The gene-immune-behavioral pathway: Gamma-interferon (IFN-γ) simultaneously coordinates susceptibility to infectious disease and harm avoidance behaviors.

Cytokine gene variants are known to influence both infectious disease susceptibility and harm-avoidant behaviors, suggesting that these risk variants may be pleiotropically linked to instinctual disease-avoidant traits. The gamma-interferon (IFNG) +874 T>A polymorphism (rs2430561) is an ideal candidate gene variant for immune-behavioral studies. It is a functional SNP, regulating IFNG mRNA expression; it is known to modulate serotonergic activity and is therefore capable of modifying behavior; and it has previously been associated with increased susceptibility to malaria, tuberculosis, leprosy and Chagas disease. We hypothesized that the infectious disease-high-risk IFNG +874 A-allele would be associated with four personality traits previously reported as behavioral defenses against infection: Harm Avoidance (HA), Extraversion (E), Exploratory Excitability (Exp E), and Openness to Experience (O). We tested this hypothesis in a sample of 168 healthy university students from Southern California genotyped for IFNG +874 T>A and evaluated by the Temperament and Character Inventory-Revised (TCI-R) and the NEO Five-Factor Inventory (NEO-FFI). We found that the infectious disease-high-risk IFNG +874 A-allele was associated with increased HA (P=0.001) and decreased E (P=0.030) and Exp E (P=0.030). These findings suggest that the IFNG +874 A gene variant is linked both to infectious disease susceptibility and to proactive behavioral defenses that reduce infection risk in healthy subjects.

Immunotherapeutic efficacy of Mycobacterium indicus pranii in eliciting anti-tumor T cell responses: critical roles of IFNγ.

Mycobacterium indicus pranii (MIP) is approved for use as an adjuvant (Immuvac/Cadi-05) in the treatment of leprosy. In addition, its efficacy is being investigated in clinical trials on patients with tuberculosis and different tumors. To evaluate and delineate the mechanisms by which autoclaved MIP enhances anti-tumor responses, the growth of solid tumors consisting of Sp2/0 (myeloma) and EL4 (thymoma) cells was studied in BALB/c and C57BL/6 mice, respectively. Treatment of mice with a single intra-dermal (i.d.) injection of MIP 3 days after Sp2/0 implantation greatly suppresses tumor growth. MIP treatment of tumor bearing mice lowers Interleukin (IL)6 but increases IL12p70 and IFNγ amounts in sera. Also, increase in CD8(+) T cell mediated lysis of specific tumor targets and production of high amounts of IL2 and IFNγ by CD4(+) T cells upon stimulation with specific tumor antigens in MIP treated mice is observed. Furthermore, MIP is also effective in reducing the growth of EL4 tumors; however, this efficacy is reduced in Ifnγ(-/-) mice. In fact, several MIP mediated anti-tumor responses are greatly abrogated in Ifnγ(-/-) mice: increase in serum Interleukin (IL)12p70 amounts, induction of IL2 and lysis of EL4 targets by splenocytes upon stimulation with specific tumor antigens. Interestingly, tumor-induced increase in serum IL12p70 and IFNγ and reduction in growth of Sp2/0 and EL4 tumors by MIP are not observed in nonobese diabetic severe combined immunodeficiency mice. Overall, our study clearly demonstrates the importance of a functional immune network, in particular endogenous CD4(+) and CD8(+) T cells and IFNγ, in mediating the anti-tumor responses by MIP.

Why does tuberculosis lead to specific inflammation?

When Mycobacterium tuberculosis infects humans, about 20% of those infected actually develop tuberculosis (TB). In Japan, the incidence of TB in 2008 was 24,760 cases (19.4/100,000 persons) and the rate has been decreasing gradually, but is still higher than in the USA, Holland, and Belgium, for example. Histologically, tuberculosis displays exudative inflammation, proliferative inflammation and productive inflammation depending on the time course. In productive inflammation, granulomatous lesions with necrotic centers are formed. The typical granulomas consist of epithelioid macrophages, Langhans' multinucleated giant cells, lymphocytes and fibroblasts, and the process of their formation involves many cytokines, chemokines and transcription factors. These findings have been derived primarily from animal experiments utilizing an airborne infection apparatus. The conditions for airborne infection have been described in detail elsewhere. This mini-review focuses on what has been found through animal experiments, and also indicates areas for which data are not currently available.

