In this review, special emphasis will be placed on red grape polyphenols for their antioxidant and anti-inflammatory activities. Therefore, their capacity to inhibit major pathways responsible for activation of oxidative systems and expression and release of proinflammatory cytokines and chemokines will be discussed. Furthermore, regulation of immune cells by polyphenols will be illustrated with special reference to the activation of T regulatory cells which support a tolerogenic pathway at intestinal level. Additionally, the effects of red grape polyphenols will be analyzed in obesity, as a low-grade systemic inflammation. Also, possible modifications of inflammatory bowel disease biomarkers and clinical course have been studied upon polyphenol administration, either in animal models or in clinical trials. Moreover, the ability of polyphenols to cross the blood–brain barrier has been exploited to investigate their neuroprotective properties. In cancer, polyphenols seem to exert several beneficial effects, even if conflicting data are reported about their influence on T regulatory cells. Finally, the effects of polyphenols have been evaluated in experimental models of allergy and autoimmune diseases. Conclusively, red grape polyphenols are endowed with a great antioxidant and anti-inflammatory potential but some issues, such as polyphenol bioavailability, activity of metabolites, and interaction with microbiota, deserve deeper studies.

Coronaviruses (CoVs) possess an enveloped, single, positive-stranded RNA genome which encodes for four membrane proteins, namely spike (S), envelope (E), membrane (M) and nucleocapsid (N) proteins 3-5 [1]. With regard to pathogenicity, S proteins are essential for viral entry into host cells [2, 3]. SARS-CoV binds to the angiotensin-converting enzyme (ACE)2 which is present on nonimmune cells, such as respiratory and intestinal epithelial cells, endothelial cells, kidney cells (renal tubules) and cerebral neurons and immune cells, such as alveolar monocytes/macrophages [4-6]. Of note, CD209L or liver/lymph node special intercellular adhesion molecule-3-grabbing non-integrin (SIGN) and dendritic cell (DC)-SIGN are alternative receptors for SARS-CoV but with lower affinity [7]. In the case of MERS-CoV, S proteins bind to the host cell receptor dipeptidyl peptidase 4 (DPP4 or CD26) which is broadly expressed on intestinal, alveolar, renal, hepatic and prostate cells as well as on activated leukocytes [8]. Then, viruses replicate in target cells with release of mature virions, which, in turn, invade new target cells [9]. Evidence has been provided that SARSCoV proteins are cleaved into two subunits, S1 and S2, respectively, and the amino acids 318-510 of the S1 represent the receptor-binding domain (RBD) which binds to ACE2 [10, 11]. Quite importantly, in the context of RBD there is the receptor-binding motif (RBM) (amino acids 424- 494), which accounts for complete binding to ACE2 [11]. Moreover, by means of two residues at positions 479 and 487 RBD allows virus progression and tropism [10, 11]. In the case of MERSCoV, its RBM binds to DPP4 with residues 484-567, thus, suggesting that its RBD differs from that of SARS-CoV [12, 13]. In a very recent paper, Wan and associates [14] have investigated the receptor recognition by COVID-19 (a new term to indicate the 2019-nCoV in Wuhan) on the bases of structural studies. In this respect, the sequence of COVID-19 RBM is similar to that of SARSCoV, thus, implicating that ACE2 may represent the binding receptors for COVID-19. Furthermore, gln493 residue of COVID-19 RBM seems to allow interaction with human ACE2, thus, suggesting the ability of this virus to infect human cells. According, to Wan and associates structural analysis [14], COVID-19 binds to human ACE2 with a lesser efficiency than human SARS-CoV (2002) but with higher affinity than human SARS-CoV (2003). Furthermore, same authors predicted that a single mutation at the 501 position may enhance the COVID-19 RBD binding capacity to human ACE2 and this evolution should be monitored in infected patients [14]. These predictive findings by Wan and associates [14] are confirmed by two contemporary studies by Letko and Muster [15] and Peng and associates [16]. In particular, the report by Peng and associates [16], points out the possible origin of COVID-19 from bats [16]. From a pathogenic point of view, evidence has been provided that binding of S2 to ACE2 receptor leads to its down-regulation with subsequent lung damage in the course of SARS-CoV infection [17]. Down-regulation of ACE2 causes excessive production of angiotensin (ANG) II by the related enzyme ACE with stimulation of ANG type 1a receptor (AT1R) and enhanced lung vascular permeability [18]. In particular, same authors have reported that recombinant ACE2 could attenuate severe acute lung injury in mice [18]. Moreover, Battle and associates [19] also proposed to use already available recombinant ACE2 for intercepting COVID-19 and attenuating infection. In the previous paragraphs, the presence of ACE2 on immune cells has been pointed out and, by analogy to epithelial cells, this receptor may also be down-regulated following viral entry. Therefore, in CoV-infected animal models and in infected humans further investigations are required to clarify a possible reduced expression of ACE2 on immune cells. In fact, in the course of SARS-CoV infection, a number of immune disorders have been detected. Three reports have demonstrated the ability of CoV to inhibit interferon (IFN)- production in the course of SARS acting as IFN antagonist [20-22]. In senescent Balb/c mice, depletion of T lymphocytes is associated to more severe interstitial pneumonitis and delayed clearance of SARS-CoV, thus, suggesting a protective role played by these cells [23]. In this connection, both SARS-CoV and MERS-CoV have been shown to induce T cell apoptosis, thus, aggravating the clinical course of disease [24, 25]. Quite interestingly, memory CD8+ T cells specific for SARS-CoV M and N proteins have been detected up to 11 years post-infection [26]. As far as humoral immune responsiveness is concerned, evidence has been provided that S1 subunit from MERS-CoV is highly immunogenic in mice [27]. Moreover, monoclonal antibodies have been shown to be highly neutralizing against MERS-CoV replication and endowed with post exposure effectiveness in susceptible mice [28, 29]. Human neutralizing antibodies have also been isolated from a recovered patient, thus, suggesting the role of humoral immunity in the control of the persistence of CoV in the host [30]. In particular, IgG response occurs early in infection and its prolonged production may serve for virus clearance during recovery also in view of the absence of viremia in convalescent sera from SARS patients [31]. According to current literature, severity of COVID-19 infection correlates with lymphopenia and patients who died from COVID-19 had lower lymphocyte counts when compared to survivors [32, 33]. These data suggest that lymphocyte-mediated anti-viral activity is poorly effective against COVID-19. Despite lymphopenia, evidence for an exaggerate release of proinflammatory cytokines [interleukin (IL)-1 and IL-6] has been reported in the course acute respiratory syndrome in COVID19 infected patients, thus, aggravating the clinical course of disease [34]. As recently reported, during COVID-19 pandemic in...

