Diagnosis and natural history of HIV-associated nephropathy

Prevalence and predictors of long-term progression of chronic kidney disease in people with HIV in Ghana from 2003-2018

BACKGROUND

HIV is associated with an increased risk of progression to chronic kidney disease (CKD), and this risk is higher in people of West African descent than many other ethnicities. Our study assessed the rates of eGFR change and predictors of rapid eGFR progression in patients receiving antiretroviral therapy (ART), including tenofovir disoproxil fumarate (TDF), in central Ghana between 2003 and 2018.

METHODS

This single-centre retrospective study enrolled people with HIV (PWH) initiating ART in Ghana between 2003-2018. Demographics, hepatitis B (HBsAg) status, ART regimens and estimated glomerular filtration rate (eGFR) measurements were recorded, and analyses including multi-level model linear regression were performed to determine predictors of greater levels of eGFR decline and risk of rapid eGFR decline.

RESULTS

Six hundred and fifty-nine adult participants were included in the study with a median follow-up time of 6 years (IQR 3.6-8.9). 149 participants (22.6%) also had confirmed HBV co-infection. eGFR mean values were lowest at the point of diagnosis and highest on the second measurement taken; mean eGFR slowly decreased over subsequent measures thereafter. TDF use was associated with the highest mean rate of eGFR decline of all nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs) with a statistically significant greater annual decline of -1.08 mL/min/1.73m2/year (CI: -1.92, -0.24) compared with zidovudine. Nevirapine (-0.78mL /min/173m2/year; CI: -1.39, -0.17) and protease inhibitors (-1.55mL/mil/173m2/year; CI: -2.68, -0.41) were associated with greater eGFR declines compared with efavirenz. Negative HBsAg status was associated with greater eGFR decline compared with positive HBsAg status (-1.25mL/mil/173m2/year; CI 0.29. -2.20).

CONCLUSIONS

Increased rates of eGFR decline amongst PWH in Ghana were associated with TDF, nevirapine, and protease inhibitor use as well as negative HBsAg status. Additional research using mortality outcome data is needed to closely assess long-term predictors of eGFR decline in African populations.

Infection-Related Glomerulonephritis in Children and Adults

Infection-related glomerulonephritis is an immunologically mediated glomerular injury after an infection. Glomerulonephritis may occur with the infection or after a variable latent period. Poststreptococcal glomerulonephritis (PSGN) is the prototype of infection-related glomerulonephritis. The streptococcal antigens, nephritis-associated plasmin-like receptor and streptococcal exotoxin B, have emerged as major players in the pathogenesis of PSGN. Although PSGN is the most common infection-related glomerulonephritis in children, in adults, glomerulonephritis is secondary to bacteria such as staphylococci, viruses such as hepatitis C, and human immunodeficiency virus, and, rarely, parasitic infections. Supportive therapy is the mainstay of treatment in most infection-related glomerulonephritis. Treatment of the underlying infection with specific antibiotics and antiviral medications is indicated in some infections. Parasitic infections, although rare, may be associated with significant morbidity. Poststreptococcal glomerulonephritis is a self-limiting condition with a good prognosis. However, bacterial, viral, and parasitic infections may be associated with significant morbidity and long-term consequences. Epidemiologic studies are required to assess the global burden of infection-related glomerulonephritis. A better understanding of the pathogenesis of infection-related glomerulonephritis may unravel more treatment options and preventive strategies.

HBV-positive and HIV-positive organs in transplantation: A clinical guide for the hepatologist

Organ transplantation is a life-saving treatment for patients with end-stage organ disease, a severe condition associated with a high risk of waitlist mortality. It is primarily limited by a shortage of available organs. Maximising available donors can increase access to transplantation. Transplantation from donors positive for HBV and HIV has increased in many countries. However, antiviral therapies need to be readily available for recipients after transplantation to prevent possible reactivation of the virus following the administration of immunosuppressive therapies. Furthermore, the intentional transmission of a virus has practical, ethical, and clinical implications. In this review, we summarise the current research, focusing on grafts from donors positive for the HBV surface antigen, antibodies against the HBV core antigen, and HIV, to help hepatologists and physicians interested in transplantation to select the best antiviral and/or prophylactic regimens for after transplantation.

HIV-associated nephropathy: Protocol and rationale for an exploratory genotype-phenotype study in a sub-Saharan African population

BACKGROUND

HIV-positive persons of African descent are disproportionately affected by chronic kidney disease (CKD). Deterioration to end-stage kidney disease (ESKD) also occurs in this population at a higher frequency. There remains a lot to learn about the genetic susceptibility to CKD in HIV positive patients, and the pathophysiology of progression to ESKD.

OBJECTIVES

We will conduct an exploratory genotype-phenotype study in HIV-positive persons with CKD in Aminu Kano Teaching Hospital, Nigeria, to determine blood-based differential gene expression biomarkers in different kidney risk groups according to the KDIGO 2012 criteria.

