The intestinal environment is considered to play an important role both in colorectal tumor development and in the evolution and modulation of mucosal immunity. Studies in animals reared in germ-free (GF, without any intestinal microflora) versus conventional (CV, with regular microflora in bowel) conditions can aid in clarifying the influence of bacteria on carcinogenesis and anti-cancer immune responses in situ. The lower incidence of colon cancers and better immunological parameters in GF animals versus CV ones after chemically-induced carcinogenesis raises questions about specific characteristics of the immunological networks in each respective condition. Different levels of tolerance/regulatory mechanisms in the GF versus CV animals may influence the development of immune responses not only at the level of mucosal, but also at the systemic, immunity. We hypothesize that GF animals can better recognize and respond to evolving neoplasias in the bowel as a consequence of their less-tolerogenic immunity (i.e., due to their more limited exposure to antigens to become tolerated against at the intestinal level). In this paper, we review the role of bacteria in modulating gut environment and mucosal immunity, their importance in cancer development, and aspects of immune regulation (both at local and systemic level) that can be modified by bacterial microflora. Lastly, the use of GF animals in comparison with conventionally-raised animals is proposed as a suitable and potent model for understanding the inflammatory network and its effect on cancer immunity especially during colorectal cancer development.

Laboratory of Natural Cell Immunity Institute of Microbiology of the Academy of Sciences of the Czech Republic Prague Czech Republic

Erratum v

J Immunotoxicol. 2010 Mar;7(1):76 PubMed

Citace poskytuje Crossref.org

Local Immune Changes in Early Stages of Inflammation and Carcinogenesis Correlate with the Collagen Scaffold Changes of the Colon Mucosa

Spontaneous and Induced Tumors in Germ-Free Animals: A General Review

Gnotobiotic mouse model's contribution to understanding host-pathogen interactions

Altered gut microbiota promotes colitis-associated cancer in IL-1 receptor-associated kinase M-deficient mice

The role of gut microbiota (commensal bacteria) and the mucosal barrier in the pathogenesis of inflammatory and autoimmune diseases and cancer: contribution of germ-free and gnotobiotic animal models of human diseases