Heritability estimates of innate immunity: an extended twin study

Molecular biomarker approaches to prevention of post-traumatic osteoarthritis

Up to 50% of individuals develop post-traumatic osteoarthritis (PTOA) within 10 years following knee-joint injuries such as anterior cruciate ligament rupture or acute meniscal tear. Lower-extremity PTOA prevalence is estimated to account for ≥12% of all symptomatic osteoarthritis (OA), or approximately 5.6 million cases in the USA. With knowledge of the inciting event, it might be possible to 'catch PTOA in the act' with sensitive imaging and soluble biomarkers and thereby prevent OA sequelae by early intervention. Existing biomarker data in the joint-injury literature can provide insights into the pathogenesis and early risk trajectory related to PTOA and can help to elucidate a research agenda for preventing or slowing the onset of PTOA. Non-traumatic OA and PTOA have many clinical, radiological and genetic similarities, and efforts to understand early risk trajectories in PTOA might therefore contribute to the identification and classification of early non-traumatic OA, which is the most prevalent form of OA.

No evidence of association between either Modic change or disc degeneration and five circulating inflammatory proteins

Introduction

Intervertebral disc degeneration and Modic change are the main spinal structural changes associated with chronic low back pain (LBP). Both conditions are thought to manifest local inflammation and if inflammatory proteins translocate to the blood circulation could be detected systemically. The work here assesses whether the presence of disc degeneration is associated with detectable blood level changes of five inflammatory markers and whether chronic LBP is associated with these changes.

Materials and Methods

Two hundred and forty TwinsUK cohort participants with both MRI disc degeneration grade and Modic change extent, and IL-6, IL-8, IL-8 TNF, and CX3CL1 protein blood concentration measurements were included in this work. Linear mixed effects models were used to test the association of blood cytokine concentration with disc degeneration score and Modic change volumetric score. Association of chronic LBP status from questionnaires with disc degeneration, Modic change, and cytokine blood concentration was also tested.

Results

No statistically significant association between disc degeneration or Modic change with cytokine blood concentration was found. Instead, regression analysis pointed strong association between cytokine blood concentration with body mass index for IL-6 and with age for IL-6 and TNF. Mild association was found between IL-8 blood concentration and body mass index. Additionally, LBP status was associated with Modic change volumetric score but not associated with any cytokine concentration.

Conclusions

We found no evidence that Modic change and disc degeneration are able to produce changes in tested blood cytokine concentration. However, age and body mass index have strong influence on cytokine concentration and both are associated with the conditions studied which may confound associations found in the literature. It is then unlikely that cytokines produced in the disc or vertebral bone marrow induce chronic LBP.

The interactive association of adverse childhood experiences and polygenic susceptibility with depressive symptoms and chronic inflammation in older adults: a prospective cohort study

BACKGROUND

Adverse childhood experiences (ACEs) and genetic liability are important risk factors for depression and inflammation. However, little is known about the gene-environment (G × E) mechanisms underlying their aetiology. For the first time, we tested the independent and interactive associations of ACEs and polygenic scores of major depressive disorder (MDD-PGS) and C-reactive protein (CRP-PGS) with longitudinal trajectories of depression and chronic inflammation in older adults.

METHODS

Data were drawn from the English longitudinal study of ageing (N~3400). Retrospective information on ACEs was collected in wave3 (2006/07). We calculated a cumulative risk score of ACEs and also assessed distinct dimensions separately. Depressive symptoms were ascertained on eight occasions, from wave1 (2002/03) to wave8 (2016/17). CRP was measured in wave2 (2004/05), wave4 (2008/09), and wave6 (2012/13). The associations of the risk factors with group-based depressive-symptom trajectories and repeated exposure to high CRP (i.e. ⩾3 mg/L) were tested using multinomial and ordinal logistic regression.

RESULTS

All types of ACEs were independently associated with high depressive-symptom trajectories (OR 1.44, 95% CI 1.30-1.60) and inflammation (OR 1.08, 95% CI 1.07-1.09). The risk of high depressive-symptom trajectories (OR 1.47, 95% CI 1.28-1.70) and inflammation (OR 1.03, 95% CI 1.01-1.04) was also higher for participants with higher MDD-PGS. G×E analyses revealed that the associations between ACEs and depressive symptoms were larger among participants with higher MDD-PGS (OR 1.13, 95% CI 1.04-1.23). ACEs were also more strongly related to inflammation in participants with higher CRP-PGS (OR 1.02, 95% CI 1.01-1.03).

CONCLUSIONS

ACEs and polygenic susceptibility were independently and interactively associated with elevated depressive symptoms and chronic inflammation, highlighting the clinical importance of assessing both ACEs and genetic risk factors to design more targeted interventions.

Predictors of Chronic Fatigue Syndrome and Mood Disturbance After Acute Infection

Prospective cohort studies following individuals from acute infections have documented a prevalent post-infective fatigue state meeting diagnostic criteria for chronic fatigue syndrome (CFS) – that is, a post-infective fatigue syndrome (PIFS). The Dubbo Infection Outcomes Study (DIOS) was a prospective cohort following individuals from acute infection with Epstein-Barr virus (EBV), Ross River virus (RRV), or Q fever through to assessment of caseness for CFS designated by physician and psychiatrist assessments at 6 months. Previous studies in DIOS have revealed that functional genetic polymorphisms in both immunological (pro- and anti-inflammatory cytokines) and neurological (the purinergic receptor, P2X7) genes are associated with both the severity of the acute infection and subsequent prolonged illness. Principal components analysis was applied to self-report data from DIOS to describe the severity and course of both the overall illness and concurrent mood disturbance. Associations between demographics and acute infection characteristics, with prolonged illness course as well as the PIFS outcome were examined using multivariable statistics. Genetic haplotype-driven functional variations in the neuropeptide Y (NPY) gene previously shown to be associated with brain responses to stress, and to trait anxiety were also examined as predictors. The sample included 484 subjects (51% female, median age 32, IQR 19–44), of whom 90 (19%) met diagnostic criteria for CFS at 6 months. Participants with greater overall illness severity and concurrent mood disturbance in the acute illness had a more prolonged illness severity (HR = 0.39, 95% CI: 0.34–0.46, p < 0.001) and mood disturbance (HR = 0.36, 95% CI: 0.30–0.42, p < 0.001), respectively. Baseline illness severity and RRV infection were associated with delayed recovery. Female gender and mood disturbance in the acute illness were associated with prolonged mood disturbance. Logistic regression showed that the odds of an individual being diagnosed with PIFS increased with greater baseline illness severity (OR = 2.24, 95% CI: 1.71–2.94, p < 0.001). There was no association between the NPY haplotypes with overall illness severity or mood disturbance either during the acute illness phase or with prolonged illness (p > 0.05). Severe acute infective illnesses predicted prolonged illness, prolonged mood disturbance and PIFS. These factors may facilitate early intervention to manage both PIFS and mood disturbances.

Human Variation in DNA Repair, Immune Function, and Cancer Risk

DNA damage constantly threatens genome integrity, and DNA repair deficiency is associated with increased cancer risk. An intuitive and widely accepted explanation for this relationship is that unrepaired DNA damage leads to carcinogenesis due to the accumulation of mutations in somatic cells. But DNA repair also plays key roles in the function of immune cells, and immunodeficiency is an important risk factor for many cancers. Thus, it is possible that emerging links between inter-individual variation in DNA repair capacity and cancer risk are driven, at least in part, by variation in immune function, but this idea is underexplored. In this review we present an overview of the current understanding of the links between cancer risk and both inter-individual variation in DNA repair capacity and inter-individual variation in immune function. We discuss factors that play a role in both types of variability, including age, lifestyle, and environmental exposures. In conclusion, we propose a research paradigm that incorporates functional studies of both genome integrity and the immune system to predict cancer risk and lay the groundwork for personalized prevention.

Twin study reveals non-heritable immune perturbations in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system underpinned by partially understood genetic risk factors and environmental triggers and their undefined interactions1,2. Here we investigated the peripheral immune signatures of 61 monozygotic twin pairs discordant for MS to dissect the influence of genetic predisposition and environmental factors. Using complementary multimodal high-throughput and high-dimensional single-cell technologies in conjunction with data-driven computational tools, we identified an inflammatory shift in a monocyte cluster of twins with MS, coupled with the emergence of a population of IL-2 hyper-responsive transitional naive helper T cells as MS-related immune alterations. By integrating data on the immune profiles of healthy monozygotic and dizygotic twin pairs, we estimated the variance in CD25 expression by helper T cells displaying a naive phenotype to be largely driven by genetic and shared early environmental influences. Nonetheless, the expanding helper T cells of twins with MS, which were also elevated in non-twin patients with MS, emerged independent of the individual genetic makeup. These cells expressed central nervous system-homing receptors, exhibited a dysregulated CD25-IL-2 axis, and their proliferative capacity positively correlated with MS severity. Together, our matched-pair analysis of the extended twin approach allowed us to discern genetically and environmentally determined features of an MS-associated immune signature.