METHODS

We will consecutively screen 150 HIV-positive adults (≥18 years of age) attending the HIV clinic of Aminu Kano Teaching Hospital, Kano, Nigeria, for CKD based on proteinuria and elevation of estimated glomerular filtration rate. Among these, two separate groups of 16 eligible participants each (n = 32) will be selected in the four (4) KDIGO 2012 kidney risk categories. The groups will be matched for age, sex, viral suppression level and antiretroviral (ARV) regimen. In the first group (n = 16), we will determine differential gene expression markers in peripheral blood mononuclear cells using mRNA-sequencing (RNA-Seq). We will validate the differential expression markers in the second group (n = 16) using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Using a systems-based approach, we will construct, visualize and analyze gene-gene interaction networks to determine the potential biological roles of identified differential expression markers based on published literature and publicly available databases.

RESULTS

Our exploratory study will provide valuable information on the potential roles of differential expression biomarkers in the pathophysiology of HIV-associated kidney disease by identifying novel biomarkers in different risk categories of CKD in a sub-Saharan African population. The results of this study will provide the basis for population-based genome-wide association studies to guide future personalized medicine approaches.

CONCLUSION

Validated biomarkers can be potential targets for the development of stage-specific therapeutic interventions, an essential paradigm in precision medicine.

Delayed urea differential enhancement CEST (dudeCEST)-MRI with T1 correction for monitoring renal urea handling

PURPOSE

We demonstrate a method of delayed urea differential enhancement CEST for probing urea recycling action of the kidney using expanded multi-pool Lorentzian fitting and apparent exchange-dependent relaxation compensation.

METHODS

T₁ correction of urea CEST contrast by apparent exchange-dependent relaxation was tested in phantoms. Nine mice were scanned at 7 Tesla following intraperitoneal injection of 2M 150 μL urea, and later saline. T₁ maps and Z-spectra were acquired before and 20 and 40 min postinjection. Z-spectra were fit to a 7-pool Lorentzian model for CEST quantification and compared to urea assay of kidney homogenate. Renal injury was induced by aristolochic acid in 7 mice, and the same scan protocol was performed.

RESULTS

Apparent exchange-dependent relaxation corrected for variable T₁ times in phantoms. Urea CEST contrast at +1 ppm increased significantly at both time points following urea injection in the inner medulla and papilla. When normalizing the postinjection urea CEST contrast to the corresponding baseline value, both urea and saline injection resulted in identical fold changes in urea CEST contrast. Urea assay of kidney homogenate showed a significant correlation to both apparent exchange-dependent relaxation (R² = 0.4687, P = .0017) and non-T₁ -corrected Lorentzian amplitudes (R² = 0.4964, P = .0011). Renal injury resulted in increased T₁ time in the cortex and reduced CEST contrast change upon urea and saline infusion.

CONCLUSION

Delayed urea enhancement following infusion can provide insight into renal urea handling. In addition, changes in CEST contrast at 1.0 ppm following saline infusion may provide insight into renal function.

Molecular Mechanisms of Injury in HIV-Associated Nephropathy

HIV-associated nephropathy (HIVAN) is an important cause of secondary focal glomerulosclerosis that occurs primarily in persons of African ancestry with advanced HIV disease. Although HIVAN is characterized by severe proteinuria and rapid progression to end stage renal disease without treatment, the phenotype is markedly attenuated by treatment with antiretroviral medications. HIV infection of glomerular and tubular epithelial cells and subsequent viral gene expression is a key contributor to HIVAN pathogenesis and the kidney can serve as reservoir for HIV strains that differ those in blood. HIV gene expression in renal epithelial cells leads to dysregulation of cellular pathways including cell cycle, inflammation, cell death, and cytoskeletal homeostasis. Polymorphisms in the APOL1 gene explain the marked predilection of HIVAN to occur in persons of African descent and HIVAN. Since HIVAN has the strongest association with APOL1 genotype of any of the APOL1-associated nephropathies, studies to determine the mechanisms by which HIV and APOL1 risk variants together promote kidney injury hold great promise to improve our understanding of the pathogenesis of APOL1-mediated kidney diseases.

Effect of Tenofovor Diproxil Fumarate on Renal Function and Urinalysis Abnormalities in HIV-Infected Cameroonian Adults

In Sub-Saharan Africa, the prevalence of HIV-associated kidney diseases is as high as 53.3%. Combined antiretroviral treatment (cART), especially tenofovir disoproxil fumarate (TDF), is known to be nephrotoxic. We undertook this cross-sectional study conducted in 2015 at the Regional Hospital Limbe in the Southwest Region of Cameroon to determine the prevalence of renal dysfunction and its correlates among treatment-experienced HIV-infected patients on TDF and treatment-naïve patients. In April 2016, a follow-up was performed on those who had been treatment-naïve and were started on cART after enrolment in the study. We compared 119 patients on TDF-containing regimens with 47 treatment-naïve patients. Proteinuria was significantly more prevalent, and creatinine was significantly higher among treatment-naïve patients than among those on treatment (52.2% versus 26.1%; P = 0.003 and P = 0.009, respectively). The proportion of patients with an estimated glomerular filtration rate (eGFR) < 60 mL/minute was significantly higher among treatment-naïve patients than among those on TDF treatment (40.4% versus 24.4%; P = 0.041). Treatment-naïve patients displayed an improvement in creatinine levels and eGFR after 6 months of treatment. To the best of our knowledge, this is the first study to investigate the impact of TDF on renal parameters in Cameroon. TDF appears to be safe and does not appear to be a significant cause of renal impairment. However, renal parameters should be monitored regularly, as recommended by the guidelines.

