IgG is higher in South Asians than Europeans: does infection contribute to ethnic variation in cardiovascular disease?

N-glycan profiles of acute myocardial infarction patients reveal potential biomarkers for diagnosis, severity assessment, and treatment monitoring

Acute myocardial infarction (AMI) is a leading cause of mortality and morbidity worldwide. Diagnostic challenges remain in this highly time-sensitive condition. Using capillary electrophoresis-laser-induced fluorescence, we analyzed the blood plasma N-glycan profile in a cohort study comprising 103 patients with AMI and 69 controls. Subsequently, the data generated was subjected to classification modeling to identify potential AMI biomarkers. An area under the Receiving Operating Characteristic curve (AUCROC) of 0.81 was obtained when discriminating AMI versus non-MI patients. We postulate that the glycan profile involves a switch from a pro- to an anti-inflammatory state in the AMI pathophysiology. This was supported by significantly decreased levels in galactosylation, alongside increased levels in sialylation, afucosylation, and GlcNAc bisection levels in the blood plasma of AMI patients. By substantiating the glycomics analysis with immunoglobulin G (IgG) protein measurements, robustness of the glycan-based classifiers was demonstrated. Changes in AMI-related IgG activities were also confirmed to be associated with alterations at the glycosylation level. Additionally, a glycan-biomarker panel (GBP) derived from glycan features and current clinical biomarkers performed remarkably (AUCROC = 0.90, sensitivity = 0.579 at 5 percent false positive rate) when discriminating between patients with ST-segment elevation MI (n = 84) and non-ST-segment elevation MI (n = 19). Moreover, by applying the model trained using glycomics information, AMI and controls can still be discriminated at one and six months after baseline. Thus, glycomics biomarkers could potentially serve as a valuable complementary test to current diagnostic biomarkers. Additional research on their utility and associated biomechanisms via a large-scale study is recommended.

Ethnic differences in infectious burden and the association with metabolic risk factors for cardiovascular disease: a cross-sectional analysis

Background

The burden of metabolic risk factors for cardiovascular disease (CVD), such as type 2 diabetes, elevated cholesterol and hypertension, is unequally distributed across ethnic groups. Recent findings suggest an association of infectious burden (IB) and metabolic risk factors, but data from ethnic groups are scarce. Therefore, we investigated ethnic differences in IB and its association with metabolic risk factors.

Methods

We included 440 Dutch, 320 Turkish and 272 Moroccan participants, 18–70 years, of the 2004 general health survey in Amsterdam, the Netherlands. IB was defined by seropositivity to the sum of 6 infections: Herpes Simplex Virus 1 and 2; Hepatitis A, B and C; and Helicobacter pylori. Associations between IB categories 4–6 (high), 3 (intermediate) and 0–2 (low) infections and metabolic risk factors were assessed by logistic regression. Finally, we determined the contribution of IB to the association between ethnicity and the metabolic risk factors by comparing adjusted logistic regression models with and without IB categories.

Results

A high IB was more frequently observed among the Turkish and Moroccans than among the Dutch. After adjustment for age, sex, ethnicity, educational level, physical activity and body mass index, high IB was associated with type 2 diabetes (odds ratio high vs low IB (OR) =2.14, 95%-confidence interval (CI) 1.05–4.36). The association was weaker and not statistically significant, for elevated cholesterol (OR = 1.39, 95%-CI 0.82–2.34) and hypertension (OR = 1.49, 95%-CI 0.88–2.51). IB attenuated ethnic differences particularly for type 2 diabetes.

Conclusions

Our study showed that Turkish and Moroccan adults in Amsterdam have a higher IB than Dutch adults, which was associated with the differences in type 2 diabetes. Due to the cross-sectional nature of the study, we cannot draw a conclusions with regards to the time-sequence of cause and effect. Nevertheless, the findings ask for further research into the nature of association of IB with metabolic risk factors in a longitudinal setting.

