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BACKGROUND: Multifood Oral Immunotherapy (mOIT) with adjunctive anti-IgE (omalizumab, Xolair(®)) treatment affords safe, effective, and rapid desensitization to multiple foods, although the specific immune mechanisms mediating this desensitization remain to be fully elucidated. METHODS: Participants in our phase 2 mOIT trial (NCT02643862) received omalizumab from baseline to week 16 and mOIT from week 8 to week 36. We compared the immune profile of PBMCs and plasma taken at baseline, week 8 and week 36 using high-dimensional mass cytometry, component-resolved diagnostics, the indirect basophil activation test, and Luminex. RESULTS: We found (i) decreased frequency of IL4(+) peanut-reactive CD4(+) T cells and a marked downregulation of GPR15 expression and CXCR3 frequency among γδ and CD8(+) T cell subsets at week 8 during the initial, omalizumab-alone induction phase; (ii) significant upregulation of the skin-homing receptor CCR4 in peanut-reactive CD4(+) T and Th2 effector memory (EM) cells and of cutaneous lymphocyte-associated antigen (CLA) in peanut-reactive CD8(+) T and CD8(+) EM cells (iii) downregulation of CD86 expression among antigen-presenting cell subsets; and (iv) reduction in pro-inflammatory cytokines, notably IL-17, at week 36 post-OIT. We also observed significant attenuation of the Th2 phenotype post-OIT, defined by downregulation of IL-4 peanut-reactive T cells and OX40 in Th2EM cells, increased allergen component-specific IgG(4)/IgE ratio, and decreased allergen-driven activation of indirectly sensitized basophils. CONCLUSIONS: This exploratory study provides novel comprehensive insight into the immune underpinnings of desensitization through omalizumab-facilitated mOIT. Moreover, this study provides encouraging results to support the complex immune changes that can be induced by OIT.

To permit the recognition of antigens, T cells generate a vast diversity of T cell receptor (TCR) sequences. Upon binding of the TCR to an antigen–MHC complex, T cells clonally expand to establish an immune response. To study antigen-specific T cell clonality, we have developed a method that allows selection of rare cells, based on RNA expression, before in-depth scRNA-seq (named SELECT-seq). We applied SELECT-seq to collect both TCR sequences and then transcriptomes from single cells of peripheral blood lymphocytes activated by a Mycobacterium tuberculosis ( Mtb ) lysate. TCR sequence analysis allowed us to preferentially select expanded conventional CD8 + T cells as well as invariant natural killer T (iNKT) cells and mucosal-associated invariant T (MAIT) cells. The iNKT and MAIT cells have a highly similar transcriptional pattern, indicating that they carry out similar immunological functions and differ considerably from conventional CD8 + T cells. While there is no relationship between expression profiles and clonal expansion in iNKT or MAIT cells, highly expanded conventional CD8 + T cells down-regulate the interleukin 2 (IL-2) receptor alpha (IL2RA, or CD25) protein and show signs of senescence. This suggests inherent limits to clonal expansion that act to diversify the T cell response repertoire.

Background: Despite advances in medical therapy, heart attack and stroke remain leading causes of morbidity and mortality. Biological, epidemiological, and clinical studies have shown that many patients (up to 33% in some trials) still have residual inflammatory risk that is associated with plaque rupture, even in the setting of low LDL. Methods and Results: In this study, we analyzed the T cell landscape of coronary atherosclerotic plaque to determine their role in the development of atherosclerosis and its adverse sequelae. We recruited 17 patients undergoing heart transplantation. From each explanted heart, we obtained plaques from the major coronary arteries, digested them to form a single cell suspension, sorted the arteries for CD4 and CD8 T cells into 96 well plates, and submitted them for single cell genotyping and phenotyping ( Figure 1 ). Although peripheral blood from these patients also contains T cell clones, plaque CD8 T cell clones appear to function differently than blood (e.g., producing more BCL6, TNF-, and interferon gamma) further supporting that this is not a bystander effect. We found CD4 and CD8 T cells with identical TCR sequence across the arteries of the same patient, suggesting CD8T cells are purposely recruited to the plaques. When we analyzed the percent clonality based upon location and disease severity, we find that clonality is not dependent on location and is present at all severity levels, especially, in early disease (e.g., AHA Type I-IV lesions. Conclusion: CD8 T cells are clonally expanded in atherosclerotic plaque and appear to function differently than blood, suggesting these cells are purposefully recruited.

Most infections with Mycobacterium tuberculosis (Mtb) manifest as a clinically asymptomatic, contained state, known as latent tuberculosis infection, that affects approximately one-quarter of the global population(1). Although fewer than one in ten individuals eventually progress to active disease(2), tuberculosis is a leading cause of death from infectious disease worldwide(3). Despite intense efforts, immune factors that influence the infection outcomes remain poorly defined. Here we used integrated analyses of multiple cohorts to identify stage-specific host responses to Mtb infection. First, using high-dimensional mass cytometry analyses and functional assays of a cohort of South African adolescents, we show that latent tuberculosis is associated with enhanced cytotoxic responses, which are mostly mediated by CD16 (also known as FcγRIIIa) and natural killer cells, and continuous inflammation coupled with immune deviations in both T and B cell compartments. Next, using cell-type deconvolution of transcriptomic data from several cohorts of different ages, genetic backgrounds, geographical locations and infection stages, we show that although deviations in peripheral B and T cell compartments generally start at latency, they are heterogeneous across cohorts. However, an increase in the abundance of circulating natural killer cells in tuberculosis latency, with a corresponding decrease during active disease and a return to baseline levels upon clinical cure are features that are common to all cohorts. Furthermore, by analysing three longitudinal cohorts, we find that changes in peripheral levels of natural killer cells can inform disease progression and treatment responses, and inversely correlate with the inflammatory state of the lungs of patients with active tuberculosis. Together, our findings offer crucial insights into the underlying pathophysiology of tuberculosis latency, and identify factors that may influence infection outcomes.

