The therapeutic potential of omega-3 in type 1 diabetes
Type 1 diabetes is a polygenic, autoimmune disease in which a subclass of T cells is involved in autoimmune attacks that cause the destruction of beta pancreatic cells. The treatment for type 1 diabetes involves daily lifelong injections of recombinant insulin, as the way to reverse autoimmunity is not known. But this exogenous insulin does not contain C-peptide, which is known for its protective effects on microvessels and neurological and renal functions. Even with good glycaemic control, patients with type 1 diabetes are prone to complications such as retinopathy, neuropathy and cardiovascular disease.
In the last decade, research on possible ways of reversing autoimmunity in type 1 diabetes has focussed on islet and beta-cell stem cell allografts and various immune therapies. However, the results seem to indicate that a new paradigm is required, which considers joint intervention in various pathogenic pathways. Both genetic and environmental factors (viral infections and nutritional imbalance) could trigger the onset of type 1 diabetes. The latter factors could cause dysregulation of CD4+ T cells, which leads to CD8+ T cell infiltration in the pancreatic islets and, finally, the destruction of beta cells; if this is repeated, the result is a major reduction in the number and function of these cells. Numerous studies have shown that alterations in multiple immune cells could be involved in the cause of type 1 diabetes, hence acting on altered Th cells is essential to stopping autoimmune progression and the inflammatory attack on beta cells.
There is growing evidence that dietary supplementation with fish oil from childhood lessens autoimmune progression and type 1 diabetes: dietary consumption of omega-3 polyunsaturated fatty acids from the first year of life is associated with a lower risk of autoimmunity in islets of children with family type 1 diabetes; cod-liver oil, from the same age, has also been associated with a lower incidence of childhood onset of type 1 diabetes in high-risk children; in another sample of these characteristics, supplementation with docosahexaenoic acid (DHA) initiated in the third trimester of pregnancy or the first five months of life was associated with significantly lower levels of high-sensitivity C-reactive protein (reduction in inflammation).
Previous research by the authors of this study showed that a diet rich in omega-3 fatty acids could favour insulin secretion and provide resistance to cytokine-induced beta-cell destruction. This is the reason why the possible effects of raising circulating levels of eicosapentaenoic acid (EPA) and DHA (using genetic and nutritional interventions) in the dysregulation of T cell differentiation, the immune attack on pancreatic beta cells and their regeneration was studied in a mouse model.
The results of the study indicate the clinical potential of gene therapy or nutritional supplementation with EPA and DHA in preventing and reversing the development of autoimmunity and type 1 diabetes. Both approaches balanced the ratio of Th1 and Th2 cells, reducing Th17 cells and increasing Tregs, while also reducing circulating levels of proinflammatory cytokines. A complete recovery of pancreatic islet function and an almost complete absence of lymphocyte infiltration in the regenerated islets was observed. These findings indicate that omega-3 fatty acids have therapeutic potential in type 1 diabetes.