Exercise hormone protects kidneys from diabetes damage, study says

Released by muscle tissue during physical activity, irisin is the latest hope for scientists to protect the kidneys of people with diabetes from the damage caused by the progression of the disease. The substance, also known as exercise hormone, is considered by scientists as one of the main chemical messengers responsible for the long list of benefits provided by regular physical activity to the human body.

After a series of experiments, a group of researchers from the State University of Campinas (Unicamp) not only confirmed the benefits of the substance to the kidneys, but also described, for the first time, how it can prevent the kidney damage caused by diabetes. Silent, the disease affects between 20% and 40% of diabetics. By causing damage to the blood vessels, arteries and veins that supply the kidneys, it leads to chronic kidney failure.

“We found that aerobic exercise is associated with an increase in muscle irisin in the bloodstream and also in the kidneys, providing nephroprotection”, explains physician José Butori Lopes de Faria, from the Laboratory of Renal Pathophysiology and Diabetes Complications at the Faculty of Medical Sciences (FCM-Unicamp) and advisor to Guilherme Pedron Formigari, first author of the study.

The work, published in the journal Scientific reportswas supported by FAPESP.

Methodology

The researchers’ first step was to induce diabetes in eight-week-old mice and measure indicators of kidney damage, such as the presence of albumin in the urine. The loss of this protein is a sign that kidney cells have already begun to suffer the effects of diabetes. The animals were divided into three groups – control, sedentary diabetics and exercised diabetics (submitted to physical training on a treadmill for eight weeks).

“We saw that aerobic exercise is associated with an increase in irisin in muscle tissue and blood circulation, as well as an increase in the AMPK enzyme. [proteína quinase ativada por monofosfato de adenosina, que atua como sensor metabólico das células] in the kidneys, providing nephroprotection,” said Faria.

In the second stage, the team injected diabetic rodents with drugs and exercised to block the renal action of irisin. The substance deficiency coincided with the blocking of the beneficial effects of exercise, such as the reduction of albumin in the urine and the lower expression of substances that act on the fibrosis of the glomeruli (the kidney unit that filters the blood and eliminates waste products from the blood). metabolism). “Lack of irisin abolished the protective effects of exercise on the diabetic kidney,” the researchers wrote.

One more test was done with human renal tubular cells grown in the laboratory to find out if the treatment with irisin would be able to prevent the alterations of high glucose. During the filtering process carried out by the kidneys, the kidney tubules reabsorb and return necessary water, electrolytes and nutrients to the blood. In the test, they were immersed in a medium that simulated conditions of diabetes and contained the hormone in its recombinant form, manufactured by the industry.

“The answer was positive. We concluded that physical exercise increases irisin in the muscle and in the circulation and that, in the kidneys, the presence of this hormone activates the AMPK enzyme, which blocks the mechanisms of renal fibrosis”, explains Faria.

In a previous project, also supported by FAPESP, the nephrologist had demonstrated the role of the AMPK enzyme in renal fibrosis, which results from a state of chronic inflammation of the cells and causes them to lose their function.

In this new work, the researchers evaluated human serum (centrifuged blood, without red blood cells) from exercised and sedentary diabetics. In the samples from those who remained active, the irisin found protected the kidney and reduced the damage to tubular cells exposed to high glucose concentration. “For the first time, we can state that, in diabetes, the exercise-induced irisin/AMPK axis protects renal cells from the effects of high glucose,” the authors concluded.

Identified by biologists at Harvard University (United States) a decade ago, irisin has been the subject of many studies aimed at unraveling its mechanisms of action. Research with rodents has already shown, for example, that this hormone is also important for memory formation and the protection of neurons in rodents with a disease similar to Alzheimer’s, among other benefits.

The article Renal protection induced by physical exercise may be mediated by the irisin/AMPK axis in diabetic nephropathy can be read here.