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OBJECTIVE: Chronic inflammation contributes to the high burden of cardiovascular disease (CVD) in persons with HIV (PWH). HIV has broad effects on innate and adaptive immune cells, including innate lymphoid cells (ILCs) and CD4(+) T-helper cells. At present, the relationship between CVD and plasma cytokines reflecting ILC/T-helper responses in PWH is not well defined. We investigated relationships between plasma cytokines and subclinical atherosclerosis. DESIGN: Cross-sectional study. METHODS: We recruited 70 PWH on a single antiretroviral regimen (efavirenz, tenofovir, and emtricitabine) with at least 12 months of suppressed viremia and 30 HIV-negative controls. We quantified plasma cytokines and chemokines including interferon-γ, interleukin (IL)-4, IL-13, and IL-17A, markers of macrophage activation, and endothelial activation using multiplex assays and ELISA. Cytokines were grouped using Ward’s hierarchical clustering. Brachial artery flow-mediated dilation (FMD) and carotid plaque burden were determined using ultrasound. Multivariable linear regression and negative binomial regression analyses were used to assess the relationships of plasma biomarkers and endpoints adjusted for CVD risk factors. RESULTS: We identified three distinct clusters in PWH, one containing Th1/Th2/ILC1/ILC2 type cytokines, one with Th17/ILC3/macrophage-related cytokines, and a less specific third cluster. Lower FMD was associated with higher plasma IL-17A and macrophage inflammatory protein-1α. In contrast, IL-4, a Th2/ILC2 type cytokine, was associated with carotid plaque. When HIV-negative controls were added to the models clustering was more diffuse, and these associations were attenuated or absent. CONCLUSIONS: Th17/ILC3 and Th2/ILC2-mediated immune mechanisms may have distinct roles in endothelial dysfunction and atherosclerotic plaque formation, respectively, in PWH.

SummaryPersistent systemic inflammation in persons with HIV (PWH) is accompanied by an increased risk of metabolic disease. Yet, changes in the innate and adaptive immune system in PWH who develop metabolic disease remain poorly defined. Using unbiased approaches, we show that PWH with prediabetes/diabetes have a significantly higher proportion of circulating CD14+monocytes complexed to T cells. The complexed CD3+T cells and CD14+monocytes demonstrate functional immune synapses, increased expression of proinflammatory cytokines, and greater glucose utilization. Furthermore, these complexes harbor more latent HIV DNA compared to CD14+monocytes or CD4+T cells. Our results demonstrate that circulating CD3+CD14+T cell-monocyte pairs represent functional dynamic cellular interactions that likely contribute to inflammation and, in light of their increased proportion, may have a role in metabolic disease pathogenesis. These findings provide an incentive for future studies to investigate T cell-monocyte immune complexes as mechanistic in HIV cure and diseases of aging.Graphical AbstractHighlightsPersons with HIV and diabetes have increased circulating CD3+CD14+T cell-monocyte complexes.CD3+CD14+T cell-monocytes are a heterogenous group of functional and dynamic complexes.We can detect HIV in T cell-monocyte complexes.The proportion of CD3+CD14+T cell-monocyte complexes is positively associated with blood glucose levels and negatively with plasma IL-10 and CD4+T regulatory cells.

Persons with HIV (PWH) on long-term antiretroviral therapy (ART) have a higher incidence and prevalence of cardiometabolic diseases attributed, in part, to persistent inflammation despite viral suppression. In addition to traditional risk factors, immune responses to co-infections such as cytomegalovirus (CMV) may play an unappreciated role in cardiometabolic comorbidities and offer new potential therapeutic targets in a subgroup of individuals. We assessed the relationship of CX3CR1+, GPR56+, and CD57+/- T cells (termed CGC+) with comorbid conditions in a cohort of 134 PWH co-infected with CMV on long-term ART. We found that PWH with cardiometabolic diseases (non-alcoholic fatty liver disease, calcified coronary arteries, or diabetes) had higher circulating CGC+CD4+ T cells compared to metabolically healthy PWH. The traditional risk factor most correlated with CGC+CD4+ T cell frequency was fasting blood glucose, as well as starch/sucrose metabolites. While unstimulated CGC+CD4+ T cells, like other memory T cells, depend on oxidative phosphorylation for energy, they exhibited higher expression of carnitine palmitoyl transferase 1A compared to other CD4+ T cell subsets, suggesting a potentially greater capacity for fatty acid β-oxidation. Lastly, we show that CMV-specific T cells against multiple viral epitopes are predominantly CGC+. Together, this study suggests that among PWH, CGC+ CD4+ T cells are frequently CMV-specific and are associated with diabetes, coronary arterial calcium, and non-alcoholic fatty liver disease. Future studies should assess whether anti-CMV therapies could reduce cardiometabolic disease risk in some individuals.

OBJECTIVE: A higher proportion of circulating memory CD4(+) T cells is associated with prevalent diabetes mellitus in persons with HIV (PWH) and HIV-negative persons. We assessed whether circulating T cell subsets could also identify individuals who will subsequently develop diabetes. DESIGN: This is a longitudinal follow-up study of PWH and similar HIV-negative individuals from the Veterans Aging Cohort Study who provided peripheral mononuclear blood cells between 2005 and 2007. METHODS: We quantified T cell subsets using flow cytometry and functional assays to identify CD4(+) and CD8(+) naïve, activated, senescent, memory (central, effector, and effector RA(+)), and T(H)1, T(H)2, and T(H)17-phenotype cells. The occurrence of an incident diabetes diagnosis (i.e., after baseline blood draw) was adjudicated by a two-physician chart review. Cox proportional hazards models adjusted for traditional risk factors, cytomegalovirus serostatus, and plasma inflammatory biomarkers assessed the relationship between T cell subsets and incident diabetes. RESULTS: 1837 participants (1259 PWH) without diabetes at baseline were included; 69% were black, 95% were male, and median follow-up was 8.6 years. Higher baseline frequencies of CD4(+) T effector memory RA(+) (T(EMRA)) cells defined as CD45RA(+) CD27(−) (p=0.04) and senescent T cells defined as CD4(+) CD28(−) (p=0.04) were associated with incident diabetes in PWH only. CONCLUSIONS: Higher frequencies of CD4(+) T(EMRA) and CD4(+) CD28(−) T cells were associated with incident diabetes in PWH only after adjustment for other factors. Additional studies are necessary to assess whether these cells act in blood via inflammatory mediators or reflect T cell populations in metabolically active tissues.

