Polymorphism of the uteroglobin gene in systemic lupus erythematosus and IgA nephropathy

Surface Nanosieving Polyether Sulfone Particles with Graphene Oxide Encapsulation for the Negative Isolation toward Extracellular Vesicles

Extracellular vesicles (EVs) contain specific biomarkers for disease diagnosis. Current EV isolation methods are hampered in important biological applications due to their low recovery and purity. Herein, we first present a novel EV negative isolation strategy based on surface nanosieving polyether sulfone particles with graphene oxide encapsulation (SNAPs) by which the coexisting proteins are irreversibly adsorbed by graphene oxide (GO) inside the particles, while EVs with large sizes are excluded from the outside due to the well-defined surface pore sizes (10-40 nm). By this method, the purity of the isolated EVs from urine could be achieved 4.91 ± 1.01e¹⁰ particles/μg, 40.9-234 times higher than those obtained by the ultracentrifugation (UC), size-exclusion chromatography (SEC), and PEG-based precipitation. In addition, recovery ranging from 90.4 to 93.8% could be obtained with excellent reproducibility (RSD < 6%). This was 1.8-4.3 times higher than those obtained via SEC and UC, comparable to that obtained by PEG-based precipitation. Taking advantage of this strategy, we further isolated urinary EVs from IgA nephropathy (IgAN) patients and healthy donors for comparative proteome analysis, by which significantly regulated EV proteins were found to distinguish IgAN patients from healthy donors. All of the results indicated that our strategy would provide a new avenue for highly efficient EV isolation to enable many important clinical applications.

Uteroglobin gene polymorphism (G38A) may be a risk factor in childhood idiopathic nephrotic syndrome

BACKGROUND

Uteroglobin (UG) is a multifunctional protein with anti-inflammatory properties. The aim of this study was to first evaluate the role of UG gene G38A polymorphism in childhood idiopathic nephrotic syndrome (INS), and determine whether this variation may be related to the occurrence of INS or a steroid response.

METHODS

One hundred and thirty-six children diagnosed with INS in Gaziantep University, Department of Pediatric Nephrology, and 70 healthy volunteers were included. Children with INS were divided into two groups: steroid-sensitive (n = 84), and steroid-resistant (n = 52). Samples were examined using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) enzyme method.

RESULTS

The distributions of AA, GG, and AG genotypes of UG gene G38A (G/A) were 16.9%, 44.9%, and 38.2% in the all-INS group, whereas they were 14.3%, 48.8%, and 36.9% in the steroid-sensitive INS (SSINS) group compared with 21.1%, 38.5%, and 40.4% in steroid-resistant INS (SRINS), and 5.7%, 41.4%, and 52.9% in controls. The risk of INS was increased almost 4-fold in children with the AA genotype (p = 0.016). The risk of having SSINS was increased 3.5-fold (p = 0.042) whereas the risk of SRINS was increased 4.8-fold in the same genotype (p = 0.014).

CONCLUSIONS

The uteroglobin gene may play an important role in the development of INS, and the AA genotype of UG gene G38A polymorphism was found more frequently in those children. Further studies evaluating all polymorphisms in larger patient groups are needed to exactly determine the effect of UG gene on the development of INS and steroid response in children.

CCSP G38A polymorphism environment interactions regulate CCSP levels differentially in COPD

Impaired airway homeostasis in chronic obstructive pulmonary disease (COPD) could be partly related to club cell secretory protein (CCSP) deficiency. We hypothesize that CCSP G38A polymorphism is involved and aim to examine the influence of the CCSP G38A polymorphism on CCSP transcription levels and its regulatory mechanisms. CCSP genotype and CCSP levels in serum and sputum were assessed in 66 subjects with stable COPD included in a 1-yr observational study. Forty-nine of them had an exacerbation. In an in vitro study, the impact on the CCSP promoter of 38G wild-type or 38A variant was assessed. BEAS-2B cells were transfected by either the 38G or 38A construct, in the presence/absence of cigarette smoke extract (CSE) or lipopolysaccharides (LPS). Cotransfections with modulating transcription factors, p53 and Nkx2.1, identified by in silico analysis by using ConSite and TFSEARCH were conducted. A allele carrier COPD patients had lower serum and sputum CCSP levels, especially among active smokers, and a decreased body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) score. In vitro, baseline CCSP transcription levels were similar between the wild and variant constructs. CSE decreased more profoundly the CCSP transcription level of 38A transfected cells. The opposite effect was observed with p53 cotransfection. LPS stimulation induced CCSP repression in 38A promoter transfected cells. Cotransfection with Nkx2.1 significantly activated the CCSP promoters irrespective of the polymorphism. Circulating CCSP levels are associated with smoking and the CCSP G38A polymorphism. CSE, LPS, and the Nkx2.1 and p53 transcription factors modulated the CCSP promoter efficiency. The 38A polymorphism exaggerated the CCSP repression in response to p53 and CSE.

