To assess, to control, to exclude: effects of biobehavioral factors on circulating inflammatory markers

LPS-induced whole-blood cytokine production and depressive symptoms in dementia spousal caregivers: The moderating effect of childhood trauma

Dementia spousal caregivers are at risk for adverse mental and physical health outcomes. Caregiver burden, anticipatory grief, and proinflammatory cytokine production may contribute to depressive symptoms among caregivers. People who report childhood trauma are more likely to have exaggerated stress responses that may also contribute to depressive symptoms in adulthood. This study aimed to test whether the relationship between whole-blood cytokine production and depressive symptoms is strongest in caregivers who report high levels of childhood trauma.

METHODS

A sample of 103 dementia spousal caregivers provided self-report data on demographics, health information, caregiver burden, anticipatory grief, and depressive symptoms. We also determined lipopolysaccharide-induced whole-blood cytokine production as the primary measure of immune cell reactivity. We measured interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) and converted z-scores of each cytokine into a composite panel. We regressed depressive symptoms on proinflammatory cytokine production, caregiver burden, and anticipatory grief, adjusting for demographic and health-related covariates.

RESULTS

Whole-blood cytokine production and childhood trauma were associated with depressive symptoms. Childhood trauma moderated the relationship between whole-blood cytokine production and depressive symptoms. Whole-blood cytokine production was only associated with depressive symptoms at mean and high levels of childhood trauma, but not at low levels of childhood trauma. The main effects of burden and anticipatory grief on depressive symptoms were strongest for caregivers reporting high levels of childhood trauma.

DISCUSSION

Childhood trauma has lasting impacts on psychosocial experiences later in life and has effects that may confer susceptibility to inflammation-related depression. Our findings contribute to ongoing efforts to identify risk factors for adverse mental health in dementia spousal caregivers.

Higher inflammatory proteins predict future depressive symptom severity among adolescents with lower emotional clarity

BACKGROUND

A growing body of work has implicated inflammation in the pathogenesis of depression. As not all individuals with heightened levels of peripheral inflammation develop symptoms of depression, additional work is needed to identify other factors that catalyze the relationship between inflammation and depressive symptoms. Given that elevated levels of inflammatory activity can induce a variety of emotional changes, the present study examined whether emotional clarity, the trait-like ability to identify, discern, and express one's emotions, influences the strength of the association between inflammatory signaling and concurrent and prospective symptoms of depression.

METHODS

Community adolescents (N = 225, Mage = 16.63 years), drawn from a larger longitudinal project investigating sex and racial differences in depression onset, provided blood samples to determine peripheral levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) at a baseline visit, along with self-report measures of emotional clarity and depressive symptom severity. Depressive symptom severity was assessed again at a follow-up visit approximately 5-months after baseline.

RESULTS

Hierarchical multiple regressions detected a significant interaction between inflammatory markers and emotional clarity on future depression severity, controlling for baseline depressive symptoms. Specifically, among adolescents with low levels of emotional clarity, higher levels of IL-6, CRP, and inflammatory composite scores were significantly associated with greater future depression severity.

CONCLUSIONS

These results indicate that low emotional clarity and high inflammatory signaling may jointly confer risk for prospective depressive symptom severity among adolescents. Therapeutic interventions that improve emotional clarity may reduce risk of depressive symptoms among adolescents with low-grade peripheral inflammation.

Examining the moderating role of cannabis use on the relationship between alcohol consumption and inflammation in individuals with alcohol use disorder

Inflammation appears to be a critical mechanism in the development of alcohol use disorder (AUD) and a consequence of chronic alcohol use. The potential anti-inflammatory properties of cannabis may modulate the proinflammatory effects of alcohol. This study sought to extend previous work investigating the relationship between alcohol consumption, cannabis use and circulating interleukin (IL)-6 levels in a sample with AUD. One hundred and thirty-three individuals with an AUD provided blood samples to assess IL-6 and answered questions regarding alcohol and cannabis use. An ordinary least squares multiple regression analysis was conducted to assess the effect of alcohol and cannabis use on IL-6. A moderation analysis examined cannabis use as a potential moderator of the relationship between alcohol use and circulating IL-6 levels. Alcohol use was predictive of higher log IL-6 levels (standardized β = 0.16, p = 0.03), while cannabis use was not predictive of log IL-6 levels (p = 0.36). Days of cannabis use moderated the relationship between alcohol use and IL-6 levels, such that the relationship between alcohol use and IL-6 levels was only significant in individuals with AUD without recent cannabis use. This study extends previous work to a clinical sample with an AUD and underscores the importance of considering cannabis use in studies on alcohol use and inflammation. This study also indicates the need for in-depth analyses on cannabinoids and inflammation and the interaction between cannabinoids and alcohol use on inflammation.

Multidimensional Religiousness and Spirituality Are Associated With Lower Interleukin-6 and C-Reactive Protein at Midlife: Findings From the Midlife in the United States Study

BACKGROUND

Religiousness and spirituality (R/S) are associated with lower morbidity and mortality, yet the physiological mechanisms underlying these associations are under-studied. Chronic inflammation is a plausible biological mechanism linking R/S to downstream health given the sensitivity of the immune system to the social environment and the role of inflammation in many chronic diseases.

PURPOSE

The purpose of the present study was to examine associations between multiple R/S dimensions and two markers of chronic inflammation, interleukin-6 (IL-6) and C-reactive protein (CRP).

METHODS

In this cross-sectional study, data came from biological subsamples of two cohorts from the Midlife in the United States (MIDUS) Study (combined N = 2,118). Predictors include six R/S measures (service attendance, spirituality, private religious practices, daily spiritual experiences, religious coping, and R/S-based mindfulness). Outcomes include log-transformed IL-6 and CRP. Covariates include age, gender, cohort, race, educational attainment, body mass index (BMI), smoking status, and physical activity.

RESULTS

Older adults, women (vs. men), non-White (vs. White) adults, those with higher BMIs, current smokers, and those not meeting physical activity guidelines had significantly higher IL-6 and CRP. In fully adjusted models, greater spirituality, daily spiritual experiences, religious coping, and R/S-based mindfulness were associated with lower IL-6. Higher spirituality was also associated with lower CRP.

CONCLUSIONS

Many dimensions of R/S may be health protective for adults given their associations with lower levels of chronic inflammation. Findings underscore the importance of examining multiple dimensions of R/S to understand mechanistic pathways.

Salivary inflammatory biomarkers as a predictor of post-traumatic stress disorder and depressive symptom severity in trauma patients: A prospective study

BACKGROUND

Although post-traumatic stress disorder (PTSD) and depression screening are recommended for traumatic injury patients, routine screening is still uncommon. Salivary inflammatory biomarkers have biological plausibility and potential feasibility and acceptability for screening. This study tested prospective associations between several salivary inflammatory biomarkers (proinflammatory cytokines interleukin-1β, interleukin-6, tumor necrosis factor-α; and C-reactive protein), collected during hospitalization and PTSD and depressive symptoms at 5-month follow-up.

METHODS

Adult traumatic injury patients (N = 696) at a major urban Level 1 trauma center provided salivary samples and completed PTSD and depressive symptom measures during days 0-13 of inpatient hospitalization. At 5-month follow-up, 368 patients (77 % male, 23 % female) completed the Clinician-Administered PTSD Scale for DSM-IV and the Self-rated Inventory of Depressive Symptomatology. Analyses focused on a latent inflammatory cytokine factor and C-reactive protein at baseline predicting 5-month PTSD and depression symptom outcomes and included baseline symptom levels as covariates.

RESULTS

A latent factor representing proinflammatory cytokines was not related to 5-month PTSD or depressive symptom severity. Higher salivary CRP was related to greater PTSD symptom severity (β = .10, p = .03) at 5-month follow-up and more severity in the following depressive symptoms: changes in weight and appetite, bodily complaints, and constipation/diarrhea (β's from .14 to .16, p's from .004 -.03).

CONCLUSION

In a primarily Latine and Black trauma patient sample, salivary CRP measured after traumatic injury was related to greater PTSD symptom severity and severity in several depressive symptom clusters. Our preliminary findings suggest that salivary or systemic CRP may be useful to include in models predicting post-trauma psychopathology.

When High Subjective Social Status Becomes a Burden: A Japan-U.S. Comparison of Biological Health Markers

High subjective social status (SSS) is believed to protect health in the current literature. However, high SSS entails social responsibilities that can be stressful in collectivistic cultural contexts. Here, we tested the hypothesis that those socialized in collectivistic societies (e.g., Japan) recognize their high social status as entailing social duties difficult to ignore even when they are excessive. Using cross-cultural survey data (N = 1,289) and a measure of biological health risk (BHR) by biomarkers of inflammation and cardiovascular malfunction, we found that higher SSS predicted lower BHR for American males. In contrast, higher SSS predicted higher BHR for Japanese males, mediated by the perceived difficulty of disengaging from their current goals. In both cultural groups, females showed no association between SSS and BHR. These findings suggest that social status has differing health implications, depending on the relative salience of privileges and burden-producing responsibilities in different cultural contexts.