Background Persons with HIV have a higher prevalence of coronary artery disease compared with their HIV‐negative counterparts. Earlier identification of subclinical atherosclerosis may provide a greater opportunity for cardiovascular disease risk reduction. We investigated coronary cross‐sectional area (CorCSA) by noncontrasted computed tomography imaging as a noninvasive measure of arterial remodeling among virally suppressed persons with HIV. Methods and Results We assessed 105 persons with HIV with a spectrum of cardiometabolic health. All participants underwent computed tomography imaging to assess the mean corCSA of the proximal left anterior descending artery and 28 participants underwent additional coronary computed tomography angiography. Partial Spearman rank correlations adjusted for cardiovascular disease risk factors were used to assess relationships of corCSA with anthropometric measurements, HIV‐related factors, and plasma cytokines. Mean corCSA measured by noncontrast computed tomography and coronary computed tomography angiography were strongly correlated (ρ=0.91, P P =0.005) and it correlated with participants' atherosclerotic cardiovascular disease risk score (ρ=0.35, P =0.01). After adjusting for established cardiovascular disease risk factors, we observed an inverse relationship between corCSA and CD4 + T‐cell count (ρ=−0.2, P =0.047). Removal of age from the model strengthened the relationships between corCSA and antiretroviral therapy duration (from ρ=0.19, P =0.08 to ρ=0.3, P =0.01). CorCSA was also inversely correlated with plasma IL‐10 (ρ=−0.25, P =0.03) but had no relationship with IL‐6 (ρ=0.11, P =0.4) or IL‐1β (ρ=0.08, P =0.5). Conclusions Positive coronary arterial remodeling, an imaging marker of subclinical atherosclerosis, is associated with a lower CD4 T‐cell count, lower circulating IL‐10, and possibly a longer antiretroviral therapy duration in persons with HIV. Registration Clinicaltrials.gov; Unique identifier: NCT04451980.

In this review, we focus on immune cell activation in obesity and cardiovascular disease, highlighting specific immune cell microenvironments present in individuals with atherosclerosis, non-ischemic heart disease, hypertension, and infectious diseases.Obesity and cardiovascular disease are intimately linked and often characterized by inflammation and a cluster of metabolic complications. Compelling evidence from single-cell analysis suggests that obese adipose tissue is inflammatory and infiltrated by almost all immune cell populations. How this inflammatory tissue state contributes to more systemic conditions such as cardiovascular and infectious disease is less well understood. However, current research suggests that changes in the adipose tissue immune environment impact an individual's ability to combat illnesses such as influenza and SARS-CoV2. Obesity is becoming increasingly prevalent globally and is often associated with type 2 diabetes and heart disease. An increased inflammatory state is a major contributor to this association. Widespread chronic inflammation in these disease states is accompanied by an increase in both innate and adaptive immune cell activation. Acutely, these immune cell changes are beneficial as they sustain homeostasis as inflammation increases. However, persistent inflammation subsequently damages tissues and organs throughout the body. Future studies aimed at understanding the unique immune cell populations in each tissue compartment impacted by obesity may hold potential for therapeutic applications.

Objective: Persons with HIV have double the risk of developing cardiovascular disease compared with the general population. A persistent and heightened immune response to cytomegalovirus coinfection may be one contributing factor, but the relationship between cytomegalovirus replication, virus-specific immune cells, and plaque burden is unclear. Approach and Results: We assessed the relationship between CD4 + T-cell subsets and carotid plaque burden in a cohort of 70 HIV-positive participants with sustained viral suppression on a single antiretroviral regimen and without known cardiovascular disease. We evaluated relationships between immune parameters, carotid plaque burden, and brachial artery flow-mediated vasodilation using multivariable linear and logistic regression models. We found that participants with carotid plaque had increased circulating CX3CR1 + ~GPR56 + ~CD57 + (ie, C~G~C) + CD4 + T cells ( P =0.03), which is a marker combination associated with antiviral and cytotoxic responses. In addition, a median of 14.4% (IQR, 4.7%–32.7%) of the C~G~C + CD4 + T-cells expressed antigen receptors that recognized a single cytomegalovirus glycoprotein-B epitope. Using immunofluorescence staining, we found that CX3CR1 + CD4 + T cells were present in coronary plaque from deceased HIV-positive persons. C~G~C + CD4 + T cells were also present in cells isolated from the aorta of HIV-negative donors. Conclusions: HIV-positive persons with carotid atheroma have a higher proportion of circulating CD4 + T-cells expressing the C~G~C surface marker combination associated with antiviral and cytotoxic responses. These cells can be cytomegalovirus-specific and are also present in the aorta.

Persons with human immunodeficiency virus (PWH) have subcutaneous adipose tissue (SAT) dysfunction related to antiretroviral therapy and direct viral effects, which may contribute to a higher risk of nonalcoholic fatty liver disease compared with human immunodeficiency virus–negative individuals. We assessed relationships between SAT expression of major adipocyte regulatory and lipid storage genes with hepatic and other ectopic lipid deposits in PWH. We enrolled 97 PWH on long‐term antiretroviral therapy with suppressed plasma viremia and performed computed tomography measurements of liver attenuation, a measure of hepatic steatosis, skeletal muscle (SM) attenuation, and the volume of abdominal subcutaneous, visceral, and pericardial adipose tissue. Whole SAT gene expression was measured using the Nanostring platform, and relationships with computed tomography imaging and fasting lipids were assessed using multivariable linear regression and network mapping. The cohort had a mean age of 47 years, body mass index of 33.4 kg/m2, and CD4 count of 492 cells/mm3. Lower liver attenuation, a marker of greater steatosis, was associated with differences in SAT gene expression, including lower lipoprotein lipase and acyl‐CoA dehydrogenase, and higher phospholipid transfer protein. Lower liver attenuation clustered with lower visceral adipose tissue (VAT) attenuation and greater VAT volume, pericardial fat volume and triglycerides, but no relationship was observed between liver attenuation and SAT volume, SM attenuation, or low‐density lipoprotein. Conclusion: Liver attenuation was associated with altered SAT expression of genes regulating lipid metabolism and storage, suggesting that SAT dysfunction may contribute to nonalcoholic fatty liver disease in PWH. SAT gene‐expression relationships were similar for VAT volume and attenuation, but not SM, indicating that ectopic lipid deposition may involve multiple pathways.