Significantly lower anti-Leishmania IgG responses in Sudanese versus Indian visceral leishmaniasis

BACKGROUND

Visceral leishmaniasis (VL), a widely distributed systemic disease caused by infection with the Leishmania donovani complex (L. donovani and L. infantum), is almost always fatal if symptomatic and untreated. A rapid point-of-care diagnostic test for anti-Leishmania antibodies, the rK39-immunochromatographic test (rK39-ICT), has high sensitivity and specificity in South Asia but is less sensitive in East Africa. One of the underlying reasons may be continent-specific molecular diversity in the rK39 antigen within the L. donovani complex. However, a second reason may be differences in specific IgG anti-Leishmania levels in patients from different geographical regions, either due to variable antigenicity or immunological response.

METHODOLOGY/PRINCIPAL FINDINGS

We determined IgG titres of Indian and Sudanese VL patients against whole cell lysates of Indian and Sudanese L. donovani strains. Indian VL patients had significantly higher IgG titres against both L. donovani strains compared to Sudanese VL patients (p<0.0001). Mean reciprocal log10 50% end-point titres (1/log10t50) were i) 3.80 and 3.88 for Indian plasma and ii) 2.13 and 2.09 for Sudanese plasma against Indian and Sudanese antigen respectively (p<0.0001). Overall, the Indian VL patients therefore showed a 46.8-61.7 -fold higher mean ELISA titre than the Sudanese VL patients. The higher IgG titres occurred in children (<16 years old) and adults of either sex from India (mean 1/log10t50: 3.60-4.15) versus Sudan (mean 1/log10t50: 1.88-2.54). The greatest difference in IgG responses was between male Indian and Sudanese VL patients of ≥ 16 years old (mean 1/log10t50: 4.15 versus 1.99 = 144-fold (p<0.0001).

CONCLUSIONS/SIGNIFICANCE

Anti-Leishmania IgG responses among VL patients in Sudan were significantly lower than in India; this may be due to chronic malnutrition with Zn(2+) deficiency, or variable antigenicity and capacity to generate IgG responses to Leishmania antigens. Such differential anti-Leishmania IgG levels may contribute to lower sensitivity of the rK39-ICT in East Africa.

Opposing effects of pro- and anti-inflammatory cytokine gene polymorphisms on the risk for breast cancer in western Indian women: a pilot study

In an earlier study, the genotypes associated with higher level of transforming growth factor-β1 (TGF-β1) were found to reduce the risk for breast cancer in western Indian women. This observation implied that gene polymorphisms affecting the levels of pro- and anti-inflammatory cytokines may influence the risk for breast cancer in this population. Hence, we performed genotyping for three more functional single-nucleotide polymorphisms (SNPs) responsible for variations in the levels of cytokines associated with inflammation. To that effect, polymorphisms in genes coding for IL-4 (IL-4 C-590T; rs2243250), IFN-γ (IFN-G A + 874T; rs2430561) and MCP-1 (MCP-1 A-2578G; rs1024611) were examined in premenopausal, healthy women (N = 239) and patients with breast cancer (N = 182) from western India. In carriers of the IL-4*590T allele, a reduced risk for the disease (dominant model; OR = 0.61, 95% CI 0.37-0.98) was seen similar to that seen in TGF-B1*10C carriers. An opposite trend was observed with respect to the alleles associated with higher expression of MCP-1 or IFN-γ. In individuals positive for three or more alleles associated with higher levels of either pro- or anti-inflammatory cytokines, an additive effect on the modulation of risk for the disease was evident (for TGF-B1 & IL-4, OR = 0.33, 95% CI 0.12-0.87; for IFN-G & MCP-1, OR = 2.29, 95% CI 0.95-5.51). In the context of contrasting observations in other populations, these results indicate a significant contribution of anti-inflammatory genotypes in the modulation of risk for breast cancer in western Indian women.

