Genetic polymorphisms and susceptibility to parenchymal renal infection among pediatric patients

Genetic determinants of renal scarring in children with febrile UTI

BACKGROUND

Febrile urinary tract infections (UTIs) are among the most severe bacterial infections in infants, in which a subset of patients develops complications. Identifying infants at risk of recurrent infections or kidney damage based on clinical signs is challenging. Previous observations suggest that genetic factors influence UTI outcomes and could serve as predictors of disease severity. In this study, we conducted a nationwide survey of infant genotypes to develop a strategy for infection management based on individual genetic risk. Our aims were to identify genetic susceptibility variants for renal scarring (RS) and genetic host factors predisposing to dilating vesicoureteral reflux (VUR) and recurrent UTIs.

METHODS

To assess genetic susceptibility, we collected and analyzed DNA from blood using exome genotyping. Disease-associated genetic variants were identified through bioinformatics analysis, including allelic frequency tests and odds ratio calculations. Kidney involvement was defined using dimercaptosuccinic acid (DMSA) scintigraphy.

RESULTS

In this investigation, a cohort comprising 1087 infants presenting with their first episode of febrile UTI was included. Among this cohort, a subset of 137 infants who underwent DMSA scanning was subjected to gene association analysis. Remarkable genetic distinctions were observed between patients with RS and those exhibiting resolved kidney involvement. Notably, the genetic signature indicative of renal scarring prominently featured mitochondrial genes.

CONCLUSIONS

In this nationwide study of genetic susceptibility to RS after febrile UTIs in infancy, we identified a profile dominated by mitochondrial polymorphisms. This profile can serve as a predictor of future complications, including RS and recurrent UTIs.

Investigating the impact of the genetic variant CXCR1 (rs2234671) in individuals with urinary tract infections

BACKGROUND

Urinary tract infections (UTIs) are currently posing a worldwide health concern by affecting millions of people. The genetic variant rs2234671 in the CXCR1-interleukin-8 receptor is closely related to a raised UTI risk.

OBJECTIVES

In this work, the impact of CXCR1 (rs2234671) on UTI individuals was examined.

METHODS

The demographic features of 30 recurrent UTI patients and 20 controls were thoroughly investigated. Bacterial isolation and identification were performed by the implementation of cultural and biochemical methods. DNA extraction, purification of all samples from both patients and healthy people, and IL-8 rs2234671 (C/G) SNP genotyping using T-ARMS-PCR were performed. The significance of the results was evaluated by carrying out a statistical analysis.

FINDINGS

The patient's average age was 34.63 ± 11.44 years, and controls averaged 30.30 ± 8.59 years (P= 0.156). No significant gender difference existed (P= 0.804). Escherichia coli (63.3%) was predominant, followed by Proteus mirabilis (26.7%), Enterococcus faecalis (23.3%), Klebsiella pneumoniae (10.0%), and Pseudomonas aeruginosa (20.0%). No significant association was found between bacterial species frequency, age, or sex. From the CXCR1 (rs2234671) frequency comparison, a higher GG genotype incidence in UTI patients than controls was extracted (26.7% vs. 15.0%), though not statistically significant. Risk analysis revealed that GG homozygous and C/G heterozygous genotypes were not UTI risk factors (OR = 2.47 and OR = 1.85, respectively). Moreover, the allele frequencies displayed no significant difference between the patients and controls (G allele: 66.7% vs. 66.7%; C allele: 33.3% vs. 33.3%).

MAIN CONCLUSIONS

Although no significant association between CXCR1 (rs2234671) and UTI was found, the GG genotype may point to the increasing probability of UTI risk. Additional research is required to confirm and expand these conclusions.

Immunomodulation therapy offers new molecular strategies to treat UTI

Innovative solutions are needed for the treatment of bacterial infections, and a range of antibacterial molecules have been explored as alternatives to antibiotics. A different approach is to investigate the immune system of the host for new ways of making the antibacterial defence more efficient. However, the immune system has a dual role as protector and cause of disease: in addition to being protective, increasing evidence shows that innate immune responses can become excessive and cause acute symptoms and tissue pathology during infection. This role of innate immunity in disease suggests that the immune system should be targeted therapeutically, to inhibit over-reactivity. The ultimate goal is to develop therapies that selectively attenuate destructive immune response cascades, while augmenting the protective antimicrobial defence but such treatment options have remained underexplored, owing to the molecular proximity of the protective and destructive effects of the immune response. The concept of innate immunomodulation therapy has been developed successfully in urinary tract infections, based on detailed studies of innate immune activation and disease pathogenesis. Effective, disease-specific, immunomodulatory strategies have been developed by targeting specific immune response regulators including key transcription factors. In acute pyelonephritis, targeting interferon regulatory factor 7 using small interfering RNA or treatment with antimicrobial peptide cathelicidin was protective and, in acute cystitis, targeting overactive effector molecules such as IL-1β, MMP7, COX2, cAMP and the pain-sensing receptor NK1R has been successful in vivo. Furthermore, other UTI treatment strategies, such as inhibiting bacterial adhesion and vaccination, have also shown promise.

