Novel evidence on hepatitis C virus-associated glomerular disease

The Human Virome and Its Crosslink with Glomerulonephritis and IgA Nephropathy

The prokaryotic, viral, fungal, and parasitic microbiome exists in a highly intricate connection with the human host. In addition to eukaryotic viruses, due to the existence of various host bacteria, phages are widely spread throughout the human body. However, it is now evident that some viral community states, as opposed to others, are indicative of health and might be linked to undesirable outcomes for the human host. Members of the virome may collaborate with the human host to retain mutualistic functions in preserving human health. Evolutionary theories contend that a particular microbe's ubiquitous existence may signify a successful partnership with the host. In this Review, we present a survey of the field's work on the human virome and highlight the role of viruses in health and disease and the relationship of the virobiota with immune system control. Moreover, we will analyze virus involvement in glomerulonephritis and in IgA nephropathy, theorizing the molecular mechanisms that may be responsible for the crosslink with these renal diseases.

Role of fluid-phase complement system regulation in the development of hepatitis C virus-associated glomerulonephritis

OBJECTIVES

It is not known why only some hepatitis C virus (HCV) infected patients develop glomerulonephritis (GN). Therefore, we investigated the role of soluble complement regulators in the development of HCV associated GN.

METHODS

Patients with HCV associated GN who were admitted to our nephrology unit between July 2016 and July 2018 were recruited to the study (group 1). Two other age and sex matched groups were studied as control groups: patients with HCV without GN (group 2) and healthy HCV negative volunteers (group 3). There were 26 participants in each of the three groups at the end of the recruitment period. An assay of serum fluid-phase complement regulators was performed using enzyme linked immunosorbent assay technique. Three complement single nucleotide polymorphisms (SNPs) were analyzed using real time polymerase chain reaction (Taqman; thermo fisher scientific): rs2230199 and rs1047286 for complement 3 (C3) and rs800292 for complement factor H (CFH).

RESULTS

Serum levels of complement 4 binding protein (C4BP) were significantly lower in group 1 (median 70 ng/ml) than in groups 2 (median 88.8 ng/ml) and 3 (median 82.8 ng/ml) with p value of 0.007. The minor allele (allele A) of rs800292 for CFH was significantly higher in group 2 and group 3 (G 54% and A 46%) than in group 1 (G 73% and A 27%), p = 0.04.

CONCLUSIONS

Low C4BP levels are associated with GN in HCV infected patients. In addition, rs800292 SNP in CFH protects against GN in patients with HCV.

Inflammation and kidney involvement in human viral diseases caused by SARS-CoV-2, HIV, HCV and HBV

Inflammation is closely related to renal diseases. This is particularly true for renal diseases caused by infections as in viral diseases. In this review, we highlight the inflammatory mechanisms that underlie kidney dysfunction in SARS-CoV-2, human immunodeficiency (HIV), hepatitis C (HCV), and hepatitis B (HBV) infections. The pathophysiology of renal involvement in COVID-19 is complex, but kidney damage is frequent, and the prognosis is worse when it happens. Virus-like particles were demonstrated mostly in renal tubular epithelial cells and podocytes, which suggest that SARS-CoV-2 directly affects the kidneys. SARS-CoV-2 uses the angiotensin-converting enzyme 2 receptor, which is found in endothelial cells, to infect the human host cells. Critical patients with SARS-CoV-2-associated acute kidney injury (AKI) show an increase in inflammatory cytokines (IL-1β, IL-8, IFN-γ, TNF-α), known as cytokine storm that favors renal dysfunction by causing intrarenal inflammation, increased vascular permeability, volume depletion, thromboembolic events in microvasculature and persistent local inflammation. Besides AKI, SARS-CoV-2 can also cause glomerular disease, as other viral infections such as in HIV, HBV and HCV. HIV-infected patients present chronic inflammation that can lead to a number of renal diseases. Proinflammatory cytokines and TNF-induced apoptosis are some of the underlying mechanisms that may explain the virus-induced renal diseases that are here reviewed.

Efficacy and Safety of Long-Term Corticosteroid Monotherapy in 26 Cases of Nephrotic Syndrome with Biopsy-Proven Membranous Nephropathy Induced by Seronegative Hepatitis B Virus-Associated Glomerulonephritis

BACKGROUND

Hepatitis B virus-associated glomerulonephritis (HBV-GN) can occur in patients with negative HBV serological antigens. Little is known about the treatment of seronegative HBV-GN (sn HBV-GN). The aim of this prospective study was to evaluate the efficacy and safety of corticosteroids in the treatment of sn HBV-GN.

METHODS

Twenty-six patients with nephrotic syndrome induced by seronegative HBV-associated membranous nephropathy were enrolled. The patients were given methylprednisolone (0.8 mg/kg/day) for 12-24 weeks, tapered by a 2-mg reduction every 1-3 months. Patients were followed up for 6-36 months. Complete remission (CR) was defined as proteinuria <0.3 g/24 h. Partial remission (PR) was defined as proteinuria of 0.3-3.5 g/24 h that was reduced ≥50% of the baseline level.

