Additive effects of rapamycin and aspirin on dendritic cell allostimulatory capacity

Phenolic Acids and Prevention of Cognitive Decline: Polyphenols with a Neuroprotective Role in Cognitive Disorders and Alzheimer's Disease

Cognitive impairment, also known as cognitive decline, can occur gradually or suddenly and can be temporary or more permanent. It represents an increasingly important public health problem and can depend on normal aging or be linked to different neurodegenerative disorders, including Alzheimer's disease (AD). It is now well-established that lifestyle factors including dietary patterns play an important role in healthy aging as well as in the prevention of cognitive decline in later life. Among the natural compounds, dietary polyphenols including phenolic acids have been recently the focus of major attention, with their supplementation being associated with better cognitive status and prevention of cognitive decline. Despite their therapeutic potential, human studies investigating the relation between phenolic acids intake and cognitive outcomes are rather scarce. In this review, we provide preclinical evidence that different dietary polyphenols such as rosmarinic acid, ellagic acid, and cinnamic aldehyde can exert neuroprotective and pro-cognitive activities through different molecular mechanisms including the modulation of pro-oxidant and antioxidant machinery as well as inflammatory status. Future and more numerous in vivo studies are needed to strengthen the promising results obtained at the preclinical level. Despite the excellent pharmacokinetic properties of phenolic acids, which are able to be accumulated in the brain at pharmacologically relevant levels, future studies should also identify which among the different metabolites produced as a consequence of phenolic acids' consumption may be responsible for the potential neuroprotective effects of this subgroup of polyphenols.

Phenolic Acids and Prevention of Cognitive Decline: Polyphenols with a Neuroprotective Role in Cognitive Disorders and Alzheimer's Disease

Cognitive impairment, also known as cognitive decline, can occur gradually or suddenly and can be temporary or more permanent. It represents an increasingly important public health problem and can depend on normal aging or be linked to different neurodegenerative disorders, including Alzheimer's disease (AD). It is now well-established that lifestyle factors including dietary patterns play an important role in healthy aging as well as in the prevention of cognitive decline in later life. Among the natural compounds, dietary polyphenols including phenolic acids have been recently the focus of major attention, with their supplementation being associated with better cognitive status and prevention of cognitive decline. Despite their therapeutic potential, human studies investigating the relation between phenolic acids intake and cognitive outcomes are rather scarce. In this review, we provide preclinical evidence that different dietary polyphenols such as rosmarinic acid, ellagic acid, and cinnamic aldehyde can exert neuroprotective and pro-cognitive activities through different molecular mechanisms including the modulation of pro-oxidant and antioxidant machinery as well as inflammatory status. Future and more numerous in vivo studies are needed to strengthen the promising results obtained at the preclinical level. Despite the excellent pharmacokinetic properties of phenolic acids, which are able to be accumulated in the brain at pharmacologically relevant levels, future studies should also identify which among the different metabolites produced as a consequence of phenolic acids' consumption may be responsible for the potential neuroprotective effects of this subgroup of polyphenols.

Aspirin Attenuates Cardiac Allograft Rejection by Inhibiting the Maturation of Dendritic Cells via the NF-κB Signaling Pathway

Background: Dendritic cells (DCs) serve as an important part of the immune system and play a dual role in immune response. Mature DCs can initiate immune response, while immature or semi-mature DCs induce immune hyporesponsiveness or tolerance. Previous studies have shown that aspirin can effectively inhibit the maturation of DCs. However, the protective effect of aspirin on acute cardiac allograft rejection has not been studied. The aim of this study was to elucidate the effect of aspirin exert on allograft rejection. Methods: The model of MHC-mismatched (BALB/c to B6 mice) heterotopic heart transplantation was established and administered intraperitoneal injection with aspirin. The severity of allograft rejection, transcriptional levels of cytokines, and characteristics of immune cells were assessed. Bone marrow-derived dendritic cells (BMDCs) were generated with or without aspirin. The function of DCs was determined via mixed lymphocyte reaction (MLR). The signaling pathway of DCs was detected by Western blotting. Results: Aspirin significantly prolonged the survival of cardiac allograft in mouse, inhibited the production of pro-inflammatory cytokines and the differentiation of effector T cells (Th1 and Th17), as well as promoted the regulatory T cells (Treg). The maturation of DCs in the spleen was obviously suppressed with aspirin treatment. In vitro, aspirin decreased the activation of NF-κB signaling of DCs, as well as impeded MHCII and co-stimulatory molecules (CD80, CD86, and CD40) expression on DCs. Moreover, both the pro-inflammatory cytokines and function of DCs were suppressed by aspirin. Conclusion: Aspirin inhibits the maturation of DCs through the NF-κB signaling pathway and attenuates acute cardiac allograft rejection.

