IL-12 and IFN-gamma production, and NK cell activity, in acute and chronic experimental Trypanosoma cruzi infections

Resistance to acute Trypanosoma cruzi infection is mainly associated with a Th1 immune response, characterized by gamma-interferon (IFN-gamma) production and activation of macrophages. The outcome of the Th1 response in the spleen and serum of BALB/c and C3H mice infected with T. cruzi, Tulahuén strain was studied. The levels of interleukin-12 p40 (IL-12 p40) and IFN-gamma, as well as natural killer (NK) cell cytotoxicity were determined at different time-points during the acute phase, and the production of cytokines was also studied in the chronic infection. At 2 days post-infection (pi), spleen cells from C3H mice increased their NK cell activity and the ex vivo spontaneous release of both IL-12 p40 and IFN-gamma. On the other hand, BALB/c mice reached low levels of NK cell cytotoxicity and no IFN-gamma production was detected at this time pi, but the cytokine was released at high amounts in the second week of the infection. Seric IL-12 p40 concentrations showed a 3-fold increase in both mouse strains on the second day pi and remained high throughout the acute phase. However, seric IFN-gamma levels increased during the late acute infection and were higher in BALB/c than in C3H mice. In chronically infected mice IL-12 p40 was as high as in the acute phase in the serum of both strains, but only BALB/c mice still produced IFN-gamma. To the authors' knowledge this is the first report showing the protein levels of IL-12 p40 determined in vivo in acute and chronic T. cruzi infections. The results reveal differences between both mouse strains in the mechanisms controlling the onset and fate of the Th1 response triggered by the parasite and a long lasting pro-inflammatory stimuli.     

Antigen-specific production of interleukin (IL)-13 and IL-5 cooperate to mediate IL-4Ralpha-independent airway hyperreactivity

The pathogenesis of human asthma and the development of key features of pulmonary allergy in mouse models has been critically linked to IL-13. Analyses of the receptor components employed by IL-13 have shown that delivery of this cytokine to the airways of naive IL-4Ralpha gene targeted (IL-4Ralpha(-/-)) mice fails to induce disease, suggesting that this membrane protein is critical for transducing IL-13-mediated responses. The current study demonstrates that, in contrast to naive mice, T helper 2 bias, airways hyperreactivity (AHR) and tissue eosinophilia develop in Ovalbumin-sensitized IL-4Ralpha(-/-) mice and that these responses can be inhibited by the IL-13 antagonist sIL-13Ralpha2Fc. Therefore, antigen stimulation induces an IL-13-regulated response that is independent of IL-4Ralpha. To determine the role of IL-5 and eosinophils in the development of disease in antigen-exposed IL-4Ralpha(-/-) mice, pulmonary allergy was examined in mice deficient in both factors. IL-4Ralpha/IL-5(-/-) mice were significantly defective in their ability to produce IL-13 and failed to develop AHR, suggesting that IL-5 indirectly regulates AHR in allergic IL-4Ralpha(-/-) mice by an IL-13-dependent mechanism. Collectively, these results demonstrate that IL-13-dependent processes regulating the development of AHR and T helper bias persist in the in the lungs of allergic IL-4Ralpha(-/-) mice.     

Role of interleukin (IL)-18 in experimental paracoccidioidomycosis.

Interleukin (IL)-18 has been regarded as a Th1 type cytokine involved in many fungal and parasitic infections. Since there have been no studies, as of yet, evaluating the role of this cytokine in paracoccidioidomycosis (PCM), we assessed the function of IL-18 by using an experimental PCM model. Our results showed that IL-18 knockout (IL-18 -/-) BALB/c were more resistant to Paracoccidioides brasiliensis than their littermate controls (WT). In fact, mortality rate was higher in WT mice and in the first month of infection, the number of colony forming units of the etiologic agent recovered from the lungs was greater in WT mice. In histopathological analyses, well-formed granulomas were seen in both WT and IL-18(-/-) mice. However, substantial differences were observed at the second month of infection when epithelioid cells predominated in the lesions of IL-18(-/-) mice, which could infer that IL-18 postpones pulmonary healing. The levels of IL-10 were significantly higher in IL-18 sufficient mice at early stages of infection and therefore account for the delayed fungal clearance observed in WT mice. TNF-alpha augmented later in the infection of WT mice, seemingly to compensate high levels of IL-10. Our results demonstrated that IL-18 has a critical role in protecting BALB/c mice against disseminated PCM.     

