Ultrastructural changes in enterocytes in subjects with Hashimoto's thyroiditis

We have recently described1 mucosal ultrastructural impairments, such as height and thickness of microvilli, space between microvilli, and thickness of tight junctions, in non-coeliac type 1 diabetic patients after a preliminary report of an alteration in intestinal mucosal permeability (IP) evaluated by the lactulose/mannitol (LA/MA) test.2,3 Therefore, in the “aetiological” classification of autoimmunity based on initiating factors,4 the category of diet induced diseases could be expanded to include type 1 diabetes and, perhaps, other endocrine autoimmune diseases. Thyroiditis is the most frequently associated autoimmune endocrine disease with type 1 diabetes. Moreover, type 1 diabetes and Hashimoto thyroiditis present similar pathogenetic mechanisms of cellular damage, a cell mediated autoimmunity induced by Th1 cytokines. However, mucosal intestinal morphology and function have not yet been studied in autoimmune thyroiditis patients. Hence we investigated intestinal mucosal ultrastructural morphology and IP in a group of patients with autoimmune thyroiditis. The study was approved by the local ethics committee. Fourteen patients (12 females and 2 males; mean age 33.2 (SD 10.2) years) and 23 controls (12 females and 11 males; mean age 27.9 (SD 8.01) years) were enrolled into the study after giving written informed consent. The diagnosis of autoimmune thyroiditis was based on the following criteria: plasma autoantibody TPO positive at high titre and a typical thyroiditis ultrasound pattern. All patients were in euthyroidism (normal FT3, FT4, and TSH plasma levels without hormonal therapy). Mean duration of known disease was 5.2 (2.5) years. All patients were negative for the presence of antigliadin antibodies IgA and IgG, antiendomysium antibodies IgA, as well as antihuman transglutaminase IgA following a gluten rich Mediterranean diet. Type 1 diabetes mellitus was excluded according to the 1997 American Diabetes Association criteria, and none of the participants had a family history of diabetes mellitus. Other intestinal and endocrine diseases were excluded through clinical and, when indicated, laboratory evaluation. Food or other allergies were excluded. None of the subjects reported gastrointestinal signs or symptoms, or was a habitual smoker, abuser of alcohol, or regularly took non-steroidal anti-inflammatory drugs

The “Perfect Storm” for Type 1 Diabetes: The Complex Interplay Between Intestinal Microbiota, Gut Permeability, and Mucosal Immunity

It is often stated that type 1 diabetes results from a complex interplay between varying degrees of genetic susceptibility and environmental factors. While agreeing with this principal, our desire is that this Perspectives article will highlight another complex interplay potentially associated with this disease involving facets related to the gut, one where individual factors that, upon their interaction with each another, form a “perfect storm” critical to the development of type 1 diabetes. This trio of factors includes an aberrant intestinal microbiota, a “leaky” intestinal mucosal barrier, and altered intestinal immune responsiveness. Studies examining the microecology of the gastrointestinal tract have identified specific microorganisms whose presence appears related (either quantitatively or qualitatively) to disease; in type 1 diabetes, a role for microflora in the pathogenesis of disease has recently been suggested. Increased intestinal permeability has also been observed in animal models of type 1 diabetes as well as in humans with or at increased-risk for the disease. Finally, an altered mucosal immune system has been associated with the disease and is likely a major contributor to the failure to form tolerance, resulting in the autoimmunity that underlies type 1 diabetes. Herein, we discuss the complex interplay between these factors and raise testable hypotheses that form a fertile area for future investigations as to the role of the gut in the pathogenesis and prevention of type 1 diabetes

Impact of Dietary Gluten on Regulatory T Cells and Th17 Cells in BALB/c Mice

Dietary gluten influences the development of type 1 diabetes (T1D) and a gluten-free (GF) diet has a protective effect on the development of T1D. Gluten may influence T1D due to its direct effect on intestinal immunity; however, these mechanisms have not been adequately studied. We studied the effect of a GF diet compared to a gluten-containing standard (STD) diet on selected T cell subsets, associated with regulatory functions as well as proinflammatory Th17 cells, in BALB/c mice. Furthermore, we assessed diet-induced changes in the expression of various T cell markers, and determined if changes were confined to intestinal or non-intestinal lymphoid compartments. The gluten-containing STD diet led to a significantly decreased proportion of γδ T cells in all lymphoid compartments studied, although an increase was detected in some γδ T cell subsets (CD8+, CD103+). Further, it decreased the proportion of CD4+CD62L+ T cells in Peyer's patches. Interestingly, no diet-induced changes were found among CD4+Foxp3+ T cells or CD3+CD49b+cells (NKT cells) and CD3−CD49b+ (NK) cells. Mice fed the STD diet showed increased proportions of CD4+CD45RBhigh+ and CD103+ T cells and a lower proportion of CD4+CD45RBlow+ T cells in both mucosal and non-mucosal compartments. The Th17 cell population, associated with the development of autoimmunity, was substantially increased in pancreatic lymph nodes of mice fed the STD diet. Collectively, our data indicate that dietary gluten influences multiple regulatory T cell subsets as well as Th17 cells in mucosal lymphoid tissue while fewer differences were observed in non-mucosal lymphoid compartments

Gut Microbiota, Probiotics and Diabetes

Diabetes is a condition of multifactorial origin, involving several molecular mechanisms related to the intestinal microbiota for its development. In type 2 diabetes, receptor activation and recognition by microorganisms from the intestinal lumen may trigger inflammatory responses, inducing the phosphorylation of serine residues in insulin receptor substrate-1, reducing insulin sensitivity. In type 1 diabetes, the lowered expression of adhesion proteins within the intestinal epithelium favours a greater immune response that may result in destruction of pancreatic β cells by CD8+ T-lymphocytes, and increased expression of interleukin-17, related to autoimmunity. Research in animal models and humans has hypothesized whether the administration of probiotics may improve the prognosis of diabetes through modulation of gut microbiota. We have shown in this review that a large body of evidence suggests probiotics reduce the inflammatory response and oxidative stress, as well as increase the expression of adhesion proteins within the intestinal epithelium, reducing intestinal permeability. Such effects increase insulin sensitivity and reduce autoimmune response. However, further investigations are required to clarify whether the administration of probiotics can be efficiently used for the prevention and management of diabetes