It was back in 1997 when a Japanese researcher, Makoto-Kuro, published in the journal Nature the discovery of the Klotho gene (Kl) as an anti-aging factor in mice. The results were clear: mice with a Klotho deficiency showed a series of phenotypic characteristics at a multisystem level related to premature aging; conversely, high expression levels of the gene, and therefore of the Klotho protein, appeared to promote longevity and healthy aging [1].
What Klotho affects
Twenty-seven years have passed, and numerous scientific articles have confirmed Makoto-Kuro’s discovery and extended its implications to human health. Today we know that a Klotho deficiency can have serious consequences for us, first and foremost because it increases the risk of many diseases: kidney disease, hypertension/atherosclerosis, osteoporosis, cataracts, dementia, cancer. The list is long.
Clearly, we are dealing with a protein that protects us from many diseases.
What we know about Klotho
Despite the enormous amount of work, we still do not know how to use Klotho to prevent these diseases, age well or even rejuvenate. For a simple reason. Klotho is a protein, and as such it is very difficult to use as a drug. But perhaps it will not be necessary to wait for the arrival of a “pharmacological Klotho”, because in the meantime we have learned to measure it and we are learning how to activate its gene, increasing Klotho levels in the blood.
What alpha-Klotho is and where it is found
We know three different forms of Klotho: alpha, beta and gamma. Almost always, when you hear about Klotho, it is the alpha form (α-Klotho). Alpha-Klotho is expressed mainly in the kidney and can exist in a transmembrane form (this is the name given to proteins that cross the cell membrane, acting as a hook for other proteins) or in a soluble form. The transmembrane form acts as a hook (co-receptor) for a very important molecule called FGF23 (fibroblast growth factor-23), a growth factor produced in the bones, which inhibits the synthesis of vitamin D and promotes the excretion of phosphates and the reabsorption of calcium and sodium.
The functions of the soluble forms of alpha-Klotho
The soluble forms, on the other hand, have multiple actions, including on organs distant from the one that produces them, exerting an antioxidant, anti-inflammatory and anti-aging effect on various organs. The soluble forms have been found in numerous biological fluids, including blood, urine and cerebrospinal fluid. The multiple protective effects mediated by the soluble forms of Klotho are mainly due to the inhibition or blocking of molecules such as TGF-β (which translates into counteracting processes associated with pulmonary, renal and cardiac fibrosis), IGF-1 (maintenance of metabolic homeostasis), NF-κB (reduction of inflammaging"Chronic low-grade inflammation" or inflammaging, such as a state of low intensity but constant organic inflammation (associated with an increase in some proteins, the inflammatory cytokines) that causes damage to the body.), and Wnt/β-catenin (a protein with a tumor-suppressor role). In this way, Klotho contributes to maintaining good health by counteracting the onset of many age-related diseases, including tumors.
In humans, α-Klotho is encoded by the Kl gene and is expressed mainly in the brain (choroid plexuses) and in the kidney (distal tubules), as well as in the pancreas, bone tissue and blood cells.
Tests that measure alpha-Klotho
The development of tests that measure α-Klotho in the blood is a recent matter. We have one available, which measures the α-Klotho protein, and a second under development that measures the expression levels of its Kl gene. When a gene is well expressed, protein levels in the blood increase. These are tests used in clinical research, not yet validated on large numbers, but potentially very useful for knowing whether or not a person has optimal levels of the protein.
The epigenetic mechanisms that regulate alpha-Klotho expression
In general, α-Klotho expression is regulated by various epigenetic mechanisms, including DNA methylation. Several studies have shown that hypermethylation of the Kl gene is associated with gene silencing, and that this process is associated with aging and with various age-related diseases. In a study conducted on patients with cardiovascular disease, it was observed that hypermethylation and reduced expression of the Kl gene (measured in venous blood) are associated with atherosclerosis and inflammation [3].
In addition, increased levels of Kl methylation in peripheral blood and in kidney tissue have been associated with greater severity of chronic kidney disease [4]; similarly, an increase in Kl methylation has been observed in association with kidney damage induced by exposure to cadmium [5]. Hypermethylation and the consequent reduced expression of Kl have also been associated with the risk of cataracts with advancing age [6], as well as with a poor prognosis of ovarian cancer [7] and squamous cell carcinoma of the head and neck [8].
Genetic tests for Klotho polymorphisms
We also have genetic tests available that detect the presence of gene variants (called “polymorphisms”, abbreviated SNP) associated with aging and with various age-related diseases. Among the most studied is the “KL-VS haplotype”, which is associated with longevity if present in heterozygosity (two different variants on the two chromosomes, the maternal one and the paternal one). Several studies have shown an association between some SNPs of the Kl gene and diseases of the cardiovascular and metabolic system.
