Single nucleotide polymorphisms of ADRB2 gene and their association with susceptibility for Plasmodium falciparum malaria and asthma in an Indian population

Diagnosis of cerebral malaria: Tools to reduce Plasmodium falciparum associated mortality

Cerebral malaria (CM) is a major cause of mortality in Plasmodium falciparum (Pf) infection and is associated with the sequestration of parasitised erythrocytes in the microvasculature of the host's vital organs. Prompt diagnosis and treatment are key to a positive outcome in CM. However, current diagnostic tools remain inadequate to assess the degree of brain dysfunction associated with CM before the window for effective treatment closes. Several host and parasite factor-based biomarkers have been suggested as rapid diagnostic tools with potential for early CM diagnosis, however, no specific biomarker signature has been validated. Here, we provide an updated review on promising CM biomarker candidates and evaluate their applicability as point-of-care tools in malaria-endemic areas.

Malaria Epidemiology and COVID-19 Pandemic: Are They Interrelated?

Coronavirus disease 2019 (COVID-19) is a systemic disease, impacting multiple organs in the human body. But COVID-19 also impacts other diseases of relevance to public and planetary health. To understand and respond to the COVID-19 pandemic, we need an intersectional conceptual lens and systems thinking. For example, the strain on health care systems due to COVID-19 has adversely impacted global malaria elimination programs. With many epidemiological, clinical, and biological parallels documented, we examined in this study the scenario of malaria and COVID-19 syndemic in India. The disruptive influence of COVID-19 on the National Framework for Malaria Elimination (NFME), impact of unintended chemoprophylaxis, population genetic influences, and the shifting patterns of epidemiology are compared. Importantly, a time series analysis forecasted the burden of malaria increasing in the upcoming years. Although reported malaria cases showed a decline in 2020 compared to the previous years, an increase in cases was documented in 2021, with nine states reporting an increase up to July 2021. Pandemics often cause crosscutting disruptions in health care. Reshaping the priorities of the malaria elimination program and a diligent implementation of the priorities in the NFME would, therefore, be well-advised: (1) vector control, (2) antimalarial therapy recommendations, (3) monitoring drug resistance, (4) prevention of the spread of asymptomatic disease-causing low-density transmission, and (5) large-scale testing measures. In conclusion, the findings from the present study inform future comparative studies in other world regions to better understand the broader, systemic, temporal, and spatial impacts of the COVID-19 pandemic on existing and future diseases across public health systems and services.

Erythrocyte miRNA regulators and malarial pathophysiology

Pathophysiology of Plasmodium falciparum and Plasmodium vivax in malaria vis a vis host and the parasite genome interactions has been deciphered recently to present the biology of cerebral malaria, severe anaemia and placental malaria. Small non-coding RNAs have exhibited their potential to be considered as indicators and regulators of diseases. The malarial pathologies and their associated mechanisms mediated by miRNAs and their role in haematopoiesis and red cell-related disorders are elucidated. Evidence of miRNA carrying exosome-like vesicles released during infection, delivering signals to endothelial cells enhancing gene expression, resulting in parasite sequestration and complications leading to pathologies of cerebral malaria are important breakthroughs. Pregnancy malaria showed Plasmodium surface antigen promoted erythrocyte sequestration in the placental intervillous space, provoking disease development and assorted complications. Syncytiotrophoblast-derived microparticles during pregnancy and fetus development may predict pathophysiological progression on account of their altered miRNA cargoes in malaria.

Genetic variability of five ADRB2 polymorphisms among Mexican Amerindian ethnicities and the Mestizo population

