Postmortem morphology and viability of human Peyer's patches in distal ileum: a technical note.

The intestinal mucosa contains a highly specialized immune system which plays a central role in the induction of immune reactions. In the small bowel, Gut-Associated Lymphoid Tissue (GALT) is organized in lymphoid aggregates which are known as Peyer's Patches (PP). Even though human PP involvement in systemic immunity has been described, little is known about their anatomy and morphology and viability. The aim of this study was to examine PP according to their macroscopic anatomy, distribution and cell viability after death. Specimens from the distal ileum were obtained from 72 serial autopsy cases: PP were identified and, parts of them were analyzed for histological examination. Moreover, viability of recovered PP cells was assessed by the trypan blue exclusion test. Most of the PP (90%) were situated on the antimesenteric border of ileum, and the greatest density of PP occurred in the most distal segment. The number of PP varied with age, with the maximum number observed in 21- to 30-years old cadavers. Histological examination showed their remarkable architectural preservation at different post-mortem intervals (PMI), while the mucosal surface underwent autolysis. In 56% of cases PP cells were still viable, especially at PMI < 24 hours after death. These data confirm that human PP are still well preserved in a remarkable percentage of cadavers also several hours after death, and their availability may be helpful in various fields of research.

Post-mortem Peyer's patches: their potential application in forensic medicine.

Pro-inflammatory mediators hold important functions in human body in response to infection, trauma and vascular disease. However, their action is down regulated by the release of anti-inflammatory cytokines, thus restoring a balance which reflects the immune status of a given individual. Recent studies have stressed out the importance of circulating levels of cytokines for forensic purposes even if there is a lack of studies regarding the role of post-mortem mucosa-associated lymphoid tissue. In this respect, Peyer's patches (PP), represent one of the most important immunological site of the body and the major component of the gut -associated lymphoid tissue. The aim of this study was to evaluate post-mortem PP immune response in 40 serial autopsy cases of people who died from natural and traumatic death. The study examined spontaneous release of the following cytokines by fresh isolated PP cells: interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, IL-10, IL-6, IL-1 beta, and IL-8. Results will show that higher levels of TNF-alpha, IL-6, IL-1 beta, and IL-8 are statistically correlated with the traumatic death group. From a forensic point of view these data demonstrate that fundamental lymphoid organs, such as PP, may have a potential in diagnosing the cause of death.

Early pathogenesis of atherosclerosis: the childhood obesity.

Obesity represents a chronic inflammatory status and adipocytes release either cytokines or an array of adipokines such as leptin, endowed with immunomodulating and systemic activities. The involvement of cytokines in obesity as well as of the adipokine leptin is supported by the notion that weight reduction normalizes mediators of inflammation. In this framework, we will demonstrate that in obese children, subjected for a period of six months to a hypocaloric diet, reduction of major biochemical and anthropometric parameters correlates with a normalization of immune status. In fact, absolute numbers of CD4+ cells and CD4/CD8 ratio increase, while leptin values fluctuate within normal ranges, being this adipokine involved in the modulation of either innate or adaptive immune responses. In the discussion, the immune abnormalities detected in obesity will be pointed out and emphasis will be placed on the increased frequency of infectious episodes occurring in obese adolescent and adults. Finally, the infectious etiology of obesity will be illustrated in the sense that adipocytes interacting with infectious agents may cause obesity. Taken together, the bulk of available data indicate that childhood obesity should be prevented or reduced to avoid more serious complications in adulthood.

Toll-like receptor signaling mechanisms involved in dendritic cell activation: potential therapeutic control of T cell polarization.