Background: Olive tree leaves have been used in the Mediterranean area as traditional medicine in virtue of their healthy effects. Olive leaf extracts (OLEs) contain higher amounts of polyphenols than those detected in the extra virgin olive oil and fruit. Several lines of evidence support the cardioprotective, anti-oxidant and anti-inflammatory activities exerted by OLEs. Methods: Peripheral blood mononuclear cells from twenty-five healthy donors were cultured in the presence of 3 µg of two OLE extracts, extract A (resuspended in water) and extract B (resuspended in 70% ethanol). After harvesting, cell pellets were used for cytofluorimetric phenotyping, while supernatants were assayed for cytokine release by means of ELISA. Furthermore, in the same supernatants nitric oxide (NO) content was determined. Results: Both extracts, but especially extract A, increased absolute numbers of CD8+ and natural killer (NK) cells. In addition, an increased production of interferon (IFN)-γ by both extracts as an expression of T helper (h)1 activation was observed. Finally, both extracts enhanced NO release. Conclusion: OLEs, and mostly extract A, are able to in vitro modify healthy human immune response by increasing IFN-γ production which seems to be associated to the higher absolute numbers of CD8+ and NK cells and this may suggest a reinforcement of the anti-tumor activity. Furthermore, increased levels of NO may indicate the potential cardioprotective effects exerted by OLEs in virtue of their vasodilation dependent activity. Finally, OLEs are able to maintain the equilibrium between T regulatory cells and Th17 cells as evidenced by unmodified levels of interleukin (IL)-IL-10 and IL-17, respectively. : In the light of these results, OLEs are potential therapeutic compounds for the treatment of chronic inflammatory disease, also preventing cardiovascular event outcome.