Hyperactivation of innate immunity is a disease determinant in urinary tract infections (UTIs). Modulation of innate immunity has promise as a therapy for UTIs. In this Review, the authors discuss potential mechanisms and immunomodulatory therapeutic strategies in UTIs.

Excessive innate immune responses to infection cause symptoms and pathology in acute pyelonephritis and acute cystitis.

Innate immunomodulation therapy is, therefore, a realistic option for treating these conditions.

Targeting excessive innate immune responses at the level of transcription has been successful in animal models.

Innate immunomodulation therapy reduces excessive inflammation and tissue pathology and accelerates bacterial clearance from infected kidneys and bladders in mice.

Innate immunomodulation therapy also accelerates the clearance of antibiotic-resistant bacterial strains.

Molecular determinants of disease severity in urinary tract infection

The most common and lethal bacterial pathogens have co-evolved with the host. Pathogens are the aggressors, and the host immune system is responsible for the defence. However, immune responses can also become destructive, and excessive innate immune activation is a major cause of infection-associated morbidity, exemplified by symptomatic urinary tract infections (UTIs), which are caused, in part, by excessive innate immune activation. Severe kidney infections (acute pyelonephritis) are a major cause of morbidity and mortality, and painful infections of the urinary bladder (acute cystitis) can become debilitating in susceptible patients. Disease severity is controlled at specific innate immune checkpoints, and a detailed understanding of their functions is crucial for strategies to counter microbial aggression with novel treatment and prevention measures. One approach is the use of bacterial molecules that reprogramme the innate immune system, accelerating or inhibiting disease processes. A very different outcome is asymptomatic bacteriuria, defined by low host immune responsiveness to bacteria with attenuated virulence. This observation provides the rationale for immunomodulation as a new therapeutic tool to deliberately modify host susceptibility, control the host response and avoid severe disease. The power of innate immunity as an arbitrator of health and disease is also highly relevant for emerging pathogens, including the current COVID-19 pandemic.

Urinary tract infection in pediatrics: an overview

OBJECTIVE

This review aimed to provide a critical overview on the pathogenesis, clinical findings, diagnosis, imaging investigation, treatment, chemoprophylaxis, and complications of urinary tract infection in pediatric patients.

SOURCE OF DATA

Data were obtained independently by two authors, who carried out a comprehensive and non-systematic search in public databases.

SUMMARY OF FINDINGS

Urinary tract infection is the most common bacterial infection in children. Urinary tract infection in pediatric patients can be the early clinical manifestation of congenital anomalies of the kidney and urinary tract (CAKUT) or be related to bladder dysfunctions. E. coli is responsible for 80-90% of community-acquired acute pyelonephritis episodes, especially in children. Bacterial virulence factors and the innate host immune systems may contribute to the occurrence and severity of urinary tract infection. The clinical presentation of urinary tract infections in children is highly heterogeneous, with symptoms that can be quite obscure. Urine culture is still the gold standard for diagnosing urinary tract infection and methods of urine collection in individual centers should be determined based on the accuracy of voided specimens. The debate on the ideal imaging protocol is still ongoing and there is tendency of less use of prophylaxis. Alternative measures and management of risk factors for recurrent urinary tract infection should be emphasized. However, in selected patients, prophylaxis can protect from recurrent urinary tract infection and long-term consequences. According to population-based studies, hypertension and chronic kidney disease are rarely associated with urinary tract infection.

CONCLUSION

Many aspects regarding urinary tract infection in children are still matters of debate, especially imaging investigation and indication of antibiotic prophylaxis. Further longitudinal studies are needed to establish tailored approach of urinary tract infection in childhood.

Influenza A (H1N1) virus infection and TNF-308, IL6, and IL8 polymorphisms in Egyptian population: a case-control study

BACKGROUND

The importance of influenza is increasing mainly because of the appearance of novel pandemic strains such as swine and avian. Each year, influenza has spread around the world causing about 250,000-500,000 deaths and more than 5 million cases of severe illness.The objective is as follows: evaluating the outcomes of patients with influenza A (H1N1) virus in relation to certain TNF-308, IL6, and IL8 polymorphisms and identifying the associated factors with the severe outcome.

SUBJECT AND METHODS

This is a case-control study. The cases were patients confirmed by real-time polymerase chain reaction (RT-PCR) to be influenza A (H1N1) virus infected. The controls were healthy individuals. Medical history and outcome of the disease was registered. In all study participants, polymorphisms of TNF rs1800629, IL6 rs18138879, and IL8 rs4073; odds ratio (OR); and the 95% confidence interval (95% CI) were calculated.

RESULTS

Infection with influenza A (H1N1) virus was associated more with the following genotypes: TNF-308 AA (OR = 4.041; 95% CI = 1.215-13.4) and IL8 AA (OR = 3.273; 95% CI = 1.372-7.805). According to our study results, HCV (OR = 3.2, 95% CI 1.2-8.5), renal disease (OR = 3.4, 95% CI 0.9-13.6), cancer (OR = 3.1, 95% CI 0.3-31.1), TB (OR = 8.4, 95% CI 1.8-39.7), ICU (OR = 2.9, 95%1.2-7.1), and mortality (OR = 7.9, 95% CI 0.9-67.4) are considered as risk factors for influenza A (H1N1)-infected patients.

