Biology subjects

Dowling, D. J.

Publications and source records attributed to Dowling, D. J..

9 recordsLinked to original sources

bioRxiv2026

Deep phenomics of human PBMCs using a 31-marker spectral flow cytometry panel

Functional cytokines orchestrate leukocyte-mediated innate and adaptive immune responses within the host following infection or immunization. In contrast, lymphocyte-mediated activation-induced markers (AIMs) are predominantly associated with adaptive immune responses. Regulatory T cells (Tregs) primarily function to balance the immune response by preventing excessive inflammation and maintaining self-tolerance. Currently, conventional intracellular cytokine tracking or cytokine-independent AIMs methodology is available for studying antigen-specific lymphocyte or T cell responses in humans. However, this approach faces challenges due to the difficulty in simultaneously deep immunophenotyping the key functional cytokine signatures, AIMs, and nuclear signature of FoxP3+ Tregs. Using spectral flow cytometry, we developed a 31-parameter panel to profile simultaneously major immune cell subsets (B cells, NK cells, DCs, monocytes) along with T cells, memory phenotypes, functional cytokines by tracking established Th1 markers IFN{gamma}, TNF and IL-2; Th2 markers IL-4/5/13 and the Th17 marker, IL-17, AIMs and FoxP3+ Tregs in human PBMCs in steady state as well as in mitogen stimulated conditions. For AIMs, CD69, CD134 (OX40) and CD137 (4-1BB) are included and validated. We also re-validated our panel to profile antigen specific Th1/2/17 cells or AIMs distribution after peptide stimulation. This optimized multicolor spectral flow panel allows a detailed immune profiling of functional cytokines, AIMs and FoxP3+ Tregs in the T cell compartment from human and might be useful for exploratory analysis of how these functional cytokines or AIMs or Tregs shape host immunity after infection or vaccination. Our panel is highly customizable, allowing researchers to tailor it to their specific requirements.

immunology↗

bioRxiv2025

Deep Phenomics of Pattern Recognition Receptor Agonist Specific Activation of Human Blood

Human whole blood (WB) immunophenotyping may represent the in vivo immunological state with better fidelity than artificially isolated peripheral blood mononuclear cells (PBMCs). We used a deep phenomics modeling approach to elucidate the quantitative differences in major immune cell lineages in WB and PBMC compartments in a steady-state in vitro setting. We studied functional innate immune responses induced by pattern recognition receptor agonist adjuvants (PRRa). Using an optimized 49-parameter CyTOF panel and implementing machine learning (ML) algorithms, we mapped PRRa-mediated CD69, CD40, CD80, CD86 and CCR7 activation at the nodal innate immune subsets level. We also portrayed cellular origin of innate functional chemokine CCL4 and intracellular cytokine IFN{gamma} production. We mapped neutrophils as the primary source of TLR7/8 agonist (TLR7/8a) and STING agonist mediated CCL4 responses in WB. Notably, in the PBMC fraction, where neutrophils are limited, natural killer (NK) cells became the major source of innate CCL4 production. TLR7/8a-mediated IFN{gamma} induction by early NK cells was mapped in PBMCs, which was limited in WB. Considering such distinctions, we hypothesized that deep phenomics employing a clinical sample that has not been manipulated, i.e., WB, may be additive in translating in vitro innate fingerprinting into in vivo biology.

immunology↗

bioRxiv2024

Immune-profiling of T helper 1 (Th1), Th2 and Th17 signatures in murine splenocytes by targeting intracellular cytokines

Functional cytokines shape both innate and adaptive immune responses in the host after infection or immunization. Deep immunophenotyping of the key functional cytokine signatures associated with T cells in murine lymphoid tissue, especially in the spleen, is challenging. Using spectral flow cytometry, we developed a 17-parameter panel to profile major immune cell subsets along with T cells, memory phenotypes and functional cytokines in murine splenocytes in steady state as well as in stimulated conditions. This panel dissects the memory T cell compartment via CD62L and CD44 expression after mitogen stimulation. To profile T helper (Th) cells distribution after mitogen stimulation, established Th1 markers IFN{gamma}, TNF and IL-2; Th2 markers IL-4/5 and the Th17 marker, IL-17, are included. This optimized multicolor spectral flow panel allows a detailed immune profiling of functional cytokines in the murine T cell compartment and might be useful for exploratory analysis of how these functional cytokines shape host immunity after infection or vaccination. Our panel could be easily modified, if researchers wish to tailor the panel to their specific needs.

immunology↗

bioRxiv2022

Reduced SARS-CoV-2 mRNA vaccine immunogenicity and protection in mice with diet-induced obesity and insulin resistance.

