Social determinants of health (SDoH), which encompass the economic, social, environmental, and psychosocial factors that influence health, play a significant role in the development of cardiovascular disease (CVD) risk factors as well as CVD morbidity and mortality. The COVID-19 pandemic and the current social justice movement sparked by the death of George Floyd have laid bare long-existing health inequities in our society driven by SDoH. Despite a recent focus on these structural drivers of health disparities, the impact of SDoH on cardiovascular health and CVD outcomes remains understudied and incompletely understood. To further investigate the mechanisms connecting SDoH and CVD, and ultimately design targeted and effective interventions, it is important to foster interdisciplinary efforts that incorporate translational, epidemiological, and clinical research in examining SDoH-CVD relationships. This review aims to facilitate research coordination and intervention development by providing an evidence-based framework for SDoH rooted in the lived experiences of marginalized populations. Our framework highlights critical structural/socioeconomic, environmental, and psychosocial factors most strongly associated with CVD and explores several of the underlying biologic mechanisms connecting SDoH to CVD pathogenesis, including excess stress hormones, inflammation, immune cell function, and cellular aging. We present landmark studies and recent findings about SDoH in our framework, with careful consideration of the constructs and measures utilized. Finally, we provide a roadmap for future SDoH research focused on individual, clinical, and policy approaches directed towards developing multilevel community-engaged interventions to promote cardiovascular health.

Toll-like receptors (TLRs) are innate immune receptors that have recently emerged as regulators of neuronal survival and developmental neuroplasticity. Adult TLR3-deficient mice exhibited enhanced hippocampus-dependent working memory in the Morris water maze, novel object recognition, and contextual fear-conditioning tasks. In contrast, TLR3-deficient mice demonstrated impaired amygdalarelated behavior and anxiety in the cued fear-conditioning, open field, and elevated plus maze tasks. Further, TLR3-deficient mice exhibited increased hippocampal CA1 and dentate gyrus volumes, increased hippocampal neurogenesis, and elevated levels of the AMPA receptor subunit GluR1 in the CA1 region of the hippocampus. In addition, levels of activated forms of the kinase ERK and the transcription factor CREB were elevated in the hippocampus of TLR3-deficient mice, suggesting that constitutive TLR3 signaling negatively regulates pathways known to play important roles in hippocampal plasticity. Direct activation of TLR3 by intracerebroventricular infusion of a TLR3 ligand impaired working memory, but not reference memory. Our findings reveal previously undescribed roles for TLR3 as a suppressor of hippocampal cellular plasticity and memory retention.oll-like receptors (TLRs) are innate immunity-related receptors that sense pathogen-associated molecular patterns (1) as well as tissue damage-associated molecular patterns (2). Although TLRs are abundant in the immune system, some TLRs are also expressed in central nervous system (CNS) cells where they mediate infection and injury responses (3). For example, activation of TLR4 by bacterial lipopolysaccharide up-regulates proinflammatory cytokine and chemokine production in microglia, and this TLR4 action on microglia is critical for the recruitment of circulating leukocytes into the brain (4). Neurons also express TLRs, and it was recently reported that activation of TLR2 and TLR4 in cortical neurons increases their vulnerability to ischemic injury (5). TLRs mediate innate immune responses, in part, through nuclear factor-κB (NF-κB) and IFN regulatory factor (IRF)-dependent pathways (3). Recent findings suggest that some TLRs modulate neural plasticity. For example, TLR3 inhibits neural progenitor cell (NPC) proliferation in the embryonic mouse telencephalon (6) and inhibits axonal growth in DRG neurons (7). More recently, Peltier et al. (8) found that human neurons are capable of a functional TLR3 signaling mechanism. Here we provide evidence that TLR3 signaling negatively regulates hippocampus-dependent learning and memory and suppresses hippocampal neurogenesis and AMPA receptor expression in CA1 neurons. We further show that constitutive physiological TLR3 signaling suppresses ERK and CREB activities, suggesting a mechanism whereby TLR3 regulates hippocampal neurogenesis and behavioral plasticity. Results TLR3 Deficiency Enhances Hippocampus-Dependent, but ImpairsAmygdala-Dependent, Learning and Memory. To determine whether TLR3 affects cognitive function, we compared spatial memo...