It is therefore clear that, in the case of Klotho, a person can be more or less advantaged by genetics. Knowing this can help us interpret their clinical history as a whole and intensify the interventions that we know to have a certain efficacy on Klotho.
Is it really possible to measure the Klotho protein?
Based on all this knowledge, what can be done? The media have given Klotho a lot of attention in recent months, and when faced with news like this the first thing to do is to turn to a doctor for advice, knowing that the three types of tests I have described are still at the experimental stage and accessible only in a few laboratories in Italy, just as there are few doctors who know how to interpret them.
Measuring the protein can indeed detect the presence of a Klotho deficiency, just as the test that measures methylation of the Kl gene can give a warning signal many years before protein levels in the blood decrease. The interpretation of the results, however, must always be put in the context of the person’s clinical history.
It should also be borne in mind that we do not yet have a sufficient amount of data to allow us to predict optimal Klotho levels for a person in good health. The test that measures the protein in the blood, however, becomes very useful for monitoring over time the efficacy of behavioral therapies or other interventions.
In other words, it is not the snapshot of the moment that counts but its evolution over time.
How to intervene? The role of diet, exercise, stress, sleep, social connections and harmful substances
That said, the question is: “how do we intervene?”. Let us start from one consideration: healthy longevity is based on six pillars recognized by science: nutrition, physical activity, stress management, sleep quality, social connections, and non-exposure to toxic substances (smoking, alcohol, drugs). For all these pillars we have data correlating Klotho levels with the adoption of the virtuous behavior. Some examples: an American study of more than 8,000 subjects showed a correlation between a healthy diet (defined as the “healthy eating index” HEI) and Klotho levels. Another study showed the same correlation with the adoption of the Mediterranean diet (rich in fruit, vegetables, fish and olive oil). A third study showed an association between high consumption of nuts and Klotho levels. In general, diets rich in antioxidants such as Vitamins A, C and E, manganese, selenium and zinc tend to raise Klotho levels.
Physical activity seems to be a real cure-all for Klotho. In particular, moderate exercise increases levels of the protein.
Stress management is fundamental. Stress stimulates the production of cortisol, which in turn acts negatively on many physiological systems. Klotho seems to work in the opposite way to cortisol but is in turn suppressed by stress.
Managing stress is therefore fundamental if you want to maintain optimal Klotho levels.
Speaking of sleep, we have data showing the association between sleep duration and quality and Klotho levels (the optimal duration is just under 8 hours). Hypersomnia, for example, seems to have a negative effect on Klotho. Another study showed, in sedentary middle-aged subjects, a strong correlation between Klotho levels and sexual desire.
Is it possible to increase Klotho levels with nutritional supplementation?
Speaking instead of nutritional supplementation, we have some preliminary but encouraging data on molecules such as Vitamin D, turmeric, ginseng and resveratrolActive ingredient of natural origin with recognized antioxidant capacity (stilbene polyphenol). It is found in plants such as vines and in fruits such as cocoa and blackberries., or, better, its analog: polydatin. This is because resveratrol is unable to enter cells, whereas polydatin, which is nothing other than resveratrol with a sugar attached, exploits the glucose receptor present on all human cells. A study published by Taiwanese researchers showed that resveratrol activates a molecule called ATF3, which in turn induces the production of Klotho.
Resveratrol could act in combination with another molecule that has shown pro-Klotho activity, N-acetylcysteine (NAC). A study by Korean researchers showed that administering NAC to animals treated with a drug that damages the kidneys by inducing strong oxidative stress prevents kidney damage by acting on the expression of Klotho, which, among the many activities it possesses, is also a powerful activator of antioxidant defenses.
These are preliminary studies that help us formulate working hypotheses. A combination of polydatin/resveratrol and NAC, available as a nutritional supplement, has already provided interesting results in various clinical models. It will be interesting to verify whether some of its effects are mediated by Klotho.
4 “take-home” messages
In summary:
- We are able to measure the Klotho protein and/or the activation of its gene.
- We can know whether a person is more or less genetically predisposed to Klotho deficiency.
- These tests will help us assess more precisely the predisposition to healthy aging and periodically monitor the efficacy of lifestyle interventions.
- It will be very interesting to verify whether various combinations of active ingredients of natural origin are as effective as, or more effective than, lifestyle in activating Klotho, while we wait for a “pharmacological Klotho” to arrive. A wait that will inevitably be long.
