Pathogenic and obesogenic factors associated with inflammation in Chinese children, adolescents and adults

Sandwiched Grandparents and Biological Health Risks in China

This study examined the cross-sectional associations between intergenerational caregiving and health risks among sandwiched Chinese grandparents who provide care to grandchildren, great-grandparents, or both. Drawing on biomarker data from the 2011 wave of the China Health and Retirement Longitudinal Study (N range = 2,189-3,035), we measured age-related biological health risks of hypertension, diabetes, inflammation, and allostatic load. We found that health risks did not necessarily increase with the intensity of intergenerational caregiving. Providing care to grandchildren and great-grandparents simultaneously was not as detrimental to health as reported in earlier studies from the United States. Sandwiched grandparents could benefit from providing care to grandchildren or great-grandparents only. These unexpected findings might be related to the cultural mandates of filial piety and family solidarity in China. Grandfathers and grandmothers experienced different associations between varying types of intergenerational caregiving and health risks.

Adiposity and pathogen exposure: An investigation of response to iron supplementation and hypothesized predictors in anemic pre-school-aged children living in a dual burden environment

OBJECTIVES

Peruvians are experiencing rapid dietary and lifestyle changes, resulting in a phenomenon known as the "dual burden of disease." A common manifestation of the dual burden in individuals is the co-occurrence of overweight and anemia. Despite recent initiatives introduced to address these concerns, rates continue to be public health concerns. This study investigates the relationship between immune activation and lack of response to iron supplementation after 1 month of treatment and explores variation in body fat stores as a potential moderator between immune function and response to treatment.

METHODS

Data come from children, aged 2-5 years (n = 50) from a peri-urban community in Lima, Peru. Multivariate logistic regression models were used to explore the associations between response to treatment (Hb > =11.0 g/dl) after 1 month of treatment), markers of immune activation (C-reactive protein [CRP] and reported morbidity symptoms), and measures of body fat (waist-to-height ratio, triceps skinfold thickness, and body mass index [BMI]).

RESULTS

We found that high CRP is associated with a lack of response to iron supplementation after 1 month of treatment and that BMI z-score may moderate this association. Generally, larger body size is associated with response to iron supplementation whether or not the children in this sample have high immune activation. However, the probability of anemic children responding to iron supplementation treatment differed across adiposity measures.

CONCLUSIONS

Our finding suggesting that adiposity and CRP influence response to iron supplementation, furthers our understanding of the relationship between inflammation and anemia treatment in children and has both theoretical and public health implications.

Variability of C-reactive protein in first-generation Ecuadorian immigrants living in the United States

OBJECTIVES

Establish the variability of C-reactive protein (CRP) within a population of first-generation immigrants living in the United States. Prior work has theorized that individuals with high levels of childhood pathogen exposure may have lower CRP levels in adulthood, and therefore that for these individuals, CRP may not be as accurate an index of chronic disease risk related to low-level inflammation as is presumed based on data from wealthy populations. This potentially has major implications for the interpretation of CRP as a biomarker of chronic inflammation.

METHODS

This longitudinal study collected a total of 125 dried blood spot (DBS) samples from 31 participants (median 4 samples each) and CRP levels in these DBS were assayed by enzyme-linked immunosorbant assay. Surveys were administered to characterize childhood pathogen exposure, and current illness. Variance was estimated using mixed effects regression models.

RESULTS

On average, participants were adults (mean = 41.9 years old) who had immigrated to the United States nearly 20 years prior to the study and had nearly universally experienced childhood helminth infection and other major pathogen exposures. Median serum-equivalent CRP was 0.77 mg/L. Individuals reliably differed in subacute CRP levels, and, depending on whether untransformed or log-transformed CRP was the outcome variable, 45% or 62% of variance in CRP was attributable to between-individual differences.

CONCLUSIONS

The variability of CRP levels in individuals with relatively high childhood pathogen exposure is comparable to previously reported studies in North America and Europe. However, CRP values are relatively low. CRP is an appropriate measure of subacute inflammation in this sample.