Natural immune responses against eight oncogenic human papillomaviruses in the ASCUS-LSIL Triage Study

Only a subset of women with human papillomavirus (HPV) infections will become seropositive, and the factors influencing seroconversion are not well understood. We used a multiplex serology assay in women with mildly abnormal cytology results to examine seroreactivity to oncogenic HPV genotypes. An unbiased subset of women in the atypical squamous cell of undetermined significance /low-grade squamous intraepithelial lesion Triage Study provided blood samples at trial enrollment for serological testing. A Luminex assay based on glutathione s-transferase-L1 fusion proteins as antigens was used to test seroreactivity against eight carcinogenic HPV genotypes (16, 18, 31, 33, 35, 45, 52 and 58). We analyzed the relationship between seroprevalence in women free of precancer (N = 2,464) and HPV DNA status, age, sexual behavior and other HPV-related risk factors. The overall seroprevalence was 24.5% for HPV16 L1 and ∼20% for 18L1 and 31L1. Among women free of precancer, seroprevalence peaked in women less than 29 years and decreased with age. Type-specific seroprevalence was associated with baseline DNA detection for HPV16 (OR = 1.36, 95%CI: 1.04-1.79) and HPV18 (OR = 2.31, 95%CI: 1.61-3.32), as well as for HPV52 and HPV58. Correlates of sexual exposure were associated with increased seroprevalence across most genotypes. Women who were current or former smokers were less likely to be seropositive for all eight of the tested oncogenic genotypes. The multiplex assay showed associations between seroprevalence and known risk factors for HPV infection across nearly all tested HPV genotypes but associations between DNA- and serostatus were weak, suggesting possible misclassification of the participants' HPV serostatus.

Transforming growth factor β signaling pathway associated gene polymorphisms may explain lower breast cancer risk in western Indian women

Transforming growth factor β1 (TGFB1) T29C and TGF β receptor type 1 (TGFBR1) 6A/9A polymorphisms have been implicated in the modulation of risk for breast cancer in Caucasian women. We analyzed these polymorphisms and combinations of their genotypes, in pre menopausal breast cancer patients (N = 182) and healthy women (N = 236) from western India as well as in breast cancer patients and healthy women from the Parsi community (N = 48 & 171, respectively). Western Indian women were characterized by a higher frequency of TGFB1*C allele of the TGF β T29C polymorphism (0.48 vs 0.44) and a significantly lower frequency of TGFBR1*6A allele of the TGFBR1 6A/9A polymorphism (0.02 vs 0.068, p<0.01) as compared to healthy Parsi women. A strong protective effect of TGFB1*29C allele was seen in younger western Indian women (<40 yrs; OR = 0.45, 95% CI 0.25-0.81). Compared to healthy women, the strikingly higher frequencies of low or intermediate TGF β signalers in patients suggested a strong influence of the combination of these genotypes on the risk for breast cancer in Parsi women (for intermediate signalers, OR = 4.47 95%CI 1.01-19.69). The frequency of low signalers in Parsi healthy women, while comparable to that reported in Europeans and Americans, was three times higher than that in healthy women from western India (10.6% vs 3.3%, p<0.01). These observations, in conjunction with the low incidence rate of breast cancer in Indian women compared to White women, raise a possibility that the higher frequency of TGFB1*29C allele and lower frequency of TGFBR1*6A allele may represent important genetic determinants that together contribute to a lower risk of breast cancer in western Indian women.

Vascular risk factors in South Asians

South Asians originate from the Indian sub-continent (India, Pakistan, Bangladesh, Sri Lanka and Nepal) and represent one fifth of the world's population. Several studies suggested that South Asians have an increased risk of developing coronary heart disease (CHD) when compared with European populations. We review the role of traditional and emerging risk factors in the increased CHD risk in South Asians. The high prevalence of insulin resistance and type 2 diabetes mellitus in South Asians may be a major cause for their elevated vascular risk. However, other established and emerging risk factors are also overrepresented in South Asians. Large-scale prospective studies could determine the relative contribution of established and emerging vascular risk factors in South Asians. There is an urgent need for trials in South Asians that will evaluate clinical outcomes following treatment of these risk factors.

Ethnic variations in the management of patients with acute stroke

BACKGROUND

There is increasing interest in the management of stroke in ethnic minorities but few studies have considered this issue. This study investigated if differences in acute stroke management exist between a white European and Bangladeshi populations living in London, England.

METHODS

All stroke surviving patients discharged over a five year period in a major London teaching hospital based in an ethnically diverse area of inner city London were recruited. Cerebrovascular risk factors, their management, and investigation for acute stroke syndromes were recorded and comparison between white and Bangladeshi cohorts was made. Categorical data were analysed using Fisher's exact test.