BackgroundObesity and Type 2 Diabetes Mellitus (T2DM) are associated with an increased risk of severe outcomes from infectious diseases, including COVID-19. These conditions are also associated with distinct responses to immunization, including an impaired response to widely used SARS-CoV-2 mRNA vaccines. ObjectiveTo establish a connection between reduced immunization efficacy via modeling the effects of metabolic diseases on vaccine immunogenicity that is essential for the development of more effective vaccines for this distinct vulnerable population. MethodsWe utilized a murine model of diet-induced obesity and insulin resistance to model the effects of comorbid T2DM and obesity on vaccine immunogenicity and protection. ResultsMice fed a high-fat diet (HFD) developed obesity, hyperinsulinemia, and glucose intolerance. Relative to mice fed a normal diet (ND), HFD mice vaccinated with a SARS-CoV-2 mRNA vaccine exhibited significantly lower anti-spike IgG titers, predominantly in the IgG2c subclass, associated with a lower type 1 response, along with a 3.83-fold decrease in neutralizing titers. Furthermore, enhanced vaccine-induced spike-specific CD8+ T cell activation and protection from lung infection against SARS-CoV-2 challenge were seen only in ND mice but not in HFD mice. ConclusionWe demonstrate impaired immunity following SARS-CoV-2 mRNA immunization in a murine model of comorbid T2DM and obesity, supporting the need for further research into the basis for impaired anti-SARS-CoV-2 immunity in T2DM and investigation of novel approaches to enhance vaccine immunogenicity among those with metabolic diseases. Capsule summaryObesity and type 2 diabetes impair SARS-CoV-2 mRNA vaccine efficacy in a murine model.

immunology↗

bioRxiv2022

Adjuvant Discovery via a High Throughput Screen using Human Primary Mononuclear Cells

We describe a methodology utilizing high-throughput and high-content screening for novel adjuvant candidates that was used to screen a library of [~]2,500 small molecules via a 384-well quantitative combined cytokine and flow cytometry immunoassay in primary human peripheral blood mononuclear cells (PBMCs) from 4 healthy adult study participants. Hits were identified based on their induction of soluble cytokine (TNF, IFN{gamma} and IL-10) secretion and PBMC maturation (CD 80/86, Ox40, and HLA-DR) in at least two of the four donors screened. From an initial set of 197 compounds identified using these biomarkers--an 8.6% hit rate--we downselected to five scaffolds that demonstrated robust efficacy and potency in vitro and evaluated the top hit, vinblastine sulfate, for adjuvanticity in vivo. Vinblastine sulfate significantly enhanced murine humoral responses to recombinant SARS-CoV-2 spike protein, including a four-fold enhancement of IgG titer production when compared to treatment with the spike antigen alone. Overall, we outline a methodology for discovering immunomodulators with adjuvant potential via high-throughput screening of PBMCs in vitro that yielded a lead compound with in vivo adjuvanticity. MotivationVaccines are a key biomedical intervention to prevent the spread of infectious diseases, but their efficacy can be limited by insufficient immunogenicity and nonuniform reactogenic profiles. Adjuvants are molecules that potentiate vaccine responses by inducing innate immune activation. However, there are a limited number of adjuvants in approved vaccines, and current approaches for preclinical adjuvant discovery and development are inefficient. To enhance adjuvant identification, we developed a protocol based on in vitro screening of human primary leukocytes.

immunology↗

bioRxiv2022

Shaping neonatal immunization by tuning delivery of synergistic adjuvants via nanocarriers

Adjuvanted nanocarrier-based vaccines hold substantial potential for applications in novel early-life immunization strategies. Here, via mouse and human age-specific in vitro modelling, we identified the combination of a small molecule STING agonist (2'3'-cyclic GMP-AMP, cGAMP) and a TLR7/8 agonist (CL075) to drive synergistic activation of neonatal dendritic cells and precision CD4 Th cell expansion via the IL-12/IFN{gamma} axis. We further demonstrate that vaccination of neonatal mice with quadrivalent influenza recombinant hemagglutinin (rHA) and an admixture of two polymersome (PS) nanocarriers separately encapsulating-cGAMP (cGAMP-PS) and CL075 (CL075-PS) drove robust T helper (Th)1 bias, high frequency of T follicular helper (TFH) cells and germinal center B (GC B) cells along with IgG2c-skewed humoral response in vivo. Dual loaded cGAMP/CL075-PSs did not outperform admixed cGAMP-PSs and CL075-PSs in vivo. These data validate an optimally designed adjuvantation system, via age-selected small molecule synergy and a multi-component nanocarrier formulation, as an effective approach to induce type 1 immune responses in early life.

immunology↗

bioRxiv2021

An adjuvanted SARS-CoV-2 RBD nanoparticle elicits neutralizing antibodies and fully protective immunity in aged mice

