Effect of Genetic Variants of CCR2 and CCL2 on the Natural History of HIV-1 Infection

Paraoxonase-1: How a xenobiotic detoxifying enzyme has become an actor in the pathophysiology of infectious diseases and cancer

Both infectious and non-infectious diseases can share common molecular mechanisms, including oxidative stress and inflammation. External factors, such as bacterial or viral infections, excessive calorie intake, inadequate nutrients, or environmental factors, can cause metabolic disorders, resulting in an imbalance between free radical production and natural antioxidant systems. These factors may lead to the production of free radicals that can oxidize lipids, proteins, and nucleic acids, causing metabolic alterations that influence the pathogenesis of the disease. The relationship between oxidation and inflammation is crucial, as they both contribute to the development of cellular pathology. Paraoxonase 1 (PON1) is a vital enzyme in regulating these processes. PON1 is an enzyme that is bound to high-density lipoproteins and protects the organism against oxidative stress and toxic substances. It breaks down lipid peroxides in lipoproteins and cells, enhances the protection of high-density lipoproteins against different infectious agents, and is a critical component of the innate immune system. Impaired PON1 function can affect cellular homeostasis pathways and cause metabolically driven chronic inflammatory states. Therefore, understanding these relationships can help to improve treatments and identify new therapeutic targets. This review also examines the advantages and disadvantages of measuring serum PON1 levels in clinical settings, providing insight into the potential clinical use of this enzyme.

Impact of the MCP-1-2518A>G polymorphism on COVID-19 severity in the Iranian population: A case-control study

As a result of SARS-CoV-2 infection, the host's immune system is disrupted, and chemokines and cytokines are intensified to eliminate the virus, resulting in cytokine storm syndrome and acute respiratory distress syndrome (ARDS). Patients with COVID-19 have been observed to have elevated levels of MCP-1, a chemokine associated with the severity of the disease. In some diseases, polymorphisms in the regulatory region of the MCP-1 gene correspond to serum levels and disease severity. An attempt was made in this study to assess the relationship between MCP-1 G-2518A and serum MCP-1 levels in Iranian COVID-19 patients and the severity of the disease. In this study, patients were randomly sampled from outpatients on the first day of diagnosis and from inpatients on the first day of their hospitalization. Patients were classified into the outpatient (without symptoms or with mild symptoms) and inpatient (with moderate, severe, and critical symptoms) groups. The serum level of MCP-1 was measured by ELISA and the frequency of MCP-1 G-2518A gene polymorphism genotypes in COVID-19 patients was checked by the RFLP-PCR method. Participants with COVID-19 infection had a higher rate of underlying diseases, such as diabetes, high blood pressure, kidney disease, and cardiovascular disease than the control group (P-value < 0.001). Also, the frequency of these factors in inpatients was significantly higher compared to outpatients (P-value < 0.001). Additionally, the level of MCP-1 in serum was significantly different with an average of 11.90 in comparison to 2.98 in the control group (P-value, 0.05), which is attributed to elevated serum levels among patients in hospitals with an average of 11.72 in comparison to 2.98 in the control group. Compared with outpatients, inpatients had a higher frequency of the G allele of the MCP-1-2518 polymorphism (P-value < 0.05), while a notable difference was observed in the serum level of MCP-1 in COVID-19 patients with the MCP-1-2518 AA genotype in the whole group in comparison to the control group (P-value: 0.024). Totally, the results showed that a high frequency of the G allele is related to hospitalization and poor outcome in COVID-19 cases.

On the Role of Paraoxonase-1 and Chemokine Ligand 2 (C-C motif) in Metabolic Alterations Linked to Inflammation and Disease. A 2021 Update

Infectious and many non-infectious diseases share common molecular mechanisms. Among them, oxidative stress and the subsequent inflammatory reaction are of particular note. Metabolic disorders induced by external agents, be they bacterial or viral pathogens, excessive calorie intake, poor-quality nutrients, or environmental factors produce an imbalance between the production of free radicals and endogenous antioxidant systems; the consequence being the oxidation of lipids, proteins, and nucleic acids. Oxidation and inflammation are closely related, and whether oxidative stress and inflammation represent the causes or consequences of cellular pathology, both produce metabolic alterations that influence the pathogenesis of the disease. In this review, we highlight two key molecules in the regulation of these processes: Paraoxonase-1 (PON1) and chemokine (C-C motif) ligand 2 (CCL2). PON1 is an enzyme bound to high-density lipoproteins. It breaks down lipid peroxides in lipoproteins and cells, participates in the protection conferred by HDL against different infectious agents, and is considered part of the innate immune system. With PON1 deficiency, CCL2 production increases, inducing migration and infiltration of immune cells in target tissues and disturbing normal metabolic function. This disruption involves pathways controlling cellular homeostasis as well as metabolically-driven chronic inflammatory states. Hence, an understanding of these relationships would help improve treatments and, as well, identify new therapeutic targets.