Signaling lymphocytic activation molecule expression and regulation in human intracellular infection correlate with Th1 cytokine patterns.

Induction of Th1 cytokines, those associated with cell-mediated immunity, is critical for host defense against infection by intracellular pathogens, including mycobacteria. Signaling lymphocytic activation molecule (SLAM, CD150) is a transmembrane protein expressed on lymphocytes that promotes T cell proliferation and IFN-gamma production. The expression and role of SLAM in human infectious disease were investigated using leprosy as a model. We found that SLAM mRNA and protein were more strongly expressed in skin lesions of tuberculoid patients, those with measurable CMI to the pathogen, Mycobacterium leprae, compared with lepromatous patients, who have weak CMI against M. leprae. Peripheral blood T cells from tuberculoid patients showed a striking increase in the level of SLAM expression after stimulation with M. leprae, whereas the expression of SLAM on T cells from lepromatous patients show little change by M. leprae stimulation. Engagement of SLAM by an agonistic mAb up-regulated IFN-gamma production from tuberculoid patients and slightly increased the levels of IFN-gamma in lepromatous patients. In addition, IFN-gamma augmented SLAM expression on M. leprae-stimulated peripheral blood T cells from leprosy patients. Signaling through SLAM after IFN-gamma treatment of Ag-stimulated cells enhanced IFN-gamma production in lepromatous patients to the levels of tuberculoid patients. Our data suggest that the local release of IFN-gamma by M. leprae-activated T cells in tuberculoid leprosy lesions leads to up-regulation of SLAM expression. Ligation of SLAM augments IFN-gamma production in the local microenvironment, creating a positive feedback loop. Failure of T cells from lepromatous leprosy patients to produce IFN-gamma in response to M. leprae contributes to reduced expression of SLAM. Therefore, the activation of SLAM may promote the cell-mediated immune response to intracellular bacterial pathogens.

Lysis of autologous macrophages pulsed with hsp10 from Mycobacterium leprae is associated to the absence of bacilli in leprosy.

Peripheral blood mononuclear cells from leprosy patients and normal individuals were analysed for their ability to lyse autologous macrophages pulsed with the Mycobacterium leprae 10 kDa heat shock protein (hsp10), an antigen considered to have an important role in the protective responses in leprosy. Strong cytotoxic responses, with an involvement of gammadelta T and class-I and class-II restricted alphabeta T cells and/or CD16+56+ cells, were observed in normal individuals, paucibacillary (PB) and those multibacillary (MB) patients with undetectable bacillary load. On the contrary, only a weak class-II restricted cytotoxic response was observed in those MB patients with positive bacillary load (MB(+)). Simultaneous addition of IFNgamma plus TNFalpha and IL-12 during hsp10 stimulation could partially upregulate the low cytotoxic response observed in MB(+) by enhancing class-II restricted T cell activity and by development of gammadelta T and/or CD16+56+ cell activity. Our results suggest that the ability to mount an effective cytotoxic response against hsp10-pulsed macrophages in leprosy patients is closely related to the patient's bacterial load and not to the clinical form of the disease.

Interleukin-12 amplifies the M. leprae hsp65-cytotoxic response in the presence of tumour necrosis factor-alpha and interferon-gamma generating CD56+ effector cells: interleukin-4 downregulates this effect.

Interleukin-12 (IL-12) is a major immunomodulatory cytokine that represents a functional bridge between the early resistance and the subsequent antigen specific adaptive immunity. TNF-alpha and IFN-gamma have an important role in the generation of hsp65 specific cytotoxic T lymphocytes (CTL) that lyse hsp65-pulsed autologous macrophages (hsp65 CTL). Since a positive feedback mechanism between TNF-alpha, IFN-gamma and IL-12 has been described, we undertook to evaluate the role of IL-12 on the hsp65 CTL generation in leprosy patients. Our results show that the presence of IL-12 during the first 24 h of the in vitro antigen stimulation amplifies the hsp65 cytotoxic response whenever both IFN-gamma and TNF-alpha are present. The addition of these three cytokines (CKs) was able to abrogate the inhibitory effect of IL-10 on hsp65 CTL in cells from paucibacillary patients (PB) but not that of IL-4 in PB and normal controls (N). Both IL-12 or anti IL-4 enhanced the cytotoxic activity in cells from multibacillary patients (MB). Anti IL-4 upregulated the binding of IFN-gamma and did not modify that of TNF-alpha so the low CTL activity could be as a result of IL-4 by a decrease of the IFN-gamma binding on MB cells. Cells from those MB patients taking thalidomide (MB-T) did neither bind IFN-gamma nor TNF-alpha even when antigen or anti-IL-4 were added, demonstrating that thalidomide inhibits either the in vitro binding or receptor expression of both TNF-alpha and IFN-gamma. Development of CD56 effector cells during the hsp65 stimulation was observed in PB and N by the addition of IL-12 plus TNF-alpha and IFN-gamma, while in MB and MB-T anti IL-4 was also required. So, the inhibitory effect of IL-4 on either production of IFN-gamma, TNF-alpha and/or IL-12 or their receptors could be the mechanism underlying the lack of the hsp65 CTL generation in cells from MB.

