Mitochondrial haplogroup H is related to CD4+ T cell recovery in HIV infected patients starting combination antiretroviral therapy

Common mitochondrial haplogroups as modifiers of the onset-age for critical COVID-19

As a key regulator of innate immunity, mitochondrial function is essential to maintain antiviral activities. Common mitochondrial DNA variants (haplogroups) have been associated with different physiological capacities and the nrisk of developing several diseases. Haplogroup H was associated with increased survival among sepsis patients, and lower risk of progression toward AIDS in HIV infected and lower manifestation of severe manifestation of herpex virus disease. We studied 316 Spanish with critical COVID-19, and found that the 7028C (haplogroup H) was protective among patients with early-onset disease (≤65 vs > 65 years, p = 0.01), while the ancestral 16223T was a risk factor for early-onset critical COVID-19 (OR = 3.36, 95 %CI = 1.49-7.54). Our work suggested that common mitochondrial variants may serve as predictors of COVID-19 severity. Additional studies to confirm this effect from other populations are of special interest.

DBP rs7041 and DHCR7 rs3829251 are Linked to CD4+ Recovery in HIV Patients on Antiretroviral Therapy

Background: The lack of the recovery of CD4⁺ T-cells (CD4⁺ recovery) among immunodeficiency virus (HIV)-infected patients on antiretroviral therapy (ART) is not well known. We aimed to analyze the association between single nucleotide polymorphisms (SNPs) underlying vitamin D metabolism and the CD4⁺ recovery in naïve HIV-infected patients who started ART with low baseline CD4⁺.

Methods: We conducted a retrospective study in 411 naïve individuals with plasma HIV load >200 copies/mL and CD4⁺ <200 cells/mm³. During 24 months of follow-up, all patients had plasma HIV load <50 copies/mL. DNA genotyping was performed using the Sequenom MassARRAY platform. The outcome variable was the change in CD4⁺ during the study.

Results: CD4⁺ recovery was higher in patients carrying DBP rs7041 AA genotype (AA versus CC/AC) and DHCR7 rs3829251 AA genotype (AA versus GG/AG) (p-value < 0.05). DBP rs7041 AA genotype was linked to increase in CD4⁺ (adjusted arithmetic mean ratio (aAMR) = 1.22; q-value = 0.011), increase in CD4⁺ ≥P75th [adjusted odds ratio (aOR) = 2.31; q-value = 0.005], slope of CD4⁺ recovery (aAMR = 1.25; q-value = 0.008), slope of CD4⁺ recovery ≥ P75th (aOR = 2.55; q-value = 0.005) and achievement of CD4⁺ ≥500 cells/mm³ (aOR = 1.89; q-value = 0.023). Besides, DHCR7 rs3829251 AA genotype was related to increase in CD4⁺ (aAMR = 1.43; q-value = 0.031), increase in CD4⁺ ≥P75th (aOR = 3.92; q-value = 0.030), slope of CD4⁺ recovery (aAMR = 1.40; q-value = 0.036), slope of CD4⁺ recovery ≥ P75th (aOR = 3.42; q-value = 0.031) and achievement of CD4⁺ ≥500 cells/mm³ (aOR = 5.68; q-value = 0.015).

Conclusion: In summary, DHCR7 rs3829251 and DBP rs7041 polymorphisms were associated with CD4⁺ recovery in HIV-infected patients who started cART with low CD4⁺ T-cell counts.

The Role of Mitochondrial DNA Variation in Drug Response: A Systematic Review

Background: The triad of drug efficacy, toxicity and resistance underpins the risk-benefit balance of all therapeutics. The application of pharmacogenomics has the potential to improve the risk-benefit balance of a given therapeutic via the stratification of patient populations based on DNA variants. A growth in the understanding of the particulars of the mitochondrial genome, alongside the availability of techniques for its interrogation has resulted in a growing body of literature examining the impact of mitochondrial DNA (mtDNA) variation upon drug response. Objective: To critically evaluate and summarize the available literature, across a defined period, in a systematic fashion in order to map out the current landscape of the subject area and identify how the field may continue to advance. Methods: A systematic review of the literature published between January 2009 and December 2020 was conducted using the PubMed database with the following key inclusion criteria: reference to specific mtDNA polymorphisms or haplogroups, a core objective to examine associations between mtDNA variants and drug response, and research performed using human subjects or human in vitro models. Results: Review of the literature identified 24 articles reporting an investigation of the association between mtDNA variant(s) and drug efficacy, toxicity or resistance that met the key inclusion criteria. This included 10 articles examining mtDNA variations associated with antiretroviral therapy response, 4 articles examining mtDNA variants associated with anticancer agent response and 4 articles examining mtDNA variants associated with antimicrobial agent response. The remaining articles covered a wide breadth of medications and were therefore grouped together and referred to as "other." Conclusions: Investigation of the impact of mtDNA variation upon drug response has been sporadic to-date. Collective assessment of the associations identified in the articles was inconclusive due to heterogeneous methods and outcomes, limited racial/ethnic groups, lack of replication and inadequate statistical power. There remains a high degree of idiosyncrasy in drug response and this area has the potential to explain variation in drug response in a clinical setting, therefore further research is likely to be of clinical benefit.

