Interferon-gamma mRNA Expression Research Articles

Differential spontaneous expression of mRNA for IL-4, IL-10, IL-13, IL-2 and interferon-gamma (IFN-gamma) in peripheral blood mononuclear cells (PBMC) from atopic patients.

Distinct cytokine-producing T cell subsets are well known to play a major role in IgE production and to be differentially regulated in allergic patients, although the characterization of the type 1/type 2 cytokine pattern in PBMC during allergic responses remains to be clearly defined. The aim of this study was to determine whether different cytokine profiles are observed directly in PBMC of atopic donors. We attempted to study several cytokines (IL-2, IFN-gamma, IL-4, IL-10 and IL-13) using not only ELISA but also polymerase chain reaction (PCR) techniques, because the frequency of cytokine-producing cells in peripheral blood is very low. All the patients were selected during their acute symptomatologic phase. Data showed a significantly higher production of IL-4 (P = 0.05) and IL-10 (P < 0.005) as determined by ELISA in phytohaemagglutinin (PHA)/phorbol myristate acetate (PMA)-stimulated mononuclear cells of atopic donors compared with controls, although spontaneous IL-4 production without stimulation was never detected within either atopic or control groups. The reverse-transcriptase (RT)-PCR technique appeared to be advantageous in that it allowed the detection of the spontaneous expression of cytokine mRNA in cells without stimulation. We found a clear expression of IL-4 mRNA spontaneously in all atopic patients, whereas normal donors in most cases did not show specific signals (P < 0.0001). Less differences between atopic subjects and controls were found in IL-10 mRNA expression. Although the technique of RT-PCR amplification used in this study is semiquantitative, a reproducible and significant (P < 0.001) enhancement of IL-10 mRNA expression was observed in atopic donors. A heterogeneous expression of IL-13 mRNA was observed in individuals from the two groups studied, although mean levels in atopic donors were slightly enhanced compared with controls (P = 0.02). Furthermore, we did not observe any alteration in the expression of the type 1-derived cytokines such as IFN-gamma and IL-2. In addition, we showed a lack of correlation between the expression of serum IgE (total or specific) and spontaneous IL-4 mRNA expression. This study showed a tendency of PBMC from atopic donors to express a type 2-like cytokine pattern, with IL-4 as the most discriminatory cytokine. Additionally, as the level of serum IgE has a low predictive value in allergic disease, and as the elevated expression of IL-4 that we found was not correlated with serum IgE, we could strongly suggest that the measurement of IL-4 in blood mononuclear cells may be of great value in the analysis of allergic responses in atopic donors.

Analysis of rearranged T cell receptor (TCR) V beta transcripts in livers of primary biliary cirrhosis: preferential V beta usage suggests antigen-driven selection.

The presence of autoantibodies to mitochondrial pyruvate dehydrogenase complex-E2 (PDC-E2) and self-reactive T cells to PDC suggests that autoimmune mechanisms may be involved in the pathogenesis of primary biliary cirrhosis (PBC). Molecular analysis of intrahepatic TCR repertoire may provide valuable information on a T cell mechanism for PBC immunopathogenesis. We therefore analysed the TCR V beta usage in different regions of the livers removed during transplantation from two PBC patients. Using reverse transcription and polymerase chain reaction (RT-PCR), a limited heterogeneity of rearranged TCR V beta transcripts was demonstrated in different locations of the same liver. Sequence analysis of V beta-D beta-J beta (CDR3: the third complementarity determining region) showed the presence of conserved residues, no random N additions, and a common motif within CDR3. These results suggest that T cells homing to PBC liver may be antigen-driven. To elucidate further whether an immune deviation related to T helper 1 cell (Th1) or Th2 responses may exist in PBC, intrahepatic mRNA expression of IL-2, IL-4 and interferon-gamma (IFN-gamma) was examined by the RT-PCR method. IL-2 and IFN-gamma could be amplified, whereas IL-4 was virtually undetectable in the livers from the two patients with PBC. The findings suggest that polarization of intrahepatic lymphokine expression toward the Th1-dominant pattern may be significant in the immunopathogenesis of PBC.

