Iron-related proteins: candidate urine biomarkers in childhood HIV-associated renal diseases

Microalbuminuria and Urinary Neutrophil Gelatinase-associated Lipocalin (uNGAL) in human immunodeficiency virus infected children

Introduction:

Renal dysfunction and progression to end stage renal disease is well known in human immunodeficiency virus (HIV) infection. We studied the role of microalbuminuria and urinary NGAL levels in children with HIV infection for the prediction of renal dysfunction.

Design and Methods:

A cross-sectional study was carried out and 60 HIV infected children, aged (18 months to 15 years) were screened for microalbuminuria by nephelometry and for uNGAL by ELISA. Thirty healthy children were screened for uNGAL for normative data in Indian children.

Results:

The prevalence of microalbuminuria in studied population was 3.3%. The mean uNGAL and uNGAL/creatinine in study population was higher than controls (26.94 ± 93.12 ng/ml vs. 88.94 ± 345.20 mcg/g, and 15.53 ± 37.52 ng/ml vs. 30.12 ± 78.66 ng/ml; P = 0.003, P = 0.002). Children with lower CD4 counts had significant higher mean Albumin Creatinine Ratio (ACR) and mean uNGAL; P = 0.03, P = 0.01.

Conclusions:

uNGAL and urine microalbumin are useful biomarkers of early tubular and glomerular injury in children with HIV infection.

Profiling Biomarkers in HIV Glomerular Disease – Potential for the Non-Invasive Diagnosis of HIVAN?

Background

There is a wide spectrum of kidney pathology in human immunodeficiency virus (HIV) infection, affecting all structures of the kidney. The histology of HIV chronic kidney disease (CKD) is diverse, ranging from HIV-associated nephropathy (HIVAN) to focal glomerulosclerosis (FSGS), HIV-immune complex disease (HIV-ICD), other glomerulopathies and tubulo-interstitial nephritis. Definitive diagnosis is by kidney biopsy, an invasive procedure. However, serum and urinary biomarkers may be useful in predicting the histological diagnosis of HIVAN.

Purpose

We wished to determine the utility of serum and urinary biomarkers in predicting the histological diagnosis of HIVAN.

Patients and Methods

We measured neutrophil gelatinase-associated lipocalin (NGAL), cystatin C, transforming growth factor (TGF)-β isoforms and bone morphogenetic protein (BMP)-7 in the serum and urine in patients with different histological forms of HIV glomerular disease.

Results

In HIVAN, we demonstrated increased levels of serum cystatin C and increased levels of serum and urinary NGAL. Urinary TGF-β1 and TGF-β2 levels were elevated in HIV-positive patients with CKD but were not significantly different in the different HIV histologies, while urinary BMP-7 levels were elevated in minimal change disease.

Conclusion

This study confirmed the presence of increased serum and urinary biomarkers of tubular injury in patients with HIVAN, and increased urinary biomarkers of fibrosis in HIV CKD, and may indicate their value as a non-invasive diagnostic tool for the diagnosis of HIVAN.

Lights and Shadows of TORCH Infection Proteomics

Congenital abnormalities cause serious fetal consequences. The term TORCH is used to designate the most common perinatal infections, where: (T) refers to toxoplasmosis, (O) means "others" and includes syphilis, varicella-zoster, parvovirus B19, zika virus (ZIKV), and malaria among others, (R) refers to rubella, (C) relates to cytomegalovirus infection, and (H) to herpes simplex virus infections. Among the main abnormalities identified in neonates exposed to congenital infections are central nervous system (CNS) damage, microcephaly, hearing loss, and ophthalmological impairment, all requiring regular follow-up to monitor its progression. Protein changes such as mutations, post-translational modifications, abundance, structure, and function may indicate a pathological condition before the onset of the first symptoms, allowing early diagnosis and understanding of a particular disease or infection. The term "proteomics" is defined as the science that studies the proteome, which consists of the total protein content of a cell, tissue or organism in a given space and time, including post-translational modifications (PTMs) and interactions between proteins. Currently, quantitative bottom-up proteomic strategies allow rapid and high throughput characterization of complex biological mixtures. Investigating proteome modulation during host-pathogen interaction helps in elucidating the mechanisms of infection and in predicting disease progression. This "molecular battle" between host and pathogen is a key to identify drug targets and diagnostic markers. Here, we conducted a survey on proteomic techniques applied to congenital diseases classified in the terminology "TORCH", including toxoplasmosis, ZIKV, malaria, syphilis, human immunodeficiency virus (HIV), herpes simplex virus (HSV) and human cytomegalovirus (HCVM). We have highlighted proteins and/or protein complexes actively involved in the infection. Most of the proteomic studies reported have been performed in cell line models, and the evaluation of tissues (brain, muscle, and placenta) and biofluids (plasma, serum and urine) in animal models is still underexplored. Moreover, there are a plethora of studies focusing on the pathogen or the host without considering the triad mother-fetus-pathogen as a dynamic and interconnected system.

