Association of a polymorphism of BTN2A1 with chronic kidney disease in community-dwelling individuals

Distinct Gene Expression Profiles in Colonic Organoids from Normotensive and the Spontaneously Hypertensive Rats

Hypertension is associated with gut bacterial dysbiosis and gut pathology in animal models and people. Butyrate-producing gut bacteria are decreased in hypertension. RNA-seq analysis of gut colonic organoids prepared from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats was used to test the hypothesis that impaired interactions between the gut microbiome and gut epithelium are involved and that these would be remediated with butyrate supplementation. Gene expressions in immune responses including antigen presentation and antiviral pathways were decreased in the gut epithelium of the SHR in organoids and confirmed in vivo; these deficits were corrected by butyrate supplementation. Deficits in gene expression driving epithelial proliferation and differentiation were also observed in SHR. These findings highlight the importance of aligned interactions of the gut microbiome and gut immune responses to blood pressure homeostasis.

Prediction of Disordered Regions and Their Roles in the Anti-Pathogenic and Immunomodulatory Functions of Butyrophilins

Butyrophilins (BTNs) are a group of the moonlighting proteins, some members of which are secreted in milk. They constitute a large family of structurally similar type 1 transmembrane proteins from the immunoglobulin superfamily. Although the founding member of this family is related to lactation, participating in the secretion, formation and stabilization of milk fat globules, it may also have a cell surface receptor function. Generally, the BTN family members are known to modulate co-stimulatory responses, T cell selection, differentiation, and cell fate determination. Polymorphism of these genes was shown to be associated with the pathology of several human diseases. Despite their biological significance, structural information on human butyrophilins is rather limited. Based on their remarkable multifunctionality, butyrophilins seem to belong to the category of moonlighting proteins, which are known to contain intrinsically disordered protein regions (IDPRs). However, the disorder status of human BTNs was not systematically investigated as of yet. The goal of this study is to fill this gap and to evaluate peculiarities of intrinsic disorder predisposition of the members of human BTN family, and to find if they have IDPRs that can be attributed to the multifunctionality of these important proteins.

Butyrophilins: an important new element of resistance

Butyrophilins belonging to the immunoglobulin superfamily are new immune system regulators because they are present on lymphocytes, dendritic cells, monocytes, macrophages, neutrophils and eosinophils, and they exert a stimulatory and (or) inhibitory effect on them. The role of butyrophilins is associated and results from their similarity to the regulatory B7 protein family involved in the modulation of immune phenomena. Butyrophilins are glycoproteins built of two extracellular immunoglobulin domains, stabilized with disulfide bonds: constant IgC, and variable IgV and a transmembrane region. Most of these proteins contain a conserved domain encoded by a single exon – B30.2, also referred to as PRYSPRY. In humans, the family of butyrophilins includes 7 butyrophilin proteins, 5 butyrophilin-like proteins and the SKINT-like factor. Butyrophilins have been also demonstrated to play a role in various infections, e.g. tuberculosis or diseases that include sarcoidosis, systemic lupus erythematosus, rheumatoid arthritis, genetic metabolic diseases, ulcerative colitis, cancer and kidney disease.

Association of genetic variants with hypertension in a longitudinal population-based genetic epidemiological study

