Virus Infection Is an Instigator of Intestinal Dysbiosis Leading to Type 1 Diabetes

Virus-induced diabetes mellitus: revisiting infection etiology in light of SARS-CoV-2

Diabetes mellitus (DM) is comprised of two predominant subtypes: type 1 diabetes mellitus (T1DM), accounting for approximately 5 % of cases worldwide and resulting from autoimmune destruction of insulin-producing β-cells, and type 2 (T2DM), accounting for approximately 95 % of cases globally and characterized by the inability of pancreatic β-cells to meet the demand for insulin due to a relative β-cell deficit in the setting of peripheral insulin resistance. Both types of DM involve derangement of glucose metabolism and are metabolic diseases generally considered to be initiated by a combination of genetic and environmental factors. Viruses have been reported to play a role as infectious etiological factors in the initiation of both types of DM in predisposed individuals. Among the reported viral infections causing DM in humans, the most studied include coxsackie B virus, cytomegalovirus and hepatitis C virus. The recent COVID-19 pandemic has highlighted the diabetogenic potential of SARS-CoV-2, rekindling interest in the field of virus-induced diabetes (VID). This review discusses the reported mechanisms of viral-induced DM, addressing emerging concepts in VID, as well as highlighting areas where knowledge is lacking, and further investigation is warranted.

Viral infection and host immune response in diabetes

Diabetes, a chronic metabolic disorder disrupting blood sugar regulation, has emerged as a prominent silent pandemic. Uncontrolled diabetes predisposes an individual to develop fatal complications like cardiovascular disorders, kidney damage, and neuropathies and aggravates the severity of treatable infections. Escalating cases of Type 1 and Type 2 diabetes correlate with a global upswing in diabetes-linked mortality. As a growing global concern with limited preventive interventions, diabetes necessitates extensive research to mitigate its healthcare burden and assist ailing patients. An altered immune system exacerbated by chronic hyperinflammation heightens the susceptibility of diabetic individuals to microbial infections, including notable viruses like SARS-CoV-2, dengue, and influenza. Given such a scenario, we scrutinized the literature and compiled molecular pathways and signaling cascades related to immune compartments in diabetics that escalate the severity associated with the above-mentioned viral infections in them as compared to healthy individuals. The pathogenesis of these viral infections that trigger diabetes compromises both innate and adaptive immune functions and pre-existing diabetes also leads to heightened disease severity. Lastly, this review succinctly outlines available treatments for diabetics, which may hold promise as preventive or supportive measures to effectively combat these viral infections in the former.

The helminth-derived peptide, FhHDM-1, reverses the trained phenotype of NOD bone-marrow-derived macrophages and regulates proinflammatory responses

We implicate a phenotype of trained immunity in bone-marrow-derived macrophages in the onset and progression of type 1 diabetes in nonobese diabetic mice. Treatment with FhHDM-1 reversed immune training, reducing histone methylation and glycolysis, and decreasing proinflammatory cytokine production to the same level as macrophages from nondiabetic immune-competent BALB/c mice.

Managing type 1 diabetes in children and young people: challenges and solutions

Type 1 diabetes is the most common form of diabetes in school-age children. Effective management and self-management at home and during school hours are essential to improve the quality of life of children and young people and reduce their risk of developing complications such as cardiovascular disease and kidney disease. There are, however, multiple barriers to effective management and self-management, notably in adolescence. Interventions, education and support based on clear psychoeducational principles improve the outcomes of children and young people. This article explores type 1 diabetes including its causes and risk factors, presentation and diagnosis, complications and comorbidities, and treatment and management. It focuses in particular on the role of nurses in supporting self-management and on the challenges of type 1 diabetes care in school.

The Effects of Viruses on Insulin Sensitivity and Blood-Brain Barrier Function

In this review manuscript, we discuss the effects of select common viruses on insulin sensitivity and blood-brain barrier (BBB) function and the potential overlapping and distinct mechanisms involved in these effects. More specifically, we discuss the effects of human immunodeficiency virus (HIV), herpes, hepatitis, influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 viruses on insulin sensitivity and BBB function and the proposed underlying mechanisms. These viruses differ in their ability to be transported across the BBB, disrupt the BBB, and/or alter the function of the BBB. For RSV and SARS-CoV-2, diabetes increases the risk of infection with the virus, in addition to viral infection increasing the risk for development of diabetes. For HIV and hepatitis C and E, enhanced TNF-a levels play a role in the detrimental effects. The winter of 2022-2023 has been labeled as a tridemic as influenza, RSV, and COVID-19 are all of concern during this flu season. There is an ongoing discussion about whether combined viral exposures of influenza, RSV, and COVID-19 have additive, synergistic, or interference effects. Therefore, increased efforts are warranted to determine how combined viral exposures affect insulin sensitivity and BBB function.