CD1-restricted T-cells influence IgG subclass and IgE production.

BACKGROUND: Human CD1 has recently emerged as a third family of antigen-presenting molecules that is distinct from either major histocompatibility complex class I or class II. OBJECTIVE: We investigated whether the CD1b-restricted T-cell interaction with antigen alters human IgG subclass and IgE isotype production. METHODS: CD1b-restricted antigen-specific T cells derived from the skin lesion of a patient with leprosy were stimulated with their cognate antigen, lipoarabinomman (LAM) of Mycobacterium leprae, in the presence of CD1+ antigen-presenting cells and tested for their ability to alter IgG subclass and IgE production from IgD+ B cells. RESULTS: CD1-restricted T cells cultured with CD1+ antigen-presenting cells in the absence of LAM induced IgG1, IgG3, IgG4, and IgE, whereas CD1b-restricted T cells cultured in the presence of LAM induced IgG1 and IgG3 and inhibited production of IgG4 and IgE. Production of IgG4 and IgE was rescued in the CD1-restricted system by the addition of anti-interferon-gamma. IgG2 production was not induced under any circumstances. CONCLUSION: In this study we demonstrated that a specific CD1b-restricted T-cell line can behave similarly to classically-restricted Th1-type T cells. CD1b-restricted T-cells of this type may regulate immune responses to microbial pathogens by simultaneously enhancing cell-mediated immunity and downregulating IgG4 and IgE responses.

New vaccines against tuberculosis.

It has proved difficult to vaccinate effectively against tuberculosis with mycobacterial components or even with whole dead mycobacteria; protection was always inferior to that obtained with the live attenuated vaccine known as bacillus Calmette-Guérin (BCG). We have found that this may no longer be the case. Expression of the gene for a single mycobacterial antigen (Mycobacterium leprae hsp65) in adult BALB/c mice resulted in substantial cell-mediated protection against challenge with M. tuberculosis, but only when it was generated as an endogenous antigen within antigen-presenting cells. CD4 and CD8 T cells cloned from spleens of immunized mice passively transferred protection to non-immunized mice, and CD8 cells selectively lysed macrophages infected with M. tuberculosis. The ability of the clones to protect recipient mice against challenge infection was most strongly associated with specific cytotoxic capacity and secondarily with IFN-gamma production. Three modes of expressing the gene have been tested: a) expression from a retroviral vector (pZIPNeoSV) in implanted J774 tumor cells, b) expression from the same vector via bone marrow cells transfected in vitro and used to reconstitute irradiated mice, and c) in a preliminary experiment, from cytomegalovirus (CMV) immediate-early and hydroxymethylglutaryl Co-A reductase promoters injected as plasmid DNA into muscle.

New vaccines against tuberculosis

It has proved difficult to vaccinate effectively against tuberculosis with mycobacterial components or even with whole dead mycobacteria;protection was always inferior to that obtained with the live attenuated vaccine known as bacillus Calmette-Guérin (BCG). We have found that this may no longer be the case. Expression of the gene for a single mycobacterial antigen (Mycobacterium leprae hsp 65) in adult BALB/c mice resulted in substantial cell-mediated protection agains challenge with M. tuberculosis, but only when it was generated as an endogenous antigen within antigen-presenting cells. CD4 and CD8 T cells cloned from spleens of immunized mice passively transferred protection to non-immunized mice, and CD8 cells selectively lysed macrophages infected with M. tuberculosis. The ability of the clones to protect recipient mice against challenge infection was most strongly associated with specific cytotoxic capacity and secondarily with IFN-gamma production. Three modes of expressing the gene have been tested: a)expression froma retroviral vector (pZIPNeoSV) in implanted J774 tumor cells, b)expression from the same vector via bone marrow cells transfected in vitro and used to reconstitute irradiated mice, and c)in a preliminary experiment, from cytomegalovirus (CMV) immediate-early and hydroxymethylglutaryl Co-A reductase promotors injected as plasmid DNA into muscle.

