Celestine N. Wanjalla

Purpose of review: Despite effective antiretroviral therapy (ART), persistent HIV reservoirs remain the primary obstacle to achieving an HIV cure. Understanding persistence requires defining not only reservoir size but also the identity and state of infected cells and their anatomical microenvironments – features that blood-based bulk measurements cannot resolve. We synthesize published findings from the Last Gift end-of-life cohort, in which longitudinal sampling and tissue donation via rapid autopsy have advanced our understanding of HIV persistence across anatomical compartments. We then highlight how integrated single-cell and spatial profiling can link proviral features to host-cell states and local tissue neighborhoods, helping to define the cellular and microenvironmental niches that sustain persistence. Recent findings: The Last Gift studies have mapped HIV DNA and envelope diversity across up to 33 anatomical compartments, inferred lymphoid and gastrointestinal tissues to be dominant sources of viral dispersal, shown that >85% of expanded proviral clones are shared across tissues, and recovered inducible, replication-competent virus from parietal-cortex microglia. Single-cell profiling has resolved heterogeneous microglial transcriptional and chromatin states containing rare HIV RNA or accessible proviral DNA and has identified a transcriptomic definition of cells expressing HIV RNA despite viral suppression on ART. Additionally, mass cytometry of viral sensors and restriction factors has defined tissue- and cell subset-specific antiviral programs, including restriction-factor profiles in lymph-node follicular helper T-cells predicted to favor HIV persistence. In parallel, imaging-based spatial transcriptomics with custom HIV probes, immunoPET/CT-guided tissue sampling, and duplex RNAscope/DNAscope have made direct localization of viral nucleic acids within annotated tissue neighborhoods technically feasible. No single assay, however, establishes proviral intactness, transcriptional activity, cellular identity, spatial position, and neighborhoods at once. Summary: Reservoir measurements should be reported by what each assay can establish rather than as interchangeable estimates of reservoir size. Cohorts such as the Last Gift, which yield matched blood and multiorgan tissue from the same donor with longitudinal clinical context, are well suited to applying direct proviral characterization, single-cell phenotyping and spatially resolved viral detection in parallel on the same specimens. This combination defines the resolution – intact provirus, in an identified cell, in a defined tissue niche – that cure trials should increasingly be expected to measure.

Chronic immune activation contributes to cardiometabolic disease and has most often been attributed to soluble mediators or changes in individual immune-cell subsets. A complementary dimension of immune organization is captured by direct physical interactions between immune cells, detected in blood or dissociated samples. While most dual-lineage flow-cytometric events should still be excluded as technical doublets, a validated subset represents true cell–cell conjugates (i.e. physically interacting immune cells rather than antibody-antigen complexes). The evidence base, however, is uneven as platelet–leucocyte aggregates are well-established biomarkers of platelet activation and thromboinflammation, while circulating non-platelet immune cell–cell complexes, particularly T cell-monocyte complexes, remain an emerging field supported by relatively few primary studies. Across acute infection and vaccination, these complexes appear regulated and may reflect coordinated immune activation. In chronic inflammatory states, including HIV and metabolic dysfunction, persistent complexes have been associated with inflammation and cardiometabolic risk, although mechanistic and causal data remain limited. Here, we review the current evidence for circulating immune cell complexes, distinguish established platelet-containing aggregates from the nascent literature on other immune-cell pairings, discuss candidate mechanisms that may support their formation and persistence, outline methodological requirements for their study, and consider their potential as biomarkers and therapeutic-response tools in cardiometabolic disease.

