Immunoglobulin G genetic variation can confound assessment of antibody levels via altered binding to detection reagents.

Objectives: Amino acid variations across more than 30 immunoglobulin (Ig) allotypes may introduce structural changes that influence recognition by anti-Ig detection reagents, consequently confounding interpretation of antibody responses, particularly in genetically diverse cohorts. Here, we assessed a panel of commercial monoclonal anti-IgG1 clones for capacity to universally recognise two dominant IgG1 haplotypes (G1m-1,3 and G1m1,17). Methods: Four commercial monoclonal anti-human IgG1 clones were assessed via ELISAs and multiplex bead-based assays for their ability to bind G1m-1,3 and G1m1,17 IgG1 variants. Detection antibodies were validated against monoclonal IgG1 allotype standards and tested for capacity to recognise antigen-specific plasma IgG1 from G1m-1,3 and G1m1,17 homozygous and heterozygous SARS-CoV-2 BNT162b2 vaccinated (n = 28) and COVID-19 convalescent (n = 44) individuals. An Fc-specific pan-IgG detection antibody corroborated differences between hinge- and Fc-specific anti-IgG1 responses. Results: Hinge-specific anti-IgG1 clone 4E3 preferentially bound G1m1,17 compared to G1m-1,3 IgG1. Consequently, SARS-CoV-2 Spike-specific IgG1 levels detected in G1m1,17/G1m1,17 BNT162b2 vaccinees appeared 9- to 17-fold higher than in G1m-1,3/G1m-1,3 vaccinees. Fc-specific IgG1 and pan-IgG detection antibodies equivalently bound G1m-1,3 and G1m1,17 IgG1 variants, and detected comparable Spike-specific IgG1 levels between haplotypes. IgG1 responses against other human coronaviruses and influenza were similarly poorly detected by 4E3 anti-IgG1 in G1m-1,3/G1m-1,3 subjects. Conclusion: Anti-IgG1 clone 4E3 confounds assessment of antibody responses in clinical cohorts owing to bias towards detection of G1m1,17 IgG1 variants. Validation of anti-Ig clones should include evaluation of binding to relevant antibody variants, particularly as the role of immunogenetics upon humoral immunity is increasingly explored in diverse populations.

Asymptomatic people with well-controlled HIV do not have abnormal left ventricular global longitudinal strain.

Background: Previous studies have reported impairment in systolic and diastolic function in people with HIV (PWHIV). Our aim was to determine if echocardiographically measured left ventricular (LV) global longitudinal strain (GLS) is abnormal in asymptomatic PWHIV. Methods: A cross-sectional study of PWHIV (n = 98, 89% male, median age 53 years) and HIV-negative people (n = 50, median age 53 years) without known cardiovascular disease were recruited from a single centre. All participants completed a health/lifestyle questionnaire, provided a fasting blood sample, and underwent a comprehensive echocardiogram for assessment of diastolic and systolic LV function, including measurement of GLS. Results: All PWHIV were receiving antiretroviral therapy (ART) for a median of 12 years (IQR: 6.9, 22.4), the majority with good virological control (87% suppressed) and without immunological compromise (median CD4 598 cells/µl, IQR: 388, 841). Compared with controls of similar age and gender, there was no difference in GLS [mean GLS -20.3% (SD 2.5%) vs. -21.0% (SD 2.5%), p = 0.14] or left ventricular ejection fractions [65.3% (SD 6.3) vs. 64.8% (SD 4.8), p = 0.62]. Following adjustment for covariates (gender, heart rate, systolic and diastolic blood pressure, and fasting glucose), the difference in GLS remained non-significant. There were no differences in LV diastolic function between the groups. Exposure to at least one mitochondrially toxic ART drug (didanosine, stavudine, zidovudine, or zalcitabine) was not associated with impairment of LV systolic function. Conclusion: No clinically significant impairment of myocardial systolic function, as measured by LV GLS, was detected in this predominantly Caucasian male population of PWHIV on long-term ART, with no history of cardiovascular disease.

Factors associated with the development of coronary artery disease in people with HIV.