Dendritic cells (DCs) represent a bridge between innate and adaptive immunity, being the maturation process dependent on the binding of pathogen-associated molecular patterns (PAMPs) to Toll-Like Receptors (TLRs) expressed on their surface. TLRs associated to adaptor proteins, following binding to PAMPs, are able to skew specific immune responses towards the T helper (h)(1)- or the Th(2)-type according to the antigenic stimulation involved. Of note, other receptors different from TLRs are expressed on DCs which are also able to recognize PAMPs. Among them, one should mention the DC-specific ICAM-3-grabbing nonintegrin, the mannose receptor, Dectin-1 (the major beta-glucan receptor) and NOD2. Finally, the possibility to interfere therapeutically with the TLR-dependent and -independent signaling pathways in DCs is reviewed. According to current literature, DC activation, their antigen uptake capacity and migration can be enhanced with different experimental procedures whose use in humans is still under evaluation. However, just recently a probiotic cocktail VSL3, successfully used in patients with pouchitis, seems to act on DCs, promoting abundant release of Interleukin-10 in the gut. These novel therapeutic strategies based on the modulation of the signaling pathways in DCs seem to be encouraging for the treatment of inflammatory and autoimmune diseases.

Patients with Hereditary Hemorrhagic Telangectasia (HHT) exhibit a deficit of polymorphonuclear cell and monocyte oxidative burst and phagocytosis: a possible correlation with altered adaptive immune responsiveness in HHT.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare genetic disease characterized by mutations occurring in the endoglin and ALK-1, two receptors of transforming growth factor-beta1. From a pathogenic point of view, a possible involvement of the immune system in HHT has been suggested since a mononuclear cell infiltrate was found around the area of telangiectases. Up until now, no information has been available about the role played by leukocytes in HHT and the mechanisms elicited by secretion of their mediators. However, the fact that a deficit of adaptive immunity in HHT has been reported in a companion paper in this issue will represent a great contribution to the understanding of HHT pathogenesis. The purpose of this study was to evaluate whether patients with HHT manifest also alterations in the innate immune response. Therefore, the phenotype of T, B and natural killer lymphocytes, serum immunoglobulin levels, phagocytosis and oxidative burst activity exerted by polymorphonuclear cells (PMN) and monocytes (MO) were analyzed in 22 patients. Twenty individuals demonstrated single or multiple deficits of PMN and MO functions, while the immunophenotype of lymphocytes and serum concentrations of immunoglobulins were normal. To the best of our knowledge, this is the first demonstration of a reduction in PMN and MO functions in HHT, thus suggesting a higher susceptibility to infectious complications in these patients. The relationship between innate immune deficits and T helper 1 and monocyte-derived cytokine dysfunction in HHT, as previously reported, is discussed.

Drug targets in stress-related disorders.

Nervous and immune systems mutually cooperate via release of mediators of both neurological and immunological derivation. Adrenocorticotropin hormone (ACTH) is a product of the hypothalamus-pituitary adrenal axis (HPAA) which stimulates secretion of corticosteroids from adrenals. In turn, corticosteroids modulate the immune response in virtue of their anti-inflammatory activity. On the other hand, catecholamines, products of the sympathetic nervous system (SNS), regulate immune function by acting on specific beta-adrenergic receptors. Conversely, cytokines released by monocytes/macrophages and lymphocytes, upon antigenic stimulation, are able to cross the blood-brain-barrier, thus modulating nervous functions (e.g., thermoregulation, sleep, and appetite). However, cytokines are locally produced in the brain, especially in the hypothalamus, thus contributing to the development of anorexic, pyrogenic, somnogenic and behavioural effects. Besides pathogens and/or their products, the so-called stressors are able to activate both HPAA and SNS, thus influencing immune responses. In this respect, many studies conducted in medical students taking exams have evidenced an array of stress-induced immune alterations. Phobic disorders and migraine without aura (MWA) represent examples of stress-related disorders in which phagocytic immune deficits, endotoxemia and exaggerated levels of proinflammatory cytokines [Tumor Necrosis Factor-alpha (TNF- alpha), and interleukin- 1 beta] have been detected. Quite interestingly, administration of a thymic hormone could ameliorate clinical symptoms in phobic patients. In MWA patients, a beta-blocker, propranolol, could mitigate migraine, whose cessation coincided with a drop of TNF-alpha serum concentration. In phobic disorders and in MWA, benzodiazepines are very often administered and, in this respect, some of them, such as diazepam, inhibit immune functions, while others, e.g., alprazolam, enhance immune responses. Alprazolam could improve clinical symptoms in MWA patients. Chronic Fatigue Syndrome (CFS) is a disorder whose etiology and pathogenesis are still unknown. In this syndrome both abnormalities of nervous and immune systems have been reported. Despite many immune parameters evaluated in CFS no specific biomarkers of disease have been found. Our own data are in agreement with current literature in that we found decreased levels of serum (IFN)-gamma in these patients, thus indicating a predominance of T helper (h)1 response in CFS. Also leptin, a hormone which regulates food intake, fluctuates within normal ranges in CFS individuals. Quite interestingly, in depressed patients, used as controls, leptinaemia was more elevated than in CFS. Finally, in a series of recent therapeutic trials several immunomodulating agents have been used, such as staphypan Berna, lactic acid bacteria, kuibitang and intravenous immunoglobulin. In conclusion, it seems that major drug targets in stress-related disorders are immune cells in terms of inhibition of proinflammatory cytokines and modulation of Th responses. In particular, according to recent evidences, antidepressants seem to exert beneficial effects in experimental autoimmune neuritis in rats by decreasing IFN- beta release or augmenting NK activity in depressed patients.