The Mexican population is characterized by high and particular admixture, and the picture of variants associated with disease remains unclear. Here we investigated the distribution of single nucleotide polymorphisms (SNPs) in the Mexican population. We focused on two non-synonymous and three synonymous SNPs in the beta-2 adrenergic receptor gene (ADRB2), which plays key roles in energy balance regulation. These SNPs were genotyped in 2,011 Mexican Amerindians (MAs) belonging to 62 ethnic groups and in 1,980 geographically matched Mexican Mestizos (MEZs). The frequency distribution of all five ADRB2 variants significantly differed between MAs, MEZs, and other continental populations (CPs) from the 1000 Genomes database. Allele frequencies of the three synonymous SNPs rs1042717A, rs1042718A, and rs1042719C were significantly higher in Mexican individuals, particularly among MAs, compared to in the other analyzed populations (P<0.05). The non-synonymous ADRB2 Glu27 allele (rs1042714G), which is associated with several common conditions, showed the lowest frequency in MAs (0.03) compared to other populations worldwide. Among MEZs, this allele showed a frequency of 0.15, intermediate between that in MAs and in Iberians (0.43). Moreover, Glu27 was the only SNP exhibiting a geographic gradient within the MEZ population (from 0.22 to 0.11), reflecting admixed mestizo ancestry across the country. Population differentiation analysis demonstrated that Glu27 had the highest F_ST value in MAs compared with Europeans (CEU) (0.71), and the lowest between MAs and Japanese (JPT) (0.01), even lower than that observed between MAs and MEZs (0.08). This analysis demonstrated the genetic diversity among Amerindian ethnicities, with the most extreme F_ST value (0.34) found between the Nahuatls from Morelos and the Seris. This is the first study of ADRB2 genetic variants among MA ethnicities. Our findings add to our understanding of the genetic contribution to variability in disease susceptibility in admixed populations.

Association of β2-adrenergic receptor gene polymorphisms (rs1042713, rs1042714, rs1042711) with asthma risk: a systematic review and updated meta-analysis

Background

The published data on the association between β2-adrenergic receptor gene polymorphisms and asthma susceptibility are inconclusive. To derive a more precise estimation of this association, a meta-analysis was performed.

Methods

A literature search was conducted in PubMed, Web of Science, EMBASE, Wanfang, and the China National Knowledge Infrastructure (CNKI) databases to identify eligible studies. The pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to calculate the strength of the association. A sensitivity analysis was performed to evaluate the influence of individual studies on the overall effect estimates, and funnel plots and Egger’s tests were used for indications of publication bias.

Results

Seventy three studies with three single nucleotide polymorphisms (SNP) (rs1042713, c.G46A, p.Gly16Arg; rs1042714, c.G79C, p.Gln27Glu; rs1042711, c.T-47C, p.Cys19Arg) were finally identified. For the rs1042713 polymorphism, no significant association with asthma risk was found in the overall population. However, a significant protective association was found in the Indian population in the dominant model comparison (OR = 0.72, 95% CI = 0.59–0.87, I² = 25%, studies = 5, cases = 1190, controls = 1241). A significant risk association was found in the Arab population in the dominant model comparison (OR = 1.75, 95% CI = 1.14–2.70, I² = 0%, studies = 2, cases = 307, controls = 361) and the homozygote model comparison (OR = 1.88, 95% CI = 1.17–3.02, I² = 0%, studies = 2, cases = 307, controls = 361), and in the Hispanic-Latino population in the dominant model comparison (OR = 1.68, 95% CI = 1.10–2.55, I² = 77%, studies = 5, cases = 1026, controls = 1412). For the rs1042714 polymorphism, we found a significant association in the recessive model comparison (OR = 0.83, 95% CI = 0.70–0.98, I² = 44%, studies = 52, cases = 8242, controls = 16,832), the homozygote genotype comparison (OR = 0.84, 95% CI = 0.72–0.98, I² = 25%, studies = 52, cases = 8242, controls = 16,832) and the allelic genetic model (OR = 0.91, 95% CI = 0.83–0.99, I² = 59%, studies = 52, cases = 8242, controls = 16,832) in the overall population. When stratified by age, a significant association was also found in children in the recessive model comparison (OR = 0.59, 95% CI = 0.39–0.88, I² = 58%, studies = 18, cases = 2498, controls = 2510) and the homozygote genotype comparison (OR = 0.63, 95% CI = 0.43–0.92, I² = 46%, studies = 18, cases = 2498, controls = 2510), but not in adult. For the rs1042711 polymorphism, no significant associations were found in the any genetic model.

Conclusion

The meta-analysis suggests that the ADRB2 rs1042714 polymorphism has a protective association with asthma in the overall population and the pediatric subgroup.