Szabo Y. Childhood Adversity and Adult Inflammation: Exploring the Mediating Role of Emotion Regulation in the MIDUS II Study

The present study furthers understanding of how childhood adversity connects to inflammation and, in turn, poor health. Using the publicly available Midlife in the United States II (MIDUS II) dataset, we test a recent theoretical model that suggests emotion regulation is a potential mechanism of associations between adversity and inflammation. We examined the indirect effects of various types of adversity (e.g., stressful events, maltreatment, threat, and deprivation) on inflammation via two emotion regulation strategies (i.e., expressive suppression and reappraisal). Participants included 1096 adults without a history of cancer or HIV/AIDS who had completed the initial MIDUS II follow up and a sub-study examining biomarkers. Participants completed self-report measures inquiring about psychosocial factors including stressful life events, childhood trauma, and emotion regulation as well as provided blood samples. Bivariate correlation indicated that multiple forms of childhood adversity were associated with both C-reactive protein and fibrinogen. Deprivation, as measured by a stressful life events scale, was positively associated with both reappraisal and suppression. Tests of indirect effects indicated that deprivation was positively associated with fibrinogen through both emotion regulation strategies, particularly for female participants. Our findings partially support recent theory positing emotion regulation as a pathway through which childhood adversity may impact inflammation in adulthood. Further, deprivation may be particularly critical in understanding how adversity is connected to maladaptive emotion regulation and inflammation. Emotion regulation may be an important treatment target to mitigate the negative impact of childhood adversity on health and well-being.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40653-023-00594-2.

Psychosocial predictors of the innate immune response to influenza vaccination

Experimental activation of the innate immune system has contributed significantly to both our understanding of how psychological factors influence immune function as well as how immune activity influences the brain and behavior. The annual influenza vaccine can be used to interrogate the effects of mild immune stimulation on day-to-day changes in psychological processes in human subjects that range across the lifespan and in both clinical and non-clinical populations. Yet, the immune response to the influenza vaccine in the days immediately following its administration are not well characterized. The present study describes changes in inflammatory and antiviral gene expression within circulating immune cells, plasma cytokines, and C-reactive protein (CRP) following receipt of the flu vaccine, and further reports the association between several common behavioral health factors and the acute immune response. Participants were 65 adults (mean age 18.81 ± 1.03 years; 66.2% female) who provided a blood sample immediately before and then 24 h after receiving the vaccine. A subsample also provided additional blood samples at 48 and 72 h. Plasma was assayed for CRP, IL-6, IL-10, IL-8, TNF-α, and IFN-γ, and peripheral blood mononuclear cell RNA was sequenced for evidence of change in expression of an a priori set of type 1 interferon (IFN) and inflammatory response genes (INFLAM). Plasma cytokines, CRP, and IFN response genes increased 24 h after vaccination, all ps < .001. The increase in IFN gene expression correlated with the observed increase in plasma cytokines and CRP, p < .0001. The immune response to influenza vaccination at 24-hours was moderated by anxiety symptoms, BMI, being female, sleep, and history of influenza vaccination. These factors and their associations with common immune challenges may be useful in studies interrogating the origins of immune dysregulation. The annual influenza vaccine is an accessible and reliable exogenous activator of both circulating and transcriptional markers of innate immune reactivity, with sensitivity to behavioral health factors relevant for psychoneuroimmunology research.

Repetitive thought, cognition, and systemic inflammation in the midlife in the United States study

OBJECTIVE

Poor cognition increases risk for negative health outcomes, and this may be explained by associations with systemic inflammation. Previously, amount of repetitive thought (Total RT) interacted with IQ to predict interleukin-6 (IL-6) in older adults. This study continued the investigation of repetitive thought (RT) as an element involved in the effect of cognition on inflammation.

DESIGN

Participants (N = 164) came from the Midlife in the United States Refresher project (Mage = 45.33, SD = 11.51, ranges = 25-74; 48.2% female; 85% Caucasian). Cognition was assessed via telephone, inflammatory biomarkers (IL-6, C-reactive protein (CRP), and tumour-necrosis factor-alpha (TNF- α)) analysed after blood draw, and RT derived from daily diary data.

RESULTS

Cognition significantly interacted with RT valence (p = .009) to explain CRP after covariate adjustment. Better cognition and more negative RT valence was associated with lower CRP (β = -0.190 [-.387, .008]). Worse cognition and more negative RT valence was associated with higher CRP (β = 0.133 [-.031, .297]). No significant effects were found for IL-6 or TNF-α.

CONCLUSION

RT may interact with cognition to affect different inflammatory biomarkers. Those with worse cognition may benefit more from skills related to regulating thought than those with better cognition.

High Heart Rate Variability Buffers the Effect of Attachment Insecurity on Sleep Quality

OBJECTIVE

Sleep quality is an important health-protective factor. Psychosocial factors, including attachment orientation, may be valuable for understanding who is at risk of poor sleep quality and associated adverse health outcomes. High attachment anxiety is reliably associated with adverse health outcomes, whereas high attachment avoidance is associated with adverse health outcomes when co-occurring with poor self-regulatory capacity, indexed by heart rate variability (HRV). We examined the associations between attachment anxiety, attachment avoidance, HRV, and sleep quality.

METHODS

Using longitudinal data from a sample of 171 older adults measured four times over 1 year ( M = 66.18 years old; 67.83% women), we separated the between-person variance (which we call "trait") and within-person variance (which we call "state") for attachment anxiety, attachment avoidance, and HRV (via the root mean square of successive differences). Sleep quality was measured with the Pittsburgh Sleep Quality Index.

RESULTS

Higher trait attachment anxiety was associated with poorer global sleep quality ( B = 0.22, p = .005). Higher state attachment avoidance was associated with poorer sleep quality ( B = -0.13, p = .01), except for those with higher trait HRV. Higher state attachment anxiety was associated with poorer sleep quality ( B = -0.15, p = .002), except for those with higher or mean trait HRV. Higher trait attachment anxiety was associated with poorer sleep quality ( B = -0.31, p = .02), except for those with higher trait HRV.

CONCLUSIONS

High trait HRV mitigated the adverse effects of attachment insecurity on sleep quality. Our results suggest that people with high trait HRV had greater self-regulation capacity, which may enable them to enact emotion regulation strategies effectively.

Children's empathy moderates the association between perceived interparental conflict and child health

Interparental conflict is known to negatively impact child well-being, including behavioral and physiological well-being. Children's empathy - that is, vicariously experiencing others' emotions - may increase children's sensitivity to and the biological repercussions of interparental conflict. Although empathy represents a valued trait and is an important part of socioemotional development, its influence on children's physical health is unknown. This study examined whether empathy moderates the association between perceived interparental conflict and both child systemic inflammation and parent-rated overall child health in a sample of children between the ages of seven to nine. Children and their parents participating in the long-term evaluation of the Family Foundations program, a randomized trial of a perinatal preventative intervention, provided data approximately eight years following enrollment into the program. We collected peripheral blood samples via dried blood spots, anthropometric measurements, and child and parent psychosocial questionnaires. Results indicated significant positive main effects of child empathy on both C-reactive protein (CRP; B = 0.26, SE = 0.11, p =.026) and Interleukin-6 (IL-6; B = 0.20, SE = 0.10, p =.045) levels. Further, child affective empathy moderated the associations between perceived interparental conflict and both CRP (B = 0.39, SE = 0.19, p =.050) and parent-reported child health (B = 0.30, SE = 0.13, p =.021), such that greater empathy strengthened the negative associations between interparental conflict and child health. Overall, findings suggests that there may be a biological cost of being more empathic in high-conflict environments and highlight the need for tools to help more empathic children appropriately manage vicarious emotions.

Discrimination and Cardiovascular Health in Black Americans: Exploring Inflammation as a Mechanism and Perceived Control as a Protective Factor

OBJECTIVE

Inflammation may be an integral physiological mechanism through which discrimination impacts cardiovascular health and contributes to racial health disparities. Limited research has examined psychosocial factors that protect against the negative effects of discrimination on inflammation. Perceived control is a promising possible protective factor, given that it has been shown to moderate the relationship between other psychosocial stressors and physiological outcomes. This study thus tested whether systemic inflammation mediated the link between discrimination and cardiovascular health and whether perceived control moderated this relationship.

METHODS

Data for this project included 347 non-Hispanic/Latinx Black adults (mean [standard deviation] age = 51.64 [11.24] years; 33% female) taken from the Midlife in the United States study. Perceived control and daily discrimination were assessed via self-report, and inflammation was measured via circulating levels of C-reactive protein (CRP), interleukin-6 (IL-6), fibrinogen, and tumor necrosis factor α. Cardiovascular health was measured by morbidity of cardiovascular conditions: heart disease, hypertension, and/or stroke.

RESULTS

CRP (indirect effect: b = 0.004, 95% confidence interval [CI] = 0.001-0.007) and fibrinogen (indirect effect: b = 0.002, 95% CI = 0.0003-0.005) mediated the link between discrimination and cardiovascular conditions. Perceived control moderated the relationship between discrimination and CRP ( F (1, 293) = 4.58, Δ R2 = 0.013, b = -0.02, SE = 0.01, p = .033). CRP mediated the link between discrimination and cardiovascular conditions only for those who reported low levels of perceived control (Index = -0.003, 95% CI = -0.007 to -0.0001).

CONCLUSION

Findings provide empirical evidence of inflammation as a mechanism linking discrimination to cardiovascular conditions among Black Americans. Additionally, perceived control may be protective. Findings could suggest beliefs about control as a potential intervention target to help reduce the negative effects of discrimination on cardiovascular health among Black Americans.

Discrimination and Cognition in Midlife Black Women: The Roles of Social Support and Spirituality

OBJECTIVES

Black women are at high risk for discrimination and cognitive impairment in late life. It is not known if discrimination is a risk factor for cognitive decline in Black women and if so, what factors are protective against the adverse cognitive effects of discrimination. Using the biopsychosocial model of gendered racism, we determined if discrimination is associated with poorer cognition in midlife Black women and if social support and/or spirituality would protect against the deleterious effects of discrimination on cognition.

METHODS

Participants were midlife Black women (N = 669) from the Study of Women's Health Across the Nation. Discrimination was measured by the Everyday Discrimination scale. Cognitive outcomes included episodic memory, processing speed, and working memory. Total social support, emotional support, instrumental support, and spirituality were assessed as protective factors.

