) are thought to be a consequence of an uncontrolled inflammatory response against luminal antigens, including commensal bacteria. The observed link between eosinophil levels and severity and remission rates in IBD has led to speculation that eosinophils may contribute to the antimicrobial inflammatory response in IBD. Recent Findings Eosinophils express the necessary cellular machinery (innate immune receptors, pro-inflammatory cytokines, antibacterial proteins and DNA traps) to mount an efficient antibacterial response; however, the rapid decline in eosinophil numbers following acute systemic bacterial infection suggests a very limited role for eosinophils in bacterial responses. Summary We describe the clinical evidence of eosinophil involvement in IBD; summarize the in vitro and in vivo evidence of eosinophil anti-bacterial activity and the biology of eosinophils focusing on eosinophil-mediated bactericidal mechanisms and the involvement of eosinophil-derived granule proteins in this response; and conceptualize the contribution of eosinophils to an anti-commensal bacterial response in IBD.

Assessment of eosinophils in gastrointestinal inflammatory disease of dogs

“…For example, eosinophil‐derived TGF‐β is linked to tissue remodeling and induction of the extracellular matrix protein periostin in patient biopsy specimens which increases eosinophil infiltration in the mucosal layer, thus facilitating disease pathogenesis 26, 27. Furthermore, as indicated above, granule proteins such as eosinophil cationic protein, Epx, and major basic protein released by activated eosinophils during inflammation can contribute to tissue damage (alter barrier function) and dysfunction (diarrhea with bleeding) 9, 10, 11, 12. Deficiency of eotaxin‐1, the eosinophil‐specific chemokine, or blockade of its receptor (CCR3) resulting in depletion of eosinophils has been shown to attenuate inflammation in experimental models of IBD,9, 28 thus supporting the overall importance of eosinophil involvement in EGID.…”

Induced pluripotent stem cells in infections

“…Eosinophils secrete many cytotoxic granule proteins that have been identified as effector molecules responsible for many of the eosinophil actions in human system. The four major eosinophil granule proteins, major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil derived neurotoxin (EDN) and eosinophil peroxidase have been shown to be involved in a number of eosinophil associated functions [13]. EDN possess antiviral activity against single stranded RNA viruses like respiratory syncytial virus, Hepatitis and HIV, whereas ECP and MBP exhibit antibacterial, antiparasitic and antiviral activities.…”

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“…Lampinen et al demonstrated that the inflammatory process in IBD involves many inflammatory cells, such as lymphocytes, macrophages, mast cells, neutrophils, and eosinophils. They indicated that eosinophils are proinflammatory agents thus producing effects such as inflammation, tissue destruction, formation of fibrosis 29,30 . Our results showed colonic wall recovery after treatment of hyperhomocyseinemic rats with crude extract of Helix aspersa compared to experimental control.…”