Functional polymorphisms of the CCL2 and MBL genes cumulatively increase susceptibility to severe acute respiratory syndrome coronavirus infection

OBJECTIVES

To assess associations between the functional polymorphisms G-2518A at the chemokine (C-C motif) ligand 2 gene (CCL2) and mannose binding lectin (MBL) codon 54 variant (A/B) and susceptibility to SARS.

METHODS

We genotyped the CCL2 G-2518A and MBL codon 54 variant (A/B) in 4 case-control populations of Chinese descent, totally consisting of 932 patients with SARS and 982 control subjects.

RESULTS

Both the high-CCL2-producing GG genotype and the low-MBL-producing B allele were consistently associated with increased risks of SARS-CoV infection in all 4 case-control populations (joint P = 1.6 × 10(-4) and 4.9 × 10(-8), for CCL2 and MBL respectively), with no interaction between polymorphisms could be detected. Furthermore, all the 4 case-control studies demonstrated a cumulative effect on risk of SARS-CoV infection for the combination of polymorphisms (joint P = 1.3 × 10(-10)). However, tests using the area under the curve (AUC) indicated that at this stage, the polymorphisms were unlikely to be appropriate for risk prediction testing because of low AUC values (all <66%). Additionally, no association was observed between the polymorphisms and severity of SARS.

CONCLUSIONS

The CCL2 G-2518A and MBL codon 54 variant have a significantly cumulative effect on increased risk of SARS-CoV infection.

Frequency of CCR5Δ32 allele in healthy Bosniak population

Recent evidence has demonstrated the role of CCR5Δ32 in a variety of human diseases: from infectious and inflammatory diseases to cancer. Several studies have confirmed that genetic variants in chemokine receptor CCR5 gene are correlated with susceptibility and resistance to HIV infection. A 32-nucleotide deletion within the CCR5 reading frame is associated with decreased susceptibility to HIV acquisition and a slower progression to AIDS. Mean frequency of CCR5Δ32 allele in Europe is approximately 10%. The highest allele frequency is observed among Nordic populations (about 12%) and lower in the regions of Southeast Mediterranean (about 5%). Although the frequency of CCR5Δ32 was determined in numerous European populations, there is a lack of studies on this variant in the Bosnia and Hercegovina population. Therefore, the aim of our study was to assess the frequency of CCR5Δ32 allele in the cohort of Bosniaks and compare the results with European reports. CCR5Δ32 was detected by sequence-specific PCR in a sample of 100 healthy subjects from Bosnia and Herzegovina (DNA collected 2011-2013). Mean age of the cohort being 58.8 (± 10.7) years, with 82% of women. We identified 17 heterozygotes and one mutant homozygote in study group, with mean ∆32 allele frequency of 9.5%. CCR5∆32 allele frequency among Bosniaks is comparable to that found in Caucasian populations and follows the pattern of the north-southern gradient observed for Europe. Further studies on larger cohorts with adequate female-to-male ratio are necessary.

Evaluation of the pharmacogenetics of immune recovery in treated HIV-infected patients

INTRODUCTION

Combination antiretroviral therapy has markedly improved the survival rate and quality of life in patients infected with HIV due to the powerful suppressor effect that current antiretroviral drugs have on the viral load. Consequently, the immune system undergoes a substantial qualitative and quantitative improvement; and this leads to an increase in the absolute CD4(+) T-lymphocyte count and the restoration of lost T-cell responses against certain opportunistic pathogens. Unfortunately, not all patients who successfully suppress plasma viremia experience sufficient CD4(+) T-cell gain and these patients, in turn, are associated with worse outcomes. Pharmacogenetic studies have been used to investigate how a patient's genetic predisposition may affect their response to antiretroviral drugs.

AREAS COVERED

This article reviews the investigations that have been published on the association between host genetic determinants of CD4(+) T-cell gain in treated HIV-infected patients. Studies were identified through a PubMed database search. Longitudinal studies into pharmacogenetic association were specifically selected.

EXPERT OPINION

While the possibility of genetic predisposition to HIV therapeutics has potential, most studies provide inconsistent data. Inconsistency is often due to partial genetic evaluation, different categorization of poor immune recovery or due to small numbers of patients evaluated. Currently, studies still belong to the research laboratory stage and more studies are required to improve our understanding.

