Variants in HAVCR1 gene region contribute to hepatitis C persistence in African Americans

Molecular Basis for the Differential Function of HAVCR1 Mucin Variants

Background/Objectives: The hepatitis A virus (HAV) cellular receptor 1 (HAVCR1) is a type I integral membrane glycoprotein discovered in monkeys and humans as a HAV receptor. HAVCR1 contains an N-terminal immunoglobulin-like variable domain (IgV) followed by a mucin-like domain (Muc), a transmembrane domain, and a cytoplasmic tail with a canonical tyrosine kinase phosphorylation site. The IgV binds phosphatidylserine on apoptotic cells, extracellular vesicles, and enveloped viruses. Insertions/deletions at position 156 (156ins/del) of the Muc were associated in humans with susceptibility to atopic, autoimmune, and infectious diseases. However, the molecular basis for the differential function of the HAVCR1 variants is not understood. Methods: We used mutagenesis, apoptotic cell binding, and signal transduction analyses to study the role of the 156ins/del in the function of HAVCR1. Results: We found that the HAVCR1 variant without insertions at position 156 (156delPMTTTV, or short-HAVCR1) bound more apoptotic cells than that containing a six amino acid insertion (156insPMTTTV, or long-HAVCR1). Furthermore, short-HAVCR1 induced stronger cell signaling and phagocytosis than long-HAVCR1. Conclusions: Our data indicated that the 156ins/del determine how the IgV is presented at the cell surface and modulate HAVCR1 binding, signaling, and phagocytosis, suggesting that variant-specific targeting could be used as therapeutic interventions to treat immune and infectious diseases.

Kidney Injury Molecule 1 (KIM-1): a Multifunctional Glycoprotein and Biological Marker (Review)

KIM-1 (kidney injury molecule 1) is a transmembrane glycoprotein also known as HAVcr-1 and TIM-1 belongs to the T-cell immunoglobulin and mucin domain family (TIM) of proteins. TIM glycoproteins are presented on the immune cells and participate in the regulation of immune reactions. KIM-1 differs from other members of its family in that it is expressed not only by immunocompetent cells but epithelial cells as well. Cellular and humoral effects mediated by KIM-1 are involved in a variety of physiological and pathophysiological processes.

Current understanding of the mechanisms determining the participation of KIM-1 in viral invasion, the immune response regulation, adaptive reactions of the kidney epithelium to acute ischemic or toxic injury, in progression of chronic renal diseases, and kidney cancer development have been presented in this review. Data of clinical researches demonstrating the association of KIM-1 with viral diseases and immune disorders have also been analyzed. Potential application of KIM-1 as urinary or serological marker in renal and cardiovascular diseases has been considered.

Symptomatic human immunodeficiency virus-infected patients have poorer outcomes following emergency general surgery: A study of the nationwide inpatient sample

BACKGROUND

The impact of human immunodeficiency virus (HIV) infection on outcomes following common emergency general surgery procedures has not been evaluated since the widespread introduction of highly active antiretroviral therapy.

METHODS

A retrospective cohort study was conducted using the Nationwide Inpatient Sample. Records of patients who underwent laparoscopic or open appendectomy, cholecystectomy, or colon resection after emergency admission from 2004 to 2011 were obtained. Outcomes analyzed included in-hospital mortality, length of stay, total charges, and selected postoperative complications. Patients were divided among three groups, HIV-negative controls, asymptomatic HIV-positive patients, and symptomatic HIV/acquired immune deficiency syndrome (AIDS) patients. Data were analyzed using χ and multivariable regression with propensity score matching among the three groups, with p value less than 0.05 significant.

RESULTS

There were 974,588 patients identified, of which 1,489 were HIV-positive and 1,633 were HIV/AIDS-positive. The HIV/AIDS patients were more likely to die during their hospital stay than HIV-negative patients (4.4% vs. 1.6%, adjusted odds ratio, 3.53; 95% confidence interval [CI], 2.67-4.07; p < 0.001). The HIV/AIDS patients had longer hospital stays (7 days vs. 3 days; adjusted difference, 3.66 days; 95% CI, 3.53-4.00; p < 0.001) and higher median total charges than HIV-negative patients (US $47,714 vs. US $28,405; adjusted difference, US $15,264; 95% CI, US $13,905-US $16,623; p < 0.001). The HIV/AIDS patients also had significantly increased odds of certain postoperative complications, including sepsis, septic shock, pneumonia, urinary tract infection, acute renal failure and need for transfusion (p < 0.05 for each). Differences persisted irrespective of case complexity and over the study period. Asymptomatic HIV-positive patients had outcomes similar to HIV-negative patients.