More than just a pretty face? The relationship between immune function and perceived facial attractiveness

It has long been hypothesized that attractiveness provides a cue to a target's health and immunocompetence. However, much of the research testing this hypothesis has relied on a small number of indirect proxies of immune function, and the results of this research have been mixed. Here, we build on this past research, examining the relationship between target attractiveness and (i) self-reported health, (ii) in vivo measures of inflammation and white blood cell count/composition, and (iii) in vitro tests of targets' immune function, including (c₁) leucocyte proliferation in response to immunological stimulants, (c₂) phagocytosis of Escherichia coli bioparticles, (c₃) NK cell-mediated lysis of target tumour cells, and (c₄) Staphylococcus aureus growth in isolated plasma. Results revealed multiple, sometimes sex-differentiated, relationships between targets' immune function and others' perceptions of their attractiveness. Together, this work suggests complex, often sex-differentiated relationships between immune function, health, and attractiveness.

Quantile-Dependent Expressivity of Serum Interleukin-6 Concentrations as a Possible Explanation of Gene-Disease Interactions, Gene-Environment Interactions, and Pharmacogenetic Effects

Interleukin 6 (IL-6) is a moderately heritable pleiotropic cytokine whose elevated concentrations in coronary artery disease, peripheral arterial disease, pulmonary arterial hypertension, Eales' disease, Sjògren's syndrome, osteoarthritis, adenocarcinoma, neuroblastoma, polymyalgia rheumatica, pulmonary tuberculosis, and enterovirus 71 infection, and following coronary artery bypass graft show larger genetic effects than in unaffected low IL-6 controls. We hypothesize that genetic effects may depend upon whether average IL-6 concentrations are high or low, i.e., quantile-dependent expressivity. Quantile-specific offspring-parent (β_OP) and full-sib regression slopes (β_FS) were estimated by applying quantile regression to the age- and sex-adjusted serum IL-6 concentrations in families surveyed in the Framingham Heart Study. Quantile-specific heritabilities were calculated as h² = 2β_OP / (1 + r_spouse) and h² = {(1 + 8r_spouseβ_FS)^0.5 -1} / (2r_spouse)). Heritability (h² ± SE) of IL-6 concentrations increased from 0.01 ± 0.01 at the 10th percentile (NS), 0.02 ± 0.01 at the 25th (P = 0.009), 0.03 ± 0.01 at the 50th (P = 0.007), 0.04 ± 0.02 at the 75th (P = 0.004), and 0.13 ± 0.05 at the 90th percentile (P = 0.03), or 0.0005 ± 0.0002 for each 1% increase in the offspring's phenotype distribution (P_{linear trend} = 0.02) when estimated from β_OP and from 0.02 ± 0.02 at the 10th (NS), 0.02 ± 0.02 at the 25th (NS), 0.06 ± 0.02 at the 50th (P = 0.01), 0.12 ± 0.04 at the 75th (P = 0.001), and 0.30 ± 0.03 at the 90th percentile (P < 10^-16), or 0.0015 ± 0.0007 for each 1% increase in the sibling phenotype distribution (P_{linear trend} = 0.02) when estimated from β_FS. Thus the heritability of serum IL-6 concentrations is quantile dependent, which may contribute in part to the larger genetic effect size reported for diseases and environmental conditions that elevate IL-6 concentrations vis-à-vis unaffected controls.

Correlations of psychological distress with plasma cytokine levels and gene mutations in acral and non-acral melanoma

BACKGROUND

The presence of psychological distress has negatively affected the course and prognosis of melanoma. Psychological distress is influenced by cytokines and gene mutations, particularly in cancer, but no studies have investigated this phenomenon in melanoma patients. This study investigated the correlations of psychological distress, plasma cytokine levels, and gene mutations in melanoma patients, focusing on melanoma sites and TNM stages.

METHODS

This study prospectively evaluated melanoma patients who visited Chonnam National University Hwasun Hospital from September 2020 to March 2021. Melanoma sites were divided into acral and non-acral sites. Anxiety and depression were evaluated using the Hospital Anxiety and Depression Scale, and quality of life was evaluated with EuroQol-5 Dimensions. Plasma cytokine levels, and depression- and cytokine-related gene mutations were analyzed.

RESULTS

This study included 151 melanoma patients. Anxiety was found in 14.6% of the patients, and depression in 29.8%. The melanoma sites were not significantly associated with anxiety, depression, or quality of life. However, psychological distress was significantly associated with the plasma cytokines IL-2, IL-4, IL-5, IL-10, IL-12, TNF-α and IFN-γ. COMT, SLC6A4, SLC6A3, and IL-12b gene mutations were also associated with melanoma sites and TNM stage, anxiety, and QOL.

CONCLUSION

Psychological distress was associated with plasma cytokine levels and depression- and cytokine-related gene mutations. Using psychiatric intervention and emotional support, cytokine levels related to melanoma can be changed, which may have positive effects on the prognosis and treatment of melanoma. More careful follow-up, evaluation, and management are needed for patients with gene mutations.

Blood Cell In Vitro Cytokine Production in Response to Lipopolysaccharide Stimulation in a Healthy Population: Effects of Age, Sex, and Smoking

Immune system functionality has been commonly assessed by a whole-blood or isolated-cell stimulation assay. The aim of this study was to determine whether cytokine production in whole-blood-stimulated samples is influenced by age, sex, and smoking. A descriptive cross-sectional study in 253 healthy participants aged 18-55 years was conducted. Whole blood samples were stimulated for 24 h with LPS and concentrations of IL-6, IL-10, and TNF-α were determined in the culture media. Among parameters considered, statistical regression analysis indicated that smoking (change in R² = 0.064, p < 0.001) and sex (change in R² = 0.070, p < 0.001) were the main predictors for IL-10 production, with higher values for women and non-smokers. Age was also found to be a significant predictor (change in R² = 0.021, p < 0.001), with higher values for younger ages. Age (change in R² = 0.089, p = 0.013) and smoking (change in R² = 0.037, p = 0.002) were found to be negative predictors for IL-6 production. Regarding TNF-α-stimulated production, age (change in R² = 0.029, p = 0.009) and smoking (change in R² = 0.022, p = 0.022) were found to be negative predictors. Furthermore, sex (change in R² = 0.016, p = 0.045) was found to be a significant predictor, with lower values for women. In conclusion, sex, age, and smoking were found to be independent determinants of stimulated cytokine production. While female sex is associated with higher IL-10 and lower TNF-α production, aging and smoking are associated with lower IL-6, IL-10, and TNF-α production.

The relationship between the plasma proinflammatory cytokine levels of depressed/anxious children and their parents

Recent studies suggest immune function dysregulation in depression and anxiety disorders. Elevated pro-inflammatory cytokines may be a marker for immune system dysregulation. No study assessed the correlation between the levels of cytokines in children and adolescents with depression/anxiety disorders and their parents. In this study, 92 children and adolescents (mean age 13.90 ± 2.41 years) with depression and/or anxiety disorders were treated with fluoxetine. Blood samples were collected before initiation of treatment. One hundred and sixty-four of their parents (mean age 50.6 ± 6.2 years) and 25 parents of healthy children (mean age 38.5 ± 6.2 years) also gave blood samples. Plasma levels of three pro-inflammatory cytokine (TNF-α, IL-6, IL-1β) were measured by enzyme linked immunosorbent assays (ELISA) and compared between depressed/anxious children and their parents. We also compared cytokine levels between parents of children with depression/anxiety and control parents. Mothers of depressed children had higher TNF-α levels than mothers of controls. No significant difference was detected in the fathers. A positive correlation was found between the IL-1β levels of the depressed/anxious boys and their mothers. No such correlation was observed in the fathers. Our conclusions are that higher levels of proinflammatory cytokines may indicate immune system activation in mothers in response to the distress associated with having depressed/anxious offspring. The correlation between IL-1β levels in the mothers and their depressed/anxious children may indicate familial vulnerability to depression and anxiety. Our observation highlights the need for a better understanding of sexual dimorphism in inflammatory responses to stress.

Epigenetics of Sepsis

OBJECTIVES

Recent evidence from the fields of microbiology and immunology, as well as a small number of human sepsis studies, suggest that epigenetic regulation may play a central role in the pathogenesis of sepsis. The term "epigenetics" refers to regulatory mechanisms that control gene expression but are not related to changes in DNA sequence. These include DNA methylation, histone modifications, and regulation of transcription via non-coding RNAs. Epigenetic modifications, occurring in response to external stressors, lead to changes in gene expression, and thus lie at the intersection between genetics and the environment. In this review, we examine data from in vitro studies, animal studies, and the existing human sepsis studies in epigenetics to demonstrate that epigenetic mechanisms are likely central to the pathogenesis of sepsis and that epigenetic therapies may have potential in the treatment of sepsis and its associated organ failures.