HIV associated kidney diseases: Clarifying concordance between renal failure in HIV infection and histopathologic manifestations at kidney biopsy

Patients with HIV infection have a wide spectrum of renal diseases. Some are known to be the direct effect of the viral infection while others are renal diseases that also occur in uninfected populations. HIV associated nephropathy (HIVAN) is considered to be a subtype of primary focal and segmental glomerulosclerosis that is distinct in HIV infected patients. It is more frequent in the African-American population and associated with mutations of the apolipoprotein L1 (APOL1) gene. HIV associated immune complex kidney disease (HIVICD) encompasses a spectrum of HIV associated renal diseases characterized by the presence of immune complex deposition within glomeruli. Thrombotic microangiopathy (TMA) is a complication of HIV infection that presents with hemolytic anemia, thrombocytopenia, and renal failure. TMA in HIV patients is associated with very high mortality. Lastly, the multitude of antiretroviral drugs used for treatment of HIV infections can result in nephrotoxicity. Although a kidney biopsy may not be the first line study for renal disease, knowledge of the different histopathologic features of HIV-associated and unassociated diseases is of paramount importance in the treatment and subsequent outcome of renal function in HIV infected patients. In this review we will describe the histopathologic features and discuss the pathophysiology of the entities previously named.

Tenofovir is associated with increased tubular proteinuria and asymptomatic renal tubular dysfunction in Ghana

BACKGROUND

HIV infection is associated with increased risk of renal dysfunction, including tubular dysfunction (TD) related to antiretroviral therapy (ART). Tenofovir disoproxil fumarate (TDF) is becoming available for ART in sub-Saharan Africa, although data on its long-term safety there is limited. We aimed to study the prevalence of HIV-associated renal dysfunction in Ghana and explore associations between proteinuria or TD and potential risk factors, including TDF use.

METHODS

A single-centre cross-sectional observational study of patients taking ART was undertaken. Creatinine clearance (CrCl) was calculated and proteinuria detected with dipsticks. Spot urinary albumin and protein:creatinine ratios (uACR/uPCR) were measured and further evidence of TD (defined as having two or more characteristic features) sought. Logistic regression analysis identified factors associated with proteinuria or TD.

RESULTS

In 330 patients, of whom 101 were taking TDF (median 20 months), the prevalence of CrCl < 60 ml/min/1.73 m(2), dipstick proteinuria and TD was 7 %, 37 % and 15 %. Factors associated with proteinuria were baseline CD4-count [aOR 0.86/100 cell increment (95 % CI, 0.74-0.99)] and TDF use [aOR 2.74 (95 % CI, 1.38-5.43)]. The only factor associated with TD was TDF use [aOR 3.43 (95 % CI, 1.10-10.69)]. In a subset with uPCR measurements, uPCRs were significantly higher in patients taking TDF than those on other drugs (10.8 vs. 5.7 mg/mmol, p < 0.001), and urinary albuin:protein ratios significantly lower (0.24 vs. 0.58, p < 0.001).

CONCLUSIONS

Both proteinuria and TD are common and associated with TDF use in Ghana. Further longitudinal studies to determine whether proteinuria, TD or TDF use are linked to progressive decline in renal function or other adverse outcomes are needed in Africa.

The transplantation of solid organs from HIV-positive donors to HIV-negative recipients: ethical implications

HIV-positive individuals have traditionally been barred from donating organs due to transmission concerns, but this barrier may soon be lifted in the USA in limited settings when recipients are also infected with HIV. Recipients of livers and kidneys with well-controlled HIV infection have been shown to have similar outcomes to those without HIV, erasing ethical concerns about poorly chosen beneficiaries of precious organs. But the question of whether HIV-negative patients should be disallowed from receiving an organ from an HIV-positive donor has not been adequately explored. In this essay, we will discuss the background to this scenario and the ethical implications of its adoption from the perspectives of autonomy, beneficence/non-maleficence and justice.

Differentiating HIV-associated nephropathy from antiretroviral drug-induced nephropathy: a clinical challenge

With the introduction of potent combination antiretroviral therapy (cART) into clinical practice, HIV-infected patients have garnered much benefit. However, kidney disease continues to be a potential complication in this group. Whereas HIV-associated nephropathy (HIVAN) was the major renal complication prior to cART, co-morbid diseases and adverse renal effects of various drugs, in particular cART, now complicate the landscape. Clinicians now must differentiate HIVAN from cART nephrotoxicity. While sometimes this is easy and relatively straightforward, often the clinician faces a difficult challenge distinguishing these two etiologies of kidney disease. This review will discuss HIVAN and cART-related kidney disease and review the clinical and laboratory data that may be useful in differentiating these processes. Often, however, kidney biopsy may be required to differentiate HIVAN from cART nephrotoxicity as well as other kidney lesions associated with concurrent co-morbidities, both infectious and non-infectious.

Predictors of resolution and persistence of renal laboratory abnormalities in pediatric HIV infection

BACKGROUND

Among human immunodeficiency virus (HIV)-infected youth, the role of renal disease (RD) and its management has become increasingly important as these children/adolescents mature into young adults. The identification of predictors of abnormal renal laboratory events (RLE) may be helpful in the management of their HIV infection and its associated renal complications.

