Innate immune responses against Cryptosporidium parvum infection

Cryptosporidium parvum infects intestinal epithelial cells and is commonly the parasite species involved in mammalian cryptosporidiosis, a major health problem for humans and neonatal livestock. In mice, immunologically mediated elimination of C. parvum requires CD4⁺ T cells and IFN‐γ. However, innate immune responses also have a significant protective role in both adult and neonatal mice. NK cells and IFN‐γ have been shown to be important components in immunity in T and B cell‐deficient mice, but IFN‐γ‐dependent resistance has also been demonstrated in alymphocytic mice. Epithelial cells may play a vital role in immunity as once infected these cells have increased expression of inflammatory chemokines and cytokines and demonstrate antimicrobial killing mechanisms, including production of NO and antimicrobial peptides. Toll‐like receptors facilitate the establishment of immunity in mice and are involved in the development of inflammatory responses of infected epithelial cells and also dendritic cells.     

Toll样受体介导的抗乙型肝炎病毒的固有免疫

在抗感染免疫过程中,特别是病毒感染早期,固有免疫应答具有重要意义。固有免疫系统发挥防御作用的关键是对病原体的识别,Toll样受体（TLRs）作为固有免疫的重要组分之一,通过配体识别、信号转导、免疫分子活化等环节启动固有免疫并调节获得性免疫。本文就近年来TLRs介导的固有免疫抗乙型肝炎病毒感染的作用和相关的免疫调节机制进行综述     

Local immune responses in human tuberculosis: learning from the site of infection

Host-pathogen interactions in tuberculosis should be studied at the disease site because Mycobacterium tuberculosis is predominately contained in local tissue lesions. Although M. tuberculosis infection involves different clinical forms of tuberculosis, such as pulmonary tuberculosis, pleural tuberculosis, and lymph node tuberculosis, most studies of human tuberculosis are performed using cells from the peripheral blood, which may not provide a proper reflection of the M. tuberculosis-specific immune responses induced at the local site of infection. A very low proportion of M. tuberculosis-specific effector T cells are found in the blood compared with the infected tissue, and thus there may be considerable differences in the cellular immune response and regulatory mechanisms induced in these diverse compartments. In this review, we discuss differences in the immune response at the local site of infection compared with the peripheral circulation. The cell types and immune reactions involved in granuloma formation and maintenance as well as the in situ technologies used to assess local tuberculosis pathogenesis are also described. We need to strengthen and improve the exploratory strategies used to dissect immunopathogenesis in human tuberculosis with the aim to accelerate the implementation of relevant research findings in clinical practice.     

HBV DNA vaccine with adjuvant cytokines induced specific immune responses against HBV infection

AIM: To seek for an effective method to improve the immuneresponses induced by DNA vaccine expressing HBV surfaceantigen (pCR3.1-S) in Balb/c mice (H-2d).METHODS: The pCR3.1-S plasmid and the eukaryoticexpression vectors expressing murine IL-2 (pDOR-IL-2) orIL-12 (pWRG3169) were injected into mice subcutaneously.The immune responses to pCR3.1-S and the adjuvant effectof the cytokines plasmid were studied. Meanwhile the effectof pCR3.1-S on anti-translated subcutaneous tumor of P815mastocytoma cells stably expressing HBsAg (P815-HBV-S)was also studied. Anti-HBs in serum was detected by enzyme-linked immunoadsordent assay (ELISA) and HBsAg specificcytotoxic T lymphocytes (CTLs) activity was measured by 51Crrelease assay. After three weeks of DNA immunization, thecells of P815-HBV-S were inoculated into mice subcutaneouslyand the tumor growth was measured every five days. Thesurvival rate and living periods of mice were also calculated.RESULTS: After 8 wk DNA immunization, the ,4 450 nmvalues of sera in mice immunized with pCR3.1, pCR3.1-Sand pCR3.1-S codeliveried with IL-2 or IL-12 plasmids were0.03±0.01, 1.24±0.10, 1.98±0.17 and 1.67±0.12respectively. Data in mice codeliveried pCR3.1-S with IL-2or IL-12 plasmids were significantly higher than that of miceinjected pCR3.1 or pCR3.1-S only. The HBsAg specific CTLactivities in mice coinjected with pCR3.1-S and IL-2 or IL-12 eukaryotic expression vectors were (61.9±7.1) % and(73.3±8.8) %, which were significantly higher than that ofmice injected with pCR3.1 (10.1±2.1) % or pCR3.1-S (50.5±6.4) %. The HBsAg specific CTL activities in mice injectedwith pCR3.1, pCR3.1-S, pCR3.1-S combined with IL-2 or IL-12 eukaryotic expression vectors decreased significantly to(3.2±0.8) %, (10.6±1.4) %, (13.6±1.3) % and (16.9±2.3)% respectively after the spleen cells were treated by anti-CD8+ monoclonal antibody, but presented no significantchange to anti-CD4+ monoclonal antibody or unrelated tomonoclonal antibody. The HBV-S DNA vaccine (pCR3.1-S)could evidently inhibit the tumor growth, prolong the survivalperiod of mice and improve the survival rate of mice andthese effects could be improved by IL-12 gene codeliveried.CONCLUSION: HBV DNA vaccine has a strong antigenicityin humoral and cellular immunities, which can be promotedby plasmid expressing IL-2 or IL-12. CD8+ cells executedthe CTL activities. DNA vaccine may be useful for bothprophylaxis and treatment of HBV infection.     

