Islet inflammation and CXCL10 in recent-onset type 1 diabetes

Abstract

Type 1 diabetes results from a T cell-mediated destruction of insulin-producing pancreatic beta cells. Little is known on local factors contributing to migration of T cells to pancreatic tissue. We recently demonstrated evidence of viral infection in beta cells in several recent-onset type 1 diabetes patients. Islet inflammation was analysed in a series of new- or recent-onset type 1 diabetic patients and non-diabetic control subjects. Autoimmune T cell reactivity was studied in lymphocytes derived from pancreas-draining lymph nodes of one recent-onset type 1 diabetes patient in partial clinical remission. Insulitic lesions were characterized by presence of beta cells, elevated levels of the chemokine CXCL10 and infiltration of lymphocytes expressing the corresponding chemokine receptor CXCR3 in all pancreatic lesions of type 1 diabetes patients, regardless of enterovirus infection of beta cells. CXCR3 and CXCL10 were undetectable in pancreata of non-diabetic control subjects. T cells isolated from draining lymph nodes of a recent-onset patient with virally infected beta cells and in clinical remission reacted with multiple islet autoantigens and displayed a mixed interferon (IFN)-gamma/interleukin (IL)-10 cytokine pattern. Our data point to CXCL10 as an important cytokine in distressed islets that may contribute to inflammation leading to insulitis and beta cell destruction, regardless of local viral infection. We demonstrate further pro- and anti-inflammatory islet autoreactivity, indicating that different adaptive and innate immune responses may contribute to insulitis and beta cell destruction.

Fig. 1

Histology of islets of Langerhans in pancreatic tissue obtained from a recent-onset type 1 diabetes patient with virally infected β cells during clinical remission. Sections show the presence of insulin-positive cells (a) and infiltration of islets with CD3-positive leucocytes (b). Active leucocyte recruitment is visualized by expression of the inflammation-induced chemokine CXCL10 by stromal cells (c) and its corresponding receptor CXCR3 on infiltrating leucocytes (d).

Fig. 2

CXCL10 and CXCR3 expression in histology of pancreatic islets of three new-onset type 1 diabetes patients and two non-diabetic control subjects without evidence of viral infection of β cells.

Fig. 3

Immune reactivity to candidate islet autoantigens was tested in leucocytes isolated from pancreas-draining lymph nodes by T cell proliferation (left) and cytokine production (right).