CONCLUSIONS

Our findings concluded that TNF-308 (AA) and IL8 (AA) polymorphisms may increase the susceptibility to be infected with H1N1influenza virus.

A Putative Role of Apolipoprotein L1 Polymorphism in Renal Parenchymal Scarring Following Febrile Urinary Tract Infection in Nigerian Under-Five Children: Proposal for a Case-Control Association Study

Background

Although urinary tract infection (UTI) resolves with prompt treatment in a majority of children, some children, especially those aged less than 5 years, also develop renal parenchymal scarring (RPS). RPS causes high blood pressure that may lead to severe chronic kidney disease and end-stage renal disease (ESRD). Although the risk of UTI is higher in white children than in black children, it is unknown whether RPS is more common in white children than in black children as data are scarce in this regard. A common genetic predisposition to kidney disease in African Americans and the sub-Saharan African blacks is the possession of apolipoprotein L1 (APOL1). APOL1 risk variants regulate the production of APOL1. APOL1 circulates in the blood, and it is also found in the kidney tissue. While circulating, APOL1 kills the trypanosome parasites; an increased APOL1 in kidney tissues, under the right environmental conditions, can also result in the death of kidney tissue (vascular endothelium, the podocytes, proximal tubules, and arterial cells), which, ultimately, is replaced by fibrous tissue. APOL1 may influence the development of RPS, as evidence affirms that its expression is increased in kidney tissue following UTI caused by bacteria. Thus, UTI may be a putative environmental risk factor responsible for APOL1-induced kidney injury.

Objective

The aim of this proposal was to outline a study that seeks to determine if the possession of two copies of either G1 or G2 APOL1 variant increases the risk of having RPS, 6 months following a febrile UTI among Nigerian under-five children.

Methods

This case-control association study seeks to determine whether the risk of RPS from febrile UTI is conditional on having 2 APOL1 risk alleles (either G1 or G2). Cases will be children with a confirmed RPS following a febrile UTI. Controls will be age-, gender-, and ethnic-matched children with a febrile UTI but without RPS. Children with vesicoureteral reflux and other congenital anomalies of the urinary tract are to be excluded. Association between predictor variables (ethnicity, APOL1 G1 or G2, and others) and RPS will be tested at bivariate logistic regression analyses. Predictors that attained significance at a P value of ˂.05 will be considered for multiple logistic regressions. Likelihood-based tests will be used for hypothesis testing. Estimation will be done for the effect size for each of the APOL1 haplotypes using a generalized linear model.

Results

The study is expected to last for 3 years.

Conclusions

The study is contingent on having a platform for undergoing a research-based PhD program in any willing university in Europe or elsewhere. The findings of this study will be used to improve the care of African children who may develop RPS following febrile UTI.

Registered Report Identifier

RR1-10.2196/9514

Association between interleukin 8-receptor gene (CXCR1 and CXCR2) polymorphisms and urinary tract infection: Evidence from 4097 subjects

AIM

The aim of this study was to determine whether a correlation exists between interleukin-8 receptor polymorphisms and urinary tract infection (UTI) susceptibility.

METHODS

We systematically searched electronic databases including PubMed, Embase, China National Knowledge Infrastructure, and Web of Science up to 5 November 2017 to select appropriate studies that focused on C-X-C chemokine receptor type 1 and/or 2 (CXCR1, CXCR2) polymorphisms with susceptibility to UTI. Eight case-control studies including 2085 patients with UTI and 2012 controls were enrolled in this study. Seven studies of CXCR1 rs2234671 and two studies of rs3138086 were included in the meta-analyses. Pooled odds ratio (OR) and corresponding 95% confidence interval (CI) were synthesized using fixed-effects or random-effects model according to heterogeneity.

RESULTS

No significant correlations were found between CXCR1 rs2234671 and rs3138086 polymorphisms and UTI susceptibility. However, subgroup analysis showed that rs2234671 was associated with an increased risk of UTI under allelic comparisons (C vs. G, OR = 1.95, 95% CI = 1.07-3.55), heterozygous model (GC vs. GG, OR = 1.93, 95% CI = 1.06-3.50), and dominant model (GC + CC vs. GG, OR = 1.98, 95% CI = 1.07-3.69) in children, especially in paediatric patients with acute pyelonephritis (allelic, OR = 2.43, 95% CI = 1.28-4.60; heterozygous, OR = 2.40, 95% CI = 1.24-4.62; dominant, OR = 2.48, 95% CI = 1.26-4.88). Furthermore, these results remained the same after eliminating paediatric patients with vesicoureteral reflux.

CONCLUSION

CXCR1 rs2234671 polymorphism might be associated with an increased risk of UTI in children.

Cytokine Gene Polymorphisms Associated With Various Domains of Quality of Life in Women With Breast Cancer

CONTEXT

Little is known about the phenotypic and molecular characteristics associated with various domains of quality of life (QOL) in women after breast cancer surgery.

