Persistent cytomegalovirus in liver allografts with chronic rejection

Liver Transplantation in Recipients With a Positive Crossmatch: A Retrospective Single-Center Match-Pair Analysis

A positive crossmatch (XM+) is considered a contraindication to solid abdominal organ transplantation except liver transplantation (LT). Conflicting reports exist regarding the effects of XM+ on post-transplant outcomes. The goal of this retrospective single-center analysis is to evaluate the influence of XM+ on relevant outcome parameters such as survival, graft rejection, biliary and arterial complications. Forty-nine adult patients undergoing LT with a XM+ between 2002 and 2017 were included. XM+ LT recipients were matched 1:2 with crossmatch negative (XM-) LT recipients based on the balance of risk (BAR) score. Patient and graft survival were compared using Kaplan-Meier survival analysis and the log-rank test. Comparative analysis of clinical outcomes in XM+ and XM- groups were conducted. Patient and graft survival were similar in XM+ and XM- patients. Rejection episodes did not differ either. Recipients with a strong XM+ were more likely to develop a PCR+ CMV infection. A XM+ was not associated with a higher incidence of biliary or arterial complications. Donor age, cold ischemia time, PCR+ CMV infection and a rejection episode were associated with the occurrence of ischemic type biliary lesions. A XM+ has no effects on patient and graft survival or other relevant outcome parameters following LT.

Newer developments in viral hepatitis: Looking beyond hepatotropic viruses

Viral hepatitis in the entirety of its clinical spectrum is vast and most discussion are often restricted to hepatotropic viral infections, including hepatitis virus (A to E). With the advent of more advanced diagnostic techniques, it has now become possible to diagnose patients with non-hepatotropic viral infection in patients with hepatitis. Majority of these viruses belong to the Herpes family, with characteristic feature of latency. With the increase in the rate of liver transplantation globally, especially for the indication of acute hepatitis, it becomes even more relevant to identify non hepatotropic viral infection as the primary hepatic insult. Immunosuppression post-transplant is an established cause of reactivation of a number of viral infections that could then indirectly cause hepatic injury. Antiviral agents may be utilized for treatment of most of these infections, although data supporting their role is derived primarily from case reports. There are no current guidelines to manage patients suspected to have viral hepatitis secondary to non-hepatotropic viral infection, a gap that needs to be addressed. In this review article, the authors analyze the common non hepatotropic viral infections contributing to viral hepatitis, with emphasis on recent advances on diagnosis, management and role of liver transplantation.

Cytomegalovirus Hepatitis in Immunocompetent and Immunocompromised Hosts

Human cytomegalovirus (HCMV) infection is common and affects between 40-100% of the worldwide population. However, the majority of cases are asymptomatic and when severe disease occurs, it is usually restricted to immunocompromised patients. Liver involvement by HCMV differs significantly, accordingly to the immune status of the host. In immunocompromised patients, particularly liver transplant patients, it often causes clinically significant hepatitis. On the other hand, in immunocompetent patients, HCMV hepatitis requiring hospitalization is extremely rare. This review aims to appraise studies regarding the pathophysiology of HCMV hepatitis, including mechanisms of latency and reactivation and its contribution to disease development, clinical presentation, diagnostic modalities and treatment, with a focus on comparing different aspects between immunocompromised and immunocompetent hosts.

Cytomegalovirus Latency and Reactivation: An Intricate Interplay With the Host Immune Response