A non-protective T helper 1 response against the intra-macrophage protozoan Theileria annulata.

Theileria annulata is a protozoan parasite which infects and transforms bovine macrophages. Infected macrophages possess augmented antigen presentation capabilities, as they are able to activate the majority of T cells from unexposed animals. In vivo, T cells in the draining lymph node (principal site of parasite development) are activated 'non-specifically' by the parasite. This event is followed by failure of the immune response to control the infection. Protective immune responses against intra-macrophage protozoa are usually mediated by T helper 1 (Th1) T cell responses. Here we examine the cytokine responses made by T. annulata-activated T cells. We show that the outcome of in vitro activation of T cells by parasitized macrophages is a skewing of their cytokine responses towards preferential expression of interferon-gamma (IFN-gamma) mRNA. The in vitro response is mirrored during in vivo infection, as greatly elevated amounts of IFN-gamma protein are found in lymph efferent from infected lymph nodes, while expression of IL-4 mRNA within the node stops. IFN-gamma production does not correlate with protection against the parasite, as infected cells flourish during peak IFN-gamma production, and only very small amounts of IFN-gamma are produced during the effective immune response of an immunized animal. Overproduction of IFN-gamma and loss of IL-4 expression are also likely to account for the failure of B cells to reach the light zone of germinal centres, a developmental step which is tightly regulated by cytokines.

Amelioration of collagen II-induced arthritis in rats by the type IV phosphodiesterase inhibitor Rolipram.

The effect of Rolipram, a selective inhibitor of the cyclic AMP specific phosphodiesterase (PDE IV) was evaluated in the rat collagen type II (RCII)-induced arthritis model in the DA rat. Rolipram was given either shortly before expected onset of disease (days 10-14) or shortly after the onset of clinically evident arthritis (days 15-19 after immunization). Administration at days 10-14 delayed the onset of arthritis for approximately 5 days, but the severity of arthritis was thereafter comparable to that seen in a non-treated control group. Rolipram treatment of animals with manifest arthritis inhibited further arthritis development and also tended to diminish its severity at a phase of disease where non-treated control animals showed a rapidly progressing disease development. Serum levels of antibodies to RCII were in all experiments similar between Rolipram-treated and control animals. An in situ hybridization method for determining cytokine mRNA synthesis in regional lymph nodes, after administration of Rolipram (at days 2-7), demonstrated a strong inhibitory effect on tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) mRNA expression, whereas no effects were seen on IL-2 mRNA synthesis after in vivo challenge with native RCII emulsified in Freund's incomplete adjuvant. The results thus demonstrate strong preventive as well as therapeutic effects of Rolipram in a model for arthritis that is very similar to human rheumatoid arthritis with respect to cytokine regulation, and suggest that Rolipram has its major effects in the effector stage of the arthritogenic immune response.

Cellular mRNA expression of interferon-gamma (IFN-gamma), IL-4 and IL-10 relates to resistance to experimental autoimmune myasthenia gravis (EAMG) in young Lewis rats.

Age-related alterations in the immune system, including changes in lymphocyte subset composition, result in changes of cytokine patterns and might thereby influence the incidence and severity of autoimmune diseases. To investigate the age-related resistance to EAMG, an animal model for human MG, young (4-week-old) and adult (8-10-week-old) female Lewis rats were immunized with Torpedo acetylcholine receptor (AChR) and Freund's complete adjuvant (FCA). Adult Lewis rats showed severe weight loss and progressive muscular weakness after immunization, while young rats developed minor clinical signs of EAMG after a prolonged interval post-immunization. By comparison with adult rats, the young had lower AChR-specific T and B cells responses, and less muscle AChR loss. In situ hybridization performed on mononuclear cells (MNC) from lymph nodes revealed that young rats had lower levels of AChR-specific IFN-gamma, IL-4 and IL-10 mRNA-expressing cells compared with adult rats. Since IFN-gamma, IL-4 and IL-10 promote the development of EAMG, the low expression of these cytokines might contribute to EAMG resistance in young Lewis rats.

