Capacity to produce cytokines during weight restoration in patients with anorexia nervosa

Growth factors in anorexia nervosa: a systematic review and meta-analysis of cross-sectional and longitudinal data

OBJECTIVES

Growth factors are signalling molecules that play roles in the survival, proliferation, migration, and differentiation of cells. Studies have found alterations in specific growth factors in anorexia nervosa (AN).

METHODS

This systematic review and meta-analysis examined articles from three databases, measuring growth factors in AN cross-sectionally and longitudinally, and in recovered AN (rec-AN) cross-sectionally. Random-effects meta-analyses were conducted for brain-derived neurotrophic factor (BDNF) and insulin growth factor-I (IGF-1) for cross-sectional and longitudinal studies.

RESULTS

A total of 82 studies were included: 56 cross-sectional (BDNF: n = 15; IGF-1: n = 41) and 24 longitudinal (BDNF: n = 5; IGF-1: n = 19) were meta-analysed and 20 studies were narratively synthesised. In cross-sectional analyses, BDNF and IGF-1 were lower in AN compared to controls, and BDNF was marginally greater in rec-AN compared to controls. In longitudinal meta-analyses, BDNF and IGF-1 increased from baseline to follow-up. Cross-sectional subgroup analyses revealed no differences in BDNF between controls and AN binge-eating/purging subtypes.

CONCLUSIONS

It is likely that the low BDNF and IGF-1 levels found in AN are consequences of starvation, which are reversible with weight restoration. The increase in BDNF and IGF-1 during therapeutic weight restoration might improve neuroplasticity, which is the basis of learning, and thus psychotherapeutic success.

A systematic review of in vitro cytokine production in eating disorders

BACKGROUND

Eating disorders (EDs) have been associated with alterations in cytokine concentrations and production. This review examines whether in vitro cytokine production (i) is altered in people with EDs compared to healthy participants; and (ii) changes in response to treatment?

METHODS

Using PRISMA guidelines, we systematically reviewed articles reporting group comparisons or longitudinal assessments of spontaneous and/or stimulated cytokine production in vitro in people with EDs.

RESULTS

Twelve studies were included. Cross-sectional results were mixed in anorexia nervosa. Only one study measured cytokine production in bulimia nervosa. Two longitudinal studies showed that daily yoghurt consumption increases phytohemagglutinin-stimulated interferon-γ production in anorexia nervosa.

CONCLUSION

The mixed results could be accounted for by variations in experimental design. Our findings suggest that cytokine production could possibly be modulated through dietary interventions. However, due to the methodological heterogeneity and shortcomings of the included studies, it seems unreasonable to draw further conclusions.

Can improvement in hormonal and energy balance reverse cardiovascular risk factors in athletes with amenorrhea?

Female athletes display a high prevalence of hypothalamic amenorrhea as a result of energy imbalance. In these athletes with amenorrhea, decreased luteinizing hormone/follicule-stimulating hormone secretion leads to deficiency in endogenous estrogen. The severe estrogen deficiency in these athletes may increase cardiovascular risk similar to that in postmenopausal women. This review discusses the potential cardiovascular risk factors in athletes with amenorrhea as a result of hypoestrogenism, which include endothelial dysfunction and unfavorable lipid profiles. We also consider the potential to reverse the cardiovascular risk by restoring energy or hormonal imbalance along the reproductive axis in athletes with amenorrhea.

Brain-Behavior-Immune Interaction: Serum Cytokines and Growth Factors in Patients with Eating Disorders at Extremes of the Body Mass Index (BMI) Spectrum

Alterations of the immune system are known in eating disorders (EDs), however the importance of cytokine balance in this context has not been clarified. We compared cytokines and growth factors at opposite ends of BMI ranges, in 90 patients classified in relation to BMI, depressive and EDs comorbidities. Serum concentrations of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) were determined by a biochip analyzer (Randox Labs). Differences were calculated through ANOVA. Possible predictors of higher cytokine levels were evaluated through regression analysis. IL-1α, IL-10, EGF, and IFN-γ were altered individuals with anorexia nervosa (AN) and binge eating disorder (BED). Night-eating was associated with IL-8 and EGF levels, IL-10 concentrations with post-dinner eating and negatively with sweet-eating, long fasting with higher IFN-γ levels. IL-2 increase was not linked to EDs, but to the interaction of depression and BMI. Altogether, for the first time, IL-1α, IL-10, EGF, and IFN-γ were shown to differ between AN and HCs, and between AN and individuals with obesity with or without BED. Only IL-2 was influenced by depression. Dysfunctional eating behaviors predicted abnormal concentrations of IL-10, EGF, IL-8 and IFN-γ.