CMV is an ancient herpesvirus that has co-evolved with its host over millions of years. The 236 kbp genome encodes at least 165 genes, four non-coding RNAs and 14 miRNAs. Of the protein-coding genes, 43-44 are core replication genes common to all herpesviruses, while ~30 are unique to betaherpesviruses. Many CMV genes are involved in evading detection by the host immune response, and others have roles in cell tropism. CMV replicates systemically, and thus, has adapted to various biological niches within the host. Different biological niches may place competing demands on the virus, such that genes that are favorable in some contexts are unfavorable in others. The outcome of infection is dependent on the cell type. In fibroblasts, the virus replicates lytically to produce infectious virus. In other cell types, such as myeloid progenitor cells, there is an initial burst of lytic gene expression, which is subsequently silenced through epigenetic repression, leading to establishment of latency. Latently infected monocytes disseminate the virus to various organs. Latency is established through cell type specific mechanisms of transcriptional silencing. In contrast, reactivation is triggered through pathways activated by inflammation, infection, and injury that are common to many cell types, as well as differentiation of myeloid cells to dendritic cells. Thus, CMV has evolved a complex relationship with the host immune response, in which it exploits cell type specific mechanisms of gene regulation to establish latency and to disseminate infection systemically, and also uses the inflammatory response to infection as an early warning system which allows the virus to escape from situations in which its survival is threatened, either by cellular damage or infection of the host with another pathogen. Spontaneous reactivation induced by cellular aging/damage may explain why extensive expression of lytic genes has been observed in recent studies using highly sensitive transcriptome analyses of cells from latently infected individuals. Recent studies with animal models highlight the potential for harnessing the host immune response to blunt cellular injury induced by organ transplantation, and thus, prevent reactivation of CMV and its sequelae.

Bile Acids Act as Soluble Host Restriction Factors Limiting Cytomegalovirus Replication in Hepatocytes

The liver constitutes a prime site of cytomegalovirus (CMV) replication and latency. Hepatocytes produce, secrete, and recycle a chemically diverse set of bile acids, with the result that interactions between bile acids and cytomegalovirus inevitably occur. Here we determined the impact of naturally occurring bile acids on mouse CMV (MCMV) replication. In primary mouse hepatocytes, physiological concentrations of taurochenodeoxycholic acid (TCDC), glycochenodeoxycholic acid, and to a lesser extent taurocholic acid significantly reduced MCMV-induced gene expression and diminished the generation of virus progeny, while several other bile acids did not exert antiviral effects. The anticytomegalovirus activity required active import of bile acids via the sodium-taurocholate-cotransporting polypeptide (NTCP) and was consistently observed in hepatocytes but not in fibroblasts. Under conditions in which alpha interferon (IFN-α) lacks antiviral activity, physiological TCDC concentrations were similarly effective as IFN-γ. A detailed investigation of distinct steps of the viral life cycle revealed that TCDC deregulates viral transcription and diminishes global translation in infected cells.

IMPORTANCE

Cytomegaloviruses are members of the Betaherpesvirinae subfamily. Primary infection leads to latency, from which cytomegaloviruses can reactivate under immunocompromised conditions and cause severe disease manifestations, including hepatitis. The present study describes an unanticipated antiviral activity of conjugated bile acids on MCMV replication in hepatocytes. Bile acids negatively influence viral transcription and exhibit a global effect on translation. Our data identify bile acids as site-specific soluble host restriction factors against MCMV, which may allow rational design of anticytomegalovirus drugs using bile acids as lead compounds.

Prognostic factors for the evolution and reversibility of chronic rejection in pediatric liver transplantation

OBJECTIVE

Chronic rejection remains a major cause of graft failure with indication for re-transplantation. The incidence of chronic rejection remains high in the pediatric population. Although several risk factors have been implicated in adults, the prognostic factors for the evolution and reversibility of chronic rejection in pediatric liver transplantation are not known. Hence, the current study aimed to determine the factors involved in the progression or reversibility of pediatric chronic rejection by evaluating a series of chronic rejection cases following liver transplantation.

METHODS

Chronic rejection cases were identified by performing liver biopsies on patients based on clinical suspicion. Treatment included maintaining high levels of tacrolimus and the introduction of mofetil mycophenolate. The children were divided into 2 groups: those with favorable outcomes and those with adverse outcomes. Multivariate analysis was performed to identify potential risk factors in these groups.

RESULTS

Among 537 children subjected to liver transplantation, chronic rejection occurred in 29 patients (5.4%). In 10 patients (10/29, 34.5%), remission of chronic rejection was achieved with immunosuppression (favorable outcomes group). In the remaining 19 patients (19/29, 65.5%), rejection could not be controlled (adverse outcomes group) and resulted in re-transplantation (7 patients, 24.1%) or death (12 patients, 41.4%). Statistical analysis showed that the presence of ductopenia was associated with worse outcomes (risk ratio=2.08, p=0.01).