Does the Punishment Fit the Crime (and Immune System)? A Potential Role for the Immune System in Regulating Punishment Sensitivity

Although the criminal justice system is designed around the idea that individuals are invariant in their responses to punishment, research indicates that individuals exhibit a tremendous amount of variability in their punishment sensitivity. This raises the question of why; what are the individual- and situation-level variables that impact a person’s sensitivity to punishment? In the current research, we synthesize theory and research on inflammation, learning, and evolutionary biology to examine the relationship between inflammatory activity and sensitivity to punishment. These theories combine to predict that inflammatory activity – which is metabolically costly and reflects a context in which the net payoff associated with future oriented behaviors is diminished – will decrease sensitivity to punishment, but not rewards. Consistent with this hypothesis, Study 1 found that in U.S. states with a higher infectious disease burden (a proxy for average levels of inflammatory activity) exhibit harsher sentencing in their criminal justice systems. Studies 2 and 3 experimentally manipulated variables known to impact bodily inflammatory activity and measured subsequent punishment and reward sensitivity using a probabilistic selection task. Results revealed that (a) increasing inflammation (i.e., completing the study in a dirty vs. clean room) diminished punishment sensitivity (Study 2), whereby (b) administering a non-steroidal anti-inflammatory drug, suppressing inflammatory activity, enhanced it. No such changes were found for reward sensitivity. Together, these results provide evidence of a link between the activities of the immune system and punishment sensitivity, which may have implications for criminal justice outcomes.

Chronic stress and age-related pattern of blood pressure: A cross-sectional study in rural China

OBJECTIVE

Chronic stress is a risk factor for hypertension in adults. However, there is conflicting evidence for older adults. We hypothesized that age-related arterial stiffening, which leads to a lower blood pressure (especially diastolic blood pressure [DBP]), is more pronounced among older adults with high vs low stress. The objectives of this study were (a) to investigate age-related trends in systolic and DBPs among adults in rural Fujian, China, and (b) to examine differences in age-related blood pressure trends according to levels of stress by using Epstein-Barr virus (EBV) antibody titer as a marker of chronic stress status.

METHODS

We collected cross-sectional data from 764 rural community-dwelling adults in rural Fujian, China (mean age = 59.4). Participants were categorized into high and low stress groups by median split of EBV antibody titer. A least-squares regression analysis was used to investigate the association between age and blood pressures.

RESULTS

We observed an inverted U-shaped association between age and DBP, while there was a linear association between age and systolic blood pressure in the overall sample. When stratified by stress, the inverted U-shaped associations with age (both systolic and DBPs) were seen only among those with high stress; DBP peaked at the age of ~68 years, and the declining trend later in life was more clearly observed among those with high chronic stress.

DISCUSSION

Decrease of DBP was more pronounced among older adults with high vs low chronic stress in rural China.

Water, food, and the dual burden of disease in Galápagos, Ecuador

OBJECTIVE

Rapid development in low- and middle-income countries (LMIC) has led to changes in diet that have outpaced water and sanitation improvements, contributing to a dual burden of overweight and noncommunicable disease risk factors (OWT/NCD) and undernutrition and infectious disease symptoms (UND/ID) within individuals and households. Yet, little work has examined the joint impact of water and food exposures on the development of the dual burden.

METHODS

We use data from Ecuador's nationally representative Encuesta Nacional de Salud y Nutrición (ENSANUT-ECU) to test whether water access and quality and diet quality and security are associated with OWT/NCD and UND/ID among 1119 children and 1582 adults in Galápagos. Adjusted multinomial and logistic models were used to test the separate and joint associations between water and food exposures and the dual burden and its components at the individual and household levels.

RESULTS

The prevalence of the dual burden of OWT/NCD and UND/ID was 16% in children, 33% in adults, and 90% in households. Diet quality was associated with a higher risk of dual burden in individuals and households. Mild food insecurity was positively associated with the risk of dual burden at the household level. No water variable separately predicted the dual burden. Joint exposure to poor water access and food insecurity was associated with greater odds of dual burden in households.

CONCLUSION

Our results suggest that unhealthy diets and poor water quality contribute to the dual burden at the individual and household levels. Addressing both food and water limitations is important in LMIC.

The association between family members' migration and Epstein-Barr virus antibody titers among people left behind in rural Fujian, China

OBJECTIVES

In contrast to the health of migrants, which has been extensively studied, little attention has been paid to the health of adults left behind by family members who out-migrated to other locations. This study was performed to investigate the association between being left behind and the Epstein-Barr virus (EBV) antibody titer, which is an indicator of cellular immune functioning previously shown to be associated with psychological stress.