OBJECTIVES

In a sample of women with breast cancer (n = 398), purposes were as follows: to identify latent classes with distinct trajectories of QOL from before surgery through six months after surgery and to evaluate for differences in demographic and clinical characteristics, as well as for polymorphisms in cytokine genes, between these latent classes.

METHODS

Latent class analyses were done to identify subgroups of patients with distinct QOL outcomes. Candidate gene analyses were done to identify cytokine gene polymorphisms associated with various domains of QOL (i.e., physical, psychological, spiritual, social).

RESULTS

One latent class was identified for the psychological and spiritual domains. Two latent classes were identified for the social domain and overall QOL scores. Three latent classes were identified for the physical domain. For the physical and social domains, as well as for the overall QOL scores, distinct phenotypic characteristics (i.e., younger age, poorer functional status, higher body mass index, and receipt of adjuvant chemotherapy) and a number of cytokine gene polymorphisms (CXCL8, NFKB2, TNFSF, IL1B, IL13, and NFKB1) were associated with membership in the lower QOL classes.

CONCLUSIONS

Findings suggest that women experience distinctly different physical well-being, social well-being, and total QOL outcomes during and after breast cancer surgery. The genetic associations identified suggest that cytokine dysregulation influences QOL outcomes. However, specific QOL domains may be impacted by different cytokines.

Impact of cytokine genetic polymorphisms on the risk of renal parenchymal infection in children

BACKGROUND

Acute pyelonephritis is associated with renal scarring in up to 30% of patients. Renal scarring may cause significant long-term morbidity. The pathogenesis of acute pyelonephritis remains unclear, although it involves interaction among uroepithelium, the immune system cells, and the locally produced cytokines. That some UTI-prone children develop acute pyelonephritis, and eventually renal parenchymal scarring, suggests a genetic role. Interleukin-6, interleukin-8, chemokine receptor-1 (CXCR1), and tumor necrosis factor-alpha (TNFα), the key regulators of the host immune responses, are proteins whose secretion is controlled by genes. We postulated that functional polymorphic variants of their genes might have a role in APN susceptibility.

OBJECTIVES

We sought to investigate a possible association of the common functional polymorphisms in genes encoding IL-6, IL-8, CXCR1, and TNFα with the risk of APN in children.

METHODS

Urine culture was used to diagnose 300 children with UTI, of mean age of 51.31 ± 37.4 months (2-180 months). 99Tc-DMSA scans diagnosed 86 children with APN. Follow-up scans identified new renal scars in 18 children. Six functional single-nucleotide polymorphisms (SNPs) in genes encoding IL-6, IL-8, CXCR1, and TNFα were genotyped in all subjects (IL-6 rs1800795 (-174G/C), IL-6 rs1800796 (-572G/C), IL-8 rs2227306 (781C/T), IL8 rs4073 (-251A/T), CXCR1 rs2234671 (2607G/C), and TNFα rs1800629 (-308G/A)).

RESULTS

TT genotype of IL-8 -251A/T polymorphism was significantly higher in APN patients (26.7%) than those with lower UTI (11.7%, p = 0.01) and control individuals (12.2%, p = 0.002). T allele was significantly more common in APN than in lower UTI (p = 0.025) and was significantly more common in APN (46%) than in the controls (p = 0.001). Similarly, TT genotype of IL-8 781C/T polymorphism was significantly more common in APN patients (31.4%) than those with lower UTI (17.3%, p = 0.003) and the controls (14.3%, p = 0.001). T allele was significantly more common in APN (55%) than lower UTI (40%, p = 0.005) and controls (37%, p = 0.001). However, IL-8 -251A/T and +781C/T SNPs did not qualify as an independent risk for parenchymal infection (OR 1.9, 95% CI 0.68-2.6, p = 0.13 and OR 2.3, 95% CI 0.89-3.7, p = 0.091, respectively). Lower UTI did not differ from the controls. The frequency of the genotypes and alleles of IL-6, CXCR1, and TNFα SNPs did not differ significantly among the different groups of the study.

CONCLUSION

IL-8 -251A/T and +781C/T SNPs are associated with susceptibility to renal parenchymal infection in children and could be implicated in APN risk. However, none of these variants could clearly and independently predict this risk.

Testing an association between TLR4 and CXCR1 gene polymorphisms with susceptibility to urinary tract infection in type 2 diabetes in north Indian population

BACKGROUND

Genetic variations of Toll like receptor 4 (TLR4) and CXC-chemokine receptor type1 (CXCR1), the key elements of innate immune system and their association with urinary tract infection (UTI) were studied in general population. In present study we investigate genetic variation of these genes in diabetic patients (3 to 4 times higher prevalence of UTI in comparison to general population).

METHODS

A total 1100 subjects (318 diabetic patients with UTI, 324 diabetic patients without UTI, 200 non-diabetic UTI patients and 260 age matched healthy control) were enrolled in the study. SNPs of TLR4 rs4986790, rs4986791 and CXCR1 rs2234671 was assessed by PCR-RFLP and PCR-SSP respectively.