Association of uteroglobin G38A gene polymorphism with IgA nephropathy risk: an updated meta-analysis

Association of uteroglobin G38A gene polymorphism and IgA nephropathy (IgAN) risk is still not clear. This investigation was conducted to assess if there was an association between the uteroglobin G38A gene polymorphism and IgAN risk using meta-analysis. The relevant literatures were identified from PubMed, and Cochrane Library on 10 October 2013, and eligible studies were included and synthesized. Seven reports were recruited into this meta-analysis for the association of the uteroglobin G38A gene polymorphism with IgAN risk. In overall population, the A allele and AA genotype were not associated with IgAN risk. Furthermore, the GG genotype was also not associated with IgAN risk in overall population. Interestingly, the association of uteroglobin G38A gene polymorphism with IgAN risk was also not found in Asians and in Caucasians. In the sensitivity analysis, according to Hardy-Weinberg equilibrium test, according to the control source from healthy, the genotyping methods using PCR-RFLP, PCR-SSCP, no association of the uteroglobin G38A gene polymorphism with IgAN risk was found and the results were similar to those in non-sensitivity analysis. In conclusion, the uteroglobin G38A gene polymorphism was not associated with IgAN risk. However, additional studies are required to firmly establish a correlation between the uteroglobin G38A gene polymorphism and IgAN risk.

Biomarker profiling for lupus nephritis

Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE), which is associated with significant morbidity and mortality of SLE patients. The pathogenesis of LN involves multiple factors, including genetic predisposition, epigenetic regulation and environmental interaction. Over the last decade, omics-based techniques have been extensively utilized for biomarker screening and a wide variety of variations which are associated with SLE and LN have been identified at the levels of genomics, transcriptomics and proteomics. These studies and discoveries have expanded our understanding of the molecular basis of the disease and are important for identification of potential therapeutic targets for disease prediction and early treatment. In this review, we summarize some of the recent studies targeted at the identification of LN-associated biomarkers using genomics and proteomic approaches.

Development of a model of early-onset IgA nephropathy

ddY mice spontaneously develop IgA nephropathy (IgAN) with a variable age of disease onset. Establishing a model with early-onset IgAN could aid the investigation of mechanisms that underlie the pathogenesis of this disease. On the basis of histologic grading in serial biopsies, we previously classified ddY mice into early-onset, late-onset, and quiescent groups. Here, we selectively mated mice with the early-onset phenotype for >20 generations and established "grouped ddY" mice that develop IgAN within 8 weeks of age. Similar to human IgAN, the prognosis was worse for male mice than females. These mice homogeneously retained genotypes of four marker loci previously associated with the early-onset phenotype, confirming a close association of these loci with early-onset IgAN in ddY mice. Grouped ddY mice comprised two sublines, however, which had distinct genotypes at a susceptibility locus for high serum IgA levels, which maps within the Ig heavy-chain gene complex. The subline bearing the Igh-2(a) IgA allotype had a more rapid course of fatal disease and lower oligosaccharide content, suggesting that aberrant IgA glycosylation may promote the progression of murine IgAN. Taken together, these data indicate that grouped ddY mice may be a useful model for the identification of susceptibility genes and the underlying molecular mechanisms involved in the pathogenesis of human IgAN.