RESULTS

Contrary to expectations, structural equation modeling indicated that discrimination was associated with better immediate recall. For women with more emotional support, greater discrimination was associated with better immediate recall than for women with lower emotional support. Spirituality was not a significant moderator in the association between discrimination and cognition.

DISCUSSION

Discrimination had unexpected positive associations with learning and attention-based cognitive skills for midlife Black women. Discrimination might enhance vigilance, which could be facilitated by higher levels of emotional support. There is an opportunity for clinical and public health interventions for cognitive health and discrimination focused on Black women to better incorporate emotional support as a coping resource.

Exposure to parental depression in adolescence and proinflammatory phenotypes 20 years later

Although the biological embedding model of adversity proposes that stressful experiences in childhood create a durable proinflammatory phenotype in immune cells, research to date has relied on study designs that limit our ability to make conclusions about whether the phenotype is long-lasting. The present study leverages an ongoing 20-year investigation of African American youth to test research questions about the extent to which stressors measured in childhood forecast a proinflammatory phenotype in adulthood, as indicated by exaggerated cytokine responses to bacterial stimuli, monocyte insensitivity to inhibitory signals from hydrocortisone, and low-grade inflammation. Parents reported on their depressive symptoms and unsupportive parenting tendencies across youths' adolescence. At age 31, youth participants (now adults) completed a fasting blood draw. Samples were incubated with lipopolysaccharide and doses of hydrocortisone to evaluate proinflammatory processes. Additionally, blood samples were tested for indicators of low-grade inflammation, including IL-6, IL-8, IL-10, and TNF-α, and soluble urokinase plasminogen activator receptor. Analyses revealed that parental depression across youths' adolescence prospectively predicted indicators of proinflammatory phenotypes at age 31. Follow-up analyses suggested that unsupportive parenting mediated these associations. These findings suggest that exposure to parental depression in adolescence leaves an imprint on inflammatory activity that can be observed 20 years later.

Heightened neural activity and functional connectivity responses to social rejection in female adolescents at risk for depression: Testing the Social Signal Transduction Theory of Depression

BACKGROUND

Although social rejection is among the strongest proximal precipitants of major depressive disorder (MDD), little is known about the underlying neurobiological mechanisms and whether neural sensitivity to social rejection may help explain differences in MDD risk. To address this issue, we tested whether neural responses to social threat differed in female adolescents at high vs. low maternal risk for MDD.

METHOD

Female adolescents with (high-risk; n = 22, Mage = 14.68) and without (low-risk; n = 30, Mage = 15.07) a maternal history of depression were experimentally exposed to negative and neutral social evaluation while undergoing an fMRI scan. Neural responses were assessed by event-related activity and functional connectivity, as well as multivoxel pattern analysis. Activity and functional connectivity analyses focused on a priori-selected regions of interest implicated in self-referential processing and emotion regulation.

RESULTS

Compared to low-risk female adolescents, high-risk female adolescents exhibited greater increases in self-reported depression and social disconnection following social evaluation. Moreover, compared to low-risk female adolescents, high-risk female adolescents exhibited greater amygdala responses to negative social evaluation and a differential pattern of functional connectivity in brain regions related to emotion regulation, self-referential processing, and negative affect. Additionally, these markers of neural threat reactivity were related to depressive symptoms.

LIMITATIONS

A cross-sectional study design and relatively small, Western sample.

CONCLUSIONS

These results suggest that exaggerated neural reactivity to social threat-and an atypical pattern of related functional connectivity-is evident in individuals with a preclinical risk factor for depression. Targeting such responding may thus be a fruitful strategy for preventing depression in at-risk youth.

Networks of C-reactive protein and depression symptoms in patients with stable coronary heart disease: Findings from the Heart and Soul Study

OBJECTIVE

Research addressing the associations between C-reactive protein (CRP) and depression among patients with stable coronary heart disease (CHD) has produced inconsistent results. This might be attributable to varying associations of CRP with specific depression symptom profiles. We responded to this challenge using various network analysis techniques.

METHODS

A total of 967 outpatients with documented CHD were drawn from the baseline cross-sectional data of the Heart and Soul Study. We first estimated mixed graphical models that included CRP and individual depression symptoms, before and after adjusting for relevant covariates, to explore whether CRP is correlated with specific facets of depression. We also investigated whether CRP levels moderated the associations between specific depression symptoms using moderated network models. Finally, we performed a network comparison test and compared the symptom network properties between non-elevated and elevated CRP groups.

RESULTS

In the network model without covariates, CRP was positively associated with fatigue, appetite changes, and psychomotor problems. CRP maintained its negative association with concentration difficulty regardless of covariate adjustment. Few symptom-symptom associations, especially those involving appetite changes, were moderated by CRP. Further, the elevated CRP group showed greater overall symptom connectivity as compared to the non-elevated group.

CONCLUSION

This study segues into CRP-depression relationship with sophisticated methodology.

Disturbance of sleep maintenance, but not sleep duration, activates nuclear factor-κB and signal transducer and activator of transcription family proteins in older adults: sex differences

STUDY OBJECTIVES

Disturbances of sleep maintenance and sleep duration are common in older adults and associated with an increased risk for age-related mortality and morbidity. Converging evidence implicates inflammation as an underlying mechanism, especially in females. However, it is unknown what specific aspects of sleep disturbance impact inflammatory mechanisms in older adults.

METHODS

Using data from community-dwelling older adults who participated in the Sleep Health and Aging Research (SHARE) field study (n = 262, mean age 71.9 ± 8.0 years), we conducted a secondary analysis to examine whether disturbance of sleep maintenance (i.e. greater amount of wake time after sleep onset [WASO]) and sleep duration (i.e. shorter total sleep time [TST]) assessed by sleep diary and actigraphy are associated with greater activation of nuclear factor (NF)-κB and signal transducer and activator of transcription (STAT) family proteins STAT1, STAT3, and STAT5 in peripheral blood monocytic cells. In addition, moderation effects of sex were explored.

RESULTS

Data were available for sleep diary (n = 82), actigraphy (n = 74), and inflammatory signaling and transcriptional measures (n = 132). As assessed by sleep diary, greater amount of WASO (β = 0.39, p < 0.01), but not TST, was associated with higher levels of NF-κB. Whereas diary-assessed sleep measures were not associated with STAT family proteins, a moderation analysis revealed that greater diary-assessed WASO was associated with higher levels of STAT1 (p < 0.05), STAT3 (p < 0.05), and STAT5 (p < 0.01) in females, but not in males. Actigraphy-assessed sleep measures were not associated either with NF-κB or STAT activation.

CONCLUSIONS

In older adults, self-reported disturbance of sleep maintenance assessed by sleep diary was uniquely associated with higher levels of NF-κB, along with higher levels of STAT family proteins in females, but not in males. Our data suggest that improvingself-reported sleep maintenance might mitigate age-related increases in inflammatory signaling and transcriptional pathways, possibly more strongly in females, with the potential to reduce mortality risk in older adults.

Associations between socioeconomic status and stroke in American adults: A population-based study

Stroke is an acute cerebrovascular disease that can lead to disability and death. This study aimed to investigate the relationship between socioeconomic status (SES) and stroke. SES was evaluated by two variables: poverty to income ratio (PIR) and education level. In this multi-subject study, we collected data from the National Health and Nutrition Examination Survey (NHANES) database between 2009 and 2018, and finally 22,792 adults (≥20 years old) were included in the study. We proceeded with weighted multivariate logistic regression analysis as well as subgroup analysis. When analyzing the effect of PIR on stroke alone, the results showed that an increase in PIR levels was associated with a decrease in stroke incidence (OR = 0.764 95% CI: (0.711, 0.820), p < 0.001). The multivariate analysis presented a decline in stroke incidence in the highest quartile PIR group compared to the lowest quartile PIR group (OR = 0.296 95% CI: (0.214, 0.409), P＜0.001). Our results indicated that PIR is a protective factor for stroke, but there are exceptions in this relationship among different people. Hence, it is imperative that policymakers, healthcare providers, and clinicians take into account the inequality distribution of SES among adults while developing and executing stroke prevention and treatment strategies.

Incorporating causal inference perspectives into psychoneuroimmunology: A simulation study highlighting concerns about controlling for adiposity in immunopsychiatry

Psychoneuroimmunology and immunopsychiatry are quickly approaching a critical point where the clinical translatability of their evidence base will be tested. To maximize chances for translational success, we believe researchers must adopt causal inference techniques that augment the causal relevance of estimates given theorized causal structures. To illustrate the utility of incorporating causal inference perspectives into psychoneuroimmunology, we applied directed acyclic graphs and a combination of empirical and simulated data to demonstrate the consequences of controlling for adiposity when testing the association between inflammation and depression under the plausible causal structure of increases in adipose tissue leading to greater inflammation that in turn promotes depression. Effect size estimates were pulled from a dataset combining the Midlife in the United States 2 (MIDUS-2) and MIDUS Refresher datasets. Data were extracted and used to simulate data reflecting an adiposity → inflammation → depression causal structure. Next, a Monte Carlo simulation study with 1,000 iterations and three sample size scenarios (Ns = 100, 250, and 500) was conducted testing whether controlling for adiposity when estimating the relation between inflammation and depression influenced the precision of this estimate. Across all simulation scenarios, controlling for adiposity reduced precision of the inflammation → depression estimate, suggesting that researchers primarily interested in quantifying inflammation → depression associations should not control for adiposity. This work thus underscores the importance of incorporating causal inference approaches into psychoneuroimmunological research.

Racial and Educational Disparities in Cumulative Exposure to Hardships of the 2008 Great Recession and Inflammation

OBJECTIVE

This cross-sectional analysis examined self-reported economic hardships of the 2008 Great Recession, race/ethnicity, educational attainment, and psychological well-being (PWB) as predictors of systemic inflammatory physiology at midlife. We also tested for differential vulnerability in the relationship between recession hardship and inflammatory physiology by race/ethnicity, education, and PWB.