Cellular mRNA expression of interferon-gamma (IFN-gamma), IL-4 and transforming growth factor-beta (TGF-beta) in rats nasally tolerized against experimental autoimmune myasthenia gravis (EAMG).

Nasal administration of nicotinic acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with AChR plus Freund's complete adjuvant (FCA) resulted in prevention or marked decrease of the severity of EAMG, suppression of AChR-specific B cell responses and of AChR-reactive T cell functions. To examine the involvement of immunoregulatory cytokines and the underlying mechanisms involved in tolerance induction, in situ hybridization with radio-labelled synthetic oligonucleotide probes was adopted to enumerate mononuclear cells (MNC) expressing mRNA for the proinflammatory cytokine IFN-gamma, the B cell stimulating IL-4 and the immune response-down-regulating TGF-beta. Popliteal and inguinal lymph nodes from EAMG rats contained elevated numbers of AChR-reactive IFN-gamma, IL-4 and TGF-beta mRNA-expressing cells compared with control rats receiving PBS nasally and injected with FCA only. Nasal tolerance to EAMG was accompanied by decreased numbers of AChR-reactive IFN-gamma and IL-4 mRNA-expressing cells, and strong up-regulation of TGF-beta mRNA-positive cells in lymphoid organs compared with non-tolerized EAMG control rats. The relative affinity of anti-AChR antibodies was lower, but muscle AChR amounts were higher in nasally tolerized rats compared with non-tolerized EAMG control rats. The results suggest that IFN-gamma and IL-4 are central effector molecules in the development of EAMG, and that TGF-beta plays an important role in tolerance induction to EAMG.

Rhodococcus equi secreted antigens are immunogenic and stimulate a type 1 recall response in the lungs of horses immune to R. equi infection.

Rhodococcus equi is an opportunistic pathogen in immunocompromised humans and an important primary pathogen in young horses. Although R. equi infection can produce life-threatening pyogranulomatous pneumonia, most foals develop a protective immune response that lasts throughout life. The antigen targets of this protective response are currently unknown; however, Mycobacterium tuberculosis is a closely related intracellular pathogen and provides a model system. Based on previous studies of M. tuberculosis protective antigens released into culture filtrate supernatant (CFS), a bacterial growth system was developed for obtaining R. equi CFS antigens. Potential immunogens for prevention of equine rhodococcal pneumonia were identified by using immunoblots. The 48-h CFS contained five virulence-associated protein bands that migrated between 12 and 24 kDa and were recognized by sera from R. equi-infected foals and immune adult horses. Notably, the CFS contained the previously characterized proteins VapC, VapD, and VapE, which are encoded by genes on the R. equi virulence plasmid. R. equi CFS was also examined for the ability to stimulate a type 1-like memory response in immune horses. Three adult horses were challenged with virulent R. equi, and cells from the bronchoalveolar lavage fluid were recovered before and 1 week after challenge. In vitro stimulation of pulmonary T-lymphocytes with R. equi CFS resulted in significant proliferation and a significant increase in gamma interferon mRNA expression 1 week after challenge. These results were consistent with a memory effector response in immune adult horses and provide evidence that R. equi CFS proteins are antigen targets in the immunoprotective response against R. equi infection.

The pathogenic roles of tumor necrosis factor receptor p55 in acetaminophen-induced liver injury in mice.

Acetaminophen (APAP) causes a massive production of intrahepatic tumor necrosis factor alpha (TNF-alpha). However, it still remains elusive regarding the roles of TNF-alpha in APAP-induced liver injury. Hence, we examined pathogenic roles of the TNF-alpha-TNF receptor with a molecular weight of 55 kDa (TNF-Rp55) axis in APAP-induced hepatotoxicity using TNF-Rp55-deficient [TNF-Rp55-knockout (KO)] mice. When wild-type (WT) BALB/c and TNF-Rp55-KO mice were intraperitoneally injected with a lethal dose of APAP (750 mg/kg), the mortality of TNF-Rp55-KO mice was marginally but significantly reduced compared with WT mice. Upon treatment with a nonlethal dose (600 mg/kg), WT mice exhibited an increase in serum transaminase levels. Histopathologically, centrilobular hepatic necrosis with leukocyte infiltration was evident at 10 and 24 h after APAP challenge. Moreover, mRNA expression of adhesion molecules, several chemokines, interferon-gamma (IFN-gamma), and inducible nitric oxide synthase (iNOS) was enhanced in the liver. On the contrary, serum transaminase elevation and histopathological changes were attenuated in TNF-Rp55-KO mice injected with APAP (600 mg/kg). The gene expression of all molecules except for IFN-gamma and iNOS was significantly attenuated in TNF-Rp55-KO mice. Moreover, anti-TNF-alpha neutralizing antibodies alleviated liver injury when administered at 2 or 8 h after but not at 1 h before APAP challenge to WT mice. Collectively, the TNF-alpha-TNF-Rp55 axis has pathogenic roles in APAP-induced liver failure.

