Clinical significance of the CCR5delta32 allele in hepatitis C

Like a Rolling Stone? A Review on Spontaneous Clearance of Hepatitis C Virus Infection

Elimination of hepatitis C virus (HCV) without the need for medical intervention, known as spontaneous clearance (SC), occurs at a significantly lower rate than in the case of hepatitis B virus infection and only in selected individuals, such as reportedly in Keith Richards, a guitarist of The Rolling Stones. The present paper provides an updated narrative review of the research devoted to the phenomenon in order to identify and discuss the demographic, lifestyle-related, clinical, viral genotype-related, and host genetic factors underpinning the SC occurrence. The body of evidence indicates that the likelihood of SC is decreased in older individuals, men, Black people, HIV-coinfected subjects, and intravenous drug and alcohol users. In turn, HBV coinfection and specific polymorphism of the genes encoding interferon lambda 3 (particularly at rs8099917) and interferon lambda 4 (particularly at rs12979860) and HLA genes increase the odds of SC. Numerous other host-specific genetic factors could be implicated in SC, but the evidence is limited only to certain ethnic groups and often does not account for confounding variables. SC of HCV infection is a complex process arising from a combination of various factors, though a genetic component may play a leading role in some cases. Understanding factors influencing the likelihood of this phenomenon justifies better surveillance of high-risk groups, decreasing health inequities in particular ethnic groups, and may guide the development of a prophylactic vaccine, which at present is not available, or novel therapeutic strategies. Further research is needed to elucidate the exact mechanisms underlying SC and to explore potential interventions that could enhance this natural antiviral response.

Beyond HIV infection: Neglected and varied impacts of CCR5 and CCR5Δ32 on viral diseases

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CCR5 regulates multiple cell types (e.g., T regulatory and Natural Killer cells) and immune responses.

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The effects of CCR5, CCR5Δ32 (variant associated with reduced CCR5 expression) and CCR5 antagonists vary between infections.

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CCR5 affects the pathogenesis of flaviviruses, especially in the brain.

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The genetic variant CCR5Δ32 increases the risk of symptomatic West Nile virus infection.

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The triad “CCR5, extracellular vesicles and infections” is an emerging topic.

The interactions between chemokine receptors and their ligands may affect susceptibility to infectious diseases as well as their clinical manifestations. These interactions mediate both the traffic of inflammatory cells and virus-associated immune responses. In the context of viral infections, the human C-C chemokine receptor type 5 (CCR5) receives great attention from the scientific community due to its role as an HIV-1 co-receptor. The genetic variant CCR5Δ32 (32 base-pair deletion in CCR5 gene) impairs CCR5 expression on the cell surface and is associated with protection against HIV infection in homozygous individuals. Also, the genetic variant CCR5Δ32 modifies the CCR5-mediated inflammatory responses in various conditions, such as inflammatory and infectious diseases. CCR5 antagonists mimic, at least in part, the natural effects of the CCR5Δ32 in humans, which explains the growing interest in the potential benefits of using CCR5 modulators for the treatment of different diseases. Nevertheless, beyond HIV infection, understanding the effects of the CCR5Δ32 variant in multiple viral infections is essential to shed light on the potential effects of the CCR5 modulators from a broader perspective. In this context, this review discusses the involvement of CCR5 and the effects of the CCR5Δ32 in human infections caused by the following pathogens: West Nile virus, Influenza virus, Human papillomavirus, Hepatitis B virus, Hepatitis C virus, Poliovirus, Dengue virus, Human cytomegalovirus, Crimean-Congo hemorrhagic fever virus, Enterovirus, Japanese encephalitis virus, and Hantavirus. Subsequently, this review addresses the impacts of CCR5 gene editing and CCR5 modulation on health and viral diseases. Also, this article connects recent findings regarding extracellular vesicles (e.g., exosomes), viruses, and CCR5. Neglected and emerging topics in “CCR5 research” are briefly described, with focus on Rocio virus, Zika virus, Epstein-Barr virus, and Rhinovirus. Finally, the potential influence of CCR5 on the immune responses to coronaviruses is discussed.

Assessing hepatitis C spontaneous clearance and understanding associated factors-A systematic review and meta-analysis

New advances in the treatment of hepatitis C provide high levels of sustained viral response but their expense limits availability in publicly funded health systems. The aim of this review was to estimate the proportion of patients who will spontaneously clear HCV, to identify factors that are associated with clearance and to support better targeting of directly acting antivirals. We searched Ovid EMBASE, Ovid MEDLINE and PubMed from 1 January 1994 to 30 June 2015 for studies reporting hepatitis C spontaneous clearance and/or demographic, clinical and behavioural factors associated with clearance. We undertook meta-analyses to estimate the odds of clearance for each predictor. Forty-three studies met the inclusion criteria, representing 20 110 individuals, and 6 of these studies included sufficient data to estimate spontaneous clearance. The proportion achieving clearance within 3, 6, 12 and 24 months following infection were, respectively, 19.8% (95% CI: 2.6%-47.5%), 27.9% (95% CI: 17.2%-41.8%), 36.1% (95% CI: 23.5%-50.9%) and 37.1% (95% CI: 23.7%-52.8%). Individuals who had not spontaneously cleared by 12 months were unlikely to do so. The likelihood of spontaneous clearance was lower in males and individuals with HIV co-infection, the absence of HBV co-infection, asymptomatic infection, black or nonindigenous race, nongenotype 1 infection, older age and alcohol or drug problems. This study suggests that patients continue to spontaneously clear HCV for at least 12 months following initial infection. However, injecting drug users are comparatively less likely to achieve clearance; thus, they should be considered a priority for early treatment given the continuing risks that these individuals pose for onwards transmission.