Proteomics analysis of blood plasma in HIV-infected patients with chronic kidney disease

BACKGROUND

Patients treated for human immunodeficiency virus (HIV) infection are prone to developing chronic kidney disease (CKD). Current methods used in assessing kidney function suffer inaccuracy in HIV-infected patients. This study aims to identify biomarkers that could complement existing methods of kidney assessment among HIV-infected subjects.

METHODS

Plasma protein profiling was performed for HIV patients with CKD presented with negative/trace proteinuria (non-proteinuric) (n = 8) and their matched non-CKD controls, using two-dimensional gel electrophoresis (2DE); selected protein candidates were identified using mass spectrometry. Subsequently, altered plasma abundance of protein candidates were verified using Western blotting in HIV-infected subjects with non-proteinuric CKD (n = 8), proteinuric CKD (n = 5), and their matched non-CKD controls, as well as in HIV-uninfected subjects with impaired kidney function (n = 3) and their matched controls.

RESULTS

Analysis of 2DE found significantly altered abundance of five protein candidates between HIV-infected patients with non-proteinuric CKD and without CKD: alpha-1-microglobulin (A1M), serum albumin (ALB), zinc-alpha-2-glycoprotein (AZGP1), haptoglobin (HP), and retinol binding protein (RBP4). Western blotting showed an increased abundance of A1M and HP in HIV-infected patients with non-proteinuric CKD compared to their non-CKD controls, whereas A1M, AZGP1, and RBP4 were significantly increased in HIV-infected patients with proteinuric CKD compared to their non-CKD controls. Such pattern was not found in HIV-uninfected subjects with impaired kidney function.

CONCLUSION

The data suggests four proteins that may be used as biomarkers of CKD in HIV-infected patients. Further validation in a larger cohort of HIV-infected patients is necessary for assessing the clinical use of these proposed biomarkers for CKD.

HIV-1 Nef and host proteome analysis: Current perspective

Proteome represents the set of proteins being produced by an organism at a given time. Comparative proteomic profiling of a healthy and diseased state is likely to reflect the dynamics of a disease process. Proteomic techniques are widely used to discover novel biomarkers and decipher mechanisms of HIV-1 pathogenesis. Proteomics is thus emerging as an indispensable tool of monitoring a disease process and intense interactions between HIV-1 and host. Nef is known to regulate various functions in the host to establish the state of infection. This review gives an overview of all proteomic studies done on HIV infection and HIV associated disorders including recent developments in Nef-host proteomic profiling. Here, we propose an emphasis on Nef based proteomic studies. We also discuss the future prospects and the technical and biological challenges involved in proteomic studies. Future studies with Nef related proteomic investigation are likely to identify more targets for diagnosis and therapy.

Spectrum of renal disease in HIV-infected children: report of five cases

There is a paucity of literature on renal diseases associated with HIV infection in Asian countries. Renal disease in HIV-infected children can involve the glomerulus, interstitium, tubules or blood vessels of the kidney. In this case series, five HIV-infected children with various forms of renal disease are reported. The renal pathology included HIV-associated nephropathy, collapsing focal segmental glomerulosclerosis without tubular changes, tubule-interstitial nephritis and minimal change disease (MCD). Case five fulfilled the classification criteria for childhood polyarteritis nodosa (PAN). It is important to screen all HIV-infected children for renal disease to enable detection at an early stage.