The rs1024611 regulatory region polymorphism is associated with CCL2 allelic expression imbalance

CC chemokine ligand 2 (CCL2) is the most potent monocyte chemoattractant and inter-individual differences in its expression level have been associated with genetic variants mapping to the cis-regulatory regions of the gene. An A to G polymorphism in the CCL2 enhancer region at position -2578 (rs1024611; A>G), was found in most studies to be associated with higher serum CCL2 levels and increased susceptibility to a variety of diseases such as HIV-1 associated neurological disorders, tuberculosis, and atherosclerosis. However, the precise mechanism by which rs1024611influences CCL2 expression is not known. To address this knowledge gap, we tested the hypothesis that rs1024611G polymorphism is associated with allelic expression imbalance (AEI) of CCL2. We used haplotype analysis and identified a transcribed SNP in the 3'UTR (rs13900; C>T) can serve as a proxy for the rs1024611 and demonstrated that the rs1024611G allele displayed a perfect linkage disequilibrium with rs13900T allele. Allele-specific transcript quantification in lipopolysaccharide treated PBMCs obtained from heterozygous donors showed that rs13900T allele were expressed at higher levels when compared to rs13900C allele in all the donors examined suggesting that CCL2 is subjected to AEI and that that the allele containing rs1024611G is preferentially transcribed. We also found that AEI of CCL2 is a stable trait and could be detected in newly synthesized RNA. In contrast to these in vivo findings, in vitro assays with haplotype-specific reporter constructs indicated that the haplotype bearing rs1024611G had a lower or similar transcriptional activity when compared to the haplotype containing rs1024611A. This discordance between the in vivo and in vitro expression studies suggests that the CCL2 regulatory region polymorphisms may be functioning in a complex and context-dependent manner. In summary, our studies provide strong functional evidence and a rational explanation for the phenotypic effects of the CCL2 rs1024611G allele.

The deleterious influence of tenofovir-based therapies on the progression of atherosclerosis in HIV-infected patients

We investigated the potential differential effects of antiretroviral therapies on unbalanced chemokine homeostasis and on the progression of atherosclerosis in HIV-infected patients. A two-year prospective study was performed in 67 consecutive HIV-infected patients initiating antiretroviral therapy with abacavir/lamivudine or tenofovir/emtricitabine. Circulating levels of inflammatory biomarkers, progression of subclinical atherosclerosis and expression levels of selected chemokines genes in circulating leukocytes were assessed. Control subjects showed significantly lower plasma concentrations of CRP, tPA, IL-6, and MCP-1 than HIV-infected patients at a baseline. After two years of followup, the observed decreases in plasma inflammatory biomarker levels were only significant for MCP-1, tPA, and IL-6. The decrease in plasma MCP-1 concentration was associated with the progression of atherosclerosis, and this effect was negligible only in patients receiving TDF-based therapy. Multivariate analysis confirmed that treatment with TDF was positively and significantly associated with a higher likelihood of subclinical atherosclerosis progression. However, the expression levels of selected genes in blood cells only showed associations with the viral load and total and HDL-cholesterol levels. Current antiretroviral treatments may partially attenuate the influence of HIV infection on certain inflammatory pathways, though patients receiving TDF therapy must be carefully monitored with respect to the presence and/or progression of atherosclerosis.

Genetic variations and heterosexual HIV-1 infection: analysis of clustered genes encoding CC-motif chemokine ligands

Several CC-motif chemokine ligands (CCLs) can block HIV-1-binding sites on CC-motif chemokine receptor 5 (CCR5) and inhibit viral entry. We studied single-nucleotide polymorphisms (SNPs) in genes encoding three CCR5 ligands (CCL3 (MIP-1a), CCL4 (MIP-1b)and CCL5 (RANTES)) along with an adjacent gene encoding a CCR2ligand (CCL2 (MCP-1)) to identify candidate markers for HIV-1 infection and pathogenesis. Analyses of 567 HIV-1 serodiscordant Zambian couples revealed that rs5029410C (in CCL3 intron 2) was associated with lower viral load (VL) in seroconverters, adjusted for gender and age (regression β=-0.57 log(10), P=4x10(-6)). Inaddition, rs34171309A in CCL3 exon 3 was associated with increased risk of HIV-1 acquisition in exposed seronegatives(hazard ratio=1.52, P=0.006 when adjusted for VL of the initially seropositive partner and genital ulcer/inflammation). SNPrs34171309 encodes a conservative Glu-to-Asp substitution. Fiven eighboring SNPs in tight linkage disequilibrium with rs34171309all showed similar associations with HIV-1 acquisition. How these multiple CCL3 SNPs may alter the occurrence or course of HIV-1 infection remains to be determined [corrected].

