Nanoparticle delivery of grape seed-derived proanthocyanidins to airway epithelial cells dampens oxidative stress and inflammation

Background

Chronic respiratory diseases, whose one of the hallmarks is oxidative stress, are still incurable and need novel therapeutic tools and pharmaceutical agents. The phenolic compounds contained in grape are endowed with well-recognized anti-oxidant, anti-inflammatory, anti-cancer, and anti-aging activities. Considering that natural anti-oxidants, such as proanthocyanidins, have poor water solubility and oral bioavailability, we have developed a drug delivery system based on solid lipid nanoparticles (SLN), apt to encapsulate grape seed extract (GSE), containing proanthocyanidins.

Methods

Plain, 6-coumarin (6-Coum), DiR- and GSE-loaded SLN were produced with the melt-emulsion method. Physicochemical characterization of all prepared SLN was determined by photon correlation spectroscopy and laser Doppler anemometry. MTT assay (spectrophotometry) and propidium iodide (PI) assay (cytofluorimetry) were used to assess cell viability. Flow cytometry coupled with cell imaging was performed for assessing apoptosis and necrosis by Annexin V/7-AAD staining (plain SLE), cell internalization (6-Coum-SLN) and reactive oxygen species (ROS) production (SLN-GSE). NF-κB nuclear translocation was studied by immunofluorescence. In vivo bio-imaging was used to assess lung deposition and persistence of aerosolized DiR-loaded SLN.

Results

Plain SLN were not cytotoxic when incubated with H441 airway epithelial cells, as judged by both PI and MTT assays as well as by apoptosis/necrosis evaluation. 6-Coum-loaded SLN were taken up by H441 cells in a dose-dependent fashion and persisted into cells at detectable levels up to 16 days. SLN were detected in mice lungs up to 6 days. SLN-GSE possessed 243 nm as mean diameter, were negatively charged, and stable in size at 37 °C in Simulated Lung Fluid up to 48 h and at 4 °C in double distilled water up to 2 months. The content of SLN in proanthocyanidins remained unvaried up to 2 months. GSE-loaded SLN determined a significant reduction in ROS production when added 24–72 h before the stimulation with hydrogen peroxide. Interestingly, while at 24 h free GSE determined a higher decrease of ROS production than SLN-GSE, the contrary was seen at 48 and 72 h. Similar results were observed for NF-κB nuclear translocation.

Conclusions

SLN are a biocompatible drug delivery system for natural anti-oxidants obtained from grape seed in a model of oxidative stress in airway epithelial cells. They feature stability and long-term persistence inside cells where they release proanthocyanidins. These results could pave the way to novel anti-oxidant and anti-inflammatory therapies for chronic respiratory diseases.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1509-4) contains supplementary material, which is available to authorized users.

Review: The role of the liver in the response to LPS: experimental and clinical findings

The liver plays an important physiological role in lipopolysaccharide (LPS) detoxification and, in particular, hepatocytes are involved in the clearance of endotoxin of intestinal derivation. In experimental shock models, tumor necrosis factor (TNF)-α induces hepatocyte apoptosis and lethal effects are due to secreted TNF-α and not to cell-associated TNF-α. An exaggerated production of TNF-α has been reported in murine viral infections, in which mice become sensitized to low amounts of LPS and both interferon (IFN)-γ and IFN-α/β are involved in the macrophage-induced release of TNF-α. The prominent role of LPS and TNF-α in liver injury is also supported by studies of ethanol-induced hepatic damage. In humans, evidence of LPS-induced hepatic injury has been reported in cirrhosis, autoimmune hepatitis, and primary biliary cirrhosis and a decreased phagocytic activity of the reticulo-endothelial system has been found in these diseases. The origin of endotoxemia in hepatitis C virus (HCV) infected patients seems to be multifactorial and LPS may be of exogenous or endogenous derivation. In endotoxemic HCV-positive patients responsive to a combined treatment with IFN-α/ribavirin (RIB), endotoxemia was no longer detected at the end of the therapeutic regimen. By contrast, 48% of the non-responders to this treatment were still endotoxemic and their monocytes displayed higher intracellular TNF-α and interleukin (IL)-1β levels than responders. Moreover, in responders, an equilibrium between IFN-γ and IL-10 serum levels was attained. In the non-responders, serum levels of IL-10 did not increase following treatment. This may imply that an imbalance between T helper (Th)1 and Th2 derived cytokines could be envisaged in the non-responders.