METHODS

Adults from the Midlife in the United States Refresher sample completed a survey and biomedical assessments after the recession ( n = 592 non-Hispanic White respondents, n = 158 Black/African American respondents, n = 108 respondents with other race/ethnicity). Cumulative recession hardship was the sum of financial, housing, and employment-related events. Outcomes included circulating levels of interleukin 6 and C-reactive protein. General linear regression models tested main effects interactions between primary predictor variables.

RESULTS

Educational attainment was inversely associated with recession hardships ( b = -0.18, 95% confidence interval = -0.26 to -0.11, p < .001). Black/African American respondents reported more recession hardships than White respondents ( b = 1.17, 95% confidence interval = 0.67 to 1.68, p < .001). More recession hardships predicted higher levels of interleukin 6 ( b = 0.06, p < .001) and C-reactive protein ( b = 0.04, p = .004). Analyses did not support race/ethnicity, education, and PWB as moderators of the association between recession hardship and inflammatory markers.

CONCLUSIONS

Race/ethnicity and education independently predicted disparities in cumulative recession hardship exposure. Recession hardship predicted higher blood levels of inflammatory proteins associated with long-term health. The lack of findings for differential vulnerability in the relationship between recession hardship and inflammatory markers by race/ethnicity, education, or PWB was possibly due to the limited sample size.

Network analysis of inflammation and symptoms in recent onset schizophrenia and the influence of minocycline during a clinical trial

Attempts to delineate an immune subtype of schizophrenia have not yet led to the clear identification of potential treatment targets. An unbiased informatic approach at the level of individual immune cytokines and symptoms may reveal organisational structures underlying heterogeneity in schizophrenia, and potential for future therapies. The aim was to determine the network and relative influence of pro- and anti-inflammatory cytokines on depressive, positive, and negative symptoms. We further aimed to determine the effect of exposure to minocycline or placebo for 6 months on cytokine-symptom network connectivity and structure. Network analysis was applied to baseline and 6-month data from the large multi-center BeneMin trial of minocycline (N = 207) in schizophrenia. Pro-inflammatory cytokines IL-6, TNF-α, and IFN-γ had the greatest influence in the inflammatory network and were associated with depressive symptoms and suspiciousness at baseline. At 6 months, the placebo group network connectivity was 57% stronger than the minocycline group, due to significantly greater influence of TNF-α, early wakening, and pathological guilt. IL-6 and its downstream impact on TNF-α, and IFN-γ, could offer novel targets for treatment if offered at the relevant phenotypic profile including those with depression. Future targeted experimental studies of immune-based therapies are now needed.

Association between platelet to lymphocyte ratio and depression and symptom severity among adults in the United States: A cross-sectional study

Background

The pathogenesis of depression has not yet been fully understood. The association between platelet to lymphocyte ratio (PLR) and depression has been investigated in previous studies, however, the results were controversial. The objective of the study was to explore the potential relationship between PLR and depression and symptom severity.

Methods

A cross-sectional study was conducted based on the National Health and Nutrition Examination Survey (NHANES) data from 2005 to 2018. Totally 30,032 adults were analyzed, and 2480 reported depression. Depression and symptom severity were assessed with the Patient Health Questionnaire (PHQ-9). PLR was calculated as the ratio of platelets to lymphocytes. Multivariable weighted-logistic regression models and generalized additive model (GAM) were employed to evaluate the linear and nonlinear association between PLR and depression and symptom severity.

Results

There was a negative association for Q3 (odds ratio [OR]: 0.82, 95% confidence interval [CI]: 0.68 to 0.99) when comparing participants for Q1 between 10-PLR and depression after fully adjusting the covariates; however, there was no significant association between 10-PLR and symptom severity. GAM showed that 10-PLR was associated with depression and symptom severity in a nonlinear manner. The inflection points were at 12.15. Subgroup analyses showed nonlinear relationships only in specific subgroups. Conclusions: PLR is associated with depression among adults in the United States. U-shaped nonlinear relationships and threshold effects were observed between 10-PLR and depression and symptom severity. Additionally, inflammatory mechanisms vary in different sociodemographic subgroups.

Exploring the multiverse: the impact of researchers' analytic decisions on relationships between depression and inflammatory markers

In recent years, a replication crisis in psychiatry has led to a growing focus on the impact of researchers' analytic decisions on the results from studies. Multiverse analyses involve examining results across a wide array of possible analytic decisions (e.g., log-transforming variables, number of covariates, or treatment of outliers) and identifying if study results are robust to researchers' analytic decisions. Studies have begun to use multiverse analysis for well-studied relationships that have some heterogeneity in results/conclusions across studies.We examine the well-studied relationship between peripheral inflammatory markers (PIMs; e.g., white blood cell count (WBC) and C-reactive protein (CRP)) and depression severity in the large NHANES dataset (n = 25,962). Specification curve analyses tested the impact of 9 common analytic decisions (comprising of 58,000+ possible combinations) on the association of PIMs and depression severity. Relationships of PIMs and total depression severity are robust to analytic decisions (based on tests of inference jointly examining effect sizes and p-values). However, moderate/large differences are noted in effect sizes based on analytic decisions and the majority of analyses do not result in significant findings, with the percentage of analyses with statistically significant results being 46.1% for WBC and 43.8% for CRP. For associations of PIMs with specific symptoms of depression, some associations (e.g., sleep, appetite) in males (but not females) were robust to analytic decisions. We discuss how multiverse analyses can be used to guide research and also the need for authors, reviewers, and editors to incorporate multiverse analyses to enhance replicability of research findings.

C-Reactive protein and cognition: Mediation analyses with brain morphology in the UK Biobank

Cognitive impairments and abnormal immune activity are both associated with various clinical disorders. The association between C-Reactive protein (CRP), a marker associated with inflammation, and cognitive performance remains unclear. Further, mechanisms potentially linking CRP to cognition are not yet established. Brain structure may well mediate this relationship: immune processes play crucial roles in shaping and maintaining brain structure, with brain structure and function driving cognition. The United Kingdom Biobank (UKBB) is a large cohort study with extensive assessments, including high-sensitivity serum CRP levels, brain imaging, and various cognitive tasks. With data from 39,200 UKBB participants, we aimed first to determine the relationship between CRP and cognitive performance, and second, to assess metrics of brain morphology as potential mediators in this relationship. Participants were aged 40 to 70 at initial assessment and were mostly Caucasian. After accounting for potential covariates (e.g., age, sex, medical diagnoses, use of selective-serotonin reuptake inhibitors), we found CRP levels to have small, negative associations with fluid intelligence (b = -0.03, 95%CI[-0.05,-0.02], t(14381) = -3.62, p_cor = .004), and numeric memory (b = -0.03, 95%CI[-0.05,-0.01], t(14366) = -3.31, p_cor = .007). We found no evidence of brain morphology mediating these relationships (all |ab| < 0.001, all p_cor > .55). Our findings from this large sample suggest that serum-assessed CRP is of marginal importance for cognitive performance in mid-to-late aged Caucasians; the small effect sizes of statistically significant associations provide context to previous inconsistent results. The seeming lack of involvement of brain morphology suggests that other brain metrics (e.g., connectivity, functional activation) may be more pertinent to this relationship. Future work should also consider CRP levels measured in the central nervous system and/or other cytokines that may better predict cognitive performance in this population.

The roles of inflammation, affect, and interoception in predicting social perception

"Sickness behavior" is an orchestrated suite of symptoms that commonly occur in the context of inflammation, and is characterized by changes in affect, social experience, and behavior. However, recent evidence suggests that inflammation may not always produce the same set of sickness behavior (e.g., fatigue, anhedonia, and social withdrawal). Rather, inflammation may be linked with different behavior across contexts and/or across individuals, though research in this area is under-developed to-date. In the present study (n = 30), we evaluated the influence of affective context and individual differences in difficulty detecting bodily sensations (i.e., interoceptive difficulty) on social perception following an inflammatory challenge. Inflammation was induced using the influenza vaccine and inflammatory reactivity was operationalized as changes in circulating levels of interleukin-6 (IL-6) before the vaccine and approximately 24 h later. Twenty-four hours after administration of the influenza vaccine, we manipulated affective context using a well-validated affect misattribution task in which participants made trustworthiness judgments of individuals with neutral facial expressions following the rapid presentation of "prime" images that were positive or negative in affective content. Interoceptive difficulty was measured at baseline using a validated self-report measure. Results revealed significant interactions between inflammatory reactivity to the influenza vaccine and affective context on social perception. Specifically, individuals with greater inflammatory reactivity were more biased by affective context when judging the trustworthiness of neutral faces. In addition, interoceptive difficulty and affective context interacted to predict social perception such that individuals with greater interoceptive difficulty were more biased by affective context in these judgments. In sum, we provide some of the first evidence that inflammation may amplify the saliency of affective cues during social decision making. Our findings also replicate prior work linking interoceptive ability to the use of affect-as-information during social perception, but in the novel context of inflammation.

Associations between plasma inflammatory markers and psychotic disorder, depressive disorder and generalised anxiety disorder in early adulthood: A nested case-control study

BACKGROUND

Low-grade inflammation may occur in association with several mental disorders of early adulthood, though associations with markers of chronic inflammation such as soluble urokinase plasminogen activator receptor (suPAR) are less well-established. We aimed to examine associations between acute and chronic inflammatory markers and mental disorders, as well as psychiatric co-morbidity, in young adults aged 24 years in the Avon Longitudinal Study of Parents and Children.

