Polymorphonuclear leukocyte function in cancer patients treated with total body hyperthermia

A unifying model to estimate the effect of heat stress in the human innate immunity during physical activities

Public health is threatened by climate change and extreme temperature events worldwide. Differences in health predispositions, access to cooling infrastructure and occupation raises an issue of heat-related health inequality in those vulnerable and disadvantaged demographic groups. To address these issues, a comprehensive understanding of the effect of elevated body temperatures on human biological systems and overall health is urgently needed. In this paper we look at the inner workings of the human innate immunity under exposure to heat stress induced through exposure to environment and physical exertion. We couple two experimentally validated computational models: the innate immune system and thermal regulation of the human body. We first study the dynamics of critical indicators of innate immunity as a function of human core temperature. Next, we identify environmental and physical activity regimes that lead to core temperature levels that can potentially compromise the performance of the human innate immunity. Finally, to take into account the response of innate immunity to various intensities of physical activities, we utilise the dynamic core temperatures generated by a thermal regulation model. We compare the dynamics of all key players of the innate immunity for a variety of stresses like running a marathon, doing construction work, and leisure walking at speed of 4 km/h, all in the setting of a hot and humid tropical climate such as present in Singapore. We find that exposure to moderate heat stress leading to core temperatures within the mild febrile range (37, 38][Formula: see text], nudges the innate immune system into activation and improves the efficiency of its response. Overheating corresponding to core temperatures beyond 38[Formula: see text], however, has detrimental effects on the performance of the innate immune system, as it further induces inflammation, which causes a series of reactions that may lead to the non-resolution of the ongoing inflammation. Among the three physical activities considered in our simulated scenarios (marathon, construction work, and walking), marathon induces the highest level of inflammation that challenges the innate immune response with its resolution. Our study advances the current state of research towards understanding the implications of heat exposure for such an essential physiological system as the innate immunity. Although we find that among considered physical activities, a marathon of 2 h and 46 min induces the highest level of inflammation, it must be noted that construction work done on a daily basis under the hot and humid tropical climate, can produce a continuous level of inflammation triggering moieties stretched at a longer timeline beating the negative effects of running a marathon. Our study demonstrates that the performance of the innate immune system can be severely compromised by the exposure to heat stress and physical exertion. This poses significant risks to health especially to those with limited access to cooling infrastructures. This is due in part to having low income, or having to work on outdoor settings, which is the case for construction workers. These risks to public health should be addressed through individual and population-level measures via behavioural adaptation and provision of the cooling infrastructure in outdoor environments.

Old and new facts about hyperthermia-induced modulations of the immune system

Hyperthermia (HT) is a potent sensitiser for radiotherapy (RT) and chemotherapy (CT) and has been proven to modulate directly or indirectly cells of the innate and adaptive immune system. We will focus in this article on how anti-tumour immunity can be induced by HT. In contrast to some in vitro assays, in vivo examinations showed that natural killer cells and phagocytes like granulocytes are directly activated against the tumour by HT. Since heat also activates dendritic cells (DCs), HT should be combined with further death stimuli (RT, CT or immune therapy) to allocate tumour antigen, derived from, for example, necrotic tumour cells, for uptake by DCs. We will outline that induction of immunogenic tumour cells and direct tumour cell killing by HT in combination with other therapies contributes to immune activation against the tumour. Studies will be presented showing that non-beneficial effects of HT on immune cells are mostly timely restricted. A special focus is set on immune activation mediated by extracellular present heat shock proteins (HSPs) carrying tumour antigens and further danger signals released by dying tumour cells. Local HT treatment in addition to further stress stimuli exerts abscopal effects and might be considered as in situ tumour vaccination. An increased natural killer (NK) cell activity, lymphocyte infiltration and HSP-mediated induction of immunogenic tumour cells have been observed in patients. Treatments with the addition of HT therefore can be considered as a personalised cancer treatment approach by specifically activating the immune system against the individual unique tumour.

Polymorphonuclear neutrophils and cancer: intense and sustained neutrophilia as a treatment against solid tumors

Polymorphonuclear neutrophils (PMN) are the most abundant circulating immune cells and represent the first line of immune defense against infection. This review of the biomedical literature of the last 40 years shows that they also have a powerful antitumoral effect under certain circumstances. Typically, the microenvironment surrounding a solid tumor possesses many of the characteristics of chronic inflammation, a condition considered very favorable for tumor growth and spread. However, there are many circumstances that shift the chronic inflammatory state toward an acute inflammatory response around a tumor. This shift seems to convert PMN into very efficient anticancer effector cells. Clinical reports of unexpected antitumoral effects linked to the prolonged use of granulocyte colony-stimulating factor, which stimulates an intense and sustained neutrophilia, suggest that an easy way to fight solid tumors would be to encourage the development of intense peritumoral PMN infiltrates. Specifically designed clinical trials are urgently needed to evaluate the safety and efficacy of such drug-induced neutrophilia in patients with solid tumors. This antitumoral role of neutrophils may provide new avenues for the clinical treatment of cancer.

