A diet high in salt worsens the development of pielonefrita in mice and reduces the antibacterial activity of the immune system. It turned out that a large amount of salt in the diet is associated with an imbalance of hormones kidney: reduced excretion of aldosterone and increased glucocorticoids. The latter weaken the activity of neutrophils, and they are unable to digest phagocytosed bacteria. Similar effects are shown and experiments on humans. Article published in the journal Science Translational Medicine.
For the Western type of diet characterized by the consumption of large amounts of salt, but it is important to remember that a diet high in salt is associated with risks of development of many diseases, it also stimulates the inflammatory and autoimmune processes. Salt balance in the body supports the kidneys — nephrons reabsorbing their salt from primary urine and creates a high osmotic gradient thanks to which the reverse absorption of water.
On the influence of high salt concentrations on the immune system of the kidneys there are conflicting information. On the one hand, after kidney transplantation, the high salt content causes anti-inflammatory effect. However, recent studies have demonstratedthat at high osmolarity the cells of the tubular epithelium of the kidneys attract Pro-inflammatory elements of the immune system. Scientists suggest that this is the mechanism of renal protection from bacterial infections.
The urinary system is vulnerable to infections the body. Diseases of the urinary tract that are caused by bacteria are very common and affect a quarter of the world population, especially young girls. More than 70 percent of these infections associated with the bacteria Escherichia coli: they penetrate into the bladder, and thence ascend to the kidneys and cause pyelonephritis.
Scientists from Germany and Australia under the guidance of Kateřina Jobin (Jobin Katarzyna) from the University of Bonn led to the development of pielonefrita in mice, which is a week before that were fed food with high salt content. In the diet control animals the concentration of salt was either standard, or low. A direct effect of salt on the growth of colonies of Escherichia coli were tested in cultures of bacteria.
The researchers then examined a number of factors that could mediate the influence of salt on the immune system. To do this, measure the concentration in kidneys and blood of mice of a number of hormones related to salt exchange. In addition, evaluated the antibacterial activity of different types of immune cells.
Also checked the influence of diet on visokosolska people: ten volunteers during the week consumed an additional daily six grams of salt. At the beginning and at the end of this period, participants took the blood and urine tests.
In the kidneys of mice that ate food with high salt content, there were significantly more bacteria Escherichia coli (p < 0.01), and the pyelonephritis they have performed better than the control animals.