BACKGROUND: People living with HIV (PLHIV) are at increased risk for coronary artery disease (CAD). This study aimed to describe the features associated with CAD in PLHIV. METHODS: A case ([n =160] PLHIV with CAD) control ([n =317] PLHIV matched by age and sex without CAD) study was performed at the Alfred Hospital, Melbourne, Australia (January 1996 and December 2018). Data collected included CAD risk factors, duration of HIV infection, nadir and at-event CD4+ T-cell counts, CD4:CD8 ratio, HIV viral load, and antiretroviral therapy exposure. RESULTS: Participants were predominantly male (n =465 [97.4%]), with a mean age of 53years. Traditional risk factors associated with CAD in univariate analysis included hypertension (OR 11.4 [95%CI 5.01, 26.33], P <0.001), current cigarette smoking (OR 2.5 [95% CI 1.22, 5.09], P =0.012), and lower high-density lipoprotein cholesterol (OR 0.14 [95%CI 0.05, 0.37], P <0.001). There was no association between duration of HIV infection, nadir or current CD4 cell count. However, current and ever exposure to abacavir (cases: 55 [34.4%]; controls: 79 [24.9%], P =0.023 and cases: 92 [57.5%]; controls: 154 [48.6%], P =0.048, respectively) was associated with CAD. In conditional logistic regression analysis, current abacavir use, current smoking, and hypertension remained significantly associated (aOR=1.87 [CI=1.14, 3.07], aOR=2.31 [1.32, 4.04], and aOR=10.30 [5.25, 20.20] respectively). CONCLUSION: Traditional cardiovascular risk factors and exposure to abacavir were associated with CAD in PLHIV. This study highlights that aggressive management of cardiovascular risk factors remains critical for reducing risk in PLHIV.

Robust SARS-CoV-2 T cell responses with common TCRαß motifs toward COVID-19 vaccines in patients with hematological malignancy impacting B cells.

Immunocompromised hematology patients are vulnerable to severe COVID-19 and respond poorly to vaccination. Relative deficits in immunity are, however, unclear, especially after 3 vaccine doses. We evaluated immune responses in hematology patients across three COVID-19 vaccination doses. Seropositivity was low after a first dose of BNT162b2 and ChAdOx1 (∼26%), increased to 59%-75% after a second dose, and increased to 85% after a third dose. While prototypical antibody-secreting cells (ASCs) and T follicular helper (Tfh) cell responses were elicited in healthy participants, hematology patients showed prolonged ASCs and skewed Tfh2/17 responses. Importantly, vaccine-induced expansions of spike-specific and peptide-HLA tetramer-specific CD4+/CD8+ T cells, together with their T cell receptor (TCR) repertoires, were robust in hematology patients, irrespective of B cell numbers, and comparable to healthy participants. Vaccinated patients with breakthrough infections developed higher antibody responses, while T cell responses were comparable to healthy groups. COVID-19 vaccination induces robust T cell immunity in hematology patients of varying diseases and treatments irrespective of B cell numbers and antibody response.

Effect of Rosuvastatin Therapy on Biomarkers of Inflammation and Immune Activation in People With Human Immunodeficiency Virus at Intermediate Cardiovascular Risk.

BACKGROUND: Statins may help prevent cardiovascular disease (CVD) in people with human immunodeficiency virus (PWH) with chronic inflammation owing to their pleotropic lipid-lowering and anti-inflammatory properties. METHODS: The impact of 48 weeks of rosuvastatin therapy on inflammation and immune activation in a double-blind, placebo-controlled trial in PWH at moderate cardiovascular disease risk was assessed. RESULTS: Rosuvastatin did not alter plasma levels of interleukin 6, soluble tumor necrosis factor receptor type 2, CXCL10, soluble CD14, or soluble vascular cellular adhesion molecule 1 (P ≥ .1 for all). Proportions of CD16+ monocyte subsets were increased in PWH receiving rosuvastatin. CONCLUSIONS: The potential benefits of statin use in PWH with normal lipid levels requires further clinical outcome research.

Impact of rosuvastatin on atherosclerosis in people with HIV at moderate cardiovascular risk: a randomised, controlled trial.