Mouse NC/Jic strain provides novel insights into host genetic factors for malaria research

Malaria is caused by Plasmodium parasites and is one of the most life-threatening infectious diseases in humans. Infection can result in severe complications such as cerebral malaria, acute lung injury/acute respiratory distress syndrome, and acute renal injury. These complications are mainly caused by P. falciparum infection and are major causes of death associated with malaria. There are a few species of rodent-infective malaria parasites, and mice infected with such parasites are now widely used for screening candidate drugs and vaccines and for studying host immune responses and pathogenesis associated with disease-related complications. We found that mice of the NC/Jic strain infected with rodent malarial parasites exhibit distinctive disease-related complications such as cerebral malaria and nephrotic syndrome, in addition to a rapid increase in parasitemia. Here, we focus on the analysis of host genetic factors that affect malarial pathogenesis and describe the characteristic features, utility, and future prospects for exploitation of the NC/Jic strain as a novel mouse model for malaria research.

Beta2-Adrenergic Receptor Polymorphisms and Haplotypes Associate With Chronic Pain in Sickle Cell Disease

Pain in sickle cell disease (SCD) is severe, variable, and inadequately comprehended. The β2-adrenergic receptor (ADRB2) is critical in mediating neurotransmitter response in the sympathetic nervous system. In this association study, we examined 16 single nucleotide polymorphisms (SNPs) covering 5'-UTR and coding regions of ADRB2 for pain variability in SCD. Subjects recorded their non-crisis, baseline pain experience on a computerized tool from which we obtained chronic pain measurement score- composite pain index (CPI). Regression models yielded significant associations between chronic pain and seven SNPs. Non-synonymous SNP rs1042713 A allele (Arg16) caused a 5.73-fold decrease in CPI (p = 0.002). Allele A of rs12654778 and T of rs17778257 reduced CPI by a fold of 4.52 (p = 0.019), and 4.39 (p = 0.032), respectively. Whereas, in the 5' UTR, allele C of rs1042711, G of rs11168070, C of rs11959427, and C of rs1801704 increased CPI by a fold of 10.86 (p = 0.00049), 5.99 (p = 0.016), 5.69 (p = 0.023), and 5.26 (p = 0.031), respectively. Together, these SNPs accounted for 2-15% of CPI variance after adjusting for covariates. Moreover, these SNPs were in high linkage disequilibrium (LD) showing three LD blocks in our cohort. A 10-marker haplotype increased CPI by 11.5-fold (p = 0.000407). Thus, ADRB2 polymorphisms might contribute to chronic pain severity and heterogeneity in SCD.

Association Between ADRB2 Genetic Polymorphisms and the Risk of Chronic Obstructive Pulmonary Disease: A Case-Control Study in a Chinese Population

OBJECTIVE

This study was designed to investigate the association between single nucleotide polymorphisms (SNPs) of the β2-adrenergic receptor (ADRB2) gene and the risk of chronic obstructive pulmonary disease (COPD) in a Chinese population.

METHODS

From January 2010 to October 2014, 261 COPD patients were selected as the case group and 239 healthy subjects were selected as the control group. Pulmonary function tests were performed to detect forced vital capacity (FVC), 1-s forced expiratory volume (FEV₁), and FEV₁/FVC (%). rs1042711, rs1042714, and rs1042718 were selected as tagSNPs of the ADRB2 gene from the HapMap database in accordance with previous studies. The ADRB2 genotypes were established by real-time polymerase chain reaction assays using TaqMan-labeled probes. The relationships between the ADRB2 polymorphisms and COPD risk were estimated using logistic regression analyses.

RESULTS

The frequency of the genotypes and alleles of rs1042711 in ADRB2 showed a significant difference between the COPD and control groups (p < 0.05); compared with the CC genotype, the non-CC genotypes showed an increased COPD risk (p = 0.002). Compared with the CC haplotype, the TG haplotype increased COPD risk, while the CG haplotype reduced COPD risk for normal individuals. Compared with the CC genotype, the TT genotype showed significantly lower FEV₁ and FEV₁/FVC (p = 0.022, p = 0.0191, respectively). Both the TC and TG haplotypes showed lower FEV₁ and FEV₁/FVC in comparison with the CC haplotype (both p < 0.05). The results of logistic regression analysis showed that rs1042711 of ADRB2 and smoking history were associated with COPD risk (both p < 0.05).

