Concentrations of cytokines,soluble interleukin-2 receptor,and soluble CD30 in sera of patients with hepatitis B virus infection during acute and convalescent phases

The immunoregulatory roles of interleukin-2 (IL-2), IL-4, IL-10, gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), the soluble form of the IL-2 receptor (sIL-2R), and the soluble form of CD30 (sCD30) were evaluated in patients with hepatitis B virus (HBV) infection. Two groups of subjects were studied: 15 healthy individuals without hepatitis antecedents and 15 patients with HBV infection. Blood samples were taken during the acute and convalescent phases. The analysis of the samples was done by the enzyme-linked immunosorbent assay technique. IFN-gamma and TNF-alpha levels decreased in the convalescent phase. IL-10, IL-2, and sIL-2R levels increased in the acute and convalescent phases, while sCD30 levels increased during the acute phase. The IL-4 concentrations decreased in both phases. During the acute phase, IFN-gamma and TNF-alpha induced increases in IL-2, sIL-2R, IL-10, and sCD30 levels in serum, which allowed the development of immunity characterized by the nonreactivity of the HBV surface antigen, the onset of antibodies to the HBV surface antigen (anti-HBs), and normal alanine aminotransferase levels during the convalescent phase. Increased IL-2 levels during the acute phase would stimulate the activities of NK cells and CD8(+) lymphocytes, which are responsible for viral clearing. The raised sIL-2R levels reveal activation of T lymphocytes and control of the IL-2-dependent immune response. The sCD30 increment during the acute phase reflects the greater activation of the Th2 cellular phenotype. Its decrease in the convalescent phase points out the decrease in the level of HBV replication. The increase in IL-10 levels could result in a decrease in IL-4 levels and modulate IFN-gamma and TNF-alpha levels during both phases of disease, allowing the maintenance of anti-HBs concentrations.     

Age-Dependent Levels of Select Immunological Mediators in Sera of Healthy Children

Serum cytokine levels were measured in 275 healthy children of different ages (3 to 17 years). Interleukin-1 receptor antagonist (IL-1RA), soluble IL-2R (sIL-2R) (sCD25), IL-6, IL-8, tumor necrosis factor alpha (TNF-α), soluble TNF receptor type II (sTNF-RII) (sCD120b), gamma interferon (IFN-γ), soluble intercellular adhesion molecule 1 (sICAM-1) (sCD54), soluble E selectin (sE-selectin) (ELAM-1; sCD62E), sCD14, and neopterin were measured with commercial test kits. The mean levels of IL-1RA, sIL-2R, TNF-α, sICAM-1, sE-selectin, and sCD14 were higher than in healthy adults. In contrast, IFN-γ and IL-8 were hardly detectable in children and thereby significantly lower than in adults. In the case of TNF-α, sICAM-1, sE selectin, and sCD14, there was a high interindividual variability, apparently unrelated to disease. The profiles of some cytokines, i.e., IL-1RA, IL-6, and TNF-α, showed age-related increases that overlapped with known patterns of physical growth. Of note, sIL-2R and sE-selectin instead declined with time. Because of the remarkable age-dependent variability in healthy pediatric subjects, disease-related changes, as well as therapy-dependent alterations, should be considered with caution.     

Patterns of Cytokines and Soluble Cellular Receptors in the Sera of Children with Acute Chagas' Disease

Cytokines and soluble cellular receptors are involved in inflammatory processes and probably in the pathogenesis of parasite and bacterial diseases. In a previous study, we reported increased levels of soluble receptors of interleukin-2 (sIL2-R) in children with acute Chagas' disease, one of the main parasitic infections that is endemic in Latin America. We sought to analyze the pattern of different cytokines and soluble receptors in the sera of children with chagasic infection. Children with acute and indeterminate stages of Chagas' disease, as well as nonchagasic children, were studied. Sera were assayed by enzyme-linked immunosorbent assay to measure the levels of tumor necrosis factor alpha (TNF-α), IL-6, IL-2, IL-8, IL-12, sIL-2R, and the soluble receptors of CD8 and CD4 (sCD8 and sCD4). sIL-2R and sCD8 showed the highest levels in serum in acutely infected children, decreasing after specific antiparasite therapy. Chronic children showed a pattern similar to the one of nonchagasic children. Although they were not statistically significant, TNF-α, IL-6, and sCD4 showed a tendency to reach high levels in the acutely infected group, whereas IL-2, IL-8, and IL-12 did not reveal changes with respect to the noninfected children. In summary, we report here the patterns of cytokines and soluble receptors in in the sera of children infected with Trypanosoma cruzi; we found significantly increased levels of sIL-2R and sCD8 in acute infection that decreased after therapy, and high levels of TNF-α, IL-6, and sCD4 in some of the acute patients. The measurement of sIL-2R and sCD8 may provide a useful tool in the follow-up of children with Chagas' disease.     