BACKGROUND: People living with HIV-1 (PLHIV) are at increased risk for cardiovascular disease. OBJECTIVE: This study aimed to determine if PLHIV would benefit from starting statins at a lower threshold than currently recommended in the general population. DESIGN: A double-blind multicentre, randomised, placebo-controlled trial was performed. METHODS: Participants (n = 88) with well controlled HIV, at moderate cardiovascular risk (Framingham score of 10-15%), and not recommended for statins were recruited from Australia and Switzerland. They were randomized 1 : 1 to rosuvastatin (n = 44) 20 mg daily, 10 mg if co-administered with ritonavir/cobicistat-boosted antiretroviral therapy, or placebo (n = 40) for 96 weeks. Assessments including fasting blood collection and carotid--intima media thickness (CIMT) were performed at baseline, and weeks 48 and 96. The primary outcome was the change from baseline to week 96 in CIMT (clinicaltrials.gov: NCT01813357). RESULTS: Participants were predominantly men [82 (97.6%); mean age 54 years (SD 6.0)]. At 96 weeks, there was no difference in the progression of CIMT between the rosuvastatin (mean 0.004 mm, SE 0.0036) and placebo (0.0062 mm, SE 0.0039) arms (P = 0.684), leading to no difference in CIMT levels between groups at week 96 [rosuvastatin arm, 0.7232 mm (SE 0.030); placebo arm 0.7785 mm (SE 0.032), P = 0.075].Adverse events were common (n = 146) and predominantly in the rosuvastatin arm [108 (73.9%)]. Participants on rosuvastatin were more likely to cease study medication because of an adverse event [7 (15.9%) vs. 2 (5.0%), P = 0.011]. CONCLUSION: In PLHIV, statins prescribed at a lower threshold than guidelines did not lead to improvements in CIMT but was associated with significant adverse events.

Monocytes from men living with HIV exhibit heightened atherogenic potential despite long-term viral suppression with antiretroviral therapy.

OBJECTIVE: People living with HIV have an increased risk of cardiovascular disease (CVD) despite effective antiretroviral therapy (ART). Monocytes play a key role in the early stages of atherosclerosis-driven CVD by forming lipid-laden foam cells within artery walls. HIV infection potentiates foam cell formation ex vivo, but the mechanisms contributing to this are not known. METHODS: We investigated the atherosclerosis-promoting potential of monocytes from 39 virologically suppressed men living with HIV (MLHIV) on ART and no evidence of CVD, and 25 HIV-uninfected controls of comparable age, sex, smoking status and CVD risk. RESULTS: Despite absence of clinical atherosclerosis in both MLHIV and uninfected cohorts (evidenced by a carotid intima-media thickness of 0.6 mm for both groups; P = 0.254), monocytes from MLHIV showed increased potential to form atherosclerosis-promoting foam cells compared with controls in an ex-vivo assay (36.6% vs. 27.6%, respectively, P = 0.003). Consistent with observations of persistent inflammation and immune/endothelial activation in ART-treated HIV infection, levels of soluble tumour necrosis factor receptor II, CXCL10 and soluble VCAM-1 were elevated in MLHIV (P ≤ 0.005 for all), but were not significantly associated with foam cell formation. Foam cell formation was associated with an impaired ability of monocytes to undergo reverse transmigration, and a reduced ability to efflux cholesterol ex vivo (P < 0.05 for both). Importantly, foam cell formation declined significantly with duration of viral suppression (P = 0.004). CONCLUSION: These findings highlight the persistence of HIV-related changes to the atherogenic potential of monocytes despite long-term viral suppression, and provide insights into mechanisms potentially driving increased CVD in ART-treated HIV infection.

Immune Biomarkers in the Prediction of Future Myocardial Infarctions in People With Human Immunodeficiency Virus.

In a retrospective case control analysis, following adjustments for high-sensitivity C-reactive protein (hsCRP), traditional cardiovascular risk factors, and the CD4/CD8 T-cell ratio, higher lipopolysaccharide-binding protein (LBP) was associated with future myocardial infarctions in hsCRP human immunodeficiency virus (HIV). LBP may be a marker of cardiovascular risk with utility in HIV.

Changes in plasma lipidome following initiation of antiretroviral therapy.

INTRODUCTION: HIV and antiretroviral therapy (ART) have been associated with increased cardiovascular disease and important changes in lipid metabolism. Advances in mass-spectrometry technology allow for the detailed assessment of individual lipid species which may illuminate the mechanisms underlying increased cardiovascular risk. We describe the change in plasma lipidome with initiation of antiretroviral therapy and compare these by regimen. METHODS: Plasma lipid profiling (by electrospray isonisation-tandem mass spectrometry) was performed on ARV-naive HIV positive participants randomised to one of three regimens; tenofovir/emtricitabine with efavirenz, ritonavir-boosted atazanavir (atazanavir/r) or zidovudine/abacavir. Participants (n = 115) who remained on their randomised regimen with complete samples available at baseline, week 12 and 48 were included. 306 lipid species from 22 lipid classes were analysed. RESULTS: Initiation of ART led to significant changes in lipidome which were partly dependent on the randomised regimen received. This led to significant differences in 72 lipid species and 7 classes (cholesterol ester, free cholesterol, phosphatidylcholine, GM3 ganglioside, trihexosylceramide, monohexosylceramide, and ceramides) by arm at week 48. Consistently higher lipid concentrations were seen with efavirenz compared with atazanavir/r or zidovudine/abacavir. Twelve of the lipid species and two lipid classes (cholesterol esters and ceramides) that were significantly increased in the efavirenz arm compared with the atazanavir/r or zidovudine/abacavir arms have previously been associated with future cardiovascular events in HIV positive patients. Change in HIV viral load was predictive of change in 3 lipid species. CONCLUSIONS: Initiation of ART lead to significant changes in the plasma lipidome that were greatest in those receiving efavirenz.

