Human memory T cells with a naive phenotype accumulate with aging and respond to persistent viruses.

The number of naive T cells decreases and susceptibility to new microbial infections increases with age. Here we describe a previously unknown subset of phenotypically naive human CD8(+) T cells that rapidly secreted multiple cytokines in response to persistent viral antigens but differed transcriptionally from memory and effector T cells. The frequency of these CD8(+) T cells, called 'memory T cells with a naive phenotype' (TMNP cells), increased with age and after severe acute infection and inversely correlated with the residual capacity of the immune system to respond to new infections with age. CD8(+) TMNP cells represent a potential new target for the immunotherapy of persistent infections and should be accounted for and subtracted from the naive pool if truly naive T cells are needed to respond to antigens.

Pre-vaccination frequency of circulatory Tfh is associated with robust immune response to TV003 dengue vaccine.

It has been estimated that more than 390 million people are infected with Dengue virus every year; around 96 millions of these infections result in clinical pathologies. To date, there is only one licensed viral vector-based Dengue virus vaccine CYD-TDV approved for use in dengue endemic areas. While initially approved for administration independent of serostatus, the current guidance only recommends the use of this vaccine for seropositive individuals. Therefore, there is a critical need for investigating the influence of Dengue virus serostatus and immunological mechanisms that influence vaccine outcome. Here, we provide comprehensive evaluation of sero-status and host immune factors that correlate with robust immune responses to a Dengue virus vector based tetravalent vaccine (TV003) in a Phase II clinical cohort of human participants. We observed that sero-positive individuals demonstrate a much stronger immune response to the TV003 vaccine. Our multi-layered immune profiling revealed that sero-positive subjects have increased baseline/pre-vaccination frequencies of circulating T follicular helper (cTfh) cells and the Tfh related chemokine CXCL13/BLC. Importantly, this baseline/pre-vaccination cTfh profile correlated with the vaccinees' ability to launch neutralizing antibody response against all four sero-types of Dengue virus, an important endpoint for Dengue vaccine clinical trials. Overall, we provide novel insights into the favorable cTfh related immune status that persists in Dengue virus sero-positive individuals that correlate with their ability to mount robust vaccine specific immune responses. Such detailed interrogation of cTfh cell biology in the context of clinical vaccinology will help uncover mechanisms and targets for favorable immuno-modulatory agents.

Improved Durability to SARS-CoV-2 Vaccine Immunity following Coimmunization with Molecular Adjuvant Adenosine Deaminase-1.

Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have demonstrated strong immunogenicity and protection against severe disease, concerns about the duration and breadth of these responses remain. In this study, we show that codelivery of plasmid-encoded adenosine deaminase-1 (pADA) with SARS-CoV-2 spike glycoprotein DNA enhances immune memory and durability in vivo. Coimmunized mice displayed increased spike-specific IgG of higher affinity and neutralizing capacity as compared with plasmid-encoded spike-only-immunized animals. Importantly, pADA significantly improved the longevity of these enhanced responses in vivo. This coincided with durable increases in frequencies of plasmablasts, receptor-binding domain-specific memory B cells, and SARS-CoV-2-specific T follicular helper cells. Increased spike-specific T cell polyfunctionality was also observed. Notably, animals coimmunized with pADA had significantly reduced viral loads compared with their nonadjuvanted counterparts in a SARS-CoV-2 infection model. These data suggest that pADA enhances immune memory and durability and supports further translational studies.

Outcomes of Percutaneous Revascularization in Severe Ischemic Left Ventricular Dysfunction.