RESULTS

Statistical analysis revealed that A/G genotype and G allele of TLR4 rs4986790 are significantly associated with UTI in both diabetics and nondiabetic patients in comparison to healthy control. Similarly CT genotype and T allele of TLR4 rs4986791 are also significantly associated with UTI in both groups. We also found that prevalence of A/G genotype of TLR4 rs4986790 and CT genotype of TLR4 rs4986791 are significantly higher in patients of diabetes with UTI in comparison to diabetic patients without UTI. We did not find any association of CXCR1 rs2234671 polymorphism with UTI by comparing with any group.

CONCLUSION

We found that TLR4 rs4986790 and rs4986791 gene polymorphism is a risk for UTI development in both diabetic and nondiabetic patients in north Indian population.

The Genetics of Urinary Tract Infections and the Innate Defense of the Kidney and Urinary tract

The urinary tract is a sterile organ system. Urinary tract infections (UTIs) are common and often serious infections. Research has focused on uropathogen, environment, and host factors leading to UTI pathogenesis. A growing body of evidence exists implicating genetic factors that can contribute to UTI risks. In this review, we highlight genetic variations in aspects of the innate immune system critical to the host response to uropathogens. This overview includes genetic variations in pattern recognition receptor molecules, chemokines/cytokines, and neutrophil activation. We also comprehensively cover murine knockout models of UTI, genetic variations involved in renal scarring as a result of ascending UTIs, and asymptomatic bacteriuria.

Polymorphisms in Host Immunity-Modulating Genes and Risk of Invasive Aspergillosis: Results from the AspBIOmics Consortium

Recent studies suggest that immune-modulating single-nucleotide polymorphisms (SNPs) influence the risk of developing cancer-related infections. Here, we evaluated whether 36 SNPs within 14 immune-related genes are associated with the risk of invasive aspergillosis (IA) and whether genotyping of these variants might improve disease risk prediction. We conducted a case-control association study of 781 immunocompromised patients, 149 of whom were diagnosed with IA. Association analysis showed that the IL4Rrs2107356 and IL8rs2227307 SNPs (using dbSNP numbering) were associated with an increased risk of IA (IL4Rrs2107356 odds ratio [OR], 1.92; 95% confidence interval [CI], 1.20 to 3.09; IL8rs2227307 OR, 1.73; 95% CI, 1.06 to 2.81), whereas the IL12Brs3212227 and IFNγrs2069705 variants were significantly associated with a decreased risk of developing the infection (IL12Brs3212227 OR, 0.60; 95% CI, 0.38 to 0.96; IFNγrs2069705 OR, 0.63; 95% CI, 0.41 to 0.97). An allogeneic hematopoietic stem cell transplantation (allo-HSCT)-stratified analysis revealed that the effect observed for the IL4Rrs2107356 and IFNγrs2069705 SNPs was stronger in allo-HSCT (IL4Rrs2107356 OR, 5.63; 95% CI, 1.20 to 3.09; IFNγrs2069705 OR, 0.24; 95% CI, 0.10 to 0.59) than in non-HSCT patients, suggesting that the presence of these SNPs renders patients more vulnerable to infection, especially under severe and prolonged immunosuppressive conditions. Importantly, in vitro studies revealed that carriers of the IFNγrs2069705C allele showed a significantly increased macrophage-mediated neutralization of fungal conidia (P = 0.0003) and, under stimulation conditions, produced higher levels of gamma interferon (IFNγ) mRNA (P = 0.049) and IFNγ and tumor necrosis factor alpha (TNF-α) cytokines (P value for 96 h of treatment with lipopolysaccharide [PLPS-96 h], 0.057; P value for 96 h of treatment with phytohemagglutinin [PPHA-96 h], 0.036; PLPS+PHA-96 h = 0.030; PPHA-72 h = 0.045; PLPS+PHA-72 h = 0.018; PLPS-96 h = 0.058; PLPS+PHA-96 h = 0.0058). Finally, we also observed that the addition of SNPs significantly associated with IA to a model including clinical variables led to a substantial improvement in the discriminatory ability to predict disease (area under the concentration-time curve [AUC] of 0.659 versus AUC of 0.564; P-2 log likehood ratio test = 5.2 · 10(-4) and P50.000 permutation test = 9.34 · 10(-5)). These findings suggest that the IFNγrs2069705 SNP influences the risk of IA and that predictive models built with IFNγ, IL8, IL12p70, and VEGFA variants can used to predict disease risk and to implement risk-adapted prophylaxis or diagnostic strategies.

Genetic Polymorphisms in Inflammasome-Dependent Innate Immunity among Pediatric Patients with Severe Renal Parenchymal Infections

Background

Inflammasome innate immune response activation has been demonstrated in various inflammatory diseases and microbial infections. However, to our knowledge, no study has examined the inflammasome-dependent pathways in patients with urinary tract infection. Defective or variant genes associated with innate immunity are believed to alter the host’s susceptibility to microbial infection. This study investigated genetic polymorphisms in genes encoding inflammasomes and the subsequent released cytokines in pediatric patients with severe renal parenchymal infections.

Methodology

This study included patients diagnosed with acute pyelonephritis (APN) and acute lobar nephronia (ALN) who had no underlying disease or structural anomalies other than vesicoureteral reflux (VUR). Single nucleotide polymorphism (SNP) genotyping was performed in the genes associated with inflammasome formation and activation (NLRP3, CARD8) and subsequent IL–1β cytokine generation (IL–1β).