CONCLUSION

The presence of ductopenia is associated with poor prognosis in pediatric patients with chronic graft rejection.

Abnormal Localization of STK17A in Bile Canaliculi in Liver Allografts: An Early Sign of Chronic Rejection

The biological significance of STK17A, a serine/threonine kinase, in the liver is not known. We analyzed STK17A expression in HepG2 cells and human liver tissue. Accordingly, we investigated whether STK17A could help in identifying earlier changes during the evolution of chronic rejection (CR) after liver transplantation. RT-PCR and immunofluorescence were used to analyze STK17A expression in HepG2 cells. Antibody microarray was performed using human liver samples from CR and healthy donors. Immunohistochemistry was used to verify the clinical utility of STK17A on sequential biopsies for the subsequent development of CR. A novel short isoform of STK17A was found in HepG2 cells. STK17A was localized in the nuclei and bile canaliculi in HepG2 cells and human livers. Microarray of STK17A revealed its decrease in failed liver allografts by CR. During the evolution of CR, the staining pattern of bile canalicular STK17A gradually changed from diffuse linear to focal intermittent. The focal intermittent staining pattern was observed before the definite diagnosis of CR. In conclusion, the present study was the first to find localization of STK17A in normal bile canaliculi. Abnormal expression and localization of STK17A were associated with CR of liver allografts since the early stage of the rejection process.

Delayed-onset cytomegalovirus disease coded during hospital readmission in a multicenter, retrospective cohort of liver transplant recipients

Delayed-onset cytomegalovirus (CMV) disease can occur among liver transplant recipients after CMV prophylaxis is stopped. We hypothesized that delayed-onset CMV disease (>100 days after transplant) occurs more commonly than early-onset CMV disease and is associated with clinical sepsis and death. Using 2004-2010 International Classification of Diseases, Ninth Revision, Clinical Modification billing data from 4 Healthcare Cost and Utilization Project state inpatient databases, we assembled a large and more representative cohort of 7229 adult liver transplant recipients from 26 transplant centers, and we identified demographics, comorbidities, CMV disease, and clinical sepsis coded during readmission and inpatient death. Multivariate analysis was performed with Cox proportional hazards models. Delayed-onset CMV disease occurred in 4.3% (n = 309), whereas early-onset CMV disease occurred in 2% (n = 142). Delayed-onset CMV disease was associated with previous transplant failure or rejection [adjusted hazard ratio (aHR), 1.4; 95% confidence interval (CI), 1.1-1.7]. Clinical sepsis > 100 days after transplant was associated with previous CMV disease (aHR, 1.3; 95% CI; 1.0-1.7), previous transplant failure or rejection (aHR, 2.1; 95% CI; 1.8-2.4), female sex (aHR, 1.3; 95% CI; 1.1-1.5), and several comorbidities. Death > 100 days after transplant was associated with delayed-onset CMV disease (aHR, 2.0; 95% CI; 1.6-2.6), transplant failure or rejection (aHR, 4.3; 95% CI; 3.4-5.5), increasing age by decade (aHR, 1.1; 95% CI; 1.0-1.2), and some comorbidities. In conclusion, delayed-onset CMV disease is more common than early-onset CMV disease among liver transplant recipients. Previous CMV disease may be a risk factor for clinical sepsis > 100 days after transplant, and delayed-onset CMV disease may be a risk factor for death > 100 days after transplant.

Procalcitonin for differential diagnosis of graft rejection and infection in patients with heart and/or lung grafts

OBJECTIVES

Investigation of the reliability of Procalcitonin (PCT) for differential diagnosis of acute rejections and non-viral infections in heart and lung transplanted patients.

DESIGN

Retrospective study.

SETTING

Transplant intensive care unit (ICU) at a university hospital.

PATIENTS

57 heart, 18 lung and 3 heart-lung transplant patients.

MEASUREMENTS

PCT was measured in plasma samples of heart and lung transplanted patients using a commercial immuno-luminescence assay and was compared with values of C-reactive protein (CRP) and leukocytes (WBC).

RESULTS

PCT was elevated in patients suffering from bacterial and fungal infections. The magnitude of values was clearly associated with the severity of the infection. Rejections and viral infections did not interfere with the PCT release.