METHODS

Included were 781 participants (of 4019 who attended at age 24 years) who completed psychiatric assessments and provided plasma samples. Of these, 377 met criteria for psychotic disorder, depressive disorder or generalised anxiety disorder and 404 did not. Plasma concentrations of IFN-γ, IL-6, IL-8, IL-10, TNF-α, CRP, sVCAM1, sICAM1, suPAR and alpha-2-macroglobulin were measured using immunoassays. Logistic regression compared standardised inflammatory marker levels in cases and controls. Negative binomial regression evaluated associations between inflammatory markers and co-morbidity (number of mental disorders). Models were adjusted for sex, body mass index, cigarette smoking, cannabis use and employment status, then additionally for childhood trauma.

RESULTS

For psychotic disorder, there was evidence for associations with IL-6 (odds ratio[OR] 1.68, 95 %CI 1.20-2.34) and suPAR (OR 1.74, 95 %CI 1.17-2.58). There was weaker evidence for an association between suPAR and depressive disorder (OR 1.31, 95 %CI 1.05-1.62). There was little evidence for associations between inflammatory markers and generalised anxiety disorder. There was weak evidence for an association between suPAR and co-morbidity (β 0.10, 95 %CI 0.01-0.19). There was little evidence for additional confounding by childhood trauma.

CONCLUSIONS

There was evidence that 24-year-olds with psychotic disorder had raised plasma IL-6 and suPAR concentrations compared to controls. These findings have implications regarding the role of inflammation in mental disorders in early adulthood.

Association of systemic inflammation with posttraumatic stress disorder after a myocardial infarction

Background

Adverse mental health conditions including depression, posttraumatic stress disorder (PTSD), and anxiety are prevalent among patients who survive myocardial infarctions (MI) and are associated with adverse outcomes. The mechanisms underlying these associations, however, are not well understood. Inflammatory pathways may mediate the cardiovascular outcomes of patients with mental health disorders. We examined the bidirectional association between PTSD symptoms and inflammatory biomarkers in a young/middle-aged post MI population. We further examined how this association may differ between women and men as well as between Black and non-Black individuals.

Methods

Participants included individuals with early onset MI between the ages 25 and 60. Mental health scores for depression, PTSD, perceived stress, and anxiety as well as inflammatory biomarkers, interleukin-6 (IL-6) and high sensitivity C-reactive protein (hsCRP), were collected at baseline and at six-month follow up. We examined the bidirectional changes in mental health symptoms and inflammatory biomarkers between baseline and follow-up.

Results

Among 244 patients in the study (mean age: 50.8, 48.4% female, 64.3% Black), the geometric means for IL-6 level and hsCRP at rest were 1.7 pg/mL and 2.76 mg/L, respectively. Mental health scores at baseline did not consistently predict changes in inflammatory biomarkers at follow-up. However, baseline levels of both IL-6 and hsCRP were robustly associated with an increase in re-experiencing PTSD symptoms at 6 months: in adjusted linear mixed models, there was a 1.58-point increase in re-experiencing PTSD symptoms per unit of baseline hsCRP (p = 0.01) and 2.59-point increase per unit of baseline IL-6 (p = 0.02). Once the analysis was stratified by race, the association was only noted in Black individuals. Baseline inflammation was not associated with change in any of the other mental health symptom scores.

Conclusion

Markers of inflammation are associated with an increase in post-event PTSD symptoms in younger or middle-aged patients who experienced an MI, especially Black patients. These results suggest a mechanistic link between inflammation and the development of PTSD among individuals with cardiovascular disease.

Relationships among Inflammatory Biomarkers and Self-Reported Treatment-Related Symptoms in Patients Treated with Chemotherapy for Gynecologic Cancer: A Controlled Comparison

Previous research suggests that inflammation triggers cancer-treatment-related symptoms (i.e., fatigue, depression, and disruptions in sleep and physical activity), but evidence is mixed. This study examined relationships between inflammatory biomarkers and symptoms in patients with gynecologic cancer compared to age-matched women with no cancer history (i.e., controls). Patients (n = 121) completed assessments before chemotherapy cycles 1, 3, and 6, and 6 and 12 months later. Controls (n = 105) completed assessments at similar timepoints. Changes in inflammation and symptomatology were evaluated using random-effects mixed models, and cross-sectional differences between patients and controls in inflammatory biomarkers and symptoms were evaluated using least squares means. Associations among inflammatory biomarkers and symptoms were evaluated using random-effects fluctuation mixed models. The results indicated that compared to controls, patients typically have higher inflammatory biomarkers (i.e., TNF-alpha, TNFR1, TNFR2, CRP, IL-1ra) and worse fatigue, depression, and sleep (ps < 0.05). Patients reported lower levels of baseline physical activity (p = 0.02) that became more similar to controls over time. Significant associations were observed between CRP, depression, and physical activity (ps < 0.05), but not between inflammation and other symptoms. The results suggest that inflammation may not play a significant role in fatigue or sleep disturbance among gynecologic cancer patients but may contribute to depression and physical inactivity.

Trauma History Predicts Decoupling of C-Reactive Protein and Somatic Symptoms: Results From a Cohort Study of Sexual and Gender Minority Youth

OBJECTIVE

Systemic inflammation can induce somatic symptoms (e.g., pain, nausea, fatigue) through neuroimmune signaling pathways. Previous research suggests that early-life adversity amplifies signaling between peripheral inflammation and the brain. We therefore hypothesized that greater lifetime trauma exposure at baseline would predict stronger associations between systemic inflammation and somatic symptoms at 2.5-year follow-up in a cohort study of sexual and gender minority youth assigned male at birth ( n = 694).

METHODS

We measured prior trauma exposure (lifetime count of traumatic event types reported at baseline), somatic symptoms (Brief Symptom Inventory somatization score), and systemic inflammation (C-reactive protein, interleukin 6, interleukin 1β, and tumor necrosis factor α). All models included age, gender, education, recent trauma exposure, substance use, body mass index, and HIV status as covariates.

RESULTS

Higher C-reactive protein concentrations were associated with greater somatic symptoms in the main effects model ( β = 0.019, 95% confidence interval [CI] = 0.006 to 0.031). Contrary to our hypothesis, we observed a negative interaction between prior trauma exposure and C-reactive protein levels in predicting somatic symptoms ( β = -0.017, 95% CI = -0.030 to -0.004). Higher C-reactive protein was associated with greater somatic symptoms only in participants without prior trauma exposure at baseline ( β = 0.044, 95% CI = 0.026 to 0.062). Specificity analyses revealed similar patterns when nonsomatic depressive symptoms were used as the outcome variable.

CONCLUSIONS

These results suggest that sexual and gender minority youth assigned male at birth who have a history of prior trauma exposure may experience decoupling of systemic inflammation and somatic symptoms. The absence of inflammation-related symptoms may prevent individuals from seeking necessary medical care by reducing interoceptive awareness of pathological states.

Support-Giving Is Associated With Lower Systemic Inflammation

BACKGROUND

Support-giving has emerged as a health-relevant social behavior, such that giving more support is associated with better physical health. However, biological mechanisms by which support-giving and health are linked remain unclear. Whether support-giving uniquely relates to health relative to other psychosocial factors is also an open research question.

PURPOSE

Two studies test the hypothesis that support-giving is uniquely (over-and-above other psychosocial factors) related to lower systemic inflammation, a biological correlate of health.

METHODS

Cross-sectional associations of support-giving with markers of systemic inflammation (i.e., interleukin-6 [IL-6], C-reactive protein [CRP]) were examined in two independent samples of midlife adults (Study 1, n = 746; Study 2, n = 350).

RESULTS

Consistent with hypotheses, giving to more social targets (to family and friends, and also volunteering for various causes), but not receiving support from similar targets, was associated with lower IL-6. In conceptual replication and extension with a different measure of support-giving, higher frequency of support-giving behavior was associated with lower IL-6, even after adjusting for social network size and individual differences in social desirability. There were no associations between support-giving and CRP in either sample.

CONCLUSIONS

Future research needs to establish causality and directly test mechanistic pathways, but together, findings reaffirm the health-relevance of support-giving behavior and shed light on a promising biological mechanism by which such effects may occur.

The role of sleep and heart rate variability in metabolic syndrome: evidence from the Midlife in the United States study

STUDY OBJECTIVES

Poor sleep and autonomic dysregulation can both disrupt metabolic processes. This study examined the individual and combined effects of poor sleep and reduced heart rate variability (HRV) on metabolic syndrome among 966 participants in the Midlife in the United States II (MIDUS II) study.

METHODS

Self-reported sleep was assessed using the Pittsburgh Sleep Quality Index (PSQI). HRV was acquired from 11-minute resting heart rate recordings. Spearman correlations, general linear regression, and logistic regression models were used to examine the study hypotheses.

RESULTS

Poor sleep quality was associated with metabolic syndrome when global PSQI scores were evaluated as a continuous (odds ratio [OR]: 1.07, 95% confidence interval [CI]: 1.03 to 1.11) or categorical measure (cutoff > 5, OR: 1.58, 95% CI: 1.19 to 2.10), after adjustment for confounding. There also was an association between reduced HRV and metabolic syndrome (ln [HF-HRV] OR: 0.89, 95% CI: 0.80 to 0.99; ln [LF-HRV] OR: 0.82, 95% CI: 0.72 to 0.92; ln [SDRR] OR: 0.59, 95% CI: 0.43 to 0.79; ln [RMSSD] OR: 0.75, 95% CI: 0.60 to 0.94). When the combined effects of poor sleep and low HRV were examined, the association with metabolic syndrome was further strengthened relative to those with normal sleep and HRV.

CONCLUSIONS

To the best of the author's knowledge, this is the first study to suggest a combined effect of poor sleep and low HRV on the odds of metabolic syndrome.