[Biological properties and clinical applications of interferon gamma (IFN-gamma)]. / Wlasciwosci biologiczne i kliniczne zastosowanie interferonu gamma (IFN-gamma).

Interferon-gamma (IFN-gamma) is produced by activated T cells and probably by NK cells. Its production can be induced by mitogens, antigens and other molecules. IFN-gamma interacts with cells by binding to specific membrane receptors. IFN-gamma--1b is an Escherichia coli--derived recombinant DNA product, which has biological activity identical to natural human IFN-gamma. This IFN type is a more potent immunomodulator than IFN-alpha and IFN-beta. Long term treatment with a therapeutic dosage of IFN-gamma--1b produces a significant reduction in the incidence of serious infections in patients with chronic granulomatous disease. This cytokine can be also useful in the treatment of patients with visceral leishmaniasis, Epstein-Barr virus infections, lepromatous leprosy and other infectious diseases. Phase I and II studies have demonstrated it to be capable of producing antitumor effects, especially in metastatic renal cell carcinoma and some hematologic malignancies. Clinical trials have suggested efficacy of IFN-gamma in the treatment of severe atopic dermatitis and rheumatoid arthritis. The most common adverse reactions are fever, headaches and erythema at the injection site.

T-cell stimulation with purified mycobacterial antigens in patients and healthy subjects infected with Mycobacterium leprae: secreted antigen 85 is another immunodominant antigen.

Peripheral blood leucocytes from 9 paucibacillary and 12 multibacillary leprosy patients, from 18 healthy controls and from 34 healthy leprosy contacts were stimulated with three mycobacterial heat shock proteins with respective molecular weights of 70, 65 and 18 kDa and with the secreted 30-32 kDa protein, also called antigen 85. Antigen 85 was found to be the most powerful T-cell antigen (as measured by lymphoproliferation and IFN-gamma secretion), eliciting a positive response in all (100%) paucibacillary patients and in all lepromin-positive controls and contacts. The three heat shock proteins (hsp) were less active T-cell stimuli. Reactivity to the 70 kDa hsp was found in only 44% of the paucibacillary patients, in 80% of the lepromin-positive controls and in 60% of the lepromin-positive leprosy contacts. The 65 kDa hsp stimulated T cells in 89% of the paucibacillary patients and in 80% of the lepromin-positive controls and contacts. Responsiveness to the 18 kDa hsp, finally, was clearly more frequent in tuberculoid leprosy patients (78%) than in lepromin-positive controls (40%) or lepromin-positive leprosy contacts (4%). T-cell reactivity of 8 lepromin-negative controls, of 9 lepromin-negative contacts and of 12 multibacillary leprosy patients was low to all the antigens tested. Although proliferative and IFN-gamma responses were generally closely related, some subjects demonstrated a dissociation of these two immune parameters. Our data confirm previous findings on the powerful T-cell stimulatory properties of antigen 85 during M. leprae infection and suggest that this antigen is indeed a potentially protective T-cell immunogen.

Defining protective responses to pathogens: cytokine profiles in leprosy lesions.

The immunological mechanisms required to engender resistance have been defined in few infectious diseases of man, and the role of specific cytokines is unclear. Leprosy presents clinically as a spectrum in which resistance correlates with cell-mediated immunity to the pathogen. To assess in situ cytokine patterns, messenger RNA extracted from leprosy skin biopsy specimens was amplified by the polymerase chain reaction with 14 cytokine-specific primers. In lesions of the resistant form of the disease, messenger RNAs coding for interleukin-2 and interferon-gamma were most evident. In contrast, messenger RNAs for interleukin-4, interleukin-5, and interleukin-10 predominated in the multibacillary form. Thus, resistance and susceptibility were correlated with distinct patterns of cytokine production.

Recombinant interferon-gamma (rIFN-gamma) in dermatology.