Genetic Susceptibility to Postdiarrheal Hemolytic-Uremic Syndrome After Shiga Toxin-Producing Escherichia coli Infection: A Centers for Disease Control and Prevention FoodNet Study

Background

Postdiarrheal hemolytic-uremic syndrome (D+HUS) following Shiga toxin-producing Escherichia coli (STEC) infection is a serious condition lacking specific treatment. Host immune dysregulation and genetic susceptibility to complement hyperactivation are implicated in non-STEC-related HUS. However, genetic susceptibility to D+HUS remains largely uncharacterized.

Methods

Patients with culture-confirmed STEC diarrhea, identified through the Centers for Disease Control and Prevention FoodNet surveillance system (2007-2012), were serotyped and classified by laboratory and/or clinical criteria as having suspected, probable, or confirmed D+HUS or as controls and underwent genotyping at 200 loci linked to nondiarrheal HUS or similar pathologies. Genetic associations with D+HUS were explored by multivariable regression, with adjustment for known risk factors.

Results

Of 641 enrollees with STEC O157:H7, 80 had suspected D+HUS (41 with probable and 32 with confirmed D+HUS). Twelve genes related to cytokine signaling, complement pathways, platelet function, pathogen recognition, iron transport, and endothelial function were associated with D+HUS in multivariable-adjusted analyses (P ≤ .05). Of 12 significant single-nucleotide polymorphisms (SNPs), 5 were associated with all levels of D+HUS (intergenic SNP rs10874639, TFRC rs3804141, EDN1 rs5370, GP1BA rs121908064, and B2M rs16966334), and 7 SNPs (6 non-complement related) were associated with confirmed D+HUS (all P < .05).

Conclusions

Polymorphisms in many non-complement-related genes may contribute to D+HUS susceptibility. These results require replication, but they suggest novel therapeutic targets in patients with D+HUS.

A review of renal disease in children with HIV infection

Human immunodeficiency virus (HIV) infection continues to be a leading cause of morbidity and mortality. HIV-infected individuals are now surviving for a relatively longer period and this is because of easy accessibility to antiretroviral therapy these days. As a result, chronic disease-related complications are now being recognized more often. Kidney disease in HIV-infected children can vary from glomerular to tubular-interstitial involvement. We searched the database to identify various kidney diseases seen in HIV-infected children. We describe the epidemiology, pathogenesis, pathology, clinical and laboratory manifestations, management and outcome of commonly seen kidney disease in HIV-infected children. We also provide a brief overview of toxicity of antiretroviral drugs seen in HIV-infected children. Kidney involvement in HIV-infected children may arise because of HIV infection per se, opportunistic infections, immune mediated injury and drug toxicity. HIV-associated nephropathy is perhaps the most common and most severe form of kidney disease. Proteinuria may be a cost-effective screening test in the long-term management of HIV-infected children, however, there are no definite recommendations for the same. Other important renal diseases are HIV immune complex kidney disease, thrombotic microangiopathy, interstitial nephritis and vasculitis.

Urinary Markers of Tubular Injury in HIV-Infected Patients

Renal disease is a common complication of HIV-infected patients, associated with increased risk of cardiovascular events, progression to AIDS, AIDS-defining illness, and mortality. Early and accurate identification of renal disease is therefore crucial to improve patient outcomes. The use of serum creatinine, along with proteinuria, to detect renal involvement is essentially to screen for markers of glomerular disease and may not be effective in detecting earlier stages of renal injury. Therefore, more sensitive and specific markers are needed in order to early identify HIV-infected patients at risk of renal disease. This review article summarizes some new and important urinary markers of tubular injury in HIV-infected patients and their clinical usefulness in the renal safety follow-up of TDF-treated patients.

The Basics of Bacteriuria: Strategies of Microbes for Persistence in Urine

Bacteriuria, the presence of bacteria in urine, is associated with asymptomatic, as well as symptomatic, urinary tract infection (UTI). Bacteriuria underpins some of the dynamics of microbial colonization of the urinary tract, and probably impacts the progression and persistence of infection in some individuals. Recent molecular discoveries in vitro have elucidated how some key bacterial traits can enable organisms to survive and grow in human urine as a means of microbial fitness adaptation for UTI. Several microbial characteristics that confer bacteruric potential have been identified including de novo synthesis of guanine, relative resistance to D-serine, and catabolism of malic acid. Microbial characteristics such as these are increasingly being defined through the use of synthetic human urine (SHU) in vitro as a model to mimic the in vivo environment that bacteria encounter in the bladder. There is considerable variation in the SHU model systems that have been used to study bacteriuria to date, and this influences the utility of these models. In this review, we discuss recent advances in our understanding of bacteruric potential with a focus on the specific mechanisms underlying traits that promote the growth of bacteria in urine. We also review the application of SHU in research studies modeling UTI and discuss the chemical makeup, and benefits and limitations that are encountered in utilizing SHU to study bacterial growth in urine in vitro.

