Role of resident macrophages in the immunologic response and smooth muscle dysfunction during acute allograft rejection after intestinal transplantation

Abstract

Summary Resident muscularis macrophages initiate an inflammatory cascade during ischemia/reperfusion that is associated with dysmotility and the activation of immunologic processes. We hypothesized that these muscularis macrophages may also play a potential immunologic role for acute allograft rejection in intestinal transplantation. Orthotopic SBTx (BN‐Lew) was performed without immunosuppression. Animals were sacrificed 7 days after SBTx. The role of resident macrophages was evaluated by transplantation of macrophage‐depleted and gadolinium chloride‐treated gut. Leukocyte infiltration was investigated in muscularis whole mounts by immunohistochemistry. Mediator mRNA expression was determined by Real‐Time‐RT‐PCR. Apoptosis was evaluated by TUNEL. Smooth muscle contractility was assessed in a standard organ bath. In comparison to vehicle‐treated grafts, macrophage‐depleted grafts exhibited significantly lower mediator mRNA peak expression (IL‐6, IL‐2, IL‐10, MCP‐1, iNOS, TNFα, IFNγ, FasL), leukocyte infiltrates (ED1‐ and ED2 positive monocytes and macrophages, neutrophils, CD4+ and CD8+ lymphocytes), apoptosis rates and an improved histologic rejection grading. Vehicle‐treated grafts showed a 77% decrease in smooth muscle contractility compared to naïve controls, while macrophage‐depleted gut exhibited only a 51% decrease in contractile activity. Transplantation of macrophage‐depleted gut attenuates the functionally relevant molecular and cellular immunologic response within the graft muscularis in acute allograft rejection. Resident macrophages participate in initiating these processes.

Perioperative Infliximab Application Ameliorates Acute Rejection Associated Inflammation After Intestinal Transplantation

“…This finding was highly consistent with the observed amount of cell infiltration as illustrated in Figures 3-5. Previous studies clarified the key role of resident macrophages in the setting of intestinal transplantation and their activation as response to IRI and acute rejection (11,17,22,23,42). Postoperative graft motility, as a main cause for postoperative translocation and subsequent sepsis improved significantly with infliximab treatment in the early phase after transplantation.…”

“…Total RNA extraction was performed using the RNeasy Mini Kit (Qiagen, Hilden, Germany) according to the product protocol. DNA contamination was eliminated by using Ambion DNA-free (Ambion Ltd., Huntingdon, Cambridgeshire, UK Biosystems, Darmstadt, Germany) were chosen as mediators associated with immunologic responses, apoptosis, cell proliferation, inflammation and antiinflammation used as previously published (7,22,23). Each mediator-specific amplification was normalized to an endogenous control (18 s).…”

Impact of CCR7 on the gastrointestinal field effect

“…The functional, molecular, and cellular mechanisms determining POI are to be found within the intestinal muscularis. The changes within intestinal mucosa do not influence the cellular and molecular mechanisms of POI (35,37,39,41,42,67,80,82). Previously, we could show a recruitment of CD11bϩCD103ϩ dendritic cells into the intestinal muscularis, but not into the colonic muscularis after IM, which induced a T H 1 response by producing IL-12 at the manipulated site.…”

“…These detrimental alterations are emphasized as major factors in the development of POI (4, 8, 9, 15, 16, 35-38, 40 -42). We reported a time-and trauma-degree-dependent inflammatory cascade (35,36); infiltration of leukocytes (40 -42, 72, 83), macrophages (21,22,37,87), and immunologically competent cells (35,36,40,67,69,72,81,83); and an upregulation of proinflammatory cytokines within the intestinal muscularis (36, 38 -40, 66, 68, 71, 80 -82, 84, 88). The pharmacological or genetic inhibition of macrophages ameliorated the POI in rodents (87,89).…”

Intestinal Regeneration, Residual Function and Immunological Priming Following Rescue Therapy After Rat Small Bowel Transplantation

“…Postoperative graft dysmotility occurs in the early phase after intestinal transplantation in response to ischemia/reperfusion injury, surgical manipulation and molecular inflammatory responses triggered by activation of resident macrophages in the intestinal muscle layer (4)(5)(6). This temporary dysmotility and the associated molecular changes resolve during the first 1-2 weeks after transplantation and-at first glance-do not seem to induce permanent functional changes in intestinal grafts.…”