This paper gives a short review on the function, pharmacokinetics, and therapeutic application of recombinant interferon-gamma (rIFN-gamma) in dermatology. Simultaneously, our own experiences are presented for 57 patients (phase II study) suffering from genital warts (21 patients), psoriatic arthritis (10 patients), psoriasis vulgaris (three patients), malignant melanoma (six patients), bowenoid papulosis (four patients), Behcet's disease (four patients), basal cell carcinoma (six patients), as well as herpes simplex recidivans, epidermodysplasia verruciformis, and mycosis fungoides (one patient each). We conclude that there might be an indication for treatment with rIFN-gamma in genital warts, bowenoid papulosis, Behcet's disease, and microbial infections, such as leprosy and cutaneous leishmaniasis. Even though there are reports of a limited beneficial effect of rIFN-gamma on arthritis and skin lesions in psoriasis, we failed to observe any in 10 patients. The main side effects in our low-dose study (50-100 micrograms/d) were mild fever (78%), fatigue (78%), and myalgia (65%). Laboratory tests revealed an increase in the serum triglyceride level, in particular, in psoriatic patients.

Inhibition of interferon-gamma-mediated activation in mouse macrophages treated with lipoarabinomannan.

Lipoarabinomannan (LAM), purified from the cell walls of Mycobacterium leprae and M. tuberculosis, is a potent inhibitor of interferon-gamma (IFN-gamma) mediated activation of macrophages. The capability of LAM to inhibit IFN-gamma activation of macrophages in vitro was dose dependent and required a 24-h pre-exposure. Defective activation was evident as a block in IFN-gamma-induced cytocidal activity for tumour cell targets and microbicidal capacity for intracellular Toxoplasma gondii. Additionally, LAM treatment blocked the induction of surface Ia antigens on peritoneal macrophages by IFN-gamma. The requirement for pretreatment with LAM was further substantiated by the finding that peritoneal macrophages that were activated in vivo were not affected by LAM treatments and retained full microbicidal function. However, once inhibited by LAM treatment in vitro, macrophages remained fully refractory to IFN-gamma activation for up to 5 days in culture. Inhibition of IFN-gamma activation in macrophages treated with LAM was not overcome by 100-fold increases in the dose of IFN-gamma used or by a constant dose of IFN-gamma in combination with 100-fold increases in the level of endotoxin used to trigger cytotoxic activity. The defect in IFN-gamma unresponsiveness was not due to altered receptor function, as control and LAM-treated macrophages showed similar capacity to bind, internalize, and digest radiolabelled IFN-gamma. Based on the in vitro findings reported here, the inhibition of IFN-gamma-mediated macrophage activation by exposure to LAM may contribute to defective macrophage function observed in lepromatous granulomas and thus constitutes an important aspect of pathogenesis in mycobacterioses.

[Macrophage activation and Mycobacterium leprae: effect of interferon gamma on the production of oxygen free radicals by phagocytic cells]. / Activation macrophagique et Mycobacterium leprae: action de l'interféron gamma sur la production de radicaux oxygénés libres (R.O.L.) des cellules phagocytaires.

Activation of the respiratory metabolic channel (F.O.R.), responsible in part for the bactericidal effect, was measured in vitro by a chemoluminescence test on circulating phagocytes. All mycobacteria tested, except for Mycobacterium leprae, induced a significant response. Its effect on lepromatous leprosy pathology is a subject for discussion.

Interferon-gamma, the activated macrophage, and host defense against microbial challenge.

Recent research on human macrophage activation has reemphasized the critical role of the lymphokine-secreting T cell in converting quiescent macrophages to efficient microbicidal phagocytes. Interferon-gamma, a key lymphokine secreted by antigen-triggered T4+ helper cells, is capable of inducing the macrophage to act against a diverse group of microbial targets, in particular, intracellular pathogens. In animal models, treatment with recombinant interferon-gamma is beneficial in systemic intracellular infections, and inhibition of endogenous interferon-gamma activity impairs host resistance. Trials in patients with cancer, leprosy, and the acquired immunodeficiency syndrome (AIDS) have shown that interferon-gamma can activate the mononuclear phagocyte in humans. This research and the identification of patients whose T cells fail to produce interferon-gamma properly has set the stage for evaluating the role of macrophage-activating immunotherapy using interferon-gamma in various human infectious diseases.