Reprogramming of the Immune System by Stress and Faulty Hormonal Imprinting

PURPOSE

Hormonal imprinting is taking place perinatally at the first encounter between the developing hormone receptors and their target hormones. However, in this crucial period when the developmental window for physiological imprinting is open, other molecules, such as synthetic hormones and endocrine disruptors can bind to the receptors, leading to faulty imprinting with life-long consequences, especially to the immune system. This review presents the factors of stress and faulty hormonal imprinting that lead to reprogramming of the immune system.

METHODS

Relevant publications from Pubmed since 1990 were reviewed and synthesized.

FINDINGS

The developing immune system is rather sensitive to hormonal effects. Faulty hormonal imprinting is able to reprogram the original developmental program present in a given cell, with lifelong consequences, manifested in alteration of hormone binding by receptors, susceptibility to certain (non-infectious) diseases, and triggering of other diseases. As stress mobilizes the hypothalamic-pituitary-adrenal axis if it occurred during gestation or perinatally, it could lead to faulty hormonal imprinting in the immune system, manifested later as allergic and autoimmune diseases or weakness of normal immune defenses. Hormonal imprinting is an epigenetic process and is carried to the offspring without alteration of DNA base sequences. This means that any form of early-life stress alone or in association with hormonal imprinting could be associated with the developmental origin of health and disease (DOHaD). As puberty is also a period of reprogramming, stress or faulty imprinting can change the original (developmental) program, also with life-long consequences.

IMPLICATIONS

Considering the continuous differentiation of immune cells (from blast-cells) during the whole life, there is a possibility of late-imprinting or stress-activated reprogramming in the immune system at any periods of life, with later pathogenetic consequences.

The association between vitamin D levels and precocious puberty: a meta-analysis

The objective of this short communication was the relationship between vitamin D and precocious puberty (PP). In this study, a comprehensive search of multiple databases was performed to identify studies focused on the association between vitamin D deficiency and PP. Studies that compared serum vitamin D levels between patients with PP and controls were selected for the systematic meta-analysis. The main outcome was the mean difference in serum vitamin D levels between PP and controls. Vitamin D-deficient subjects were more likely to develop PP. Our findings suggest that PP may be linked to vitamin D deficiency. Thus, providing supplements of vitamin D to PP patients may improve their nutritional status and prevent diseases. But, the amount of vitamin D required is uncertain, so it is important to be careful when taking vitamin D supplements.

Provocation of life functions at a unicellular eukaryote level by extremely low doses of mammalian hormones: Evidences of hormesis

Hormones, characteristic to higher ranked animals, are synthesized, stored, and secreted by unicellular eukaryote animals. The unicells also have receptors for recognizing these materials and transmit the message into the cells for provoking response. The hormones are effective in very low concentrations (down to 10-21 M) and opposite effects of lower and higher concentrations can be observed. However, sometimes linear concentration effects can be found, which means that hormesis exists, nevertheless uncertain, as it is in the phase of formation (evolutionary experimentation). Hormesis, by transformation (fixation) of cytoplasmic receptor-like membrane components to receptors in the presence of the given hormone, likely helps the development of unicellular endocrine character and by this the evolution of endocrine system. The effect by extremely low concentrations of hormones had been forced by the watery way of unicellular life, which could establish the physiological concentrations of hormones in the blood of higher ranked animals. This means that hormetic low doses are the normal, effective concentrations and the high concentrations are artificial, consequently could be dangerous.

Immunity and longevity

The role of immune system is to protect the organism from the not built-in program-like alterations inside and against the agents penetrating from outside (bacteria, viruses, and protozoa). These functions were developed and formed during the evolution. Considering these functions, the immune system promotes the lengthening of lifespan and helps longevity. However, some immune functions have been conveyed by men to medical tools (e.g., pharmaceuticals, antibiotics, and prevention), especially in our modern age, which help the struggle against microbes, but evolutionarily weaken the immune system. Aging is a gradual slow attrition by autoimmunity, directed by the thymus and regulated by the central nervous system and pineal gland. Considering this, thymus could be a pacemaker of aging. The remodeling of the immune system, which can be observed in elderly people and centenarians, is probably not a cause of aging, but a consequence of it, which helps to suit immunity to the requirements. Oxidative stress also helps the attrition of the immune cells and antioxidants help to prolong lifespan. There are gender differences in the aging of the immune system as well as in the longevity. There is an advantage for women in both cases. This can be explained by hormonal differences (estrogens positively influences both processes); however, social factors are also not excluded. The endocrine disruptor chemicals act similar to estrogens, like stimulating or suppressing immunity and provoking autoimmunity; however, their role in longevity is controversial. There are some drugs (rapamycin, metformin, and selegiline) and antioxidants (as vitamins C and E) that prolong lifespan and also improve immunity. It is difficult to declare that longevity is exclusively dependent on the state of the immune system; however, there is a parallelism between the state of immune system and lifespan. It seems likely that there is not a real decline of immunity during aging, but there is a remodeling of the system according to the claims of senescence. This is manifested in the remaining (sometimes stronger) function of memory cells in contrast to the production and number of the new antigen-reactive naive T-cells.