In vivo microscopy of murine islets of Langerhans: increased adhesion of transferred lymphocytes to islets depends on macrophage‐derived cytokines in a model of organ‐specific insulitis

Abstract

Environmental factors contribute to the pathogenesis of type 1 diabetes (insulin-dependent diabetes mellitus). Multiple low doses of streptozotocin (MLDS) induce hyperglycaemia and insulitis in mice. Previously we demonstrated that adhesion of lymphocytes to endothelium of islets is only increased when donor animals were diabetic and recipient mice had received 5 mg/kg streptozotocin (STZ). Therefore we used streptozotocin to evaluate the immunological relevance of such an irritation of islets. Lymphocytes, separated from diabetic mice (MLDS), were fluorescently labelled and injected to recipient mice that had received 5 mg/kg STZ. With in vivo microscopy we measured lymphocyte flow and adherence in islets. Expression of vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 (ICAM-1) in the pancreas was assessed using immunohistochemistry. Very late antigen-4 (VLA-4) and leucocyte function-associated antigen-1 (LFA-1) expression on transferred lymphocytes was measured with flow cytometry. Pretreatment of recipients with antibodies to cytokines or silica reduced lymphocyte adherence to islet endothelium from 2.04% (goat immunoglobulin G; IgG) or 1.82% (rat IgG) to 0.47, 0.58, 0.39 or 0. 19% for monoclonal antibody (mAb) interferon-gamma (IFN-gamma), polyclonal antibody (pAb) tumour necrosis factor-alpha (TNF-alpha), pAb interleukin (IL)-1alpha or silica, respectively. Reduced adhesion was associated with a decreased expression of VCAM-1 and ICAM-1 in islets of treated recipients compared with mice treated with 5 mg/kg STZ alone. In conclusion, pretreatment of recipients with 5 mg/kg STZ leads to an increased expression of adhesion molecules in the islets and lymphocyte adhesion to islet endothelium in vivo, demonstrating an immune response of the islets. Prevention of increased expression of ICAM-1 or VCAM-1 and reduction of lymphocyte adhesion in islets by silica or antibody indicate an involvement of macrophages and macrophage derived cytokines in the generation of this immune response.

Reduced CD4+ T-cell-specific gene expression in human type 1 diabetes mellitus

“…Interactions of lymphocyte function-associated antigen 1 (LFA-1) with ICAM-1 during priming induce both qualitative and quantitative alterations in T effector function and induce potentially autodestructive responses [37]. In experimentally produced diabetes the expression of adhesion molecules was lower than that of healthy controls [38]. These results are in accordance with those of Spatz et al who reported that human APC-s express lower levels of ICAM-1 [14].…”

Dendritic cells and macrophages are essential for the retention of lymphocytes in (peri)-insulitis of the nonobese diabetic mouse: a phagocyte depletion study

“…28 Furthermore, lymphocyte adhesion and infiltration decreased upon silica-mediated depletion of the Mf additionally suggesting that the Mf were also involved in the recruitment of lymphocytes. 29,30 This process is not only specific for pancreas, the loss of marginal zone Mf as the result of chronic Leishmania infection severely abrogated normal trafficking of lymphocytes into the white pulp of the spleen. 31 DC and Mf possibly act by inducing the addressins VCAM-1, MAdCAM-1 and ICAM-1 on the pancreatic endothelium.…”

Eukaryotic expression of the broad‐spectrum chemokine receptor antagonist vMIP‐II and its effects on T‐cell function in vitro and in vivo

“…4a). These changes in rolling behavior were not caused by alterations in blood flow which remained constant throughout the experiment as determined by a semi‐quantitative score (data not shown (30). Injection of an intracutaneous depot of sodium chloride did not induce enhanced rolling of T cells.…”