Significantly Higher Cytokine and Chemokine Levels in Patients with Japanese Spotted Fever than in Those with Tsutsugamushi Disease

Tetracyclines are administered to cure Japanese spotted fever (JSF) and tsutsugamushi disease (TD). It is generally said that the clinical course of JSF is worse than that of TD despite antibiotic treatment. The precise mechanism underlying the more severe clinical course of JSF is not fully understood. We therefore examined whether the differential cytokine profile between these two infectious diseases contributes to the difference in clinical severity. The serum concentrations of various cytokines (tumor necrosis factor alpha [TNF-α], interleukin-6 [IL-6], and gamma interferon [IFN-γ]) and chemokines (IL-8, interferon-inducible protein 10 [IP-10], monocyte chemoattractant protein 1 [MCP-1], macrophage inflammatory protein 1α [MIP-1α], MIP-1β, and eotaxin) were measured in 32 TD and 21 JSF patients. The results showed that serum levels of TNF-α in the acute phases of TD and JSF were significantly increased, with a higher concentration of TNF-α in patients with JSF (mean, 39.9 pg/ml) than in those with TD (mean, 13.8 pg/ml). Comparatively higher levels of other cytokines and chemokines (IL-6, IFN-γ, IL-8, IP-10, MCP-1, MIP-1α, and MIP-1β) were also observed in the acute phase of JSF. The clinical severity score (3.67 ± 1.71) of JSF patients was higher than that of TD patients (1.47 ± 0.77). Our findings revealed that the cytokine and chemokine levels in the acute phase of JSF were significantly higher than those in the acute phase of TD. The differential cytokine levels may be related to the difference in clinical severity between JSF and TD.     

An assessment of peripheral immunity in patients with sarcoidosis using measurements of serum vitamin D3, cytokines and soluble CD23

The aetiology of the peripheral anergy in sarcoidosis is unclear. To investigate this further we measured the serum levels of several factors important in different aspects of immune regulation to obtain a profile of those factors which promote and inhibit immune activation in sarcoidosis. Thirty-seven patients with sarcoidosis and 20 healthy controls of similar sex and age comprised the study group. Serum IL-10, interferon-gamma (IFN-γ), soluble CD23 (sCD23), IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1β and tumour necrosis factor-alpha (TNF-α) were measured using in-house ELISAs. Vitamin D3 was measured using a radioreceptor assay. Serum levels of sCD23 and IL-10 were significantly elevated in patients with sarcoidosis relative to controls (median 13.9 versus 9.5 arbitrary units/ml, P < 0.01 for sCD23, and 9.6 versus 5.0 pg/ml, P < 0.04 for IL-10). Regardless of steroid therapy or disease activity, serum levels of IFN-γ, TNF-α, IL-1β, GM-CSF and IL-8 were no different in patients with sarcoidosis and controls. Vitamin D3 levels were significantly higher in patients with sarcoidosis versus normal controls (medians 78.0 versus 56.0, P < 0.001), active sarcoidosis (n = 20) versus inactive disease (n = 17) (medians 81.5 versus 66.0, P < 0.03) and active sarcoidosis versus controls (medians 81.5 versus 56.0, P < 0.0002). The levels were no different between patients with inactive sarcoidosis and controls. We suggest that IL-10 and vitamin D3 may contribute to the peripheral anergy in sarcoidosis. The elevated serum sCD23 suggests an increase in peripheral humoral immunity. Consistent with a quiescent peripheral immune system, factors capable of monocyte/macrophage activation (TNF-α, IFN-γ, GM-CSF and IL-8) were not elevated in the peripheral circulation.     