Principal Findings

A total of 40 SNPs were selected for initial genotyping. Analysis of samples from 48 patients each and 96 controls revealed that only nine SNPs (five SNPs in NLRP3; three SNPs in CARD8; one SNP in IL–1β) had heterozygosity rates >0.01. Hardy–Weinberg equilibrium was satisfied for the observed genotype frequencies of these SNPs. Analysis excluding patients with VUR, a well-known risk factor for severe UTIs, revealed a lower frequency of the CC genotype in NLRP3 (rs4612666) in patients with APN and ALN than in controls. Correction for multiple-SNP testing showed that the non-VUR subgroup of the APN+ALN combined patient groups remained significantly different from the control group (P < 0.0055).

Conclusions

This study is the first to suggest that the inflammasome-dependent innate immunity pathway is associated with the pathogenesis of pediatric severe renal parenchymal infections. Further investigation is warranted to clarify its pathogenic mechanism.

Toll-like receptor 4 gene polymorphism downregulates gene expression and involves in susceptibility to bladder cancer

Bladder cancer is the ninth most frequent malignancy in China. Toll-like receptor 4 (TLR4) is expressed on various cells and greatly involves in immune responses. Genetic polymorphism may affect the pathogenesis of diseases through various pathways. In the current study, we evaluated the association between genetic polymorphisms in TLR4 and risk of bladder cancer. We also examined the effect of the polymorphisms on gene expression. The TLR4 -729G/C and -260G/C polymorphisms were genotyped in 282 bladder cancer patients and 298 healthy controls in the Chinese population. Results showed that subjects with -729GC genotype are at significantly higher risk of bladder cancer than those with GG genotype [odds ratio (OR) = 2.50, 95% confidence interval (CI) = 1.39-4.48, P = 0.002]. Similarly, TLR4 -729C allele revealed a positive association with the disease (OR = 2.39, P = 0.002). The other polymorphism, TLR4 -260G/C, did not present clear correlations with bladder cancer. To understand the function of the polymorphisms, we evaluated TLR4 messenger RNA (mRNA) and protein levels in CD4+ T cells, CD8+ T cells, and monocytes from subjects carrying different TLR4 genotypes. Results revealed that subjects carrying -729GC genotype had significantly downregulated mRNA and protein levels of TLR4 in CD4+ T cells, CD8+ T cells, and monocytes compared to those carrying GG genotype. However, subjects with -260G/C polymorphism did not show any differences in gene expression from immune cells These data suggest that TLR4 polymorphism is associated with increased susceptibility to bladder cancer possibly by downregulating gene expression in various immune cells.

The innate immune response during urinary tract infection and pyelonephritis

Despite its proximity to the fecal flora, the urinary tract is considered sterile. The precise mechanisms by which the urinary tract maintains sterility are not well understood. Host immune responses are critically important in the antimicrobial defense of the urinary tract. During recent years, considerable advances have been made in our understanding of the mechanisms underlying immune homeostasis of the kidney and urinary tract. Dysfunctions in these immune mechanisms may result in acute disease, tissue destruction and overwhelming infection. The objective of this review is to provide an overview of the innate immune response in the urinary tract in response to microbial assault. In doing so, we focus on the role of antimicrobial peptides-a ubiquitous component of the innate immune response.

Pattern recognition receptors and the inflammasome in kidney disease

Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain receptors (NLRs) are families of pattern recognition receptors that, together with inflammasomes, sense and respond to highly conserved pathogen motifs and endogenous molecules released upon cell damage or stress. Evidence suggests that TLRs, NLRs and the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome have important roles in kidney diseases through regulation of inflammatory and tissue-repair responses to infection and injury. In this Review, we discuss the pathological mechanisms that are related to TLRs, NLRs and NLRP3 in various kidney diseases. In general, these receptors are protective in the host defence against urinary tract infection, but can sustain and self-perpetuate tissue damage in sterile inflammatory and immune-mediated kidney diseases. TLRs, NLRs and NLRP3, therefore, have become promising drug targets to enable specific modulation of kidney inflammation and suppression of immunopathology in kidney disease.

Association of interleukin-10 gene promoter polymorphisms with susceptibility to acute pyelonephritis in children

Interleukin-10 (IL-10) is a potent inhibitor of leukocyte chemotaxis, bacterial killing in phagocytes and synthesis of pro-inflammatory cytokines and chemokines, and recent studies have suggested an important role for this immunoregulatory cytokine in the pathogenesis of urinary tract infections (UTIs). Therefore, the gene encoding IL-10 (IL10) is an attractive candidate for association studies attempting to identify susceptibility genes conferring risk of UTIs. In this case-control study, we aimed to investigate the association of single nucleotide polymorphisms (SNPs) in the promoter region of IL10 with acute pyelonephritis in the Slovak population. Polymerase chain reaction with sequence-specific primers was used to analyse IL10 -1082A/G (rs1800896), -819C/T (rs1800871) and -592C/A (rs1800872) SNPs in 147 children with acute pyelonephritis and 215 healthy controls. Comparison of patients with healthy controls using the logistic regression analysis revealed significantly increased risk of developing recurrent attacks of acute pyelonephritis for -1082 G allele in a dominant genetic model GG (GG + AG vs. AA, P = 0.019, odds ratio (OR) = 2.26). A similar tendency was also found when the recurrent acute pyelonephritis subgroup was compared to episodic pyelonephritis cases (GG + AG vs. AA, P = 0.009, OR = 3.38). In conclusion, our results suggest that IL10 -1082 A/G SNP is a susceptibility factor for development of recurrent attacks of acute pyelonephritis.