Histamine inhibits lipopolysaccharide-induced interleukin (IL)-18 production in human monocytes

Lipopolysaccharide (LPS) is an inducer of interleukin (IL)-18, which in turn plays important roles in immune responses. Previously, we reported that tumor necrosis factor (TNF)-alpha production could be detected in human peripheral blood mononuclear cells (PBMCs) treated with relatively low concentration of LPS (1 ng/ml), but that same concentration of LPS could not induce IL-18 production. In the present study, we found that LPS at relatively high concentrations (10-1000 ng/ml) induced IL-18 production in a concentration-dependent manner both in monocytes isolated from PBMC, and that histamine (10(-7) to 10(-4) M) inhibited IL-18 production induced by LPS. The studies using receptor subtype-selective agonists and antagonists suggested that the effect of histamine was mediated by H2 receptor but not by H1, H3 and H4 receptors. Therefore, the stimulation of H2 receptor might be beneficial in the treatment of sepsis through inhibiting LPS-elicited IL-18.     

The contribution of interleukin (IL)-4 and IL-13 to the epithelial-mesenchymal trophic unit in asthma

Interleukin (IL)-4 and IL-13 are key proinflammatory cytokines in asthma. Studies in transgenic mice show that both cytokines cause inflammation, but only IL-13 causes subepithelial fibrosis, a characteristic feature of asthma. We compared the in vitro profibrogenic effects of IL-4 and IL-13 using bronchial fibroblasts from asthmatic subjects. In the presence of transforming growth factor (TGF)-beta the cells transformed into contractile myofibroblasts and expressed alpha-smooth muscle actin and procollagen I. IL-4 and IL-13 also stimulated proliferation, but were relatively ineffective in promoting myofibroblast transformation. TGF-beta was more potent than the cytokines in stimulating release of endothelin-1 and vascular endothelial growth factor, whereas IL-4 and IL-13 were more potent stimuli for eotaxin release. Although neither IL-4 nor IL-13 induced profibrotic responses, both cytokines caused a corticosteroid-insensitive stimulation of TGF-beta2 release from primary bronchial epithelial cells. These data indicate that epithelial activation by IL-13 or IL-4 plays a critical role in initiating remodeling through release of TGF-beta2. TGF-beta2 then activates the underlying myofibroblasts to secrete matrix proteins and smooth muscle and vascular mitogens to propagate remodeling changes into the submucosa. In contrast, direct activation of submucosal fibroblasts by IL-4 and IL-13 has a proinflammatory effect via eotaxin release and recruitment of eosinophils into the airways.     

Alveolar macrophage interleukin (IL)-10 and IL-12 production in atopic asthma

Inflammation in asthma is characterized by a Th2 response. In many experimental systems, this response can be regulated by interleukin (IL)-IO and IL-12. IL-10 deactivates T cells, and IL-12 reorients the response toward a Till pattern. Alveolar macrophages (AM) can secrete both of these cytokines, and thus regulate T-cell behavior in asthma. They can enhance the Tli2 response by turning off their secretion of IL-10 and IL-12. or tend to downregulate it by producing these cytokines. To elucidate that point, we assayed the AM IL-10 and IL-12 from 11 asthmatic patients and four controls. Six asthmatics were treated by inhaled corticosteroids. AM were recovered by bronchoalveolar lavage (BAL). They were isolated and cultured for 24 h without stimulation or in the presence of lipopolysaccharide (LPS), IL-10 and the p40 subunit of IL-12 were assayed in the BAL fluid and i n AM culture supernatants by ELISA. Spontaneous AM IL-10 production was higher in asthmatics, particularly in the treated group. The AM IL-10 production after stimulation by LPS was also elevated in asthmatics, but was mainly so in untreated patients. IL-12 levels were higher in BAL fluids from untreated patients than from controls. The IL-12 production of LPS-stitnulated-AM from these patients was increased. These results show that AM are at least primed for the production of IL-10 and IL-12 in asthma, and suggest that these cells could be involved in the resolution of the asthmatic inflammation.     

Interleukin (IL)-4, IL-10, IL-18 and IFN-gamma cytokines pattern in patients with combined hepatitis C virus and Schistosoma mansoni infections