Decline of Plasma Concentrations of Interleukin-18 in Severely Malnourished Patients with Anorexia Nervosa: Exploratory Analysis

Multiple studies on the dynamics of inflammatory cytokines in patients with anorexia nervosa (AN) have been published, although results are not consistent among reports. Thus the pathophysiologic roles of these cytokines are not clear. We performed an exploratory analysis that included (1) comparisons of plasma interleukin-18 (IL-18) concentrations between patients with AN (n = 21) and healthy controls (n = 39), and (2) correlations between body mass index (BMI) and IL-18 concentrations in both groups, exploring the relationship between malnourishment and IL-18. Plasma IL-18 levels were significantly decreased in patients with AN compared with controls. Plasma IL-18 levels correlated to BMI in controls, but not in patients with AN. These results suggest that a decline in plasma IL-18 levels in patients with AN is not only due to malnourishment, but other pathophysiologic changes as well. IL-18 has a role in the brain’s reaction to sadness and chronic stress. Therefore, decreased levels of IL-18 may commonly occur in patients with chronic AN.

Immune disorders in anorexia

Anorexia nervosa is a disease involving eating disorders. It mainly affects young people, especially teenage women. The disease is often latent and occurs in many sub-clinical and partial forms. Approximately from 0.3% to 1% of the population suffers from anorexia. It has been shown that patients with anorexia develop neurotransmitter-related disorders, leading to uncontrolled changes in the immune and endocrine systems. Interactions between cytokines, neuropeptides, and neurotransmitters play an important role in disease development. Significant malnutrition induces disorders and alterations in T-cell populations. The cellular response in patients with anorexia nervosa has been shown to be normal, although opinions on this issue are controversial. Laboratory studies on neutrophils in anorexia patients showed decreased adhesion and reduced bactericidal and cell activities. Despite such unfavourable results, patients with anorexia are resistant to infections, which are very rare in this group. Glutamine improves the performance of the human immune system. The administration of glutamine to anorexia patients, as a supplement to parenteral nutrition, has resulted in significant improvements in immune system parameters. The results of previous studies on the causes and risk factors in the development of anorexia nervosa are still ambiguous. One can hope that the differences and similarities between patients with anorexia nervosa and those with other forms of protein-calorie malnutrition may be helpful in determining the relationship between nutritional status and body defences and susceptibility to infection, and can help to broaden the knowledge about the aetiopathogenesis of anorexia nervosa.

Increased naive CD4+ and B lymphocyte subsets are associated with body mass loss and drive relative lymphocytosis in anorexia nervosa patients

Anorexia nervosa (AN) is an atypical form of malnutrition with peculiar changes in the immune system. We hypothesized that different lymphocyte subsets are differentially affected by malnutrition in AN, and thus, our aim was to investigate the influence of body mass loss on the variability of lymphocyte subsets in AN patients. A group of 66 adolescent female patients, aged 12-17 years, referred for their first episode of either AN or feeding or eating disorders not elsewhere classified were studied upon admission (46 AN-restricting subtype, 11 AN-binge/purging subtype, and 9 feeding or eating disorders not elsewhere classified). Ninety healthy adolescents served as controls. White blood cells and lymphocyte subsets were analyzed by flow cytometry. Relationships with the body mass index (BMI) z score were assessed in linear models adjusted by diagnostic subtype and age. Leukocyte numbers were lower in AN patients than in controls, and relative lymphocytosis was observed in AN-restricting subtype. Lower CD8⁺, NK, and memory CD8⁺ counts were found in eating disorder patients compared with controls. No differences were found for CD4⁺ counts or naive and memory CD4⁺ subsets between the groups. Negative associations between lymphocyte percentage and the BMI z score, as well as between the B cell counts, naive CD4⁺ percentage and counts, and the BMI z score, were found. In conclusion, increased naive CD4⁺ and B lymphocyte subsets associated with body mass loss drive the relative lymphocytosis observed in AN patients, which reflects an adaptive mechanism to preserve the adaptive immune response.