CONCLUSION

The HIV/AIDS patients have a greater risk of death, infectious, and noninfectious complications after emergency surgery regardless of operative complexity and despite advanced highly active antiretroviral therapy. Patients who have not developed advanced disease, however, have similar outcomes to HIV-negative patients.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III.

HAVCR1 Affects the MEK/ERK Pathway in Gastric Adenocarcinomas and Influences Tumor Progression and Patient Outcome

The hepatitis A virus cellular receptor 1 (HAVCR1) gene as a sensitive and specific biomarker has been reported in various diseases. Especially, HAVCR1 overexpression promotes the development and progression of several human cancers. Hence, we aimed to detect the effects of HAVCR1 on gastric adenocarcinoma (GAC). We first determined the expression of HAVCR1 in GAC tissues compared with normal gastric tissues based on the Cancer Genome Atlas (TCGA) database using bioinformatics analysis methods. Then, we assessed the biological function of HAVCR1 in GAC cells using quantitative real-time reverse transcription-PCR (qRT-PCR), western blot, cell counting kit-8- (CCK-) 8, colony formation assay, wound healing assay, and transwell assay. Our results showed that HAVCR1 expression was upregulated in GAC tissues and positively associated with poor survival. Loss-of-function analyses indicated that knockdown of HAVCR1 inhibited the proliferation, colony formation, migration, and invasion of GAC cells. Furthermore, reduction of HAVCR1 in GAC cells can decrease the expression of phosphorylated MEK/ERK. These findings suggested that HAVCR1 may represent a potential biomarker for GAC prognosis, as well as a novel therapeutic target for GAC treatment.

Genetic polymorphisms of rs9313422 G>C and rs41297579 G>A at the promoter of TIM-1 gene contribute to the risk of community-acquired pneumonia in children

OBJECTIVE

To investigate the association of genetic polymorphisms of rs9313422 G>C and rs41297579 G>A at the promoter of TIM-1 gene with the risk of community-acquired pneumonia (CAP) in children.

METHODS

A total of 112 children with CAP were included as the case group. Another 120 healthy children were enrolled as the control group. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was applied for the genotyping of rs9313422 G>C and rs41297579 G>A in the promoter region of TIM-1.

RESULTS

rs9313422 G>C was related to the risk of CAP in children under codominant model, dominant model, recessive model, and allele model. Besides, the A allele of rs41297579 G>A could increase the risk of CAP in children. Besides, the haplotype GA (rs9313422-rs41297579) and GG reduced the risk of children CAP, while haplotype CA had an elevated risk. rs9313422 G>C and rs41297579 G>A polymorphisms were both associated with the severity of CAP in children, and the rs9313422 G>C was also related to the ICU admission rate. In addition, patients carried with the mutant homozygotes of rs9313422 G>C and rs41297579 G>A showed higher levels of white blood cell (WBC), procalcitonin (PCT), and C-reactive protein (CRP) than the wild type and heterozygous genotypes carriers.

CONCLUSION

rs9313422 G>C and rs41297579 G>A polymorphisms in the promoter region of TIM-1 could increase the risk of CAP in children and showed a relation with inflammatory responses and severity.

Hepatitis C Virus Infection: Host⁻Virus Interaction and Mechanisms of Viral Persistence