METHODS

Data collected from HIV-infected youth followed for ≥ 48 months were analyzed to identify predictors of resolution versus persistence of RLE and determine the utility of RLE to predict the onset of RD. Analysis included descriptive and inferential methods using a multivariable extended Cox proportional hazards model.

RESULTS

Of the 1,874 at-risk children enrolled in the study, 428 (23 %) developed RLE, which persisted in 229 of these (54 %). CD4 percentages of <25 % [hazard ratio (HR) 0.63, p < 0.002) and an HIV viral load of >100,000 copies/ml (HR 0.31, p < 0.01) were associated with reduced rates of resolution, while in most cases exposure to highly active antiretroviral therapy (HAART)/nephrotoxic HAART prior to or subsequent to RLE were not. Persistence of RLE was 88 % sensitive for identifying new RD. Negative predictive values for RD were >95 % for both the at-risk cohort and those with RLE.

CONCLUSIONS

Advanced HIV disease predicted persistence of RLE in HIV-infected youth. Persistent RLE were useful for identifying RD.

Hyperglycemia enhances kidney cell injury in HIVAN through down-regulation of vitamin D receptors

In the present study, we evaluated the effect of short term hyperglycemia on renal lesions in a mouse model (Tg26) of HIV-associated nephropathy (HIVAN). Control and Tg26 mice in groups (n=6) were administered either normal saline (FVBN or Tg) or streptozotocin (FVBN+STZ or Tg26+STZ). After two weeks, biomarkers were collected and kidneys were harvested. FVBN+ STZ and Tg26+STZ displayed elevated serum glucose levels when compared to FVBN and Tg26 respectively. Tg26+STZ displayed elevated (P<0.05) blood urea nitrogen (BUN) levels (P<0.05) and enhanced (P<0.01) proteinuria when compared to Tg26. Tg26+STZ displayed enhanced (P<0.001) number of sclerotic glomeruli and microcysts vs. Tg26. Renal tissues of Tg26 displayed down regulation of vitamin D receptor (VDR) expression and enhanced Ang II production when compared to FVBN mice. Hyperglycemia exacerbated down regulation of VDR and production of Ang II in FVBN and Tg mice. Hyperglycemia increased kidney cell reactive oxygen species (ROS) production and oxidative DNA damage in both FVBN and Tg26 mice. In in vitro studies, HIV down regulated podocyte VDR expression and also enhanced renin angiotensin system activation. In addition, both glucose and HIV stimulated kidney cell ROS generation and DNA damage and compromised DNA repair; however, tempol (superoxide dismutase mimetic), losartan (Ang II blocker) and EB1089 (VDR agonist) provided protection against DNA damaging effects of glucose and HIV. These findings indicated that glucose activated the RAS and inflicted oxidative stress-mediated DNA damage via down regulation of kidney cell VDR expression in HIV milieu both in vivo and in vitro.

APOL1 risk variants enhance podocyte necrosis through compromising lysosomal membrane permeability

Development of higher rates of nondiabetic glomerulosclerosis (GS) in African Americans has been attributed to two coding sequence variants (G1 and G2) in the APOL1 gene. To date, the cellular function and the role of APOL1 variants (Vs) in GS are still unknown. In this study, we examined the effects of overexpressing wild-type (G0) and kidney disease risk variants (G1 and G2) of APOL1 in human podocytes using a lentivirus expression system. Interestingly, G0 inflicted podocyte injury only at a higher concentration; however, G1 and G2 promoted moderate podocyte injury at lower and higher concentrations. APOL1Vs expressing podocytes displayed diffuse distribution of both Lucifer yellow dye and cathepsin L as manifestations of enhanced lysosomal membrane permeability (LMP). Chloroquine attenuated the APOL1Vs-induced increase in podocyte injury, consistent with targeting lysosomes. The chloride channel blocker DIDS prevented APOL1Vs- induced injury, indicating a role for chloride influx in osmotic swelling of lysosomes. Direct exposure of noninfected podocytes with conditioned media from G1- and G2-expressing podocytes also induced injury, suggesting a contributory role of the secreted component of G1 and G2 as well. Adverse host factors (AHFs) such as hydrogen peroxide, hypoxia, TNF-α, and puromycin aminonucleoside augmented APOL1- and APOL1Vs-induced podocyte injury, while the effect of human immunodeficiency virus (HIV) on podocyte injury was overwhelming under conditions of APOLVs expression. We conclude that G0 and G1 and G2 APOL1 variants have the potential to induce podocyte injury in a manner which is further augmented by AHFs, with HIV infection being especially prominent.