Refeeding Low Weight Hospitalized Adolescents With Anorexia Nervosa: A Multicenter Randomized Controlled Trial

BACKGROUND

Refeeding patients with anorexia nervosa (AN) is associated with high morbidity and mortality. A lack of evidence from interventional studies has hindered refeeding practice and led to worldwide disparities in management recommendations. In the first randomized controlled trial in this area, we tested the hypothesis that refeeding adolescents with AN with a higher energy intake than what many guidelines recommend improved anthropometric outcomes without adversely affecting cardiac and biochemical markers associated with refeeding.

MATERIALS AND METHODS

Participants aged 10-16 years with a body mass index (BMI) <78% of the median (mBMI) for age and sex were recruited from 6 UK hospitals and randomly allocated to start refeeding at 1200 kcal/d (n = 18, intervention) or 500 kcal/d (n = 18, control).

RESULTS

Compared with controls, adolescents randomized to high energy intake had greater weight gain (mean difference between groups after 10 days of refeeding, -1.2% mBMI; 95% confidence interval, -2.4% to 0.0%; P = .05), but randomized groups did not differ statistically in QTc interval and other outcomes. The nadir in postrefeeding phosphate concentration was significantly related to percentage mBMI at the start of refeeding (baseline; P = .04) and baseline white blood cell count (P = .005) but not to baseline energy intake (P = .08).

CONCLUSIONS

Refeeding adolescents with AN with a higher energy intake was associated with greater weight gain but without an increase in complications associated with refeeding when compared with a more cautious refeeding protocol-thus challenging current refeeding recommendations.

Greater impact of dietary fat manipulation than apolipoprotein E genotype on ex vivo cytokine production - insights from the SATgenε study

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The effect of diet and genotype on inflammatory response was explored in humans.

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Cytokine production was not affected by apolipoprotein E (APOE) genotype.

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TNF-α concentration significantly increased after a high saturated fat diet.

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IL-10 concentration was significantly higher after a low fat diet.

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The amount and type of dietary fat modulated cytokine production.

Apolipoprotein E (APOE) genotype is believed to play an important role in cardiovascular risk. APOE4 carriers have been associated with higher blood lipid levels and a more pro-inflammatory state compared with APOE3/E3 individuals. Although dietary fat composition has been considered to modulate the inflammatory state in humans, very little is known about how APOE genotype can impact on this response. In a follow-up to the main SATgenε study, we aimed to explore the effects of APOE genotype, as well as, dietary fat manipulation on ex vivo cytokine production. Blood samples were collected from a subset of SATgenε participants (n = 52/88), prospectively recruited according to APOE genotype (n = 26 E3/E3 and n = 26 E3/E4) after low-fat (LF), high saturated fat (HSF) and HSF with 3.45 g docosahexaenoic acid (DHA) dietary periods (each diet eight weeks in duration assigned in the same order) for the measurement of ex vivo cytokine production using whole blood culture (WBC). Concentrations of IL-1beta, IL-6, IL-8, IL-10 and TNF-alpha were measured in WBC supernatant samples after stimulation for 24 h with either 0.05 or 1 μg/ml of bacterial lipopolysaccharide (LPS). Cytokine levels were not influenced by genotype, whereas, dietary fat manipulation had a significant impact on TNF-α and IL-10 production; TNF-α concentration was higher after consumption of the HSF diet compared with baseline and the LF diet (P < 0.05), whereas, IL-10 concentration was higher after the LF diet compared with baseline (P < 0.05). In conclusion, our study has revealed the amount and type of dietary fat can significantly modulate the production of TNF-α and IL-10 by ex vivo LPS-stimulated WBC samples obtained from normolipidaemic subjects.

The hematology of anorexia nervosa

OBJECTIVE

Changes of the peripheral blood cell count in patients with anorexia nervosa (AN) are frequent. Anemia and leukopenia are observed in one-third of these patients. Examination of the bone marrow reveals in almost 50% of the patients with AN signs of bone marrow atrophy and can additionally suffer from a gelatinous bone marrow transformation.

METHOD

Published studies and investigations concerning hematological changes in patients with AN were reviewed.

RESULTS

Anemia and mild neutropenia are detectable in almost one-third of these patients, whereas thrombocytopenia is rather uncommon. The exact mechanism for these findings is still unclear, but 50% of AN-patients with hematological changes display morphological signs of partial bone marrow atrophy.

