Objectives: There is no correlation between alanine aminotransferase levels, viral load, and histologic findings at dialysis in patients with chronic hepatitis C virus infection. Identification of the severity of hepatitis C-related liver disease before transplant could provide valuable data about the risk for liver-related mortality after transplant. In this study, we aimed to identify the severity of liver disease in end-stage renal disease patients with chronic hepatitis C virus infection, the progression of hepatic histopathology after kidney transplant, and whether immunosuppressive therapy affected post­transplant viral replication and hepatic histology.

Materials and Methods: Antihepatitis C virus-positive kidney transplant recipients (45 patients) enrolled in the study. Liver biopsy was performed in 45 patients before and 16 patients after kidney transplant. Interferon was given to 28 of 45 patients before kidney transplant. Biopsy before and after kidney transplant was performed in 5 of 14 patients.

Results: Patients had higher viral load, with genotype 1 predominancy (91%). Sustained viral response was achieved in 14 of 28 patients (50%). The histopathologic features of 45 patients who had pretransplant liver biopsy were as follows: 22 patients had mild hepatocellular injury, 17 patients had mild chronic hepatitis, 5 patients had moderate chronic hepatitis, and 1 patient had serious hepatitis. Follow-up biopsy after kidney transplant (mean, 2 y) in 16 of 45 patients showed that 3 of 16 patients had mild hepatocellular injury, 4 of 16 patients had mild hepatitis, 6 of 16 patients had moderate hepatitis, 2 of 16 patients had serious hepatitis, and 1 patient had cirrhosis. Patients showed neither progression, regression, nor stable liver histology.

Conclusions: Even with worse genotype profiles, chronic hepatitis C virus infection has an indolent progression in patients with end-stage renal disease and kidney transplant. Follow-up biopsies of kidney transplant recipients show reasonable progression during the first 2 years.

Key words : End-stage renal disease, Hepatitis, Liver biopsy, Pathology

Introduction

Prevalence studies indicate that between 3.4% and 49% patients who are on maintenance hemodialysis are positive for antihepatitis C virus (HCV) in different regions of the world.^1,2 The prevalence of HCV infection is higher in kidney transplant recipients (11%-49%) than hemodialysis patients.³ Although previous studies with short-term follow-up have shown similar outcomes between HCV-positive and HCV-negative kidney transplant recipients, several studies have shown worse graft and patient survival in HCV-positive patients after transplant (follow-up, 10 and 20 y).^4,5 However, the survival advantage associated with transplant still is present in comparison with HCV-infected patients who have end-stage renal disease (ESRD) and are on hemodialysis.⁶

In dialysis patients with chronic HCV infection, serum aminotransferase levels are not reliable in determining disease activity and fibrosis severity.⁷ There is no correlation between alanine amino­transferase levels, viral load, and histologic findings in dialysis patients with chronic HCV infection.⁸ It is not routine in most transplant centers to perform liver biopsy and determine severity of liver disease in HCV-positive patients who are candidates for kidney transplant. However, histopathologic evaluation of the liver in HCV-positive kidney transplant candidates might increase accuracy of staging liver disease and improve patient selection. Patients with HCV infection are at increased risk for progressive liver disease, and HCV infection is an independent risk factor for death and graft loss.⁹

The progression of liver disease is slow and does not occur in all patients. Immunosuppressive protocols and other comorbid conditions could contribute to liver disease progression. Most mortality in HCV-positive kidney recipients is associated with cardiovascular disease and nonliver-related sepsis. Therefore, identification of the severity of HCV-related liver disease before transplant could provide valuable data about the risk of liver-related mortality after transplant.^10,11

In this study, we aimed to identify the severity of liver disease in ESRD patients who had chronic HCV infection, the progression of hepatic histopathology after kidney transplant, and whether immuno­suppressive therapy affected posttransplant viral replication and hepatic histology.