Investigating the importance of individual mitochondrial genotype in susceptibility to drug-induced toxicity

The mitochondrion is an essential organelle responsible for generating cellular energy. Additionally, mitochondria are a source of inter-individual variation as they contain their own genome. Evidence has revealed that mitochondrial DNA (mtDNA) variation can confer differences in mitochondrial function and importantly, these differences may be a factor underlying the idiosyncrasies associated with unpredictable drug-induced toxicities. Thus far, preclinical and clinical data are limited but have revealed evidence in support of an association between mitochondrial haplogroup and susceptibility to specific adverse drug reactions. In particular, clinical studies have reported associations between mitochondrial haplogroup and antiretroviral therapy, chemotherapy and antibiotic-induced toxicity, although study limitations and conflicting findings mean that the importance of mtDNA variation to toxicity remains unclear. Several studies have used transmitochondrial cybrid cells as personalised models with which to study the impact of mitochondrial genetic variation. Cybrids allow the effects of mtDNA to be assessed against a stable nuclear background and thus the in vitro elucidation of the fundamental mechanistic basis of such differences. Overall, the current evidence supports the tenet that mitochondrial genetics represent an exciting area within the field of personalised medicine and drug toxicity. However, further research effort is required to confirm its importance. In particular, efforts should focus upon translational research to connect preclinical and clinical data that can inform whether mitochondrial genetics can be useful to identify at risk individuals or inform risk assessment during drug development.

Incomplete immune reconstitution in HIV/AIDS patients on antiretroviral therapy: Challenges of immunological non-responders

The morbidity and mortality of HIV type-1 (HIV-1)-related diseases were dramatically diminished by the grounds of the introduction of potent antiretroviral therapy, which induces persistent suppression of HIV-1 replication and gradual recovery of CD4⁺ T-cell counts. However, ∼10-40% of HIV-1-infected individuals fail to achieve normalization of CD4⁺ T-cell counts despite persistent virological suppression. These patients are referred to as "inadequate immunological responders," "immunodiscordant responders," or "immunological non-responders (INRs)" who show severe immunological dysfunction. Indeed, INRs are at an increased risk of clinical progression to AIDS and non-AIDS events and present higher rates of mortality than HIV-1-infected individuals with adequate immune reconstitution. To date, the underlying mechanism of incomplete immune reconstitution in HIV-1-infected patients has not been fully elucidated. In light of this limitation, it is of substantial practical significance to deeply understand the mechanism of immune reconstitution and design effective individualized treatment strategies. Therefore, in this review, we aim to highlight the mechanism and risk factors of incomplete immune reconstitution and strategies to intervene.

IL7RA rs6897932 Polymorphism is Associated with Better CD4+ T-Cell Recovery in HIV Infected Patients Starting Combination Antiretroviral Therapy

Interleukin-7 receptor subunit alpha (IL7RA) rs6897932 polymorphism IS related to CD4⁺ recovery after combination antiretroviral therapy (cART), but no studies so far have analyzed its potential impact in patients with very low CD4⁺ T-cells count. We aimed to analyze the association between IL7RA rs6897932 polymorphism and CD4⁺ T-cells count restoration in HIV-infected patients starting combination antiretroviral therapy (cART) with CD4⁺ T-cells count <200 cells/mm³. We performed a retrospective study in 411 patients followed for 24 months with a DNA sample available for genotyping. The change in CD4⁺ T-cells count during the follow-up was considered as the primary outcome. The rs6897932 polymorphism had a minimum allele frequency (MAF) >20% and was in Hardy–Weinberg equilibrium (p = 0.550). Of 411 patients, 256 carried the CC genotype, while 155 had the CT/TT genotype. The CT/TT genotype was associated with a higher slope of CD4⁺ T-cells recovery (arithmetic mean ratio; AMR = 1.16; p = 0.016), higher CD4⁺ T-cells increase (AMR = 1.19; p = 0.004), and higher CD4⁺ T-cells count at the end of follow-up (AMR = 1.13; p = 0.006). Besides, rs6897932 CT/TT was related to a higher odds of having a value of CD4⁺ T-cells at the end of follow-up ≥500 CD4⁺ cells/mm³ (OR = 2.44; p = 0.006). After multiple testing correction (Benjamini–Hochberg), only the increase of ≥ 400 CD4⁺ cells/mm³ lost statistical significance (p = 0.052). IL7RA rs6897932 CT/TT genotype was related to a better CD4⁺ T-cells recovery and it could be used to improve the management of HIV-infected patients starting cART with CD4⁺ T-cells count <200 cells/mm³.