Background: Cytomegalovirus (CMV) is highly prevalent and associated with comorbidities in people with HIV-1 (PWH). Cytomegalovirus contributes to systemic inflammation, but comprehensive analyses of the plasma proteome in PWH with or without CMV are lacking. Methods: Plasma proteomes from 59 age- and CD4 count-matched PWH on suppressive antiretroviral therapy with (CMV+) or without (CMV−) CMV were characterized by inflammation- and cardiometabolic-focused proteomics proximity extension assays. Normalized protein expression values were analyzed using linear mixed-effects models, partial least squares-discriminant analysis, and gene set enrichment analysis. T-cell phenotypes were assessed by flow cytometry. Results: In covariate-unadjusted linear mixed-effects models, 118/350 (33.7%) inflammatory and 27/363 (7.4%) cardiometabolic proteins were differentially expressed (false discovery rate-adjusted P < .05). Proteins most significantly upregulated in CMV+ participants were associated with immune inhibition (eg, FcRL6, LY9, and HLA-DRA), cytotoxic differentiation (eg, KLRD1, CD70, and SLAMF7), and interferon-associated chemotaxis (eg, CXCL9 and CXCL10). Several of the most significantly downregulated proteins in CMV+ PWH were associated with apoptosis (eg, CASP2, TRIM21, and TRAF2). Surface FcRL6 expression was significantly elevated on CD57+CD28− CD8 T cells of CMV+ PWH. Conclusions: These data identify a CMV-associated plasma proteomic signature in treated HIV, characterized by immunoinhibitory/cytotoxic programs, supporting targeting CMV to reduce immune dysregulation and related comorbidities in PWH.

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The chemokine fractalkine (CX3CL1)-chemokine (CX3C motif) receptor 1 (CX3CR1) axis, comprising the chemokine fractalkine (CX3CL1) and its immune cell receptor CX3CR1, links immune activation to vascular pathology in people with human immunodeficiency virus (HIV; PWH). Chronic inflammation persists in PWH despite viral suppression with antiretroviral therapy and contributes to high rates of cardiometabolic comorbidities. This is partly due to dysregulated leukocyte trafficking and endothelial activation. This review synthesizes preclinical, genetic, and clinical evidence on the multifaceted roles of CX3CR1 across immune, vascular, and cardiometabolic processes. CX3CR1 is expressed on monocyte and cytotoxic T cell subsets implicated in endothelial injury, tissue trafficking, and plaque progression. On the other hand, CX3CL1 is expressed on activated endothelial and stromal cells, which promotes leukocyte adhesion and recruitment into inflamed tissues. In PWH, persistent immune activation and cytomegalovirus coinfections are associated with the expansion of differentiated CX3CR1-expressing T cell populations, supporting the relevance of this pathway to HIV-associated inflammatory comorbidities. At the genetic level, CX3CR1 polymorphisms, including V249I and T280M, alter receptor signaling and have been associated with HIV disease progression and cardiovascular disease risk, highlighting CX3CR1 as both a biomarker and potential mediator of immune-driven pathology. Across preclinical models, pharmacological targeting of CX3CR1 or CX3CL1 attenuates inflammation, fibrosis, and vascular injury in the selected disease contexts. However, the effects of CX3CR1 signaling are tissue- and cell type-specific, and blockade may carry potential risks in settings where CX3CR1 supports immune surveillance, mucosal repair, or macrophage homeostasis. This review evaluates the therapeutic promise and safety considerations of targeting the CX3CL1-CX3CR1 axis in HIV-associated cardiovascular and inflammatory comorbidities.

Male infertility is recognized as a complex condition associated with aging, yet its association with mitochondrial structural remodeling is poorly understood. Here, we integrated a multi-model approach to investigate how aging and MICOS complex dysfunction influence male reproductive health. Using the All of Us Research Program, we analyzed 121,064 male participants and performed age stratified PheWAS, LabWAS, and GWAS analyses comparing young (20 to 40 years) and older (≥55 years) cohorts. Male infertility was associated with distinct age dependent clinical phenotypes, laboratory alterations, and candidate loci linked to mitochondrial dysfunction. We examined semen samples using confocal microscopy and transmission electron microscopy upon inhibition of MICOS, which resulted in impaired sperm motility dynamics while increasing oxidative stress. We also used Drosophila melanogaster expressing mitochondrial green fluorescent protein in testes. Older flies displayed significant alterations in spermatid mitochondrial architecture, indicating disruption of mitochondrial network organization through aging. Complementary serial block face scanning electron microscopy and three-dimensional reconstructions of mouse testes revealed extensive age associated mitochondrial remodeling across residual, loose, and germ cell populations. Together, these findings identify mitochondrial MICOS complex integrity as a central regulator of age-associated male infertility across species, highlighting it as potential therapeutic target for age-related reproductive decline.