Materials and Methods

Patients
Anti-HCV-positive patients (83 patients) who were diagnosed as having chronic HCV infection, either by serology or histopathology, and had kidney transplant at Baskent University Ankara Hospital from 1982 to 2013 enrolled in the study. There were 45 of 83 patients (45%) who had liver biopsy before kidney transplant and 16 of 45 patients who had follow-up liver biopsies after kidney transplant. Liver histopathology was assessed according to modified Knodell classification. Patients were classified as having mild hepatocellular injury or mild chronic hepatitis with Histology Activity Index (HAI) from 0 to 6 and fibrosis 0 to 1; moderate chronic hepatitis with HAI 7 to 12 and fibrosis 2 to 4; or serious chronic hepatitis with HAI 13 to 18, fibrosis 5, and presence of cirrhosis. All data were obtained retrospectively from the patient medical files.

Inclusion criteria were patients having regular evaluation at our center and diagnosed as anti-HCV-positive ≥ 6 months before kidney transplant, serologically diagnosed patients who were positive for both anti-HCV and HCV RNA, or anti-HCV-positive and HCV RNA negative patients who had histopathologically proven chronic HCV infection (age, 20-70 years).

Exclusion criteria were patients with irregular studies, HCV RNA-negative patients with biopsy findings that were incompatible with chronic HCV infection, and patients who had alcohol abuse or drug addiction.

Assays
Serum anti-HCV-positive status was diagnosed with a microparticle enzyme assay (AxSYM HCV version, MEIA, Abbott, Abbott Park, IL, USA) and chemiluminescent microparticle assay (The Architect System, CMIA, Abbott). Serum HCV RNA was diagnosed with nested polymerase chain reaction (PCR) from 1994 to 2003, newer technology (LightCycler) from 2003 to 2005, and real-time PCR assay since 2005 (Serum HCV RNA 10-time PCR, Cobas Tachman 48 HCV, Roche Diagnostics).

Statistical analyses
Data evaluation was performed with statistical software (SPSS, Version 16.0, SPSS Inc., Chicago, IL, USA). Numeric data were reported as median (minimum-maximum) or mean ± standard deviation. Comparisons between groups were evaluated with Mann-Whitney test, Fisher exact test, chi-square test, Cox proportional hazards regression model, and Kaplan-Meier method. Statistical significance was defined by P ≤ .05.

Results

There were 45 kidney transplant patients with chronic HCV infection enrolled in the study, including 30 male (66.6%) and 15 female patients (33.3%) with median age 46 years (range, 26-69 y). All 45 patients had pretransplant liver biopsy, and 16 of 45 patients had liver biopsies before and after transplant. Posttransplant biopsies were performed 2 years after kidney transplant. There were 41 patients (91.1%) on hemodialysis, 1 patient had peritoneal dialysis, and 3 patients had both hemodialysis and peritoneal dialysis at different times (median time, 48 mo; range, 1-276 mo). The leading causes of ESRD were glomerulonephritis (20%), hypertension (8.8%), pyelonephritis (8.8%), and unknown (40%). There were 39 patients (86.6%) who had living-related kidney transplant and 6 of 45 patients who had deceased-donor kidney transplant. Patients were on combined immunosuppressive treatment with cyclosporine (86.7%), azathioprine (32.5%), mycophenolate mofetil (45.8%), tacrolimus (30.1%), sirolimus (21.7%), and mycophenolic acid (30.1%).

Genotype profile of the patients included 30 patients (66.6%) who were genotype 1b, 11 patients (24.4%) who were genotype 1a, and 4 patients who were genotype 4.

Median viral load before kidney transplant was 55 000 000 IU/mL (range, 0-98 000 000 IU/mL). There were 21 of 45 patients (46.6%) who were HCV RNA-negative during kidney transplant and 7 of 21 patients (30%) who remained HCV RNA-negative after kidney transplant; 14 of 21 patients (70%) became HCV RNA-positive after kidney transplant. Seroconversion to HCV RNA-positive after kidney transplant was significantly lower in patients who were on tacrolimus than other immunosuppressive regimens (P ≤ .01). However, higher viral load was associated with higher mortality caused by sepsis (P ≤ .008).