PURPOSE OF REVIEW: This article presents a comprehensive review of coronary revascularization versus optimal medical therapy (OMT) in patients with severe ischemic left ventricular dysfunction. RECENT FINDINGS: The REVIVED-BCIS2 trial randomized 700 patients with extensive coronary artery disease and left ventricular (LV) ejection fraction (LVEF) ≤ 35% and viability in more than four dysfunctional myocardial segments to percutaneous coronary intervention (PCI) plus OMT versus OMT alone. Over a median duration of 41 months, there was no difference in the composite of all-cause mortality, heart failure hospitalization, or improvement in LVEF with PCI plus OMT versus OMT alone at 6 and 12 months, quality of life scores at 24 months, or fatal ventricular arrhythmia. The STICH randomized trial was conducted between 2002 and 2007, involving patients with LV dysfunction and coronary artery disease. The patients were assigned to either CABG plus medical therapy or medical therapy alone. At the 5-year follow-up, the trial showed that CABG plus medical therapy reduced cardiovascular disease-related deaths and hospitalizations but no reduction in all-cause mortality. However, a 10-year follow-up showed a significant decrease in all-cause mortality with CABG. The currently available evidence showed no apparent benefit of PCI in severe ischemic cardiomyopathy as compared to OMT, but that CABG improves outcomes in this patient population. The paucity of data on the advantages of PCI in this patient population underscores the critical need for optimization of medical therapy for better survival and quality of life until further evidence from RCTs is available.

Germinal Center T follicular helper (GC-Tfh) cell impairment in chronic HIV infection involves c-Maf signaling.

We have recently demonstrated that the function of T follicular helper (Tfh) cells from lymph nodes (LN) of HIV-infected individuals is impaired. We found that these cells were unable to provide proper help to germinal center (GC)-B cells, as observed by altered and inefficient anti-HIV antibody response and premature death of memory B cells. The underlying molecular mechanisms of this dysfunction remain poorly defined. Herein, we have used a unique transcriptional approach to identify these molecular defects. We consequently determined the transcriptional profiles of LN GC-Tfh cells following their interactions with LN GC-B cells from HIV-infected and HIV-uninfected individuals, rather than analyzing resting ex-vivo GC-Tfh cells. We observed that proliferating GC-Tfh cells from HIV-infected subjects were transcriptionally different than their HIV-uninfected counterparts, and displayed a significant downregulation of immune- and GC-Tfh-associated pathways and genes. Our results strongly demonstrated that MAF (coding for the transcription factor c-Maf) and its upstream signaling pathway mediators (IL6R and STAT3) were significantly downregulated in HIV-infected subjects, which could contribute to the impaired GC-Tfh and GC-B cell functions reported during infection. We further showed that c-Maf function was associated with the adenosine pathway and that the signaling upstream c-Maf could be partially restored by adenosine deaminase -1 (ADA-1) supplementation. Overall, we identified a novel mechanism that contributes to GC-Tfh cell impairment during HIV infection. Understanding how GC-Tfh cell function is altered in HIV is crucial and could provide critical information about the mechanisms leading to the development and maintenance of effective anti-HIV antibodies.

Same day discharge versus overnight observation following chronic total occlusion percutaneous coronary intervention: Insights from the PROGRESS-CTO registry.

BACKGROUND: Same day discharge (SDD) following chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study. METHODS: We evaluated the clinical, angiographic, and procedural characteristics of patients discharged the same day versus those kept for overnight observation in the Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (PROGRESS-CTO, NCT02061436). RESULTS: Of the 7181 patients who underwent CTO PCI, 943 (13%) had SDD. The SDD rate increased from 3% in 2015 to 21% in 2022. Patients with SDD were less likely to have a history of heart failure (21% vs. 26%, p = 0.005), chronic lung disease (10% vs. 15%, p = 0.001), or anemia (12% vs. 19%, p < 0.001). Technical success (87% vs. 88%, p = 0.289) was similar, but in-hospital major adverse cardiovascular events (0.0% vs. 0.4%, p = 0.041) were lower in SDD. In multivariable logistic regression analysis, prior myocardial infarction odds ratio (OR): 0.71 (95% confidence interval [CI]: 0.59-0.87, p = 0.001), chronic lung disease OR: 0.64 (95% CI: 0.47-0.88, p = 0.006), and increasing procedure time OR: 0.93 (95% CI: 0.91-0.95, p < 0.001, per 10-min increase) were associated with overnight observation, while radial-only access OR: 2.45 (95% CI: 2.03-2.96, p < 0.001) had the strongest association with SDD. In the SDD, 2 (0.4%) of 514 patients were readmitted, due to retroperitoneal bleeding (n = 1) and ischemic stroke (n = 1). CONCLUSION: The overall frequency of SDD after CTO PCI was 13% and has been increasing over time. SDD is feasible in select patients following CTO PCI, and radial-only access had the strongest association with SDD.