Long COVID Postural Orthostatic Tachycardia Syndrome (LCPOTS) is characterized by persistent orthostatic tachycardia and systemic symptoms following SARS-CoV-2 infection. Many features of LCPOTS suggest ongoing immune activation, but the mechanisms driving this response remain unclear. In this study, we show that patients with LCPOTS, compared with individuals who recovered from SARS-CoV-2 without POTS, exhibit increased monocyte mitochondrial content and superoxide production, along with downregulation of NRF2-dependent antioxidant enzymes. This is accompanied by a marked increase in the formation of isolevuglandins (IsoLGs) in monocytes, which modify self-proteins and act as neoantigens capable of activating T cells. Consistent with this, LCPOTS patients exhibit a 3-fold increase in circulating T cell-monocyte doublets with immunological synapse formation. T cells in these complexes display a proinflammatory effector-memory and TEMRA phenotype, producing IFN-γ and IL-17A, which correlated with symptom severity. Circulating cytokines, including IL-17A, IFN-γ, and TNF-α, are elevated in patients with LCPOTS by 1.5 to 3-fold. This immune response likely drives systemic inflammation and impaired cardiovagal regulation, hallmarks of LCPOTS. Our findings suggest that monocyte oxidative stress and IsoLG neoantigen formation sustain T cell activation, linking immune dysregulation to cardiovagal dysfunction. Targeting these pathways may offer novel therapeutic opportunities. Graphical

Mitochondrial dysfunction drives hypertensive heart failure and reflects impaired oxidative phosphorylation and altered organelle structure. The mechanisms linking hypertensive signaling to mitochondrial translation and architecture remain unclear. TACO1 is a mitochondrial translational activator required for cytochrome c oxidase subunit I synthesis and may regulate respiratory chain assembly. We tested whether angiotensin II type 1 receptor activation disrupts TACO1-dependent translation and drives inner membrane remodeling. Using mRen also known as (mRen2)27 hypertensive rat hearts, we assessed mitochondrial function, ultrastructure, and metabolism. AT1R activation reduced TACO1-dependent COX I translation and produced a selective deficiency in complex IV activity. This impaired oxidative phosphorylation and increased the production of reactive oxygen species. Mitochondria exhibited reduced volume, increased fragmentation, and disrupted cristae organization with lower integrity scores. Hypertensive hearts also showed reduced expression of OPA1 and MICOS components. Metabolomic profiling separated control and heart failure groups and revealed enrichment of amino acid, nucleotide, and mitochondrial energy pathways. Lipidomic analysis identified coordinated changes across lipid classes consistent with altered membrane composition. Pharmacological AT1R inhibition restored COX I translation, rescued complex IV activity, and improved cristae structure. These findings establish a mechanistic link between hypertensive signaling, mitochondrial translation, cristae organization, and metabolic remodeling in heart failure.

Objective: Dyslipidemia is common in people with HIV (PWH) and linked to cardiometabolic disease risk. Subcutaneous adipose tissue (SAT) regulates lipid storage and release, but how SAT cellular composition might influence circulating lipids in PWH on contemporary antiretroviral therapy (ART) is not well defined. Design: Cross-sectional, observational cohort of PWH on long-term contemporary ART with virologic suppression. Methods: We performed untargeted fasting plasma lipidomic profiling on 127 individuals with a range of metabolic fitness (non-diabetes, prediabetes, diabetes). Adjusted logistic and linear regression models identified lipid species associated with diabetes status and HOMA2-IR, respectively. Linear regression assessed the relationship between abdominal SAT cell composition from single-cell RNA sequencing with circulating lipid classes (n = 59). Results: The median age was 48 years, body mass index 31.5 kg/m ² , and 48% self-identified as non-White, with 23% women. Diabetes as a dichotomous outcome had few differences in lipid species. In contrast, HOMA2-IR was associated with higher levels of several species of tri- and diacylglycerols and inversely associated with phosphatidylcholine, phosphatidylethanolamine species, and many of their derivatives among those without diabetes. Adipose tissue microvasculature remodeling, characterized by a reduction in capillary endothelium and decreased expression of key lipid trafficking receptors ( LPL, GPIHBP1 ), was associated with the insulin-resistant lipidomic signature. Conclusions: Adipose tissue microvasculature remodeling in PWH on contemporary ART was associated with changes in several plasma lipid species, which are also linked to insulin resistance. Interventions targeting adipose tissue endothelial dysfunction may improve metabolic health in PWH on long-term ART.