There were 30 patients who received interferon (IFN) monotherapy before kidney transplant, and 28 of 30 patients had long-term follow-up data. There were 10 patients who received treatment for median 6 months, and 20 patients received treatment > 12 months (median, 12 mo; range, 12-19 mo). No patients had antiviral treatment after kidney transplant. Sustained viral response (SVR) rates were calculated with 28 patients because 2 patients were lost to follow-up; 14 of 28 patients (50%) achieved SVR. During long-term follow-up, only 1 patient had relapsed. Graft survival was 7.8 ± 2.5 years.

The histopathologic evaluation in 45 patients who had pretransplant liver biopsy included 22 patients (48.8%) who had mild hepatocellular injury, 17 patients (37.7%) who had mild chronic hepatitis, 5 patients (11.1%) who had moderate chronic hepatitis, and 1 patient (2.2%) who had serious hepatitis. No patients were cirrhotic. In 16 of 45 patients who had follow-up biopsies after kidney transplant (mean, 2 y), 3 of 16 patients (18.7%) had mild hepatocellular injury, 4 of 16 patients (25%) had mild hepatitis, 6 of 16 patients (37.5%) had moderate hepatitis, 2 of 16 patients (12.5%) had serious hepatitis, and 1 patient (6.2%) had cirrhosis on the follow-up biopsies. The comparison of pretransplant and posttransplant biopsy results of 7 patients showed that moderate hepatitis in these patients progressed to serious hepatitis in 2 patients, remained stable in 3 patients, and regressed to mild hepatitis in 2 patients.

There were 26 of 28 patients who had IFN treatment and had pretransplant liver biopsies, and 13 of 26 patients also had posttransplant biopsies. In 5 of 26 patients who had mild hepatitis, follow-up biopsies showed that 3 of 5 patients progressed to moderate hepatitis, 2 patients remained stable, and 1 patient progressed to cirrhosis from serious hepatitis (Table 1).

There were 14 patients who achieved SVR after IFN treatment, including 6 patients who had pretransplant and 5 of 14 patients who had posttransplant liver biopsies. In 3 patients who were diagnosed as having mild hepatitis before kidney transplant and after kidney transplant, 1 patient regressed to mild hepatocellular injury and 2 patients progressed to moderate hepatitis. There were 3 patients who were diagnosed with moderate hepatitis before kidney transplant; 1 of these patients remained stable and 1 patient regressed to mild hepatitis after kidney transplant, and 1 patient had no follow-up biopsy (Table 2).

Discussion

Patients with HCV infection are generally considered as having increased risk for progressive liver disease. The HCV-infected ESRD patients have milder hepatic necroinflammation and fibrosis than nonuremic HCV patients. The reason for this difference is not fully understood, but several theories have been proposed to explain this generally more indolent course. These include the altered immunologic state and relatively low HCV viral load as a result of clearance of HCV RNA by dialysate and/or possible viral clearance by dialyzer surface membranes; in addition, cytokines such as IFN-α and hepatocyte growth factor and antiviral activity may play a role.^12,13 Long-term patient and graft survival rates are lower in anti-HCV-positive than anti-HCV-negative kidney transplant recipients.¹⁴

However, data are contradictory about whether or not the severity of underlying liver disease in patients with HCV has an effect on outcomes after kidney transplant. After kidney transplant, few HCV infected patients (4.3%) show progression to end-stage liver disease, and liver disease had no effect on overall patient and graft survival after mean follow-up 7.4 years.¹⁵ In a study that compared an immuno­competent control group with HCV-infected kidney transplant recipients, more rapid progression of liver fibrosis was observed in kidney transplant recipients.¹⁶ The rate of progression of liver fibrosis was similar between patients with HCV infection without kidney disease and HCV infected kidney transplant recipients.¹⁷ Another study examined the effects of liver fibrosis in pretransplant liver biopsy on patient survival in 58 patients who had chronic HCV and ESRD, including 10 patients with advanced fibrosis (METAVIR stages 3 or 4) who had kidney transplant; at 52 months after transplant, mortality was similar between patients who had advanced fibrosis (stages 3 and 4) and less-advanced fibrosis (stages 0, 1, and 2).¹⁸ However, some authors suggest that chronic liver disease increases mortality in patients with than without HCV after kidney transplant.^19,20