Terfenadine antagonism against interleukin-4-modulated gene expression of T cell cytokines.

Here, we investigated whether an anti-allergy drug, terfenadine, affects interleukin-4-modulated cytokine expression in peripheral T cells. Peripheral blood T cells were first stimulated with recombinant interleukin-4 and then tested for modulation of the mRNA of a panel of cytokines using the reverse transcription-polymerase chain reaction followed by Southern blot analysis. It was found that T cells constitutively expressed mRNA specific to T helper 1 cytokines (interleukin-2, interferon-gamma, tumor necrosis factor-alpha), which was markedly downregulated upon stimulation with interleukin-4, whereas mRNA for T helper 2 cytokines such as interleukins 4, 5, and 6 was induced in response to interleukin-4. Interestingly, the interleukin-4-induced expression of all T helper 2 cytokines examined was markedly downregulated by terfenadine. Among T helper 1 cytokines, interleukin-4-mediated suppression of tumor necrosis factor-alpha was not affected by terfenadine, which, however, markedly restored mRNA expression of interferon-gamma or interleukin-2. Electrophoretic mobility shift assays using [32P]-labeled synthetic oligonucleotides encoding the consensus binding motif of activator protein-1 demonstrated that interleukin-4-induced binding of activator protein-1 composed of JunB was interfered by terfenadine. This study indicates that terfenadine, at least partially, interferes with interleukin-4-activated signaling, leading to terfenadine antagonism against the modulatory impact of interleukin-4 on T cell cytokines.

IL-6 and Crohn's disease.

Interleukin-6 (IL-6) is a pleiotropic cytokine with central roles in immune regulation, inflammation, hematopoiesis, and oncogenesis. Its biological activities are shared by IL-6-family of cytokines such as leukemia inhibitory factor and oncostatin M. When IL-6 binds to IL-6R, the IL-6/IL-6R complex then associates with gp130, the common signal transducer of cytokines related to IL-6. IL-6R does not have to be expressed on the cell surface for IL-6 signaling because soluble form of IL-6R (sIL-6R) can bind to IL-6 and function through gp130. Increased levels of IL-6 and sIL-6R have been demonstrated in both serum and intestinal tissues of the patients with active Crohn's disease. In animal model studies, anti-IL-6R monoclonal antibody (mAb) successfully prevented intestinal inflammation and systemic wasting disease by suppressing adhesion molecule expression by vascular endothelium. It also reduced colonic expression of tumor necrosis factor alpha, IL-1beta, and interferon gamma mRNA without affecting the production of transforming growth factor beta, IL-10, and IL-4. Moreover, the treatment displayed therapeutic efficacy against established colitis through the induction of lamina propria T-cell apoptosis. These results strongly suggest that specific targeting of IL-6/sIL-6R pathway will be a promising new approach for the treatment of Crohn's disease, and the clinical trial of humanized anti-IL-6R mAb has been carried out.

Differential regulation of cytokine gene expression by avian heterophils during receptor-mediated phagocytosis of opsonized and nonopsonized Salmonella enteritidis.