Helicobacter pylori organisms induce expression of activation and apoptotic surface markers on human lymphocytes and AGS cells: a cytofluorimetric evaluation.

Human peripheral blood mononuclear cells (PBMCs) were treated with Helicobacter pylori (Hp) organisms alone or with Hp-stimulated AGS cells (a gastric adenocarcinoma cell line). Hp organisms were able per se to increase the percentage of CD8 +/- CD95 +/- cells, while number of CD25+ cells and HLA-DR molecule expression increased following pretreatment with Hp-stimulated AGS cells. A comparison was made with a test system in which PBMCs were stimulated with Escherichia coli (Ec) organisms and colo-cells (a colon carcinoma cell line). In this case, CD95+ cells and CD25+ cells increased when the combination Ec organisms/colo-cells was present in the culture. On the other hand, Hp bacteria in combination with colo-cells were not able to induce activation and/or apoptotic surface markers on PBMCs, while Ec-stimulated AGS cells increased the expression of CD95 on PBMC. Finally, the direct interaction of AGS cells with Hp was able to induce higher expression of CD95 on gastric epithelial cells than Hp-stimulated PBMCs. Taken together, these data support the interplay between bacteria and epithelial cells in the course of Hp-mediated gastropathy.

Antimicrobial and immunoregulatory functions of lactoferrin and its potential therapeutic application.

Lactoferrin is an iron-binding glycoprotein present in various secretions (eg. milk, tears, saliva,pancreatic juice, etc.). It is also stored in specific granules of polymorphonuclear granulocytes from which it is released following activation. Lactoferrin exerts a bactericidal activity by damaging the outermembrane of Gram-negative bacteria, as well as immunoregulatory functions by decreasing the release of interleukin-l (IL- 1), IL-2 and tumor necrosis factor-alpha INF-alpha) and enhancing monocyte and natural killer cell cytotoxicity. Lactoferrin binds with high affinity to lipid A, the toxic moiety of the lipopolysaccharide, or endotoxin from Gram-negative bacteria Lipopolysacchride interaction with monocytes/ma phages results in the production and release of TNF-alpha, that plays an important role in inducing septic shock In this respect, it has recently been demonstrated that lactoferrin inhibits the lipopolysaccharide interaction with CD14 on monocytes/macrophages by competition with the lipopolysaccharide binding protein. Therefore, besides its bactericidal activity, lactoferrin may also act by neutralizing the toxic effects of lipopolysaccharide and this protective role against endotoxin lethal shock has been demonstrated in animal models. Moreover, in vitro and in vivo neutralization of endotoxin by a human lactoferrin-derived peptide was also reported and lactoferrin or lactoferrin-derived peptides could represent useful tools for the treatment of endotoxin-induced septic hock. The recent production and characterization of monoclonal antibodies against different epitopes of human lactoferrin, including monoclonal antibodies selectively neutralizing lactoferrin binding to lipid A, may allow a better elucidation of the consequence of lactoferrin-lipopolysaccharide interaction.