Altered cellular immune reactivity in traumatized women with and without major depressive disorder

Social determinants of inflammatory markers linking depression and type 2 diabetes among women: A scoping review

OBJECTIVE

Inflammation is implicated in the pathophysiology of depression and type 2 diabetes (T2D) and is linked to social determinants of health (SDoH) associated with socioeconomic disadvantage. The objective of this review is to identify and map the range of SDoHs associated with inflammation in depression, T2D, or their co-occurrence among women.

METHODS

PubMed, CINAHL, PsychINFO, and Web of Science were searched March-July 2023 to identify studies where 1) an SDoH was a predictor or independent variable, 2) depression or T2D was a clinical focus, 3) inflammatory markers were collected, and 4) analysis was specific to women. We used the National Institute on Minority Health and Health Disparities research framework to guide searching SDoHs, organize findings, and identify gaps.

RESULTS

Of the 1135 studies retrieved, 46 met criteria. Within the reviewed studies, the most used inflammatory measures were C-reactive protein, interleukin-6, and tumor necrosis factor-α, and the most studied SDoHs were early life stress and socioeconomic status. Individual and interpersonal-level variables comprised the bulk of SDoHs in the included studies, while few to no studies examined built environment (n = 6) or health system level (n = 0) factors. Disadvantageous SDoHs were associated with higher levels of inflammation across the included studies.

CONCLUSION

The scope and intersection of depression and T2D represent a syndemic that contributes to and results from socioeconomic inequities and disproportionately affects women. Simultaneous inclusion of social and inflammatory measures, particularly understudied SDoHs, is needed to clarify potent targets aimed at advancing health and equity.

Adipokines in depressed women with and without adverse childhood experiences

BACKGROUND

Adverse childhood experiences (ACE) elevate the risk of both major depressive disorder (MDD) and metabolic diseases. The underlying pathophysiology might include alterations of adipokine levels as a consequence of ACE. In this study, we used a full-factorial design to investigate the levels of select adipokines in women with ACE-only (n = 23), MDD-only (n = 27), ACE+MDD (n = 25) and healthy controls (HC, n = 29) to identify metabolic makers associated with vulnerability and resilience of developing MDD after ACE exposure.

METHODS

Serum levels of adiponectin, leptin, adiponectin-to-leptin (A/L) ratio, and retinol binding protein 4 (RBP4) were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Adiponectin levels did not differ between groups. Individuals with vs. without MDD showed higher leptin serum concentrations. As predicted, A/L ratio indicated lower values in individuals with vs. without ACE. RBP4 showed a more nuanced pattern with reduced levels in the ACE-only and MDD-only groups compared to HC. Furthermore, the ACE-only group showed lower RBP4 concentrations compared to ACE+MDD. These results were not accounted by BMI or medication status.

CONCLUSION

Our results do not support the utility of adiponectin and leptin as predictors of vulnerability or resilience of developing MDD after ACE. In contrast, RBP4 might play a role in resilience towards the development of MDD following ACE. Further research on this more recently discovered adipokine seems warranted.

Network analysis of plasma proteomes in affective disorders

The conventional differentiation of affective disorders into major depressive disorder (MDD) and bipolar disorder (BD) has insufficient biological evidence. Utilizing multiple proteins quantified in plasma may provide critical insight into these limitations. In this study, the plasma proteomes of 299 patients with MDD or BD (aged 19-65 years old) were quantified using multiple reaction monitoring. Based on 420 protein expression levels, a weighted correlation network analysis was performed. Significant clinical traits with protein modules were determined using correlation analysis. Top hub proteins were determined using intermodular connectivity, and significant functional pathways were identified. Weighted correlation network analysis revealed six protein modules. The eigenprotein of a protein module with 68 proteins, including complement components as hub proteins, was associated with the total Childhood Trauma Questionnaire score (r = -0.15, p = 0.009). Another eigenprotein of a protein module of 100 proteins, including apolipoproteins as hub proteins, was associated with the overeating item of the Symptom Checklist-90-Revised (r = 0.16, p = 0.006). Functional analysis revealed immune responses and lipid metabolism as significant pathways for each module, respectively. No significant protein module was associated with the differentiation between MDD and BD. In conclusion, childhood trauma and overeating symptoms were significantly associated with plasma protein networks and should be considered important endophenotypes in affective disorders.

