The Adjuvant Combination of dmLT and Monophosphoryl Lipid A Activates the Canonical, Nonpyroptotic NLRP3 Inflammasome in Dendritic Cells and Significantly Interacts to Expand Antigen-Specific CD4 T Cells.

Adjuvants are often essential additions to vaccines that enhance the activation of innate immune cells, leading to more potent and protective T and B cell responses. Only a few vaccine adjuvants are currently used in approved vaccine formulations in the United States. Combinations of one or more adjuvants have the potential to increase the efficacy of existing and next-generation vaccines. In this study, we investigated how the nontoxic double mutant Escherichia coli heat-labile toxin R192G/L211A (dmLT), when combined with the TLR4 agonist monophosphoryl lipid A (MPL-A), impacted innate and adaptive immune responses to vaccination in mice. We found that the combination of dmLT and MPL-A induced an expansion of Ag-specific, multifaceted Th1/2/17 CD4 T cells higher than that explained by adding responses to either adjuvant alone. Furthermore, we observed more robust activation of primary mouse bone marrow-derived dendritic cells in the combination adjuvant-treated group via engagement of the canonical NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome complex. This was marked by a multiplicative increase in the secretion of active IL-1ß that was independent of classical gasdermin D-mediated pyroptosis. Moreover, the combination adjuvant increased the production of the secondary messengers cAMP and PGE2 in dendritic cells. These results demonstrate how certain adjuvant combinations could be used to potentiate better vaccine responses to combat a variety of pathogens.

Menopausal hormone therapy and risk of cardiovascular events in women with prediabetes or type 2 diabetes: A pooled analysis of 2917 postmenopausal women.

BACKGROUND AND AIMS: The effect of MHT on cardiovascular disease (CVD) risk among women with prediabetes or type 2 diabetes (PreDM or T2DM) is unclear. We examined the association between ever or early use MHT and CVD risk in postmenopausal women with PreDM or T2DM, and the potential modifying effect of race. METHODS: 2,917 postmenopausal women with PreDM or T2DM were pooled from 3 prospective CVD cohorts (the Atherosclerosis Risk in Communities, the Multi-Ethnic Study of Atherosclerosis, and the Jackson Heart Study). Ever (yes vs no) or early use of MHT (MHT initiated ≤5 vs > 5 years since menopause), and their associations with ischemic stroke, coronary heart disease (CHD), and atherosclerotic cardiovascular disease (ASCVD) were assessed using Cox proportional hazards models. RESULTS: During a median follow-up of 15 years, 264 stroke, 484 CHD, and 659 ASCVD events were observed. In fully adjusted models, ever use of MHT was associated with reduced risk of stroke (hazard ratio 0.86, 95% CI 0.76-0.98), CHD (0.85, 0.74-0.98), and ASCVD (0.83, 0.73-0.95) in white women with PreDM or T2DM. Early use of MHT was associated with reduced risk of stroke (0.82, 0.72-0.95), CHD (0.85, 0.74-0.98), and ASCVD (0.82, 0.70-0.96) in the white group. No risk reduction with ever or early use of MHT was found for black women with PreDM or T2DM. CONCLUSIONS: MHT is associated with statistically reduced CVD risk among white but not black women with PreDM or DM. Race is an effect modifier in the association between MHT use and CVD.

Early Menopause and Cardiovascular Disease Risk in Women With or Without Type 2 Diabetes: A Pooled Analysis of 9,374 Postmenopausal Women.

OBJECTIVE: Early menopause may be associated with higher cardiovascular disease (CVD) risk. Type 2 diabetes mellitus (T2DM), coupled with early menopause, may result in even greater CVD risk in women. We examined CVD risk in women with early compared with normal-age menopause, with and without T2DM overall, and by race/ethnicity. RESEARCH DESIGN AND METHODS: We pooled data from the Atherosclerosis Risk in Communities study, the Multi-Ethnic Study of Atherosclerosis, and the Jackson Heart Study. We included women with data on menopausal status, menopausal age, and T2DM, excluding pre- or perimenopausal women and those with prevalent CVD. Outcomes included incident coronary heart disease (CHD), stroke, heart failure (HF), and atherosclerotic cardiovascular disease (ASCVD) (CHD or stroke). We estimated the risk associated with early (<45 years) compared with normal-age menopause using Cox proportional hazards models. Covariates included age, race/ethnicity, education, BMI, blood pressure, cholesterol, smoking, alcohol consumption, antihypertensive medication, lipid-lowering medication, hormone therapy use, and pregnancy history. RESULTS: We included 9,374 postmenopausal women for a median follow-up of 15 years. We observed 1,068 CHD, 659 stroke, 1,412 HF, and 1,567 ASCVD events. T2DM significantly modified the effect of early menopause on CVD risk. Adjusted hazard ratios for early menopause and the outcomes were greater in women with T2DM versus those without (CHD 1.15 [95% CI 1.00, 1.33] vs. 1.09 [1.03, 1.15]; stroke 1.21 [1.04, 1.40] vs. 1.10 [1.04, 1.16]; ASCVD 1.29 [1.09, 1.51] vs. 1.10 [1.04, 1.17]; HF 1.18 [1.00, 1.39] vs. 1.09 [1.03, 1.16]). The modifying effect of T2DM on the association between early menopause and ASCVD was only statistically significant in Black compared with White women. CONCLUSIONS: Early menopause was associated with an increased risk for CVD in postmenopausal women. T2DM may further augment the risk, particularly in Black women.