Invited review: Enteric bacteria, lipopolysaccharides and related cytokines in inflammatory bowel disease: biological and clinical significance

Ulcerative colitis (UC) and Crohn's disease (CD) [inflammatory bowel disease (IBD)] are both characterized by an exaggerated immune response at the gut associated lymphoreticular tissue level. Such an abnormal and dysregulated immune response may be directed against luminal and/or enteric bacterial antigens, as also supported by murine models of inflammatory bowel disease (IBD) caused by organisms such as Citrobacter rodentium and Helicobacter hepaticus.

Bacterial endotoxins or lipopolysaccharides (LPS) have been detected in the plasma of IBD patients and an abnormal microflora and/or an increased permeability of the intestinal mucosa have been invoked as cofactors responsible for endotoxemia. At the same time, the evidence that phagocytosis and killing exerted by polymorphonuclear cells and monocytes and the T-cell dependent antibacterial activity are decreased in IBD patients may also explain the origin of LPS in these diseases.

In IBD, pro-inflammatory cytokines and chemokines have been detected in elevated amounts in mucosal tissue and/or in peripheral blood, thus suggesting a monocyte/macrophage stimulation by enteric bacteria and/or their constituents ( e.g. LPS).

On these grounds, in experimental models and in human IBD, anti-cytokine monoclonal antibodies and interleukin receptor antagonists are under investigation for their capacity to neutralize the noxious effects of immune mediators. Finally, the administration of lactobacilli is beneficial in human IBD and, in murine colitis, this treatment leads to a normalization of intestinal flora, reducing the number of colonic mucosal adherent and translocated bacteria.

Immunopathogenesis of neurodegenerative diseases: current therapeutic models of neuroprotection with special reference to natural products

Parkinson disease (PD) and Alzheimer disease (AD) are neurodegenerative processes whose frequency is dramatically increasing in the western world. Both diseases share a common pathogenic denominator characterized by an exaggerated activation of the systemic and cerebral immune system, respectively. For instance, lipopolysaccharides in PD and amyloid beta in AD trigger microglia and astrocytes to release reactive oxygen species (ROS) and proinflammatory cytokines. Infiltrating peripheral T cells once activated in the central nervous system also contribute to the neurodegenerative process. Besides innovative biotherapy, nutraceuticals or functional foods are currently investigated for their neuroprotective activities. Especially, vitamin D and polyphenols, seem to be promising therapeutic tools for inhibiting ROS formation and arresting cytokine-mediated neuroinflammation in PD and AD.

Low grade inflammation as a common pathogenetic denominator in age-related diseases: novel drug targets for anti-ageing strategies and successful ageing achievement

Nowadays, people are living much longer than they used to do, however they are not free from ageing. Ageing, an inexorable intrinsic process that affects all cells, tissues, organs and individuals, is a post-maturational process that, due to a diminished homeostasis and increased organism frailty, causes a reduction of the response to environmental stimuli and, in general, is associated to an increased predisposition to illness and death. However, the high incidence of death due to infectious, cardiovascular and cancer diseases underlies a common feature in these pathologies that is represented by dysregulation of both instructive and innate immunity. Several studies show that a low-grade systemic inflammation characterizes ageing and that inflammatory markers are significant predictors of mortality in old humans. This pro-inflammatory status of the elderly underlies biological mechanisms responsible for physical function decline and age-related diseases such as Alzheimer's disease and atherosclerosis are initiated or worsened by systemic inflammation. Understanding of the ageing process should have a prominent role in new strategies for extending the health old population. Accordingly, as extensively discussed in the review and in the accompanying related papers, investigating ageing pathophysiology, particularly disentangling age-related low grade inflammation, is likely to provide important clues about how to develop drugs that can slow or delay ageing.