Heat, Athletes, and Immunity

During exercise, body temperature rises as a result of increased energy metabolism and heat absorbed from the environment. In response to this rise in body temperature, blood flow increases and stress hormones are released. Together, blood flow and stress hormones stimulate increases in the number of circulating leukocytes and alterations in various aspects of immune function, including cytokine production. The extent of changes in leukocyte numbers, cytokine concentrations, and immune cell function depends on how high body temperature rises and the intensity and duration of exercise. In general, increases in body temperature of ≤ 1.8° F (1° C) induce mild changes in immune function, and such changes are unlikely to increase the risk of illness in athletes, firefighters, and military personnel who regularly exercise in hot conditions. More severe immune disturbances during exercise in extreme heat (≥ 106° F or 41° C) may contribute to classical symptoms of heatstroke.

Exercising in Environmental Extremes

Athletes, military personnel, fire fighters, mountaineers and astronauts may be required to perform in environmental extremes (e.g. heat, cold, high altitude and microgravity). Exercising in hot versus thermoneutral conditions (where core temperature is > or = 1 degrees C higher in hot conditions) augments circulating stress hormones, catecholamines and cytokines with associated increases in circulating leukocytes. Studies that have clamped the rise in core temperature during exercise (by exercising in cool water) demonstrate a large contribution of the rise in core temperature in the leukocytosis and cytokinaemia of exercise. However, with the exception of lowered stimulated lymphocyte responses after exercise in the heat, and in exertional heat illness patients (core temperature > 40 degrees C), recent laboratory studies show a limited effect of exercise in the heat on neutrophil function, monocyte function, natural killer cell activity and mucosal immunity. Therefore, most of the available evidence does not support the contention that exercising in the heat poses a greater threat to immune function (vs thermoneutral conditions). From a critical standpoint, due to ethical committee restrictions, most laboratory studies have evoked modest core temperature responses (< 39 degrees C). Given that core temperature during exercise in the field often exceeds levels associated with fever and hyperthermia (approximately 39.5 degrees C) field studies may provide an opportunity to determine the effects of severe heat stress on immunity. Field studies may also provide insight into the possible involvement of immune modulation in the aetiology of exertional heat stroke (core temperature > 40.6 degrees C) and identify the effects of acclimatisation on neuroendocrine and immune responses to exercise-heat stress. Laboratory studies can provide useful information by, for example, applying the thermal clamp model to examine the involvement of the rise in core temperature in the functional immune modifications associated with prolonged exercise. Studies investigating the effects of cold, high altitude and microgravity on immunity and infection incidence are often hindered by extraneous stressors (e.g. isolation). Nevertheless, the available evidence does not support the popular belief that short- or long-term cold exposure, with or without exercise, suppresses immunity and increases infection incidence. In fact, controlled laboratory studies indicate immuno-stimulatory effects of cold exposure. Although some evidence shows that ascent to high altitude increases infection incidence, clear conclusions are difficult to make because of some overlap with the symptoms of acute mountain sickness. Studies have reported suppressed cell-mediated immunity in mountaineers at high altitude and in astronauts after re-entering the normal gravity environment; however, the impact of this finding on resistance to infection remains unclear.

Effects of temperature on phagocytosis of human and calf polymorphonuclear leukocytes

The in vitro effect of temperature on the phagocytic function of human and calf polymorphonuclear leukocytes (PMN) was studied. To observe the PMN phagocytic function (PPF) at various temperatures, PMN from healthy human and calf donors were incubated with serum-opsonized fluorescent latex particles (diameter 1.66 microns) at 25, 37, 40, 42, 44, or 46 degrees C for 1 h and then observed for their phagocytic activity by fluorescent microscopy. At 25, 40, and 42 degrees C, human PPF was not significantly different from that at 37 degrees C (87%, 89%, and 80% vs. 93%). At 44 degrees C, PPF was noticeably depressed (19%, p < 0.05) when compared to that at 37 degrees C. Next, to determine the critical temperature and duration of exposure that would irreversibly damage PPF, PMN were preincubated at 42, 44, or 46 degrees C for 5-30 min before being subjected to a standard phagocytosis assay at 37 degrees C. The human PPF was significantly depressed after 30 min at 44 degrees C (33%, p < 0.05) or 10 min at 46 degrees C (30%, p < 0.05). In conclusion, neither human nor calf PPF was significantly altered at and below 42 degrees C. In contrast, the PPF was irreversibly and time-dependently damaged when incubated at and above 44 degrees C.