The in vitro ability of polyphenols, extracted from red grape, to modulate peripheral blood mononuclear cell responses has been evaluated in 20 obese (Ob) people. With regard to cytokine release in response to phorbol myristate acetate (PMA), levels of interleukin‐2 (IL‐2), interferon‐γ (IFN‐γ), IL‐4, IL‐10, and IL‐17 were higher in the Ob than in healthy (H) subjects. Vice versa, IL‐21 concentrations were detected only in H people but they were undetectable in the Ob counterpart. In general terms, levels of IL‐1β, IL‐6, IL‐8, and tumor necrosis factor‐α were higher in Ob people when compared to H controls. On the other hand, polyphenols did not modify IFN‐γ, IL‐4, and IL‐17 levels. However, an increase in IL‐2 was observed in H individuals, whereas its levels were decreased in the Ob counterpart. Polyphenols significantly increased IL‐10 release from H donors, whereas a trend to increase was observed in Ob people. In addition, polyphenols were able to significantly increase levels of H IL‐21, while this was not the case in Ob people. Since IL‐21 is an inducer of Th17 cells, it is likely that polyphenols may suppress the sources of this cytokine via production of IL‐10. Accordingly, polyphenols decreased IL‐1β and IL‐6 release in comparison to H controls.

Background & Objectives: In old people, both innate and adaptive immune responses are impaired, thus leading to a condition of systemic inflamm-ageing, even including the involvement of the central nervous system (CNS). Aims: Here main mechanisms of the immune ageing and neuro-inflammation will be discussed along with dietary approaches for the modulation of aged related diseases. Discussion: Neuroinflammation is caused by the passage of inflammatory mediators through the brain blood barrier to CNS. Then, in the brain, antigenic stimulation of microglia and/or its activation by peripheral cytokines lead to a robust production of free radicals with another wave of pro-inflammatory cytokines which, in turn, causes massive neuronal damage. Also infiltrating T cells [T helper (h) and T cytotoxic cells] contribute to neuronal damage, too. Additionally, a peripheral imbalance between inflammatory Th17 cells and anti-inflammatory T regulatory cells seems to be prevalent in the aged brain, thus leading to a proinflammatory profile. Alzheimer’s disease, Parkinson’s disease and multiple sclerosis will be described as typical neurodegenerative diseases. Finally, modulation of the immune response thanks to the anti-oxidant and anti-inflammatory effects exerted by dietary products and nutraceuticals in ageing will be discussed. Special emphasis will be placed on polyunsaturated fatty acids, polyphenols, micronutrients and pre-probiotics and synbiotics. Conclusion: Ageing is characterized by a peripheral subversion of the immune system with a condition of inflamm-ageing. Neuroinflammation and neurodegenerative diseases seem to be a central manifestation of a peripheral perturbation of the immune machinery. Dietary products and nutraceuticals may lead to a down-regulation of the oxidative and pro-inflammatory profile in ageing.

Background: Our previous findings demonstrated that in vitro supplementation of polyphenols, extracted from seeds of red grape (Nero di Troia cultivar), to peripheral lymphomonocytes from patients affected by allergic contact dermatitis (ACD) to nickel (Ni) could reduce the release of proinflammatory cytokines and nitric oxide (NO), while increasing the levels of interleukin (IL)-10, an anti-inflammatory cytokine.Objective: To assess whether an intervention with oral administration of polyphenols leads to a reduction of peripheral biomarkers in ACD patients.Methods: At T0, 25 patients affected by ACD to Ni were orally administered with 300 mg polyphenols prodie extracted from seeds of red grape (Nero di Troia cultivar) (NATUR-OX®) for 3 months (T1). The other 25 patients affected by ACD to Ni received placebo only for the same period of time. Serum biomarkers were analyzed at T0 and T1. In both groups, seven dropouts were recorded.Result: At T1 in comparison to T0, in treated patients, values of interferon-γ, IL-4, IL-17, pentraxin 3 and NO decreased, while IL-10 levels increased when compared with T0 values. Conversely, in placebo- treated patients, no modifications of biomarkers were evaluated at T1.Conclusion: Present laboratory data rely on the anti-oxidant, anti-inflammatory and anti-allergic properties of polyphenols.