Ability of goat milk to modulate healthy human peripheral blood lymphomonocyte and polymorphonuclear cell function: in vitro effects and clinical implications

The in vitro effects of goat's milk from different sources (Jonica, Saanen, and Priska breeds plus a commercial preparation) on healthy human peripheral blood mononuclear cells (PBMCs) were evaluated in terms of nitric oxide (NO) and cytokine release. According to the incubation time (24 h or 48 h) used all milks could induce release of NO from monocytes. In this context, however, in the presence of a commercial milk preparation inhibition of lypopolysaccharide (LPS)-induce NO generation was evident. Also polymorphonuclear cells stimulated with the various milks released detectable amounts of NO. In the case of Priska milk inhibition of LPS-mediated NO generation was observed. Despite a broad array of cytokines tested [Interleukin (IL)-4, IL-5, IL-6, IL-10, IL-12, IL-13, IL-17, Tumor Necrosis Factor (TNF)-alpha, Transforming Growth Factor-beta and Granulocyte Colony Stimulating Factor] only IL-10, TNF-alpha, and IL-6 were released by PBMCs upon stimulation with various milks. Taken together, these data indicate that goat's milk for its capacity to produce NO may exert a cardioprotective and anti-atherogenic effect in consumers. Moreover, induction of proinflammatory (TNF-alpha and IL-6) and anti-inflammatory (IL-10) cytokines suggests the ability of this milk to maintain immune homeostasis in the immunocompromised host (e.g., aged people).

Donkey's and goat's milk consumption and benefits to human health with special reference to the inflammatory status

The environmental impact as well as malnutrition are responsible for an increased incidence of inflammatory diseases with a consequential loss of immune homeostasis. Therefore, administration of nutraceuticals is aimed at reconstituting the immune balance in terms of the so-called immune nutrition. Among many known nutraceuticals, more recently, donkey's and goat's milks have been used as good alternatives to human and bovine milk in various clinical conditions such as allergy, atopy and inflammatory diseases. In fact, both milks possess immunomodulating capacities and release nitric oxide, a potent vasodilator endowed with anti-atherogenic properties. In this review, emphasis will be placed on the consumption of fermented milk and, in particular, on its ability to modulate the aged immune system, even including the intestinal mucosal immune response in elderly. Therefore, for their specific properties donkey's and goat's milk administration to aged people should be encouraged.

Immunological properties of donkey's milk: its potential use in the prevention of atherosclerosis

Donkey's milk is the best substitute of human milk for its content in lactose, proteins, minerals, and omega-3 fatty acids. Here, we have evaluated the effects of colostrum and milk from donkeys (Martina Franca breed) on the function of human peripheral blood mononuclear cells (PBMCs) at different intervals from lactation. Colostrum induced more IgA responses, while milk induced predominantly more IgG responses. Both milk and colostrum induced expression of CD25 and CD69 on PBMCs. The ability to induce release of interleukins (IL) (IL-12, IL-1 beta and IL-10) and tumor necrosis factor-alpha was confined only to milk, while colostrum was devoid of this capacity. Finally, both colostrum and milk induced nitric oxide (NO) release from PBMCs but milk exhibited a greater capacity than colostrum in NO generation. Taken together, these immunological activities exerted by both colostrum and milk from donkeys may be useful in the treatment of human immune-related diseases. In particular, NO induction by donkey's milk may be very useful in the prevention of atherosclerosis, being a strong vasodilator and an effective antimicrobial agent since pathogens and/or their products may play a proatherogenic role.