INTRODUCTION Markers of monocyte/macrophage activation and vascular inflammation are associated with HIV-related cardiovascular diseases (CVD) and mortality. We compared these markers among African people living with HIV (PLWH) and HIV-negative adults, and examined risk factors associated with elevated biomarkers (>75th percentile) in PLWH on antiretroviral therapy (ART). DESIGN Cross-sectional study. METHODS We measured serum concentrations of a gut integrity biomarker (intestinal-fatty acid binding protein), monocyte/macrophage activation biomarkers (soluble CD14 and CD163), and vascular inflammation biomarkers [soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular adhesion molecule 1 (sVCAM-1)]. We assessed the relationship of these inflammatory parameters with HIV, using logistic regression adjusting for traditional CVD risk factors. RESULTS Among the 541 participants, median age was 43 years and half were female. Among 275 PLWH, median CD4 T-cell count and duration of ART use was 509 cells/μl and 8 years, respectively. PLWH had significantly higher prevalence of elevated inflammatory biomarkers compared with HIV-negative individuals even after adjustment for traditional CVD risk factors. Compared with individuals without HIV, the prevalence of elevated biomarkers was highest among persons with detectable viral load and CD4 T-cell counts 200 cells/μl or less. In a subanalysis among PLWH, nadir CD4 T-cell count 200 cells/μl or less was associated with elevated soluble CD14 (sCD14); dyslipidemia with elevated sCD14, sICAM-1, and sVCAM-1; and overweight/obesity with reduced sCD14. Longer ART exposure (>4 years) was associated with reduced sVCAM-1 and sICAM-1. CONCLUSION HIV and not traditional CVD risk factors is a primary contributor of monocyte/macrophage activation and inflammation despite ART. Anti-inflammatory therapies in addition to ART may be necessary to reduce these immune dysregulations and improve health outcomes of African PLWH.

OBJECTIVES/HYPOTHESIS Characterization of the localized adaptive immune response in the airway scar of patients with idiopathic subglottic stenosis (iSGS). STUDY DESIGN Basic Science. METHODS Utilizing 36 patients with subglottic stenosis (25 idiopathic subglottic stenosis [iSGS], 10 iatrogenic post-intubation stenosis [iLTS], and one granulomatosis with polyangiitis [GPA]) we applied immunohistochemical and immunologic techniques coupled with RNA sequencing. RESULTS iSGS, iLTS, and GPA demonstrate a significant immune infiltrate in the subglottic scar consisting of adaptive cell subsets (T cells along with dendritic cells). Interrogation of T cell subtypes showed significantly more CD69+ CD103+ CD8+ tissue resident memory T cells (TRM ) in the iSGS airway scar than iLTS specimens (iSGS vs. iLTS; 50% vs. 28%, P = .0065). Additionally, subglottic CD8+ clones possessed T-cell receptor (TCR) sequences with known antigen specificity for viral and intracellular pathogens. CONCLUSIONS The human subglottis is significantly enriched for CD8+ tissue resident memory T cells in iSGS, which possess TCR sequences proven to recognize viral and intracellular pathogens. These results inform our understanding of iSGS, provide a direction for future discovery, and demonstrate immunologic function in the human proximal airway. Laryngoscope, 131:610-617, 2021.

Subcutaneous adipose tissue (SAT) is a critical regulator of systemic metabolic homeostasis. Persons with HIV (PWH) have an increased risk of metabolic diseases and significant alterations in the SAT immune environment compared with the general population. We generated a comprehensive SAT atlas to characterize cellular compositional and transcriptional changes in 59 PWH with a spectrum of metabolic health. Glucose intolerance was associated with increased lipid-associated macrophages and CD4+and CD8+T effector memory cells, and decreased perivascular macrophages. We observed a coordinated intercellular regulatory program which enriched for genes related to inflammation and lipid-processing across multiple cell types as glucose intolerance increased. Increased CD4+effector memory tissue resident cells most strongly associated with altered expression of adipocyte genes critical for lipid metabolism and cellular regulation. Many of these findings were present in a separate group of 32 diabetic HIV-negative persons, suggesting these changes are not specific to HIV.

Pre-existing pathogen-specific memory T cell responses can contribute to multiple adverse outcomes including autoimmunity and drug hypersensitivity. How the specificity of the T cell receptor (TCR) is subverted or seconded in many of these diseases remains unclear. Here, we apply abacavir hypersensitivity (AHS) as a model to address this question because the disease is linked to memory T cell responses and the HLA risk allele, HLA-B*57:01, and the initiating insult, abacavir, are known. To investigate the role of pathogen-specific TCR specificity in mediating AHS we performed a genome-wide screen for HLA-B*57:01 restricted T cell responses to Epstein-Barr virus (EBV), one of the most prevalent human pathogens. T cell epitope mapping revealed HLA-B*57:01 restricted responses to 17 EBV open reading frames and identified an epitope encoded by EBNA3C. Using these data, we cloned the dominant TCR for EBNA3C and a previously defined epitope within EBNA3B. TCR specificity to each epitope was confirmed, however, cloned TCRs did not cross-react with abacavir plus self-peptide. Nevertheless, abacavir inhibited TCR interactions with their cognate ligands, demonstrating that TCR specificity may be subverted by a drug molecule. These results provide an experimental road map for future studies addressing the heterologous immune responses of TCRs including T cell mediated adverse drug reactions.

While antiretroviral therapy (ART) has proven effective in suppressing viremia and disease progression among people living with human immunodeficiency virus (HIV; PLWH), suboptimal CD4+ T cell reconstitution remains a major obstacle in nearly 30% of ART-treated individuals. Epidemiological studies demonstrate that obesity, or a body mass index (BMI) ≥ 30 kg/m2, is positively correlated with greater CD4+ T cell recovery in PLWH on ART. Leptin is a known immunomodulator that is produced in proportion to fat mass and is increased in obese individuals, including PLWH. We hypothesized that CD4+ T cells from obese PLWH have increased cell proliferation and cytokine production compared to cells from lean PLWH, potentially modulated by differential effects of leptin signaling. To test this hypothesis, peripheral blood mononuclear cells from obese and lean PLWH with long-term virologic suppression on the same ART regimen were pretreated with recombinant leptin and then stimulated with anti-CD3/CD28 or PMA/ionomycin to measure Ki67 expression, leptin receptor (LepR) surface expression and cytokine production. In the absence of leptin, Ki67 expression and IL-17A production were significantly higher in CD4+ T cells from obese compared to lean PLWH. However, LepR expression was significantly lower on CD4+ T cells from obese compared to lean PLWH. After leptin treatment, Ki67 expression was significantly increased in CD4+ T cells from obese PLWH compared to the lean participants. Leptin also increased IL-17A production in CD4+ T cells from obese healthy controls. In contrast, leptin decreased IL-17A production in CD4+ T cells from both obese and lean PLWH. Combined, these results demonstrate that obesity is associated with greater CD4+ T cell proliferation among PLWH, and that higher circulating leptin levels in obesity may contribute to improved CD4+ T reconstitution in PLWH initiating ART.