DATA SOURCES

Online search of published scientific literature via Pubmed using the term "epigenetics" in combination with the terms "sepsis", "infection", "bacterial infection", "viral infection", "critical illness", "acute respiratory distress syndrome", and "acute lung injury".

STUDY SELECTION

Articles were chosen for inclusion based on their relevance to sepsis, acute inflammation, sepsis-related immune suppression, and sepsis-related organ failure. Reference lists were reviewed to identify additional relevant articles.

DATA EXTRACTION

Relevant data was extracted and synthesized for narrative review.

DATA SYNTHESIS

Epigenetic regulation is a key determinant of gene expression in sepsis. At the onset of infection, host-pathogen interactions often result in epigenetic alterations to host cells that favor pathogen survival. In parallel, the host inflammatory response is characterized by epigenetic modifications in key regulatory genes, including tumor necrosis factor and interleukin-1β. In human sepsis patients, multiple epigenetic modifying enzymes show differential expression in early sepsis, suggesting a role for epigenetics in coordinating the response to infection. In the later stages of sepsis, epigenetic modifications accompany endotoxin tolerance and the immune-suppressed state. In animal models, treatment with epigenetic modifiers can mitigate the effects of sepsis and improve survival as well as reverse sepsis-associated organ injury.

CONCLUSIONS

Epigenetic modifications are associated with key phases of sepsis, from the host-pathogen interaction, to acute inflammation, to immune suppression. Epigenetic markers show promise in the diagnosis and prognosis of sepsis and epigenetic modifying agents show promise as therapeutic tools in animal models of sepsis. Human studies in the area of epigenetics are sorely lacking and should be a priority for sepsis researchers.

Long-Term Ambient Air Pollution Exposures and Circulating and Stimulated Inflammatory Mediators in a Cohort of Midlife Adults

BACKGROUND

Chronic exposure to air pollution may prime the immune system to be reactive, increasing inflammatory responses to immune stimulation and providing a pathway to increased risk for inflammatory diseases, including asthma and cardiovascular disease. Although long-term exposure to ambient air pollution has been associated with increased circulating markers of inflammation, it is unknown whether it also relates to the magnitude of inflammatory response.

OBJECTIVES

The aim of this study was to examine associations between chronic ambient pollution exposures and circulating and stimulated levels of inflammatory mediators in a cohort of healthy adults.

METHODS

Circulating interleukin (IL)-6, C-reactive protein (CRP) (n=392), and lipopolysaccharide stimulated production of IL-1β, IL-6, and tumor necrosis factor (TNF)-α (n=379) were measured in the Adult Health and Behavior II cohort. Fine particulate matter [particulate matter with aerodynamic diameter less than or equal to 2.5 μm (PM2.5)] and constituents [black carbon (BC), and lead (Pb), manganese (Mn), zinc (Zn), and iron (Fe)] were estimated for each residential address using hybrid dispersion land use regression models. Associations between pollutant exposures and inflammatory measures were examined using linear regression; models were adjusted for age, sex, race, education, smoking, body mass index, and month of blood draw.

RESULTS

There were no significant correlations between circulating and stimulated measures of inflammation. Significant positive associations were found between exposure to PM2.5 and BC with stimulated production of IL-6, IL-1β, and TNF-α. Pb, Mn, Fe, and Zn exposures were positively associated with stimulated production of IL-1β and TNF-α. No pollutants were associated with circulating IL-6 or CRP levels.

DISCUSSION

Exposure to PM2.5, BC, Pb, Mn, Fe, and Zn was associated with increased production of inflammatory mediators by stimulated immune cells. In contrast, pollutant exposure was not related to circulating markers of inflammation. These results suggest that chronic exposure to some pollutants may prime immune cells to mount larger inflammatory responses, possibly contributing to increased risk for inflammatory disease. https://doi.org/10.1289/EHP7089.

EX-vivo whole blood stimulation with A2E does not elicit an inflammatory cytokine response in patients with age-related macular degeneration

Age-related macular degeneration (AMD) is a highly prevalent degenerative disease and a leading cause of vision loss worldwide. Evidence for an inflammatory component in the development of AMD exists, yet the exact mechanisms remain unclear. Bisretinoid N-retinylidene-N-retinylethanolamine (A2E) in retinal pigmental epithelial (RPE) cells, and in extracellular deposits constitutes a hallmark of AMD, but its role in the pathology of AMD is elusive. Here, we tested the hypothesis that A2E is responsible for the heightened inflammatory activity in AMD. To this end, we measured ex vivo mRNA expression of the cytokines TNF-α, IL-6, and IL-10 in whole blood samples after stimulation with A2E in a clinical sample of 27 patients with neovascular AMD and 24 patients with geographic atrophy secondary to AMD. Patients’ spouses (n = 30) were included as non-affected controls. After stimulation with A2E, no statistical differences were found in the median expression level of TNF-α, IL-6, IL-10 between the control group, and the neovascular AMD and the geographic atrophy group. Our findings do not support evidence for the hypothesis, that A2E per se contributes to heightened inflammatory activity in AMD.

Adjuvants and Vaccines Used in Allergen-Specific Immunotherapy Induce Neutrophil Extracellular Traps

Aluminum hydroxide (alum) and monophosphoryl-lipid A (MPLA) are conventional adjuvants in vaccines for allergen-specific immunotherapy (AIT). Alum triggers the release of neutrophil extracellular traps (NETs) by neutrophils. NETs contain expelled decondensed chromatin associated with granular material and may act as danger-associated molecular patterns and activate antigen-presenting cells. We investigated whether adjuvant-induced NETs contribute to innate responses to AIT-vaccines. Human neutrophils were incubated with alum, MPLA and adjuvant-containing AIT-vaccine preparations. NETs were verified by time-lapse and confocal fluorescence microscopy and quantitatively assessed by DNA and elastase release and ROS production. In contrast to MPLA, alum represented a potent trigger for NET release. Vaccine formulations containing alum resulted in less NET release than alum alone, whereas the vaccine containing MPLA induced stronger NET responses than MPLA alone. NETs and alum alone and synergistically increased the expression of molecules involved in antigen presentation, i.e., CD80, CD86 and CD83, by peripheral blood monocytes. Monocyte priming with NETs resulted in individually differing IL-1β- and IL-6-responses. Thus, NETs induced by adjuvants in AIT-vaccines can provide autonomous and cooperative effects on early innate responses. The high diversity of individual innate responses to adjuvants and AIT-vaccines may affect their therapeutic efficacy.

Circulating cytokines associated with clinical response to systemic therapy in metastatic renal cell carcinoma

Background

Circulating cytokines and angiogenic factors have been associated with clinical outcomes in patients with metastatic renal cell carcinoma (RCC) receiving systemic therapy. However, none have yet examined cytokine concentrations in parallel cohorts receiving either immunotherapy or targeted therapy.

Methods

In this prospective correlative study, we enrolled 56 patients who were planned for treatment with either a vascular endothelial growth factor-tyrosine kinase inhibitor (VEGF-TKI) or immune checkpoint inhibitor (ICI). Eligibility requirements permitted any RCC histologic subtype, International Metastatic Renal Cell Carcinoma risk classification, and line of therapy. Immunologic profile was assessed at baseline and after 1 month on treatment using a Human Cytokine 30-plex protein assay (Invitrogen). Clinical benefit was defined as complete response, partial response, or stable disease ≥6 months per RECIST (Response Evaluation Criteria in Solid Tumors) V.1.1 criteria.

Results

Clinical benefit was similar between VEGF-TKI and ICI arms (65% vs 54%). Patients with clinical benefit from VEGF-TKIs had lower pretreatment levels of interleukin-6 (IL-6) (p=0.02), IL-1RA (p=0.03), and granulocyte colony-stimulating factor (CSF) (p=0.02). At 1 month, patients with clinical benefit from ICIs had higher levels of interferon-γ (IFN-γ) (p=0.04) and IL-12 (p=0.03). Among patients on VEGF-TKIs, those with clinical benefit had lower 1 month IL-13 (p=0.02) and granulocyte macrophage CSF (p=0.01) as well as higher 1 month VEGF (p=0.04) compared with patients with no clinical benefit.

Conclusion

For patients receiving VEGF-TKI or ICI therapy, distinct plasma cytokines were associated with clinical benefit. Our findings support additional investigation into plasma cytokines as biomarkers in metastatic RCC.