Chemokine Receptor 5 Has No Major Role in the Severity of Hepatitis C Virus-Related Liver Damage

Total or partial inactivation of the chemokine 5 (CC5) pathway, as caused by the CC5 receptor Δ32 deletion (CCR5Δ32), may result in a profound manipulation of immune surveillance with significant consequences on the course and response to therapy of diverse human infections, including HIV. It has been postulated that in chronic hepatitis C (CHC), such a deregulation of CC5 pathway may compromise T cell-dependent antiviral immune responses, which in turn may favor viral persistence. To test this hypothesis, we investigated a cohort of 100 patients with CHC in whom 12 heterozygous and 1 homozygous CCR5Δ32 mutations were detected compared to 8 and none in 98 healthy controls (13% vs. 8.2%, p = 0.36). As patients with and without CCR5Δ32 mutations were similar in terms of histological activity (p = 0.84) and fibrosis stage (p = 0.20) as well as CCR5 tissue expression, we reasonably exclude that this CCR5 mutation is significantly involved in the pathogenesis of CHC and may be a potential therapeutic target. However, deleted patients showed a significantly higher response to pegylated interferon-alfa (PEG-IFN), suggesting that a dormant immune system is more readily primed by immunostimulation.

CCR5Δ32 in HCV infection, HCV/HIV co-infection, and HCV-related diseases

Although a potential involvement of the CCR5Δ32 variant has already been suggested in relation to susceptibility to hepatitis C virus (HCV) infection, data from the literature is still quite controversial. Thus, our study evaluated the influence of the CCR5Δ32 allele variant in HCV infection, HCV/HIV co-infection, and HCV-related diseases in individuals from southern Brazil. A total of 1352 individuals were included in this study, divided into the following groups: Control (n = 274); HCV+ (n = 674); HIV+ (n = 300); HCV+/HIV+ (n = 104). Individuals from the HCV+ group were further stratified according to clinical/histological criteria, as HCV+/control (n = 124); HCV+/fibrosis (n = 268); HCV+/cirrhosis (n = 190); HCV+/hepatocarcinoma (n = 92). Considering all individuals included in this study, the following genotype frequencies were observed: wild-type homozygous (wt/wt), 88.76%; heterozygous (wt/Δ32), 10.72%; variant homozygous (Δ32/Δ32), 0.52%. Genotypic frequencies were very similar between the groups. Of note, the frequency of the Δ32 homozygous was quite similar comparing control uninfected against the HCV+ individuals (p > 0.999). The overall Δ32 allele frequency was estimated at 5.88%. Considering the number of Δ32 allele carriers and non-carriers, no statistically significant differences (p > 0.05) between the groups were observed, suggesting that the CCR5Δ32 variant does not influence the susceptibility to HCV infection, HCV/HIV co-infection, or HCV-related diseases in individuals from southern Brazil.

A Study on the Association between CCRΔ32 Mutation and HCV Infection in Iranian Patients

BACKGROUND

Mutations in the coding region of the Chemokine Receptor 5 (CCR5) genes reduce or eliminate CCR5 expression in immune cells and progression of HCV infection. This study aimed to investigate the role of this mutation in HCV infection in Iranian patients in comparison with healthy individuals.

METHODS

100 HCV infected patients and 100 healthy individuals were randomly selected. The CCR5Δ32 genotypes were determined using specific primers and PCR method.

RESULTS

The agarose gel electrophoresis showed a189-bp fragment from wild type for both alleles of CCR5 gene. The CCR5-Δ32 allele was not found in any HCV infected and healthy subjects.

CONCLUSION

The mutation in CCR5 gene was not detected in any of the two groups; therefore, the role of CCR5 gene expression in immune cells and progression of HCV infection needs to be studied in larger samples in our country.

Role of Some Predominant Host Immunomodulators' Single Nucleotide Polymorphisms in Severity of Hepatitis B Virus and Hepatitis C Virus Infection

Hepatitis B and C infections can be either acute or chronic. The chronic infection can culminate in liver cirrhosis and hepatocellular carcinoma. Influence of the host genetic makeup on conversion of acute to chronic infection, development of cirrhosis, and hepatocellular carcinoma is an interesting area of research. Variability in different immune system genes may account for such differences in the outcome of infection. This article discusses single nucleotide polymorphisms in different host immunomodulator genes that have been frequently reported to influence the outcome of infection and severity of disease. The genetic variability could be utilized for the prediction of disease outcome and treatment responses.