Salt sensitivity of blood pressure is an independent predictor of death due to cardiovascular events. Diagnosis of salt-sensitivity is not feasible in the clinic, making it difficult to investigate therapeutic strategies. We hypothesized that NLRP3-inflammasome and IL-1β production in monocytes plays a role in salt-sensitive hypertension. We phenotyped salt-sensitivity of blood pressure using an acute inpatient Weinberger protocol of an isocaloric high salt diet and rapid intravenous salt-loading, followed by low salt diet and furosemide-induced salt-depletion. Ambulatory blood pressure was continuously monitored and averaged for the days of salt-loading and salt-depletion. Blood samples were obtained at baseline, salt-loading, and after salt-depletion. Median age was 54 years (44-55), 3 of the 5 subjects were female, screening systolic blood pressure was 140 mmHg (134-148), diastolic blood pressure was 88 mmHg (84-99), and BMI was 35 kg/m 2 (30-39). Using cell hashing and ECCITE-seq analysis, we profiled transcriptomes in multiple immune cell types using antibody-derived tags (ADTs). UMAP clustering of different cell types were identified by ADTs including monocyte markers CD14 and CD16. Interestingly, UMAP visualization of CD14+ and CD16+ clusters indicated a greater decrease in CD14+ clusters after salt-depletion in the salt-resistant subjects than the salt-sensitive; however the salt-sensitive subjects had a greater decrease in CD16+ clusters than the salt-resistant group after both salt-loading and salt-depletion. These data were confirmed using flow cytometry. Unlike in salt-resistant participants, we found that within monocyte clusters, salt-sensitivity was associated with down regulation of the inflammasome components NLRP3 (0.386 ± 1.18 vs. 0.197 ± 0.778) and IL-1β (0.858 ± 2.32 vs. 0.159 ± 0.925) following salt-depletion. Using flow cytometry, we found Δ% isoLG+ CD14+/CD16+ monocytes correlated with salt-sensitivity of blood pressure (r=0.88, 95% CI, p=0.05). These results suggest that the inflammasome and monocyte activation are dynamically regulated by dietary salt in vivo and can serve as a potential diagnostic biomarker for salt-sensitivity of blood pressure.

Adipose tissue contains a complex immune environment and is a central contributor to heightened systemic inflammation in obese persons. Epoxyeicosatrienoic acids (EETs) are lipid signaling molecules that decrease inflammation in obese animals, but their effect on inflammation in humans is unknown. The enzyme soluble epoxide hydrolase (sEH) hydrolyzes EETs to less active diols, and we hypothesized that pharmacologic sEH inhibition would decrease adipose inflammation in obese individuals. We treated obese prediabetic adults with the sEH inhibitor GSK2256294 versus placebo in a crossover design, collected subcutaneous abdominal adipose tissue via lipoaspiration and characterized the tissue T cell profile. Treatment with GSK2256294 decreased the percentage of pro-inflammatory T cells producing interferon-gamma (IFNγ), but not interleukin (IL)-17A, and decreased the amount of secreted tumor necrosis factor-alpha (TNFα). Understanding the contribution of the EET/sEH pathway to inflammation in obesity could lead to new strategies to modulate adipose and systemic inflammation.

OBJECTIVE: Fat redistribution from subcutaneous adipose tissue (SAT) to the abdominal viscera, pericardium, liver and skeletal muscle contributes to the rising burden of cardiometabolic disease among persons with HIV (PWH). Prior studies found SAT inflammation in PWH impairs lipid storage and persists despite plasma viral suppression on antiretroviral therapy (ART). In this study, we identify SAT immune-related genes associated with ectopic fat deposition in PWH on long-term ART. DESIGN AND METHODS: A total of 92 PWH with well-controlled viremia underwent computed tomography (CT) imaging and abdominal SAT biopsy for gene expression analysis. SAT gene expression was measured using a NanoString panel of 255 immune-related genes. Associations between gene expression and CT measurements of the volume and attenuation (radiodensity) of metabolically relevant ectopic fat depots were assessed using multivariable linear regression and network analysis. RESULTS: Greater SAT volume was associated with higher visceral and pericardial adipose tissue volume, but lower skeletal muscle attenuation. Lower SAT attenuation, a measure of lipid content, was associated with lower VAT attenuation. Hierarchical clustering identified a subset of macrophage-related genes in SAT, including CCL2, CCL22, CCL13, CCR1, CD86, CD163, IL-6, IL-10, MRC1, and TREM2, that were associated with increased lipid deposition in multiple ectopic depots. CONCLUSION: Altered expression of macrophage-related genes in SAT is associated with differences in ectopic fat depot morphometrics among PWH on long-term ART, including in the pericardial and visceral compartments. These findings provide basis for future studies to assess host, virus, and treatment factors shaping the SAT immune environment and its effects on morphometric changes and metabolic comorbidities in PWH.

Despite the anticipated growth in the global burden of obesity especially in low-income countries, limited data exist on the contribution of obesity to cardiometabolic diseases in Africa. We examined population-based samples of Kenyan adults who participated in the 2015 national chronic disease risk factor surveillance survey. Weight and height were measured, and body mass index (BMI) was calculated and used as a measure for general obesity. Waist circumference (WC), a clinical measure of central obesity was also measured. Logistic regression was used to assess the association between obesity with hypertension, diabetes, and dyslipidemia risk. Of the 4276 participants, the median (IQR) age was 36 (27–47) years, 41% were men. One-third (37%) of the participants were centrally obese, whereas 10% were generally obese. The odds for overweight and general obesity were highest among females, adults >40 years, and those in the highest wealth quartile. Central and general obesity, assessed by WC and BMI, were associated with hypertension and dyslipidemia but not diabetes for both sexes. Compared with adults of normal weight, individuals with a BMI of ≥30 kg/m2 had an odds ratio of 2.39 (95% confidence interval [CI], 1.82–3.12) for hypertension and 2.24 (95% CI, 1.70–2.96) for dyslipidemia. Obesity prevalence is high in Kenya and is associated with hypertension and dyslipidemia but not diabetes. Our findings indicate an urgent need to develop public health interventions to address obesity and prevent the development of comorbid conditions.