Modulation of renin angiotensin system predominantly alters sclerotic phenotype of glomeruli in HIVAN

HIV-associated nephropathy (HIVAN) is a common complication of HIV-1 infection in patients with African ancestry in general and with APOL1 gene risk variants in particular. Although collapsing glomerulopathy is considered a hallmark of HIVAN, significant numbers of glomeruli in patients with HIVAN also display other variants of focal segmental glomerulosclerosis (FSGS). We propose that collapsed glomeruli as well as glomeruli with other variants of FSGS are manifestations of HIVAN and their prevalence depends on associated host factors. We explored the role of the renin-angiotensin system (RAS) in the manifestation of any specific glomerular phenotype in HIVAN. To evaluate the role of the RAS we have used a genetically engineered mouse model of HIVAN (Tg26) with two and four copies of angiotensinogen (Agt) gene (Tg26/Agt2 and Tg26/Agt4). In Tg26/Agt2, 1 out of 6 glomeruli exhibited sclerosed phenotype, whereas 1 out of 25 glomeruli displayed collapsed phenotype; on the other hand, in Tg26/Agt4, 1 out of 3 glomeruli exhibited sclerotic phenotype and only 1 out of 7 glomeruli showed collapsed phenotype. To inhibit the effect of RAS, Tg26/Agt2 were administered captopril, aliskiren, aliskiren plus captopril or aliskiren plus telmisartan by miniosmotic pumps for 4 weeks. In all experimental groups there was a significant reduction in percentage of sclerosed glomeruli and only minimal reduction in collapsed glomeruli compared to normal saline receiving Tg26/Agt2. These findings suggest that the manifestation of the sclerosed phenotype in HIVAN is predominantly dependent on activation of the RAS.

Renin angiotensin system modulates mTOR pathway through AT2R in HIVAN

Mammalian target of rapamycin (mTOR) has been reported to contribute to the development of HIV-associated nephropathy (HIVAN). We hypothesized that HIV may be activating renal tissue mTOR pathway through renin angiotensin system (RAS) via Angiotensin Receptor Type II receptor (AT2R). Renal tissues of Vpr transgenic and Tg26 (HIVAN) mice displayed enhanced phosphorylation of mTOR and p70S6K. Aliskiren, a renin inhibitor attenuated phosphorylation of both mTOR and p70S6K in renal tissues of HIVAN mice. Interestingly, Angiotensin Receptor Type I (AT1R) blockade did not modulate renal tissue phosphorylation of mTOR in HIVAN mice; on the other hand, AT2R blockade attenuated renal tissue phosphorylation of mTOR in HIVAN mice. In vitro studies, both renin and Ang II displayed enhanced mouse tubular cell (MTC) phosphorylation of p70S6K in a dose dependent manner. HIV/MTC also displayed enhanced phosphorylation of both mTOR and p70S6K; interestingly this effect of HIV was further enhanced by losartan (an AT1R blocker). On the other hand, AT2R blockade attenuated HIV-induced tubular cell phosphorylation of mTOR and p70S6K, whereas, AT2R agonist enhanced phosphorylation of mTOR and p70S6K. These findings indicate that HIV stimulates mTOR pathway in HIVAN through the activation of renin angiotensin system via AT2R.

Predictors of HIV-associated nephropathy

Renal disease accounts for significant morbidity and mortality in patients with HIV-1 infection. HIV-associated nephropathy (HIVAN) is an important cause of end stage renal disease in this population. Although multiple genetic, clinical, and laboratory characteristics such as Apolipoproetin-1 genetic polymorphism, high viral load, low CD-4 count, nephrotic range proteinuria, and increased renal echogenicity on ultrasound are predictive of HIVAN, kidney biopsy remains the gold standard to make the definitive diagnosis. Current treatment options for HIVAN include initiation of combined active antiretroviral therapy, blockade of the renin-angiotensin system, and steroids. In patients with progression of HIVAN, renal transplant should be pursued as long as their systemic HIV infection is controlled.

Role of inflammation in HIV-1 disease progression and prognosis

Inflammation and immune activation have been thrust to center stage in the understanding of HIV-1 disease pathogenesis and progression. Early work demonstrated that heightened levels of immune activation correlated with the extent of CD4 + T cell death in lymphoid tissue; however, this concept was not incorporated into the general view of disease pathogenesis. Since these early studies, the extension of life for patients on combination antiretroviral therapies (cART) has heralded a new era of non-AIDS-related diseases and incomplete restoration of immune function. The common link appears to be ongoing inflammation and immune activation. Thus, despite good control of viral loads, persons living with HIV (PLWH) remain at increased risk of inflammatory-associated complications such as cardiovascular disease and certain cancers. HIV-specific mechanisms as well as non-specific generalized responses to infection contribute to ongoing activation of the immune system. An early loss of gastrointestinal (GI) tract mucosal integrity, the pro-inflammatory cytokine milieu, co-infections and marked destruction of lymph node architecture are all factors contributing to the ongoing activation of the immune system as well as impaired immune recovery. It is becoming increasingly evident that the CD4 count and viral load do not provide a complete picture of the underlying state of the immune system. Heightened levels of inflammatory markers have been shown to predict increased mortality and other adverse events. Therefore, it will be important to incorporate these markers into management algorithms as soon as possible. This is particularly relevant in resource-poor countries where difficulties in cART roll-out and access are still encountered and, therefore, a mechanism for prioritizing individuals for therapy would be of value. This review will focus on the closely inter-related concepts of immune activation and inflammation. Both are broad concepts involving the interaction of various key players in the immune system. Importantly, immune activation promotes inflammation and thrombosis and similarly, inflammation and thrombosis induce immune activation. These concepts are thus intricately linked. Studies highlighting the potentially harmful effects of ongoing inflammation/immune activation are reviewed and the contributions of the GI tract "damage" and other co-infections such as CMV are explored. The complications resulting from persistent immune activation include enhanced CD4 + T cell death, lymphoid tissue destruction, and various pathologies related to chronic inflammation. Ultimately, we envision that the long-term management of the disease will incorporate both the identification and the amelioration of the potentially harmful effects of ongoing immune activation and inflammation.