DISCUSSION

Changes of the peripheral blood cell count in patients with AN is a frequent observation but the peripheral blood cell count cannot predict the severity of bone marrow atrophy. All hematological and morphological alterations disappear completely and rapidly after sufficient refeeding.

Immunological disturbance and infectious disease in anorexia nervosa: a review

OBJECTIVE

Severely malnourished patients with anorexia nervosa (AN) are reported to show fewer symptomatic viral infections and a poorer response to bacterial infection than controls. They are also reported to show mild immune system changes, although the relevance of these to altered infection disease presentation in AN and AN pathophysiology is unknown. Thus, in this paper, we suggest a range of immune system changes that might underpin these altered responses to common pathogens, and review a number of recent infectious disease findings for their utility in explaining the pathophysiology of AN.

METHODS

A systematic review of the literature pertaining to immunity and infectious disease in AN was performed.

RESULTS

AN is associated with leucopenia, and the increased spontaneous and stimulated levels of proinflammatory cytokines [i.e. interleukin (IL)-1β, IL-6 and tumour necrosis factor α). A range of less consistent findings are also reviewed. Most of these data were not controlled for length of illness, degree of malnutrition, micronutrient or vitamin deficiencies or recent refeeding and starvation.

CONCLUSION

Cytokine disturbances have been suggested to be causally related to AN symptomatology and pathophysiology of AN, although the evidence supporting this assertion is lacking. Immune and cytokine changes in AN do, however, occur in association with a decreased incidence of symptomatic viral infection, decreased clinical response to bacterial infection leading to delayed diagnosis and increased morbidity and mortality associated with the infections.

Low insulin-like growth factor I and leukopenia in anorexia nervosa

OBJECTIVE

Considering that leukopenia and anemia are commonly observed in anorexia nervosa (AN) and that growth hormone (GH) and insulin-like growth factor-I (IGF-I) markedly influence the activation, growth and survival of hemopoietic cells, we sought for possible relationships between hematologic parameters and the GH-IGF-I axis in a group of patients with AN.

METHOD

Twenty patients were studied. Leukocyte and erythrocyte counts, as well as baseline serum GH levels and IGF-I standard deviation score (SDS) values, were determined in each participant and correlations between parameters were searched.

RESULTS

Leukocyte and erythrocyte counts, as well as IGF-I SDS values, were significantly lower, conversely GH was significantly higher in AN patients than in normal weight participants. In patients, IGF-I SDS values were positively correlated with leukocyte count and BMI, whereas no correlation was found between IGF-I SDS and hemoglobin or erythrocytes.

CONCLUSION

The demonstration of a positive correlation between leukocyte number and circulating IGF-I in AN suggests a likely pathogenetic role of IGF-I deficiency in this hematologic abnormality.

Cytokine production by blood mononuclear cells from in-patients with anorexia nervosa

Although protein–energy malnutrition is a common cause of immunodeficiency, the immune function in underweight anorexia nervosa (AN) patients usually seems to be better preserved than would be expected. However, a deranged cytokine production and its consequences are currently being investigated in these patients. This study was aimed at measuring, over time, the capacity of peripheral blood mononuclear cells (PBMC) from AN in-patients to produce several cytokines involved in the regulation of immune responses. The in vitro production of interferon (IFN)-γ, interleukin (IL)-2, tumour necrosis factor (TNF)-α, IL-6 and IL-1β by phytohaemagglutinin-stimulated PBMC were assessed on forty female adolescents with AN. These measures were carried out twice, upon hospital admission and at discharge, which occurred on average after 1 month. Thirty-five control subjects were also studied. Cytokines were measured by ELISA kits. The production of TNF-α and IL-6 was lower and production of IL-1β higher in AN patients than in the control group at both time points of assessment. Refeeding for 1 month was not enough time to reverse these differences and patients still had a low body weight at discharge. IFN-γ production was lower in the patients than in control subjects only at discharge and no differences were found in IL-2 production between both groups. The results suggest that a mechanism involving modifications in the secretion pattern of proinflammatory cytokines could explain some immune function findings in underweight AN patients.