Objectives: Heightened systemic inflammation is common in obese individuals and persons with HIV (PWH) and is independently associated with an increased risk of cardiovascular diseases (CVDs). We investigated the combined effect of central obesity, a surrogate measure of visceral fat and HIV on circulating levels of inflammatory cytokines among Kenyan adults. Design: A cross-sectional study. Methods: We analysed and compared data from 287 virally suppressed PWH and 277 noninfected Kenyan adults, including biomarkers of gut epithelial dysfunction (intestinal fatty acid binding protein), monocyte activation (soluble CD163 and CD14) and inflammation [interleukin (IL)-1β, IL-6, TNF-α and hsCRP] by HIV/central obesity status (HIV-positive/obese, HIV-negative/obese, HIV-positive/nonobese and HIV-negative/nonobese). Central obesity was defined as waist circumference more than 80 cm for women and more than 94 cm for men. We assessed the association of HIV/obesity status with elevated biomarkers (>75th percentile) using logistic regression. Results: Median age for participants was 44 years and 37% were centrally obese. Levels of all biomarkers were higher among the HIV-positive/obese compared with the HIV-negative/nonobese (P

OBJECTIVE: Persons with human immunodeficiency virus (HIV) have double the risk of developing cardiovascular disease (CVD) compared to the general population. A persistent and heightened immune response to cytomegalovirus (CMV) co-infection may be one contributing factor, but the relationship between CMV replication, virus-specific immune cells and plaque burden is unclear. APPROACH AND RESULTS: We assessed the relationship between CD4(+) T-cell subsets and carotid plaque burden in a cohort of 70 HIV-positive participants with sustained viral suppression on a single antiretroviral regimen and without known CVD. We evaluated relationships between immune parameters, carotid plaque burden, and brachial artery flow-mediated vasodilation (FMD) using multivariable linear and logistic regression models. We found that participants with carotid plaque had increased circulating CX3CR1(+)~GPR56(+)~CD57(+) (i.e., C~G~C)(+) CD4(+) T cells (p=0.03), which is a marker combination associated with anti-viral and cytotoxic responses. In addition, a median of 14.4% [IQR 4.7, 32.7%] of the C~G~C(+) CD4(+) T-cells expressed antigen receptors that recognized a single CMV glycoprotein-B epitope. Notably, using immunofluorescence staining we found that CX3CR1(+) CD4(+) T-cells were present in coronary plaque from deceased HIV-positive persons. C-G-C(+) CD4(+) T cells were also present in cells isolated from the aorta of HIV-negative donors. CONCLUSIONS: HIV-positive persons with carotid atheroma have a higher proportion of circulating CD4(+) T-cells expressing the C~G~C surface marker combination associated with antiviral and cytotoxic responses. These cells can be CMV-specific and are also present in the aorta.

BackgroundPeople living with human immunodeficiency virus (HIV) may have numerous risk factors for acquiring coronavirus disease 2019 (COVID-19) and developing severe outcomes, but current data are conflicting.MethodsHealth-care providers enrolled consecutively, by nonrandom sampling, people living with HIV (PWH) with lab-confirmed COVID-19, diagnosed at their facilities between 1 April and 1 July 2020. Deidentified data were entered into an electronic Research Electronic Data Capture (REDCap) system. The primary endpoint was a severe outcome, defined as a composite endpoint of intensive care unit (ICU) admission, mechanical ventilation, or death. The secondary outcome was the need for hospitalization.ResultsThere were 286 patients included; the mean age was 51.4 years (standard deviation, 14.4), 25.9% were female, and 75.4% were African American or Hispanic. Most patients (94.3%) were on antiretroviral therapy, 88.7% had HIV virologic suppression, and 80.8% had comorbidities. Within 30 days of testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), 164 (57.3%) patients were hospitalized, and 47 (16.5%) required ICU admission. Mortality rates were 9.4% (27/286) overall, 16.5% (27/164) among those hospitalized, and 51.5% (24/47) among those admitted to an ICU. The primary composite endpoint occurred in 17.5% (50/286) of all patients and 30.5% (50/164) of hospitalized patients. Older age, chronic lung disease, and hypertension were associated with severe outcomes. A lower CD4 count (ConclusionsSevere clinical outcomes occurred commonly in PWH with COVID-19. The risks for poor outcomes were higher in those with comorbidities and lower CD4 cell counts, despite HIV viral suppression.Clinical Trials RegistrationNCT04333953.

Objective: Chronic inflammation contributes to the high burden of cardiovascular disease (CVD) in persons with HIV (PWH). HIV has broad effects on immune function, including CD4+T-helper cells which secrete cytokines that regulate innate and adaptive immune pathways implicated in CVD progression. At present, the relationship between T-helper cell responses and CVD in PWH is not well defined. Methods: We recruited 70 PWH on a single antiretroviral regimen (efavirenz, tenofovir, and emtricitabine) with at least 12 months of suppressed viremia. We quantified 19 plasma cytokines and chemokines including interferon (IFN)-γ, interleukin (IL)-2, 4, 13, and 17A, markers of macrophage activation, and markers of endothelial activation using multiplex assays and ELISA. Cytokines were grouped using Ward's hierarchical clustering. Brachial artery flow-mediated dilation (FMD), as a marker of endothelial function, and carotid plaque burden were measured using ultrasound. Multivariable linear regression was used to assess the relationships of biomarkers and endpoints with adjustment for CVD risk factors. Results: We identified three distinct cytokine clusters, one containing Th1/Th2 cytokines, one with Th17-type and macrophage-related cytokines, and a third less specific. Lower brachial artery FMD was associated with higher plasma IL-17A and macrophage inflammatory protein 1α, while higher soluble vascular cell adhesion molecule-1 and intercellular cell adhesion molecule 1 were associated with higher IL-17A, and IL-5. In contrast, IL-10 and the Th2-type cytokine IL-4 were associated with greater plaque burden. Conclusions: Distinct Th2 and Th17-mediated immune mechanisms may have a role at differing stages of atherosclerotic vascular disease in PWH.

BackgroundChronic innate and adaptive immune activation may contribute to high prevalence of cardiovascular disease in persons living with HIV (PLWH).MethodsWe assessed coronary plaques from deceased PLWH (n=6) and HIV-negative (n=6) persons matched by age and gender. Formalin-fixed, paraffin-embedded 5μm thick sections were processed using Movat, hematoxylin and eosin, immunohistochemical and immunofluorescence stains. Immune cell populations were measured using surface antibodies, and immune-related protein expression from macrophage rich, T-cell rich and perivascular adipose tissue regions using GeoMx® digital spatial profiling.ResultsCoronary plaques from PLWH and HIV-negative persons had similar plaque area and percent stenosis. Percent CD163+ cells as measured by immunohistochemical staining was significantly higher in PLWH, median 0.29% (IQR 0.11-0.90) vs. 0.01% (IQR 0.0013-0.11) in HIV-negative plaque, p = 0.02 (Figure 1A). Other surface markers of innate cells (CD68 +, p=0.18), adaptive immune cells (CD3+, p=0.39; CD4+, p=0.09; CD8+, p=0.18) and immune trafficking markers (CX3CR1+, p=0.09) within the coronary plaque trended higher in HIV-positive plaques but did not reach statistical significance. GeoMx® digital spatial profiling showed higher differential protein expression of CD163 (scavenger receptor for hemoglobin-haptoglobin complex), stimulator of interferon gamma (STING, a cytosolic DNA sensor), CD25 and granzyme-B in the HIV-positive compared to HIV-negative, pConclusionsIncreased inflammation within the coronary plaques of PLWH is characterized by more innate and adaptive immune cells. Higher STING expression in PLWH suggests that immune response to viral antigens within the plaque might be a driver above other stimulants. STING inhibitors are available and could be investigated as a future therapeutic target in PWH if these results are replicated with a larger number of plaques.Graphical AbstractHighlightsImmunohistochemical and fluorescent stains combined with GeoMx® digital spatial profiling allowed for deep characterization of immune cells within intact coronary plaques and perivascular adipose tissueCoronary plaques from HIV-positive persons had higher proportion of CD163+ immune cells compared to HIV-negative personsDifferential protein expression of immune-rich regions of interest within intact 5μm sections of coronary plaques revealed higher levels of stimulator of interferon gamma (STING) in HIV-positive persons