Effect of TNF-alpha genetic variants and CCR5 Delta 32 on the vulnerability to HIV-1 infection and disease progression in Caucasian Spaniards

BACKGROUND

Tumor necrosis factor alpha (TNF-alpha) is thought to be involved in the various immunogenetic events that influence HIV-1 infection.

METHODS

We aimed to determine whether carriage of the TNF-alpha-238G>A, -308G>A and -863 C>A gene promoter single nucleotide polymorphisms (SNP) and the CCR5 Delta 32 variant allele influence the risk of HIV-1 infection and disease progression in Caucasian Spaniards. The study group consisted of 423 individuals. Of these, 239 were uninfected (36 heavily exposed but uninfected [EU] and 203 healthy controls [HC]) and 184 were HIV-1-infected (109 typical progressors [TP] and 75 long-term nonprogressors [LTNP] of over 16 years' duration). TNF-alpha SNP and the CCR5 Delta 32 allele were assessed using PCR-RFLP and automatic sequencing analysis methods on white blood cell DNA. Genotype and allele frequencies were compared using the chi 2 test and the Fisher exact test. Haplotypes were compared by logistic regression analysis.

RESULTS

The distribution of TNF-alpha-238G>A, -308G>A and -863 C>A genetic variants was non-significantly different in HIV-1-infected patients compared with uninfected individuals: -238G>A, p = 0.7 and p = 0.3; -308G>A, p = 0.05 and p = 0.07; -863 C>A, p = 0.7 and p = 0.4, for genotype and allele comparisons, respectively. Haplotype analyses, however, indicated that carriers of the haplotype H3 were significantly more common among uninfected subjects (p = 0.04). Among the infected patients, the distribution of the three TNF-alpha genetic variants assessed was non-significantly different between TP and LTNP: -238G>A, p = 0.35 and p = 0.7; -308G>A, p = 0.7 and p = 0.6: -863 C>A, p = 0.2 and p = 0.2, for genotype and allele comparisons, respectively. Haplotype analyses also indicated non-significant associations. Subanalyses in the LTNP subset indicated that the TNF-alpha-238A variant allele was significantly overrepresented in patients who spontaneously controlled plasma viremia compared with those who had a detectable plasma viral load (genotype comparisons, p = 0.02; allele comparisons, p = 0.03). The CCR5 Delta 32 distribution was non-significantly different in HIV-1-infected patients with respect to the uninfected population (p = 0.15 and p = 0.2 for genotype and allele comparisons, respectively) and in LTNP vs TP (p = 0.4 and p = 0.5 for genotype and allele comparisons, respectively).

CONCLUSIONS

In our cohort of Caucasian Spaniards, TNF-alpha genetic variants could be involved in the vulnerability to HIV-1 infection. TNF-alpha genetic variants were unrelated to disease progression in infected subjects. The -238G>A SNP may modulate the control of viremia in LTNP. Carriage of the CCR5 Delta 32 variant allele had no effect on the risk of infection and disease progression.

Relationship between human immunodeficiency type 1 infection and expression of human APOBEC3G and APOBEC3F

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1)-infected individuals with a high viral set point progress to acquired immunodeficiency syndrome (AIDS) more rapidly than those with a low viral set point. It is not entirely clear which host and viral factors are responsible for the viral set point. Host factors that affect virus replication are likely to influence the viral set point. Human APOBEC proteins have been shown to restrict HIV-1 replication.

METHODS

This prospective study was conducted to determine the relationship between human APOBEC3G (hA3G) and APOBEC3F (hA3F) levels and the viral set point. Fourteen subjects were classified as having a high viral set point, and 16 were classified as having a low viral set point. We quantified the levels of hA3G and hA3F mRNA in HIV-1-infected, antiretroviral drug-naive individuals before and after infection.

RESULTS

We found a significant correlation between the hA3G mRNA level and the viral set point. The expression of hA3G and hA3F increased after infection, and the levels of hA3G and hA3F mRNA were significantly higher after infection in the low viral set point group, compared with the high viral set point group.

CONCLUSIONS

The results suggest that the level of hA3G expression affects the establishment of the viral set point and may therefore function as a host determinant in the pathogenesis of HIV-1 infection.