IgE-activated mast cells enhance TLR4-mediated antigen-specific CD4+ T cell responses.

Mast cells are potent mediators of allergy and asthma, yet their role in regulating adaptive immunity remains ambiguous. On the surface of mast cells, the crosslinking of IgE bound to FcεRI by a specific antigen recognized by that IgE triggers the release of immune mediators such as histamine and cytokines capable of activating other immune cells; however, little is known about the mast cell contribution to the induction of endogenous, antigen-specific CD4+ T cells. Here we examined the effects of specific mast cell activation in vivo on the initiation of an antigen-specific CD4+ T cell response. While CD4+ T cells were not enhanced by FcεRI stimulation alone, their activation was synergistically enhanced when FcεRI activation was combined with TLR4 stimulation. This enhanced activation was dependent on global TLR4 stimulation but appeared to be less dependent on mast cell expressed TLR4. This study provides important new evidence to support the role of mast cells as mediators of the antigen-specific adaptive immune response.

Novel Risk Factors for Progression of Diabetic and Nondiabetic CKD: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study.

RATIONALE & OBJECTIVE: Identification of novel risk factors for chronic kidney disease (CKD) progression may inform mechanistic investigations and improve identification of high-risk subgroups. The current study aimed to characterize CKD progression across levels of numerous risk factors and identify independent risk factors for CKD progression among those with and without diabetes. STUDY DESIGN: The Chronic Renal Insufficiency Cohort (CRIC) Study is a prospective cohort study of adults with CKD conducted at 7 US clinical centers. SETTING & PARTICIPANTS: Participants (N=3,379) had up to 12.3 years of follow-up; 47% had diabetes. PREDICTORS: 30 risk factors for CKD progression across sociodemographic, behavioral, clinical, and biochemical domains at baseline. OUTCOMES: Study outcomes were estimated glomerular filtration rate (eGFR) slope and the composite of halving of eGFR or initiation of kidney replacement therapy. ANALYTICAL APPROACH: Stepwise selection of independent risk factors was performed stratified by diabetes status using linear mixed-effects and Cox proportional hazards models. RESULTS: Among those without and with diabetes, respectively, mean eGFR slope was-1.4±3.3 and-2.7±4.7mL/min/1.73m2 per year. Among participants with diabetes, multivariable-adjusted hazard of the composite outcome was approximately 2-fold or greater with higher levels of the inflammatory chemokine CXCL12, the cardiac marker N-terminal pro-B-type natriuretic peptide (NT-proBNP), and the kidney injury marker urinary neutrophil gelatinase-associated lipocalin (NGAL). Among those without diabetes, low serum bicarbonate and higher high-sensitivity troponin T, NT-proBNP, and urinary NGAL levels were all significantly associated with a 1.5-fold or greater rate of the composite outcome. LIMITATIONS: The observational study design precludes causal inference. CONCLUSIONS: Strong associations for cardiac markers, plasma CXCL12, and urinary NGAL are comparable to that of systolic blood pressure≥140mm Hg, a well-established risk factor for CKD progression. This warrants further investigation into the potential mechanisms that these markers indicate and opportunities to use them to improve risk stratification.

Unique Transcriptome Changes in Peripheral B Cells Revealed by Comparing Age Groups From Naive or Vaccinated Mice, Including snoRNA and Cdkn2a.