Internalization of pathogens by phagocytic cells triggers the innate immune response, which in turn regulates the acquired response. Phagocytes express a variety of receptors that are involved in recognition of pathogens, including (1) pattern recognition receptors (PRR), which recognize conserved motifs, (2) complement receptors (CR), which recognize complement-opsonized pathogens, and (3) Fc receptors (FcR), which recognize antibody-opsonized pathogens. Recognition of microbes is accompanied by the induction of multiple cell processes, including the production of proinflammatory and anti-inflammatory cytokines and chemokines. The objective of the present experiments was to use probes to known avian proinflammatory and anti-inflammatory cytokines and TaqMan technology to ascertain levels of cytokine gene expression in avian heterophils following receptor-mediated phagocytosis of either nonopsonized Salmonella enteritidis (SE), serum-opsonized SE, or IgG-opsonized SE. Expression of interleukin-6 (IL-6) and IL-8, considered in mammals as a proinflammatory chemokine, were upregulated following exposure to the nonopsonized or the opsonized SE. However, mRNA expression for IL-18 and interferon-gamma (IFN-gamma) was downregulated, and the expression of mRNA for the anti-inflammatory cytokine transforming growth factor-beta4 (TGF-beta 4) was upregulated. Interestingly, IL-1beta mRNA expression was significantly upregulated in heterophils that phagocytized either the nonopsonized SE via PRRs or IgG-opsonized SE via FcRs, whereas serum-opsonized SE phagocytized by CRs induced a downregulation of IL-1beta mRNA. These results suggest that signaling interactions initiated by receptor recognition of the microbe surface differentially regulate the induction of inflammatory cytokines in avian heterophils.

Attenuated Yersinia enterocolitica mutant strains exhibit differential virulence in cytokine-deficient mice: implications for the development of novel live carrier vaccines.

Yersinia enterocolitica mutant strains, including mutants deficient in the chaperone SycH resulting in a functional deficiency in tyrosine phosphatase (YopH), Mn-cofactored superoxide dismutase (SodA), iron-repressive protein 1 (IRP-1), and Yersinia adhesin A (YadA), were demonstrated to be highly attenuated in wild-type C57BL/6 mice. TNFRp55(-/-), IL-12p40(-/-), and IL-18(-/-) mutant mice, in which the Yersinia wild-type strain causes severe systemic infections, were used to investigate whether these Yersinia mutant strains would be attenuated in immunodeficient hosts. A plasmid-cured Yersinia mutant strain was unable to colonize any of the mutant mice tested. A SycH-deficient mutant strain colonized intestinal tissues of these mice but was attenuated for systemic infection in all of the mutant mice. Both YadA- and Irp-1-deficient Yersinia mutants were still attenuated in IL-12(-/-) and IL-18(-/-) mice but were pathogenic in TNFRp55(-/-) mice. By contrast, a Yersinia sodA mutant was highly pathogenic for TNFRp55(-/-) and IL-12p40(-/-) mice while interleukin-18 (IL-18) was dispensable. This finding demonstrates that certain virulence factors enable yersiniae to compete with distinct cytokine-dependent host defense mechanisms. Moreover, while gamma interferon mRNA expression did not reflect protective host responses in cytokine-deficient mice, IL-10 expression coincided with a heavy splenic bacterial load and was associated with progressive infection courses. We can thus segregate minor (SodA), intermediate (YadA and IRP-1), and major (YopH) virulence factors of Y. enterocolitica. Finally, we demonstrate that, even in immunocompromised hosts, Yersinia sycH and, with some restrictions, irp-1 mutants may be suitable for use as live carrier vaccines.

Intrapulmonary expression of macrophage inflammatory protein 1alpha (CCL3) induces neutrophil and NK cell accumulation and stimulates innate immunity in murine bacterial pneumonia.