PURPOSE OF REVIEW: The proportion of overweight and obese persons with HIV (PWH) has increased since the introduction of antiretroviral therapy (ART). We aim to summarize recent literature on risks of weight gain, discuss adipose tissue changes in HIV and obesity, and synthesize current understanding of how excess adiposity and HIV contribute to metabolic complications. RECENT FINDINGS: Recent studies have implicated contemporary ART regimens, including use of integrase strand transfer inhibitors and tenofovir alafenamide, as a contributor to weight gain, though the mechanisms are unclear. Metabolic dysregulation is linked to ectopic fat and alterations in adipose immune cell populations that accompany HIV and obesity. These factors contribute to an increasing burden of metabolic diseases in the aging HIV population. SUMMARY: Obesity compounds an increasing burden of metabolic disease among PWH, and understanding the role of fat partitioning and HIV- and ART-related adipose tissue dysfunction may guide prevention and treatment strategies.

Adverse drug reactions (ADRs) are a significant source of patient morbidity and mortality and represent a major burden to health care systems and drug development. Up to 50% of such reactions are preventable. Although many ADRs can be predicted based on the on-target pharmacologic activity, ADRs arising from drug interactions with off-target receptors are recognized. Off-target ADRs include the immune-mediated ADRs (IM-ADRs) and pharmacologic drug effects. In this review, we discuss what is known about the immunogenetics and pathogenesis of IM-ADRs and the hypothesized role of heterologous immunity in the development of IM-ADRs.

Select CMV epitopes drive life-long CD8+ T cell memory inflation, but the extent of CD4 memory inflation is poorly studied. CD4+ T cells specific for human CMV (HCMV) are elevated in HIV+ HCMV+ subjects. To determine whether HCMV epitope–specific CD4+ T cell memory inflation occurs during HIV infection, we used HLA-DR7 (DRB1*07:01) tetramers loaded with the glycoprotein B DYSNTHSTRYV (DYS) epitope to characterize circulating CD4+ T cells in coinfected HLA-DR7+ long-term nonprogressor HIV subjects with undetectable HCMV plasma viremia. DYS-specific CD4+ T cells were inflated among these HIV+ subjects compared with those from an HIV− HCMV+ HLA-DR7+ cohort or with HLA-DR7–restricted CD4+ T cells from the HIV-coinfected cohort that were specific for epitopes of HCMV phosphoprotein-65, tetanus toxoid precursor, EBV nuclear Ag 2, or HIV gag protein. Inflated DYS-specific CD4+ T cells consisted of effector memory or effector memory–RA+ subsets with restricted TCRβ usage and nearly monoclonal CDR3 containing novel conserved amino acids. Expression of this near-monoclonal TCR in a Jurkat cell–transfection system validated fine DYS specificity. Inflated cells were polyfunctional, not senescent, and displayed high ex vivo levels of granzyme B, CX3CR1, CD38, or HLA-DR but less often coexpressed CD38+ and HLA-DR+. The inflation mechanism did not involve apoptosis suppression, increased proliferation, or HIV gag cross-reactivity. Instead, the findings suggest that intermittent or chronic expression of epitopes, such as DYS, drive inflation of activated CD4+ T cells that home to endothelial cells and have the potential to mediate cytotoxicity and vascular disease.

Persons with HIV (PWH) are at high risk for diabetes mellitus. Adipose tissue T cells are a central regulator of inflammation and adipocyte function, and the known establishment of a HIV reservoir in adipose could contribute to metabolic dysregulation. Here, we show that CD4+ T cell subsets increased in the adipose of diabetic PWH, specifically CD69+ and CD69lo CD57+ GPR56+ CX3CR1+, are clonally expanded with shared T cell receptors, suggesting a common lineage. We observed that both CD69+ and CX3CR1+ CD4+ T cells have transcriptomes consistent with a TH1 profile in diabetics versus TH2 in non-diabetics. CX3CR1+ CD4+ T cells from diabetic PWH also have increased expression of genes in innate immune pathways, not present in CD69+ cells, suggesting functional differences. This study sets the stage for future investigations to determine whether viral antigens in adipose tissue may promote clonal expansion of pro-inflammatory CX3CR1+ and CD69+ CD4+ T cells.

Summary Persons with HIV are at increased risk for diabetes mellitus compared with individuals without HIV. Adipose tissue is an important regulator of glucose and lipid metabolism, and adipose tissue T cells modulate local inflammatory responses and, by extension, adipocyte function. Persons with HIV and diabetes have a high proportion of CX3CR1+ GPR56+ CD57+ (C-G-C+) CD4+ T cells in adipose tissue, a subset of which are cytomegalovirus specific, whereas individuals with diabetes but without HIV have predominantly CD69+ CD4+ T cells. Adipose tissue CD69+ and C-G-C+ CD4+ T cell subsets demonstrate higher receptor clonality compared with the same cells in blood, potentially reflecting antigen-driven expansion, but C-G-C+ CD4+ T cells have a more inflammatory and cytotoxic RNA transcriptome. Future studies will explore whether viral antigens have a role in recruitment and proliferation of pro-inflammatory C-G-C+ CD4+ T cells in adipose tissue of persons with HIV., Graphical Abstract, Highlights Adipose tissue memory CD4+ T cells are frequently CD69+ in persons with diabetes Persons with HIV and diabetes have more CX3CR1+ GPR56+ CD57+ (C-G-C+) CD4+ T cells Adipose tissue C-G-C+ CD4+ T cells and CD69+ CD4+ T cells are clonally expanded C-G-C+ CD4+ T cells are often CMV specific and have more inflammatory transcriptomes, Wanjalla et al. demonstrate that adipose tissue in persons with HIV and diabetes includes a large proportion of clonally expanded, inflammatory, and frequently CMV-specific CX3CR1+ GPR56+ CD57+ (C-G-C+) CD4+ T cells. These cells may contribute to the altered adipocyte function and elevated risk of metabolic disease observed among persons with HIV.