Intestinal Region-Dependent Alterations of Toll-Like Receptor 4 Expression in Myenteric Neurons of Type 1 Diabetic Rats

Toll-like receptor 4 (TLR4) can activate pro-inflammatory cascades in the gastrointestinal tract. Our aim was to determine TLR4 expression in myenteric neurons of different gut regions using a type 1 diabetic model. Ten weeks after the onset of hyperglycemia, myenteric whole-mount preparations from the duodenum, ileum and colon of streptozotocin-induced diabetic, insulin-treated diabetic and control rats were prepared for TLR4/peripherin double-labelling fluorescent immunohistochemistry. Immunogold electron microscopy was applied to evaluate TLR4 expression in the myenteric perikaryon and neuropil. Tissue TLR4 levels were measured by enzyme-linked immunosorbent assay. In controls, the number and proportion of the TLR4-immunoreactive myenteric neurons showed an increasing tendency to aboral direction. These values were significantly higher in diabetics compared to controls in the duodenum and ileum, but were significantly lower in the colon. In diabetics, the distribution of TLR4-labelling gold particles between the perikaryon and neuropil of myenteric neurons varied in a different way by intestinal segment. TLR4 tissue concentration changed only in the diabetic duodenum, and it decreased in muscle/myenteric plexus-containing homogenates, while it increased in mucosa/submucosa/submucous plexus-containing samples relative to controls. Insulin had beneficial effects on TLR4 expression. These findings support that chronic hyperglycemia has segment-specific effects on TLR4 expression, contributing to gastrointestinal disorders in diabetic patients.

The role of pathogens in diabetes pathogenesis and the potential of immunoproteomics as a diagnostic and prognostic tool

Diabetes mellitus (DM) is a group of metabolic diseases marked by hyperglycemia, which increases the risk of systemic infections. DM patients are at greater risk of hospitalization and mortality from bacterial, viral, and fungal infections. Poor glycemic control can result in skin, blood, bone, urinary, gastrointestinal, and respiratory tract infections and recurrent infections. Therefore, the evidence that infections play a critical role in DM progression and the hazard ratio for a person with DM dying from any infection is higher. Early diagnosis and better glycemic control can help prevent infections and improve treatment outcomes. Perhaps, half (49.7%) of the people living with DM are undiagnosed, resulting in a higher frequency of infections induced by the hyperglycemic milieu that favors immune dysfunction. Novel diagnostic and therapeutic markers for glycemic control and infection prevention are desirable. High-throughput blood-based immunoassays that screen infections and hyperglycemia are required to guide timely interventions and efficiently monitor treatment responses. The present review aims to collect information on the most common infections associated with DM, their origin, pathogenesis, and the potential of immunoproteomics assays in the early diagnosis of the infections. While infections are common in DM, their role in glycemic control and disease pathogenesis is poorly described. Nevertheless, more research is required to identify novel diagnostic and prognostic markers to understand DM pathogenesis and management of infections. Precise monitoring of diabetic infections by immunoproteomics may provide novel insights into disease pathogenesis and healthy prognosis.

Evidence Suggesting the Role of Gut Dysbiosis in Diabetic Retinopathy

Purpose

Gut dysbiosis has been identified and tested in human trials for its role in diabetes mellitus (DM). The gut-retina axis could be a potential target for retardation of diabetic retinopathy (DR), a known complication of DM. This study reviews the evidence suggesting gut dysbiosis in DR.

Methods

The published literature in the past 5 years was reviewed using predetermined keywords and articles. The review intended to determine changes in gut microbiome in DR, the hypothesized mechanisms linking to the gut-retina axis, its predictive potential for progression of DR, and the possible therapeutic targets.

Results

The gut microbiota of people with DM differ from those without it, and the gut microbiota of people with DR differ from those without it. The difference is more significant in the former (DM versus no DM) and less significant in the latter (DM without DR versus DM with DR). Early research has suggested mechanisms of the gut-retina axis, but these are not different from known changes in the gut microbiome of people with DM. The current evidence on the predictive value of the gut microbiome in the occurrence and progression of DR is low. Therapeutic avenues targeting the gut-retina axis include lifestyle changes, pharmacologic inhibitors, probiotics, and fecal microbiota transplantation.

Conclusions

Investigating the therapeutic utility of the gut ecosystem for DM and its complications like DR is an emerging area of research. The gut-retina axis could be a target for retardation of DR but needs longitudinal regional studies adjusting for dietary habits.

The etiology and pathogenesis of type 1 diabetes - A personal, non-systematic review of possible causes, and interventions

In this review after a lifelong research career, my personal opinion on the development of type 1 diabetes (T1D) from its very start to clinical manifestation will be described. T1D is a disease of an increased intestinal permeability and a reduced pancreas volume. I am convinced that virus might be the initiator and that this virus could persist on strategically significant locations. Furthermore, intake of gluten is important both in foetal life and at later ages. Disturbances in sphingolipid metabolism may also be of crucial importance. During certain stages of T1D, T cells take over resulting in the ultimate destruction of beta cells, which manifests T1D as an autoimmune disease. Several preventive and early treatment strategies are mentioned. All together this review has more new theories than usually, and it might also be more speculative than ordinarily. But without new ideas and theories advancement is difficult, even though everything might not hold true during the continuous discovery of the etiology and pathogenesis of T1D.