Time-of-day effects on response of natural killer cells to acute stress in men and women

Rapid increase in immune surveillance and expression of NKT and γδT cell activation markers after consuming a nutraceutical supplement containing Aloe vera gel, extracts of Poria cocos and rosemary. A randomized placebo-controlled cross-over trial

GOAL

To evaluate the acute impact of a nutraceutical blend on immune surveillance.

STUDY DESIGN

A randomized, double-blind, placebo-controlled, cross-over trial was conducted in 11 healthy subjects. Blood samples were taken immediately before and at 1, 2, and 3 hours after consuming placebo or 500 mg of UP360, which is a blend of botanicals from Aloe vera, Poria cocos, and rosemary (APR extract). Immunophenotyping and flow cytometry quantified numbers of monocytes, NK cells, NKT cells, CD8+ cytotoxic T cells, γδT cells, and total T cells, and expression of CD25 and CD69 activation markers. Plasma was tested for cytokines, chemokines, growth factors, and enzymatic activity of superoxide dismutase and catalase.

RESULTS

Compared to the placebo, consumption of APR extract triggered rapid increases in chemokine levels starting at 1 hour, including IP-10 (P<0.05) and MCP-1 (P<0.1), which peaked at 2 hours (P<0.01) and 3 hours (P<0.05), respectively. The stem cell-mobilizing growth factor G-CSF increased at 2 hours (P<0.05). Increased immune surveillance involved a transient effect for monocytes at 1 hour, followed by NKT cells, CD8+ cytotoxic T cells, and γδT cells at 2-3 hours. Increased immune cell alertness was seen at 1 hour by increased CD25 expression on monocytes (P<0.01), NKT cells (P<0.01), and T cells (P<0.05). NKT cells showed upregulation of CD69 at 2 hours (P<0.01). Increased enzymatic activity was seen at 2 hours for the antioxidant enzymes superoxide dismutase (P<0.05) and catalase (P<0.01).

CONCLUSION

Consumption of APR extract triggered acute changes to chemokine levels. In addition, immune alertness was increased via the expression of activation markers on multiple types of innate immune cells, followed by increased immune surveillance and antioxidant protection. This suggests a beneficial enhancement of natural immune surveillance, likely via a combination of gut-mediated cytokine release and vagus nerve communication, in combination with cellular protection from oxidative stress.

Can natural killer cell activity help screen patients requiring a biopsy for the diagnosis of prostate cancer?

Purpose

To evaluate the usefulness of natural killer cell activity (NKA) in diagnosing prostate cancer (PC).

Materials and Methods

The medical records of patients who underwent transrectal prostate biopsy (TRBx) at Korea University Ansan Hospital between May 2017 and December 2017 were retrospectively reviewed. NKA levels were measured using NK Vue® Tubes (ATgen, Sungnam, Korea). All blood samples were obtained at 8 AM on the day of biopsy. Patients with other malignancies, chronic inflammatory conditions, high prostate-specific antigen (PSA) level (>20ng/mL), or history of taking 5-alpha-reductase inhibitor or testosterone replacement therapy were excluded.

Results

A total of 102 patients who underwent TRBx for PC diagnosis were enrolled. Among them, 50 were diagnosed with PC. Significant differences in age and NKA level were observed between the PC and no-PC groups. Receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off of NKA level for the prediction of PC was 500pg/dL, with a sensitivity of 68.0% and a specificity of 73.1%. In addition, NKA level (0.630) had the greatest area under the ROC curve compared to those for the ratio of total PSA to free PSA (0.597) and PSA density (0.578).

Conclusions

The results of this pilot study revealed that low NKA and high PSA levels were likely to be associated with a positive TRBx outcome. NKA detection was easy and improved the diagnostic accuracy of PC.

Affective immunology: where emotions and the immune response converge

Affect and emotion are defined as “an essential part of the process of an organism's interaction with stimuli.” Similar to affect, the immune response is the “tool” the body uses to interact with the external environment. Thanks to the emotional and immunological response, we learn to distinguish between what we like and what we do not like, to counteract a broad range of challenges, and to adjust to the environment we are living in. Recent compelling evidence has shown that the emotional and immunological systems share more than a similarity of functions. This review article will discuss the crosstalk between these two systems and the need for a new scientific area of research called affective immunology. Research in this field will allow a better understanding and appreciation of the immunological basis of mental disorders and the emotional side of immune diseases.