Urinary biomarkers of kidney diseases in HIV-infected children

A significant number of children infected with the human immunodeficiency virus 1 (HIV-1) virus all over the world are at risk of developing renal diseases that could have a significant impact on their treatment and quality of life. It is necessary to identify children undergoing the early stages of these renal diseases, as well as the potential renal toxicity that could be caused by antiretroviral drugs, in order to prevent the development of cardiovascular complications and chronic renal failure. This article describes the most common renal diseases seen in HIV-infected children, as well as the value and limitations of the clinical markers that are currently being used to monitor their renal function and histological damage in a noninvasive manner. In addition, we discuss the progress made during the last 10 years in the discovery and validation of new renal biomarkers for HIV-infected children and young adults. Although significant progress has been made during the early phases of the biomarkers discovery, more work remains to be done to validate the new biomarkers in a large number of patients. The future looks promising, however, the new knowledge needs to be integrated and validated in the context of the clinical environment where these children are living.

Quantitative mass spectrometry of urinary biomarkers

The effectiveness of treatment of renal diseases is limited because the lack of diagnostic, prognostic and therapeutic markers. Despite the more than a decade of intensive investigation of urinary biomarkers, no new clinical biomarkers were approved. This is in part because the early expectations toward proteomics in biomarkers discovery were significantly higher than the capability of technology at the time. However, during the last decade, proteomic technology has made dramatic progress in both the hardware and software methods. In this review we are discussing modern quantitative methods of mass-spectrometry and providing several examples of their applications for discovery and validation of renal disease biomarkers. We are optimistic about future prospects for the development of novel of specific clinical urinary biomarkers.

Role of circulating fibroblast growth factor-2 in lipopolysaccharide-induced acute kidney injury in mice

Fibroblast growth factor-2 (FGF-2) is an angiogenic growth factor involved in renal growth and regeneration. Previous studies in rodents revealed that single intrarenal injections of FGF-2 improved the outcome of acute kidney injury (AKI). Septic children usually show elevated plasma levels of FGF-2, and are at risk of developing AKI. However, the role of circulating FGF-2 in the pathogenesis of AKI is not well understood. We have developed a mouse model to determine how FGF-2 released into the circulation modulates the outcome of AKI induced by lipopolysaccharide (LPS). Young FVB/N mice were infected with adenoviruses carrying a secreted form of human FGF-2 or control LacZ vectors. Subsequently, when the circulating levels of FGF-2 were similar to those seen in septic children, mice were injected with a non-lethal dose of LPS or control buffer. All mice injected with LPS developed hypotension and AKI, from which they recovered after 5 days. FGF-2 did not improve the outcome of AKI, and induced more significant renal proliferative and apoptotic changes during the recovery phase. These findings suggest that circulating FGF-2 may not necessarily prevent the development or improve the outcome of AKI. Moreover, the renal accumulation of FGF-2 might cause further renal damage.

Urinary hepcidin-25 and risk of acute kidney injury following cardiopulmonary bypass

BACKGROUND AND OBJECTIVES

Acute kidney injury (AKI) complicating cardiopulmonary bypass (CPB) results in increased morbidity and mortality. Urinary hepcidin-25 has been shown to be elevated in patients who do not develop AKI after CPB using semiquantitative mass spectrometry (SELDI TOF-MS). The goals of this study were to quantitatively validate these findings with ELISA and evaluate the diagnostic performance of hepcidin-25 for AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A nested, case-control analysis of urinary hepcidin-25 in AKI (n = 22) and non-AKI (n = 22) patients was conducted to validate the SELDI TOF-MS data at the following times: preoperatively; the start of CPB; 1 hour on CPB; on arrival to the intensive care unit; and postoperative days (POD) 1 and 3 to 5. The diagnostic performance of hepcidin-25 was then evaluated in the entire prospective observational cohort (n = 338) at POD 1. AKI was defined as Cr >50% from baseline, within 72 hours postoperatively.