We previously identified 9 genes and chromosomal region 3q28 as susceptibility loci for Japanese patients with myocardial infarction, ischemic stroke, or chronic kidney disease by genome-wide or candidate gene association studies. In the present study, we investigated the possible association of 13 single nucleotide polymorphisms (SNPs) at these 10 loci with the prevalence of hypertension or their association with blood pressure (BP) in community-dwelling individuals in Japan. The study subjects comprised 6,027 individuals (2,250 subjects with essential hypertension, 3,777 controls) who were recruited into the Inabe Health and Longevity Study, a longitudinal genetic epidemiological study on atherosclerotic, cardiovascular and metabolic diseases. The subjects were recruited from individuals who visited the Health Care Center of Inabe General Hospital for an annual health checkup, and they are followed up each year (mean follow-up period, 5 years). Longitudinal analysis with a generalized estimating equation and with adjustment for age, gender, body mass index and smoking status revealed that rs2116519 of family with sequence similarity 78, member B (FAM78B; P=0.0266), rs6929846 of butyrophilin, subfamily 2, member A1 (BTN2A1; P= 0.0013), rs146021107 of pancreatic and duodenal homeobox 1 (PDX1; P=0.0031) and rs1671021 of lethal giant larvae homolog 2 (Drosophila) (LLGL2; P=0.0372) were significantly (P<0.05) associated with the prevalence of hypertension. Longitudinal analysis with a generalized linear mixed-effect model and with adjustment for age, gender, body mass index and smoking status among individuals not taking anti-hypertensive medication revealed that rs6929846 of BTN2A1 was significantly associated with systolic (P=0.0017), diastolic (P=0.0008) and mean (P=0.0005) BP, and that rs2116519 of FAM78B, rs146021107 of PDX1 and rs1671021 of LLGL2 were significantly associated with diastolic (P=0.0495), systolic (P=0.0132), and both diastolic (P=0.0468) and mean (0.0471) BP, respectively. BTN2A1 may thus be a susceptibility gene for hypertension.

Association of genetic variants with dyslipidemia and chronic kidney disease in a longitudinal population-based genetic epidemiological study

We previously identified 9 genes and chromosomal region 3q28 as susceptibility loci for myocardial infarction, ischemic stroke, or chronic kidney disease (CKD) in Japanese individuals by genome-wide or candidate gene association studies. In the present study, we examined the association of 13 polymorphisms at these 10 loci with the prevalence of hypertriglyceridemia, hyper-low-density lipoprotein (LDL) cholesterolemia, hypo-high-density lipoprotein (HDL) cholesterolemia, or CKD in community-dwelling Japanese individuals. The study subjects comprised 6,027 individuals who were recruited to the Inabe Health and Longevity Study, a longitudinal genetic epidemiological study of atherosclerotic, cardiovascular and metabolic diseases. The subjects were recruited from individuals who visited the Health Care Center at Inabe General Hospital for an annual health checkup, and they were followed up each year (mean follow‑up period, 5 years). Longitudinal analysis with a generalized estimating equation and with adjustment for covariates revealed that rs6929846 of butyrophilin, subfamily 2, member A1 gene (BTN2A1) was significantly associated with the prevalence of hypertriglyceridemia (P=0.0001), hyper-LDL cholesterolemia (P=0.0004), and CKD (P=0.0007); rs2569512 of interleukin enhancer binding factor 3 (ILF3) was associated with hyper-LDL cholesterolemia (P=0.0029); and rs2074379 (P=0.0019) and rs2074388 (P=0.0029) of alpha-kinase 1 (ALPK1) were associated with CKD. Longitudinal analysis with a generalized linear mixed-effect model and with adjustment for covariates among all individuals revealed that rs6929846 of BTN2A1 was significantly associated with the serum concentrations of triglycerides (P=0.0011), LDL cholesterol (P=3.3 x 10(-5)), and creatinine (P=0.0006), as well as with the estimated glomerular filtration rate (eGFR) (P=0.0004); rs2569512 of ILF3 was shown to be associated with the serum concentration of LDL cholesterol (P=0.0221); and rs2074379 (P=0.0302) and rs2074388 (P=0.0336) of ALPK1 were shown to be associated with the serum concentration of creatinine. Similar analysis among individuals not taking any anti‑dyslipidemic medication revealed that rs6929846 of BTN2A1 was significantly associated with the serum concentrations of triglycerides (P=8.3 x 10‑5) and LDL cholesterol (P=0.0004), and that rs2569512 of ILF3 was associated with the serum concentration of LDL cholesterol (P=0.0010). BTN2A1 may thus be a susceptibility gene for hypertriglyceridemia, hyper‑LDL cholesterolemia and CKD in Japanese individuals.