The role of the liver in the response to LPS: experimental and clinical findings

The liver plays an important physiological role in lipopolysaccharide (LPS) detoxification and, in particular, hepatocytes are involved in the clearance of endotoxin of intestinal derivation. In experimental shock models, tumor necrosis factor (TNF)-alpha induces hepatocyte apoptosis and lethal effects are due to secreted TNF-alpha and not to cell-associated TNF-alpha. An exaggerated production of TNF-alpha has been reported in murine viral infections, in which mice become sensitized to low amounts of LPS and both interferon (IFN)-gamma and IFN-alpha/beta are involved in the macrophage-induced release of TNF-alpha. The prominent role of LPS and TNF-alpha in liver injury is also supported by studies of ethanol-induced hepatic damage. In humans, evidence of LPS-induced hepatic injury has been reported in cirrhosis, autoimmune hepatitis, and primary biliary cirrhosis and a decreased phagocytic activity of the reticulo-endothelial system has been found in these diseases. The origin of endotoxemia in hepatitis C virus (HCV) infected patients seems to be multifactorial and LPS may be of exogenous or endogenous derivation. In endotoxemic HCV-positive patients responsive to a combined treatment with IFN-alpha/ribavirin (RIB), endotoxemia was no longer detected at the end of the therapeutic regimen. By contrast, 48% of the non-responders to this treatment were still endotoxemic and their monocytes displayed higher intracellular TNF-alpha and interleukin (IL)-1beta levels than responders. Moreover, in responders, an equilibrium between IFN-gamma and IL-10 serum levels was attained. In the non-responders, serum levels of IL-10 did not increase following treatment. This may imply that an imbalance between T helper (Th)1 and Th2 derived cytokines could be envisaged in the non-responders.

Immune abnormalities and endotoxemia in patients with ulcerative colitis and in their first degree relatives: attempts at neutralizing endotoxin-mediated effects

Proinflammatory cytokines released from monocytes/macrophages, in particular tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6, and IL-8 seem to play an important role in Inflammatory Bowel Disease (ulcerative colitis and Crohn's disease). Endotoxins or lipopolysaccharides, derived from the outer membrane of Gram-negative bacteria interact with CD14 on surface membrane of macrophages, thus triggering a signal cascade, which leads to the production and release of proinflammatory cytokines, particularly TNF-alpha. Therefore, in IBD, lipopolysaccharides could play a pathogenic role. In this respect, plasma endotoxins have been demonstrated in a not negligible percentage of patients with ulcerative colitis and in their unaffected relatives. The presence of circulating endotoxins could be due, at least in part, to the impaired natural immunity in either patients with ulcerative colitis or in their first degree unaffected relatives. Lactoferrin is an iron-binding glycoprotein, which binds to the lipid A region of lipopolysaccharide with a high affinity and this interaction prevents the binding of lipopolysaccharide to CD14, thus inhibiting the release of proinflammatory cytokines. Therefore, based on the possible pathogenic role exerted by endotoxins in ulcerative colitis, lactoferrin may deserve attention as a possible therapeutical agent in experimental models of Inflammatory Bowel Disease.

Modifications of the immune responsiveness in patients with autoimmune thyroiditis: evidence for a systemic immune alteration

Hashimoto's thyroiditis, the most common form of autoimmune thyroid disease, is characterised by lymphocytic infiltration of the thyroid gland, gradual destruction of the organ and production of thyroid specific auto antibodies (antithyroid peroxidase and antithyroglobulin antibodies). There are evidences that cast doubt on the pathogenetic role of these antibodies in thyroid autoimmunity. It is very likely that cellular destruction is mediated by other cellular mechanisms, such as auto reactive T-lymphocytes, natural killer and cytokines. However, other studies performed in animal models have led to the conclusion that organ specific autoimmune thyroiditis should be regarded as a polygenic disease with a penetrance that is strongly influenced by environmental factors. According to our recent results, patients affected by autoimmune thyroiditis exhibited a decreased percentage of NK and CD25 + bearing cells significantly in comparison to normal controls. Altogether these data indicated that in the patients with autoimmune thyroid disease a certain degree of peripheral immune deficiency was present.