Recent discoveries in dendritic cell tolerance-inducing pharmacological molecules

Dendritic cells (DCs) represent one of the most important biological tools for cellular immunotherapy purposes. There are an increasing number of phase I and II studies, where regulatory or tolerogenic DCs (TolDCs) are utilized as negative vaccines, with the aim of inducing tolerogenic outcomes in patients with various autoimmune or chronic-inflammatory diseases, as well as in transplant settings. The induction of tolerogenic properties in DCs can be achieved by altering their activation state toward expression of immunosuppressive elements and/or by achieving resistance to maturation, which leads to insufficient co-stimulatory signal delivery and inability to efficiently present antigens. In the past, one of the most efficient ways to induce DC tolerance has been the application of selected pharmacological agents which actively induce a tolerogenic transcription program or inhibit major pro-inflammatory transcription factors such as Nf-κB. Important examples include immunosuppressants such as different corticosteroids, vitamin D₃, rapamycin and others. The quality of TolDCs induced by different approaches is becoming a vital issue and recent evidence suggests substantial heterogeneity between variously-generated TolDCs as evidenced by their transcriptomic profile and function. The possibility of various "flavors" of TolDCs encourages future research in discovery of Tol-DC inducing agents to enrich various ways of DC manipulation. This would enable a broader range of tools to manipulate DC toward specific characteristics desirable in different disease settings. In recent years, several novel small molecules have been identified with the capacity to promote DC tolerogenic characteristics. In this review, we will present and discuss these novel findings and also highlight novel understandings of tolerogenic mechanisms by which DC tolerogenicity is induced by already established agents.

Update on Dendritic Cell-Induced Immunological and Clinical Tolerance

Dendritic cells (DCs) as highly efficient antigen-presenting cells are at the interface of innate and adaptive immunity. As such, they are key mediators of immunity and antigen-specific immune tolerance. Due to their functional specialization, research efforts have focused on the characterization of DCs subsets involved in the initiation of immunogenic responses and in the maintenance of tissue homeostasis. Tolerogenic DCs (tolDCs)-based therapies have been designed as promising strategies to prevent and control autoimmune diseases as well as allograft rejection after solid organ transplantation (SOT). Despite successful experimental studies and ongoing phase I/II clinical trials using autologous tolDCs in patients with type 1 diabetes, rheumatoid arthritis, multiple sclerosis, and in SOT recipients, additional basic research will be required to determine the optimal DC subset(s) and conditioning regimens for tolDCs-based treatments in vivo. In this review, we discuss the characteristics of human DCs and recent advances in their classification, as well as the role of DCs in immune regulation and their susceptibility to in vitro or in vivo manipulation for the development of tolerogenic therapies, with a focus on the potential of tolDCs for the treatment of autoimmune diseases and the prevention of allograft rejection after SOT.

The Neuroprotective Effects of Phenolic Acids: Molecular Mechanism of Action

The neuroprotective role of phenolic acids from food has previously been reported by many authors. In this review, the role of phenolic acids in ameliorating depression, ischemia/reperfusion injury, neuroinflammation, apoptosis, glutamate-induced toxicity, epilepsy, imbalance after traumatic brain injury, hyperinsulinemia-induced memory impairment, hearing and vision disturbances, Parkinson’s disease, Huntington’s disease, anti-amyotrophic lateral sclerosis, Chagas disease and other less distributed diseases is discussed. This review covers the in vitro, ex vivo and in vivo studies concerning the prevention and treatment of neurological disorders (on the biochemical and gene expression levels) by phenolic acids.