Investigation of regulatory T cells in anorexia nervosa

OBJECTIVE

The aim of our study was to determine, how severe calorie restriction in anorexia nervosa (AN) may influence regulatory T (Treg) cells and their cellular networks, that is, their main inducers (dendritic cells (DC) and monocytes) and their target cells, CD4+ lymphocytes.

DESIGN

We measured the prevalence of Tregs, myeloid and plasmocytoid DC. The prevalence of tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-12-positive monocytes, IL-2, IL-4 and interferon (IFN)-gamma positive CD4+ cells was determined by intracellular staining after activation.

SETTING AND SUBJECTS

In total, 21 AN patients and 19 healthy age-matched controls (body mass index values, median (range): 14.9 (11.1-17.4) vs 23.2 (19.5-27.4) kg/m(2)) have been recruited.

RESULTS

Prevalence of Tregs, DCs, TNF-alpha and IL-12-positive monocytes, IL-4 and IFN-gamma-producing CD4+ cells were similar in AN and controls. The prevalence of IL-2-positive CD4+ cells was somewhat lower in AN (% value, median (range): 12.05 (7.50-16.70) vs 14.40 (12.00-22.00), P<0.05). None of these parameters correlated with the patients' clinical characteristics.

CONCLUSIONS

Our results suggest that the antigen presenting cell - regulatory T cell - CD4+ lymphocyte axis is not affected by calorie and nutritional deficiency.

Changes in heart rate with refeeding in anorexia nervosa: a pilot study

OBJECTIVE

To find differences in heart rate before and after refeeding and to identify which parameters of autonomic activity and endocrine function are associated with these differences.

METHODS

Before and after the start of refeeding, body weight, RR interval (RRI), heart rate variability, endocrine function, and energy expenditure were measured in nine female anorexia nervosa patients.

RESULTS

After short-term refeeding, mean daytime heart rate rose from 54.9 to 69.4 bpm (P<.05). The changes in sympathetic activity were correlated negatively with the changes in RRI (r=-.933, P<.001). Urine C-peptide, IGF-1, and fT3 increased significantly, and norepinephrine tended to increase.

CONCLUSION

We demonstrated that autonomic nervous activity was relevant to changes in heart rate during refeeding, and it is speculated that the increases in insulin secretion, thyroid function, and IGF-1 were responsible for the mechanisms.

What is new in cytokine research related to trauma/critical care

Cytokines are low molecular weight proteins whose production can be modified by various insults. They have the potential to modify cellular responses to these insults. Recent years have seen a plethora of research in cytokine biology in trauma and critical care.

Changes in cytokine production and impaired hematopoiesis in patients with anorexia nervosa: the effect of refeeding

The changes in cytokines and hormones involved in hematopoiesis were studied in the serum of 7 girls with anorexia nervosa, 15-24 yr old, on admission and after 5% and 10% weight gain. Hematopoiesis was studied by in-vitro culturing of circulating granulocyte-macrophage colony forming cells and erythroid burst forming cells. Nutritional status was studied by anthropometric measurements and resting energy expenditure. On admission, granulocyte-macrophage colony forming cells and erythroid burst forming cells were significantly lower than in age-matched controls and increased significantly along weight gain. Blood leptin and erythropoietin levels increased significantly with weight gain. TNF-alpha levels tended to decrease while IL-1beta levels were lower than in the controls on admission (p <0.05) and did not change significantly during weight gain. IL-3, GM-CSF and IL-6 were undetected on admission or along weight gain. The changes in granulocyte-macrophage colony forming cells and erythroid burst forming cells positively correlated with changes in resting energy expenditure and fat free mass. These results may suggest that undernutrition affects hematopoiesis as indicated by the reduction of hematopoietic progenitor cells before treatment and the significant increase with weight gain. The changes in the levels of hormones and cytokines known to be involved in hematopoiesis along refeeding may suggest a role for these factors in anorexia nervosa.

Reduced febrile response to bacterial infection in anorexia nervosa patients

OBJECTIVE

To report a reduced febrile response to bacterial infections in anorexia nervosa (AN) patients.

METHOD

Four cases were obtained from a retrospective review of charts from the St. Paul's Hospital Eating Disorders Program (Vancouver, Canada). The patients had died or had been admitted to the hospital for treatment of a bacterial infection. In addition, one case was obtained from the Royal Prince Alfred Hospital (Sydney, Australia).

RESULTS

All patients suffered a bacterial infection during the course of AN. None of the patients had a temperature higher than 37 degrees C during the infectious illness.