Adipose tissue comprises one of the largest organs in the body and performs diverse functions including energy storage and release, regulation of appetite and other neuroendocrine signaling, and modulation of immuity, among others. Adipocytes reside in a complex compartment where antigen, antigen presenting cells, innate immune cells, and adaptive immune cells interact locally and exert systemic effects on inflammation, circulating immune cell profiles, and metabolic homeostasis. T lymphocytes are a major component of the adipose tissue milieu which are altered in disease states such as obesity and human immunodeficiency virus (HIV) infection. While obesity, HIV infection, and simian immunodeficiency virus (SIV; a non-human primate virus similar to HIV) infection are accompanied by enrichment of CD8+ T cells in the adipose tissue, major phenotypic differences in CD4+ T cells and other immune cell populations distinguish HIV/SIV infection from obesity. Furthermore, DNA and RNA species of HIV and SIV can be detected in the stromal vascular fraction of visceral and subcutaneous adipose tissue, and replication-competent HIV resides in local CD4+ T cells. Here, we review studies of adipose tissue CD4+ and CD8+ T cell populations in HIV and SIV, and contrast the findings with those reported in obesity.

Chronic T cell activation and accelerated immune senescence are hallmarks of HIV infection, which may contribute to the increased risk of cardiometabolic diseases in people living with HIV (PLWH). T lymphocytes play a central role in modulating adipose tissue inflammation and, by extension, adipocyte energy storage and release. Here, we assessed the CD4+ and CD8+ T cell profiles in the subcutaneous adipose tissue (SAT) and blood of non-diabetic (n = 9; fasting blood glucose [FBG] < 100 mg/dL), pre-diabetic (n = 8; FBG = 100–125 mg/dL) and diabetic (n = 9; FBG ≥ 126 mg/dL) PLWH, in addition to non- and pre-diabetic, HIV-negative controls (n = 8). SAT was collected by liposuction and T cells were extracted by collagenase digestion. The proportion of naïve (TNai) CD45RO−CCR7+, effector memory (TEM) CD45RO+CCR7−, central memory (TCM) CD45RO+CCR7+, and effector memory revertant RA+(TEMRA) CD45RO−CCR7− CD4+ and CD8+ T cells were measured by flow cytometry. CD4+ and CD8+ TEM and TEMRA were significantly enriched in SAT of PLWH compared to blood. The proportions of SAT CD4+ and CD8+ memory subsets were similar across metabolic status categories in the PLWH, but CD4+ T cell expression of the CD69 early-activation and tissue residence marker, particularly on TEM cells, increased with progressive glucose intolerance. Use of t-distributed Stochastic Neighbor Embedding (t-SNE) identified a separate group of predominantly CD69lo TEM and TEMRA cells co-expressing CD57, CX3CR1, and GPR56, which were significantly greater in diabetics compared to non-diabetics. Expression of the CX3CR1 and GPR56 markers indicate these TEM and TEMRA cells may have anti-viral specificity. Compared to HIV-negative controls, SAT from PLWH had an increased CD8:CD4 ratio, but the distribution of CD4+ and CD8+ memory subsets was similar irrespective of HIV status. Finally, whole adipose tissue from PLWH had significantly higher expression of TLR2, TLR8, and multiple chemokines potentially relevant to immune cell homing compared to HIV-negative controls with similar glucose tolerance.

We aim to provide an in-depth review of recent literature highlighting the role of inflammation involving the adipose tissue, liver, skeletal muscles, and gastrointestinal tract in the development of metabolic complications among persons living with HIV (PLWH). Recent studies in PLWH have demonstrated a significant association between circulating inflammatory markers and development of insulin resistance and metabolic complications. In adipose tissue, pro-inflammatory cytokine expression inhibits adipocyte insulin signaling, which alters lipid and glucose homeostasis. Increased lipolysis and lipogenesis elevate levels of circulating free fatty acids and promote ectopic fat deposition in liver and skeletal muscles. This leads to lipotoxicity characterized by a pro-inflammatory response with worsening insulin resistance. Finally, HIV is associated with gastrointestinal tract inflammation and changes in the gut microbiome resulting in reduced diversity, which is an additional risk factor for diabetes. Metabolic complications in PLWH are in part due to chronic, multisite tissue inflammation resulting in dysregulation of glucose and lipid trafficking, utilization, and storage.

Background Traditional cardiovascular disease (CVD) risk factors contribute to increase risk of CVD in people living with HIV (PLWH). Of all world regions, sub-Saharan Africa has the highest prevalence of HIV yet little is known about PLWH’s CVD knowledge and self- perceived risk for coronary heart disease (CHD). In this study, we assessed PLWH’s knowledge, perception and attitude towards cardiovascular diseases and their prevention. Methods We conducted a cross-sectional study in the largest HIV care program in western Kenya. Trained research assistants used validated questionnaires to assess CVD risk patterns. We used logistic regression analysis to identify associations between knowledge with demographic variables, HIV disease characteristics, and individuals CVD risk patterns. Results There were 300 participants in the study; median age (IQR) was 40 (33–46) years and 64 % women. The prevalence of dyslipidemia, overweight and obesity were 70 %, 33 % and 8 %, respectively. Participant’s knowledge of risk factors was low with a mean (SD) score of 1.3 (1.3) out of possible 10. Most (77.7 %) could not identify any warning signs for heart attack. Higher education was a strong predictor of CVD risk knowledge (6.72, 95 % CI 1.98-22.84, P

Our studies have concentrated on elucidating the role of the signaling protein Sin in T-lymphocyte function. We have previously shown that Sin overexpression inhibits T-lymphocyte development and activation. Here we show that Sin-deficient mice exhibit exaggerated immune responses characterized by enhanced cytokine secretion and T-cell-dependent antibody production. Excessive T-cell responses in young mice correlate with spontaneous development of inflammatory lesions in different organs of aged Sin(-/-) mice, particularly the small intestine. The intestinal inflammation is characterized by T- and B-cell infiltrates in the lamina propria, which correlate with crypt enlargement and marked villus expansion and/or damage. Similar to the human intestinal inflammatory disorder Crohn's disease (CD), and in contrast to most mouse models of mucosal inflammation, inflammatory lesions in the gastrointestinal tract of Sin(-/-) mice are restricted to the small bowel. Taken together, these results suggest that Sin regulates immune system and T-lymphocyte function and that immune system dysfunction in the absence of Sin may underlie the pathogenesis of tissue-specific inflammation and enteropathies such as CD.