Plasma cytokine levels and cytokine gene polymorphisms in Mexican patients during the influenza pandemic A(H1N1)pdm09

BACKGROUND

In Mexico, the initial severe cases of the 2009 influenza pandemic virus A (H1N1) [A(H1N1)pdm09] were detected in early March. The immune mechanisms associated with the severe pneumonia caused by infection with this new virus have not been completely elucidated. Polymorphisms in interleukin genes have previously been associated with susceptibility to infectious diseases due to their influence on cytokine production.

OBJECTIVES

The present case-control study was performed to compare several immunologic and genetic parameters of patients and controls during the initial phase of the pandemic.

STUDY DESIGN

Sixty-five patients who were hospitalized due to infection with the influenza A(H1N1)pdm09 virus and 46 healthy controls were studied. A hemagglutination inhibition assay (HIA) was performed to measure anti-influenza antibody titers in these subjects. Protein levels of the cytokines interleukin (IL)-4, IL-6, IL-8, IL-10, tumor necrosis factor-α (TNFα), interferon gamma (IFNγ), transforming growth factor beta (TGFβ)1 and TGFβ2 were quantified in plasma. Single nucleotide polymorphisms in IL6, IL10 and TNFα were also assessed.

RESULTS

Influenza patients had lower antibody titers and produced significantly higher levels of IL-6, IL-10 and TNFα than healthy controls. The frequencies of the TNFα -308G, IL-10 -592C and IL-10 -1082A alleles and the IL10 -1082(A/A) genotype were associated with susceptibility to severe disease, while the haplotypes TNFα AG and IL-10 GTA and GCA were associated with protection from severe disease [P=0.016, OR (CI)=0.11 (0.01-0.96); P=0.0187, OR (CI)=0.34 (0.13-0.85); P=0.013, OR (CI)=0.39 (0.18-0.83)].

CONCLUSIONS

This study demonstrates that the influenza A(H1N1)pdm09 patients and healthy controls have different profiles of immune parameters and that there is an association between IL-10 and TNFα polymorphisms and the outcome of this disease.

Genetic polymorphisms in Toll-like receptors among pediatric patients with renal parenchymal infections of different clinical severities

Background

Although several studies have suggested single gene defects or variations in the genes associated with host immune response could confer differences in susceptibility to urinary pathogen invasion, no studies have examined the genetic polymorphisms in various toll-like receptors (TLRs) that activate innate immune responses in pediatric renal parenchymal infections of different clinical severities, namely acute pyelonephritis and the clinically more severe disease, acute lobar nephronia.

Methodology

Patients who fulfilled the diagnostic criteria for acute pyelonephritis (APN) and acute lobar nephronia (ALN) without underlying diseases or structural anomalies, except for vesicoureteral reflux (VUR), were enrolled. Genotyping of the single nucleotide polymorphisms (SNPs) in the genes encoding TLR-1, TLR-2, TLR-4, TLR-5, and TLR-6 was performed by matrix-assisted laser desorption/ionization time-of-flight-based mini-sequencing analysis.

Principal Findings

A total of 16 SNPs were selected for genotyping. Analysis of 96 normal and 48 patients’ samples revealed that only four SNPs had heterozygosity rates >0.01. These SNPs were selected for further investigation. Hardy-Weinberg equilibrium was satisfied for the observed genotype frequencies. Statistically significant differences in the genotype frequency of TLR-2 (rs3804100, T1350C) between controls and ALN or (APN+ALN) combined group were identified using the recessive model with the correction for multiple-SNP testing. Further genotype pattern frequency analysis in TLR-2 SNPs (rs3804099 and rs3804100) showed significantly reduced occurrence of the rare allele homozygote (CC+CC) in the no-VUR subgroup of APN and ALN cases.

Conclusions

As the inflammatory responses in ALN patients are more severe than those in APN patients (higher CRP levels, longer duration of fever after antibiotic treatment), these findings suggest that the genetic variant in TLR-2 (rs3804100, T1350C) may protect the host from severe urinary tract infections as ALN.

Update on recent guidelines for the management of urinary tract infections in children: the shifting paradigm

PURPOSE OF REVIEW

Recent guidelines on the management of urinary tract infections (UTIs) in children have seen a shift from aggressive imaging studies and the use of prophylactic antibiotics to a more restrictive and targeted approach. This review focuses on new additions to the literature on management of UTI from January 2011 to September 2012.