Haemophilus influenzae and Streptococcus pneumoniae induce different intracerebral mRNA cytokine patterns during the course of experimental bacterial meningitis

Using in situ hybridization with radiolabelled oligonucleotide probes, we studied the mRNA expression of IL-1β, IL-4, IL-6, IL-10, IL-12, tumour necrosis factor-alpha (TNF-α), TNF-β, interferon-gamma (IFN-γ), and transforming growth factor-beta (TGF-β) in the brain during the lethal course of experimental meningitis in a rat model inoculated intracisternally with Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae and in uninfected control rats inoculated with the same volume of PBS. The production of IL-1β, IL-4, IL-6 and IFN-γ was also evaluated by immunohistochemistry. In the brain of Hib-inoculated rats, there was marked mRNA expression of IL-1β, IL-6, TNF-α, IL-12 and IFN-γ. IL-1β, IL-6 and TNF-α were up-regulated throughout the observation period at 2, 8 and 18 h post-inoculation (p.i.), with similar patterns of induction. The Th1 cytokines IFN-γ and TNF-β were up-regulated within 8 h p.i. IL-10 and TGF-β were down-regulated at 18 h p.i., while IL-4 was not detected. In contrast, the brain of S. pneumoniae-inoculated rats showed lower levels of IL-1β, IL-6 and TNF-α, but higher levels of TNF-β and detectable mRNA expression of IL-4 when compared with Hib-inoculated rats. IL-12, IFN-γ, IL-10 and TGF-β exhibited similar patterns of induction in the brains of Hib- and S. pneumoniae-inoculated rats. At 18 h p.i., immunohistochemistry showed similar patterns of IL-1β, IL-4, IL-6 and IFN-γ as mRNA expression in the brains of Hib- and S. pneumoniae-inoculated rats. The differences of cytokine profiles induced by the two bacterial strains may imply that different immunomodulating approaches should be considered, depending on etiology.     

Serum Cytokines in Patients with Legionella Pneumonia: Relative Predominance of Th1-Type Cytokines

Serum samples from 14 patients with Legionella pneumonia were examined for the presence of cytokines. In spite of high levels of serum C-reactive protein in all patients during the acute phase in only four cases (one involving interleukin-1β [IL-1β], three involving IL-6, and none involving tumor necrosis factor alpha) was the concentration of cytokines more than 100 pg/ml. Th2 cytokines IL-4 and IL-10 were detected in only one patient each. In contrast, significant increases of serum gamma interferon (IFN-γ) and IL-12 levels were observed during the acute phase in 6 and 11 cases, respectively. Interestingly, although serum IFN-γ levels diminished thereafter, in seven cases IL-12 levels remained high or increased further during the convalescent phase. In an additional 22 cases clinically suspected to be but not diagnosed as Legionella pneumonia, increases of serum IL-12 levels were observed in 16 cases, whereas the remaining 6 cases showed no detectable IL-12. Our results demonstrate the relative predominance of Th1 cytokine production in Legionella pneumonia. Although the role and significance of prolonged increases in IL-12 levels in Legionella disease are unknown, our results should prompt further investigation of the host immune response in terms of Th1 and Th2 balance in legionellosis.     

Cytokine production in synovial tissue of mice with collagen-induced arthritis (CIA)

The kinetics of cytokine production in arthritic limbs of mice with CIA was determined by using modified immunohistochemical techniques. Tissue cryostat sections of undecalcified whole paws were analysed for the presence of tumour necrosis factor-alpha (TNF-α), IL-6, IL-2, IL-4, IL-5 interferon-gamma (IFN-γ), transforming growth factor-beta 2 (TGF-β2) and TGF-β3. Locally produced TNF-α, IL-6 and TGF-β2 were observed within the lining layer, sublining and pannus at all stages of disease. The staining of TNF-α was particularly intense at the cartilage–pannus junction. In contrast to the monokines, IFN-γ and TGF-β3 were only expressed in scattered cells within the deeper layers of the synovia. Interestingly, IFN-γ was not present in the late phase of CIA, despite the continued presence of TNF-α and IL-6 in the pannus. Production of IL-2, IL-4 or IL-5 was not detected in any joint. The observed pattern of a relative paucity of T cell-derived cytokines and an abundance of monokines during the late phase of T cell-dependent CIA indicates that the synovial cytokine pattern previously described in rheumatoid arthritis (RA) is fully compatible with a pathogenic role of T cells. The temporal as well as spatial dissociation between expression of T cell-derived cytokines and monokines indicates that T cell-independent mechanisms may also be of importance in the triggering of monokine production during arthritis.     