Retinoid homeostasis in major depressive disorder

The small, hormone-like molecule retinoic acid (RA) is a vital regulator in several neurobiological processes that are affected in depression. Next to its involvement in dopaminergic signal transduction, neuroinflammation, and neuroendocrine regulation, recent studies highlight the role of RA in homeostatic synaptic plasticity and its link to neuropsychiatric disorders. Furthermore, experimental studies and epidemiological evidence point to the dysregulation of retinoid homeostasis in depression. Based on this evidence, the present study investigated the putative link between retinoid homeostasis and depression in a cohort of 109 patients with major depressive disorder (MDD) and healthy controls. Retinoid homeostasis was defined by several parameters. Serum concentrations of the biologically most active Vitamin A metabolite, all-trans RA (at-RA), and its precursor retinol (ROL) were quantified and the individual in vitro at-RA synthesis and degradation activity was assessed in microsomes of peripheral blood-derived mononuclear cells (PBMC). Additionally, the mRNA expression of enzymes relevant to retinoid signaling, transport, and metabolism were assessed. Patients with MDD had significantly higher ROL serum levels and greater at-RA synthesis activity than healthy controls providing evidence of altered retinoid homeostasis in MDD. Furthermore, MDD-associated alterations in retinoid homeostasis differed between men and women. This study is the first to investigate peripheral retinoid homeostasis in a well-matched cohort of MDD patients and healthy controls, complementing a wealth of preclinical and epidemiological findings that point to a central role of the retinoid system in depression.

Ex vivo LPS-stimulated cytokine production is associated with cortisol curves in response to acute psychosocial stress

BACKGROUND

Empirical and theoretical evidence suggest that because of the co-evolution of the endocrine and immune response systems, different types of stressors may lead to similar levels of physiological activation. The present analyses examined associations between two physiological stress responses: the cortisol response to an acute laboratory stressor and ex vivo lipopolysaccharide (LPS) stimulated inflammatory cytokine production.

METHODS

Healthy middle-aged adults (N = 65) completed testing at two appointments, two weeks apart. Blood was collected at each appointment to measure circulating inflammatory cytokine levels and stimulated inflammatory cytokine production after 4 and 24 hours of incubation with LPS. A cumulative standardized composite measure of inflammation was calculated using the cytokines interleukin-6 (IL-6), interleukin-1β (IL-1β), and interferon-γ (IFN-γ). At visit two, after the blood draw, participants completed the Trier Social Stress Test (TSST); saliva samples were collected before and after to generate cortisol response curves (area under the curve with respect to ground [AUC_G] and increase/decrease [AUC_I]).

RESULTS

AUC_G was significantly associated with stimulated cytokine production at visit 2 after both 4 hours (B = 6.89; p = 0.007) and 24 hours (B = 7.50; p = 0.005) of incubation, controlling for age, sex, and BMI. AUC_I was also significantly associated with stimulated cytokine production at visit 2 after 4 hours (B = 6.28; p = 0.004) and 24 hours (B = 6.16; p = 0.007) of incubation, controlling for age, sex, and BMI. Stimulated inflammatory cytokine production was strongly correlated across the two visits (2 weeks apart) after 4 hours of incubation (r = 0.80, p < 0.001) and after 24 hours (r = 0.80, p < 0.001). Within each visit, stimulated cytokine production after 4 hours was significantly correlated with stimulated inflammation at 24 hours (r = 0.93-0.94, p < 0.05) CONCLUSIONS: These results suggest that LPS-stimulated inflammatory cytokine production and the cortisol response to the TSST contain comparable information about acute human physiological stress responses. Moreover, measurement of stimulated cytokines was highly stable across a two-week time period whether measured after 4 or 24 hours of incubation with LPS.