RECENT FINDINGS

The causal relationship between UTI-vesicoureteral reflux (VUR) and renal scarring has been challenged by several studies. Concerns about unnecessary exposure to ionizing radiation, invasiveness of some of the procedures, and risk of infection have also been raised. With improved prenatal ultrasound, a 'top-down' approach to investigating febrile UTI in children using renal bladder ultrasound alone as an initial study has become popular. Several studies have reported that prophylactic antibiotics and imaging studies after first UTI can be reduced substantially without affecting the risk of recurrent UTI or renal scarring.

SUMMARY

The use of targeted imaging approach in evaluating febrile UTI in children may lead to improved resource use and reduction of potential harmful procedures and interventions, without affecting outcomes of UTI in children. Providers using current guidelines should endeavor to collect practice-based evidence to validate and inform future guidelines.

Pandemic influenza A/H1N1 virus infection and TNF, LTA, IL1B, IL6, IL8, and CCL polymorphisms in Mexican population: a case-control study

Background

Some patients have a greater response to viral infection than do others having a similar level of viral replication. Hypercytokinemia is the principal immunopathological mechanism that contributes to a severer clinical course in cases of influenza A/H1N1. The benefit produced, or damage caused, by these cytokines in severe disease is not known. The genes that code for these molecules are polymorphic and certain alleles have been associated with susceptibility to various diseases. The objective of the present study was to determine whether there was an association between polymorphisms of TNF, LTA, IL1B, IL6, IL8, and CCL1 and the infection and severity of the illness caused by the pandemic A/H1N1 in Mexico in 2009.

Methods

Case–control study. The cases were patients confirmed with real time PCR with infection by the A/H1N1 pandemic virus. The controls were patients with infection like to influenza and non-familial healthy contacts of the patients with influenza. Medical history and outcome of the disease was registered. The DNA samples were genotyped for polymorphisms TNF rs361525, rs1800629, and rs1800750; LTA rs909253; IL1B rs16944; IL6 rs1818879; IL8 rs4073; and CCL1 rs2282691. Odds ratio (OR) and the 95% confidence interval (95% CI) were calculated. The logistic regression model was adjusted by age and severity of the illness in cases.

Results

Infection with the pandemic A/H1N1 virus was associated with the following genotypes: TNF rs361525 AA, OR = 27.00; 95% CI = 3.07–1248.77); LTA rs909253 AG (OR = 4.33, 95% CI = 1.82–10.32); TNF rs1800750 AA (OR = 4.33, 95% CI = 1.48–12.64); additionally, LTA rs909253 AG showed a limited statistically significant association with mortality (p = 0.06, OR = 3.13). Carriers of the TNF rs1800629 GA genotype were associated with high levels of blood urea nitrogen (p = 0.05); those of the TNF rs1800750 AA genotype, with high levels of creatine phosphokinase (p=0.05). The IL1B rs16944 AA genotype was associated with an elevated number of leukocytes (p <0.001) and the IL8 rs4073 AA genotype, with a higher value for P_aO₂ mm Hg.

Conclusion

The polymorphisms of genes involved in the inflammatory process contributed to the severity of the clinical behavior of infection by the pandemic influenza A/H1N1 virus.

Genetic variations of interleukin-8, CXCR1 and CXCR2 genes and risk of acute pyelonephritis in children

Acute pyelonephritis (APN) is the most severe form of urinary tract infection, the etiopathogenesis of which is still not well understood. Previous studies demonstrated that chemotaxis of neutrophils into the tissue and across the infected epithelial layer is a key step in rapid bacterial clearance. Variations within genes encoding the major chemokine interleukin-8 and its receptors CXCR1 and CXCR2 are therefore attractive candidates for participation in genetic predisposition to APN. The aim of our study was to evaluate the association of single nucleotide polymorphisms (SNPs) -251 T/A, +781 C/T, +1633 C/T and +2767 A/T in the IL-8 gene, +2608 G/C in the CXCR1 gene and +1208 C/T in the CXCR2 gene with susceptibility to APN in the Slovak population. PCR-SSP and PCR-RFLP were used to genotype SNPs in 147 children with APN (62 with recurrent and 85 with episodic form) and 215 healthy individuals. Statistical analysis revealed significantly increased frequency of CXCR1 +2608 C allele (P = 0.0238, OR = 2.452, 95% CI = 1.147-5.243) and GC genotype (P = 0.0201, OR = 2.627, 95% CI = 1.188-5.810) and lower frequency of CXCR2 +1208 T allele (P = 0.0408, OR = 0.645, 95% CI = 0.429-0.972) and TT+TC genotypes (P = 0.0497, OR = 0.5273, 95% CI = 0.288-0.964) in patients with recurrent APN compared with healthy controls. Furthermore, the A allele of IL-8 -251 T/A SNP was also significantly overrepresented in patients with recurrent APN when compared with those with only single episode of APN (P = 0.0439, OR = 1.627, 95% CI = 1.019-2.599). Our results indicate that the minor CXCR1 +2608 C allele is associated with significantly increased susceptibility to APN in childhood, while the CXCR2 +1208 T allele confers protection from recurrent APN. Moreover, allele A of the IL-8 -251 T/A may also increase the risk of developing recurrent attacks after the first-time APN.