METHODS

A cross-sectional survey was conducted in rural communities in Fujian, China, in 2015. Questionnaire data and dried blood spot samples were collected from 748 adults. A mixed effect regression analysis was conducted to investigate the association.

RESULTS

Results indicated that the EBV antibody titers were higher among people who had been left behind compared with those who had not.

CONCLUSIONS

Our findings suggest that, in rural Fujian, China, family separation following the out-migration of family members is an important determinant of psychological stress.

Physical and mental health of Chinese grandparents caring for grandchildren and great-grandparents

The increasing worldwide prevalence and intensity of grandparenting has attracted an attention to its health implications for caregivers against the backdrop of population aging. Thanks to prolonged life expectancy and reduced infant mortality, extended families that comprise four generations, co-residential or not, are no longer rare in China. The current study examines health consequences when Chinese grandparents provide care to not only grandchildren but also their own elderly parents or parents-in-law (i.e., great-grandparents). Drawing on data from the 2011-2013 China Health and Retirement Longitudinal Study (CHARLS), mental health was captured by levels of life satisfaction and depressive symptoms, and physical health was measured by levels of high sensitivity C-reactive protein (CRP), hypertension, high-risk pulse rate, and diabetes. Overall grandparents who cared for grandchildren only had better mental and physical health, compared with non-caregivers. There was some evidence that the 'sandwich' grandparents who cared for both grandchildren and great-grandparents reported greater life satisfaction, fewer depressive symptoms, and reduced hypertension compared with non-caregivers. The health advantage of caregiving was most pronounced in urban grandfathers whose caregiving conformed to the norm of filial piety and who did so most likely to seek emotional reward instead of an intergenerational time-for-money exchange. In contrast, rural grandmothers were the most vulnerable group and their health disadvantage seemed to arise from caring for great-grandparents. These findings highlight the importance of rural-urban context and gender role in studying the health effects of intergenerational caregiving on Chinese grandparents.

Secondary data analysis to answer questions in human biology

Despite a growing number of publicly available datasets, the use of these datasets for secondary analyses in human biology is less common compared with other fields. Secondary analysis of existing data offers an opportunity for human biologists to ask unique questions through an evolutionary and biocultural lens, allowing for an analysis of cultural and structural nuances that affect health. Leveraging publicly available datasets for human biology research is a way for students and established researchers to complement their data collection, use existing data for master's and doctoral theses, pilot test questions, and use existing data to answer interesting new questions or explore questions at the population level. Here we describe where publicly available data are stored, highlighting some data repositories and how to access them. We then discuss how to decide which dataset is right, depending on the research question. Next, we describe steps to construct datasets, analytical considerations and methodological challenges, best practices, and limitations depending on the structure of the study. We close by highlighting a number of publicly available datasets that have been used by human biologists and other datasets that may be of interest to the community, including research that has been conducted on some example datasets.

Caesarean delivery, immune function and inflammation in early life among Ecuadorian infants and young children

Caesarean delivery has been linked to a number of inflammatory conditions in childhood and adolescence. Yet the mechanisms underlying these associations and their generalizability across contexts with different postnatal feeding and pathogenic exposures remain unclear. This study tests the association between delivery type and three measures of immune function, inflammation, morbidity and leukocyte proportions, in Ecuadorian infants and children aged 6 months to 2 years. Data were collected from mother-child pairs participating in a nationally representative health and nutrition survey Encuesta Nacional de Salud y Nutricion (ENSANUT-ECU) conducted in 2012. The analytic sample includes 828 mothers and infants with delivery information and measured biomarkers. Poisson regression models were used to examine the association between delivery type and markers of immune function, controlling for maternal and infant characteristics, including age, sex, sociodemographic characteristics and medical indications. 40.8% (n=338) of sample infants and children were delivered by caesarean. Compared to those born vaginally, infants born by caesarean were less likely to have elevated C-reactive protein (CRP) [CRP>2 mg/l; risk ratio (RR): 0.76, 95% confidence interval (CI): 0.58-1.00] and more likely to have illness symptoms (RR: 1.22, 95% CI: 1.01-1.46) and elevated basophils (RR: 1.83, 95% CI: 1.03-3.25). No other immune cell proportions differed by delivery type. The results suggest that differences in the perinatal exposures accompanying caesarean delivery may alter immune development and function, particularly in the inflammatory response to infection and in cells involved in the allergic response, across infancy and early childhood. Understanding the pathways linking perinatal exposures to immune development is important for preventing the development of inflammatory conditions.