A distinct pattern of cytokine production from blood mononuclear cells in multitransfused patients with β-thalassaemia

The unstimulated and induced production of granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), IL-3, IL-6, stem cell factor (SCF), IL-1β, tumour necrosis factor-alpha (TNF-α), TNF-β, interferon-gamma (IFN-γ) and transforming growth factor-beta (TGF-β) was determined after culture of blood mononuclear cells from 22 patients with severe β-thalassaemia in a regular transfusion programme, five non-regularly transfused patients with β-thalassaemia intermedia and nine normal persons. A distinct pattern of cytokine production in thalassaemic patients was detected, namely a low unstimulated production of all cytokines and a significant increase in the stimulated production of IFN-γ, TNF-α and IL-1β; these abnormalities were more pronounced in the more heavily transfused older patients. The increased production of the above cytokines, which usually characterize the acute response to infectious agents and have a negative effect on erythropoiesis, may explain the deterioration of anaemia found in thalassaemic patients during acute infections.     

The IL-1 system in HIV infection: peripheral concentrations of IL-1β, IL-1 receptor antagonist and soluble IL-1 receptor type II

The proinflammatory cytokine IL-1β is thought to be involved in ongoing HIV disease. Furthermore, its naturally occurring inhibitors soluble IL-1 receptor type II (sIL-1RII) and IL-1 receptor antagonist (IL-1Ra) may play a pivotal role in regulating its biological action. To investigate the involvement of the IL-1 system we determined serum levels of IL-1β, IL-1Ra and sIL-1RII in 90 HIV⁺ patients. The obtained values were compared with markers of disease progression such as CD⁺ count, 5′-neopterin, β₂-microglobulin and soluble tumour necrosis factor receptors (sTNF-R) p55 and p75 and then compared with C-reactive protein (CRP), granulocyte count, lL-6 and TNF-α. While IL-1Ra concentrations increased significantly with progressive CDC disease stages, sIL-1RII and IL-1β were not altered in our cohort. IL-1Ra showed statistical relation to decreasing CD4⁺ lymphocytes and increasing 5′-neopterin, β₂-microglobulin, sTNF-R p55, sTNF-R p75. Furthermore, IL-1Ra correlated positively with serum IL-6, TNF-α, CRP and granulocytes. In contrast, sIL-1RII and IL-1β tended to show an inverse correlation or showed no significant relationship to all these parameters. Il-1β was measurable only in a limited number of samples. IL-1Ra showed a clear relationship to acute inflammatory events as well as to the different disease stages. Our data suggest a dissociation between IL-1Ra and sIL-1RII serum levels which may indicate that the two IL-1 binding proteins have different pathophysiological roles in HIV infection.     

Differential effects of tumour necrosis factor-α and interleukin-12 on isopentenyl pyrophosphate-stimulated interferon-γ production by cord blood Vγ9 T cells

Lower numbers of Vγ9Vδ2 T cells in cord blood (CB) than in adult peripheral blood (PB), as well as their impaired ability to produce interferon-γ (IFN-γ) in response to stimulation, are associated with functional deficiency in the immune system in newborns. In this study, we stimulated CB Vγ9 T cells with their T-cell receptor-specific ligand, isopentenyl pyrophosphate (IPP), plus exogenous costimulatory cytokines such as interleukin-2 (IL-2), IL-12 and tumour necrosis factor-α (TNF-α), which are known to play important roles in the activation of PB γδ T cells. Our data show that CB Vγ9 T cells are able to produce IFN-γ at levels comparable to PB Vγ9 T cells by the addition of TNF-α in the presence of IPP and IL-2; however, under the same culture conditions, IL-12 does not efficiently activate CB Vγ9 T cells to produce IFN-γ. The frequency of TNF-α receptor II-positive Vγ9T cells and the expression levels of TNF-α receptor II are similar in CB and PB; in contrast, the frequency of IL-12 receptor βI (IL-12RβI)-positive Vγ9T cells and expression levels of IL-12RβI are significantly lower in CB than PB. TNF-α but not IL-12 increases the expression of IL-2Rβ on CB Vγ9 T cells. These results provide new insights into the role of TNF-α in the activation of CB Vγ9 T cells.     