Personalized Medicine Using Neuroimmunological Biomarkers in Depressive Disorders

Major depressive disorder (MDD) is associated with increased suicidal risk and reduced productivity at work. Neuroimmunology, the study of the immune system and nervous system, provides further insight into the pathogenesis and outcome of MDD. Cytokines are the main modulators of neuroimmunology, and their levels are somewhat entangled in depressive disorders as they affect depressive symptoms and are affected by antidepressant treatment. The use of cytokine-derived medication as a treatment option for MDD is currently a topic of interest. Although not very promising, cytokines are also considered as possible prognostic or diagnostic markers for depression. The machine learning approach is a powerful tool for pattern recognition and has been used in psychiatry for finding useful patterns in data that have translational meaning and can be incorporated in daily clinical practice. This review focuses on the current knowledge of neuroimmunology and depression and the possible use of machine learning to widen our understanding of the topic.

Regulation of the Acute Sickness Response by the P2RX7 Receptor

BACKGROUND

The acute sickness response to infection is a stereotyped set of illness manifestations initiated by proinflammatory signals in the periphery but mediated centrally. P2RX7 is a highly polymorphic gene encoding an ATP-gated cationic pore, widely expressed on immune cells and the brain, and regulating the NLRP3 inflammasome, as well as diverse neural functions.

METHODS

Associations between P2RX7 genotype, pore activity, and illness manifestations were examined in a cohort with acute viral and bacterial infections (n = 484). Genotyping of 12 P2RX7 function-modifying single-nucleotide polymorphisms (SNPs) was used to identify haplotypes and diplotypes. Leucocyte pore activity was measured by uptake of the fluorescent dye, YO-PRO-1, and by ATP-induced interleukin-1β (IL-1β) release. Associations were sought with scores describing the symptom domains, or endophenotypes, derived from principal components analysis.

RESULTS

Among the 12 SNPs, a 4-SNP haplotype block with 5 variants was found in 99.5% of the subjects. These haplotypes and diplotypes were closely associated with variations in pore activity and IL-1β production. Homozygous diplotypes were associated with overall illness severity as well as fatigue, pain, and mood disturbances.

CONCLUSIONS

P2RX7 signaling plays a significant role in the acute sickness response to infection, likely acting in both the immune system and the brain.

Cytokines mapping for tissue-specific expression, eQTLs and GWAS traits

Dysregulation in cytokine production has been linked to the pathogenesis of various immune-mediated traits, in which genetic variability contributes to the etiopathogenesis. GWA studies have identified many genetic variants in or near cytokine genes, nonetheless, the translation of these findings into knowledge of functional determinants of complex traits remains a fundamental challenge. In this study we aimed at collection, analysis and interpretation of data on cytokines focused on their tissue-specific expression, eQTLs and GWAS traits. Using GO annotations, we generated a list of 314 cytokines and analyzed them with the GTEx resource. Cytokines were highly tissue-specific, 82.3% of cytokines had Tau expression metrics ≥ 0.8. In total, 3077 associations for 1760 unique SNPs in or near 244 cytokines were mapped in the NHGRI-EBI GWAS Catalog. According to the Experimental Factor Ontology resource, the largest numbers of disease associations were related to 'Inflammatory disease', 'Immune system disease' and 'Asthma'. The GTEx-based analysis revealed that among GWAS SNPs, 1142 SNPs had eQTL effects and influenced expression levels of 999 eGenes, among them 178 cytokines. Several types of enrichment analysis showed that it was cytokines expression variability that fundamentally contributed to the molecular origins of considered immune-mediated conditions.

Role of inflammasomes in the pathogenesis of periodontal disease and therapeutics

Inflammasomes are a group of multimolecular intracellular complexes assembled around several innate immune proteins. Recognition of a diverse range of microbial, stress and damage signals by inflammasomes results in direct activation of caspase‐1, which subsequently induces the only known form of secretion of active interleukin‐1β and interleukin‐18. Although the importance of interleukin‐1β in the periodontium is not questioned, the impact of inflammasomes in periodontal disease and its potential for therapeutics in periodontology is still in its very early stages. Increasing evidence in preclinical models and human data strongly implicate the involvement of inflammasomes in a number of inflammatory, autoinflammatory and autoimmune disorders. Here we review: (a) the currently known inflammasome functions, (b) clinical/preclinical data supporting inflammasome involvement in the context of periodontal and comorbid diseases and (c) potential therapies targeting inflammasomes. To clarify further the inflammasome involvement in periodontitis, we present analyses of data from a large clinical study (n = 5809) that measured the gingival crevicular fluid‐interleukin‐1β and grouped the participants based on current periodontal disease classifications. We review data on 4910 European‐Americans that correlate 16 polymorphisms in the interleukin‐1B region with high gingival crevicular fluid‐interleukin‐1β levels. We show that inflammasome components are increased in diseased periodontal tissues and that the caspase‐1 inhibitor, VX‐765, inhibits ~50% of alveolar bone loss in experimental periodontitis. The literature review further supports that although patients clinically present with the same phenotype, the disease that develops probably has different underlying biological pathways. The current data indicate that inflammasomes have a role in periodontal disease pathogenesis. Understanding the contribution of different inflammasomes to disease development and distinct patient susceptibility will probably translate into improved, personalized therapies.

Age-related macular degeneration: A two-level model hypothesis

Age-related diseases, including age-related macular degeneration (AMD), are of growing importance in a world where population ageing has become a dominant global trend. Although a wide variety of risk factors for AMD have been identified, age itself remains by far the most important risk factor, making it an urgent priority to understand the connections between underlying ageing mechanisms and pathophysiology of AMD. Ageing is both multicausal and variable, so that differences between individuals in biological ageing processes are the focus of a growing number of pathophysiological studies seeking to explain how ageing contributes to chronic, age-related conditions. The aim of this review is to integrate the available knowledge on the pathophysiology of AMD within the framework of the biology of ageing. One highly significant feature of biological ageing is systemic inflammation, which arises as a second-level response to a first level of molecular damage involving oxidative stress, mutations etc. Combining these insights, the various co-existing pathophysiological explanations in AMD arrange themselves according to a two-level hypothesis. Accordingly, we describe how AMD can be considered the consequence of age-related random accumulation of molecular damage at the ocular level and the subsequent systemic inflammatory host response thereof. We summarize evidence and provide original data to enlighten where evidence is lacking. Finally, we discuss how this two-level hypothesis provides a foundation for thoughts and future studies in prevention, prognosis, and intervention.

Multivariate Genome-wide Association Analysis of a Cytokine Network Reveals Variants with Widespread Immune, Haematological, and Cardiometabolic Pleiotropy

Cytokines are essential regulatory components of the immune system, and their aberrant levels have been linked to many disease states. Despite increasing evidence that cytokines operate in concert, many of the physiological interactions between cytokines, and the shared genetic architecture that underlies them, remain unknown. Here, we aimed to identify and characterize genetic variants with pleiotropic effects on cytokines. Using three population-based cohorts (n = 9,263), we performed multivariate genome-wide association studies (GWAS) for a correlation network of 11 circulating cytokines, then combined our results in meta-analysis. We identified a total of eight loci significantly associated with the cytokine network, of which two (PDGFRB and ABO) had not been detected previously. In addition, conditional analyses revealed a further four secondary signals at three known cytokine loci. Integration, through the use of Bayesian colocalization analysis, of publicly available GWAS summary statistics with the cytokine network associations revealed shared causal variants between the eight cytokine loci and other traits; in particular, cytokine network variants at the ABO, SERPINE2, and ZFPM2 loci showed pleiotropic effects on the production of immune-related proteins, on metabolic traits such as lipoprotein and lipid levels, on blood-cell-related traits such as platelet count, and on disease traits such as coronary artery disease and type 2 diabetes.

Phytosterols Suppress Phagocytosis and Inhibit Inflammatory Mediators via ERK Pathway on LPS-Triggered Inflammatory Responses in RAW264.7 Macrophages and the Correlation with Their Structure

Phytosterols, found in many commonly consumed foods, exhibit a broad range of physiological activities including anti-inflammatory effects. In this study, the anti-inflammatory effects of ergosterol, β-sitosterol, stigmasterol, campesterol, and ergosterol acetate were investigated in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. Results showed that all phytosterol compounds alleviated the inflammatory reaction in LPS-induced macrophage models; cell phagocytosis, nitric oxide (NO) production, release of tumor necrosis factor-α (TNF-α), and expression and activity of pro-inflammatory mediator cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and phosphorylated extracellular signal-regulated protein kinase (p-ERK) were all inhibited. The anti-inflammatory activity of β-sitosterol was higher than stigmasterol and campesterol, which suggests that phytosterols without a double bond on C-22 and with ethyl on C-24 were more effective. However, inconsistent results were observed upon comparison of ergosterol and ergosterol acetate (hydroxy or ester group on C-3), which suggest that additional research is still needed to ascertain the contribution of structure to their anti-inflammatory effects.