Modifications of the immune responsiveness in patients with hepatitis C virus infection following treatment with IFN-alpha/ribavirin

The balance between T helper (h)1 and Th2 responsiveness seems to represent a key event in the evolution of hepatitis C virus (HCV) infection. In particular, Th1 cytokines [interleukin (IL-2) and interferon (IFN-gamma)] have been demonstrated to mediate the antiviral immune response. Serum levels of Th1 cytokines (IL-2 and IFN-gamma) as well as of Th2 products (IL-4 and IL-10) were determined in a group of HCV-positive patients before and after treatment with IFN-alpha and Ribavirin (RIB). Results indicate that responder patients exhibited increased levels of IFN-gamma and IL-10, while this enhancement was not observed in non-responder patients. In this respect, the major effect exerted by the combined therapy with IFN-alpha/RIB could be represented by the attainment of a re-equilibrium between inflammatory (Th1) and antiinflammatory (Th2) mechanisms. In this framework, according to current literature, novel therapeutical approaches to treat HCV infection are represented by administration of recombinant IL-2 and IL-10.

Biological and clinical significance of endotoxemia in the course of hepatitis C virus infection

Endotoxins or lipopolysaccharides (LPS), major components of the cell wall of Gram-negative bacteria, once released from the bacterial outer membrane bind to specific receptors and, in particular, to a membrane-bound receptor, the CD14 (mCD14) and the toll-like receptor 4 present on monocytes/ macrophages. In turn, LPS-activated monocytes/ macrophages release in the host tissue an array of so-called proinflammatory cytokines and, among them, Tumor Necrosis Factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, IL-8 and IL-12 are the major mediators. Before therapy (To) and at the end of 6-month interferon (IFN)-alpha/Ribavirin (RIB) treatment (T6), circulating endotoxin levels were measured in responder and non responder HCV+ patients. At T0, 57% of the non responders were endotoxin-positive and had, on average, 54 pg/ml of plasma LPS while in 50% of the responder patients endotoxin were found with an average of 29 pg/ml. At T6, in responders LPS were no longer detectable, while in 42% of the non responders LPS were found (average levels 45 pg/ml). In terms of serum cytokine concentration, at T6 IFN-gamma levels when compared to those detected at T0 were increased in both endotoxin-positive and endotoxin-negative patients. However, at T6 IL-10 concentration was significantly increased only in the group of endotoxin-negative subjects (responder patients), in comparison to T0 values. The origin of endotoxemia in HCV+ patients seems to be multifactorial, likely depending on impaired phagocytic functions and reduced T-cell mediated antibacterial activity. In these patients, however, one cannot exclude the passage of LPS from the gut flora to the blood stream, owing a condition of altered intestinal permeability. At the same time, a less efficient detoxification of enteric bacterial antigens at the hepatic level should be taken into consideration. Finally, novel therapeutic attempts aimed to neutralize LPS in the host are discussed.

