Immunology

Abstract

It has been known for the past 85 years that mucosal responses can be stimulated by local presentation of antigen and that the gut immune system is capable of mounting both primary and secondary responses to potentially harmful antigens while avoiding the expression of damaging responses to harmless dietary proteins. How these types of responses are induced and regulated remains unclear. In the gut attention has for some time been focused on Peyer's patches (PP) due to evidence that they play a vital role in the induction of humoral and cellular responses. Moreover, it has been established that MHC class II molecules are found in the gut mucosa on a variety of cell types outside PP, namely the lamina propria (LP). Fed antigens have also been detected in the LP and studies have shown that LP cells can stimulate allogeneic mixed lymphocyte responses and are capable of presenting soluble protein antigen to naïve T cells. This article reviews the present understanding of the possible roles of PP and LP in intestinal immunity in terms of induction, regulation, surveillance of immune responses and the antigen presenting cell types involved.

Downregulation of the Ubiquitin-Proteasome System in Normal Colonic Macrophages and Reinduction in Inflammatory Bowel Disease

“…This again sheds light on the specific function of IMACs and is in line with former reports demonstrating lower levels of MHC II molecules [22,27,28,29] and costimulatory molecules [22,30,31,32,33]. It is noteworthy that no specific part of the ubiquitinylation machinery or only the immune proteasome appears to be downregulated in IMACs.…”

Differential Gene Expression Profiles Reflecting Macrophage Polarization in Aging and Periodontitis Gingival Tissues

“…Thus, beyond the PAMPs/MAMPs engaging microbes or their products to trigger inflammatory responses, these processes are also linked to up-regulation of MHC class I and II molecules, costimulatory molecules (CD40, CD80, CD86), and adhesion molecules (Makala, Nishikawa, Suzuki and Nagasawa, 2004, Bailey, Carpentier, McMahon, Begolka and Miller, 2006, Ramachandra, Simmons and Harding, 2009) for various cell types. Both CD80 and CD86 levels were increased in healthy aged gingival tissues, and CD86 continued to increase in the periodontitis tissues.…”

Multifaceted Impacts of Periodontal Pathogens in Disorders of the Intestinal Barrier

“…The PRRs, localized either within endosomes or in the cell surface, can be expressed by intestinal epithelial cells, stromal cells, dendritic cells, macrophages and B and T cells (105). The cells of the intestinal adaptive immune system are distributed regularly throughout the mucosa in the form of organized lymphoid tissue structures of gut-associated lymphoid tissue (GALT), or lamina propria, with intraepithelial cell populations (106). Such intestinal immune tissue can principally be grouped into inductive and effector sites.…”