Genome-wide association study identifies seven novel loci associating with circulating cytokines and cell adhesion molecules in Finns

BACKGROUND

Inflammatory processes contribute to the pathophysiology of multiple chronic conditions. Genetic factors play a crucial role in modulating the inflammatory load, but the exact mechanisms are incompletely understood.

OBJECTIVE

To assess genetic determinants of 16 circulating cytokines and cell adhesion molecules (inflammatory phenotypes) in Finns.

METHODS

Genome-wide associations of the inflammatory phenotypes were studied in Northern Finland Birth Cohort 1966 (N=5284). A subsequent meta-analysis was completed for 10 phenotypes available in a previous genome-wide association study, adding up to 13 577 individuals in the study. Complementary association tests were performed to study the effect of the ABO blood types on soluble adhesion molecule levels.

RESULTS

We identified seven novel and six previously reported genetic associations (p<3.1×10-9). Three loci were associated with soluble vascular cell adhesion molecule-1 (sVCAM-1) level, one of which was the ABO locus that has been previously associated with soluble E-selectin (sE-selectin) and intercellular adhesion molecule-1 (sICAM-1) levels. Our findings suggest that the blood type B associates primarily with sVCAM-1 level, while the A1 subtype shows a robust effect on sE-selectin and sICAM-1 levels. The genotypes in the ABO locus associating with higher soluble adhesion molecule levels tend to associate with lower circulating cholesterol levels and lower cardiovascular disease risk.

CONCLUSION

The present results extend the knowledge about genetic factors contributing to the inflammatory load. Our findings suggest that two distinct mechanisms contribute to the soluble adhesion molecule levels in the ABO locus and that elevated soluble adhesion molecule levels per se may not increase risk for cardiovascular disease.

Family-based analyses reveal novel genetic overlap between cytokine interleukin-8 and risk for suicide attempt

BACKGROUND

Suicide is major public health concern. It is imperative to find robust biomarkers so that at-risk individuals can be identified in a timely and reliable manner. Previous work suggests mechanistic links between increased cytokines and risk for suicide, but questions remain regarding the etiology of this association, as well as the roles of sex and BMI.

METHODS

Analyses were conducted using a randomly-ascertained extended-pedigree sample of 1882 Mexican-American individuals (60% female, mean age = 42.04, range = 18-97). Genetic correlations were calculated using a variance components approach between the cytokines TNF-α, IL-6 and IL-8, and Lifetime Suicide Attempt and Current Suicidal Ideation. The potentially confounding effects of sex and BMI were considered.

RESULTS

159 individuals endorse a Lifetime Suicide Attempt. IL-8 and IL-6 shared significant genetic overlap with risk for suicide attempt (ρg = 0.49, pFDR = 7.67 × 10-03; ρg = 0.53, pFDR = 0.01), but for IL-6 this was attenuated when BMI was included as a covariate (ρg = 0.37, se = 0.23, pFDR = 0.12). Suicide attempts were significantly more common in females (pFDR = 0.01) and the genetic overlap between IL-8 and risk for suicide attempt was significant in females (ρg = 0.56, pFDR = 0.01), but not in males (ρg = 0.44, pFDR = 0.30).

DISCUSSION

These results demonstrate that: IL-8 shares genetic influences with risk for suicide attempt; females drove this effect; and BMI should be considered when assessing the association between IL-6 and suicide. This finding represents a significant advancement in knowledge by demonstrating that cytokine alterations are not simply a secondary manifestation of suicidal behavior, but rather, the pathophysiology of suicide attempts is, at least partly, underpinned by the same biological mechanisms responsible for regulating inflammatory response.

Men Have a Stronger Monocyte-Derived Cytokine Production Response upon Stimulation with the Gram-Negative Stimulus Lipopolysaccharide than Women: A Pooled Analysis Including 15 Study Populations

The incidence of bacterial infections and sepsis, as well as the mortality risk from sepsis, is sex specific. These clinical findings have been attributed to sex differences in immune responsiveness. The aim of the present study was to investigate sex differences in monocyte-derived cytokine production response upon stimulation with the gram-negative stimulus lipopolysaccharide (LPS) using cytokine data from 15 study populations. Individual data on ex vivo cytokine production response upon stimulation with LPS in whole blood were available for 4,020 subjects originating from these 15 study populations, either from the general population or from patient populations with specific diseases. Men had a stronger cytokine production response than women to LPS for tumour necrosis factor-α, interleukin (IL)-6, IL-12, IL-1β, IL-1RA, and IL-10, but not for interferon-γ. The granulocyte-macrophage colony-stimulating factor production response was lower in men than in women. These sex differences were independent of chronological age. As men had higher monocyte concentrations, we normalized the cytokine production responses for monocyte concentration. After normalization, the sex differences in cytokine production response to LPS disappeared, except for IL-10, for which the production response was lower in men than in women. A sex-based approach to interpreting immune responsiveness is crucial.

Evidence for genetic correlation between human cerebral white matter microstructure and inflammation

White matter microstructure is affected by immune system activity via the actions of circulating pro-inflammatory cytokines. Although white matter microstructure and inflammatory measures are significantly heritable, it is unclear if overlapping genetic factors influence these traits in humans. We conducted genetic correlation analyses of these traits using randomly ascertained extended pedigrees from the Genetics of Brain Structure and Function Study (N = 1862, 59% females, ages 18-97 years; 42 ± 15.7). White matter microstructure was assessed using fractional anisotropy (FA) calculated from diffusion tensor imaging (DTI). Circulating levels (pg/mL) of pro-inflammatory cytokines (IL-6, IL-8, and TNFα) phenotypically associated with white matter microstructure were quantified from blood serum. All traits were significantly heritable (h² ranging from 0.41 to 0.66 for DTI measures and from 0.18 to 0.30 for inflammatory markers). Phenotypically, higher levels of circulating inflammatory markers were associated with lower FA values across the brain (r = -.03 to r = -.17). There were significant negative genetic correlations between most DTI measures and IL-8 and TNFα, although effects for TNFα were no longer significant when covarying for body mass index. Genetic correlations between DTI measures and IL-6 were not significant. Understanding the genetic correlation between specific inflammatory markers and DTI measures may help researchers focus questions related to inflammatory processes and brain structure.

A genome-wide association study-derived polygenic score for interleukin-1β is associated with hippocampal volume in two samples

Accumulating research suggests that the pro-inflammatory cytokine interleukin-1β (IL-1β) has a modulatory effect on the hippocampus, a brain structure important for learning and memory as well as linked with both psychiatric and neurodegenerative disorders. Here, we used an imaging genetics strategy to test an association between an IL-1β polygenic score and hippocampal volume in two independent samples. Our polygenic score was derived using summary statistics from a recent genome-wide association study of circulating cytokines that included IL-1β (N = 3,309). In the first sample of 512 non-Hispanic Caucasian university students (274 women, mean age 19.78 ± 1.24 years) from the Duke Neurogenetics Study, we identified a significant positive correlation between IL-1β polygenic scores and hippocampal volume. This positive association was successfully replicated in a second sample of 7,960 white British volunteers (4,158 women, mean age 62.63 ± 7.45 years) from the UK Biobank. Our results lend further support in humans, to the link between IL-1β and the structure of the hippocampus.

Inflammation in older subjects with early- and late-onset depression in the NESDO study: a cross-sectional and longitudinal case-only design

OBJECTIVE

Different biological mechanisms may underlie depression beginning in early life (early-onset) and depression beginning later in life (late-onset). Although the relation between inflammation and depression has been studied extensively, the distinct role of inflammation in early and late-onset depression in older patients has not been addressed before. In the cross-sectional part of this study, we explored differences in levels of circulating inflammatory markers and cytokine levels in lipopolysaccharide (LPS) stimulated whole blood between older subjects with a late-life onset depression (≥60 years) and older subjects with an early-onset depression (<60 years). Secondly, in a 2-year follow-up study, we examined if circulating and stimulated inflammatory markers influenced the change in Inventory of Depressive Symptomatology (IDS) scores, and if this relation was different for early- and late-onset depression.

METHODS

The study was part of the Netherlands Study of Depression in Older Persons (NESDO). We included 350 patients, all aged 60 and older, with a depressive episode in the previous 6 months: 119 with a late-onset depression and 231 with an early-onset depression. Blood samples were collected and CRP, IL-6, NGAL, GDF15, and, LPS plasma levels were determined and whole blood was LPS stimulated and cytokine levels IL-1β, IL-6, TNFα, IFNγ, IL-10, and IL-1 receptor antagonist (IL-1ra) were determined.

RESULTS

After adjustment for demographics, health indicators, and medication use, increased plasma CRP levels were more strongly associated with late-onset depression than early-onset depression (OR [95% CI]: 1.43 [1.05-1.94]). In the longitudinal analyses, higher circulating IL-6 levels were associated with a significantly slower decline in IDS scores in the crude and the adjusted models (p ≤ 0.027). This relation was not different between late- and early-onset depression. Other circulating and stimulated inflammatory markers were not associated with late- and/or early-onset depression.