Schistosoma mansoni infection is characterized by a strong T-helper type 2 (Th2) cell-associated immune response, but in the case of viral infection, it is associated with interferon-gamma (IFN-gamma) increase and induction of Th1 immune response. Few data are available about the immune response of cases infected with combined hepatitis C virus (HCV) and schistosomiasis. Thus, the investigation of the cytokine pattern in patients coinfected with both HCV and Schistosoma mansoni was our rationale. This study included four patient groups: Group 1 included 20 patients infected with chronic HCV, Group 2 included 15 patients infected with schistosomiasis alone, Group 3 included 20 patients with chronic HCV and schistosomiasis and Group 4 included 15 healthy control individuals with matched age and sex. Serum levels of IFN-gamma, interleukin (IL)-4, IL-10 and IL-18 were measured in all groups by enzyme-linked immunosorbent assay. The results showed that the patients infected with HCV had significantly higher serum levels of IFN-gamma and IL-18 compared with the controls and with the patients with schistosomiasis and coinfection (P < 0.001). On the other hand, serum levels of IL-4 and IL-10 were significantly higher in patients with schistosomiasis and coinfection compared with the control group (P < 0.001 and 0.0001, respectively) and with the HCV patients (P < 0.05 and P < 0.001, respectively). A significant increase in serum levels of IL-4 and IL-10 was also found in HCV patients compared with the control (P < 0.05). Schistosomiasis appears to induce a Th2 cytokine profile, with increase in serum levels of IL-4 and IL-10, even in the presence of HCV coinfection. In conclusion, schistosomiasis may downregulate the stimulatory effect of HCV on Th1 cytokines and this may lead to the chronicity of HCV infection in coinfected patients.     

Involvement of interleukin (IL)-13, but not IL-4, in spontaneous IgE and IgG4 production in nephrotic syndrome

Nephrotic syndrome (NS) is a renal disease characterized by proteinuria and hypoalbuminemia. In NS patients without any allergic disease, serum IgE and IgG4 levels were selectively increased, and peripheral blood mononuclear cells (MNC) spontaneously produced IgE and IgG4. T cells produced interleukin (IL)-13 spontaneously, and B cells constitutively expressed IL-13 receptors (IL-13R). In addition, T cells stimulated surface IgE-negative (sIgE^?) and sIgG4^? B cells to produce IgE and IgG4, respectively, and IgE and IgG4 production was specifically blocked by anti-IL-13 antibody (Ab). MNC from atopic dermatitis (AD) patients also produced IgE and IgG4 spontaneously. However, in AD patients, T cells spontaneously produced IL-4, but not IL-13, and B cells constitutively expressed IL-4R, but not IL-13R. T cells stimulated sIgE^? and sIgG4^? B cells to produce IgE and IgG4, respectively, and the production was specifically blocked by anti-IL-4 Ab. On the other hand, sIgE⁺ and sIgG4⁺ B cells from both NS and AD patients spontaneously produced IgE and IgG4, respectively, and this production was not affected by T cells, anti-IL-4 Ab, or anti-IL-13 Ab. These results indicate that IL-13 is involved in the enhanced production of IgE and IgG4 in NS, while IL-4 is involved in these responses in AD.     

The combined effect of interleukin (IL)-10 and IL-12 polymorphisms on induced cytokine production

Interleukin (IL)-12 and IL-10 are immunoregulatory cytokines with an antagonistic effect of the T-helper (Th)1/Th2 cytokine balance and provide a functional link between innate and adaptive immune responses. The aim of the study was to investigate the combined effect of -1082A*G in IL10 and +16974A*C in IL12B single nucleotide polymorphisms (SNPs) on induced cytokine production by stimulated peripheral blood mononuclear cells (PBMCs) isolated from healthy donors. The presence of the high-producer IL-12p40 genotype led to diminished production of IL-10 as determined by the -1082*G allele of SNP in IL10. Significantly decreased IL-10 production was detected in AA+AG/GG in comparison with the low-producer IL-12p40 (AC/CC+AG/GG) genotype combination after stimulation with C3bgp (2 +/- 4 vs. 29 +/- 14.2 pg/ml; p = 0.0003) and LPS (33.4 +/- 13.5 vs. 93.3 +/- 59.6 pg/ml; p = 0.019). IL-12p40 production was independent of IL10 genotype. The present results demonstrated that the production of IL-10 from PBMC depended on both -1082A*G in IL10 and +16974A*C in IL12B polymorphisms.     

Fine structure of interleukin 18 (IL-18) receptor-immunoreactive neurons in the retrosplenial cortex and its changes in IL18 knockout mice

Interleukin 18 (IL-18) participates in the inflammatory immune response of lymphocytes. Delay in learning or memory are common in the IL-18 knockout mouse. Many IL-18-immunoreactive neurons are found in the retrosplenial cortex (RSC) and the subiculum. These neurons also contain the IL-18 receptor. We determined the location and the ultrastructure of the IL-18 receptor-immunoreactive neurons in the RSC and observed changes in the IL-18 receptor-immunoreactive neurons of the IL-18 knockout mouse. The IL-18 receptor-immunoreactive neurons were found specifically in layer V of the granular RSC. They were medium-sized neurons with a light oval nucleus and had little cytoplasm with many free ribosomes, rough endoplasmic reticulum and many mitochondria, but no Nissl bodies. The number of axosomatic terminals was about six per section. The IL-18 receptor-immunoreactive neurons were not found in the RSC in the IL-18 knockout mouse at 5 or 9 weeks of age. However, many small electron-dense neurons were found in layer V. Both the nucleus and cytoplasm were electron-dense, but not necrotic. The mitochondria and rough endoplasmic reticulum were swollen. The IL-18 receptor-immunoreactive neurons were presumed to be degenerating. The degeneration of the IL18-receptor-immunoreactive neurons in the RSC may cause the abnormal behaviors of the IL-18 knockout mice.     