Multilevel socioeconomic differentials in allostatic load among Chinese adults

Capitalizing on the biomarker data from the 2009 wave of the China Health and Nutrition Survey (CHNS), this study examines the extent to which multilevel socioeconomic status (SES) gets "under the skin" to affect individuals' health, measured by allostatic load (AL). Multilevel analyses suggest that in the context of China's socioeconomic and health transitions, high income, prestigious but sedentary occupations, and high level of urbanization were independently associated with higher AL scores, or increased health risks of physiological dysfunction in cardiovascular, metabolic, inflammation, and urinary systems. Higher educational attainment was related to a decrease in AL, but the significant difference was only observed among the college-educated compared to lower levels of education.

Epstein-Barr virus antibody titer as a stress biomarker and its association with social capital in rural Fujian communities, China

OBJECTIVES

There has been little research on the association between social capital and psychological stress measured by a biomarker, particularly in developing countries. Our objective was to investigate the association between Epstein-Barr virus (EBV) antibody titer, an indicator of cellular immune function previously shown to be associated with psychological stress, and social capital among rural community dwellers in Fujian Province, China.

METHODS

We conducted a cross-sectional survey in seven rural communities in Fujian in 2015. We used questionnaire data and dried blood spot samples for the measurement of biomarkers collected from 734 local residents for the analysis. We conducted a mixed effects regression analysis to investigate the association between EBV antibody titer and four social capital variables, which included cognitive and structural social capital assessed both at individual and community levels.

RESULTS

Community-level structural social capital was inversely associated with psychological stress (coefficient = -0.96, 95% confidence interval [CI] = -1.91, -0.01) while individual-level structural social capital was positively associated with it (coefficient = 0.21, 95% CI = 0.07, 0.36). Neither individual- nor community-level cognitive social capital was associated with psychological stress status.

CONCLUSIONS

In rural Fujian, China, social capital seemed to be an important determinant of psychological health. While living in a community with active social interaction may benefit the residents psychologically, social interaction in the form of strongly bonded relationships may be a source of psychological stress at the individual level due to the potential demands and obligations that may be associated with such connections.

Childhood body mass is positively associated with cesarean birth in Yucatec Maya subsistence farmers

OBJECTIVE

The epidemiologic link between cesarean birth and childhood obesity is unresolved, partly because most studies come from industrialized settings where many post-birth factors affect the risk for obesity. We take advantage of an unusual ethnographic situation where hospital and cesarean birth modes have recently been introduced among Yucatec Maya subsistence farmers, but young children have had minimal exposure to the nutritional transition. While we expect to find very low rates of childhood obesity, we predict that cesarean-born children will be larger and heavier than vaginally born children.

METHODS

Weight and height were collected monthly on 108 children aged 0-5 (3576 observations total). Birth mode and birthweight were collected by maternal interview. Data were analyzed using linear mixed models that compare child growth [Maya population-specific Z-scores for weight-for-age and body mass index-for-age (WAZ and BMIZ)] in cesarean and vaginally born children aged 0-5 years.

RESULTS

The cesarean rate was 20%, no children were obese, and 5% were overweight. Cesarean birth was a significant predictor of child WAZ and BMIZ after accounting for maternal effects, child birthweight, and sex. Children who were born by cesarean to mothers with high BMI had the highest WAZ of all children by 5 years of age, and the highest BMIZ of all children at all ages.

CONCLUSION

Cesarean-born Maya children had higher BMI than vaginally born children, even in the absence of many known confounding factors that contribute to childhood obesity. Child growth was most sensitive to birth mode when mothers had high BMI.