Uteroglobin: a steroid-inducible immunomodulatory protein that founded the Secretoglobin superfamily

Blastokinin or uteroglobin (UG) is a steroid-inducible, evolutionarily conserved, secreted protein that has been extensively studied from the standpoint of its structure and molecular biology. However, the physiological function(s) of UG still remains elusive. Isolated from the uterus of rabbits during early pregnancy, UG is the founding member of a growing superfamily of proteins called Secretoglobin (Scgb). Numerous studies demonstrated that UG is a multifunctional protein with antiinflammatory/ immunomodulatory properties. It inhibits soluble phospholipase A(2) activity and binds and perhaps sequesters hydrophobic ligands such as progesterone, retinols, polychlorinated biphenyls, phospholipids, and prostaglandins. In addition to its antiinflammatory activities, UG manifests antichemotactic, antiallergic, antitumorigenic, and embryonic growth-stimulatory activities. The tissue-specific expression of the UG gene is regulated by several steroid hormones, although a nonsteroid hormone, prolactin, further augments its expression in the uterus. The mucosal epithelia of virtually all organs that communicate with the external environment express UG, and it is present in the blood, urine, and other body fluids. Although the physiological functions of this protein are still under investigation, a single nucleotide polymorphism in the UG gene appears to be associated with several inflammatory/autoimmune diseases. Investigations with UG-knockout mice revealed that the absence of this protein leads to phenotypes that suggest its critical homeostatic role(s) against oxidative damage, inflammation, autoimmunity, and cancer. Recent studies on UG-binding proteins (receptors) provide further insight into the multifunctional nature of this protein. Based on its antiinflammatory and antiallergic properties, UG is a potential drug target.

Genetics of Human Lupus Nephritis

Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease in which glomerulonephritis represents one of the most severe clinical presentations. Numerous linkage and association studies, as well as the analysis of murine models, have provided ample evidence for a genetic basis for SLE. Genetic susceptibility to SLE results from the combined actions of multiple alleles, each of them conferring a modest incremental risk. SLE susceptibility genes have been identified in 3 major pathways: apoptosis, lymphocyte activation, and clearance of immune complexes and/or apoptotic debris. There also now is evidence that, within SLE patients, renal end-organ targeting also has a genetic basis, which can be divided into 2 branches. There is evidence that susceptibility alleles that are associated with a greater disease severity also are associated with lupus nephritis. There also is evidence for a set of kidney-specific genes that are likely to amplify or to sensitize to the autoimmune pathology.

Complex gene-gene interactions in multiple sclerosis: a multifactorial approach reveals associations with inflammatory genes

The complex inheritance involved in multiple sclerosis (MS) risk has been extensively investigated, but our understanding of MS genetics remains rudimentary. In this study, we explore 51 single nucleotide polymorphisms (SNPs) in 36 candidate genes from the inflammatory pathway and test for gene-gene interactions using complementary case-control, discordant sibling pair, and trio family study designs. We used a sample of 421 carefully diagnosed MS cases and 96 unrelated, healthy controls; discordant sibling pairs from 146 multiplex families; and 275 trio families. We used multifactor dimensionality reduction to explore gene-gene interactions. Based on our analyses, we have identified several statistically significant models including both main effect models and two-locus, three-locus, and four-locus epistasis models that predict MS disease risk with between approximately 61% and 85% accuracy. These results suggest that significant epistasis, or gene-gene interactions, may exist even in the absence of statistically significant individual main effects.

Association of uteroglobin G38A polymorphism with IgA nephropathy: a meta-analysis

Both uteroglobin knockout and antisense transgenic mice develop pathological and clinical features similar to immunoglobulin A (IgA) nephropathy. However, several association studies of uteroglobin G38A polymorphism and IgA nephropathy showed controversial findings. We used meta-analysis to assess the impact of the uteroglobin G38A polymorphism on susceptibility to and progression of IgA nephropathy. Six studies involving uteroglobin G38A genotyping of 930 patients with IgA nephropathy and 768 healthy controls were included. No significant publication bias was found (Egger's linear regression, P = 0.763; 95% confidence interval [CI], -0.610 to 0.476). All control samples were in Hardy-Weinberg proportion. No association between the AA genotype and risk for IgA nephropathy relative to both other genotypes (odds ratio [OR], 1.05; 95% CI, 0.71 to 1.54) or A allele and risk for IgA nephropathy (OR, 0.96; 95% CI, 0.84 to 1.11) were shown in the total meta-analysis. In both Asian and European subgroups, the overall effect of the AA genotype and A allele also showed no significant difference. There also was no significant association between uteroglobin AA genotype or A allele and IgA nephropathy progression (OR, 3.62; 95% CI, 0.59 to 22.34; OR, 2.19, 95% CI, 0.37 to 13.14, respectively). We suggest that uteroglobin G38A polymorphism is not related to the development and progression of IgA nephropathy.