Association between inflammation and cognition: Triangulation of evidence using a population-based cohort and Mendelian randomization analyses

BACKGROUND

Inflammation is associated with cognitive functioning and dementia in older adults, but whether inflammation is related to cognitive functioning in youth and whether these associations are causal remains unclear.

METHODS

In a population-based cohort (Avon Longitudinal Study of Parents and Children; ALSPAC), we investigated cross-sectional associations of inflammatory markers (C-reactive protein [CRP], Interleukin-6 [IL-6] and Glycoprotein acetyls [GlycA]) with measures of cold (working memory, response inhibition) and hot (emotion recognition) cognition at age 24 (N = 3,305 in multiple imputation models). Furthermore, we conducted one-sample and two-sample bidirectional Mendelian randomization (MR) analyses to examine potential causal effects of genetically-proxied inflammatory markers (CRP, GlycA, IL-6, IL-6 receptor, soluble IL-6 receptor) on cognitive measures (above) and on general cognitive ability.

RESULTS

In the ALSPAC cohort, there was limited evidence of an association between standardised inflammatory markers and standardised cognitive measures at age 24 after adjusting for potential confounders (N = 3,305; beta range, -0.02 [95 % confidence interval (CI) -0.06 to 0.02, p = 0.27] to 0.02 [95 % CI -0.02 to 0.05, p = 0.33]). Similarly, we found limited evidence of potential effects of 1-unit increase in genetically-proxied inflammatory markers on standardised working memory, emotion recognition or response inhibition in one-sample MR using ALSPAC data (beta range, -0.73 [95 % CI -2.47 to 1.01, p = 0.41] to 0.21 [95 % CI -1.42 to 1.84, p = 0.80]; or on standardised general cognitive ability in two-sample MR using the latest Genome-Wide Association Study (GWAS) datasets (inverse-variance weighted beta range, -0.02 [95 % CI -0.05 to 0.01, p = 0.12] to 0.03 [95 % CI -0.01 to 0.07, p = 0.19]).

CONCLUSIONS

Our MR findings do not provide strong evidence of a potential causal effect of inflammatory markers (CRP, IL-6, IL-6 receptor, GlycA) on the cognitive functions examined here. Given the large confidence intervals in the one-sample MR, larger GWAS of specific cognitive measures are needed to enable well-powered MR analyses to investigate whether inflammation causally influences specific cognitive domains.

Participation in an Attachment-Based Home Visiting Program Is Associated with Lower Child Salivary C-Reactive Protein Levels at Follow-Up

OBJECTIVE

Exposure to early childhood adversity is associated with an increased risk for physiological disruption, including increased inflammation. Early interventions that support the mother-child relationship have been shown to potentially buffer negative psychosocial outcomes related to early adversity, but it is unclear whether these interventions have long-term biological effects. We evaluated whether prior participation in Minding the Baby® (MTB), an attachment-based home visiting intervention for young mother-infant dyads living in underserved communities, is associated with lower child salivary inflammatory biomarkers compared with controls at follow-up.

METHODS

Ninety-seven maternal-child dyads (n = 43 intervention and n = 54 controls) enrolled in a follow-up study of the MTB randomized controlled trial, an average of 4.6 years after RCT completion. Children provided salivary specimens. We used adjusted linear regression to examine the relationship between MTB participation and child salivary inflammatory biomarkers (C-reactive protein [CRP], interleukin [IL]-1β, IL-6, IL-8, and TNF-α).

RESULTS

Children were on average 6.6 years old, 48% female, and identified as non-Hispanic/Latino Black/African American (34%) and Hispanic/Latino (63%). Participation in MTB was associated with lower salivary CRP levels (β = -0.31, SE = 0.28, p = 0.003) compared with controls. Participation in MTB was not associated with salivary cytokine levels.

DISCUSSION

Participation in an intensive two-generation home visiting intervention such as MTB may reduce salivary inflammatory biomarkers associated with early childhood adversity. Replication and further research are needed to improve the understanding of the potential for early childhood interventions to buffer the biological embedding of early adversity.

Employment and family income in psychological and immune outcomes during bereavement

Spousal bereavement is one of the most stressful experiences in adulthood. In a sample of 183 widow(er)s, bereaved about three months prior, we examined the intersection of employment, family income, and health outcomes (proinflammatory marker production, perceived stress, and grief symptoms). Bereaved employees had higher levels of monocyte-stimulated interleukin-6, tumor necrosis factor-α, chemokine ligands 4, and perceived stress than bereaved retirees. We also found an interaction such that family income was positively associated with perceived stress and grief symptoms for employed window(er)s, but not for retirees. These findings align with the reserve capacity model, which states that people at higher levels of socioeconomic status have more psychosocial resources to address psychosocial stressors. Employment likely served as an added psychological and inflammatory burden for all bereaved workers, except those with the highest incomes.

Neutrophil gelatinase-associated lipocalin (NGAL) and tumor necrosis factor-α (TNF-α) levels in patients with schizophrenia

RATIONALE

Although the immune system is thought to contribute to the etiology of schizophrenia, the mechanism has not been elucidated. Clarifying the relationship between them is important in terms of diagnosis, treatment, and prevention approaches.

OBJECTIVE

In this study, it is aimed to determine whether there is any difference in serum levels of neutrophil gelatinase-associated lipocalin (NGAL) and tumor necrosis factor-alpha (TNF-α) in the group of patients with schizophrenia and healthy volunteers, whether these values are changed by medical treatment, whether there is any relation between these values and the severity of the symptoms of patients with schizophrenia, and whether NGAL can be used as a biomarker in the diagnosis and the follow-up of the schizophrenia.

METHODS

A total of 64 patients who were hospitalized in the Psychiatry Clinic of Ankara City Hospital and diagnosed with schizophrenia and 55 healthy volunteers were included in the study. A sociodemographic information form was given to all participants and TNF-α and NGAL values were measured. Positive and Negative Symptoms Rating Scale (PANSS) were applied to the schizophrenia group on admission and follow-up. TNF-α and NGAL levels were re-measured in the 4th week after the start of antipsychotic treatment.

RESULTS

As a result of the present study, it was found that NGAL levels decreased significantly after antipsychotic treatment of schizophrenia patients hospitalized with exacerbation. There was no significant correlation between NGAL and TNF-α levels among schizophrenia and the control group.

CONCLUSION

In psychiatric diseases, especially schizophrenia, there may be differences in immune and inflammatory markers compared to the healthy population. After treatment, the NGAL levels of the patients at follow-up were reduced compared to the levels at admission. It can be thought that NGAL may be related to psychopathology in schizophrenia and antipsychotic treatment. This is the first follow-up study for NGAL levels in schizophrenia.

Mean affect and affect variability may interact to predict inflammation

INTRODUCTION

Individuals with greater affect variability (i.e., moment-to-moment fluctuations possibly reflecting emotional dysregulation) are at risk for greater systemic inflammation, which is associated with cardiovascular disease. Some evidence suggests that affect variability is linked with poorer health indicators only among those with higher average levels of affect, particularly for positive affect (PA), and that associations may be non-linear. The present study sought to examine whether links between both PA and negative affect (NA) variability and inflammation are moderated by average level of affect.

METHODS

Participants (N = 300, 50 % female, ages 21-70, 60 % non-Hispanic White, 19 % Hispanic, 15 % non-Hispanic Black) completed a lab assessment and provided a blood sample to measure systemic inflammation (i.e., TNF-α, IL-6, CRP). Affect was collected via a two-day ecological momentary assessment protocol where reports were collected about every 45-min during waking hours. Momentary affect ratings were averaged across both days (i.e., iM), separately for PA and NA, for each participant. Affect variability was calculated as the person-specific SD (i.e., iSD) of affect reports, separately for PA and NA. Linear and quadratic interactions were tested. Models included covariates for sex, race, and body mass index.

RESULTS

There were significant interactions between NA iM and NA iSD predicting TNF-α (b = 6.54; p < 0.05) and between PA iM and PA iSD predicting IL-6 (b = 0.45; p < 0.05). Specifically, the association between these affect variability indicators and inflammatory markers were suggestive of a positive association among those with higher average affect but a negative association among those with lower average affect. There was no evidence of non-linear associations between affect and inflammation.

DISCUSSION

Incorporating interactive effects between affect variability and average affect may be an important consideration in understanding affective-inflammatory associations.

The role of early life adversity and inflammation in stress-induced change in reward and risk processes among adolescents

BACKGROUND

Early life adversity (ELA) has long been associated with increased risk for stress-related psychopathology, particularly depression. The neuroimmune network hypothesis posits that ELA increases sensitivity to psychosocial stress, moderating the association between increases in peripheral markers of inflammation and decreases in reward outcomes linked to anhedonia and risk-taking behaviors. The present study examined this hypothesis in a sample of adolescents by using acute psychosocial stress to probe the role of inflammatory signaling in behavioral measures of reward and risk processing.

METHOD

80 adolescents [13.86 years (SD = 1.54); 45 % female], oversampled for ELA, underwent the Trier Social Stress Test for Children while providing blood samples immediately before and 60-minutes after stress onset. Blood samples were assayed for plasma IL-6. One hour before stress onset, and then 60 min after, participants completed computer-administered behavioral tasks measuring reward (Pirate Task) and risk (Balloon Analog Risk Task).

RESULTS

ELA moderated the association between increases in IL-6 and decreases in risk tolerance in pursuit of rewards (p = 0.003) and reward response bias (p = 0.04). Stress-induced increases in IL-6 were associated with decreases in pumps for rewards among adolescents exposed to high, relative to little or no, ELA. Further, greater IL-6 increases were associated with increases in bias toward high relative to low value rewards among adolescents with low adversity exposure but not among those exposed to higher adversity.

CONCLUSIONS

The present study provides the first evidence in a pediatric sample that ELA may alter the role of stress-induced inflammation in reward and risk processing, and may extend our understanding of why stress leads to depression in this high-risk population.

