<b>The effect of repetitive mild hyperthermia on body temperature, the autonomic nervous system, and innate and adaptive </b><b>immunity </b>

Abstract

The effect of repetitive mild hyperthermia on body temperature, the autonomic nervous system, and innate and adaptive immunity was investigated using a new hyperthermia treatment system, nanomist sauna (NMS). Six healthy volunteers participated and the concentration of catecholamines and cortisol, and the frequency and function of leukocytes in the peripheral blood were investigated before and after successive 7 days of hyperthermia treatment (20 min/day, 40°C, 100% relative humidity). After treatment, the blood level of adrenaline and cortisol on the 7th day was decreased compared with the 1st day, indicating the suppression of the sympathetic nervous system activity. Moreover, the frequency of CD56 + NK, CD56 + NKT and B cells on the 7th day tended to be increased compared with the 1st day. The frequency of HLA-DR-positive NK and NKT cells and expression of HLA-DR on B and T cells increased. The cytotoxicity of NK cells and proliferative response of B cells were also elevated. The results indicate that repetitive mild hyperthermia treatment might suppress excessive sympathetic dominance and modify immunity. Additionally, because it can provide the same effects as conventional hyperthermia treatments with minimal burden to the body, NMS may be a novel patient-and elderly-friendly hyperthermia treatment for health promotion.Many researchers have reported that hot springs, saunas and home baths give comfortable and appropriate hyperthermic stimulation. We have also reported a series of studies where systematic mild hyperthermia treatments could activate leukocyte, enhance immunity and treat various diseases (19,28). Thus conventional hyperthermia treatments might be effective for health promotion, including reports that hot-spring treatment is effective for the improvement of locomotive syndromes (14). However, Pilch et al. reported that wet hyperthermia is more stressful than dry hyperthermia for healthy males (22). Furthermore, it is not easy for frail people (especially children, older people and patients with locomotive disorders) to regularly take conventional hyperthermic treatments. For example, the water pressure of baths and the high temperatures (80-100°C) of dry saunas are sometimes stressful and dangerous to these individuals. In addition, conventional wet sauna has the problem of high humidity. Thus aspects of conventional hyperthermia treatments, such as high temperature, water pressure and humidity might induce stress. If such stresses could be lowered, hyperthermia treatment could be useful not only for patients and older people but also for caretakers. To pursue the further study of the effect of hyperthermia itself, we used nanomist sauna (NMS), a

Fever as an important resource for infectious diseases research

“…In humans, Tomiyama et al (11) have evaluated the effect of mild hyperthermia treatment on healthy adults, reporting an enhancement of innate and adaptive immunity. Another study focused on the characterization of the response of Dendritic Cells (DCs) to Aspergillus fumigatus at two different temperatures (homeostasis at 37ºC, and fever-like temperature at 40ºC), having found no differences in DC viability or cytokine release, but a higher maturation rate for DCs and a lower phagocytic capacity at 40ºC (31).…”

“…Some studies have shown the importance of these types of considerations when evaluating hyperthermic incubation conditions compared with the homeostasis temperature of 37°C (10). Therefore this review will focus on fever as an important variable to be considered in infectious diseases research, focusing especially on studies that reported how pyrexia can affect on the one hand the host immune response (11), and on the other hand the pathogen response.…”

Turning up the heat on COVID-19: heat as a therapeutic intervention

“…Acute heat stress has been shown to increase the TNF-alpha response of monocytes ( Zellner et al, 2002 ), enhance interleukin-2 induced activity of Natural Killer (NK) cells ( Kappel et al, 1991 ), and cause a 10-fold increase in interferon-γ production by T-lymphocytes ( Downing et al, 1988 ) while regular heat-stress has been shown to reduce adrenaline and cortisol, increase the cytotoxicity of NK cells, and enhance the proliferative response of B cells ( Tomiyama et al, 2015 ). Heat-stress also stimulates the release of Heat Shock Proteins (HSPs), ( Iguchi et al, 2012 ) which play an important role in antigen presentation and cross-presentation, activation of macrophages and lymphocytes, and activation and maturation of dendritic cells ( Tsan & Gao, 2009 ) as well as serving a chaperone function and protecting immune cells and proteins from heat-induced damage ( Singh & Hasday, 2013 ).…”

Upper respiratory tract infections and the immune system response. A review.

“…The susceptibility window to infections after heavy training is a temporary phenomenon than can last from several hours to days [30], so, another important preventive measure to preserve the body in the susceptibility window, is to adopt physical measures during the recovery phases, for example hyperthermia (saunas) in the cold environments has been shown to be an effective method. Repetitive mild hyperthermia has been proven to be effective in elevating CD56(+) NKT and B and T cells after 7 days of daily exposure at 40 degrees [31,32]. After exercise, cryotherapy has shown to have some effect on immune system recovery [33], lowering peripheral in ammation.…”