The course of liver histopathology after kidney transplant is not clear or easily predicted. In sequential biopsies every 3 to 4 years in 51 kidney transplant recipients, variable outcomes were reported including progression, stability, and improvement in liver fibrosis.²¹ The severity of pretransplant liver fibrosis and longer duration of posttransplant follow-up were associated with progression of liver fibrosis.¹⁷

In a large study with 207 patients who had liver biopsy before transplant, 44 patients had 51 follow-up liver biopsies at 5-year intervals, either while on the waiting list for a kidney or after kidney transplant.⁶ Despite many years of immuno­suppression, liver histology remained stable or improved in most rebiopsied transplant patients, but liver injury progressed more commonly in patients who remained on the waiting list; kidney transplant was associated with a survival advantage in HCV-infected kidney transplant recipients compared with patients who remained on dialysis.

In the present patients, the interval between 2 biopsies was short (2 y) and patient numbers were small, but we observed an indolent course and good prognosis for liver histology without major variations between the 2 biopsies. Therefore, immuno­suppressive therapy did not have a detrimental effect on liver histology in HCV-infected kidney transplant recipients.

The question about the effect of HCV RNA load or genotype on progression of liver fibrosis after kidney transplant remains unanswered. However, some authors did not observe such a correlation between these parameters.²² The present patient group mainly consisted of genotype 1 patients (91%) who had high viral load (median viral load before kidney transplant, 55 000 000 IU/mL). There were 21 of 45 patients (46.6%) who were HCV RNA-negative during kidney transplant; 7 of 21 patients (30%) remained HCV RNA-negative after kidney trans­plant, and 14 of 21 patients (70%) became HCV RNA-positive after kidney transplant. Although viremia increases after transplant, the progression of liver fibrosis may decrease.^17,21

The primary causes of mortality for kidney transplant recipients, either HCV-positive or negative, were sepsis, cardiovascular disease, and malignancy.²³ In the present patients, higher viral load was associated with higher mortality that was caused by sepsis (P ≤ .008).

Successful IFN treatment has favorable outcomes on liver histology in ESRD patients with HCV, and patients with an SVR have decreased liver histology progression after kidney transplant.²⁴ The present patient group had 50% SVR (14 of 28 patients) but pre- and posttransplant biopsy results were available for only 5 patients. These patients demonstrated either progression, regression, or stable liver histology. The patient number was not large enough for further analysis of the effect of successful IFN treatment on posttransplant liver histology. However, after median follow-up 2 years in HCV infected kidney transplant recipients, these patients had favorable outcomes, and this suggests that HCV infection is not a contraindication for performing kidney transplant.

Seroconversion to HCV RNA-positive after kidney transplant was significantly less frequent in patients who were on tacrolimus therapy than other immunosuppressive regimens (P ≤ .01), and we did not observe such an effect on patients who were on cyclosporine treatment. This finding was inconsistent with previous studies. Cyclosporine has inhibitory effects on HCV replication in vitro.²⁵ Although it was believed that tacrolimus did not have this property, a prospective study of 253 HCV-positive patients who underwent transplant showed that patients receiving cyclosporine or tacrolimus showed no significant differences in virologic and clinical outcomes.²⁶ In 71 HCV infected kidney transplant recipients who were on cyclosporine or tacrolimus, analysis of viral kinetics and liver fibrosis showed that HCV viral load was lower in patients treated with tacrolimus than cyclosporine, and this effect became negligible 3 months after transplant. The extent of liver fibrosis was similar in both groups of HCV infected patients and a control group of non-HCV-infected patients after kidney transplant.²⁷

In conclusion, even with worse genotype profiles, we believe that chronic HCV infection has an indolent progression in patients with ESRD and kidney transplant. Follow-up biopsies of kidney transplant recipients show reasonable progression during the first 2 years after transplant. Tacrolimus may have favorable effect on outcome in patients with HCV infection compared with other common immuno­suppressive drugs. Kidney transplant is a better option than hemodialysis for ESRD patients who have chronic HCV infection.

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