mTOR plays a critical role in p53-induced oxidative kidney cell injury in HIVAN

Oxidative stress has been implicated to contribute to HIV-induced kidney cell injury; however, the role of p53, a modulator of oxidative stress, has not been evaluated in the development of HIV-associated nephropathy (HIVAN). We hypothesized that mammalian target of rapamycin (mTOR) may be critical for the induction of p53-mediated oxidative kidney cell injury in HIVAN. To test our hypothesis, we evaluated the effect of an mTOR inhibitor, rapamycin, on kidney cell p53 expression, downstream signaling, and kidney cell injury in both in vivo and in vitro studies. Inhibition of the mTOR pathway resulted in downregulation of renal tissue p53 expression, associated downstream signaling, and decreased number of sclerosed glomeruli, tubular microcysts, and apoptosed and 8-hydroxy deoxyguanosine (8-OHdG)-positive (+ve) cells in Tg26 mice. mTOR inhibition not only attenuated kidney cell expression of p66ShcA and phospho-p66ShcA but also reactivated the redox-sensitive stress response program in the form of enhanced expression of manganese superoxide dismutase (MnSOD) and catalase. In in vitro studies, the mTOR inhibitor also provided protection against HIV-induced podocyte apoptosis. Moreover, mTOR inhibition downregulated HIV-induced podocyte (HP/HIV) p53 expression. Since HP/HIV silenced for mTOR displayed a lack of expression of p53 as well as attenuated podocyte apoptosis, this suggests that mTOR is critical for kidney cell p53 activation and associated oxidative kidney cell injury in the HIV milieu.

Kidney disease in children and adolescents with perinatal HIV-1 infection

Introduction

Involvement of the kidney in children and adolescents with perinatal (HIV-1) infection can occur at any stage during the child's life with diverse diagnoses, ranging from acute kidney injury, childhood urinary tract infections (UTIs), electrolyte imbalances and drug-induced nephrotoxicity, to diseases of the glomerulus. The latter include various immune-mediated chronic kidney diseases (CKD) and HIV-associated nephropathy (HIVAN).

Discussion

The introduction of highly active anti-retroviral therapy (HAART) has dramatically reduced the incidence of HIVAN, once the commonest form of CKD in children of African descent living with HIV, and also altered its prognosis from eventual progression to end-stage kidney disease to one that is compatible with long-term survival. The impact of HAART on the outcome of other forms of kidney diseases seen in this population has not been as impressive. Increasingly important is nephrotoxicity secondary to the prolonged use of anti-retroviral agents, and the occurrence of co-morbid kidney disease unrelated to HIV infection or its treatment. Improved understanding of the molecular pathogenesis and genetics of kidney diseases associated with HIV will result in better screening, prevention and treatment efforts, as HIV specialists and nephrologists coordinate clinical care of these patients. Both haemodialysis (HD) and peritoneal dialysis (PD) are effective as renal replacement therapy in HIV-infected patients with end-stage kidney disease, with PD being preferred in resource-limited settings. Kidney transplantation, once contraindicated in this population, has now become the most effective renal replacement therapy, provided rigorous criteria are met. Given the attendant morbidity and mortality in HIV-infected children and adolescents with kidney disease, routine screening for kidney disease is recommended where resources permit.

Conclusions

This review focuses on the pathogenesis and genetics, clinical presentation and management of kidney disease in children and adolescents with perinatal HIV-1 infection.

Tenofovir treatment duration predicts proteinuria in a multiethnic United States Cohort of children and adolescents with perinatal HIV-1 infection

BACKGROUND

Tenofovir is associated with renal proximal tubule injury. Such toxicity has not been extensively studied in HIV-1-infected children, in whom tenofovir is increasingly used.

METHODS

History, urine and blood were collected at regular intervals from 448 children and adolescents with perinatal HIV-1 infection followed in the Pediatric HIV/AIDS Cohort study. Relationships between tenofovir use and proteinuria and chronic kidney disease (CKD) outcomes were examined using multivariable logistic regression models. Proteinuria was defined as at least one urine protein/creatinine ratio (uPCR) ≥ 0.2, and CKD as ≥ 2 sequential uPCR ≥ 0.2 or estimated glomerular filtration rates <60 mL/min/1.73 m with no subsequent resolution, or a clinical diagnosis not contradicted by a normal uPCR. Subjects with ≥ 2 uPCR <0.2, and no abnormal uPCR and eGFR comprised the comparison group.

RESULTS

Subjects were 47% male, 72% black, 24% Hispanic, with entry mean age (± standard deviation) of 11.5 ± 2.5 years. Proteinuria prevalence at entry, and annually during 3 years, ranged from 10.3% to 13.7%. The cumulative prevalence of proteinuria was 22% (94/434, 95% confidence interval: 18%-26%) and CKD 4.5% (20/448, 95% confidence interval: 2.7%-6.8%). Duration of tenofovir use was an independent predictor of proteinuria, with >3 years of exposure having the highest risk compared with no exposure (odds ratio: 2.53, 95% confidence interval: 1.23-5.22, overall P = 0.01). Overall, duration of tenofovir use did not significantly predict the presence of CKD.