Secretory Ig a in Saliva and Academic Stress

Several reports have proposed that the concentration of secretory immunoglobulin A (S-IgA) in saliva is an indicator of psychological stress. With this in mind, we decided to examine it in 10 second year medical student volunteers at Kawasaki Medical School course between May 4 and July 13, 2000 and discussed the relationship between S-IgA and the stress from academic examinations. Saliva was collected three times (on rising, at forenoon, and at bedtime) every Thursday. During this period, sporadic academic examinations were held twice and term-end examinations occurred during the last two weeks. Results showed the concentration of S-IgA significantly higher at the on rising time-point than at the other two time-points. There was also a tendency for the S-IgA level in saliva to be higher on the day before academic examinations and during them and lower on the days between these examinations. In addition, daily variations in the S-IgA concentration sometimes seemed to be disturbed by other academic stress. Therefore, it may be possible to use this measurement to monitor psychological stress in students and workers.

Perturbation of secretory Ig A in saliva and its daily variation by academic stress

OBJECTIVES

Several studies have reported that the secretory immunoglobulin A (S-IgA) concentration in saliva is an indicator of psychological stress. The aim of this study was to clarify the relationship between S-IgA and the stress from academic examinations.

METHODS

S-IgA levels in 10 medical student volunteers from the second year course between May 4 and July 13, 2000 were examined using the ELISA method.

RESULTS

There was a tendency for S-IgA in saliva to be higher on the day before academic examinations and during them, and lower on the days between these examinations.

CONCLUSIONS

It may be possible to use this measurement to monitor psychological stress in students and workers.

Physical health problems after single trauma exposure: when stress takes root in the body

Research has established that chronic stress, including traumatic events, leads to adverse health outcomes. The literature has primarily used two approaches: examining the effect of acute stress in a laboratory setting and examining the link between chronic stress and negative health outcomes. However, the potential health impact of a single or acute traumatic event is less clear. The goal of this literature review is to extend the literature linking both chronic trauma exposure and posttraumatic stress disorder to adverse health outcomes by examining current literature suggesting that a single trauma may also have negative consequences for physical health. The authors review studies on health, including cardiovascular, immune, gastrointestinal, neurohormonal, and musculoskeletal outcomes; describe potential pathways through which single, acute trauma exposure could adversely affect health; and consider research and clinical implications.

An occupational health study of emergency physicians in Japan: health assessment by immune variables (CD4, CD8, CD56, and NK cell activity) at the beginning of work

This study was conducted to evaluate the occupational health of Japanese physicians in emergency medicine. Subjects participating in this study were eighty-nine physicians working at 12 medical facilities (10 critical care emergency centers) in Japan. Participants were asked to complete a questionnaire of work conditions and to provide blood samples for immune variable measurements (CD4, CD8, CD56 and natural killer cell (NK cell) activity) before commencing their work. The data collected from seventy-four of 89 participating physicians were analyzed. The traditional work group comprised of 39 emergency physicians, who were significantly overworked compared to other two groups: the shift work group and the day work group. Among these three groups, no immune variable was significantly different except lymphocyte, number of CD4, and NK cell activity; and the NK cell activity of the shift work group was significantly lower than those of the traditional work group (p<0.01) and the day work group (p<0.01) in terms of Bonferroni's multiple comparison, probably due to circadian rhythm. It was indicated that NK cell activity was significantly lower in samples collected at night versus in the morning (OR=8.34, 95%CI: 1.95-35.6, p<0.01) through multiple logistic regression analyses. NK cell activity was significantly lower in individuals taking 0-3 days off per month, as compared to those taking 4 or more days off (OR=4.65, 95%CI: 1.27-17.0, p=0.02), according to multiple logistic regression analyses. Therefore, the low NK cell activity appears to have reflected the extent of fatigue arising from physicians' overwork. Overwork would have been a potential risk for the physicians' health, resulting in a lower quality of Japanese emergency medical services than that which could have been achieved otherwise. This study suggests that it would be better for the Japanese emergency physicians to take 4 or more days off per month for their health and the quality of their services.

Immune, endocrine and cardiovascular responses to controllable and uncontrollable acute stress

This study, using a triadic-yoked design, clarified the effects of controllability of acute stress on responses of immune, cardiovascular (heart rate and blood pressure), and cortisol activities. Forty-three women in their follicular phase completed a mental arithmetic task as a stressor in which controllability was manipulated by correct or yoked-bogus feedback. The task decreased proportions of CD3+ T cells, CD4+ T cells, and CD19+ B cells, whereas it increased the numbers of white blood cells, lymphocytes, natural killer (NK) cells, and NK cell activity (NKCA). Our main hypothesis that greater immune and cardiovascular responses to the task would be obtained under the uncontrollable condition than under the controllable condition was not supported. However, the uncontrollable stress condition, but not the controllable situation, led to higher correlations between heart rate or blood pressure, and various immune parameters. On the other hand, parameters of heart rate variability reflecting sympathetic and parasympathetic activities showed significant correlations only with NKCA. These results suggest that immune responses were most directly associated with cardiovascular activities under the uncontrollable condition.

Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry

The present report meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. Acute stressors (lasting minutes) were associated with potentially adaptive upregulation of some parameters of natural immunity and downregulation of some functions of specific immunity. Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures. Effects of event sequences varied according to the kind of event (trauma vs. loss). Subjective reports of stress generally did not associate with immune change. In some cases, physical vulnerability as a function of age or disease also increased vulnerability to immune change during stressors.

Repeated endurance exercise affects leukocyte number but not NK cell activity

INTRODUCTION/PURPOSE

The purpose of this study was to determine the affects of repeated bouts of exercise in the same day on circulating leukocyte number and NK cell activity (NKCA).

METHODS

Ten males (18-25 yr of age) were chosen to complete four trials: two exercise bouts (TB), AM exercise (AM-EX), PM exercise (PM-EX), and control (CN) in a random, counter-balanced order. Exercise consisted of 1-h cycle ergometry, split into three, 20-min segments (5 min at 50% [V0](2peak) and 15 min at 70% [V0](2peak)), and was separated by a 4-h passive recovery. Blood samples were collected from a peripheral arm vein before, immediately, 2 h, and 24 h after the AM bout, and a second series was drawn for the PM bout. Leukocyte subpopulations were measured by manual counting using a hemacytometer and Wright-Giemsa-stained differential slides. NKCA was measured with a whole-blood 51Cr-release assay against K562 target cells. RESULTS Total leukocyte (13.2 +/- 1.2 x 109 L-1, P < 0.035) and neutrophil (7.6 +/- 0.7 x 109 L-1, P < 0.001) counts were significantly higher after two bouts of exercise than a single exercise bout completed in the morning (leukocyte: 7.8 +/- 0.7 x 109 L-1; neutrophil: 5.2 +/- 0.5 x 109 L-1) or afternoon (leukocyte: 9.9 +/- 0.8 x 109 L-1; neutrophil: 5.6 +/- 0.9 x 109 L-1). Lymphocyte counts were significantly greater (P < 0.001) after PM (4.2 +/- 0.5 x 109 L-1) than AM (3.7 +/- 0.4 x 109 L-1) exercise. NKCA was significantly greater (P < 0.001) after exercise in the afternoon (35.3 +/- 8.1%) than morning (27.2 +/- 5.9%).

CONCLUSION

PM exercise produced a larger increase in NKCA than AM exercise, possibly indicative of an interaction between exercise and a diurnal effect. These data suggest two bouts of endurance exercise in 1 d produce an "additive effect" for total leukocyte and neutrophil counts. and to a lesser degree lymphocyte counts, but did not appear to impact shifts in NKCA.

Reactivity and vulnerability to stress-associated risk for upper respiratory illness

OBJECTIVE

We tested the hypothesis that the greater a person's laboratory stress-elicited elevation in cortisol, the greater the life stress-related risk for upper respiratory infection (URI). We also tested the prediction that the greater the laboratory stress-elicited rise in natural killer cell (NK) cytotoxicity, the smaller the life stress-related URI risk. Finally, we explored whether sympathetic nervous system (SNS) and enumerative immune reactivities to laboratory stress moderate the relation between life stress and URI.

METHODS

At baseline, 115 healthy subjects were administered a negative stressful life events checklist and were tested to assess their SNS (blood pressure, heart rate, and catecholamines), HPA (cortisol), and immune (NK cell cytotoxicity and lymphocyte subsets) reactivities to laboratory speech tasks administered 2 weeks apart. Responses were averaged across the two laboratory assessments to create reactivity scores. After these assessments were completed, participants were followed weekly for 12 consecutive weeks. At each follow-up they completed a measure of perceived stress experienced over the last week. They were also instructed to contact the study coordinator if they had a cold or flu at any time during follow-up. A health care worker verified reported illnesses.

RESULTS

In a traditional prospective analysis, high cortisol reactors with high levels of life events had a greater incidence of verified URI than did high reactors with low levels of life events and low reactors irrespective of their life event scores. Using hierarchical linear modeling, CD8(+) number, Natural Killer (NK) cell number, and NK cell cytotoxicity, each interacted with weekly perceived stress levels in predicting concurrent occurrences of self-reported URIs. For these outcomes, low immune reactors were more likely to experience an URI during high stress than low stress weeks. High immune reactors did not exhibit differences in weekly URIs as a function of weekly stress level. The SNS reactivity markers did not moderate the association of stress and URI incidence in either analysis.

CONCLUSIONS

Acute HPA and immune responses to laboratory stressors are markers of how vulnerable people are to the increased risk for URI associated with stressors in the natural environment.