Hepatitis C (HCV) is a major cause of liver disease, in which a third of individuals with chronic HCV infections may develop liver cirrhosis. In a chronic HCV infection, host immune factors along with the actions of HCV proteins that promote viral persistence and dysregulation of the immune system have an impact on immunopathogenesis of HCV-induced hepatitis. The genome of HCV encodes a single polyprotein, which is translated and processed into structural and nonstructural proteins. These HCV proteins are the target of the innate and adaptive immune system of the host. Retinoic acid-inducible gene-I (RIG-I)-like receptors and Toll-like receptors are the main pattern recognition receptors that recognize HCV pathogen-associated molecular patterns. This interaction results in a downstream cascade that generates antiviral cytokines including interferons. The cytolysis of HCV-infected hepatocytes is mediated by perforin and granzyme B secreted by cytotoxic T lymphocyte (CTL) and natural killer (NK) cells, whereas noncytolytic HCV clearance is mediated by interferon gamma (IFN-γ) secreted by CTL and NK cells. A host-HCV interaction determines whether the acute phase of an HCV infection will undergo complete resolution or progress to the development of viral persistence with a consequential progression to chronic HCV infection. Furthermore, these host-HCV interactions could pose a challenge to developing an HCV vaccine. This review will focus on the role of the innate and adaptive immunity in HCV infection, the failure of the immune response to clear an HCV infection, and the factors that promote viral persistence.

Association of HCV mutated proteins and host SNPs in the development of hepatocellular carcinoma

Hepatitis C virus plays a significant role in the development of hepatocellular carcinoma (HCC) globally. The pathogenic mechanisms of hepatocellular carcinoma with HCV infection are generally linked with inflammation, cytokines, fibrosis, cellular signaling pathways, and liver cell proliferation modulating pathways. HCV encoded proteins (Core, NS3, NS4, NS5A) interact with a broad range of hepatocytes derived factors to modulate an array of activities such as cell signaling, DNA repair, transcription and translational regulation, cell propagation, apoptosis, membrane topology. These four viral proteins are also implicated to show a strong conversion potential in tissue culture. Furthermore, Core and NS5A also trigger the accretion of the β-catenin pathway as a common target to contribute viral induced transformation. There is a strong association between HCV variants within Core, NS4, and NS5A and host single nucleotide polymorphisms (SNPs) with the HCC pathogenesis. Identification of such viral mutants and host SNPs is very critical to determine the risk of HCC and response to antiviral therapy. In this review, we highlight the association of key variants, mutated proteins, and host SNPs in development of HCV induced HCC. How such viral mutants may modulate the interaction with cellular host machinery is also discussed.

Race affects SVR12 in a large and ethnically diverse hepatitis C-infected patient population following treatment with direct-acting antivirals: Analysis of a single-center Department of Veterans Affairs cohort

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease. HCV cure has been linked to improved patient outcomes. In the era of direct-acting antivirals (DAAs), HCV cure has become the goal, as defined by sustained virological response 12 weeks (SVR12) after completion of therapy. Historically, African-Americans have had lower SVR12 rates compared to White people in the interferon era, which had been attributed to the high prevalence of non-CC interleukin 28B (IL28B) type. Less is known about the association between race/ethnicity and SVR12 in DAA-treated era. The aim of the study is to evaluate the predictors of SVR12 in a diverse, single-center Veterans Affairs population. We conducted a retrospective study of patients undergoing HCV therapy with DAAs from 2014 to 2016 at the VA Greater Los Angeles Healthcare System. We performed a multivariable logistic regression analysis to determine predictors of SVR12, adjusting for age, HCV genotype, DAA regimen and duration, human immunodeficiency virus (HIV) status, fibrosis, nonalcoholic fatty liver disease (NAFLD) fibrosis score, homelessness, mental health, and adherence. Our cohort included 1068 patients, out of which 401 (37.5%) were White people and 400 (37.5%) were African-American. Genotype 1 was the most common genotype (83.9%, N = 896). In the adjusted models, race/ethnicity and the presence of fibrosis were statistically significant predictors of non-SVR. African-Americans had 57% lower odds for reaching SVR12 (adj.OR = 0.43, 95% CI = 1.5-4.1) compared to White people. Advanced fibrosis (adj.OR = 0.40, 95% CI = 0.26-0.68) was also a significant predictor of non-SVR. In a single-center VA population on DAAs, African-Americans were less likely than White people to reach SVR12 when adjusting for covariates.