CONCLUSION

PCT is a reliable predictor with discriminating power for non-viral systemic infections in patients after heart and/or lung transplantation. PCT allows an early differential diagnosis between rejection (AR) and bacterial/fungal infection (IF) and thus a rapid and focused therapeutic intervention. It avoids unnecessary antibiotic treatment which could be toxic for the graft itself in patients with rejection only. PCT provides vital information early to clinicians and allows them to improve the management of bacterial/fungal infections in immunocompromized transplant patients. PCT thus facilitates and improves the outcome of survival rate and the quality of life in the postoperative period of patients with heart and/or lung grafts.

Procalcitonin for differential diagnosis of graft rejection and infection in patients with heart and/or lung grafts

OBJECTIVES

Investigation of the reliability of Procalcitonin (PCT) for differential diagnosis of acute rejections and non-viral infections in heart and lung transplanted patients.

DESIGN

Retrospective study.

SETTING

Transplant intensive care unit (ICU) at a university hospital.

PATIENTS

57 heart, 18 lung and 3 heart-lung transplant patients.

MEASUREMENTS

PCT was measured in plasma samples of heart and lung transplanted patients using a commercial immuno-luminescence assay and was compared with values of C-reactive protein (CRP) and leukocytes (WBC).

RESULTS

PCT was elevated in patients suffering from bacterial and fungal infections. The magnitude of values was clearly associated with the severity of the infection. Rejections and viral infections did not interfere with the PCT release.

CONCLUSION

PCT is a reliable predictor with discriminating power for non-viral systemic infections in patients after heart and/or lung transplantation. PCT allows an early differential diagnosis between rejection (AR) and bacterial/fungal infection (IF) and thus a rapid and focused therapeutic intervention. It avoids unnecessary antibiotic treatment which could be toxic for the graft itself in patients with rejection only. PCT provides vital information early to clinicians and allows them to improve the management of bacterial/fungal infections in immunocompromized transplant patients. PCT thus facilitates and improves the outcome of survival rate and the quality of life in the postoperative period of patients with heart and/or lung grafts.

Immunobiology of human cytomegalovirus: from bench to bedside

SUMMARY

Following primary infection, human cytomegalovirus (HCMV) establishes lifelong latency and periodically reactivates without causing symptoms in healthy individuals. In the absence of an adequate host-derived immune response, this fine balance of permitting viral reactivation without causing pathogenesis is disrupted, and HCMV can subsequently cause invasive disease and an array of damaging indirect immunological effects. Over the last decade, our knowledge of the immune response to HCMV infection in healthy virus carriers and diseased individuals has allowed us to translate these findings to develop better diagnostic tools and therapeutic strategies. The application of these emerging technologies in the clinical setting is likely to provide opportunities for better management of patients with HCMV-associated diseases.

Altered levels of CC chemokines during pulmonary CMV predict BOS and mortality post-lung transplantation

Pulmonary CMV infection (CMVI) and disease (CMVD) is associated with reduced long-term survival post-lung transplantation, however, the specific biologic mechanisms remain unclear. We have demonstrated a role of CC chemokines during lung allograft dysfunction. Based on these findings, we hypothesized that pulmonary CMV upregulates the expression of multiple CC chemokines that leads to allograft dysfunction and decreased long-term survival. We performed a nested case control study in lung transplant recipients to investigate alterations in CC chemokine biology during pulmonary CMV. Levels of CC chemokines were measured in bronchoalveolar lavage fluid (BALF) from recipients with CMVI (n = 33), CMVD (n = 6), and in healthy lung transplant controls (n = 33). We found a trend toward increased levels of MIP-1alpha/CCL3 during pulmonary CMVI. Levels of MCP-1/CCL2 and RANTES/CCL5 were significantly elevated during pulmonary CMV. Interestingly, elevated levels of CCL3 in BALF were protective with regards to survival. Importantly, elevated levels of CCL2 in BALF predicted the development of BOS, while elevated levels of CCL5 in BALF predicted an increase in mortality post-lung transplant. Altered levels of specific CC chemokines during pulmonary CMV are associated with future clinical outcomes. These results suggest a possible utility of BALF CC chemokines as biomarkers for guiding risk assessment during pulmonary CMV post-lung transplantation.