CONCLUSION

It is indicated that the TT genotype of rs1042711 and smoking pack years are both risk factors for COPD.

Overview of human genetic susceptibility to malaria: From parasitemia control to severe disease

Malaria is a life-threatening blood disease caused by the protozoan Plasmodium. Infection may lead to several different patterns of symptoms in the host: asymptomatic state, uncomplicated disease or severe disease. Severe malaria occurs mostly in young children and is a major cause of death. Disease is thought to result from the sequestration of parasites in the small blood vessels of the brain and the deregulation of key immune system elements. The cellular and molecular regulatory mechanisms underlying the pathogenesis of disease are however not fully understood. What is known it is that the genetic determinants of the host play an important role in the severity of the disease and the outcome of infection. Here we review the most convincing results obtained through genetic epidemiology studies concerning the genetic control of malaria in human caused by Plasmodium falciparum infection. The identification of genes conferring susceptibility or resistance to malaria might improve diagnosis and treatment.

ADRB2 polymorphisms in allergic asthma in Han Chinese children

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in the human β2 adrenergic receptor (ADRB2) gene have been linked to pathogenesis of and treatment responses in asthma. In China, where asthma is common, little information exists regarding ADRB2 variants and their effects on asthma. The current study sought to investigate the relationship between variations in ADRB2 and childhood asthma.

METHODS

Blood samples were collected from 298 pediatric asthma cases treated in our hospital from July 2013 to September 2014; 304 samples were collected from healthy children for a control group. Six loci (at base positions -47, 79, -2387, 46, 523, and 491) of ADRB2 were genotyped using the TaqMan probe assay; SHEsis was used to determine haplotypes. Allele frequencies and genotype distributions were compared between groups using chi square and t tests.

RESULTS

No significant differences in genotype or allele frequencies were found between the groups for the polymorphic loci -2387 bp (T>C), 46 bp (G>A), and 523 bp (C>A) (p > 0.05). However, genotype frequencies for the ADRB2 SNPs at -47 bp (C>T) and 79 bp (G>C) differed significantly between asthma and control groups (p < 0.05). Further, linkage disequilibrium was found between these 2 SNPs (D' = 0.990, r(2) = 0.962), as well as between SNPs at 46 and 523 bp (D' = 0.985, r(2) = 0.607). Finally, of the 4 haplotypes analyzed in these samples (haplotypes III, IV, IX, and XI), the frequency of haplotype III was significantly lower in the asthma group than the control group (p < 0.05; odds ratio [OR] = 0.72; 95% confidence interval [CI], 0.48 to 0.97).

CONCLUSION

Variations of ADRB2 at base positions -47 (C>T) and 79 (G>C), as well as haplotype III, may contribute to susceptibility to childhood asthma.

Categorical complexities of Plasmodium falciparum malaria in individuals is associated with genetic variations in ADORA2A and GRK5 genes

In the erythrocytes, malaria parasite entry and infection is mediated through complex membrane sorting and signaling processes. We investigated the effects of single-locus and multilocus interactions to test the hypothesis that the members of the GPCR family genes, adenosine A2a receptor (ADORA2A) and G-protein coupled receptor kinase5 (GRK5), may contribute to the pathogenesis of malaria caused by Plasmodium falciparum (Pf) independently or through complex interactions. In a case-control study of adults, individuals affected by Pf malaria (complicated n=168; uncomplicated n=282) and healthy controls (n=450) were tested for their association to four known SNPs in GRK5 (rs2230345, rs2275036, rs4752307 and rs11198918) and two in ADORA2A (rs9624472 and rs5751876) genes with malaria susceptibility, using techniques of polymerase chain reaction-restriction fragment length polymorphisms and direct DNA sequencing. Single-locus analysis showed significant association of 2 SNPs; rs5751876 (OR=3.2(2.0-5.2); p=0.0006) of ADORA2A and rs2230345 (OR=0.3(0.2-0.5); p=0.0006) of GRK5 with malaria. The mean of the serum creatinine levels were significantly higher in patients with variant GG (p=0.006) of rs9624472 in ADORA2A gene compared to AA and AG genotypes in complicated Pf malaria cases, with the G allele also showing increased risk for malaria (OR=1.3(1.1-1.6); p=0.017). Analyses of predicted haplotypes of the two ADORA2A and the four GRK5 SNPs have identified the haplotypes that conferred risk as well as resistance to malaria with statistical significance. Molecular docking analysis of evolutionary rs2230345 SNP indicated a stable activity of GRK5 for the mutant allele compared to the wild type. Further, generalized multifactor dimensionality reduction to test the contribution of individual effects of the six polymorphisms and higher-order interactions to risk of symptoms/clinical complications of malaria suggested a best six-locus model showing statistical significance. The study provides evidence for the role of ADORA2A and GRK5 that might influence the etiology of malaria infection.