Interleukin-18 Induces Acute Biphasic Reduction in the Levels of Circulating Leukocytes in Mice

We investigated the acute hematological changes caused by interleukin-18 (IL-18) in mice. Intraperitoneal administration of IL-18 (2 μg/mouse) resulted in biphasic decreases in the number of leukocytes in the blood. The first phase of decrease occurred within 2 h of IL-18 administration and was followed by a transient increase at 5 h. The second phase of decrease occurred at around 6 h, reaching a nadir which lasted for more than 24 h. In mice deficient in inducible nitric oxide (NO) synthase, the first phase of reduction of leukocytes did not occur although the second phase of decrease was observed. In mice deficient in gamma interferon (IFN-γ) or in mice depleted of natural killer cells and incapable of producing IFN-γ, IL-18 had no effect on the number of circulating leukocytes. Levels of nitrite and/or nitrate in the serum were elevated within 2 h after administration of IL-18, reaching a peak at 4 h and then decreasing gradually to the basal level over a 24-h period of time. On the other hand, serum IFN-γ levels changed in a biphasic manner, reaching a peak at 2 h after IL-18 administration, followed by a decrease in the basal level and a second increase at 6 h. Levels of IL-18 receptor mRNAs also showed biphasic changes in correlation with the changes in serum IFN-γ levels. These results suggest that the changes in the leukocyte number following IL-18 administration are mediated by NO and IFN-γ, with NO being involved in the first phase of reduction and IFN-γ being involved in both phases.     

Cytokines as Mediators for or Effectors against Rotavirus Disease in Children

Rotavirus is the most common cause of severe gastroenteritis in young children, but the pathogenesis and immunity of this disease are not completely understood. To examine the host response to acute infection, we collected paired serum specimens from 30 children with rotavirus diarrhea and measured the levels of nine cytokines (interleukin-1β [IL-1β], IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, gamma interferon [IFN-γ], and tumor necrosis factor alpha [TNF-α]) using a microsphere-based Luminex Flowmetrix system. Patients with acute rotavirus infection had elevated median levels of seven cytokines in serum, and of these, the levels of three (IL-6, IL-10, and IFN-γ) were significantly (P < 0.05) higher than those in serum from control children without diarrhea. Patients with fever had significantly (P < 0.05) higher levels of IL-6 in serum than control children, and those with fever and more episodes of diarrhea had significantly (P < 0.05) higher levels of TNF-α than those without fever and with fewer episodes of diarrhea. We further demonstrated a negative association (P < 0.05) between the levels of IL-2 and the number of stools on the day on which the first blood sample was collected. Finally, patients with vomiting had significantly (P < 0.05) lower levels of IFN-γ than those without vomiting. Our pilot study provides evidence that the types and magnitudes of cytokine responses to rotavirus infection in children influence or reflect the clinical outcome of disease. These findings suggest that certain cytokines may play an important role in the pathogenesis of and the protection against rotavirus disease in children and, consequently, may provide directions and insights that could prove critical to the prevention or treatment of this important disease.     

A shedding soluble form of interleukin-17 receptor D exacerbates collagen-induced arthritis through facilitating TNF-α-dependent receptor clustering

Rheumatoid arthritis (RA) is exacerbated by TNF-alpha signaling. However, it remains unclear whether TNF-α-activated TNFR1 and TNFR2 are regulated by extracellular factors. Here, we showed that soluble glycosylated interleukin-17 receptor D (sIL-17RD), which was produced by proteolytic cleavage, enhanced TNF-α-induced RA. We revealed that IL-17RD shedding was induced by the proteolytic enzyme TACE and enhanced by TNF-α expression in macrophages. Intriguingly, sIL-17RD was elevated in the sera of arthritic mice and rats. Recombinant sIL-17RD significantly enhanced the TNF-α-induced proinflammatory response by promoting TNF-α-TNFR–sIL-17RD complex formation and receptor clustering, leading to the accelerated development of collagen-induced arthritis. Our observations revealed that ectodomain shedding of IL-17RD occurred in RA to boost the TNF-α-induced inflammatory response. Targeting sIL-17RD may provide a new strategy for the therapy of RA.     

Serum Cytokine Responses during Acute Human Granulocytic Ehrlichiosis

Human granulocytic ehrlichiosis (HGE) is caused by obligate intracellular bacteria in the Ehrlichia phagocytophila group. The disease ranges from subclinical to fatal. We speculated that cell-mediated immunity would be important for recovery from and potentially in the clinical manifestations of HGE; thus, serum tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), gamma interferon (IFN-γ), IL-10, and IL-4 concentrations were studied. IFN-γ (1,035 ± 235 pg/ml [mean ± standard error of the mean]) and IL-10 (118 ± 46 pg/ml) concentrations were elevated in acute-phase sera versus convalescent sera and normal subjects (P≤0.013 and P≤0.018, respectively). TNF-α, IL-1β, and IL-4 levels were not elevated. Cytokine levels in severely and mildly affected patients were not different. HGE leads to induction of IFN-γ-dominated cell-mediated immunity associated with clinical manifestations, recovery from infection, or both.     