Development of affordable and effective vaccines that can also protect vulnerable populations such as the elderly from COVID-19-related morbidity and mortality is a public health priority. Here we took a systematic and iterative approach by testing several SARS-CoV-2 protein antigens and adjuvants to identify a combination that elicits neutralizing antibodies and protection in young and aged mice. In particular, SARS-CoV-2 receptorbinding domain (RBD) displayed as a protein nanoparticle (RBD-NP) was a highly effective antigen, and when formulated with an oil-in-water emulsion containing Carbohydrate fatty acid MonoSulphate derivative (CMS) induced the highest levels of cross-neutralizing antibodies compared to other oil-in-water emulsions or AS01B. Mechanistically, CMS induced antigen retention in the draining lymph node (dLN) and expression of cytokines, chemokines and type I interferon-stimulated genes at both injection site and dLN. Overall, CMS:RBD-NP is effective across multiple age groups and is an exemplar of a SARS-CoV-2 subunit vaccine tailored to the elderly.

immunology↗

bioRxiv2021

Alum:CpG adjuvant enables SARS-CoV-2 RBD-induced protection in aged mice and synergistic activation of human elder type 1 immunity

Global deployment of vaccines that can provide protection across several age groups is still urgently needed to end the COVID-19 pandemic especially for low- and middle-income countries. While vaccines against SARS-CoV-2 based on mRNA and adenoviral-vector technologies have been rapidly developed, additional practical and scalable SARS-CoV-2 vaccines are needed to meet global demand. In this context, protein subunit vaccines formulated with appropriate adjuvants represent a promising approach to address this urgent need. Receptor-binding domain (RBD) is a key target of neutralizing antibodies (Abs) but is poorly immunogenic. We therefore compared pattern recognition receptor (PRR) agonists, including those activating STING, TLR3, TLR4 and TLR9, alone or formulated with aluminum hydroxide (AH), and benchmarked them to AS01B and AS03-like emulsion-based adjuvants for their potential to enhance RBD immunogenicity in young and aged mice. We found that the AH and CpG adjuvant formulation (AH:CpG) demonstrated the highest enhancement of anti-RBD neutralizing Ab titers in both age groups ([~]80-fold over AH), and protected aged mice from the SARS-CoV-2 challenge. Notably, AH:CpG-adjuvanted RBD vaccine elicited neutralizing Abs against both wild-type SARS-CoV-2 and B.1.351 variant at serum concentrations comparable to those induced by the authorized mRNA BNT162b2 vaccine. AH:CpG induced similar cytokine and chemokine gene enrichment patterns in the draining lymph nodes of both young adult and aged mice and synergistically enhanced cytokine and chemokine production in human young adult and elderly mononuclear cells. These data support further development of AH:CpG-adjuvanted RBD as an affordable vaccine that may be effective across multiple age groups. One Sentence SummaryAlum and CpG enhance SARS-CoV-2 RBD protective immunity, variant neutralization in aged mice and Th1-polarizing cytokine production by human elder leukocytes.

immunology↗

bioRxiv2019

The TLR5 agonist flagellin modifies phenotypical and enhances functional activation of lung mucosal antigen presenting cells in neonatal mice

Intranasal mucosal vaccines are of interest in that they may induce protective mucosal immune responses. Activation of lung antigen presenting cells (APCs), a phenotyoically and functionally heterogeneous cell population located at distinct mucosal sites, may be key to the immunogenicity of such vaccines. Characterizing responsiveness of newborn lung APCs to adjuvants may inform design of efficacious intranasal vaccines for early life, when most infections occur. We characterized APCs from neonatal (<7 days of life) and adult (6-8 weeks of age) mice. Neonatal mice displayed a relatively high abundance of alveolar macrophages (AMs), with lower percentages of plasmacytoid dendritic cells (pDCs), CD103+ (cDC1) and CD11b+ (cDC2) DCs. Furthermore, neonatal CD103+ and CD11b+ DC subsets demonstrated an inverse expression of maturation markers as compared to adult mice. Upon stimulation of lung APC subsets with a panel of pattern recognition receptor (PRR), including TLR and STING, agonists, CD11c+ enriched cells from neonatal and adult mice lungs demonstrated distinct maturation profiles. The TLR5 ligand, flagellin, was most effective at activating neonatal lung APCs, inducing significantly higher expression of maturation markers on CD103+ (cDC1) and CD11b+ (cDC2) subsets. Intranasal administration of flagellin induced a distinct migration of CD103+ and CD11b+ DC subsets to the mediastinal lymph nodes (mLNs) of neonatal mice. Overall, these findings highlight age specific differences in the maturation and responsiveness of lung APC subsets to different PRR agonists. The unique efficacy of flagellin in enhancing lung APC activity suggests that it may serve as an effective adjuvant for early life mucosal vaccines.

immunology↗