Increased incidence of cytomegalovirus coinfection in HCV-infected patients with late liver fibrosis is associated with dysregulation of JAK-STAT pathway

The battle between host antiviral innate immunity and immune evasion by cytomegalovirus

Cytomegalovirus (CMV) has successfully established a long-lasting latent infection in humans due to its ability to counteract the host antiviral innate immune response. During coevolution with the host, the virus has evolved various evasion techniques to evade the host's innate immune surveillance. At present, there is still no vaccine available for the prevention and treatment of CMV infection, and the interaction between CMV infection and host antiviral innate immunity is still not well understood. However, ongoing studies will offer new insights into how to treat and prevent CMV infection and its related diseases. Here, we update recent studies on how CMV evades antiviral innate immunity, with a focus on how CMV proteins target and disrupt critical adaptors of antiviral innate immune signaling pathways. This review also discusses some classic intrinsic cellular defences that are crucial to the fight against viral invasion. A comprehensive review of the evasion mechanisms of antiviral innate immunity by CMV will help investigators identify new therapeutic targets and develop vaccines against CMV infection.

The Role of JAK/STAT Pathway in Fibrotic Diseases: Molecular and Cellular Mechanisms

There are four members of the JAK family and seven of the STAT family in mammals. The JAK/STAT molecular pathway could be activated by broad hormones, cytokines, growth factors, and more. The JAK/STAT signaling pathway extensively mediates various biological processes such as cell proliferation, differentiation, migration, apoptosis, and immune regulation. JAK/STAT activation is closely related to growth and development, homeostasis, various solid tumors, inflammatory illness, and autoimmune diseases. Recently, with the deepening understanding of the JAK/STAT pathway, the relationship between JAK/STAT and the pathophysiology of fibrotic diseases was noticed, including the liver, renal, heart, bone marrow, and lung. JAK inhibitor has been approved for myelofibrosis, and subsequently, JAK/STAT may serve as a promising target for fibrosis in other organs. Therefore, this article reviews the roles and mechanisms of the JAK/STAT signaling pathway in fibrotic diseases.

CMV specific T cell immune response in hepatitis C negative kidney transplant recipients receiving transplant from hepatitis C viremic donors and hepatitis C aviremic donors

Kidney transplants (KT) from hepatitis C (HCV) viremic donors to HCV negative recipients has shown promising renal outcomes, however, high incidence of cytomegalovirus (CMV) viremia were reported. We performed a prospective cohort study of 52 HCV negative KT recipients from Methodist University Hospital including 41 receiving transplants from HCV aviremic donors and 11 from HCV viremic donors. CMV specific CD4+ and CD8 + T cell immunity was measured by intracellular flow cytometry assay. Primary outcome was the development of positive CMV specific CD4+ and CD8 + T cell immune response in the entire cohort and each subgroup. The association between donor HCV status and CMV specific CD4+ and CD8 + T cell immune response was analyzed by Cox proportional hazard models. Mean recipient age was 48 ± 13 years, with 73% male and 82% African American. Positive CMV specific CD4+ and CD8 + T cell immune response was found in 53% and 47% of the cohort at 1 month, 65% and 70% at 2 months, 80% and 75% at 4 months, 89% and 87% at 6 months, and 94% and 94% at 9 months post-transplant, respectively. There was no significant difference in the incidence of positive CMV specific T cell immune response between recipients of transplants from HCV aviremic donors compared to HCV viremic donors in unadjusted (for CD8+: HR = 1.169, 95%CI: 0.521-2.623; for CD4+: HR = 1.208, 95%CI: 0.543-2.689) and adjusted (for CD8+: HR = 1.072, 95%CI: 0.458-2.507; for CD4+: HR = 1.210, 95%CI: 0.526-2.784) Cox regression analyses. HCV viremia in donors was not associated with impaired development of CMV specific T cell immunity in this cohort.

The Role of Interferon Regulatory Factors in Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease with many metabolic comorbidities, such as obesity, diabetes, and cardiovascular diseases. Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, accompanies the progression of hepatic steatosis, inflammation, cell death, and varying degree of liver fibrosis. Interferons (IFNs) have been shown to play important roles in the pathogenesis of NAFLD and NASH. Their regulating transcriptional factors such as interferon regulatory factors (IRFs) can regulate IFN expression, as well as genes involved in macrophage polarization, which are implicated in the pathogenesis of NAFLD and advanced liver disease. In this review, the roles of IRF-involved signaling pathways in hepatic inflammation, insulin resistance, and immune cell activation are reviewed. IRFs such as IRF1 and IRF4 are also involved in the polarization of macrophages that contribute to critical roles in NAFLD or NASH pathogenesis. In addition, IRFs have been shown to be regulated by treatments including microRNAs, PPAR modulators, anti-inflammatory agents, and TLR agonists or antagonists. Modulating IRF-mediated factors through these treatments in chronic liver disease can ameliorate the progression of NAFLD to NASH. Furthermore, adenoviruses and CRISPR activation plasmids can also be applied to regulate IRF-mediated effects in chronic liver disease. Pre-clinical and clinical trials for evaluating IRF regulators in NAFLD treatment are essential in the future direction.