DISCUSSION

The absence of fever in AN may delay the diagnosis of bacterial infection and may be a marker of an impaired immune response. Therefore, alternative methods of investigation are necessary in patients with AN suspected of having a bacterial infection.

Involvement of cytokines in eating disorders: a critical review of the human literature

A number of findings from clinical and animal studies indicate that pro-inflammatory cytokines may play roles in eating disorders. The measurement of pro-inflammatory cytokines (IL-1, IL-6, TNFalpha), which are known to decrease food intake, provides highly variable data from which firm conclusions cannot be drawn. In most of the longitudinal studies where pro-inflammatory cytokines have been shown to be impaired in anorexia or bulimia nervosa, a return to normal values was observed after renutrition. However these findings do not exclude the possibility that pro-inflammatory cytokines might be overproduced in specific brain areas and act locally without concomitantly increased serum or immune production. It was also pointed out that the production of the major type-1 cytokines (especially IL-2) was depressed in anorexia nervosa. It remains unclear whether this is due to undernutrition or to a specific underlying cause common to eating disorders. The impaired cytokine profile observed in eating disorders could be related to several factors including impaired nutrition, psychopathological and neuroendocrine factors. More particular attention should be devoted to the deregulation of the anti/pro-inflammatory balance. Deregulation of the cytokine network may be responsible for medical complications in eating disorder patients who are afflicted with chronic underweight.

Physiologic regulators of bone turnover in young women with anorexia nervosa

OBJECTIVE

To clarify the role of physiologic regulators of bone turnover in patients with anorexia nervosa (AN).

STUDY DESIGN

Adolescent girls with AN (n = 61) had anthropometric, nutrition, and exercise data acquired, and bone mineral density (BMD) and body composition measured by dual energy x-ray absorptiometry. Serum samples were obtained for hormones, proresorptive cytokines, and bone formation markers, and urine for bone resorption markers.

RESULTS

In bivariate correlation analyses, significant (P <.05) predictors of lumbar BMD included height, weight, and exercise. In multiple regression models, these significant relationships held, even after controlling for the duration of amenorrhea and AN. For total body BMD, the same positive predictors were found and percentage of body fat was a negative correlate. For hip BMD, exercise and weight were found to be positive predictors. Dehydroepiandrosterone sulfate (DHEAS) was inversely correlated with N-telopeptides (NTx), and insulin-like growth factor I (IGF-I) was directly correlated with osteocalcin. Proresorptive cytokine levels were low or undetectable.

CONCLUSIONS

Exercise and weight were positive predictors of BMD. These data are the first to suggest a relationship between DHEAS and increased bone resorption in AN. IGF-I was correlated with bone formation indices. Low cytokine levels suggest that these factors do not mediate the increased bone resorption of AN.

Psychoneuroimmunology and psychosomatic medicine: back to the future

OBJECTIVE

Although psychological modulation of immune function is now a well-established phenomenon, much of the relevant literature has been published within the last decade. This article speculates on future directions for psychoneuroimmunology research, after reviewing the history of the field.

METHODS

This review focuses on human psychoneuroimmunology studies published since 1939, particularly those that have appeared in Psychosomatic Medicine. Studies were clustered according to key themes, including stressor duration and characteristics (laboratory stressors, time-limited naturalistic stressors, or chronic stress), as well as the influences of psychopathology, personality, and interpersonal relationships; the responsiveness of the immune system to behavioral interventions is also addressed. Additionally, we describe trends in populations studied and the changing nature of immunological assessments. The final section focuses on health outcomes and future directions for the field.

RESULTS

There are now sufficient data to conclude that immune modulation by psychosocial stressors or interventions can lead to actual health changes, with the strongest direct evidence to date in infectious disease and wound healing. Furthermore, recent medical literature has highlighted a spectrum of diseases whose onset and course may be influenced by proinflammatory cytokines, from cardiovascular disease to frailty and functional decline; proinflammatory cytokine production can be directly stimulated by negative emotions and stressful experiences and indirectly stimulated by chronic or recurring infections. Accordingly, distress-related immune dysregulation may be one core mechanism behind a diverse set of health risks associated with negative emotions.

CONCLUSIONS

We suggest that psychoneuroimmunology may have broad implications for the basic biological sciences and medicine.