Predictors of Inflammation in a Cohort of Bolivian Infants and Toddlers

Inflammation has been associated with cardiovascular disease and other health outcomes in children and adults, yet few longitudinal data are available on prevalence and predictors of inflammation in infants. We aimed to identify the prevalence of inflammation in a cohort of Bolivian infants and estimate its association with acute (recent illnesses) and chronic (overweight, stunting) morbidities and potential pathogen exposure (represented by water, sanitation, and hygiene [WASH] resources). We measured plasma concentrations of two acute phase proteins (C-reactive protein [CRP], marking acute inflammation, and alpha(1)-acid-glycoprotein [AGP], marking chronic inflammation) at three time points (target 2, 6-8, and 12-18 months). Of 451 singleton infants enrolled in the parent study, 272 had the first blood draw and complete data. Anthropometry and sociodemographic and recent illness data (2-week recall of cough, diarrhea, and fever) were collected at each visit. Inflammation was defined as CRP > 5 mg/L or AGP > 1 g/L. The prevalence of inflammation increased from early infancy (3% at first blood draw) to later infancy (15-22% at later blood draws). Recent cough, recent fever, and age in months were significantly associated with relative increases in CRP (7-44%) and AGP (5-23%), whereas recent diarrhea was only significantly associated with an increase in CRP (48%). Neither anthropometry nor WASH was significantly associated with inflammation. Results confirm the role of recent acute illness in inflammation in infants, and indicate that adiposity and WASH are not as important to inflammation in this age category.

The Effects of Season of Birth on the Inflammatory Response to Psychological Stress in Hainan Island, China

Season of birth (SOB) has been investigated as one of the environmental factors that might epigenetically determine the physiology of individuals. This study investigated the role of SOB in the association between Quality of Life (QOL), a proxy of psychological stress status, and C-reactive protein (CRP) concentration (i.e., inflammatory status) among 1,085 adults (aged 20–57 years old) in Hainan Island, China. High sensitivity CRP concentration was measured in dried blood spot samples, while the abbreviated version of the World Health Organization’s QOL questionnaire was used to gather information on six QOL domains. Analysis stratified by three historically distinct age groups revealed a significant association between CRP concentration, SOB, QOL and an interaction between SOB and QOL among the youngest and oldest groups. In the oldest group, those born in the dry season had a higher CRP concentration with worse QOL whereas in the youngest group, there was a higher CRP concentration with better QOL. Annual per capita rice production, a proxy of population nutritional status in the year of birth, was found to predict CRP concentration only among the second oldest group. These findings suggest that the early environment might affect the immune response to psychological stress in adulthood and that its effect may differ by the time period in which people were born.

Environmental, Dietary, and Behavioral Factors Distinguish Chinese Adults with High Waist-to-Height Ratio with and without Inflammation

BACKGROUND

The environmental and behavioral risk factors associated with central obesity and/or inflammation in populations exposed to both obesogenic and pathogenic environments remain unclear.

OBJECTIVES

We tested which of the characteristics distinguished 3 risk groups--high waist-to-height ratio (WHtR; >0.5) without inflammation [high-sensitivity C-reactive protein (hs-CRP) <3 mg/L], normal WHtR (≤ 0.5) with inflammation (hs-CRP: 3-10 mg/L), and high WHtR with inflammation--from the referent group with normal WHtR without inflammation and, secondarily, which factors differed between the groups with high WHtR with and without inflammation.

METHODS

The analytic sample included 8068 adults participating in the China Health and Nutrition Survey in 2009. Adjusted multinomial and logistic regression models were used to assess the risk of being in one of the "unhealthy" groups compared with the referent group.

RESULTS

Men with high WHtR with and without inflammation were more likely to live at higher urbanicity (57-63%) and have higher incomes (26-42%) and household sanitation (26-67%) and were >40% less likely to have high physical activity than the healthy referent group. Men with high WHtR with inflammation had higher odds of infectious symptoms than those with high WHtR without inflammation (OR: 1.73; 95% CI: 1.15, 2.61). Women with high WHtR without inflammation were less likely to have high household sanitation (44%) or perform high levels of physical activity (24%) and were 34% more likely to consume more fiber than the healthy referent group. Women with high WHtR and inflammation were more likely than those with high WHtR without inflammation to have infectious symptoms (OR: 1.45; 95% CI: 1.01, 2.07) and less likely to have higher fiber intake (OR: 0.77; 95% CI: 0.60,1.00) or physical activity (OR: 0.55; 95% CI: 0.41, 0.73).

CONCLUSION

These results document different underlying pathogenic and obesogenic risk factors for visceral adiposity with and without inflammation in Chinese adults, suggesting that context-specific approaches may be needed to prevent and treat inflammation.