RESULTS

The effective remission (including CR and PR) rates of nephrotic syndrome were 23.1%, 61.5%, 73.1%, 76.2%, 90.5%, and 81.0%, respectively, after 1, 3, 6, 12, 24, and 36 months. Nineteen patients achieved effective remission after 11.68 ± 7.15 months. The level of serum albumin improved from 24.34 ± 6.71 g/L at baseline to 39.61 ± 7.45 g/L at the 36th month significantly. After treatment, the level of serum Cr was similar to the baseline. Only 2 patients relapsed. The primary adverse reaction was infection. None of the patients showed evidence of HBV replication.

CONCLUSION

The long-term middle-dose corticosteroid therapy without antiviral drugs is effective and safe for membranous sn HBV-GN patients. For sn HBV-GN patients, the monitoring of HBV DNA and HBV markers in the serum is necessary during the corticosteroid monotherapy.

TRIAL REGISTRATION

The Chinese Clinical Trial Registry (ChiCTR1900022518).

Viral-Associated GN: Hepatitis C and HIV

Viruses are capable of inducing a wide spectrum of glomerular disorders that can be categorized on the basis of the duration of active viremia: acute, subacute, or chronic. The variable responses of the adaptive immune system to each time period of viral infection results mechanistically in different histologic forms of glomerular injury. The unique presence of a chronic viremic carrier state with either hepatitis C (HCV) or HIV has led to the opportunity to study in detail various pathogenic mechanisms of viral-induced glomerular injury, including direct viral infection of renal tissue and the development of circulating immune complexes composed of viral antigens that deposit along the glomerular basement membrane. Epidemiologic data show that approximately 25%-30% of all HIV patients are coinfected with HCV and 5%-10% of all HCV patients are coinfected with HIV. This situation can often lead to a challenging differential diagnosis when glomerular disease occurs in this dual-infected population and requires the clinician to be familiar with the clinical presentation, laboratory workup, and pathophysiology behind the development of renal disease for both HCV and HIV. Both of these viruses can be categorized under the new classification of infection-associated GN as opposed to being listed as causes of postinfectious GN as has previously been applied to them. Neither of these viruses lead to renal injury after a latent period of controlled and inactive viremia. The geneses of HCV- and HIV-associated glomerular diseases share a total dependence on the presence of active viral replication to sustain renal injury so the renal disease cannot be listed under "postinfectious" GN. With the new availability of direct-acting antivirals for HCV and more effective combined antiretroviral therapy for HIV, successful remission and even regression of glomerular lesions can be achieved if initiated at an early stage.

Hepatitis C and kidney disease: A narrative review

Hepatitis-C (HCV) infection can induce kidney injury, mostly due to formation of immune-complexes and cryoglobulins, and possibly to a direct cytopathic effect. It may cause acute kidney injury (AKI) as a part of systemic vasculitis, and augments the risk of AKI due to other etiologies. It is responsible for mesangiocapillary or membranous glomerulonephritis, and accelerates the progression of chronic kidney disease due to other causes. HCV infection increases cardiovascular and liver-related mortality in patients on regular dialysis. HCV-infected patients are at increased risk of acute post-transplant complications. Long-term graft survival is compromised by recurrent or de novo glomerulonephritis, or chronic transplant glomerulopathy. Patient survival is challenged by increased incidence of diabetes, sepsis, post-transplant lymphoproliferative disease, and liver failure. Effective and safe directly acting antiviral agents (DAAs) are currently available for treatment at different stages of kidney disease. However, the relative shortage of DAAs in countries where HCV is highly endemic imposes a need for treatment-prioritization, for which a scoring system is proposed in this review. It is concluded that the thoughtful use of DAAs, will result in a significant change in the epidemiology and clinical profiles of kidney disease, as well as improvement of dialysis and transplant outcomes, in endemic areas.

Glomerular Diseases Associated With Hepatitis B and C

Infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) are prevalent worldwide. In this review, we discuss the epidemiology, pathogenesis, clinical manifestations, and treatment of HBV- and HCV-related glomerulonephritis (GN). The most common histopathologic presentation of HBV-GN is HBV-associated membranous nephropathy, which usually manifests clinically with varying grades of proteinuria and microscopic hematuria. The pathogenesis is likely to be immune complex mediated; however, other host and viral factors have been implicated. The treatment of HBV-GN revolves around antiviral therapy. Various histologic types of glomerular diseases are reported in association with HCV infection, the most frequent being Type 1 membranoproliferative glomerulonephritis, usually in the context of Type 2 mixed cryoglobulinemia. The pathogenesis of HCV-GN can be attributed to glomerular deposition of cryoglobulins or noncryoglobulin-immune complexes. Cryoglobulins typically comprised immunoglobulin Mκ with rheumatoid factor activity. Clinically, patients may present with proteinuria, microscopic hematuria, hypertension, and acute nephritic and/or nephrotic syndrome. The treatment of HCV-GN, especially cryoglobulinemic membranoproliferative glomerulonephritis, encompasses various options including contemporary antiviral therapy with or without conventional and novel immunomodulatory agents.