By the Scientific Writing of NBF-Lanes with the collaboration of Dr. Maurizio Cornelli
We examined the relationship between plasma levels of PUFA and total change in creatinine clearance during three years of follow-up, in older people enrolled in “inCHIANTI” study, an epidemiological study based on the population and conducted in Tuscany, Italy.
This study has shown that older adults with low plasma levels of total PUFA have a greater decrease in creatinine clearance. These results suggest that increased dietary intake of PUFA may be protective against the progression to chronic kidney disease.
THIS RUNDOWN ON THE NEW FRONTIERS OF CHRONIC KIDNEY DISORDERS, GIVEN THE MEDICAL EXTRACTION OF THE AUTHORS, FOCUSES ON WHAT HAPPENS IN THE HUMAN FIELD, BUT HAS INTERESTING PARALLELS WITH THE SAME TYPE OF DISTURBANCE DETECTED IN THE VETERINARY FIELD. THE AUTHORS MAKE CONTINUAL REFERENCES TO OUR SECTOR, FROM WHICH DRAWS ON ALL THE EXPERIMENTAL CASES.
EPIDEMIOLOGY OF CHRONIC KIDNEY DISEASE
This type of pathological event is proving to be a major problem affecting the public health of the older population and, in the terminal stages, can result in the need for dialysis or a transplant.
Studies (in Europe) on the prevention of terminal illnesses, out of the renal vascular compartment, show that about 12% of the adult population has some kidney shortfall; in the US, an estimated 19 million of adult individuals are at least in the early stage of a renal disease.
STRUCTURAL AND FUNCTIONAL CHANGES IN THE KIDNEY FUNCTION AGE
The changes due to aging both in structure and in kidney function have been described, not only in the human field, but in a broad range of animal species, including rats, mice, guinea pigs, dogs and cats.
Since the kidney plays a critical role in maintaining biological homeostasis, it is not surprising the fact that its operation is considered as one of the major factors for the prospects of life and often constitutes the limiting factor in selecting therapies.
TUBULE-INTERSTITIAL CHANGES WITH AGE
The kidneys (in humans) increase in size until the age of 40-50 years, and then begin to shrink over time. Most of these changes are related to tubule-interstitial changes as heart attacks, reparative phenomena (scarring) and fibrosis, rather than a loss of glomerulus.
STRUCTURAL CHANGES IN GLOMERULUS WITH AGE
With age, together with the reduction in the number of efficient glomerulus, we are seeing an increase in percentage of sclerotic glomerulus (in humans about 10% at 40 years); most affected are those cortical sub-capsular. In general, it is believed that the glomerular sclerosis represents a final stage, related to a variety of attacks to the structure, mainly ischemic and immune-mediated.
CAUSES OF CHRONIC KIDNEY DISEASES
KIDNEY DISORDERS RELATED TO AGING
It is suggested that the risk factors exert their effects in the elderly both at the level of vascular lesions for both direct damage of the kidney structures.
From the pathogenic point of view, the majority of renal alterations take off from an oxidative stress, followed by an inflammatory reaction.
In America etiopathogenetic forms are as follows:
Glomerulonephritis in 59%, hydronephrosis in 9.7%, nephropathy in 7.6%, renal disease hypertension in 6,6,%, kidney cancer in 5.2%, renal vascular disease in 4.9%, other causes in 6.4% of total cases.
MECHANISM OF KIDNEY DAMAGE FROM AGING: THE ROLE OF INFLAMMATION
Glomerulosclerosis is a syndrome due to diffuse inflammatory changes in the glomerulus, clinically characterized by the presence of hematuria with red cell cylinder, mild proteinuria and, often, high blood pressure, edema and azotemia.
The tubule-interstitial fibrosis is defined as a series of traumatic events affecting the tubules and the interstitial space, in the absence of a significant involvement of the glomerulus or renal vasculature. Medications, infections and systemic diseases are considered the main factors predisposing.
The tubule-interstitial scarring and fibrosis processes are associated with a reduction in renal function. Like the glomerulosclerosis, the tubule-interstitial fibrosis involves an inflammatory process, apoptosis and fibrosis. In the experimental field, it was possible to highlight that the proteinuria plays an important role in triggering the tubule-interstitial inflammation; the excessive resorption of albumin, by proximal tubule cells, stimulates the release of various pro-inflammatory mediators, including chemokines.
This process has been thoroughly investigated in animal models.
THE ROLE OF OMEGA-3 IN VARIOUS RENAL DISEASES
Recent studies have confirmed the existence of correlation between the polyunsaturated fatty acids (PUFAs) and the development of chronic kidney diseases. It is now shown that, in animals, dietary supplementation with PUFA reduces inflammatory processes in the kidneys and fibrosis.
IgA NEPHROPATHY
Idiopathic nephropathy IgA is the most common glomerular disease in the world. Kidney failure (in the human field) develops in 40% of patients, at 5-25 years after diagnosis. In the course of the experiment of authors, (according to randomized enrollment criteria and control groups) it was found that a suitably enriched diet of fish oil is able to slow the loss of renal function in patients with IgA nephropathy. During a period of 2 years, patients in the treatment group took 1.87 g / day of EPA and 1.36 g / day of DHA. Only 6% of them, compared to 33% of the control group (placebo), showed a 50% increase in serum creatinine. The administration of fish oil was able to reduce the evolution of the disease in people affected, as it has been able to suppress the activation and proliferation of mesangial cells in animal models (Grande et al 2000). PUFAs are able to reduce inflammation by various mechanisms, such as the nitric oxide reduction (Dasun, 2004), the regulation of TNF-α (Kielar et al, 2003), and the modulation of protein kinase (De Jonge, 1996).
CHRONIC RENAL FAILURE
The authors hypothesized that a low plasma level of PUFA could be associated with a decline in renal function in elderly patients. In order to test this hypothesis, they examined the relationship between plasma levels of total polyunsaturated fatty acids and changes in creatinine clearance, for a period of three years. These studies have confirmed the theoretical assumption of the experiment: during the period of the study, only 6% of patients treated with EPA and DHA, compared to 33% in the control group, showed an increase of 50% of creatinine.
These data suggest that supplementation of the diet most consistent, with regard to the PUFAs, is able to carry out a preventive action on the progression of chronic renal failure, and is in complete agreement with what happens in animal models, where the administration of polyunsaturated fatty acids limits the progression of kidney failure.
KIDNEY CANCERS: cancer of the renal parenchyma is equal to 80% of kidney cancers, the majority of whom are adenocarcinoma. A recent study (Wolk et al) of 36,664 women concluded that the consumption of fish rich in PUFA fatty acids may reduce the incidence of renal tumors.
DIALYSIS: Studies of patients on dialysis have concluded that supplementation with Omega 3 PUFA improves the level of triglycerides, the uremic pruritus, and oxidative stress (Lim et al, 2007)