Potential Signal Transduction Regulation by HDL of the β2-Adrenergic Receptor Pathway. Implications in Selected Pathological Situations

The main atheroprotective mechanism of high-density lipoprotein (HDL) has been regarded as reverse cholesterol transport, whereby cholesterol from peripheral tissues is removed and transported to the liver for elimination. Although numerous additional atheroprotective mechanisms have been suggested, the role of HDL in modulating signal transduction of cell membrane-bound receptors has received little attention to date. This potential was recently highlighted following the identification of a polymorphism in the adenylyl cyclase 9 gene (ADCY9) that was shown to be a determining factor in the risk of cardiovascular (CV) events in patients treated with the HDL-raising compound dalcetrapib. Indeed, ADCY9 is part of the signaling pathway of the β2-adrenergic receptor (β2-AR) and both are membrane-bound proteins affected by changes in membrane-rich cholesterol plasma membrane domains (caveolae). Numerous G-protein-coupled receptors (GPCRs) and ion channels are affected by caveolae, with caveolae composition acting as a 'signalosome'. Polymorphisms in the genes encoding ADCY9 and β2-AR are associated with response to β2-agonist drugs in patients with asthma, malaria and with sickle cell disease. Crystallization of the β2-AR has found cholesterol tightly bound to transmembrane structures of the receptor. Cholesterol has also been shown to modulate the activity of this receptor. Apolipoprotein A1 (ApoA1), the major protein component of HDL, destabilizes and removes cholesterol from caveolae with high affinity through interaction with ATP-binding cassette transporter. Furthermore, β2-AR activity may be affected by ApoA1/HDL-targeted therapies. Taken together, these observations suggest a common pathway that potentially links a primary HDL function to the regulation of signal transduction.

Association between β2-adrenoceptor gene polymorphisms and asthma risk: an updated meta-analysis

Background

Evidence is increasingly accumulated about multiple roles for the β2-adrenoceptor gene in asthma. The results were inconsistent partly due to small sample sizes. To assess the association between β2-adrenoceptor gene polymorphisms and asthma risk, a meta-analysis was performed.

Methods

We comprehensively searched the PubMed, EMBASE, BIOSIS Previews databases and extracted data from all eligible articles to estimate the association between β2-adrenoceptor gene polymorphisms and asthma risk. The pooled odds ratio (OR) with 95% confidence intervals (CIs) were calculated.

Results

Thirty-seven studies involving 6648 asthma patients and 15943 controls were included in the meta-analysis. Overall, significant associations were found in allelic genetic model (OR = 1.06, 95% CI = 1.01∼1.12), recessive genetic model (OR = 1.11, 95% CI = 1.02∼1.21) for Arg/Gly16. Stratified by ethnicity and age, significant associations were also found in Asian population in allelic genetic model, recessive genetic model and addictive model. For Gln/Glu27, no significant association was found when we combined all eligible studies. Age stratification showed significant associations in adults in allelic genetic model and recessive genetic model, but no significant association was found among Asians and Caucasians in ethnicity stratification.

Conclusions

This meta-analysis implied that the β2-adrenoceptor Arg/Gly16 polymorphism was likely to contribute to asthma risk in Asian population. Gln/Glu27 polymorphism might be a contributor to asthma susceptibility for adults.