CONCLUSIONS

This study provides preliminary evidence that low-grade inflammation is more strongly associated with late-onset than early-onset depression in older adults, suggesting a distinct inflammatory etiology for late-onset depression. Cytokine production capacity did not distinguish between early- and late-onset depression.

Cell-intrinsic regulation of peripheral memory-phenotype T cell frequencies

Memory T and B lymphocyte numbers are thought to be regulated by recent and cumulative microbial exposures. We report here that memory-phenotype lymphocyte frequencies in B, CD4 and CD8 T-cells in 3-monthly serial bleeds from healthy young adult humans were relatively stable over a 1-year period, while Plasmablast frequencies were not, suggesting that recent environmental exposures affected steady state levels of recently activated but not of memory lymphocyte subsets. Frequencies of memory B and CD4 T cells were not correlated, suggesting that variation in them was unlikely to be determined by cumulative antigenic exposures. Immunophenotyping of adult siblings showed high concordance in memory, but not of recently activated lymphocyte subsets. To explore the possibility of cell-intrinsic regulation of T cell memory, we screened effector memory-phenotype T cell (TEM) frequencies in common independent inbred mice strains. Using two pairs from these strains that differed predominantly in either CD4 TEM and/or CD8 TEM frequencies, we constructed bi-parental bone marrow chimeras in F1 recipient mice, and found that memory T cell frequencies in recipient mice were determined by donor genotypes. Together, these data suggest cell-autonomous determination of memory T niche size, and suggest mechanisms maintaining immune variability.

Are toll-like receptors potential drug targets for atherosclerosis? Evidence from genetic studies to date

Low-density lipoprotein cholesterol lowering, most notably via statin therapy, has successfully reduced the burden of coronary artery disease (CAD) in recent decades. However, the residual risk remaining even after aggressive lipid lowering has renewed interest in alternative targets. Anti-inflammatory drugs are thought to have much potential in this context, but side effects associated with long-term use of conventional anti-inflammatories, such as NSAIDs and glucocorticoids, preclude their use as preventive agents for CAD. Evidence from epidemiological studies and murine models of atherosclerosis suggests that toll-like receptors (TLRs) may have utility as targets for more focused anti-inflammatories, but it remains unclear if this pathway is causally related to CAD in man. Here, we review recent insight into this question gained from genetic studies of cardiovascular risk and innate immune function, focussing on the potential of Mendelian randomisation approaches based on intracellular-signalling pathways to identify and prioritise targets for drug development.

GWAS for Interleukin-1β levels in gingival crevicular fluid identifies IL37 variants in periodontal inflammation

There is no agnostic GWAS evidence for the genetic control of IL-1β expression in periodontal disease. Here we report a GWAS for "high" gingival crevicular fluid IL-1β expression among 4910 European-American adults and identify association signals in the IL37 locus. rs3811046 at this locus (p = 3.3 × 10-22) is associated with severe chronic periodontitis (OR = 1.50; 95% CI = 1.12-2.00), 10-year incident tooth loss (≥3 teeth: RR = 1.33; 95% CI = 1.09-1.62) and aggressive periodontitis (OR = 1.12; 95% CI = 1.01-1.26) in an independent sample of 4927 German/Dutch adults. The minor allele at rs3811046 is associated with increased expression of IL-1β in periodontal tissue. In RAW macrophages, PBMCs and transgenic mice, the IL37 variant increases expression of IL-1β and IL-6, inducing more severe periodontal disease, while IL-37 protein production is impaired and shows reduced cleavage by caspase-1. A second variant in the IL37 locus (rs2708943, p = 4.2 × 10-7) associates with attenuated IL37 mRNA expression. Overall, we demonstrate that IL37 variants modulate the inflammatory cascade in periodontal disease.

Stability of individual LPS-induced ex vivo cytokine release in a whole blood assay over a five-year interval

OBJECTIVE

In epidemiological and clinical studies, whole blood assay (WBA) has been used as a measure to characterize inter-individual differences in the cytokine response of individuals exposed to inflammatory agents, such as endotoxins. Several short-time repeatability studies have shown stable cytokine levels in individuals over periods of days, weeks or months, but little is known about the long-term stability of cytokine reactivity.

METHODS

We studied cytokine response levels in LPS-stimulated whole blood in a cohort of 193 farmers and agricultural industry workers at two time points with a five-year interval.

RESULTS

IL-10 and IL-1β responses measured with a five-year time interval showed a weak positive correlation (r = 0.22 and 0.27, respectively), whereas no correlation was observed for TNFα (r = 0.06). Cytokine reactivity measured repeatedly at the same time point showed high correlations (IL-10 r = 0.80, IL-1β r = 0.53 and TNFα r = 0.74), suggesting that the observed weak correlations over time are reflective of actual variations in cytokine reactivity over time.

CONCLUSIONS

Repeatability of ex vivo cytokine reactivity showed to be differential for the measured cytokines, being more stable for IL-10 and IL-1β than for TNFα. However, in general, repeatability of ex vivo cytokine reactivity was weak, reflecting that cytokine reactivity can mostly be explained by (short term) intra-individual (immunological) or time varying environmental factors and less by genetic or other time-invariant factors. Therefore, WBA should be regarded as a viable tool to study relationships with current health status and exposure, and only partially as a predictor for a future response.

Genetic ancestry and population differences in levels of inflammatory cytokines in women: Role for evolutionary selection and environmental factors

Selection pressure due to exposure to infectious pathogens endemic to Africa may explain distinct genetic variations in immune response genes. However, the impact of those genetic variations on human immunity remains understudied, especially within the context of modern lifestyles and living environments, which are drastically different from early humans in sub Saharan Africa. There are few data on population differences in constitutional immune environment, where genetic ancestry and environment are likely two primary sources of variation. In a study integrating genetic, molecular and epidemiologic data, we examined population differences in plasma levels of 14 cytokines involved in innate and adaptive immunity, including those implicated in chronic inflammation, and possible contributing factors to such differences, in 914 AA and 855 EA women. We observed significant differences in 7 cytokines, including higher plasma levels of CCL2, CCL11, IL4 and IL10 in EAs and higher levels of IL1RA and IFNα2 in AAs. Analyses of a wide range of demographic and lifestyle factors showed significant impact, with age, education level, obesity, smoking, and alcohol intake, accounting for some, but not all, observed population differences for the cytokines examined. Levels of two pro-inflammatory chemokines, CCL2 and CCL11, were strongly associated with percent of African ancestry among AAs. Through admixture mapping, the signal was pinpointed to local ancestry at 1q23, with fine-mapping analysis refined to the Duffy-null allele of rs2814778. In AA women, this variant was a major determinant of systemic levels of CCL2 (p = 1.1e-58) and CCL11 (p = 2.2e-110), accounting for 19% and 40% of the phenotypic variance, respectively. Our data reveal strong ancestral footprints in inflammatory chemokine regulation. The Duffy-null allele may indicate a loss of the buffering function for chemokine levels. The substantial immune differences by ancestry may have broad implications to health disparities between AA and EA populations.

Specific features of human monocytes activation by monophosphoryl lipid A

We deciphered the mechanisms of production of pro- and anti-inflammatory cytokines by adherent human blood mononuclear cells (PBMC) activated by lipopolysaccharide (LPS) or monophosphoryl lipid A (MPLA). Both LPS and MPLA induced tumor necrosis factor (TNF) production proved to be dependent on the production of interleukin-1β (IL-1β). Of note, MPLA induced IL-1β release in human adherent PBMCs whereas MPLA was previously reported to not induce this cytokine in murine cells. Both LPS and MPLA stimulatory effects were inhibited by Toll-like receptor-4 (TLR4) antagonists. Only monocytes activation by LPS was dependent on CD14. Other differences were noticed between LPS and MPLA. Among the different donors, a strong correlation existed in terms of the levels of TNF induced by different LPSs. In contrast, there was no correlation between the TNF productions induced by LPS and those induced by MPLA. However, there was a strong correlation when IL-6 production was analyzed. Blocking actin polymerization and internalization of the agonists inhibited MPLA induced TNF production while the effect on LPS induced TNF production depended on the donors (i.e. high TNF producers versus low TNF producers). Finally, conventional LPS, tolerized adherent PBMCs to TLR2 agonists, while MPLA primed cells to further challenge with TLR2 agonists.