Coexistent Malnutrition Is Associated with Perturbations in Systemic and Antigen-Specific Cytokine Responses in Latent Tuberculosis Infection

Malnutrition, as defined by low body mass index (BMI), is a major risk factor for the development of active tuberculosis (TB), although the biological basis underlying this susceptibility remains poorly characterized. To verify whether malnutrition affects the systemic and antigen-specific cytokine levels in individuals with latent TB (LTB), we examined circulating and TB antigen-stimulated levels of cytokines in individuals with LTB and low BMI (LBMI) and compared them with those in individuals with LTB and normal BMI (NBMI). Coexistent LBMI with LTB was characterized by diminished circulating levels of type 1 (gamma interferon [IFN-γ] and tumor necrosis factor alpha [TNF-α]), type 2 (interleukin-4 [IL-4]), type 17 (IL-22), and other proinflammatory (IL-1α, IL-1β, and IL-6) cytokines but elevated levels of other type 2 (IL-5 and IL-13) and regulatory (IL-10 and transforming growth factor beta [TGF-β]) cytokines. In addition, LBMI with LTB was associated with diminished TB antigen-induced IFN-γ, TNF-α, IL-6, IL-1α, and IL-1β levels. Finally, there was a significant positive correlation between BMI values and TNF-α and IL-1β levels and a significant negative correlation between BMI values and IL-2, IL-10, and TGF-β levels in individuals with LTB. Therefore, our data reveal that latent TB with a coexistent low BMI is characterized by diminished protective cytokine responses and heightened regulatory cytokine responses, providing a potential biological mechanism for the increased risk of developing active TB.     

Sputum Cytokine Levels in Patients with Pulmonary Tuberculosis as Early Markers of Mycobacterial Clearance

Sputum and serum from patients with active pulmonary tuberculosis (TB), healthy purified protein derivative-positive adults, and patients with bacterial pneumonia were collected to simultaneously assess local immunity in the lungs and peripheral blood. To determine whether cytokine profiles in sputum from TB patients and control subjects were a reflection of its cellular composition, cytospin slides were prepared in parallel and assessed for the presence of relative proportions of epithelial cells, neutrophils, macrophages, and T cells. Gamma interferon (IFN-γ) in sputum from TB patients was markedly elevated over levels for both control groups. With anti-TB therapy, IFN-γ levels in sputum from TB patients decreased rapidly and by week 4 of treatment were comparable to those in sputum from controls. Further, IFN-γ levels in sputum closely followed mycobacterial clearance. Although detected at fourfold-lower levels, IFN-γ immunoreactivities in serum followed kinetics in sputum. TNF-α, interleukin 8 (IL-8) and IL-6 also were readily detected in sputum from TB patients at baseline and responded to anti-TB therapy. In contrast to IFN-γ, however, TNF-α and IL-8 levels also were elevated in sputum from pneumonia controls. These data indicate that sputum cytokines correlate with disease activity during active TB of the lung and may serve as potential early markers for sputum conversion and response to anti-TB therapy.     

Ambiguous Role of Interleukin-12 in Yersinia enterocolitica Infection in Susceptible and Resistant Mouse Strains