Superoxide production of polymorphonuclear leukocytes in surgical patients with gastric cancer

Superoxide production (SOP) by polymorphonuclear leukocytes (PMNs) in 65 gastric cancer patients, who were in preoperative state and had received no medical therapy, was assayed in order to evaluate the bactericidal activity of PMNs in cancer patients, as well as to determine the correlation of SOP by PMNs with postoperative prognoses and several factors by which extent of disease and the clinical or histological character of gastric carcinoma were defined. Patients with stage II disease had a tendency to have an increased SOP by PMNs, and furthermore, as the disease progressed, the SOP by PMNs decreased with significant depression being noted in stage III and IV cases compared to healthy controls. Significantly reduced SOP by PMNs was observed in n2 and n3 cases and with se, si, sei and/or ps(+) pathological invasion. SOP by PMNs in patients with Borrmann II type and/or poorly differentiated adenocarcinoma was significantly depressed. Patients who suffered from septic complications showed a significant depression in SOP by PMNs compared with the controls and no complication group. These results suggest that advanced gastric cancer patients may have defective oxidative PMN metabolism, and that a decrease of SOP is a contributory cause of high susceptibility to postoperative infection in cancer patients.

Temperature elevation during brachytherapy for carcinoma of the uterine cervix: adverse effect on survival and enhancement of distant metastasis

Possible effects of fever during intracavitary radiation therapy on patient survival, local-regional control or metastatic spread of disease were analyzed in a group of 398 patients with previously untreated, invasive carcinoma of the uterine cervix, managed with a combination of external beam irradiation and intracavitary radium (ICR) applications at Yale-New Haven Medical Center and affiliated hospitals from January 1953 through December 1977. Cox step-wise proportional hazard models were used to test for the influence of elevated temperatures during ICR placements, controlling for the influence of other pretreatment patient parameters, including FIGO stage, age, blood count, prior supracervical hysterectomy and number of prior pregnancies. Increasing maximum temperatures noted during ICR placements were associated with: decreased patient survival (p = 0.014) and increased frequency with time of distant metastasis as the initial sites of treatment failure (p = 0.038). When patients were dichotomized on the basis of maximum temperature during ICR, distant metastasis as the initial site(s) of treatment failure was noted twice as frequently in patients with maximum temperatures greater than or equal to 101.0 degrees F (12.5%; 10/80 patients) than in those with maximum temperatures less than 101.0 degrees F during ICR placement (6.3%; 20/318 patients). No statistically significant differences were noted between the two groups in their distributions by stage, age, histology, year of diagnosis, or pretreatment hemoglobin, and the sites of distant metastasis and time course for clinical detection were similar in both groups. These results are in agreement with prior clinical studies in cancer of the uterine cervix which noted a poor prognosis in patients with cancer of cervix who developed fever during treatment. In addition, the finding of an association between an increased frequency of distant metastasis and temperature elevation during the ICR provides, for the first time, clinical data supporting the reports of an alteration or enhancement of distant metastasis following the application of whole body hyperthermia in murine, rabbit and canine tumors.

The effects of total-body hyperthermia combined with anticancer drugs on immunity in advanced cancer patients

As total-body hyperthermia (TBHT) therapy may lead to a reduction in the immune response of cancer patients because of the immediate effect of heat on lymphocytes, the authors studied the immunity of advanced cancer patients receiving combined TBHT and anticancer chemotherapy. A decrease was found in their lymphocyte blastogenesis, skin reactions to PPD and PHA, lymphocyte rosette formation, IgG, and C3c component. These parameters returned to their pretreatment levels at 1 week after completion of TBHT therapy. This result indicates that there is no necessity for giving special consideration to a reduction of cell-mediated immunity in TBHT therapy.

A comparison of the cytotoxic potential in polymorphonuclear leukocytes obtained from normal donors and cancer patients

Human polymorphonuclear leukocytes (PMNs) obtained from both normal donors and cancer patients kill human tumor cells in vitro. Furthermore, the PMNs were shown to exert a greater cytotoxic effect on malignant targets than they did on nonmalignant targets. In addition, colon and breast cancer patients with stage I disease were found to possess PMN cells which were less effective in killing the tumor cells than were the PMN cells from normal donors. In contrast, the colon and breast cancer patients with stage IV disease possessed PMN cells which were more effective than normal cells in killing the tumor targets. No clear cut trend was found for PMN cells obtained from breast and colon cancer patients diagnosed with stage II and III disease. However, it must also be noted that individual patients did not always conform to the group pattern.