Changes in pro-inflammatory cytokine levels and late-life depression: A two year population based longitudinal study

Longitudinal associations of cytokine levels with depression are unclear. This study aimed to investigate cross-sectional and prospective associations between five serum pro-inflammatory cytokine levels and late-life depression. 732 Korean people aged 65+ were evaluated at baseline. Of 631 without depression (Geriatric Mental State schedule) at baseline, 521 (83%) were followed over a 2 year period and incident depression was ascertained. Serum tumor necrosis factor-α, interleukin (IL)-1α, IL-1β, IL-6, and IL-8 levels were assayed at both baseline and follow-up. Associations between cytokine levels and depressive status were evaluated using linear regression models, considering potential covariates (demographics, cognitive function, disability, lifestyle factors, and vascular risk factors) and applying Bonferroni corrections. Prevalent depression at baseline was significantly associated with higher contemporaneous levels of IL-1β and IL-8, independent of relevant covariates and after applying Bonferroni corrections. In the analyses of the five cytokine levels in combination, independent associations were found between prevalent depression and increased numbers of cytokines at higher levels at baseline. Incident depression was significantly associated with increases in IL-1β, IL-6, and IL-8 levels during the follow-up independent of relevant covariates and after applying Bonferroni corrections. In combination analyses, incident depression was independently associated with higher numbers of cytokines showing increasing levels over the same follow-up period. However, incident depression was not predicted by higher baseline pro-inflammatory cytokine levels in any analysis. Our findings suggest that depression might affect serum cytokines alterations and lead to inflammatory processes in late-life.

Identification of Functional Genetic Polymorphisms at IL-10 Promoter Region and their Association with Risk of Ischemic Stroke in Chinese Han Population

BACKGROUND

Pleiotropic cytokine interleukin-10 (IL-10) has been suggested as modifying risk for atherosclerosis. Promoter region genetic polymorphism of IL-10 gene is known to be associated with the level of IL-10 production. Through these effects, they might be involved with the ischemic stroke (IS). Our aim was to assess the nature of the functional polymorphisms in IL-10 promoter and any links with IS in Chinese Han population.

METHODS

The IL-10 -1082 G>A, -819 C>T and -592 C>A functional polymorphisms were determined by TaqMan SNP Genotyping assays in 1296 subjects (648 IS patients diagnosed by CTs or/and magnetic resonance imaging (MRI) and 648 normal healthy controls from Chinese Han Population). Multivariate logistic regression analysis was used to show the association between the IL-10 genotypes and the IS events.

RESULTS

We found that the CC genotype of -819 C>T was more common in controls than IS subjects (P<0.05, corrected for multiple testing) in the Han population. CC carriage may be associated with the decreased risk of IS in the Han ethnic group (OR 0.65, 95% CI 0.43-0.97). In addition, the CC genotype in -592 C>A and GG genotype in -1082 G>A are all extremely low in Chinese Han cases and controls.

CONCLUSIONS

The G allele frequency at the -1082 promoter region of IL-10 was rare in Chinese Han population which are diffierent from American/European populations.. IL-10 -819 C>T may be an independent protective factor for IS in the Chinese Han population.

Longitudinal Associations Between Serum Cytokine Levels and Dementia

Background: The purpose of this study was to investigate whether long-term inflammation is related to the incidence of dementia in a prospective observational study. Methods: In total, 732 Korean community-dwelling elderly people >65 years were evaluated at baseline. Of the 625 without dementia, 518 (83%) were followed over a 2.4-years period, and the incidence of dementia was determined. Cytokine [interleukin (IL)-1α, IL-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α] levels were measured at baseline and follow-up. The individual and combined effects of cytokine levels on dementia were evaluated after adjusting for potential covariates (lifestyle factors, demographics, disability, cognitive function, and presence of the APOE e4 allele) and a Bonferroni correction. Results: Incident dementia was associated with increased serum cytokine levels after 2 years; the association remained significant for TNF-α, IL1-α, and IL-1β concentrations even after applying a Bonferroni correction. The analysis of the combined effects of the five cytokines showed independent associations between increases in the summed number of higher cytokine levels, between baseline and follow-up. However, incident dementia was not expected based on higher baseline pro-inflammatory cytokine levels. Conclusion: Our results suggest that dementia may precede changes in serum cytokine levels and inflammatory processes, rather than resulting from elevated pro-inflammatory cytokines.

The role of anxious distress in immune dysregulation in patients with major depressive disorder

Although depression with anxious distress appears to be a clinically relevant subtype of major depressive disorder (MDD), whether it involves specific pathophysiology remains unclear. Inflammation has been implicated, but not comprehensively studied. We examined within a large MDD sample whether anxious distress and related anxiety features are associated with differential basal inflammation and innate cytokine production capacity. Data are from 1078 MDD patients from the Netherlands Study of Depression and Anxiety. In addition to the DSM-5 anxious distress specifier, we studied various dimensional anxiety scales (e.g. Inventory of Depressive Symptomatology anxiety arousal subscale [IDS-AA], Beck Anxiety Inventory [BAI], Mood and Anxiety Symptoms Questionnaire Anxious Arousal scale [MASQ-AA]). The specifier was constructed using five self-report items from the IDS and BAI. Basal inflammatory markers included C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α. Innate production capacity was assessed by 13 lipopolysaccharide (LPS)-stimulated inflammatory markers. Basal and LPS-stimulated inflammation index scores were created. Basal inflammation was not associated with anxious distress (prevalence = 54.3%) in MDD patients, except for a modest positive association for BAI score. However, anxious distress was associated with higher LPS-stimulated levels (interferon-γ, IL-6, monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, matrix metalloproteinase (MMP)-2, TNF-α, LPS-stimulated index). Other anxiety indicators (anxious distress specifier score, BAI, MASQ-AA) were also associated with increased innate production capacity. Within a large MDD sample, the anxious distress specifier was associated with increased innate cytokine production capacity but not with basal inflammation. Results from dimensional anxiety indicators largely confirm these results. These findings provide new insight into the pathophysiology of anxious depression.

Associations of Tumor Necrosis Factor-α and Interleukin-1β Levels and Polymorphisms with Post-Stroke Depression

OBJECTIVE

Proinflammatory cytokines have been implicated in the pathophysiology of post-stroke depression (PSD), and their production levels are influenced by the transcriptional activity of genetic polymorphisms. The present study aimed to investigate the roles of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the serum on the risk of PSD while taking into account the TNF-α -850C/T and -308G/A polymorphisms and the IL-1β -511C/T and +3953C/T polymorphisms.

METHODS

A total of 286 patients were evaluated at 2 weeks post stroke and 222 (78%) of these patients were followed up 1 year later. Depressive (major or minor) disorders were diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria during both examinations; evaluations of cytokine concentrations and polymorphisms and demographic and clinical covariates were performed at 2 weeks. The effects of TNF-α and IL-1β concentrations and genotypes on PSD status were investigated using multivariate logistic regression models.

RESULTS

Higher TNF-α levels were associated with PSD at 2 weeks in the presence of the -850T allele with a significant interaction term; higher IL-1β levels were associated with PSD at 2 weeks in the presence of the -511T allele with a borderline significant interaction term and with any +3953C/T polymorphism without a significant interaction term. No associations were found with PSD at 1 year.

CONCLUSIONS

These findings indicate the important roles that TNF-α and IL-1β serum levels play regarding the risk of PSD, particularly during the acute phase of stroke and in patients with genetic susceptibility.

The Impact of Tumor Necrosis Factor-α and Interleukin-1β Levels and Polymorphisms on Long-Term Stroke Outcomes

Background: The accuracy of predictions regarding disability that sets in after stroke could be improved by using blood biomarker measurements. This study aimed to investigate the roles of serum tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1β concentrations and polymorphisms in stroke outcomes. Methods: In total, 286 patients were evaluated at the time of admission and at 2 weeks after stroke, and 222 of these patients (78%) were followed up for 1 year to evaluate the consequences of stroke during both the acute and chronic stages. Stroke outcomes were dichotomized into good and poor using the modified Rankin Scale. Results: The association of TNF-α and IL-1β concentrations and their corresponding genotypes with stroke outcomes was investigated using multivariate logistic regression. Higher TNF-α levels were associated with poor outcomes 1 year after stroke in the presence of the –850T and –308A alleles, and IL-1β levels were associated with poor 1-year stroke outcomes in the presence of the –511T and +3953T alleles. No such associations were found at 2 weeks after stroke. Conclusions: These data provide evidence that serum TNF-α and IL-1β concentrations are related to poor long-term outcomes after stroke in the presence of particular alleles.