Macrophage inflammatory protein 1alpha (MIP-1alpha) (CCL3) is an important mediator of leukocyte recruitment and activation in a variety of inflammatory states, including infection. A recombinant human type 5 adenovirus containing the murine MIP-1alpha cDNA (AdMIP-1alpha) was constructed to determine the effect of transient intrapulmonary expression of MIP-1alpha on leukocyte recruitment, activation, and bacterial clearance in a murine model of Klebsiella pneumoniae pneumonia. The intratracheal administration of AdMIP-1alpha resulted in both time- and dose-dependent expression of MIP-1alpha mRNA and protein within the lung. Importantly, the intrapulmonary overexpression of MIP-1alpha resulted in a maximal 35- and 100-fold reduction in lung and blood bacterial burden, respectively, in animals cochallenged with K. pneumoniae, which was associated with a significant increase in neutrophil and activated NK cell accumulation. Furthermore, the transgenic expression of MIP-1alpha during bacterial pneumonia resulted in enhanced expression of gamma interferon mRNA, compared to that observed in Klebsiella-challenged animals pretreated with control vector. These findings indicate an important role for MIP-1alpha in the recruitment and activation of selected leukocyte populations in vivo and identify this cytokine as a potential immunoadjuvant to be employed in the setting of localized bacterial infection.

Involvement of Toll-like receptor 4 signaling in interferon-gamma production and antitumor effect by streptococcal agent OK-432.

The streptococcal agent OK-432 has been used for immunotherapy of head and neck cancer, among other malignancies, but its mechanism of action is unknown. Because the Toll-like receptor 4 (TLR4)/MD-2 complex is important in enabling the mammalian immune system to recognize bacterial components, we investigated whether expression of the TLR4 and MD-2 genes is associated with OK-432-induced anticancer immunity. Peripheral blood mononuclear cells (PBMCs) from 28 patients with head and neck cancer were analyzed for TLR4 and MD-2 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR) analysis. PBMCs were treated in vitro with OK-432 or with OK-PSA (a lipoteichoic-acid-related molecule that is an active component of OK-432), and interferon-gamma (IFN-gamma) mRNA expression, an immune response measure, was analyzed by RT-PCR. Patient sera collected 24 hours after OK-432 administration were examined for IFN-gamma protein using an enzyme-linked immunosorbent assay. Lewis lung carcinoma-bearing wild-type C57BL/6 and TLR4-deficient mice (four mice per group) received intraperitoneal injections of OK-432, and tumor volumes and sera IFN-gamma levels were measured over time. All statistical tests were two-sided. Twenty patients expressed both TLR4 and MD-2. Expression of TLR4 and MD-2 genes was associated with the in vivo IFN-gamma induction in 19 patients administered OK-432 (Fisher's exact test P<.001). Although both OK-432 and OK-PSA induced IFN-gamma expression from PBMCs in vitro, expression of TLR4 and MD-2 was associated only with IFN-gamma expression induced by OK-PSA (P<.001). In vivo intraperitoneal administration of OK-432 resulted in an increase of IFN-gamma in sera from wild-type mice but not in sera from TLR4-deficient mice. Tumors in wild-type mice treated with OK-432 were statistically significantly smaller than those in mice treated with saline (P =.007). By contrast, in TLR4-deficient mice, there was no difference in tumor volume between the two treatment groups. TLR4 and MD-2 may mediate OK-432-induced anticancer immunity.

Anti-interleukin-6 therapy for Crohn's disease.

Proinflammatory cytokines have been demonstrated to play a crucial role in the pathogenesis and physiopathology of various chronic inflammatory conditions including Crohn's disease (CD). Among these cytokines, interleukin-6 (IL-6) must be especially important because increased serum concentrations of acute phase proteins, reduced level of serum albumin, and remarkable thrombocytosis are all well-explained by the increased level of IL-6. Moreover, IL-6 is capable of stimulating even IL-6 receptor (IL-6R) negative cells such as vascular endothelial cells when complexed to soluble form of IL-6R (sIL-6R), and serum level of IL-6 as well as sIL-6R has been demonstrated to increase during inflammation. To investigate the therapeutic potential of IL-6 signaling blockade for CD, anti-IL-6R monoclonal antibody (mAb) was introduced to various murine models of colitis. Anti-IL-6R mAb successfully prevented wasting disease and the development of macroscopic and histological lesions. It suppressed the accumulation of ICAM-1 positive and Mac-1 positive cells in the lamina propria (LP) and the expression of ICAM-1 and VCAM-1 by vascular endothelial cells. Expansion of colonic and splenic CD4(+) T cells was reduced as well as the colonic expression of tumor necrosis factor alpha (TNF-alpha), IL-1beta, and interferon gamma (IFN-gamma) mRNA without affecting the production of transforming growth factor beta (TGF-beta), IL-10, and IL-4 mRNA. The treatment also suppressed established colitis by inducing LP T cell apoptosis. These results strongly suggest that specific targeting of IL-6/sIL-6R pathway will be a promising new approach for the treatment of CD, and the clinical trial of humanized anti-IL-6R mAb is now under way.

