Chaperone proteins can positively influence immunity and longevity
Italian scientist Ferruccio Ritossa first studied the heat shock response in Drosophila (fruit fly) in 1962. The synthesis of these proteins in response to heat shock increased in the flies, and that is why Ritossa named the proteins “heat shock proteins.” In humans, these molecules also play an important role in health.
What are heat shock proteins?
Heat shock proteins (HSPs) are specific proteins produced when cells are briefly exposed to temperatures above their normal growth temperature. Synthesis of HSPs is a universal phenomenon that occurs in all plant and animal species studied, including humans. HSPs are also produced by prokaryotic cells, namely bacterial and archaeal. Because HSPs can also be induced by oxidants, toxins, heavy metals, free radicals, viruses, and other stressors, they are sometimes referred to as “stress proteins.”
Functions of heat shock proteins
Most HSPs are molecular chaperones that normally promote the self-assembly of newly synthesized polypeptide chains of proteins into a native spatial structure, the assembly of their complexes and their transport across membranes, and their involvement in signal transduction. A nonlethal increase in temperature above the physiological norm suppresses protein synthesis in the cell, activates heat shock factor (HSF), and enhances transcription of heat shock genes.
Exposure to a lethal temperature triggers apoptosis or programmed cell death. HSPs, in turn, inhibit apoptosis and confer thermal stability to cells upon re-stress. In this way, chaperones prevent irreversible aggregation of unfolded proteins and support restoration of their native structure and/or degradation of denatured proteins.
Classification of heat shock proteins
Heat shock proteins are classified into five main families based on their molecular weight, structure, and function. These are HSP100, 90, 70, 60 and the small HSP (sHSP) / a crystallins. Heat shock proteins or chaperones play an important role in the following processes:
- Folding / unfolding of proteins.
- Assembly of multiprotein complexes.
- Control of cell cycle and signaling.
- Protection of cells from stress.
HSP in neurodegenerative diseases
Due to limited therapeutic options, neurodegenerative diseases are a challenge for health care. Studies report that HSPs, HSP70 and HSP27 can protect neurons from several adverse conditions. Previous studies have also reported that over expression of HSP70 can delay the progression of Parkinson’s disease and Alzheimer’s disease. Therefore, HSP70 may be a potential therapeutic target for neurodegenerative diseases.
HSP in cancer
HSP90 and other co-chaperones are responsible for the folding of 200 proteins involved in various signaling pathways, and they also play a role in refolding denatured proteins after stress. Several kinases, including certain key elements of malignant transformation, are stabilized upon interaction with HSP90. Thus, HSP90 proteins play an important role in the development, proliferation, and survival of several cancers, and potential anticancer effects are observed upon inhibition of HSP90.
HSP in reproduction
During germ cell development, HSP production is increased, and they are considered the first proteins produced at the time of embryo growth. Various aspects of reproduction are affected by the presence or absence of HSP in many species. According to the various studies, HSP are continuously expressed and play a significant role in all stages of spermatogenesis.
HSPs in transplantation
HSPs are involved in allograft rejection and autoimmunity. Several HSPs, including HSP27, HSP60, and HSP70, are expressed in kidney allografts. Studies report that increased expression of the HSP70 gene and protein is associated with heart allograft rejection.
HSP in the inner ear
A protective role of HSPs in the inner ear is suggested by two types of studies. In one type of study, HSP levels are up regulated by an initial loading. Each preload resulted in a significant (30 dB) reduction in noise-induced hearing loss A second type of study examines heat shock factor 1 (HSF1), a major transcription factor for HSPs that has been shown to be present in the inner ear. In mice lacking HSF1, there is reduced protection from noise with increased hearing loss.
Sauna bathing as part of different cultures
Sauna bathing is a form of whole-body thermotherapy that has been used for thousands of years in many parts of the world in various forms (radiant heat, sweat lodges, etc.) for hygienic, health, social, and spiritual purposes. Modern sauna use includes the traditional Finnish sauna as well as the Turkish-style hammam, Russian banya, and other cultural variations characterized by architectural style, heating source, and humidity.
Traditional Finnish saunas are the best studied to date and generally involve short exposures (5-20 minutes) at temperatures of 80 °C – 100 °C (176 – 212 °F), with dry air (relative humidity of 10% to 20%) interspersed with periods of increased humidity from throwing water to overheated rocks.
In the last decade, infrared sauna cabins have become increasingly popular. These saunas use infrared emitters with different wavelengths without water or added humidity and generally run at lower temperatures (45-60 °C) (113 -140 °F) than Finnish saunas with similar exposure times. Both traditional Finnish and infrared sauna bathing may include rituals of cool-down periods and rehydration with oral fluids before, during, and/or after sauna bathing.
Going to the sauna promotes health through HSP
There is considerable evidence that sauna bathing can have profound physiological effects. Intense short-term heat exposure increases skin temperature and body temperature and activates thermoregulatory pathways via the hypothalamus and CNS (central nervous system), leading to activation of the autonomic nervous system.
Activation of the sympathetic nervous system, hypothalamic-pituitary-adrenal hormone axis, and renin-angiotensin-aldosterone system results in well-documented cardiovascular effects with increased heart rate, skin blood flow, cardiac output, and sweating. The sweat produced evaporates from the skin surface and produces cooling that facilitates temperature homeostasis.
In essence, sauna therapy utilizes the thermoregulatory feature of homeothermy, the physiological ability of mammals and birds to maintain a relatively constant body temperature with minimal deviation from a set point. At the cellular level, acute whole-body thermotherapy (in both wet and dry forms) results in discrete metabolic changes that include the production of heat shock proteins.
Conclusion on heat shock proteins and sauna
Research shows that HSP are produced in increased amounts in the body as a result of a sauna session. These have been shown to help against a wide variety of diseases. Thus, saunas can be protective for healthy people and helpful in recovery for those who are already ill.