Predictors of chronic kidney disease and utility of risk prediction scores in HIV-positive individuals.

OBJECTIVE: The current study aimed to validate existing risk prediction scores and identify predictors of chronic kidney disease (CKD) in the setting of HIV. DESIGN AND METHODS: A retrospective cohort study of HIV-positive individuals (n = 748) with baseline estimated glomerular filtration rate (eGFR) more than 60 ml/min was conducted at the Alfred Hospital, Melbourne, Australia. Multivariable regression analysis was performed to determine factors associated with development of CKD, defined as two consecutive measurements of eGFR less than 60 ml/min. The performance of CKD risk scores proposed by the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) Study Group and Scherzer and colleagues were estimated by the area under the receiver operator curve (AUROC). RESULTS: CKD developed in 37 individuals (5.0%), at a median of 4.7 (interquartile range 2.2, 6.2) years. Older age [odds ratio (OR) 3.03, 95% confidence interval (CI): 1.20, 7.65, P = 0.02] and lower baseline eGFR (OR 10.39, 95% CI: 4.73, 22.83, P < 0.001) were associated with the development of CKD. Neither current, nor cumulative tenofovir disoproxil fumarate (TDF) use was associated with progression to CKD [current TDF hazard ratio (HR) 1.05, 95% CI: 0.54, 2.07, P = 0.88; cumulative TDF HR 1.03, 95% CI: 0.86, 1.24, P = 0.75]. The short D:A:D and Scherzer scores were well calibrated, with the short D:A:D score demonstrating superior discrimination (short D:A:D AUROC 0.85, Scherzer AUROC 0.78, P = 0.02). CONCLUSION: Older individuals and those with a lower baseline eGFR are at higher risk for CKD. Risk prediction tools may be useful in identifying those at greatest risk, who may benefit from aggressive management of risk factors.

Contribution of Common Infections to Cardiovascular risk in HIV Positive Individuals.

HIV-positive individuals are at increased risk for cardiovascular disease due to complex interactions between the increased incidence of traditional cardiovascular risk factors and HIV and antiretroviral-associated inflammation and dyslipidemia. Increasing evidence suggests that a number of important co-pathogens, including cytomegalovirus, hepatitis C virus, and periodontal disease, are likely to also be contributing. Mechanisms such as molecular mimicry and modification of lipids play a role; however, induction of systemic inflammation is the likely key pathogenic link by which this occurs. Treatments to reduce the presence of infection, such as antibiotics, antivirals, or dental hygiene, show potential as modifiers of cardiovascular risk in HIV-positive individuals. This review will discuss the evidence regarding the contribution of these key co-pathogens, Chlamydia pneumoniae, cytomegalovirus, and hepatitis C virus, to cardiovascular risk in HIV-positive individuals. It will also review the roles that inflammation, microbial translocation, and periodontal infection play in promoting cardiovascular disease. The potential cardiovascular benefits of treating these infections with antimicrobials (such as valganciclovir) or improvements in dental hygiene (in the setting of periodontal disease) will be explored. As the life expectancy of HIV-positive individuals increases and the HIV-positive population thus ages, reducing the impact of age-related comorbidities, and particularly cardiovascular disease, will be of increasing importance at both an individual and population level.

The impact of a multidisciplinary antimicrobial stewardship team on the timeliness of antimicrobial therapy in patients with positive blood cultures: a randomized controlled trial.