Differential expression of gamma interferon mRNA induced by attenuated and virulent Mycobacterium tuberculosis in guinea pig cells after Mycobacterium bovis BCG vaccination.

To determine whether Mycobacterium bovis BCG vaccination would alter gamma interferon (IFN-gamma) mRNA expression in guinea pig cells exposed to Mycobacterium tuberculosis, we cloned a cDNA encoding guinea pig IFN-gamma from a spleen cell cDNA library. The cDNA is composed of 1,110 bp, with an open reading frame encoding a 166-amino-acid protein which shows 56 and 41% amino acid sequence homology to human and mouse IFN-gamma, respectively. Spleen or lymph node cells from naïve and BCG-vaccinated guinea pigs were stimulated with purified protein derivative (PPD) or M. tuberculosis H37Ra or H37Rv, and the total RNA was subjected to Northern blot analysis with a (32)P-labeled probe derived from the cDNA clone. Compared to the IFN-gamma mRNA expression in cells of naïve animals, that in spleen and lymph node cells exposed to various stimuli was enhanced after BCG vaccination. However, there was a significant reduction in IFN-gamma mRNA levels when cells were stimulated with a multiplicity of infection of greater than 1 virulent M. tuberculosis bacterium per 10 cells. The enhanced IFN-gamma mRNA response in BCG-vaccinated animals was associated with an increase in the proportions of CD4(+) T cells in the spleens, as determined by fluorescence-activated cell sorter analysis. Furthermore, the nonadherent population in the spleens enriched either by panning with anti-guinea pig immunoglobulin G-coated plates or by purification on nylon wool columns produced more IFN-gamma mRNA than whole spleen cells following stimulation with concanavalin A or PPD. This indicates that T cells are principally responsible for the upregulation of IFN-gamma mRNA expression following BCG vaccination. The mechanism by which virulent mycobacteria suppress IFN-gamma mRNA accumulation is currently under investigation.

Interleukin-10 (IL-10) in experimental visceral leishmaniasis and IL-10 receptor blockade as immunotherapy.

Interleukin-10 (IL-10) is thought to promote intracellular infection, including human visceral leishmaniasis, by disabling Th1 cell-type responses and/or deactivating parasitized tissue macrophages. To develop a rationale for IL-10 inhibition as treatment in visceral infection, Th1 cytokine-driven responses were characterized in Leishmania donovani-infected BALB/c mice in which IL-10 was absent or overexpressed or its receptor (IL-10R) was blockaded. IL-10 knockout and normal mice treated prophylactically with anti-IL-10R demonstrated accelerated granuloma assembly and rapid parasite killing without untoward tissue inflammation; IL-12 and gamma interferon mRNA expression, inducible nitric oxide synthase reactivity, and responsiveness to antimony chemotherapy were also enhanced in knockout mice. In IL-10 transgenic mice, parasite replication was unrestrained, and except for antimony responsiveness, measured Th1 cell-dependent events were all initially impaired. Despite subsequent granuloma assembly, high-level infection persisted, and antimony-treated transgenic mice also relapsed. In normal mice with established infection, anti-IL-10R treatment was remarkably active, inducing near-cure by itself and synergism with antimony. IL-10's deactivating effects regulate outcome in experimental visceral leishmaniasis, and IL-10R blockade represents a potential immuno- and/or immunochemotherapeutic approach in this infection.