Human circulating PD-1+CXCR3-CXCR5+ memory Tfh cells are highly functional and correlate with broadly neutralizing HIV antibody responses.

The vast majority of currently licensed human vaccines work on the basis of long-term protective antibody responses. It is now conceivable that an antibody-dependent HIV vaccine might be possible, given the discovery of HIV broadly neutralizing antibodies (bnAbs) in some HIV-infected individuals. However, these antibodies are difficult to develop and have characteristics indicative of a high degree of affinity maturation in germinal centers (GCs). CD4⁺ T follicular helper (Tfh) cells are specialized for B cell help and necessary for GCs. Therefore, the development of HIV bnAbs might depend on Tfh cells. Here, we identified in normal individuals a subpopulation of circulating memory PD-1⁺CXCR5⁺CD4⁺ T cells that are resting memory cells most related to bona fide GC Tfh cells by gene expression profile, cytokine profile, and functional properties. Importantly, the frequency of these cells correlated with the development of bnAbs against HIV in a large cohort of HIV⁺ individuals.

Radial access for chronic total occlusion percutaneous coronary intervention: Insights from the PROGRESS-CTO registry.

Use of radial access for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has been increasing. We examined the clinical characteristics and procedural outcomes of patients who underwent CTO PCI with radial versus femoral access in the Prospective Global Registry for the Study of CTO Intervention (PROGRESS-CTO, NCT02061436). Of 10,954 patients who underwent CTO PCI at 55 centers in 7 countries between 2012 and 2022, 2578 (24%) had a radial only approach. Patients who underwent radial only access were younger (63 ± 10 vs. 65 ± 10, years, p &lt; 0.001), more likely to be men (84% vs. 81%, p = 0.001), and had significantly lower prevalence of comorbidities compared with the femoral access group including diabetes mellitus (39% vs. 45%, p &lt; 0.001) and coronary artery bypass graft surgery (57% vs. 64%, p &lt; 0.001). In addition, radial only cases had lower angiographic complexity with lower J-CTO and PROGRESS-CTO scores. After adjusting for potential confounders, radial only access was associated with lower risk of access site complications (odds ratio [OR]: 0.45, 95% confidence interval [CI]: 0.22-0.91), similar technical success (OR: 0.87, 95% CI: 0.74-1.04) and major adverse cardiovascular events (MACE) (OR: 0.65, 95% CI: 0.40-1.07), compared with the femoral access group. Radial only access was used in 24% of CTO PCIs and was associated with lower access site complications, and similar technical success and MACE as compared with the femoral access group.

Antegrade dissection and re-entry versus parallel wiring in chronic total occlusion percutaneous coronary intervention: Insights from the PROGRESS-CTO registry.

BACKGROUND: The comparative efficacy and safety of parallel wiring versus antegrade dissection and re-entry (ADR) in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is controversial. METHODS: We compared the clinical and angiographic characteristics and outcomes of parallel wiring versus ADR after failed antegrade wiring in a large, multicenter CTO PCI registry. RESULTS: A total of 1725 CTO PCI procedures with failed antegrade wiring with a single wire were approached with parallel wiring (692) or ADR (1033) at the discretion of the operator. ADR patients were older (65 ± 10 vs. 62 ± 10, years, p < 0.001) and had higher prevalence of comorbidities, such as diabetes mellitus (43% vs. 32%, p < 0.001), prior coronary artery bypass graft surgery (31% vs. 19%, p < 0.001), and lower left ventricular ejection fraction (50 ± 14 vs. 53 ± 11%, p < 0.001). The ADR group had higher J-CTO (2.8 ± 1.1 vs. 2.1 ± 1.3, p < 0.001) and PROGRESS-CTO (1.6 ± 1.1 vs. 1.2 ± 1.0, p < 0.001) scores. Equipment use including guidewires, balloons, and microcatheters was higher, and the procedures lasted longer in the ADR group. Technical success (78% vs. 75%, p = 0.046) and major adverse cardiovascular events (composite of all-cause mortality, stroke, acute myocardial infarction, emergency surgery or re-PCI, and pericardiocentesis) (3.7% vs. 1.9%, p = 0.029) were higher in the ADR group, with similar procedural success (75% vs. 73%, p = 0.166). CONCLUSION: In lesions that could not be crossed with antegrade wiring, ADR was associated with higher technical but not procedural success, and also higher MACE compared with parallel wiring.