Association of genetic variants with coronary artery disease and ischemic stroke in a longitudinal population-based genetic epidemiological study

Our previous studies identified nine genes and chromosomal region 3q28 as susceptibility loci for myocardial infarction, ischemic stroke or chronic kidney disease by genome-wide or candidate gene association studies. As coronary artery disease (CAD) and ischemic stroke may share genetic architecture, certain genetic variants may confer susceptibility to the two diseases. The present study examined the association of 13 polymorphisms at these 10 loci with the prevalence of CAD or ischemic stroke in community-dwelling individuals, with the aim of identifying genetic variants that confer susceptibility to the two conditions. Study subjects (170 with CAD, 117 with ischemic stroke and 5,718 controls) were recruited to the Inabe Health and Longevity Study, a longitudinal genetic epidemiological study of atherosclerotic, cardiovascular and metabolic diseases. The subjects were recruited from individuals who visited for an annual health checkup and they were followed up each year (mean follow-up period, 5 years). Longitudinal analysis with a generalized estimating equation, and with adjustment for age, gender, body mass index, smoking status, the prevalence of hypertension, diabetes mellitus and dyslipidemia and the serum concentration of creatinine, revealed that rs2074380 (G→A) and rs2074381 (A→G) of the α-kinase 1 (ALPK1) gene and rs8089 (T→G) of the thrombospondin 2 (THBS2) gene were significantly (P<2×10^-16) associated with the prevalence of CAD, with the AA genotype of rs2074380 and GG genotypes of rs2074381 and rs8089 being protective against this condition. Similar analysis revealed that rs9846911 (A→G) at chromosome 3q28, rs2074381 of ALPK1, rs8089 of THBS2 and rs6046 (G→A) of the coagulation factor VII gene were significantly (P<2×10^-16) associated with the prevalence of ischemic stroke, with the GG genotypes of rs9846911, rs2074381 and rs8089 and the AA genotype of rs6046 being protective against this condition. ALPK1 and THBS2 may thus be susceptibility loci for CAD and ischemic stroke.

Association of genetic variants of the α-kinase 1 gene with type 2 diabetes mellitus in a longitudinal population-based genetic epidemiological study

Previously, our studies identified nine genes and the chromosomal region 3q28 as susceptibility loci for myocardial infarction, ischemic stroke or chronic kidney disease in individuals by genome-wide or candidate gene association studies. The present study examined the possible association of 13 polymorphisms at these 10 loci with the prevalence of type 2 diabetes mellitus (DM) in community-dwelling individuals. Study subjects comprised 6,027 individuals (797 subjects with type 2 DM and 5,230 controls) who were recruited to the Inabe Health and Longevity Study, a longitudinal genetic epidemiological study of atherosclerotic, cardiovascular and metabolic diseases. The subjects were recruited from individuals who visited for an annual health checkup and they were followed up each year (mean follow-up, 5 years). Longitudinal analysis with a generalized estimating equation and with adjustment for age, gender and body mass index (BMI) revealed that rs2116519 (C→T) of FAM78B (P=0.0188), as well as rs2074379 (G→A, P=0.0121) and rs2074388 (A→G, P=0.0053) of ALPK1 were significantly (P<0.05) associated with the prevalence of type 2 DM. Longitudinal analysis with a generalized linear mixed-effect model and with adjustment for age, gender and BMI among all the individuals revealed that rs2116519, rs2074379 and rs2074388 were significantly associated with fasting plasma glucose level (P=0.0352, 0.0017 and 0.0010, respectively) and to blood glycosylated hemoglobin (hemoglobin A_1c) content (P=0.0065, 0.0090 and 0.0079, respectively). Similar analysis among individuals not taking antidiabetic medication revealed that rs2074379 and rs2074388 were associated with the fasting plasma glucose level (P=0.0073 and 0.0042, respectively) and blood hemoglobin A_1c content (P=0.0142 and 0.0126, respectively), whereas rs2116519 was associated with blood hemoglobin A_1c content only (P=0.0470). ALPK1 may thus be a susceptibility gene for type 2 DM.