Induction of the IFN-γ Gene and Protein Is Linked to the Establishment of Cell Polarity in a Porcine Epithelial Cell Line

We report here original properties of a porcine trophectoderm cell line, TBA B4-3, that developed a polarized phenotype with high transepithelial electrical resistance (TER) values and functional tight junctions (TJs) when grown on a microporous membrane. We found that treatment of polarized TBA B4-3 cells with a strong protein kinase C (PKC) agonist, phorbol 12-myristate-13-acetate (PMA), induced 3–4 days later a transient interferon-gamma (IFN-γ) mRNA expression and vectorial IFN-γ protein secretion toward the apical side of the monolayer. Exposure of TBA B4-3 cells to PMA first resulted in a rapid and profound disorganization of the monolayer structure mainly characterized by the appearance of multilayered polyp-like foci structures, a strong decrease of the TER, and a increase of permeability correlated with changes in the organization and localization of the TJ-associated proteins (ZO-1 and occludin) and filamentous actin (f-actin). After PMA removal, spontaneous return to the initial polarized monolayer state occurred, characterized by TER rising to prestimulation values, TJ protein relocalization, and multilayered cell structures fading. This return was strictly correlated with transient IFN-γ gene induction. Our report represents the first example of an inducible expression of IFN-γ by a polarized epithelial cell. After PMA treatment, the close correlation between establishment of cell polarity and IFN-γ gene expression suggests a link between these phenomena. This also suggests a novel biological mechanism by which transient and reversible disorganization of a polarized monolayer of epithelial cells could trigger regulated expression of a cytokine gene by these cells.

Interferon-gamma expression by intraepithelial lymphocytes results in a loss of epithelial barrier function in a mouse model of total parenteral nutrition.

To determine the etiology of the loss of epithelial barrier function observed with the administration of total parenteral nutrition (TPN) in a mouse model. Removal of enteral nutrition with the administration of TPN is associated with a loss of intestinal epithelial barrier function. The etiology of this barrier loss is not clear. Because intraepithelial lymphocytes (IELs) produce a number of cytokines that may alter epithelial permeability, the authors investigated IEL cytokine expression in a mouse model of TPN. Adult C57BL/6 mice received TPN or enteral diet for 7 days. IELs were subsequently harvested and the mRNA expression of cytokines was measured. Epithelial barrier function was assessed in vitro with 51Cr-EDTA in Ussing chambers and was expressed as the permeability coefficient (Papp). IEL mRNA expression of interferon-gamma (IFN-gamma) rose from 0.14 +/- 0.07 in the control (enterally fed) group to 0.44 +/- 0.11 attomoles/microL in the TPN group (P <.05). Transforming growth factor-beta1 declined slightly but not significantly, from 0.75 +/- 0.35 to 0.55 +/- 0.18 attomoles/microL in the control and TPN groups, respectively. Epithelial barrier function declined significantly with TPN compared to controls. To assess the relevance of IFN-gamma changes, permeability in IFN-gamma knockout mice was studied. Barrier function was significantly higher in IFN-gamma knockout mice on TPN compared to C57BL/6 mice that received TPN. IEL cytokine expression changes significantly with TPN administration. The partial correction with IFN-gamma knockout mice suggests that an upregulation of IFN-gamma expression is one mechanism responsible for the loss of the epithelial barrier associated with TPN.

Dynamics of mycobacterial HSP65-induced T-cell cytokine expression during oral tolerance induction in adjuvant arthritis.

To investigate whether oral administration of mycobacterial heat-shock protein 65 (HSP65) during adjuvant arthritis (AA) induces regulatory cells and cytokines. AA was induced in Lewis rats and from the time of disease onset HSP65 in the presence of soya bean trypsin inhibitor (STI) was administered orally every other day. The number of splenic CD4+CD25+ T cells and antigen-induced cytokine mRNA expression were determined. Oral treatment with HSP65/STI reduced AA symptoms. After one feeding of HSP65/STI, the number of CD4+CD25+ splenic T cells increased and HSP65-specific T cells expressed increased levels of interferon gamma and interleukin 10. After two feedings, the expression of interleukin-10 mRNA remained increased, whereas there was low expression of interferon gamma mRNA. The number of CD4+CD25+ splenic T cells remained increased. Oral treatment with HSP65/STI after AA onset reduces disease symptoms via dynamic changes in the number of CD4+CD25+ splenocytes and in antigen-induced cytokine production.