RESULTS

Urinary hepcidin-25/Cr ratio was significantly elevated in all patients at POD 1 compared with baseline (P < 0.0005) and was also significantly elevated in non-AKI versus AKI patients at POD 1 (P < 0.0005). Increased log(10) hepcidin-25/Cr ratio was strongly associated with avoidance of AKI on univariate analysis. On multivariate analysis, the log(10) hepcidin-25/Cr ratio (P < 0.0001) was associated with avoidance of AKI with an area under the curve of 0.80, sensitivity 0.68, specificity 0.68, and negative predictive value 0.96.

CONCLUSIONS

Elevated urinary hepcidin-25 on POD 1 is a strong predictor of avoidance of AKI beyond postoperative day 1.

Is complement a culprit in infection-induced forms of haemolytic uraemic syndrome?

Haemolytic uraemic syndrome (HUS) accounts for the most common cause of childhood acute renal failure. Characterized by the classical triad of a microangiopathic haemolytic anaemia, thrombocytopaenia and acute renal failure, HUS occurs as a result of Shiga-toxin producing microbes in 90% of cases. The remaining 10% of cases represent a heterogeneous subgroup in which inherited and acquired forms of complement dysregulation have been described in up to 60%. Emerging evidence suggests that microbes associated with HUS exhibit interaction with the complement system. With the advent of improved genetic diagnosis, it is likely that certain cases of infection-induced HUS may be attributed to underlying defects in complement components. This review summarises the interplay between complement and infection in the pathogenesis of HUS.

Advances in our understanding of the pathogenesis of HIV-1 associated nephropathy in children

Childhood HIV-1 associated nephropathy (HIVAN) is a clinical and renal histological disease characterized by heavy proteinuria associated with focal and segmental glomerular sclerosis and/or mesangial hyperplasia in combination with microcystic tubular dilatation. These lesions lead to renal enlargement and rapid progression to kidney failure. Children of African ancestry have a unique susceptibility to developing HIVAN. It is estimated that approximately 300,000 HIV-infected children living in the sub-Saharan Africa could develop HIVAN if they do not receive appropriate antiretroviral therapy. This article discusses recent developments and controversies related to the pathogenesis of childhood HIVAN. The role of host genetic factors, including the newly identified variants in the APOL1 gene, is discussed in the context of previous studies that established the pathological paradigm for HIVAN, and our current understanding of the functional genomics analysis. Hopefully, these advances will provide new research opportunities to generate better treatments for children with HIVAN.

Urinary NGAL is a useful clinical biomarker of HIV-associated nephropathy

BACKGROUND

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is expressed by kidney tubules that are acutely damaged, but few studies have investigated the association of neutrophil gelatinase-associated lipocalin (NGAL) with different forms of chronic kidney disease (CKD). HIV-associated nephropathy (HIVAN) is a progressive form of CKD characterized by collapsing focal segmental glomerulosclerosis and microcytic tubular dilatation that typically leads to end-stage renal disease (ESRD).

METHODS

Previously, we reported that microcystic tubular dilatations specifically expressed NGAL RNA, implying that the detection of uNGAL protein could mark advanced HIVAN. To test this idea, we performed a comparative study of diverse proteinuric glomerulopathies in 25 patients who were HIV positive.

RESULTS

Eighteen patients had HIVAN and seven had other glomerulopathies (four membranoproliferative glomerulonephritis, one membranous glomerulonephritis, one amyloid and one malarial GN). HIVAN and non-HIVAN patients did not differ with respect to age, ethnicity, serum creatinine, estimated GFR, proteinuria or the prevalence of hypocomplementemia (6 versus 29%, P = 0.18), but HIVAN patients were less likely to have HCV infections. HIVAN patients expressed 4-fold higher levels of uNGAL than the patients with other glomerulopathies [387 ± 338 versus 94 ± 101 μg/g urine creatinine (uCr), P = 0.02]. A cutpoint of 121.5 μg uNGAL/g uCr demonstrated 94% sensitivity and 71% specificity for the diagnosis of HIVAN, with an area under the receiver operator characteristic curve of 0.88.