RESULTS

Measurement of cholesterol concentrations are undertaken less often in those from a Bangladeshi background (25%) compared with white Europeans (76%) (p<0.0001). Statin therapy tends to be given less often to Bangladeshis. However, neuroimaging (p<0.05) and echocardiography (p<0.0001) is performed more often in Bangladeshis compared with white Europeans.

CONCLUSION

There are variations in the management of acute stroke because of ethnicity and these variations could have substantial consequences on secondary rates of cerebrovascular and cardiovascular disease. Whether the reasons for this disparity are attributable to inequity or iniquity of care need to be further investigated perhaps along with the development of ethnicity specific protocols. Overall the management of stroke and its risk factors in either racial group remains lamentable.

Ethnicity, infection and sudden infant death syndrome

Epidemiological studies found the incidence of SIDS among Indigenous groups such as Aboriginal Australians, New Zealand Maoris and Native Americans were significantly higher than those for non-Indigenous groups within the same countries. Among other groups such as Asian families in Britain, the incidence of SIDS has been lower than among groups of European origin. Cultural and childrearing practices as well as socio-economic factors have been proposed to explain the greater risk of SIDS among Indigenous peoples; however, there are no definitive data to account for the differences observed. We addressed the differences among ethnic groups in relation to susceptibility to infection because there is evidence from studies of populations of European origin that infectious agents, particularly toxigenic bacteria might trigger the events leading to SIDS. The risk factors for SIDS parallel those for susceptibility to infections in infants, particularly respiratory tract infections which are also major health problems among Indigenous groups. Many of the risk factors identified in epidemiological studies of SIDS could affect three stages in the infectious process: (1) frequency or density of colonisation by the toxigenic species implicated in SIDS; (2) induction of temperature-sensitive toxins; (3) modulation of the inflammatory responses to infection or toxins. In this review we compare genetic, developmental and environmental risk factors for SIDS in ethnic groups with different incidences of SIDS: low (Asians in Britain); moderate (European/Caucasian); high (Aboriginal Australian). Our findings indicate: (1) the major difference was high levels of exposure to cigarette smoke among infants in the high risk groups; (2) cigarette smoke significantly reduced the anti-inflammatory cytokine interleukin-10 responses which control pro-inflammatory responses implicated in SIDS; (3) the most significant effect of cigarette smoke on reduction of IL-10 responses was observed for donors with a single nucleotide polymorphism for the IL-10 gene that is predominant among both Asian and Aboriginal populations. If genetic makeup were a major factor for susceptibility to SIDS, the incidence of these deaths should be similar for both populations. They are, however, significantly different and most likely reflect differences in maternal smoking which could affect frequency and density of colonisation of infants by potentially pathogenic bacteria and induction and control of inflammatory responses.

Serological evidence of Helicobacter pylori infection in UK South Asian and European populations: implications for gastric cancer and coronary heart disease

OBJECTIVES

To describe the prevalence of serological evidence of infection with Helicobacter pylori among people of South Asian and European ethnic origins and to assess its association with prevalent coronary heart disease (CHD).

METHODS

We used a quantitative method to compare IgG antibodies to H. pylori in a population sample of 300 South Asians and 302 Europeans in Newcastle upon Tyne, UK.

RESULTS

For men and women, respectively, H. pylori IgG (95% confidence interval) was 16.7 microg/ml (13.9, 20.2) and 11.3 (9.4, 13.5) among Europeans and 11.6 (9.8, 13.7) and 14.3 (12.1, 16.9) among South Asians. Levels were higher in older participants and in those of lower socioeconomic status. The ratio of geometric mean IgG, (95% confidence interval) adjusted for age, sex and socioeconomic status, in those with and without CHD was 1.02 (0.49, 2.11) among Europeans and 1.79 (1.01, 3.17) among South Asians. Antibodies against staphylococcal enterotoxins A and B were higher among South Asians than Europeans.

CONCLUSIONS

The prevalence of H. pylori infection among UK South Asians does not reflect that of their countries of origin, nor their lower prevalence of gastric cancer. The association with CHD in South Asians requires corroboration in other studies.