Inflammatory cytokines have a significant role in altering the innate and adaptive arms of immune responses. Here, we analyzed the effect of GM-CSF on a RABV-vaccine vector co-expressing HIV-1 Gag. To this end, we immunized mice with RABV expressing HIV-1 Gag and GM-CSF and analyzed the primary and recall CD8+ T cell responses. We observed a statistically significant increase in antigen presenting cells (APCs) in the spleen and draining lymph nodes in response to GM-CSF. Despite the increase in APCs, the primary and memory anti HIV-1 CD8+ T cell response was significantly lower. This was partly likely due to lower levels of proliferation in the spleen. Animals treated with GM-CSF neutralizing antibodies restored the CD8+ T cell response. These data define a role of GM-CSF expression, in the regulation of the CD8+ T cell immune responses against RABV and has implications in the use of GM-CSF as a molecular adjuvant in vaccine development.

Until recently, single-stranded negative sense RNA viruses (ssNSVs) were one of only a few important human viral pathogens, which could not be created from cDNA. The inability to manipulate their genomes hindered their detailed genetic analysis. A key paper from Conzelmann's laboratory in 1994 changed this with the publication of a method to recover rabies virus (RABV) from cDNA. This discovery not only dramatically changed the broader field of ssNSV biology but also opened a whole new avenue for studying RABV pathogenicity, developing novel RABV vaccines as well a new generation of RABV-based vaccine vectors, and creating research tools important in neuroscience such as neuronal tracing.

Dendritic cells (DC) are the most potent antigen presenting cells whose ability to interact with T cells, B cells and NK cells has led to their extensive use in vaccine design. Here, we designed a DC-based HIV-1 vaccine using an attenuated rabies virus vector expressing HIV-1 Gag (RIDC-Gag). To test this, BALB/c mice were immunized with RIDC-Gag, and the primary, secondary as well as humoral immune responses were monitored. Our results indicate that RIDC-Gag stimulated HIV-1 Gag-specific immune responses in mice. When challenged with vaccinia virus (VV) expressing HIV-1 Gag, they elicited a potent Gag-specific recall response characterized by CD8+ T cells expressing multiple cytokines that were capable of specifically lysing Gag-pulsed target cells. Moreover, RIDC-Gag also enhanced CD8+ T cell responses via a homologous prime-boost regimen. These results show that a DC-based vaccine using live RV is immunogenic and a potential candidate for a therapeutic HIV-1 vaccine.

Summary Leukocyte migration and trafficking is dynamically regulated by various chemokine and adhesion molecules and is vital to the proper function of the immune system. We describe a role for the Cas and Hef-1-associated signal transducer in hematopoietic cells (Chat-H) as a critical regulator of T lymphocyte migration, by using lentivirus-mediated RNA interference (RNAi). Impaired migration of Chat-H-depleted cells coincided with defective inside-out signaling shown by diminished chemokine-induced activation of the Rap-1 GTPase and integrin-mediated adhesion. Localization of Chat-H to the plasma membrane, association with its binding partner Crk-associated substrate in lymphocytes (CasL), and Chat-H-mediated CasL serine-threonine phosphorylation were required for T cell migration. These results identify Chat-H as a critical signaling intermediate acting upstream of Rap1 to regulate chemokine-induced adhesion and migration.

This study analyzed a heterologous prime-boost vaccine approach against HIV-1 using three different antigenically unrelated negative-stranded viruses (NSV) expressing HIV-1 Gag as vaccine vectors: rabies virus (RABV), vesicular stomatitis virus (VSV) and Newcastle disease virus (NDV). We hypothesized that this approach would result in more robust cellular immune responses than those achieved with the use of any of the vaccines alone in a homologous prime-boost regimen. To this end, we primed BALB/c mice with each of the NSV-based vectors. Primed mice were rested for thirty-five days after which we administered a second immunization with the same or heterologous NSV-Gag viruses. The magnitude and quality of the Gag-specific CD8(+) T cells in response to these vectors post boost were measured. In addition, we performed challenge experiments using vaccinia virus expressing HIV-1 Gag (VV-Gag) thirty-three days after the boost inoculation. Our results showed that the choice of the vaccine used for priming was important for the detected Gag-specific CD8(+) T cell recall responses post boost and that NDV-Gag appeared to result in a more robust recall of CD8(+) T cell responses independent of the prime vaccine used. However, the different prime-boost strategies were not distinct for the parameters studied in the challenge experiments using VV-Gag but did indicate some benefits compared to single immunizations. Taken together, our data show that NSV vectors can individually stimulate HIV-Gag specific CD8(+) T cells that are effectively recalled by other NSV vectors in a heterologous prime-boost approach. These results provide evidence that RABV, VSV and NDV can be used in combination to develop vaccines needing prime-boost regimens to stimulate effective immune responses.

As with many viruses, rabies virus (RABV) infection induces type I interferon (IFN) production within the infected host cells. However, RABV has evolved mechanisms by which to inhibit IFN production in order to sustain infection. Here we show that RABV infection of dendritic cells (DC) induces potent type I IFN production and DC activation. Although DCs are infected by RABV, the viral replication is highly suppressed in DCs, rendering the infection non-productive. We exploited this finding in bone marrow derived DCs (BMDC) in order to differentiate which pattern recognition receptor(s) (PRR) is responsible for inducing type I IFN following infection with RABV. Our results indicate that BMDC activation and type I IFN production following a RABV infection is independent of TLR signaling. However, IPS-1 is essential for both BMDC activation and IFN production. Interestingly, we see that the BMDC activation is primarily due to signaling through the IFNAR and only marginally induced by the initial infection. To further identify the receptor recognizing RABV infection, we next analyzed BMDC from Mda-5−/− and RIG-I−/− mice. In the absence of either receptor, there is a significant decrease in BMDC activation at 12h post infection. However, only RIG-I−/− cells exhibit a delay in type I IFN production. In order to determine the role that IPS-1 plays in vivo, we infected mice with pathogenic RABV. We see that IPS-1−/− mice are more susceptible to infection than IPS-1+/+ mice and have a significantly increased incident of limb paralysis., Author Summary Rabies virus (RABV) is a neurotropic RNA virus responsible for the deaths of the at least 40,000 to 70,000 individuals globally each year. However, the innate immune response induced by both wildtype and vaccine strains of RABV is not well understood. In this study, we assessed the pattern recognition receptors involved in the host immune response to RABV in bone marrow derived dendritic cells (DC). Our studies revealed that Toll like receptor (TLR) signaling is not required to induce innate responses to RABV. On the other hand, we see that IPS-1, the adaptor protein for RIG-I like receptor (RLR) signaling, is essential for induction of innate immune responses. Furthermore, we found that RIG-I and Mda-5, both RLRs, are able to induce DC activation and type I interferon production. This finding is significant as we can target unused pattern recognition receptors with recombinant RABV vaccine strains to elicit a varied, and potentially protective, immune response. Lastly, we show that IPS-1 plays an important role in mediating the pathogenicity of RABV and preventing RABV associated paralysis. Overall, this study illustrates that RLRs are essential for recognition of RABV infection and that the subsequent host cell signaling is required to prevent disease.