CONCLUSION

In summary, while HIVAN disease is currently diagnosed only by kidney biopsy, uNGAL can distinguish HIVAN from other proteinuric glomerulopathies in the HIV-infected patient, likely because of its specific expression from characteristic microcysts.

Recent developments in HIV-related kidney disease

Although kidney disease has been a recognized complication of HIV infection since the beginning of the HIV epidemic, its epidemiology, underlying causes and treatment have evolved in developed countries where HAART has been widely available. HIV-associated nephropathy and HIV immune complex-mediated kidney disease were the prominent renal diagnoses in the earlier period of the HIV epidemic. While HIV immune complex-mediated kidney disease remains a common finding among HIV-infected individuals with kidney disease, the incidence of HIV-associated nephropathy has been diminishing in developed countries. The role of the metabolic effects of long-term HAART exposure and nephrotoxicity of certain antiretroviral medications on the development and progression of chronic kidney disease is now of increasing concern. The long-term clinical implications of acute kidney injury among HIV-infected persons are increasingly recognized. Kidney disease in HIV-infected persons continues to be a major risk factor for morbidity and mortality in this patient population; therefore, early recognition and treatment of kidney disease are imperative in lessening the impact of kidney disease on the health of HIV-infected individuals. This review focuses on recent developments and ongoing challenges in the understanding, diagnosis and management of HIV-related kidney disease.

Host proteome research in HIV infection

Proteomics has been widely used in the last few years to look for new biomarkers and decipher the mechanism of HIV–host interaction. Herein, we review the recent developments of HIV/AIDS proteomic research, including the samples used in HIV/AIDS related research, the technologies used for proteomic study, the diagnosis biomarkers of HIV-associated disease especially HIV-associated neurocognitive impairment, the mechanisms of HIV–host interaction, HIV-associated dementia, substance abuse, and so on. In the end of this review, we also give some prospects about the limitation and future improvement of HIV/AIDS proteomic research.

Screening for chronic kidney disease in HIV-infected patients

With improved survival afforded by highly active antiretroviral therapy (HAART), CKD has emerged as one of the primary comorbid conditions affecting HIV-infected individuals. Although CKD in HIV-infected individuals is classically thought of as a consequence of advanced HIV infection such as in the case of HIV-associated nephropathy, several factors likely contribute to the development CKD in HIV infection. These factors include genetic predisposition, age-related decline in kidney function, HAART-related metabolic changes, exposure to multiple nephrotoxic medications, and concurrent conditions such as hepatitis C or illicit drug use. Similar to the general population, proteinuria and impaired kidney function are associated with faster progression to acquired immune deficiency syndrome and death. Given the prevalence and impact of kidney disease on the course of HIV infection and its management, current guidelines recommend screening all HIV-infected individuals for kidney disease. This review focuses on the current guidelines for kidney disease screening and discusses traditional as well as promising strategies for detecting CKD in this vulnerable population.

A urinary biomarker profile for children with HIV-associated renal diseases

Human immunodeficiency virus (HIV)-infected children are at risk of developing several types of renal diseases, including HIV-associated nephropathy (HIVAN), which is usually seen during late stages of infection in children with a high viral load. This disease is defined by the presence of proteinuria associated with mesangial hyperplasia and/or global-focal segmental glomerulosclerosis combined with microcystic transformation of the renal tubules. Because HIVAN can have an insidious clinical onset, renal biopsy is the only definitive way of establishing a diagnosis. Given the risk of performing this procedure in HIV-infected children with other AIDS-defining illness, we sought to identify informative biomarkers such as growth factors in the urine of 55 HIV-infected children that might be predictive of the extent and activity of the renal lesions characteristic of HIVAN. We found that the levels of epidermal growth factor were lower in the urine of children with renal disease, whereas levels of fibroblast growth factor-2 and metalloproteinase-2 were higher as compared with those levels in infected children without renal disease. Similar changes were observed in HIV-Tg26 mice correlating with the progression of renal disease in this model of HIVAN. Our findings suggest that this urinary growth factor profile may be useful in facilitating the diagnosis of HIV-infected children at risk of developing HIVAN when interpreted in the appropriate clinical setting.