Analysis of a uteroglobin gene polymorphism in childhood Henoch-Schonlein purpura

Uteroglobin (UG) is a pleiotropic protein with anti-inflammatory properties. Mice rendered genetically incapable of expressing UG develop a form of renal disease that closely resembles human IgA nephropathy (IgAN). Furthermore, a single nucleotide polymorphism in the UG gene (A38G) has been associated with rapid progression of human IgAN. We examined whether the A38G polymorphism is associated with childhood Henoch-Schonlein purpura (HSP), a form of vasculitis associated with IgAN-like renal disease. We examined the prevalence of the A38G polymorphism in 34 children with HSP and in 38 ethnically matched controls. Only one patient had clinically evident renal involvement. As compared with controls, the prevalence of the 38G allele was slightly increased in children with HSP, but this increase was not statistically significant. Our results do not support a role for UG in susceptibility to childhood HSP in the population studied. Larger studies involving more patients with renal disease will be necessary to define whether UG is associated with increased risk for HSP nephritis.

Genome-wide scan in a novel IgA nephropathy model identifies a susceptibility locus on murine chromosome 10, in a region syntenic to human IGAN1 on chromosome 6q22-23

Genetic factors are considered to be involved in the initiation and progression of IgA nephropathy (IgAN) on the basis of racial differences in the prevalence and familial aggregation. The ddY mouse is a spontaneous animal model of human IgAN, with a highly variable incidence and extent of glomerular injury as a result of the heterogeneous background, resembling the human situation. It was hypothesized that susceptibility genes for IgAN can be detected by a genome-wide scan using this model. First, serial renal biopsies were performed at 20, 40, and 60 wk of age in 361 ddY mice. The ddY mice were classified into three groups on the basis of the onset of glomerular injury: Early onset at 20 wk (31.9%), late onset at 40 wk (37.9%), and quiescent even at 60 wk (30.2%). The severity of glomerular lesions in both onset groups correlated with the intensity of glomerular IgA deposition but not with serum IgA level. The genome-wide scan with 270 microsatellite markers identified three chromosomal regions on chromosomes 1, 9, and 10, which were significantly associated with the glomerular injuries. Surprisingly, the peak marker D10MIT86 on chromosome 10 is located on the region syntenic to human 6q22-23 with IGAN1, which is the responsible candidate of familial IgAN. In addition, D1MIT16 on chromosome 1 was very closely located at the locus of selectin gene, which is a known candidate of human IgAN. In conclusion, the three-group ddY mouse model can be a useful tool for identifying the susceptibility genes and also to examine their roles in the pathogenesis of IgAN.

The mouse salivary androgen-binding protein (ABP) gene cluster on chromosomes 7: characterization and evolutionary relationships

Mouse salivary androgen-binding protein (ABP) is a pair of dimers, composed of an alpha subunit disulfide bridged to either a beta or a gamma subunit. It has been proposed that each subunit is encoded by a distinct gene: Abpa, Abpb, and Abpg for the alpha, beta, and gamma subunits, respectively. We report here the structures and sequences of the genes that encode these three subunits. Each gene has three exons separated by two introns. Mouse salivary ABP is a member of the secretoglobin family, and we compare the structure of the three ABP subunit genes to those of 18 other mammalian secretoglobins. We map the three genes as a gene cluster located 10 cM from the centromere of Chromosome (Chr) 7 and show that Abpa is the closest of the three to the gene for glucose phosphate isomerase (GPI) and that Abpg is the closest to the centromere, with Abpb mapping between them. Abpa is oriented in the opposite direction to Abpb and Abpg, with its 5' end directed toward their 5' ends. We compare the location of these genes with other secretoglobin genes in the mouse genome and with the known locations of secretoglobin genes in the human genome and present evidence that strong positive selection has driven the divergence of the coding regions of Abpb and Abpg since the putative duplication event that created them.