Sleep and Healthy Aging Research on Depression (SHARE-D) randomized controlled trial: Protocol overview of an experimental model of depression with insomnia, inflammation, and affect mechanisms in older adults

Depression, one of the most common diseases in older adults, carries significant risk for morbidity and mortality. Because of the burgeoning population of older adults, the enormous burden of late-life depression, and the limited efficacy of current antidepressants in older adults, biologically plausible models that translate into selective depression prevention strategies are needed. Insomnia predicts depression recurrence and is a modifiable target to prevent incident and recurrent depression in older adults. Yet, it is not known how insomnia gets converted into biological- and affective risk for depression, which is critical for identification of molecular targets for pharmacologic interventions, and for refinement of insomnia treatments that target affective responding to improve efficacy. Sleep disturbance activates inflammatory signaling and primes immune responses to subsequent inflammatory challenge. In turn, inflammatory challenge induces depressive symptoms, which correlate with activation of brain regions implicated in depression. This study hypothesizes that insomnia serves as a vulnerability factor for inflammation-related depression; older adults with insomnia will show heightened inflammatory- and affective responding to inflammatory challenge as compared to those without insomnia. To test this hypothesis, this protocol paper describes a placebo-controlled, randomized, double-blind study of low dose endotoxin in older adults (n = 160; 60-80 y) with insomnia vs. comparison controls without insomnia. The aims of this study are to examine differences in depressive symptoms, measures of negative affective responding, and measures of positive affective responding as a function of insomnia and inflammatory challenge. If the hypotheses are confirmed, older adults with two "hits", insomnia and inflammatory activation, would represent a high risk group to be prioritized for monitoring and for depression prevention efforts using treatments that target insomnia or inflammation. Moreover, this study will inform the development of mechanism-based treatments that target affect responses in addition to sleep behaviors, and which might also be coupled with efforts to reduce inflammation to optimize efficacy of depression prevention.

Inflammatory and Oxidative Stress Biomarkers in the Elderly, the Birjand Longitudinal Aging Study

Cigarette smoking is a significant risk factor for chronic and atherosclerotic vascular disease that causes preventable considerable morbidity and mortality worldwide. This study is aimed at comparing inflammation and the levels of oxidative stress biomarkers in elderly subjects. The authors recruited the participants (1281 older adults) from the Birjand Longitudinal of Aging study. They measured oxidative stress and inflammatory biomarkers serum levels in the 101 cigarettes and 1180 nonsmokers. The mean age of smokers was 69.3 ± 7.95 years, and most were male. The most percentage of male cigarette smokers have lower body mass index (BMI) (≤19 kg/m²). Females have higher BMI categories than males (P ≤ 0.001). The percentage of diseases and defects was different between cigarette and non-cigarette smoker adults (P ≤ 0.01 to P ≤ 0.001). The total white blood cells, neutrophils, and eosinophils were significantly higher in cigarettes compared to non-cigarette smokers (P ≤ 0.001). Besides, cigarette consumers' percentage of hemoglobin and hematocrit compared to other aged people was significantly different (P ≤ 0.001). However, biomarkers of oxidative stress and antioxidant levels were not significant differences between the two senior groups. Cigarette smoking in older adults was associated with increased inflammatory biomarkers and cells, but it did not find a significant difference in oxidative stress markers. Longitudinal prospective studies may help illuminate the mechanisms inducing oxidative stress and inflammation due to cigarette smoking in each gender.

Exploring Associations between C-Reactive Protein and Self-Reported Interoception in Major Depressive Disorder: A Bayesian Analysis

Major depressive disorder (MDD) is associated with dysfunctional self-reported interoception (i.e., abnormal perception of the body's physiological state) and systemic inflammation, both of which adversely affect treatment response. In this study, we explored associations between C-reactive protein (CRP) and self-reported interoception, to gain more insight into the pathophysiology of interoceptive impairments in MDD. We also aimed to replicate previous findings on the associations of depression and fatigue severity with CRP. The study included 97 depressed individuals, who completed self-administered questionnaires (Multidimensional Assessment of Interoceptive Awareness (MAIA-2); Beck Depression Inventory-II, Multidimensional Fatigue Inventory). CRP concentrations were analyzed in the serum using a particle-enhanced turbidimetric immunoassay. We applied Bayesian inference to estimate robust effect parameters from posterior distributions based on MCMC sampling, and computed Bayes factors (BF₁₀) as indices of relative evidence. The bivariate analysis supported evidence against associations between CRP and self-reported interoception (BF₁₀ ≤ 0.32), except for one dimension (Not-Distracting: r = 0.11, BF₁₀ > 0.43, absence of evidence). Positive correlations with overall depression (r = 0.21, BF₁₀ = 3.19), physical fatigue (r = 0.28, BF₁₀ = 20.64), and reduced activity (r = 0.22, BF₁₀ = 4.67) were found. The multivariate analysis showed moderate evidence that low-grade inflammation predicted higher scores on the MAIA-2 Not-Worrying scale (β = 0.28, BF₁₀ = 3.97), after controlling for relevant confounders. Inflammatory responses, as measured by CRP, may not be involved in the pathophysiology of dysfunctional self-reported interoception. However, systemic low-grade inflammation could potentially exert a protective effect against worries about pain or discomfort sensations. An immunological involvement in interoceptive impairments cannot be ruled out until future studies considering additional biomarkers of inflammation replicate our findings.

Hierarchical Inflammatory Phenotypes of Depression: A Novel Approach Across Five Independent Samples and 27,730 Adults

BACKGROUND

Although characterizing associations between inflammation and depression may prove critical for informing theory, research, and treatment decisions, extant research has been limited by ignoring the possibility that inflammation may be simultaneously associated with depression broadly and with a subset of symptoms. This lack of direct comparison has hampered attempts to understand inflammatory phenotypes of depression and critically fails to consider that inflammation might be uniquely associated with both depression broadly and individual symptoms.

METHODS

We used moderated nonlinear factor analysis in 5 NHANES (National Health and Nutrition Examination Survey) cohorts (N = 27,730, 51% female, mean age = 46 years).

RESULTS

C-reactive protein (CRP) is simultaneously associated with latent depression, appetite, and fatigue. Specifically, CRP was associated with latent depression in all 5 samples (rs: 0.044-0.089; ps: < .001-.002) and was associated with both appetite (significant rs: 0.031-0.049, significant ps: .001-.007) and fatigue (significant rs: 0.030-0.054, significant ps: < .001-.029) in 4 samples. These results were largely robust to covariates.

CONCLUSIONS

Methodologically, these models indicate that the Patient Health Questionnaire-9 is scalar noninvariant as a function of CRP (i.e., identical Patient Health Questionnaire-9 scores may represent different constructs in those with high vs. low CRP levels). Therefore, mean comparisons of depression total scores and CRP might be misleading without accounting for symptom-specific associations. Conceptually, these findings indicate that studies investigating inflammatory phenotypes of depression should examine how inflammation is simultaneously related both to depression broadly and to specific symptoms, and whether these relations function via different mechanisms. This has the potential to yield new theoretical insights and may lead to the development of novel therapies for reducing inflammation-related symptoms of depression.

The Link Between Positive and Negative Parenting Behaviors and Child Inflammation: A Systematic Review

Children's inflammation may be an important link between parenting behaviors and health outcomes. The aims of this systematic review were to: (1) describe associations between parenting behaviors and child inflammatory markers, and (2) evaluate the relevance of existing literature to the review question. Database searches identified 19 studies that included a measure of positive or negative parenting behaviors and a marker of child inflammation, 53% of which measured parental responsiveness/warmth. Greater parental responsiveness/warmth was associated with lower levels of child pro-inflammatory markers in 60% of studies. Across studies, the association between parenting and child inflammation varied as a function of parenting construct, inflammatory measure, and sample characteristics. Studies were highly relevant, with 42% rated 5 + out of 6 for study's ability to address links between parenting behavior and child inflammation. If future research uncovers causal effects of parenting behaviors on inflammation, parenting interventions could be employed as a preventative tool.

Intergenerational transmission of lifetime stressor exposure in adolescent girls at differential maternal risk for depression

OBJECTIVE

Adolescent girls who grow up with mothers who are depressed are themselves highly vulnerable to developing depression (i.e., "intergenerational transmission of depression"). Stressor exposure is a strong risk factor for depression, and the transmission of depression risk from mothers to daughters is partly due to mothers experiencing more stressors, increasing daughters' stressor burden. However, research in this area has only assessed recent stressors, making the role of cumulative lifetime stressors unclear.

METHOD

To address this issue, we recruited 52 dyads of mothers and adolescent daughters, of which 22 daughters were at high maternal risk for depression. Participants completed diagnostic interviews, and daughters additionally self-reported their depressive symptoms. Participants also completed the Stress and Adversity Inventory, a new-generation instrument for assessing cumulative lifetime history of acute and chronic stressors based on the contextual threat approach. We tested moderated mediation models evaluating the conditional indirect effects of mothers' lifetime stressors on high- versus low-risk daughters' depressive symptoms through daughters' lifetime stressors.

RESULTS

As hypothesized, mothers of high-risk (but not low-risk) adolescent daughters who reported more lifetime acute stressors had daughters who reported more lifetime acute stressors and current depressive symptoms. Moreover, this finding was driven specifically by mothers' stressors occurring after their daughters' births. There was also tentative evidence that high-risk daughters' lifetime chronic stressors potentiated the impact of daughters' acute stressors on their depressive symptoms.

CONCLUSION

These findings provide new insights into how stressful contexts are transmitted intergenerationally.

