Enterovirus infection in human pancreatic islet cells, islet tropism in vivo and receptor involvement in cultured islet beta cells

Abstract

Aims/hypothesis. It is thought that enterovirus infections cause beta-cell damage and contribute to the development of Type 1 diabetes by replicating in the pancreatic islets. We sought evidence for this through autopsy studies and by investigating known enterovirus receptors in cultured human islets. Methods. Autopsy pancreases from 12 newborn infants who died of fulminant coxsackievirus infections and from 65 Type 1 diabetic patients were studied for presence of enteroviral ribonucleic acid by in situ hybridisation. Forty non-diabetic control pancreases were included in the study. The expression and role of receptor candidates in cultured human islets were investigated with receptor-specific antibodies using immunocytochemistry and functional assays. Results. Enterovirus-positive islet cells were found in some of both autopsy specimen collections, but not in control pancreases. No infected cells were seen in exocrine tissue. The cell surface molecules, poliovirus receptor and integrin αvβ 3 , which act as enterovirus receptors in established cell lines, were expressed in beta cells. Antibodies to poliovirus receptor, human coxsackievirus and adenovirus receptor and integrin αvβ 3 protected islets and beta cells from adverse effects of poliovirus, coxsackie B viruses, and several of the arginine-glycine-aspartic acid motifs containing enteroviruses and human parechovirus 1 respectively. No evidence was found for expression of the decay-accelerating factor which acts as a receptor for several isletcell-replicating echoviruses in established cell lines. Conclusions/interpretation. The results show a definite islet-cell tropism of enteroviruses in the human pancreas. Some enteroviruses seem to use previously identified cell surface molecules as receptors in beta cells, whereas the identity of receptors used by other enteroviruses remains unknown. [Diabetologia (2004) 47:225-239]

Analysis of pancreas tissue in a child positive for islet cell antibodies

“…CAR production in islet cells, as observed in this study, confirms a previous report on islet-specific production of this molecule in normal human pancreatic islets [C. Verbeke and G. E. Blair, unpublished results]. This finding fits well with previous observations indicating clear tropism of enterovirus for human islets in patients who died of systemic enterovirus infection or diabetic ketoacidosis; the virus has been repeatedly discovered specifically in the islets, but not in the exocrine pancreas [4,20,24]. In addition, enteroviruses infect human islets in vitro.…”

“…The similar staining pattern of CAR and VP1 protein as well as polyclonal echovirus 11-specific antibodies, together with previous findings showing that enteroviruses have strong tropism for pancreatic islets [4], supports the idea that the islets of this child were infected by a coxsackievirus. Enterovirus was predominantly seen in glucagoncontaining alpha cells, while insulin-containing cells were usually negative.…”

“…For example, enteroviruses have been linked to autoimmune diabetes in both human and animal studies [2], but our knowledge of the presence of enterovirus in the human pancreas is still very limited. Enteroviruses have been detected in pancreatic islets of patients with type 1 diabetes [4] and in some studies coxsackievirus B4 was isolated from the pancreatic tissue [5][6][7].…”

The prevalence of enteroviral capsid protein vp1 immunostaining in pancreatic islets in human type 1 diabetes

“…This is consistent with studies showing that 4-5% of normal children had enteroviral RNA in their serum [4,7,8] and 11.8% had enteroviral RNA present in faecal samples [34,35]. Since a range of enteroviruses can infect human islets in vitro [12,36,37] it is possible that the pancreas is frequently colonised during an enteroviral infection.…”

“…In addition, the presence of enteroviral RNA was revealed by in situ hybridisation in the islets of four recent-onset type 1 diabetes cases [12] and the enteroviral capsid protein vp1, was detected in the beta cells of two of five patients with type 1 diabetes, and in a sixth diabetic patient who had received a recent pancreatic transplant [13]. Electron microscopic analysis revealed the presence of virus particles within the islet beta cells of vp1-positive cases, and a strain of CVB4 was isolated from the pancreas of one patient.…”