The development of vaccines is considered a key milestone in preventive medicine. There is no comparable cost-effective means for controlling or eradicating infectious diseases. Yet, a persistent societal problem is the concern about vaccine's safety and long-term effects, and this caters to detractors of vaccination. Pathogen-derived antigen(s) as well as adjuvants/immunostimulants are essential for vaccine efficacy. Currently, adjuvant selection is largely empirical, but the mechanism underlying adjuvanticity is beginning to unravel. This should help develop more defined or targeted adjuvants.This review provides a brief account and analysis of the host immune parameters modulated by some commonly used as well as new adjuvants, including phytol-based diterpenoids. The major efforts are directed toward evaluating their relative safety and immunomodulatory efficiency, compared to known synthetic and natural adjuvants. Concerns for adverse pathological inflammation and autoimmunity are also addressed.The phytol-based adjuvants hold great promise for improving vaccine efficacy, as they cause little or no persistent inflammation, but are highly effective in stimulating a multifaceted immune response, characterized by proficient recruitment of immune cells, generation of antibody and immunological memory, and activation of both Th1 and Th2 responses. Future focus will be on developing cocktail adjuvants to activate the complement system, mobilize follicular T helper cells as well as NKT and γδ T cells and activate cross-presenting dendritic cells to stimulate CD8(+) effector T cells.

The ubiquitous gram-positive bacterium Staphylococcus aureus occupies a unique niche in humans for its ability to survive both as a commensal and a life-threatening pathogen. Its complex relationship with the host and its ability to engender a throng of virulence factors, have hindered the development of a successful vaccine against it. The use of immunoadjuvants to enhance host immunity and prevent the shift from commensalism to pathogenicity is a rational approach for containing infection. The objective of this study was to understand the mechanisms by which alum and two phytol-derived immunoadjuvants, phytanol (PHIS-01) 1 and phytanyl chloride (PCl) 2 shape the interaction between S. aureus and its murine host. We studied the effects of the phytol derivatives, relative to alum, on the induction of inflammatory cytokines and chemokines, recruitment of CD11b+ cells, generation of specific anti-S. aureus antibodies and in vitro clearance of S. aureus. Our results showed that both PHIS-01 and PCl were stronger inducers of protective cytokines IL-17 and IL-1β than alum, and far exceeded alum in enhancing anti-S. aureus antibody response. However, both alum and the phytol derivatives (particularly PCl) promoted efficient recruitment of CD11b+ cells. Furthermore, PHIS-01, alum and to a lesser extent, PCl were able to up-regulate the expression of key inflammation-related genes that were highly down-regulated by S. aureus alone. In vitro killing assays showed that both PHIS-01 and PCl were far more potent than alum in promoting S. aureus clearance; this indicated their efficiency in shaping an effective anti-S. aureus immune microenvironment. In summary, our study provides evidence for the better effectiveness of phytol-derived immunoadjuvants over alum in enhancing anti-S. aureus immunity.

This review describes the adjuvanticity of novel diterpenoids (synthetic phytol derivatives) compared to some commercially available adjuvants. The efficacy of the phytol-derived immunostimulants was evaluated in terms of their ability to activate innate immunity, amplify various antigen-specific immune responses, and engender immunological memory with no discernible adverse effects in both competent and immune-deficient mice. The profile that emerges out of these studies reveals that the phytol derivatives are excellent immunostimulants, superior to a number of commercial adjuvants in terms of long-term memory induction and activation of both innate and acquired immunity. Additionally, the phytol-derived compounds have no cumulative inflammatory or toxic effects even in immuno-compromised mice.

In a previous report, we observed that the phytol-derived immunostimulant, PHIS-01 (phytanol), is a nontoxic oil-in-water adjuvant which is superior to most commercial adjuvants. In contrast, the parent diterpene alcohol phytol, though highly effective as an adjuvant, is relatively toxic. To assess the importance of the polar functional group in PHIS-01, we prepared two new compounds PHIS-02 (phytanyl amine) and PHIS-03 (phytanyl mannose). All three phytol derivatives proved to be excellent adjuvants, but differed in solubility and mode of action. To delineate their molecular signatures in the local microenvironment, we performed inflammasome and cytokine microarray analyses with the peritoneal fluid of mice treated with alum or the phytol compounds above, in the presence or absence of soluble protein antigens. We report here that the phytol derivatives had a significant time-dependent impact on the host chemokine-cytokine microenvironment and subsequently on specific humoral responses. Moreover, the inclusion of protein immunogens induced further changes in host microenvironments, including rapid (2h) expression of cytokines and chemotactic factors (IL-6, MCP-1, KC, MIP-1, and LIX), implying mobilization and activation of neutrophils, and monocytes. PHIS-01 proved to be the most effective in this regard. Inflammatory cytokine cascades were dominant even after 24h possibly to facilitate involvement of the acquired immune system with the release of B-lymphocyte chemo-attractant BLC, T-cell activation-3 chemokines TCA, IL-4, IL-12, and TIMP-1. We also noted enhanced expression of NLRP genes including NLRP3 with both alum and phytol derivatives (particularly PHIS-01).