Improving biobehavioral health in younger breast cancer survivors: Pathways to Wellness trial secondary outcomes

BACKGROUND

The Pathways to Wellness trial tested the efficacy of 2 interventions for younger breast cancer survivors: mindful awareness practices (MAPs) and survivorship education (SE). This planned secondary analysis examines intervention effects on stress, positive psychological outcomes, and inflammation (Clincaltrials.gov NCT03025139).

METHODS

Women diagnosed with breast cancer at or before age 50 years who had completed treatment and had elevated depressive symptoms were randomly assigned to 6 weeks of MAPs, SE, or wait-list control (WLC). Assessments conducted at pre- and postintervention and at 3- and 6-month follow-up measured general stress perceptions, cancer-related intrusive thoughts and worry, positive affect, meaning and peace in life, altruism and empathy, and markers of inflammation. Analyses compared change in outcomes over time in each intervention group relative to WLC using linear mixed models.

RESULTS

A total 247 women were randomly assigned to MAPs (n = 85), SE (n = 81), or WLC (n = 81). MAPs statistically significantly decreased intrusive thoughts and worry at postintervention and 3-month follow-up relative to WLC (P < .027) and statistically significantly increased positive affect and meaning and peace at postintervention, with positive affect persisting at 3-month follow-up (P < .027). SE statistically significantly decreased intrusive thoughts at 3-month follow-up and statistically significantly increased positive affect at 6-month follow-up relative to WLC (P < .01). Proinflammatory gene expression increased in WLC relative to MAPs (P = .016) but did not differ from SE. There were no intervention effects on other outcomes.

CONCLUSION

MAPs had beneficial effects on psychological and immune outcomes in younger breast cancer survivors and is a promising approach for enhancing biobehavioral health.

C-Reactive Protein and Specific Depression Symptoms Among Older Adults: An Exploratory Investigation of Multi-Plane Networks Using Cross-Sectional Data From NHANES (2017-2020)

INTRODUCTION

Studies investigating the association between C-reactive protein (CRP) and depression among older adults have yielded inconsistent results. We suspect that this may be due to varying associations between CRP and particular depression symptom criteria, and we addressed this challenge using network analysis.

METHODS

We used cross-sectional data from prepandemic National Health and Nutrition Examination Survey questionnaires (2017-2020) and included a sample of 1698 adults aged 65 years or older. Depression symptoms were assessed using the Patient Health Questionnaire-9. Unregularized Mixed Graphical Models were estimated using the R package mgm before and after adjusting for relevant sociodemographic, clinical, and lifestyle covariates.

RESULTS

In the model with no covariates, the only symptom criterion associated with CRP was "appetite problems." This association remained robust after controlling for all covariates. Although not associated with CRP, other criteria such as "fatigue" and "concentration difficulty" showed associations with important covariates for older adults such as white blood cell count or hemoglobin, respectively.

DISCUSSION

The CRP-related variability in the depression symptom network that we have demonstrated may help explain the reported inconsistencies. The present study stands as exploratory, and future research should focus on applying longitudinal designs and including several other inflammatory proteins and covariates that were not measured in the current network model.

Everyday co-presence with a romantic partner is associated with lower C-reactive protein

Social relationships are an important driver of health, and inflammation has been proposed as a key neurobiological mechanism to explain this effect. Behavioral researchers have focused on social relationship quality to further explain the association, yet recent research indicates that relationship quality may not be as robust a predictor as previously thought. Here, building on animal models of social bonds and recent theory on close relationships, we instead investigated merely being in the physical presence of one's romantic partner. Specifically, we tested the hypothesis that spending more time co-present with a loved partner in everyday life would be associated with lower C-reactive protein (CRP). Three times over the course of one month, 100 people in romantic relationships reported how much time they spent in the same physical space as their partner in the prior 24 h, in minutes, and provided a sample of blood for CRP assay (n observations = 296). Results from multi-level models showed that when one reported spending more time in the physical presence of their partner they had lower CRP - an effect that was independent from social relationship quality explanations from the prior literature, including romantic relationship quality, hostility, and loneliness. These findings move past global assessments of social isolation to consider a novel everyday behavior that is of great interest in the non-human animal literature - spending time together -- as a potential mechanism linking high-quality relationships and physical health in adult humans. The findings also point to future research on additional behavioral mechanisms that are not dependent on stress pathways: people in high-quality relationships tend to spend enjoyable and affectionate time with one another, which may impact inflammation.

Chronic Home Radon Exposure Is Associated with Higher Inflammatory Biomarker Concentrations in Children and Adolescents

Children are particularly vulnerable to the deleterious impacts of toxic environmental exposures, though the effects of some rather ubiquitous toxins have yet to be characterized in youths. One such toxin, radon gas, is known to accumulate to hazardous levels in homes, and has been linked with the incidence of lung cancer in aging adults. However, the degree to which chronic home radon exposure may impact risk for health problems earlier in life is unknown. Herein, we explored the degree to which chronic home radon exposure relates to biomarkers of low-grade inflammation in 68 youths ages 6- to 14 years old residing in an area of the United States prone to high home radon concentrations. Parents completed a home radon test kit, and youths provided a saliva sample to assess concentrations of five biomarkers. Using a multiple regression approach, we found that greater radon exposure was specifically associated with higher levels of C-reactive protein (β = 0.31, p = 0.007) and interleukin-1β (β = 0.33, p = 0.016). The data suggested specificity in associations between chronic home radon exposure and different biomarkers of inflammatory activity and highlight a pathway which may confer risk for future mental and physical health maladies.

Racial/ethnic variations in inflammatory markers: exploring the role of sleep duration and sleep efficiency

Individuals from minoritized racial/ethnic groups have higher levels of circulating inflammatory markers. However, the mechanisms underlying these differences remain understudied. The objective of this study was to examine racial/ethnic variations in multiple markers of inflammation and whether impaired sleep contributes to these racial/ethnic differences. Nurses from two regional hospitals in Texas (n = 377; 71.62% White; 6.90% Black; 11.14% Hispanic, 10.34% Asian; mean age = 39.46; 91.78% female) completed seven days of sleep diaries and actigraphy to assess mean and variability in total sleep time (TST) and sleep efficiency (SE). On day 7, blood was drawn to assess 4 inflammatory markers: C-reactive protein (CRP), Interleukin-6 (IL-6), Interleukin-1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α). Results from regression models showed differences in inflammatory markers by race/ethnicity, adjusting for age and gender. The associations between sleep parameters and inflammatory markers also varied by race/ethnicity. Among White nurses, lower mean and greater variability in actigraphy-determined TST and greater variability in diary-determined TST were associated with higher levels of IL-6. Among Black nurses, lower mean diary-determined SE was associated with higher levels of IL-6 and IL-1β. Among Hispanic nurses, greater diary-determined mean TST was associated with higher CRP. Among Asian nurses, greater intraindividual variability in actigraphy-determined SE was associated with lower CRP. Among nurses, we did not find racial/ethnic disparities in levels of inflammation. However, analyses revealed differential relationships between sleep and inflammatory markers by race/ethnicity. Results highlight the importance of using a within-group approach to understand predictors of inflammatory markers.

Pulmonary exacerbation inflammatory phenotypes in adults with cystic fibrosis

BACKGROUND

Adults with cystic fibrosis (CF) develop exuberant inflammatory responses during pulmonary exacerbations (PEx) but whether distinct systemic inflammatory profiles can be identified and whether these associate with disparate treatment outcomes are unclear. We conducted a pilot study to address this question and hypothesized that CF adults with a pauci-inflammatory phenotype might derive less clinical benefit from intravenous (IV) antibiotic treatment than patients with other systemic inflammatory phenotypes.

METHODS

Six proteins reflective of systemic inflammation were examined in 37 PEx from 28 unique CF subjects. We applied exploratory factor analysis and cluster analysis to identify biological clusters. Levels of blood proteins at PEx and clinical outcomes following IV antibiotic treatment were compared between clusters.

RESULTS

Three clusters of PEx were identified. The pauci-inflammatory phenotype was characterized by lower levels of interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, calprotectin, and C-reactive protein (CRP) (p < 0.05). Higher levels of IL-6 and IL-1β were observed in the other 2 inflammatory clusters, but one of them was associated with higher calprotectin levels (p = 0.001) (neutrophil-predominant phenotype); whereas the other was associated with increased TNF-α and IL-10 levels (p < 0.001) (pro-inflammatory phenotype). A greater proportion of events from the neutrophil-predominant phenotype presented with acute respiratory symptoms and a larger decrease in ppFEV₁ from baseline to hospital admission than the other two inflammatory phenotypes (p = 0.03).

CONCLUSIONS

Three distinct inflammatory phenotypes were identified at PEx admission and each presented with unique clinical characteristics.

Validation of a novel method of ultraviolet-induced cutaneous inflammation and its associations with anhedonia

Affective immunology of the skin is a growing area; however, established protocols for measuring individual differences in cutaneous inflammation are lacking. To address this, we present a preliminary validation of Precision Implementation of Minimal Erythema Dose (PI-MED) testing as a method for measuring cutaneous inflammation. PI-MED is a recently adapted protocol, optimized for reproducibility and individual differences research, that uses ultraviolet (UV) light to evoke cutaneous erythema, or inflammatory skin reddening. PI-MED's novel UV dosage schedule produces standardized erythema responses across different skin pigmentation types and shows strong internal consistency within person and good test-retest reliability across 8-10 weeks. In line with predictions, increased PI-MED erythema was associated with heightened anhedonia, across several measures, beyond influences of non-affective covariates. While future work should further refine the dosage schedule for the lightest and darkest skin types, overall, evidence supports PI-MED as a protocol for inducing and measuring individual differences in cutaneous inflammation. Further, PI-MED-induced erythema can expand psychoneuroimmunology research by offering a complementary assessment for general inflammatory tone. This work adds to a growing body of evidence demonstrating a distinct relationship between inflammation and anhedonia.