Aging is associated with a decline in immune function that is not fully understood including vaccine failure. Here we report transcriptomic analysis on B cells from naive or influenza-vaccinated mice of 3 ages: young (15-23 weeks), middle-aged (63-81 weeks), and old mice (103-119 weeks). Our goal was expression profiling of B cells by age and history of vaccination to identify novel changes at the transcriptome level. We observed waning vaccine responses with age. In B cell transcripts, age and vaccination history were both important with notable differences observed in conducted analyses (eg, principal component, gene set enrichment, differentially expressed [DE] genes, and canonical pathways). Only 39 genes were significantly DE with age irrespective of vaccine history. This included age-related changes to box C/D small nucleolar (sno) RNAs, Snord123 and Snord1a. Box C/D snoRNAs regulate rRNAs through methylation and are linked to neurodegenerative, inflammatory, and cancer diseases but not specifically B cells or age. Canonical pathway changes implicated with age irrespective of vaccination history included EIF2, mTOR signaling, p53, Paxillin, and Tec kinase signaling pathways as well as cell cycle checkpoint. Importantly, we identified DE genes and pathways that were progressively altered starting in middle-age (eg, signaling by Rho family GTPases) or only altered in middle-age (eg, sphingosine-1-phosphate signaling), despite minimal differences in the ability of these mice to respond to vaccination compared to younger mice. Our results indicate the importance of vaccination or immune stimulation and analyses of multiple age ranges for aging B cell studies and validate an experimental model for future studies.

LTA1 and dmLT enterotoxin-based proteins activate antigen-presenting cells independent of PKA and despite distinct cell entry mechanisms.

Enterotoxin-based proteins are powerful manipulators of mucosal immunity. The A1 domain of heat-labile enterotoxin from E. coli, or LTA1, is a newer adjuvant from this family under investigation for intranasal vaccines. Although LTA1 has been examined in mouse vaccination studies, its ability to directly stimulate immune cells compared to related adjuvant proteins has not been well explored. Here, we perform the first rigorous examination of LTA1's effect on antigen presenting cells (APC) using a human monocyte cell line THP-1. To better understand LTA1's stimulatory effects, we compared it to dmLT, or LT-R192G/L211A, a related AB5 adjuvant in clinical trials for oral or parenteral vaccines. LTA1 and dmLT both activated APCs to upregulate MHC-II (HLA-DR), CD86, cytokine secretion (e.g., IL-1ß) and inflammasome activation. The effect of LTA1 on surface marker changes (e.g., MHC-II) was highly dose-dependent whereas dmLT exhibited high MHC-II expression regardless of dose. In contrast, cytokine secretion profiles were similar and dose-dependent after both LTA1 and dmLT treatment. Cellular activation by LTA1 was independent of ganglioside binding, as pre-treatment with purified GM1 blocked the effect of dmLT but not LTA1. Unexpectedly, while activation of the inflammasome and cytokine secretion by LTA1 or dmLT was blocked by the protein kinase A inhibitor H89 (similar to previous reports), these responses were not inhibited by a more specific PKA peptide inhibitor or antagonist; thus Indicating that a novel and unknown mechanism is responsible for inflammasome activation and cytokine secretion by LT proteins. Lastly, LTA1 stimulated a similar cytokine profile in primary human monocytes as it did in THP1 cells, including IL-1ß, IL-6, IL-8, MIP-1α, MIP-1ß, and TNFα. Thus, we report that LTA1 protein programs a dendritic cell-like phenotype in APCs similar to dmLT in a mechanism that is independent of PKA activation and GM1 binding and entry.

Intradermal or Sublingual Delivery and Heat-Labile Enterotoxin Proteins Shape Immunologic Responses to a CFA/I Fimbria-Derived Subunit Antigen Vaccine against Enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli (ETEC) is a major cause of infectious diarrhea in children, travelers, and deployed military personnel. As such, development of a vaccine would be advantageous for public health. One strategy is to use subunits of colonization factors combined with antigen/adjuvant toxoids as an ETEC vaccine. Here, we investigated the intradermal (i.d.) or sublingual (s.l.) delivery of CFA/I fimbrial antigens, including CfaEB and a CfaE-heat-labile toxin B subunit (LTB) chimera admixed with double mutant heat-labile toxin (LT) LT-R192G/L211A (dmLT). In addition, we compared dmLT with other LT proteins to better understand the generation of adjuvanted fimbrial and toxoid immunity as well as the influence on any local skin reactogenicity. We demonstrate that immunization with dmLT admixed with CfaEB induces robust serum and fecal antibody responses to CFA/I fimbriae and LT but that i.d. formulations are not optimal for s.l. delivery. Improved s.l. vaccination outcomes were observed when higher doses of dmLT (1 to 5 µg) were admixed with CfaEB or, even better, when a CfaE-LTB chimera antigen was used instead. Serum anti-CFA/I total antibodies, detected by enzyme-linked immunosorbent assay, were the best predictor of functional antibodies, based on the inhibition of red blood cell agglutination by ETEC. Immunization with other LT proteins or formulations with altered B-subunit binding during i.d. immunization (e.g., by addition of 5% lactose, LTA1, or LT-G33D) minimally altered the development of antibody responses and cytokine recall responses but reduced skin reactogenicity at the injection site. These results reveal how formulations and delivery parameters shape the adaptive immune responses to a toxoid and fimbria-derived subunit vaccine against ETEC.