The effect of additional brain injury on systemic interleukin (IL)-10 and IL-13 levels in trauma patients

OBJECTIVE: Besides interleukin (IL)-10, accumulating evidence from in vitro studies has indicated a strong antiinflammatory capacity for IL-13. A prospective clinical study was undertaken to assess the influence of additional brain injury on systemic IL-10 and IL-13 levels as markers for the antiinflammatory state in trauma patients. MATERIAL AND METHODS: The course of IL-10 and IL-13 plasma levels from 32 patients with an isolated severe head trauma (SHT), 50 patients with multiple injuries and additional SHT and 39 patients with multiple injuries without SHT was detected using ELISA-technique. Blood samples from 37 healthy blood donors were analysed for control. RESULTS: IL-10 levels were significantly elevated in all 3 injury groups within 3 h after trauma. The lowest initial release was detected in patients with an isolated SHT (Injury severity score; ISS: 18.1 +/- 5.6). No difference could be demonstrated for the IL-10 levels from multiple injured patients with (ISS: 35.3 +/- 9.6) or without additional SHT (ISS: 25.5 +/- 11.7), though there were relevant differences in the ISS. In contrast, the IL-13 plasma levels were not elevated systemically after trauma. CONCLUSIONS: IL-10 but not IL-13 is a detectable antiinflammatory marker in trauma patients with or without brain injury and to a minor degree in patients with an isolated SHT.     

Coculture of Th cells with interleukin (IL)-7 in the absence of antigenic stimuli induced T-cell anergy reversed by IL-15

Interleukin-7 (IL-7) is an important survival factor for T cells. We report here for the first time that it has another important role, facilitating T-cell clonal unresponsiveness, or anergy. The anergy was induced by a 20-day coculture of activated-human CD4(+) T-cell clones with IL-7 and irradiated peripheral blood mononuclear cells without antigenic stimuli. T-cell survival, but not T-cell anergy induction, was dependent on direct cell contacts between T cells and irradiated peripheral blood mononuclear cells. The anergic T cells exhibited no or very low expression of IL-7 receptor alpha chain (IL-7Ralpha), IL-2 receptor alpha chain (IL-2Ralpha), and common gamma chain (gammac), and did not express cytotoxic T-lymphocyte-associated protein 4, but expressed IL-15Ralpha. Coculture for 3 to 9 days of anergic T cells with a T-cell-activating cytokine IL-15, but not IL-2, restored the responsiveness of IL-7-induced anergic T cells together with reexpressions of IL-7Ralpha, IL-2Ralpha, and gammac. The anergy induction by IL-7 and restoration of responsiveness by IL-15 suggest novel mechanisms for regulation of helper T-cell responses, induction of peripheral tolerance, and breakdown of T-cell self-tolerance.     

Relationship of seminal plasma interleukin (IL) -8 and IL-6 with semen quality

The concentration of interleukin (IL) -8 and IL-6 was determined in seminal plasma (SP) samples from 137 randomly chosen subfertile males to evaluate the relationship with other potential parameters of subclinical infection/inflammation such as seminal leukocytes, and with semen quality in a prospective study. All patients were asymptomatic for genital tract infection. A comprehensive semen evaluation included sperm analysis, sperm migration testing, antisperm antibody screening, immunocytochemical round cell differentiation to determine seminal leukocytes counts and the leukocyte ratio, complement fraction C(3) (C(3c)) determination, and semen cultures, in aliquots of the same ejaculates. The SP concentration of IL-8 was inversely related to semen quality, e.g. to the total number of motile spermatozoa or to the outcome of the sperm migration test (motile sperm harvested after a swim-up procedure). IL-8 concentrations were significantly correlated with leukocyte counts per ml (P < 0.0001) and per ejaculate (P < 0.0001), and with the leukocyte ratio (P < 0.001). All leukocytospermic samples had high IL-8 concentrations (< or =2 ng/ml). The SP concentration of IL-6 was much lower, but was significantly correlated with IL-8 (P < 0.0001). Both IL-8 and IL-6 were significantly related with the C(3c). No association of interleukin concentrations with the bacterial colonization of semen samples was found. The results indicate a marked relationship of some pro-inflammatory cytokines with semen quality. The significant association with seminal leukocytes and other potential inflammation markers suggests that IL-8 might be used as sensitive marker for silent male genital tract infection.     

