Evaluation of cellular and humoral autoimmunity before the development of type 1 diabetes in a patient with idiopathic CD4 lymphocytopenia

Viruses as a potential environmental trigger of type 1 diabetes mellitus (Review)

The etiopathogenesis of type 1 diabetes mellitus (T1DM) is a complex multifactorial process that involves an intricate network of genetic, epigenetic, immunological, and environmental factors. Despite the advances in recent years, some aspects of the mechanisms involved in triggering the disease are still unclear. Infections with certain viruses have been suggested as possible environmental triggers for the autoimmune process that leads to selective and progressive destruction of pancreatic β-cells and insufficiency of insulin production, which is its hallmark. In this review, advances in knowledge and evidence that suggest the participation of certain viruses in the mechanisms of disease initiation and progression are described. It has been accepted that environmental factors, including viruses, can initiate and possibly sustain, accelerate, or slow down the autoimmune process and consequently damage insulin-producing pancreatic β-cells. Although the role of these agents, especially human enteroviruses, has been exhaustively studied as the most likely triggers of the activation of autoimmunity that destroys pancreatic islets and leads to T1DM, certain doubts remain. Clinical epidemiological and experimental studies in humans and animals provide consistent and increasing evidence that persistent viral infections, especially with human enteroviruses and rotavirus infections, are associated with an increased risk of the disease in individuals genetically predisposed to autoimmunity.

Allogeneic islet transplantation with monitoring of islet-specific cellular autoimmunity in a Japanese patient with type 1 diabetes: a case report

Here, we report a case of allogeneic islet transplantation in Japan. A 48-year-old man received intraportal islet transplantation (5,945 islet equivalent/kg), and stabilization of blood glucose levels and suppression of hypoglycemia were achieved. In this case, we used our original assessment method to detect the responses of the recipient's T cells to islet autoantigens over time to monitor cellular autoimmunity. Other markers could not predict graft dysfunction in advance, but our method detected the activation of islet antigen-specific CD8⁺ T cell responses before the deterioration of pancreatic beta cell function, indicating the possibility of the non-invasive detection of pancreatic beta cell damage due to recurrent autoimmunity.

Humanized mouse models reveal an immunologic classification of idiopathic CD4 lymphocytopenia subtypes

Idiopathic CD4 lymphocytopenia (ICL) is a clinically heterogeneous immunodeficiency disorder defined by low numbers of circulating CD4+ T cells and increased susceptibility to opportunistic infections. CD8+ T cells, NK, and/or B cells may also be deficient in some patients. To delineate possible pathogenic cellular mechanisms in ICL, we compared immune system development and function in NOD-RAGKO-γcKO (NRG) mice transplanted with hematopoietic stem cells from patients with ICL or healthy controls. CD34+ hematopoietic stem cells from healthy controls and patients with ICL reconstituted NRG mice equally well. In contrast, PBMC transfers into NRG mice identified 2 ICL engraftment phenotypes, reconstituting and nonreconstituting (NR), based on the absence or presence of donor lymphopenia. For patients in the NR group, the distribution of lymphocyte subsets was similar in the peripheral blood of both the patient and the corresponding humanized mice. The NR-ICL group could be further divided into individuals whose CD3+ T cells had defects in proliferation or survival. Thus, ICL cellular pathogenesis might be classified by humanized mouse models into 3 distinct subtypes: (a) T cell extrinsic, (b) T cell intrinsic affecting proliferation, and (c) T cell intrinsic affecting survival. Humanized mouse models of ICL help to delineate etiology and ultimately to guide development of individualized therapeutic strategies.