Predictors of success in primary retrograde strategy in chronic total occlusion percutaneous coronary intervention: insights from the PROGRESS-chronic total occlusion registry.

BACKGROUND: An upfront (primary) retrograde strategy is often used in complex chronic total occlusion (CTO) percutaneous coronary intervention (PCI). METHODS: We examined the clinical, angiographic characteristics, and procedural outcomes of CTO PCIs that were approached with a primary retrograde strategy in the Prospective Global Registry for the Study of CTO Intervention (PROGRESS-CTO, NCT02061436). RESULTS: Of 10,286 CTO PCIs performed between 2012 and 2022, a primary retrograde strategy was used in 1329 (13%) with an initial technical success of 66%, and a final success of 83%. Patients who underwent successful versus unsuccessful primary retrograde cases had similar characteristics: age (65 ± 10 vs. 65 ± 9, years, p = 0.203), men (83% vs. 87%, p = 0.066), prior PCI (71% vs. 71%, p = 0.809), and prior coronary artery bypass graft surgery (52% vs. 53%, p = 0.682). The PROGRESS-CTO score (1.3 ± 0.9 vs. 1.6 ± 0.9, p < 0.001), air kerma radiation (3.9 ± 2.8 vs. 3.4 ± 2.6, gray, p = 0.013), and contrast use (294 ± 148 ml vs. 248 ± 128, ml, p < 0.001) were higher in the unsuccessful group, whereas the presence of interventional collaterals (95% vs. 72%, p < 0.001) and Werner collateral connection grade 2 (43% vs. 31%, p < 0.001) were higher in the successful group. On multivariable logistic regression analysis, the only variable associated with a successful primary retrograde strategy was the presence of interventional collaterals: odds ratio: 6.52 (95% confidence intervals; 3.5-12.1, p < 0.001). CONCLUSION: Presence of interventional collaterals is independently associated with higher success rates with a primary retrograde strategy in CTO PCI.

Intravascular lithotripsy in chronic total occlusion percutaneous coronary intervention: Insights from the PROGRESS-CTO registry.

BACKGROUND: The use of intravascular lithotripsy (IVL) in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study. METHODS: We analyzed the baseline clinical and angiographic characteristics and procedural outcomes of 82 CTO PCIs that required IVL at 14 centers between 2020 and 2022. RESULTS: During the study period, IVL was used in 82 of 3301 (2.5%) CTO PCI procedures (0.4% in 2020 and 7% in 2022; p for trend < 0.001). Mean patient age was 69 ± 11 years and 79% were men. The prevalence of hypertension (95%), diabetes mellitus (62%), and prior PCI (61%) was high. The most common target vessel was the right coronary artery (54%), followed by the left circumflex (23%). The mean J-CTO and PROGRESS-CTO scores were 2.8 ± 1.1 and 1.3 ± 1.0, respectively. Antegrade wiring was the final successful crossing strategy in 65% and the retrograde approach was used in 22%. IVL was used in 10% of all heavily calcified lesions and 11% of all balloon undilatable lesions. The 3.5 mm lithotripsy balloon was the most commonly used balloon (28%). The mean number of pulses per lithotripsy run was 33 ± 32 and the median duration of lithotripsy was 80  (interquartile range: 40-103) seconds. Technical and procedural success was achieved in 77 (94%) and 74 (90%) cases, respectively. Two (2.4%) Ellis Class 2 perforations occurred after IVL use and were managed conservatively. CONCLUSION: IVL is increasingly being used in CTO PCI with encouraging outcomes.

Is There a Role for Triple Therapy After ACS?