Determinants in the Ig Variable Domain of Human HAVCR1 (TIM-1) Are Required To Enhance Hepatitis C Virus Entry

Hepatitis C virus (HCV) is the leading cause of chronic hepatitis in humans. Several host molecules participate in HCV cell entry, but this process remains unclear. The complete unraveling of the HCV entry process is important to further understand viral pathogenesis and develop therapeutics. Human hepatitis A virus (HAV) cellular receptor 1 (HAVCR1), CD365, also known as TIM-1, functions as a phospholipid receptor involved in cell entry of several enveloped viruses. Here, we studied the role of HAVCR1 in HCV infection. HAVCR1 antibody inhibited entry in a dose-dependent manner. HAVCR1 soluble constructs neutralized HCV, which did not require the HAVCR1 mucinlike region and was abrogated by a mutation of N to A at position 94 (N94A) in the Ig variable (IgV) domain phospholipid-binding pocket, indicating a direct interaction of the HAVCR1 IgV domain with HCV virions. However, knockout of HAVCR1 in Huh7 cells reduced but did not prevent HCV growth. Interestingly, the mouse HAVCR1 ortholog, also a phospholipid receptor, did not enhance infection and a soluble form failed to neutralize HCV, although replacement of the mouse IgV domain with the human HAVCR1 IgV domain restored the enhancement of HCV infection. Mutations in the cytoplasmic tail revealed that direct HAVCR1 signaling is not required to enhance HCV infection. Our data show that the phospholipid-binding function and other determinant(s) in the IgV domain of human HAVCR1 enhance HCV infection. Although the exact mechanism is not known, it is possible that HAVCR1 facilitates entry by stabilizing or enhancing attachment, leading to direct interactions with specific receptors, such as CD81.IMPORTANCE Hepatitis C virus (HCV) enters cells through a multifaceted process. We identified the human hepatitis A virus cellular receptor 1 (HAVCR1), CD365, also known as TIM-1, as a facilitator of HCV entry. Antibody blocking and silencing or knockout of HAVCR1 in hepatoma cells reduced HCV entry. Our findings that the interaction of HAVCR1 with HCV early during infection enhances entry but is not required for infection support the hypothesis that HAVCR1 facilitates entry by stabilizing or enhancing virus binding to the cell surface membrane and allowing the correct virus-receptor positioning for interaction with the main HCV receptors. Furthermore, our data show that in addition to the phospholipid-binding function of HAVCR1, the enhancement of HCV infection involves other determinants in the IgV domain of HAVCR1. These findings expand the repertoire of molecules that HCV uses for cell entry, adding to the already complex mechanism of HCV infection and pathogenesis.

Association between interferon use and reduced metabolic and vascular complications among patients with hepatitis C

We examined whether interferon treatment is associated with reduced metabolic/vascular complications in hepatitis C virus patients. The study had historical prospective cohort design using Maryland Medicaid administrative data (2006-2009). The end point was the incidence rate of mild, severe and combined mild/severe events from the Diabetes Complications Severity Index (DCSI). Interferon-treated and -untreated hepatitis C virus patients were matched on baseline covariates. Using multivariate counting process Cox regressions, we modeled the association between interferon receipt of at least 24 weeks and DCSI events incidence rate. Treated whites had similar rate of mild DCSI events, significantly 64% (p < 0.01) lower rate of severe DCSI events, and overall 29% (p = 0.14) lower rate of mild/severe DCSI events, compared with untreated whites. Compared with untreated blacks, treated blacks had a similar rate of DSCI events. Future studies should confirm our findings and should include important clinical variables such as viral genotype, virologic count and achieving sustained virologic response.

Hepatitis C in African Americans

The care of hepatitis C virus (HCV) in African Americans represents an opportunity to address a major health disparity in medicine. In all facets of HCV infection, African Americans are inexplicably affected, including in the prevalence of the virus, which is higher among them compared with most of the racial and ethnic groups. Ironically, although fibrosis rates may be slow, hepatocellular carcinoma and mortality rates appear to be higher among African Americans. Sustained viral response (SVR) rates have historically significantly trailed behind Caucasians. The reasons for this gap in SVR are related to both viral and host factors. Moreover, low enrollment rates in clinical trials hamper the study of the efficacy of anti-viral therapy. Nevertheless, the gap in SVR between African Americans and Caucasians may be narrowing with the use of direct-acting agents. Gastroenterologists, hepatologists, primary care physicians, and other health-care providers need to address modifiable risk factors that affect the natural history, as well as treatment outcomes, for HCV among African Americans. Efforts need to be made to improve awareness among health-care providers to address the differences in screening and referral patterns for African Americans.