Concanavalin A-induced hepatitis in mice is prevented by interleukin (IL)-10 and exacerbated by endogenous IL-10 deficiency

One single intra-venous (i.v.) injection of Concanavalin A (Con A) into mice provokes a cell-mediated immunoinflammatory hepatitis. We have presently evaluated the immunopharmacological effects of exogenous interleukin (IL)-10 and the role of endogenous IL-10 in this model by using exogenous IL-10, anti-IL-10 monoclonal antibody (mAb) and mice with disrupted IL-10 gene (IL-10 KO mice). Whilst exogenous IL-10 administered in a prophylactic (1 h prior to Con A) and even "early" therapeutic fashion (30 min after Con A) reduced the elevation of transaminase activities in plasma in a dose-dependent manner, observed in control mice, these biochemical markers of liver injury were significantly increased both in IL-10 KO mice as well as in those receiving anti-IL-10 mAb. Interestingly, doses of Con A lower than 20 mg/kg that were only capable of inducing slight serological signs of hepatitis in mice, exerted marked hepatitic effects when administered to either anti-IL-10 mAb-treated mice or to IL-10 KO mice. The disease modulating effects of exogenous IL-10 and either genetical or pharmacologically-induced IL-10 deficiency were associated with profound and opposite modifications of the Con A-induced increase in the circulating levels of IFN-gamma and TNF-alpha. Relative to control animals, the blood levels of these cytokines were diminished in IL-10-treated mice and augmented in both IL-10 KO mice and anti-IL-10 mAb-treated mice. These results prove the physiological antiinflammatory role of endogenous IL-10 in Con A induced hepatitis and the beneficial effects of IL-10 treatment to prevent this condition.     

Interrelationships between interleukin (IL)-1, IL-6 and IL-8 in synovial fluid of various arthropathies

High levels of many cytokines, including interleukin (IL)-1, IL-6 and IL-8, were found in various arthropathies suggesting that they play a role in the pathogenesis of disease, although their relationship with the type and activity of disease is still not clear. The synovial fluid (SF) of 24 patients with rheumatoid arthritis (RA), 19 with psoriatic arthritis (PA) and 33 with osteoarthritis (OA) was analyzed for IL-1, IL-6 and IL-8. The highest concentration of the three cytokines was found in the SF of RA. IL- detectable levels (>-20 pg/ml) were observed in 8/24 (33.3%) patients with RA, in one patient with PA but in no patient with OA.IL-6 (mean±SD) (1610.37±1781.65 pg/ml) was higher in RA than in PA (672.47±867.40 pg/ml,p=0.043) and OA (89.45±120.52 pg/ml,p=0.0001). IL-8 (1042.72±698.64 pg/ml) was higher in RA than in PA (660.36±625.11 pg/ml,p=0.03) and OA (89.9±45.88 pg/ml,p=0.0001). A correlation between IL-1, IL-6 and IL-8 was found in RA. In all patients a correlation between IL-6 and IL-8 levels was found; moreover, these two cytokines were associated with SF indices of inflammation, such as white blood cells (WBC) count and total protein (TP) concentration.Out findings suggest that these interrelationships play a role in the evolution of more severe erosive arthropathy such as RA.     

Selective and differential binding of interleukin (IL)-1 alpha, IL-1 beta, IL-2 and IL-6 to glycosaminoglycans.

The binding of interleukin (IL)-1 alpha, IL-1 beta, IL-2 and IL-6 to acidic polysaccharides was investigated by affinity chromatography of the recombinant, radioiodinated interleukins on columns of immobilized polysaccharide. Each interleukin showed selective binding retention. Overall heparin bound all four interleukins significantly, whereas chondroitin sulfate provided little retention. IL-1 alpha and IL-1 beta showed differential binding, with only the latter binding to hyaluronic acid. IL-2 was virtually completely retained on fucoidan. Noniodinated recombinant IL-2 bound similarly to fucoidan, and fucoidan was found to sequester IL-2 activity in a bioassay employing IL-2-dependent CTLL cells. In all other cases tested, interleukin retention was partial, implying that interleukin binding sites are sparsely distributed along the polysaccharide chains. These findings suggest that during the immune response, interleukins will tend to be retained at sites of secretion by interaction with glycosaminoglycans in the extracellular matrix and on cell surfaces.