PubMed Health⌕ Search

Biomedical subjects

Emilio Jirillo

Publications and source records attributed to Emilio Jirillo.

13 recordsLinked to original sources
PubMed2006

Stage of primary infection with lymphocytic choriomeningitis virus determines predisposition or resistance of mice to secondary bacterial infections.

We investigated the effect of a primary non-lethal infection with lymphocytic choriomeningitis virus (LCMV) on the course and outcome of a secondary infection with the Gram-negative Salmonella enterica serovar Typhimurium or the Gram-positive Listeria monocytogenes in mice. We found that at each stage of the viral infection the susceptibility of mice to bacterial super-infections changes dramatically and depends also on whether the secondary infection is a Gram-positive or Gram-negative one. The study shows that the outcome of the secondary infection is determined by a delicate balance between the overproduction of and the hypersensitivity to inflammatory cytokines (TNF-alpha and IFN-gamma), as well as by the changes in blood leukocytes occurring in mice in the course of viral infection.

Animals↗
PubMed2006

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.

Adult↗
PubMed2006

Toll-like receptor-positive cells and recognition of pathogens: how human myeloid dendritic cells respond to in vitro infection with Leishmania infantum.

Dendritic cells (DCs), instructed by the priming signals from microbial factors, can produce interleukin (IL)-12p70 and promote T helper (Th)1 proliferation and interferon (IFN)-gamma production. This event seems to be critical for the containment of infections caused by intracellular pathogens, even including Leishmania infection. In the present in vitro study we have investigated: 1) phagocytic capacities and IL-12 production by human monocyte-derived DCs and macrophages (MØs), infected with Leishmania infantum promastigotes; 2) IFN-gamma production by human CD4+ T cells co-incubated with DCs or macrophages pulsed with live promastigotes. Monocyte-derived myeloid DCs and MØs from healthy donors were infected with live metacyclic Leishmania infantum (MON-1) promastigotes, previously opsonized with 5% autologous serum, at 1:4 cell/parasite ratio. Percentage and index of phagocytosis were calculated after 2, 24 and 48 h of incubation. IL-12 production was evaluated by an ELISA in supernatants from 48 h Leishmania-infected or lipopolysaccharides (LPS)-stimulated DCs and MØs, also in the presence of phytohemagglutinin-activated or inactivated CD4+ T cells. For IFN-gamma production, CD4+ T cells were repeatedly stimulated with DCs or MØs, pulsed with live Leishmania promastigotes or activated with LPS. The number of IFN-gamma-secreting cells was evaluated by an ELISpot assay. Results showed that MØs have a higher phagocytic capacity towards L. infantum promastigotes than DCs. Moreover, unlike MØs, Leishmania-infected DCs were able to release IL-12p70; this production significantly increased in the presence of activated CD4+ T cells. Finally, DCs pulsed with live parasites and added to autologous CD4+ T cells induced a higher number of IFN-gamma-secreting cells than MØs, thus indicating their ability to polarize Th cells toward the Th1 subset. These data indicate that DCs are able to promote protective Th1 immune responses in our experimental model of Leishmania infantum infection, thus representing the grounds for initiating immunoterapeutic and vaccinal strategies.

Animals↗
PubMed2006

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.

Dendritic Cells↗
PubMed2006

In vitro infection of human monocyte-derived dendritic cells with Candida albicans: receptorial involvement and therapeutic implications.

Nowadays, infections with Candida albicans (C.a.) are very frequent, mostly in the so-called immunocompromised host. Therefore, research has been focused on the types of immune response elicited by C.a., with the aim to develop novel therapeutic strategies. Neutrophils and macrophages (MØ) are deeply involved in the host defense against C.a., and also dendritic cells (DCs) seem to be very active in the host protection. In particular, DCs display an array of surface receptors able to interact with fungal components, even including Toll-like receptors. Here, we will illustrate the in vitro immune response of human monocyte-derived DCs infected with C.a. In this test system, DCs exert phagocytic and killing activities with a magnitude similar to that of MØ. Moreover, in the presence of autologous CD4(+) cells, DCs produce T-helper (h) 1 type cytokines. This Th1 polarizing activity is mediated by interleukin-12 released by infected CDs in the presence of CD4(+) cells. Taken together, these data suggest a protective role played by DCs in the course of C.a. infection and the possibility to develop new strategies of immune intervention.

Candida albicans↗
PubMed2005

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.

Fatigue Syndrome, Chronic↗
PubMed2003

Differential contribution of Toll-like receptors 4 and 2 to the cytokine response to Salmonella enterica serovar Typhimurium and Staphylococcus aureus in mice.