PURPOSE OF REVIEW: The optimal antithrombotic strategy in patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI) remains the subject of controversy. In this article, we review the current evidence for the use of triple therapy in acute coronary syndrome (ACS) patients. RECENT FINDINGS: The recently published trials of AF patients undergoing PCI have shown that combination of non-vitamin K oral anticoagulants (NOACs) with an antiplatelet agent is either superior or non-inferior to vitamin K antagonist (VKA) plus dual antiplatelet therapy (DAPT) in reducing bleeding complications with no difference in regard to thromboembolic events. Currently, the use of dual therapy (preferably with a NOAC and clopidogrel) is recommended over triple therapy in these patients. The optimal duration should be guided by the assessment of an individual's risk of thrombosis and bleeding events.

Simian-Human Immunodeficiency Virus SHIV.CH505 Infection of Rhesus Macaques Results in Persistent Viral Replication and Induces Intestinal Immunopathology.

Simian-human immunodeficiency viruses (SHIVs) have been utilized to test vaccine efficacy and characterize mechanisms of viral transmission and pathogenesis. However, the majority of SHIVs currently available have significant limitations in that they were developed using sequences from chronically HIV-infected individuals or uncommon HIV subtypes or were optimized for the macaque model by serially passaging the engineered virus in vitro or in vivo Recently, a newly developed SHIV, SHIV.C.CH505.375H.dCT (SHIV.CH505), which incorporates vpu-env (gp140) sequences from a transmitted/founder HIV-1 subtype C strain, was shown to retain attributes of primary HIV-1 strains. However, a comprehensive analysis of the immunopathology that results from infection with this virus, especially in critical tissue compartments like the intestinal mucosa, has not been completed. In this study, we evaluated the viral dynamics and immunopathology of SHIV.CH505 in rhesus macaques. In line with previous findings, we found that SHIV.CH505 is capable of infecting and replicating efficiently in rhesus macaques, resulting in peripheral viral kinetics similar to that seen in pathogenic SIV and HIV infection. Furthermore, we observed significant and persistent depletions of CCR5+ and CCR6+ CD4+ T cells in mucosal tissues, decreases in CD4+ T cells producing Th17 cell-associated cytokines, CD8+ T cell dysfunction, and alterations of B cell and innate immune cell function, indicating that SHIV.CH505 elicits intestinal immunopathology typical of SIV/HIV infection. These findings suggest that SHIV.CH505 recapitulates the early viral replication dynamics and immunopathogenesis of HIV-1 infection of humans and thus can serve as a new model for HIV-1 pathogenesis, treatment, and prevention research.IMPORTANCE The development of chimeric SHIVs has been instrumental in advancing our understanding of HIV-host interactions and allowing for in vivo testing of novel treatments. However, many of the currently available SHIVs have distinct drawbacks and are unable to fully reflect the features characteristic of primary SIV and HIV strains. Here, we utilize rhesus macaques to define the immunopathogenesis of the recently developed SHIV.CH505, which was designed without many of the limitations of previous SHIVs. We observed that infection with SHIV.CH505 leads to peripheral viral kinetics and mucosal immunopathogenesis comparable with those caused by pathogenic SIV and HIV. Overall, these data provide evidence of the value of SHIV.CH505 as an effective model of SIV/HIV infection and an important tool that can be used in future studies, including preclinical testing of new therapies or prevention strategies.

Human Monocyte Subsets Are Transcriptionally and Functionally Altered in Aging in Response to Pattern Recognition Receptor Agonists.

Age-related alterations in immunity have been linked to increased incidence of infections and decreased responses to vaccines in the aging population. Human peripheral blood monocytes are known to promote Ag presentation and antiviral activities; however, the impact of aging on monocyte functions remains an open question. We present an in-depth global analysis examining the impact of aging on classical (CD14+CD16-), intermediate (CD14+CD16+), and nonclassical (CD14dimCD16+) monocytes. Monocytes sorted from nonfrail healthy adults (21-40 y) and old (≥65 y) individuals were analyzed after stimulation with TLR4, TLR7/8, and retinoic acid-inducible gene I agonists. Our data showed that under nonstimulated conditions, monocyte subsets did not reveal significant age-related alternations; however, agonist stimulated-monocytes from adults and old subjects did show differences at the transcriptional and functional levels. These alternations in many immune-related transcripts and biological processes resulted in reduced production of IFN-α, IFN-γ, IL-1ß, CCL20, and CCL8, and higher expression of CX3CR1 in monocytes from old subjects. Our findings represent a comprehensive analysis of the influence of human aging on pattern recognition receptors signaling and monocyte functions, and have implications for strategies to enhance the immune response in the context of infection and immunization.