IL28B, TLR7 SNPs, and cytomegalovirus infection are risk factors for advanced liver disease in chronic hepatitis C patients

BACKGROUND

Chronic hepatitis C (CHC) is a leading cause of cirrhosis and hepatocellular carcinoma (HCC). This study aimed to study the association of IL28B, toll-like receptor (TLR) 7, cytomegalovirus and advanced liver disease.

METHODS

Four groups were included; control (n = 125, 25.9%), CHC (n = 114, 23.6%), liver cirrhosis (n = 120, 24.8%), and HCC (n = 124, 25.7%).

RESULTS

In CHC group, patients were mainly F1 (60%) followed by F2. IL28B genotype CC percentage was higher in control group than the CHC and cirrhosis groups. CT and TT genotypes were higher in the CHC and cirrhosis groups than control group. The C allele was higher in the control group than the CHC, cirrhosis and HCC groups and the opposite with the T allele. Control and CHC had same TLR7 alleles. Cirrhosis patients and HCC had lower TLR 7 A allele and higher G allele than the control group. Both cirrhosis and HCC groups had statistically significant higher percentage of the AG and GG genotypes than the control group. Patients with HCC had higher cytomegalovirus infection percentage than cirrhosis and CHC group (38.7% vs 20% vs 16.7%), respectively.

CONCLUSION

IL28B, TLR7 SNPs and cytomegalovirus infection are risk factors for advanced liver disease in hepatitis C patients.

Cytomegalovirus Infection Downregulates Vitamin D Receptor in Patients Undergoing Hematopoietic Stem Cell Transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative option for patients with hematologic diseases but is associated with high mortality and morbidity. Cytomegalovirus (CMV) infection is common in HSCT patients and modulates vitamin D metabolism in vitro. We aimed at validating CMV-associated vitamin D metabolism in vivo in HSCT.

METHODS

Patients treated for significant CMV viremia after HSCT were evaluated for CMV load before, during, and after antiviral treatment. RNA was isolated from whole-blood samples to test for regulation of key components of the vitamin D receptor (VDR) pathway during different phases of CMV viremia.

RESULTS

CMV viremia developed a mean time of 102 (±34) d post-HSCT. Maximum levels of CMV-DNA reached a mean of 5668 (±7257) copies/mL. VDR expression was downregulated to a mean of 64.3% (±42.5%) relative to the VDR expression pre-CMV viremia (P = 0.035) and lagged in recovery following antiviral treatment. Toll-like receptor (TLR) 2 mRNA was upregulated to 225.4% during CMV viremia relative to the expression pre-CMV viremia (P = 0.012) but not TLR6/7/8 and the TLR-adaptor protein MyD88. Levels of 25-OH vitamin D were reduced in all viremic patients (48.0 ± 4.8 versus 25.1 ± 3.7 ng/mL) and were even lower after periods of CMV viremia compared with the control group (48.3 ± 3.5 versus 17.8 ± 1.8 ng/mL; P = 0.008).

CONCLUSIONS

CMV viremia is associated with significant dysregulation of vitamin D metabolism in HSCT patients.

Latent Cytomegalovirus Reactivation in Patients With Liver Failure: A 10-Year Retrospective Case-Control Study, 2011-2020

Background

The aim of this study was to explore potential risk factors for cytomegalovirus (CMV) reactivation and their impact on liver failure patient outcomes.

Methods

A 10-year retrospective case-control study was conducted in adult participants, who were diagnosed with liver failure and had undergone CMV DNA tests. CMV reactivation cases were matched with controls at a 2:1 ratio based on age, sex, and year of admission. Univariate and multivariate analyses were used to explore risk factors for CMV reactivation.