BACKGROUND: Antimicrobial stewardship teams play an important role in assisting with the optimization of antimicrobial use in acute care settings. We aimed to determine whether a rapid review by a multidisciplinary antimicrobial stewardship team would improve the timeliness of optimal antimicrobial therapy for patients with positive blood cultures. METHODS: This prospective randomized controlled trial was undertaken in two Australian hospitals. Patients received either standard care (a clinical microbiologist, registrar or laboratory scientist communicating the positive blood culture by phone to the treating doctor) or intervention (standard care plus rapid review by a multidisciplinary antimicrobial stewardship team). Outcomes included time to appropriate and/or active antimicrobial therapy and in-hospital mortality. The trial was registered on the Australian New Zealand Clinical Trials Registry (ACTRN12614000258651). RESULTS: A total of 160 patients were enrolled in this study: 81 in the standard care arm and 79 in the intervention arm. Patients in the intervention arm were commenced earlier on active (HR 8.02, 95% CI: 2.15-29.91) and appropriate antimicrobials (HR 1.95, 95% CI: 1.13-3.38), with a higher proportion of patients allocated to the intervention arm receiving active therapy at 48 h (96% versus 82%) and appropriate therapy at 72 h (70% versus 54%). The majority of patients where the blood culture was a contaminant were not started on antimicrobial therapy, and there were no significant differences in time to cessation of antimicrobial therapy. CONCLUSIONS: Antimicrobial stewardship team review of patients with pathogenic positive blood cultures improved the time to both active and appropriate antimicrobial therapy.

Effects of abacavir administration on structural and functional markers of platelet activation.

BACKGROUND: Current abacavir exposure has been reported to be associated with cardiovascular disease. Changes in platelet reactivity could plausibly explain the clinically observed pattern of association. OBJECTIVE: To determine if platelet reactivity changed following abacavir exposure and whether this effect was reversible on cessation of the drug. METHODS: In an open-label, interventional study abacavir, 600 mg daily, was added to a suppressive antiretroviral regimen in 20 adult HIV-positive men. Platelet function, estimated by the phosphorylated vasodilator-stimulated phosphoprotein (P-VASP) assay and through measurement of the expression and shedding of platelet-specific receptors, was assessed at baseline, following 15 days of abacavir and at completion of a 28-day washout period. RESULTS: The VASP-index decreased significantly from 79.1% [interquartile range (IQR) 47.8-87.6] to 32.6% (IQR -11.5-51.0) following 15 days of abacavir administration (P = 0.010), and returned to baseline levels following the washout period (day 43 =76.3%; IQR 40.7-92.3). There was no change in resting (prostaglandin E1 alone) P-VASP but a slight increase in P-VASP within stimulated platelets (prostaglandin E1 and adenosine diphosphate). Integrin ß3 levels decreased significantly [208.5 ng/ml (IQR 177.0-231.1) to 177.5 ng/ml (IQR 151.7-205) P < 0.001] and there was a nonsignificant trend towards decreased soluble glycoprotein VI levels [baseline; 72.5 ng/ml (95% CI 58.3-81.5) vs. day 15; 45.0 ng/ml (95% CI 33.0-98.2) P = 0.79]. CONCLUSION: Abacavir led to reversible changes in platelet function and structure. The clinical implications of these changes are uncertain; they may represent negative feedback mechanisms in response to an abacavir-associated prothrombotic state.

Plasma lipidomic profiling of treated HIV-positive individuals and the implications for cardiovascular risk prediction.

BACKGROUND: The increased risk of coronary artery disease in human immunodeficiency virus (HIV) positive patients is collectively contributed to by the human immunodeficiency virus and antiretroviral-associated dyslipidaemia. In this study, we investigate the characterisation of the plasma lipid profiles of treated HIV patients and the relationship of 316 plasma lipid species across multiple lipid classes with the risk of future cardiovascular events in HIV-positive patients. METHODS: In a retrospective case-control study, we analysed plasma lipid profiles of 113 subjects. Cases (n = 23) were HIV-positive individuals with a stored blood sample available 12 months prior to their diagnosis of coronary artery disease (CAD). They were age and sex matched to HIV-positive individuals without a diagnosis of CAD (n = 45) and with healthy HIV-negative volunteers (n = 45). RESULTS: Association of plasma lipid species and classes with HIV infection and cardiovascular risk in HIV were determined. In multiple logistic regression, we identified 83 lipids species and 7 lipid classes significantly associated with HIV infection and a further identified 74 lipid species and 8 lipid classes significantly associated with future cardiovascular events in HIV-positive subjects. Risk prediction models incorporating lipid species attained an area under the receiver operator characteristic curve (AUC) of 0.78 (0.775, 0.785)) and outperformed all other tested markers and risk scores in the identification of HIV-positive subjects with increased risk of cardiovascular events. CONCLUSIONS: Our results demonstrate that HIV-positive patients have significant differences in their plasma lipid profiles compared with healthy HIV-negative controls and that numerous lipid species were significantly associated with elevated cardiovascular risk. This suggests a potential novel application for plasma lipids in cardiovascular risk screening of HIV-positive patients.