The contribution of murine Toll-like receptors 2 and 4 (TLR2 and -4, respectively) to cytokine induction by heat-killed bacteria was analyzed in vitro and in vivo. Gram-negative bacteria induced cytokines primarily via TLR4; the contribution of TLR2 was only minor. Neither TLR4 nor, surprisingly, TLR2 was required in the MyD88-dependent response to Staphylococcus aureus.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Therapeutic manipulation of the immune system: enhancement of innate and adaptive mucosal immunity.

The mucosal immune system has evolved alongside, but separate, from the general systemic immune system. As a major consequence of this dichotomy, only immune responses initiated in mucosal inductive sites can result in effective immunity in mucosal tissues themselves. Oral tolerance, as usually assessed as orally-induced systemic unresponsiveness, contributes to mucosal homoeostasis by preventing unwanted immune reactions to food or environmental antigens. It is now established that tolerance can also be induced by the nasal route and mucosally-induced tolerance is being actively investigated for immune therapy against a number of diseases. Nontoxic derivatives of cholera toxin and the heat labile toxin of Escherichia coli as well as chimeric enterotoxins have been developed. These molecules retain the mucosal adjuvant activity of native enterotoxins and are effective at inducing targeted Th1 or Th2- type immune responses. Mucosal delivery of cytokines as adjuvants represents a safer alternative to parenteral cytokine injection. Nasally administered cytokines such as IL-1 and IL-12 or chemokines including RANTES, lymphotactin, MIP-1 beta, all act as mucosal adjuvants for co-administered antigens. Each of these cytokines promote specific pattern of CD4(+) T helper cell cytokine responses that could be exploited for targeted immune therapy. Although GALT and NALT are both parts of the Common Mucosal Immune System, there are major differences between orally and nasally induced immune responses. Nasal vaccines more effectively promote protective immunity in the genitourinary tract than do oral vaccines. In addition, aging affects mucosal tolerance or immunity in GALT more than is seen in NALT. Therapeutic manipulation of mucosal immunity involves regulation of CD4(+) T cell cytokine responses and thus, should require a careful examination of the host status, including the occurrence of inflammatory bowel diseases.

Adjuvants, Immunologic↗
PubMed2002

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.

Adenocarcinoma↗
PubMed2002

A comparative study between conventional and laparoscopic cholecystectomy: evaluation of phagocytic and T-cell-mediated antibacterial activities.

Over the past few years, many reports have pointed out that open, but not minimally invasive, cholecystectomy was associated with reduced immune functions. Also, after laparoscopic surgery, a reduced impairment of T cell functions and lower levels of proinflammatory cytokines, epinephrine, and norepinephrine were found in comparison with those detected in patients who underwent conventional cholecystectomy. We investigated polymorphonuclear cell- and monocyte-mediated phagocytosis and killing and T-cell-mediated antibacterial activity in 12 patients who underwent open cholecystectomy versus another group of 12 patients who underwent laparoscopic cholecystectomy. Our data show that polymorphonuclear and monocyte killing activities are preserved or are less affected in patients who undergo laparoscopy when compared with patients who undergo conventional operation. On the other hand, in both groups of patients, T-cell-mediated antibacterial activity was significantly reduced in the preoperative period, and, therefore, we could not draw conclusions on the effects of the surgical techniques used on the above immune parameter. The overall data suggest that laparoscopic cholecystectomy is a valid alternative to open surgery because of the moderate postoperative immune suppression and decreased risk of postsurgical infections.

Adult↗
PubMed2002

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.

Antibodies, Monoclonal↗
PubMedDate not supplied

Postsplenectomy immunodepression and its implications: an underestimated problem.

The most important sequelae of splenectomy is immunity depression. This study, conducted in three phases, was aimed at confirming this clinical condition. Data from our phase 1 study clearly show that patients undergoing splenectomy for trauma are in a critical condition because of a latent immunodeficiency shown by skin tests (ST) and in vitro evaluation of the aspecific immune activity. Because the in vitro study of the unspecific immunity that we used seems to be more expensive and complicated than ST, the aim of the phase 2 study was to compare the efficacy and the limits of the two assays (ST versus in vitro study) in detecting the immunodeficiency status of the splenectomized patient. The aim of the phase 3 study was to ascertain whether postsplenectomy immunodeficiency could be a consequence of an altered equilibrium between the lymphocyte subpopulations T helper (Th)1/Th2, evaluated by serum dosage of interferon-gamma and interleukin-4.

Adolescent↗