Persistent cytomegalovirus infection in kidney allografts is associated with inferior graft function and survival

The long-term effects of cytomegalovirus (CMV) infections on kidney allografts are unknown. We examined the impact of persistent intragraft CMV infection on long-term kidney allograft function and survival. CMV was diagnosed in 82/172 renal transplant recipients by antigenemia test and viral cultures. Biopsies from 48 of 82 patients taken after CMV infection and from 15 patients with no previous CMV infection detected were available for the immunohistochemical demonstration of CMV antigens and DNA hybridization in situ. Five-year follow-up data from these 63 patients were analysed. In 17 patients, CMV antigens and/or DNA persisted in the biopsy >2 months after the last positive finding in blood or urine. Patients with persistent intragraft CMV had reduced graft survival (P = 0.041) and Cox regression analysis showed persistent CMV as a risk factor for reduced graft survival (RR: 3.5). Recipients with persistent intragraft CMV had reduced creatinine clearance 1 and 2 years after transplantation (P = 0.007) and in multivariate logistic regression analyses including several potential pre- and posttransplant risk factors, persistent CMV was an independent risk factor for lower clearance at 1 and 2 years (OR: 4.4 and 4.9). Our novel findings show that persistent intragraft CMV infection was associated with reduced kidney allograft function and survival.

Cytomegalovirus infection of the liver transplant: virological, histological, immunological, and clinical observations

The most common organ-specific manifestation of cytomegalovirus (CMV) infection after liver transplantation is hepatitis. Here we retrospectively describe the detailed virological, histological, immunological, and clinical findings associated with CMV infection in 229 consecutive adult liver transplantation patients. CMV infection was diagnosed by pp65 antigenemia. From 439 liver biopsies, CMV antigens were demonstrated by immunohistochemistry and CMV DNA by hybridization. The Banff criteria were used for histology. The expression of various adhesion molecules (intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1], endothelial leukocyte adhesion molecule-1 [ELAM-1]), their ligands (leukocyte function antigen-1 [LFA-1], very late antigen-4 [VLA-4], Sialyl-LewisX-molecule [SLeX]), and lymphoid activation markers (major histocompatibility complex [MHC] Class II, interleukin-2-receptor [IL-2R]) was demonstrated by immunohistochemistry. CMV infection of the transplant occurred in 26 patients (11% of all 229 patients and 17% of the 151 patients with liver biopsy). The incidence was higher among seronegative (26%) than in seropositive recipients (9%), but most cases 18/26 (70%) were reactivations. The CMV pp65 antigenemia levels were usually high in primary infections (893+/-1069, range 50-3000 pp65+cells), but varied widely in reactivations (388+/-740, range 3-3000). The histological Banff score was slightly increased (2.3+/-0.9). Microabscesses, lymphocytic infiltration, Kupffer cell reaction, and parenchymal alterations were common but viral inclusions rare. CMV significantly (P<0.05) increased ICAM-1 and VCAM-1 expression and the number of LFA-1, VLA-4, and Class II-positive lymphocytes in the graft. All CMV infections were successfully treated with antivirals. Intragraft CMV infection had no influence on the long-term outcome, but biliary complications were common. In conclusion, CMV infection of the liver transplant occurred both in primary infection and in reactivation, and also in the cases with low pp65 antigenemia levels. Microabscesses and other histological alterations were common but viral inclusions rare. Increased adhesion molecule expression was associated with lymphocyte infiltration. Successfully treated CMV hepatitis had no influence on the long-term clinical outcome.

Post-transplant reactivation of hepatitis C virus: lymphocyte infiltration and the expression of adhesion molecules and their ligands in liver allografts

Hepatitis C virus (HCV) recurrence after liver transplantation has been associated with chronic rejection. Biopsies from 10 patients with post-transplant HCV were examined for expression of adhesion molecules ICAM-1, VCAM-1, and ELAM-1, number of lymphocytes positive for their ligands LFA-1, VLA-4, and SLeX, and activation markers MHC class II antigens and IL2-R by immunohistochemistry. The phenotypes of the graft-infiltrating lymphocytes were determined. Results were compared to those for patients with normal graft function or rejection. Five recipients with HCV reactivation and one with de novo HCV had a biopsy available showing induction of ICAM-1 in sinusoidal endothelium (p<0.05) and hepatocytes (p<0.01), and Class II antigens in hepatocytes (p<0.01), compared to normal controls. Lymphocytes in the graft infiltrate expressed LFA-1, VLA-4, and Class II antigens, but IL2-R was not significantly expressed. CD3+, CD4+, and CD8+ cells were observed. In our study, HCV recurrence was not associated with acute or chronic rejection, and the inflammation was due to the viral infection.