Endogenous interleukin-12 (IL-12) mediates protection against Yersinia enterocolitica in C57BL/6 mice by triggering gamma interferon (IFN-γ) production in NK and CD4⁺ T cells. Administration of exogenous IL-12 confers protection against yersiniae in Yersinia-susceptible BALB/c mice but exacerbates yersiniosis in resistant C57BL/6 mice. Therefore, we wanted to dissect the different mechanisms exerted by IL-12 during Yersinia infections by using different models of Yersinia-resistant and -susceptible mice, including resistant C57BL/6 mice, susceptible BALB/c mice, intermediate-susceptible wild-type 129/Sv mice, 129/Sv IFN-γ-receptor-deficient (IFN-γR^−/−) mice and C57BL/6 tumor necrosis factor (TNF) receptor p55 chain-deficient (TNFR p55^−/−) mice. IFN-γR^−/− mice turned out to be highly susceptible to infection by Y. enterocolitica compared with IFN-γR^+/+ mice. Administration of IL-12 was protective in IFN-γR^+/+ mice but not in IFN-γR^−/− mice, suggesting that IFN-γR-induced mechanisms are essential for IL-12-induced resistance against yersiniae. BALB/c mice could be rendered Yersinia resistant by administration of anti-CD4 antibodies or by administration of IL-12. In contrast, C57BL/6 mice could be rendered more resistant by administration of transforming growth factor β (TGF-β). Furthermore, IL-12-triggered toxic effects in C57BL/6 mice were abrogated by coadministration of TGF-β. While administration of IL-12 alone increased TNF-α levels, administration of TGF-β or TGF-β plus IL-12 decreased both TNF-α and IFN-γ levels in Yersinia-infected C57BL/6 mice. Moreover, IL-12 did not induce toxicity in Yersinia-infected TNFR p55^−/− mice, suggesting that TNF-α accounts for IL-12-induced toxicity. Taken together, IL-12 may induce different effector mechanisms in BALB/c and C57BL/6 mice resulting either in protection or exacerbation. These results are important for understanding the critical balance of proinflammatory and regulatory cytokines in bacterial infections which is decisive for beneficial effects of cytokine therapy.     

Expression of Regulatory T Cells in Jejunum,Colon, and Cervical and Mesenteric Lymph Nodes of Dogs Naturally Infected with Leishmania infantum

Using flow cytometry, we evaluated the frequencies of CD4⁺ and CD8⁺ T cells and Foxp3⁺ regulatory T cells (Tregs) in mononuclear cells in the jejunum, colon, and cervical and mesenteric lymph nodes of dogs naturally infected with Leishmania infantum and in uninfected controls. All infected dogs showed chronic lymphadenitis and enteritis. Despite persistent parasite loads, no erosion or ulcers were evident in the epithelial mucosa. The colon harbored more parasites than the jejunum. Frequencies of total CD4⁺, total Foxp3, and CD4⁺ Foxp3⁺ cells were higher in the jejunum than in the colon. Despite negative enzyme-linked immunosorbent assay (ELISA) serum results for cytokines, levels of interleukin-10 (IL-10), gamma interferon (IFN-γ), transforming growth factor beta (TGF-β), and tumor necrosis factor alpha (TNF-α) were higher in the jejunum than in the colon for infected dogs. However, IL-4 levels were higher in the colon than in the jejunum for infected dogs. There was no observed correlation between clinical signs and histopathological changes or immunological and parasitological findings in the gastrointestinal tract (GIT) of canines with visceral leishmaniasis. However, distinct segments of the GIT presented different immunological and parasitological responses. The jejunum showed a lower parasite load, with increased frequencies and expression of CD4, Foxp3, and CD8 receptors and IL-10, TGF-β, IFN-γ, and TNF-α cytokines. The colon showed a higher parasite load, with increasing expression of IL-4. Leishmania infantum infection increased expression of CD4, Foxp3, IL-10, TGF-β, IFN-γ, and TNF-α and reduced CD8 and IL-4 expression in both the jejunum and the colon.     

Pentoxifylline Inhibits Superantigen-Induced Toxic Shock and Cytokine Release

Tumor necrosis factor alpha (TNF-α) is a critical cytokine that mediates the toxic effects of bacterial superantigens like staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin 1 (TSST-1). Pentoxifylline, an anti-inflammatory agent that inhibits endotoxemia and lipopolysaccharide (LPS)-induced release of TNF-α, was tested for its ability to inhibit SEB- and TSST-1-induced activation of human peripheral blood mononuclear cells (PBMCs) in vitro and toxin-mediated shock in mice. Stimulation of PBMCs by SEB or TSST-1 was effectively blocked by pentoxifylline (10 mM), as evidenced by the inhibition of TNF-α, interleukin 1β (IL-1β), gamma interferon (IFN-γ), and T-cell proliferation. The levels of TNF-α, IL-1α, and IFN-γ in serum after an SEB or TSST-1 injection were significantly lower in mice given pentoxifylline (5.5 mg/animal) versus control mice. Additionally, pentoxifylline diminished the lethal effects and temperature fluctuations elicited by SEB and TSST-1. Thus, in addition to treating endotoxemias, the cumulative in vitro and in vivo data suggest that pentoxifylline may also be useful in abrogating the ill effects of staphylococcal enterotoxins and TSST-1.