CONCLUSIONS

Rates of proteinuria and CKD were lower than those seen in the pre-highly active antiretroviral therapy era. However, prolonged exposure to tenofovir increases risk of renal injury.

Rapamycin-induced modulation of miRNA expression is associated with amelioration of HIV-associated nephropathy (HIVAN)

Recent studies suggested that miRNAs are involved in the development of the pathogenesis of HIV-associated nephropathy (HIVAN). Rapamycin, a widely used mTOR inhibitor, has been demonstrated to slow down the progression of HIVAN. However, the role of miRNA in the regulation of these processes has not been investigated so far. In the current study, we have used a microarray-based approach in combination with real-time PCR to profile the miRNA expression patterns in rapamycin-treated HIVAN mice (Tg26). Our results demonstrated that 19 miRNAs belonging to 13 different families expressed differentially in renal tissues of rapamycin-receiving Tg26 mice when compared to Tg26 mice-receiving saline only. The patterns of miRNAs expression in rapamycin-receiving Tg26 mice took a reverse turn. These miRNAs were classified into 8 functional categories. In in vitro studies, we examined the expression of specific miRNAs in HIV-1 transduced human podocytes (HIV/HPs). HIV/HPs displayed attenuation of expression of miR-99a, -100a, -199a and miR-200, whereas, rapamycin inhibited this effect of HIV. These findings suggest that rapamycin-mediated up-regulation of specific miRNAs could contribute to amelioration of renal lesions in HIVAN mice.

Renal dysfunction in the setting of HIV/AIDS

Antiretroviral therapy has been immensely successful in reducing the incidence of opportunistic infections and death after HIV infection. This has resulted in heightened interest in noninfectious comorbidities including kidney disease. Although HIV-associated nephropathy, the most ominous kidney disease related to the direct effects of HIV, may be prevented and treated with antiretrovirals, kidney disease remains an important issue in this population. In addition to the common risk factors for kidney disease of diabetes mellitus and hypertension, HIV-infected individuals have a high prevalence of other risk factors, including hepatitis C and exposure to antiretrovirals and other medications. Therefore, the differential diagnosis is vast. Early identification (through efficient screening) and prompt treatment of kidney disease in HIV-infected individuals are critical to lead to better outcomes. This review focuses on clinical and epidemiological issues, treatment strategies (including dialysis and kidney transplantation), and recent advances among kidney disease in the HIV population.

MicroRNAs in HIV-associated nephropathy (HIVAN)

MicroRNAs (miRNAs) play a critical role in multiple biological and metabolic processes. Recent studies suggested that miRNAs are critical in the maintenance of glomerular homeostasis in both physiological and pathological states. However, the role of miRNAs in the pathogenesis of HIV-associated nephropathy (HIVAN) has not been studied. In the present study, we have used a microarray-based approach in combination with real-time PCR to profile the miRNA expression patterns in HIV-1 transgenic mice (Tg26). Our results showed that 13 miRNAs, which belong to 11 miRNA families, were downregulated in HIVAN when compared with control mice. These miRNAs were classified into 20 functional categories. In in vitro studies, we examined the expression of specific miRNAs in HIV-1 transduced human podocytes. Our results showed that HIV-1 downregulated miRNA expression, specifically of miR-200 and miR-33. These studies suggest that miRNAs contributed to the development of the proliferative phenotype of HIVAN. Further functional analysis of these miRNAs in HIVAN animal model will not only enhance understanding of the pathogenesis but would also lead to the development of therapeutic strategies for HIVAN patients.

Rapamycin-induced modulation of HIV gene transcription attenuates progression of HIVAN

HIV-associated nephropathy (HIVAN) is the manifestation of HIV gene expression by kidney cells in the presence of specific host factors. Recently, rapamycin (sirolimus) has been demonstrated to modulate the progression of HIVAN. We hypothesized that rapamycin would modulate the progression of HIVAN by attenuating HIV gene expression. To test our hypothesis, three weeks old Tg26 mice (n=6) were administered either vehicle or rapamycin (5 mg/kg, every other day, intraperitoneal) for eight weeks. At the end of the experimental period, the kidneys were harvested. In in vitro studies, human podocytes were transduced with either HIV-1 (NL4-3) or empty vector (EV), followed by treatment with either vehicle or rapamycin. Total RNA and proteins were extracted from renal tissues/cellular lysates and HIV gene transcription/translation was measured by real time PCR and Western blotting studies. Renal histological slides were graded for glomerular sclerosis and tubular dilatation with microcyst formation. Rapamycin attenuated both glomerular and tubular lesions in Tg26 mice. Rapamycin decreased transcription of HIV genes both in renal tissues as well as in HIV-1 transduced podocytes. Our data strongly indicate that HIV-1 long terminal repeat-mediated transcriptional activity was targeted by rapamycin. Rapamycin enhanced podocyte NF-κB and CREB activities but then it decreased AP-1 binding activity. Since expression of HIV genes by kidney cells has been demonstrated to be the key factor in the development HIVAN, it appears that rapamycin-induced altered transcription of HIV genes might have partly contributed to its disease modulating effects.