A Numerically Subdominant CD8 T Cell Response to Matrix Protein of Respiratory Syncytial Virus Controls Infection with Limited Immunopathology.

CD8 T cells are involved in pathogen clearance and infection-induced pathology in respiratory syncytial virus (RSV) infection. Studying bulk responses masks the contribution of individual CD8 T cell subsets to protective immunity and immunopathology. In particular, the roles of subdominant responses that are potentially beneficial to the host are rarely appreciated when the focus is on magnitude instead of quality of response. Here, by evaluating CD8 T cell responses in CB6F1 hybrid mice, in which multiple epitopes are recognized, we found that a numerically subdominant CD8 T cell response against DbM187 epitope of the virus matrix protein expressed high avidity TCR and enhanced signaling pathways associated with CD8 T cell effector functions. Each DbM187 T effector cell lysed more infected targets on a per cell basis than the numerically dominant KdM282 T cells, and controlled virus replication more efficiently with less pulmonary inflammation and illness than the previously well-characterized KdM282 T cell response. Our data suggest that the clinical outcome of viral infections is determined by the integrated functional properties of a variety of responding CD8 T cells, and that the highest magnitude response may not necessarily be the best in terms of benefit to the host. Understanding how to induce highly efficient and functional T cells would inform strategies for designing vaccines intended to provide T cell-mediated immunity.

Altered Memory Circulating T Follicular Helper-B Cell Interaction in Early Acute HIV Infection.

The RV254 cohort of HIV-infected very early acute (4thG stage 1 and 2) (stage 1/2) and late acute (4thG stage 3) (stage 3) individuals was used to study T helper- B cell responses in acute HIV infection and the impact of early antiretroviral treatment (ART) on T and B cell function. To investigate this, the function of circulating T follicular helper cells (cTfh) from this cohort was examined, and cTfh and memory B cell populations were phenotyped. Impaired cTfh cell function was observed in individuals treated in stage 3 when compared to stage 1/2. The cTfh/B cell cocultures showed lower B cell survival and IgG secretion at stage 3 compared to stage 1/2. This coincided with lower IL-10 and increased RANTES and TNF-α suggesting a role for inflammation in altering cTfh and B cell responses. Elevated plasma viral load in stage 3 was found to correlate with decreased cTfh-mediated B cell IgG production indicating a role for increased viremia in cTfh impairment and dysfunctional humoral response. Phenotypic perturbations were also evident in the mature B cell compartment, most notably a decrease in resting memory B cells in stage 3 compared to stage 1/2, coinciding with higher viremia. Our coculture assay also suggested that intrinsic memory B cell defects could contribute to the impaired response despite at a lower level. Overall, cTfh-mediated B cell responses are significantly altered in stage 3 compared to stage 1/2, coinciding with increased inflammation and a reduction in memory B cells. These data suggest that early ART for acutely HIV infected individuals could prevent immune dysregulation while preserving cTfh function and B cell memory.

Fortuitous administration of denosumab in breast carcinoma with osteoclastic giant cells.

Breast carcinoma with osteoclastic giant cells (OGCs) is a rare entity characterized by an admixture of giant cells and malignant epithelial cells within an inflammatory and vascular stroma. Denosumab is a monoclonal antibody that targets the pathway for osteoclast formation and activation, indicated for the prevention of skeletal-related events in patients with bone metastases, as well as for the treatment of giant cell tumor of bone. We report a patient who presented with aggressive bone recurrence of breast cancer 12 years after her original diagnosis, showing a transformed histology that included multinucleated OGCs, and that was refractory to traditional therapy. Misdiagnosed with a tumor-to-tumor metastasis of breast cancer to a giant cell tumor of bone, she was treated with denosumab for her presumed primary bone disease and had a remarkable clinical and radiological response. To the best of our knowledge, this is the first report of breast cancer with OGCs occurring initially in a metastasis while absent in the original tumor and the first description of its successful treatment with denosumab. This case sheds light on the development of giant cells in the tumor microenvironment and suggests the potential use of denosumab in the management of cancers with giant cell elements.