Exotoxins and endotoxins: Inducers of inflammatory cytokines

Endotoxins and exotoxins are among the most potent bacterial inducers of cytokines. During infectious processes, the production of inflammatory cytokines including tumor necrosis factor (TNF), interleukin-1β (IL-1β), gamma interferon (IFNγ) and chemokines orchestrates the anti-infectious innate immune response. However, an overzealous production, leading up to a cytokine storm, can be deleterious and contributes to mortality consecutive to sepsis or toxic shock syndrome. Endotoxins of Gram-negative bacteria (lipopolysaccharide, LPS) are particularly inflammatory because they generate auto-amplificatory loops after activation of monocytes/macrophages. LPS and numerous pore-forming exotoxins also activate the inflammasome, the molecular platform that allows the release of mature IL-1β and IL-18. Among exotoxins, some behave as superantigens, and as such activate the release of cytokines by T-lymphocytes. In most cases, pre-exposure to exotoxins enhances the cytokine production induced by LPS and its lethality, whereas pre-exposure to endotoxin usually results in tolerance. In this review we recall the various steps, which, from the very early discovery of pyrogenicity induced by bacterial products, ended to the discovery of the endogenous pyrogen. Furthermore, we compare the specific characteristics of endotoxins and exotoxins in their capacity to induce inflammatory cytokines.

The Mouse Papillomavirus Infection Model

The mouse papillomavirus (MmuPV1) was first reported in 2011 and has since become a powerful research tool. Through collective efforts from different groups, significant progress has been made in the understanding of molecular, virological, and immunological mechanisms of MmuPV1 infections in both immunocompromised and immunocompetent hosts. This mouse papillomavirus provides, for the first time, the opportunity to study papillomavirus infections in the context of a small common laboratory animal for which abundant reagents are available and for which many strains exist. The model is a major step forward in the study of papillomavirus disease and pathology. In this review, we summarize studies using MmuPV1 over the past six years and share our perspectives on the value of this unique model system. Specifically, we discuss viral pathogenesis in cutaneous and mucosal tissues as well as in different mouse strains, immune responses to the virus, and local host-restricted factors that may be involved in MmuPV1 infections and associated disease progression.

A Perspective on the Role of Computational Models in Immunology

This is an exciting time for immunology because the future promises to be replete with exciting new discoveries that can be translated to improve health and treat disease in novel ways. Immunologists are attempting to answer increasingly complex questions concerning phenomena that range from the genetic, molecular, and cellular scales to that of organs, whole animals or humans, and populations of humans and pathogens. An important goal is to understand how the many different components involved interact with each other within and across these scales for immune responses to emerge, and how aberrant regulation of these processes causes disease. To aid this quest, large amounts of data can be collected using high-throughput instrumentation. The nonlinear, cooperative, and stochastic character of the interactions between components of the immune system as well as the overwhelming amounts of data can make it difficult to intuit patterns in the data or a mechanistic understanding of the phenomena being studied. Computational models are increasingly important in confronting and overcoming these challenges. I first describe an iterative paradigm of research that integrates laboratory experiments, clinical data, computational inference, and mechanistic computational models. I then illustrate this paradigm with a few examples from the recent literature that make vivid the power of bringing together diverse types of computational models with experimental and clinical studies to fruitfully interrogate the immune system.

Estimating heritable genetic contributions to innate immune and endocrine phenotypic correlations: A need to explore repeatability

The immune system plays an important role in enhancing an individual's ability to survive in a world inhabited by pathogens and parasites. The innate immune system is regulated by processes encoded in an individual's genome, providing an avenue for selection to act on this system, as well as the phenotypic relationships generated between this system and other traits of interest. While relationships between innate immunity and endocrine traits (e.g. testosterone) have been reported often in the literature, these relationships are complex and may differ under varying environmental conditions. To better understand the relative contribution of innate immunity (or an endocrine or behavioral trait) to a phenotypic correlation with another trait, an estimation of the underlying heritable genetic variation of the trait of interest is needed. An upper level estimate of the heritability of such traits can be obtained from calculating its repeatability. We conducted a literature review to determine how often repeated samples of measures of innate immune function were conducted and repeatability estimates obtained. This review revealed a very limited number of repeatability estimates, with a large range (0.0-0.9); estimates were exclusively from livestock that have undergone strong artificial selection. This observation of the present literature suggests more work is needed in non-domesticated and free-living animals to begin to understand the underlying genetic contribution of innate immune function to phenotypic correlations of interest (e.g. testosterone and immunity) to behavioral ecologists, evolutionary physiologists and ecoimmunologists.

Patterns of immune development in urban preschoolers with recurrent wheeze and/or atopy

BACKGROUND

Disadvantaged urban children have high rates of allergic diseases and wheezing, which are diseases associated with type 2-biased immunity.

OBJECTIVE

We sought to determine whether environmental exposures in early life influence cytokine responses that affect the development of recurrent wheezing illnesses and allergic sensitization.

METHODS

A birth cohort of 560 urban families was recruited from neighborhoods with high rates of poverty, and 467 (83%) children were followed until 3 years of age. Cytokine responses were measured in blood cell samples obtained at birth (cord blood) and ages 1 and 3 years. Cytokine responses were examined in relation to personal characteristics and environmental exposures to allergens and endotoxin and to the development of allergic sensitization and recurrent wheeze assessed at age 3 years.

RESULTS

Cytokine responses generally increased with age, but responses at birth were poorly predictive for those at ages 1 and 3 years. Exposure to certain allergens (cockroach, mouse, dust mite) was significantly associated with enhanced cytokine responses at age 3 years, including IFN-α and IL-10 responses to certain stimulants and responses to phytohemagglutinin. Regarding the clinical outcomes, reduced LPS-induced IL-10 responses at birth were associated with recurrent wheeze. In contrast, reduced respiratory syncytial virus-induced IL-8 responses and increased 5'-cytosine-phosphate-guanine-3' (CpG)-induced IL-12p40 and allergen-induced IL-4 responses were associated with atopy.

CONCLUSIONS

These findings suggest that diverse biologic exposures, including allergens and endotoxin, in urban homes stimulate the development of cytokine responses in early life, and that cytokine responses to specific microbial and viral stimuli are associated with the development of allergic sensitization and recurrent wheeze.

Neonatal levels of adiponectin, interleukin-10 and interleukin-12 are associated with the risk of developing type 1 diabetes in childhood and adolescence: A nationwide Danish case-control study

BACKGROUND/AIM

An in-depth understanding of the early phase of type 1 diabetes (T1D) pathogenesis is important for targeting primary prevention. We examined if 14 preselected mediators of immune responses differed in neonates that later developed T1D compared to control neonates.

METHODS

The study is a case-control study with a 1:2 matching. The individuals were born between 1981 through 2002. Cases were validated using the National Patient Register and the Danish Childhood Diabetes Register. Interleukin(IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-12p70, interferon gamma, tumor necrosis factor alpha, transforming growth factor beta 1 (active form), leptin, adiponectin, c-reactive protein, mannose-binding lectin and soluble triggering receptor expressed on myeloid cells-1 were measured by using a flowmetric Luminex xMAP® technology. We tested two models both including a number of possible confounders. In the first model (model 1) we also adjusted for HLA-DQB1 genotype. A total of 1930 groups of assay-matched cases and controls (4746 individuals) were included in the statistical analyses.

RESULTS

Adiponectin was negatively associated with later risk of T1D in both models (relative change (RC), model 1: 0.95, P=0.046 and model 2: 0.95, P=0.006). IL-10 and IL-12 were both positively associated with T1D risk in the model 2 (RC, 1.19, P=0.006 and 1.07, P=0.02, respectively)-these results were borderline significant in model 1, but showed the same direction as the results from model 2.

CONCLUSIONS

Our results indicate that specific immunological signatures are already present at time of birth in children developing T1D before the age of 18years.

Testing the mate-choice hypothesis of the female orgasm: disentangling traits and behaviours

BACKGROUND

The evolution of the female orgasm in humans and its role in romantic relationships is poorly understood. Whereas the male orgasm is inherently linked to reproduction, the female orgasm is not linked to obvious reproductive or survival benefits. It also occurs less consistently during penetrative sex than does the male orgasm. Mate-choice hypotheses posit that the wide variation in female orgasm frequency reflects a discriminatory mechanism designed to select high-quality mates.

OBJECTIVE

We aimed to determine (1) whether women report that their orgasm frequency varies between partners, (2) whether this variation reflects mates' personal characteristics, and (3) whether this variation reflects own and partner sexual behaviour during intercourse.

DESIGN

We collected survey data from 103 women who rated (1) the extent to which their orgasm frequency varied between partners, (2) the characteristics of previous sexual partners who induced high-orgasm frequency and those who induced low-orgasm frequency, and (3) the specific behaviours during sex with those partners. This is the first study to test within-woman variation in orgasm and partner traits.

RESULTS

Overall, women reported variation in their orgasm rates with different partners. Partners who induced high-orgasm rates were rated as more humorous, creative, warm, faithful, and better smelling than partners who induced low-orgasm rates, and also engaged in greater efforts to induce partner orgasm.

CONCLUSIONS

Some assumptions and predictions of mate-choice hypotheses of female orgasm were supported, while other aspects of our findings provide reasons to remain sceptical.