Helicobacter pylori infection, immune response and vaccination

It is well known that abnormal immune responses may play a pathogenic role in the H. pylori-related gastropathy. Indeed, as far as humoral immune response is concerned, it is still debated whether specific anti-H. pylori antibodies have a protective or noxious effect in infected hosts. Besides proinflammatory cytokines released from macrophages, such as tumor-necrosis factor-a and interleukin-1beta, and IFN-gamma derived from T-helper 1 lymphocytes, also interleukin-10, a product of T-helper 2 lymphocytes with antiinflammatory properties, seems to be surprisingly involved in the pathogenesis of H. pylori-induced gastritis. In addition, lipopolysaccharide derived from the outher membrane of H. pylori acts as a chemoattractant for monocytes and induces release of free radicals, interleukin-1beta, interleukin-6, interleukin-8 and tumor necrosis factor-alpha. On the other hand, H. pylori lipopolysaccharide could be responsible for the increased polyamine concentrations in the gastric mucosa and polyamines, such as putrescine, spermidine and spermine, could be involved in the increased cell proliferation and consequent possible neoplastic transformation of the gastric mucosa. Incubation of peripheral blood mononuclear cells with H. pylori increases significantly the surface expression of CD95 receptor (Fas), thus suggesting that these bacteria are able to induce apoptosis. In animal models, different types of vaccination have been investigated, including stimulation of nasal and rectal lymphoid tissue, as well as adoptive transfer of T cell from donors immunized with H. pylori. However, results obtained are frequently disappointing. In humans, urease of H. pylori was safely used as oral vaccine in the absence or presence of adjuvants with encouraging results. Finally, DNA vaccines could offer in the future advantages for prophylactic H. pylori eradication, especially where population is infected by this microorganism since childhood.

Enteric bacteria, lipopolysaccharides and related cytokines in inflammatory bowel disease: biological and clinical significance

Ulcerative colitis (UC) and Crohn's disease (CD) [inflammatory bowel disease (IBD)] are both characterized by an exaggerated immune response at the gut associated lymphoreticular tissue level. Such an abnormal and dysregulated immune response may be directed against luminal and/or enteric bacterial antigens, as also supported by murine models of inflammatory bowel disease (IBD) caused by organisms such as Citrobacter rodentium and Helicobacter hepaticus. Bacterial endotoxins or lipopolysaccharides (LPS) have been detected in the plasma of IBD patients and an abnormal microflora and/or an increased permeability of the intestinal mucosa have been invoked as cofactors responsible for endotoxemia. At the same time, the evidence that phagocytosis and killing exerted by polymorphonuclear cells and monocytes and the T-cell dependent antibacterial activity are decreased in IBD patients may also explain the origin of LPS in these diseases. In IBD, pro-inflammatory cytokines and chemokines have been detected in elevated amounts in mucosal tissue and/or in peripheral blood, thus suggesting a monocyte/macrophage stimulation by enteric bacteria and/or their constituents (e.g. LPS). On these grounds, in experimental models and in human IBD, anti-cytokine monoclonal antibodies and interleukin receptor antagonists are under investigation for their capacity to neutralize the noxious effects of immune mediators. Finally, the administration of lactobacilli is beneficial in human IBD and, in murine colitis, this treatment leads to a normalization of intestinal flora, reducing the number of colonic mucosal adherent and translocated bacteria.

In vitro effects of naloxone on T-lymphocyte-dependent antibacterial activity in hepatitis C virus (HCV) infected patients and in inflammatory bowel disease (IBD) patients

Naloxone acts as an opioid antagonist, displacing opioid drugs from cellular receptors. Among opioid substances, beta-endorphins are able to bind to several cell receptors, even including those expressed by immune cells. In this respect, evidence has been provided that in the course of viral infections, as well as in patients with ulcerative colitis high levels of beta-endorphins are detectable. Here, peripheral blood lymphocytes (PBL) from 21 HCV infected patients and 14 patients with IBD, respectively, were incubated with Naloxone and Naloxone + Ca2+ in order to evaluate a putative modulation of PBL-mediated antibacterial activity. In fact, previous studies have demonstrated a reduction of this T-cell activity in HCV and IBD patients. In general terms, the above treatment led to a recovery of the depressed antibacterial activity. In some cases, increase in T lymphocyte function was obtained with Naloxone alone, while in other cases the combination Naloxone + Ca2+ gave rise to a restorative effect. Of note, in some instances, lymphocytes were unresponsive to pharmacological modulation. The overall results suggest that beta-endorphins may down modulate T-cell antibacterial response in HCV and in IBD patients by saturating peripheral receptors on immune cells. Therefore, it is likely that Naloxone and/or Naloxone + Ca2+ may displace opioid drugs, thus antagonizing their effects.