Replicative senescence of biliary epithelial cells precedes bile duct loss in chronic liver allograft rejection: increased expression of p21(WAF1/Cip1) as a disease marker and the influence of immunosuppressive drugs

Early chronic liver allograft rejection (CR) is characterized by distinctive cytological changes in biliary epithelial cells (BECs) that resemble cellular senescence, in vitro, and precede bile duct loss. If patients suffering from early CR are treated aggressively, the clinical and histopathological manifestations of CR can be completely reversed and bile duct loss can be prevented. We first tested whether the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR, and whether treatment reversed the expression. The percentage of p21+ BECs and the number of p21+ BECs per portal tract is significantly increased in early CR (26 +/- 17% and 3.6 +/- 3.1) compared to BECs in normal liver allograft biopsies or those with nonspecific changes (1 +/- 1% and 0.1 +/- 0.3; P: < 0.0001 and P: < 0.02), chronic hepatitis C (2 +/- 3% and 0.7 +/- 1; P: < 0.0001 and P: < 0.04) or obstructive cholangiopathy (7 +/- 7% and 0.7 +/- 0.6; P: < 0.006 and P: = 0.04). Successful treatment of early CR is associated with a decrease in the percentage of p21+ BECs and the number of p21+ BECs per portal tract. In vitro, nuclear p21(WAF1/Cip1) expression is increased in large and multinucleated BECs, and is induced by transforming growth factor (TGF)-beta. TGF-beta1 also increases expression of TGF-beta receptor II, causes phosphorylation of SMAD-2 and nuclear translocation of p21(WAF1/Cip1), which inhibits BEC growth. Because conversion from cyclosporine to tacrolimus is an effective treatment for early CR, we next tested whether these two immunosuppressive drugs directly influenced BEC growth in vitro. The results show that cyclosporine, but not tacrolimus, stimulates BEC TGF-beta1 production, which in turn, causes BEC mito-inhibition and up-regulation of nuclear p21(WAF1/Cip1). In conclusion, expression of the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR and decreases with successful recovery. Replicative senescence accounts for the characteristic BEC cytological alterations used for the diagnosis of early CR and lack of a proliferative response to injury. The ability of cyclosporine to inhibit the growth of damaged BECs likely accounts for the relative duct sparing properties of tacrolimus.

Induction of vascular adhesion protein-1 during liver allograft rejection and concomitant cytomegalovirus infection in rats

Vascular adhesion protein-1 (VAP-1) is an adhesion molecule controlling lymphocyte recirculation through high endothelial venules of the lymph nodes. It has also been shown to be induced and to mediate lymphocyte adhesion at sites of inflammation. We studied the expression of VAP-1 and two other inducible adhesion molecules ICAM-1 and VCAM-1 in our experimental model of rat liver allograft rejection and, in addition, the effect of concomitant rat cytomegalovirus (RCMV) infection on this expression. Expression of VAP-1, ICAM-1, and VCAM-1 was studied in rat liver allografts with or without RCMV infection, isografts, and normal rat liver. Immunoperoxidase technique and monoclonal antibodies including a novel anti-VAP-1 reagent were used. VAP-1 expression was induced by acute rejection in sinusoids, hepatocytes, and also in bile ducts, when compared to the isografts or normal liver, where only blood vessels were consistently positive. Sinusoidal and hepatocyte expression of VAP-1 was prolonged by the presence of RCMV. ICAM-1 and VCAM-1 expression was also induced by acute rejection. However, RCMV increased sinusoidal VCAM-1 expression compared to uninfected grafts. The present experimental study shows that VAP-1 is up-regulated in acute rejection of liver allografts, and that this up-regulation is prolonged by RCMV infection.