Enhancement of Microbiota in Healthy Macaques Results in Beneficial Modulation of Mucosal and Systemic Immune Function.

Given the critical role of mucosal surfaces in susceptibility to infection, it is imperative that effective mucosal responses are induced when developing efficacious vaccines and prevention strategies for infection. Modulating the microbiota in the gastrointestinal (GI) tract through the use of probiotics (PBio) is a safe and well-tolerated approach to enhance mucosal and overall health. We assessed the longitudinal impact of daily treatment with the VSL#3 probiotic on cellular and humoral immunity and inflammation in healthy macaques. PBio therapy resulted in significantly increased frequencies of B cells expressing IgA in the colon and lymph node (LN), likely because of significantly increased LN T follicular helper cell frequencies and LN follicles. Increased frequencies of IL-23(+) APCs in the colon were found post-PBio treatment, which correlated with LN T follicular helper cells. Finally, VSL#3 significantly downmodulated the response of TLR2-, TLR3-, TLR4-, and TLR9-expressing HEK293 cells to stimulation with Pam3CSK4, polyinosinic-polycytidylic acid, LPS, and ODN2006, respectively. These data provide a mechanism for the beneficial impact of PBio on mucosal health and implicates the use of PBio therapy in the context of vaccination or preventative approaches to enhance protection from mucosal infection by improving immune defenses at the mucosal portal of entry.

Age-Dependent Cell Trafficking Defects in Draining Lymph Nodes Impair Adaptive Immunity and Control of West Nile Virus Infection.

Impaired immune responses in the elderly lead to reduced vaccine efficacy and increased susceptibility to viral infections. Although several groups have documented age-dependent defects in adaptive immune priming, the deficits that occur prior to antigen encounter remain largely unexplored. Herein, we identify novel mechanisms for compromised adaptive immunity that occurs with aging in the context of infection with West Nile virus (WNV), an encephalitic flavivirus that preferentially causes disease in the elderly. An impaired IgM and IgG response and enhanced vulnerability to WNV infection during aging was linked to delayed germinal center formation in the draining lymph node (DLN). Adoptive transfer studies and two-photon intravital microscopy revealed a decreased trafficking capacity of donor naïve CD4+ T cells from old mice, which manifested as impaired T cell diapedesis at high endothelial venules and reduced cell motility within DLN prior to antigen encounter. Furthermore, leukocyte accumulation in the DLN within the first few days of WNV infection or antigen-adjuvant administration was diminished more generally in old mice and associated with a second aging-related defect in local cytokine and chemokine production. Thus, age-dependent cell-intrinsic and environmental defects in the DLN result in delayed immune cell recruitment and antigen recognition. These deficits compromise priming of early adaptive immune responses and likely contribute to the susceptibility of old animals to acute WNV infection.

Direct type I IFN but not MDA5/TLR3 activation of dendritic cells is required for maturation and metabolic shift to glycolysis after poly IC stimulation.

Type I interferons (IFNs) play an important role in direct antiviral defense as well as linking the innate and adaptive immune responses. On dendritic cells (DCs), IFNs facilitate their activation and contribute to CD8(+) and CD4(+) T cell priming. However, the precise molecular mechanism by which IFNs regulate maturation and immunogenicity of DCs in vivo has not been studied in depth. Here we show that, after in vivo stimulation with the TLR ligand poly IC, IFNs dominate transcriptional changes in DCs. In contrast to direct TLR3/mda5 signaling, IFNs are required for upregulation of all pathways associated with DC immunogenicity. In addition, metabolic pathways, particularly the switch from oxidative phosphorylation to glycolysis, are also regulated by IFNs and required for DC maturation. These data provide evidence for a metabolic reprogramming concomitant with DC maturation and offer a novel mechanism by which IFNs modulate DC maturation.