Results

Between January 2011 and April 2020, 198 adult patients with liver failure and available CMV DNA test results were enrolled into the study. Among them, 33 patients had detectable CMV DNA in their plasma (16.7%). Clinical manifestations and liver function were comparable between the CMV reactivation and non-reactivation groups. However, CMV reactivation may triple mortality in patients with liver failure. We found that nearly 50% of patients in the CMV-positive group received glucocorticoids, compared to 13.6% in the CMV-negative group (P=0.000). The median total glucocorticoid dose included 836.5 mg of methylprednisolone (IQR 308.7-1259.0 mg) in the CMV-positive group, which was significantly higher than that in the CMV-negative group. A multivariate analysis revealed that glucocorticoid use significantly increased the risk of CMV reactivation (adjusted OR, 4.84; 95% CI, 1.61-14.49; P=0.005). Patients with CMV reactivation tended to be associated with higher white cell counts (adjusted OR, 1.21; 95% CI, 1.08-1.36; P=0.002).

Conclusions

High intravenous glucocorticoid doses may be the most important risk factor for CMV reactivation in liver failure.

Reactivation of human cytomegalovirus inhibits expression of liver fibrosis related cytokines in patients chronically infected with hepatitis C virus genotype 4a

BACKGROUND

The impact of human cytomegalovirus (HCMV) reactivation on the expression pattern of matrix metalloproteinases, their inhibitors and related cytokines during HCV infection poorly understood.

METHODS

Reactivation of CMV in 95 subjects (75 chronically infected HCV patients and 20 healthy subjects) was examined. All studied subjects had detectable IgG antibodies for CMV, but only 35/75 of HCV patients (46.7%) had detectable CMV DNA. The expressions of 11 fibrosis related genes by quantitative real-time PCR were analyzed in subjects' PBMCs. The serum levels of TGFβ2 and PDGFα have been measured by ELISA.

RESULTS

Chronically infected HCV patients with reactivated CMV had less expression of TGF-β1, TGF-β2, PDGFα and STAT1 transcripts than HCV patients with latent CMV (p = 0.037, 0.006, 0.001 and 0.009; respectively) and normal controls (TGF-β2, p = 0.008). Moreover the expression of (TGFβ2 and PDGFα) genes decreased significantly in CMV-reactivated patients during the early stage of fibrosis relative to the comparable stage of HCV infection (p = 0.004 and 0.008; respectively). Besides, the mRNA abundance of STAT1 gene in CMV-reactivated patients decreased dramatically as compared to HCV infections during the late stage of fibrosis (p = 0.014). The TGFβ2 protein level has been declined dramatically in CMV-reactivated patients compared to HCV infected patients and control group (p = 0.001 and 0.033; respectively). Our results suggest that CMV reactivation disrupts the expression of several cytokines as compared to solitary infection with HCV. Noticeably, the expressions of matrix metalloproteinases genes and their inhibitors have not been significantly influenced by reactivation of CMV.

CONCLUSION

The current data reveal that reactivation of CMV partially blocks the upregulation of 2 important pro-inflammatory cytokines i.e. TGFβ 2 and PDGFα at early stages of fibrosis, moreover this CMV mediated blockage of the STAT1 shows statistical significance at late stage of fibrosis.

The antioxidant and DNA-repair enzyme apurinic/apyrimidinic endonuclease 1 limits the development of tubulointerstitial fibrosis partly by modulating the immune system

Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional protein that controls the cellular response to oxidative stress and possesses DNA-repair functions. It has important roles in the progression and outcomes of various diseases; however, its function and therapeutic prospects with respect to kidney injury are unknown. To study this, we activated APE1 during kidney injury by constructing an expression vector (pCAG-APE1), using an EGFP expression plasmid (pCAG-EGFP) as a control. We performed unilateral ureteral obstruction (UUO) as a model of tubulointerstitial fibrosis on ICR mice before each vector was administrated via retrograde renal vein injection. In this model, pCAG-APE1 injection did not produce any adverse effects and significantly reduced histological end points including fibrosis, inflammation, tubular injury, and oxidative stress, as compared to those parameters after pCAG-EGFP injection. qPCR analysis showed significantly lower expression of Casp3 and inflammation-related genes in pCAG-APE1-injected animals compared to those in pCAG-EGFP-injected UUO kidneys. RNA-Seq analyses showed that the major transcriptional changes in pCAG-APE1-injected UUO kidneys were related to immune system processes, metabolic processes, catalytic activity, and apoptosis, leading to normal kidney repair. Therefore, APE1 suppressed renal fibrosis, not only via antioxidant and DNA-repair functions, but also partly by modulating the immune system through multiple pathways including Il6, Tnf, and chemokine families. Thus, therapeutic APE1 modulation might be beneficial for the treatment of renal diseases.