Nef interaction with actin compromises human podocyte actin cytoskeletal integrity

The HIV-1 accessory protein Nef is considered to play an important role in the development of a podocyte phenotype in HIV-1 associated nephropathy. We hypothesized that Nef may be altering the podocyte phenotype both structurally and functionally. To elucidate the involved mechanisms, podocyte proteins interacting with Nef were identified using GST pull down assay and yeast two hybrid assay. The GST pull down assay on protein extracts made from stable colonies of conditionally immortalized human podocytes expressing Nef (Nef/CIHP) displayed a band at 45 kD, which was identified as actin by mass spectrometry. Yeast two hybrid assay identified the following Nef-interacting proteins: syntrophin, filamin B, syntaxin, translational elongation factor 1, and zyxin. The Nef-actin and Nef-zyxin interactions were confirmed by co-localization studies on Nef/CIHP stable cell lines. The co-localization studies also showed that Nef/CIHP stable cell lines had a decreased number of actin filaments (stress fibers), displayed formation of lamellipodia, and increased number of podocyte projections (filopodia). Nef/CIHP displayed an enhanced cortical F-actin score index (P<0.001) and thus indicated a reorganization of F-actin in the cortical regions. Microarray analysis showed that Nef enhanced the expression of Rac1, syndecan-4, Rif, and CDC42 and attenuated the expression of syndecan-3 and syntenin. In addition, Nef/CIHPs displayed a diminished sphingomyelinase (ASMase) activity. Functionally, Nef/CIHPs displayed diminished attachment and enhanced detachment to their substrate. These findings indicate that Nef interaction with actin compromises the podocyte cytoskeleton integrity.

The prevalence of renal impairment among adults with early HIV disease in Blantyre, Malawi

We determined the prevalence of renal impairment and possible HIV-associated nephropathy (HIVAN) in adults with World Health Organization (WHO) stages I or II HIV, presenting to the antiretroviral therapy (ART) clinic in a central hospital in Malawi. We enrolled 526 ART-naïve subjects, 67% women, median age 34 (17-73) years and mean CD4 count 305 (3-993) cells/μL. Blood pressure, weight, urine dipstick and microscopy, CD4 cell count and serum creatinine were measured. Creatinine clearance (CrCL) was estimated using the Cockcroft-Gault equation. Possible HIVAN was diagnosed based on levels of proteinuria and CrCl. In all, 23.3% had proteinuria (≥ 1+). 57.4% had reduced CrCl (< 90 mL/minute): 18.8% had moderate (CrCl 30-59 mL/minute) and 2.2% severe (CrCl <30 mL/minute) renal dysfunction. Extrapolating from renal biopsy studies that confirmed HIVAN, the proportion of patients with HIVAN in our clinic ranges from 1.8-21.2%. We conclude that renal impairment was common, though rarely severe, among HIV-infected adults with clinically non-advanced HIV disease. Renal dysfunction has been demonstrated to be a risk factor for (early) mortality. These results are relevant for ART programmes, such as those in Malawi, where renal function is not routinely assessed.

[Risk factors related to renal disorders in HIV-1 infected patients]

INTRODUCTION

Renal disease has emerged as one of the primary comorbid conditions affecting HIV-infected patients, mainly because antiretroviral therapy has improved survival. This study aimed to detect risk factors possibly associated with altered renal function in HIV-infected patients.

METHODS

A cross-sectional study was conducted involving 254 HIV-infected patients attending an outpatient clinic at Santa Casa de Vitoria< They were interviewed and blood samples were collected for CD4 cell counts, HIV-1 viral load, glucose, lipids and creatinine measurements. Urine protein was evaluated in the first voiding urine sample. Glomerular filtration was estimated by simplified modified diet in renal disease (MDRD) and Cockcroft-Gault formulas.

RESULTS

One hundred and three (40.6%) patients presented some urinary abnormality, and proteinuria was the most common finding (46; 18.1% patients). Twenty-five (9.8%) patients showed estimated glomerular filtration below 60 ml/min/1.73 m² by MDRD. Multivariate logistic regression showed that low glomerular filtration was positively correlated with black race [OR 9.6 (IC95% 1.28-23.80)], arterial hypertension [OR 3.3 (IC95% 1.28-23.81)], age over fifty-one years-old [OR 3.3 (IC95%1.11-9.90)], proteinuria [OR 5.2 {IC95% 1.67-16.25}]; hematuria [OR 3.2 (1.12-9.29)] and negatively correlated with patients using zidovudine [OR 0.2 (0.04-0.78)].

CONCLUSIONS

Traditional risk factors for renal disease, such as black race, arterial hypertension and advancing age were correlated with low estimated glomerular filtration in the present patient sample.

mTOR as a multifunctional therapeutic target in HIV infection

Patients undergoing long-term highly active antiretroviral therapy treatment are probably at a higher risk of various HIV-related complications. Hyperactivation of The mammalian target of rapamycin (mTOR) has been found to contribute to dysregulated apoptosis and autophagy which determine CD4(+)-T-cell loss, impaired function of innate immunity and development of neurocognitive disorders. Dysregulated mTOR activation has also been shown to play a key part in the development of nephropathy and in the pathogenesis of HIV-associated malignancies. These studies strongly support a multifunctional key role for mTOR in the pathogenesis of HIV-related disorders and suggest that specific mTOR inhibitors could represent a novel approach for the prevention and treatment of these pathologies.

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.