HBV DNA vaccine with adjuvant cytokines induced specific immune responses against HBV infection

AIM: To seek for an effective method to improve the immuneresponses induced by DNA vaccine expressing HBV surfaceantigen (pCR3.1-S) in Balb/c mice (H-2d).METHODS: The pCR3.1-S plasmid and the eukaryoticexpression vectors expressing murine IL-2 (pDOR-IL-2) orIL-12 (pWRG3169) were injected into mice subcutaneously.The immune responses to pCR3.1-S and the adjuvant effectof the cytokines plasmid were studied. Meanwhile the effectof pCR3.1-S on anti-translated subcutaneous tumor of P815mastocytoma cells stably expressing HBsAg (P815-HBV-S)was also studied. Anti-HBs in serum was detected by enzyme-linked immunoadsordent assay (ELISA) and HBsAg specificcytotoxic T lymphocytes (CTLs) activity was measured by 51Crrelease assay. After three weeks of DNA immunization, thecells of P815-HBV-S were inoculated into mice subcutaneouslyand the tumor growth was measured every five days. Thesurvival rate and living periods of mice were also calculated.RESULTS: After 8 wk DNA immunization, the ,4 450 nmvalues of sera in mice immunized with pCR3.1, pCR3.1-Sand pCR3.1-S codeliveried with IL-2 or IL-12 plasmids were0.03±0.01, 1.24±0.10, 1.98±0.17 and 1.67±0.12respectively. Data in mice codeliveried pCR3.1-S with IL-2or IL-12 plasmids were significantly higher than that of miceinjected pCR3.1 or pCR3.1-S only. The HBsAg specific CTLactivities in mice coinjected with pCR3.1-S and IL-2 or IL-12 eukaryotic expression vectors were (61.9±7.1) % and(73.3±8.8) %, which were significantly higher than that ofmice injected with pCR3.1 (10.1±2.1) % or pCR3.1-S (50.5±6.4) %. The HBsAg specific CTL activities in mice injectedwith pCR3.1, pCR3.1-S, pCR3.1-S combined with IL-2 or IL-12 eukaryotic expression vectors decreased significantly to(3.2±0.8) %, (10.6±1.4) %, (13.6±1.3) % and (16.9±2.3)% respectively after the spleen cells were treated by anti-CD8+ monoclonal antibody, but presented no significantchange to anti-CD4+ monoclonal antibody or unrelated tomonoclonal antibody. The HBV-S DNA vaccine (pCR3.1-S)could evidently inhibit the tumor growth, prolong the survivalperiod of mice and improve the survival rate of mice andthese effects could be improved by IL-12 gene codeliveried.CONCLUSION: HBV DNA vaccine has a strong antigenicityin humoral and cellular immunities, which can be promotedby plasmid expressing IL-2 or IL-12. CD8+ cells executedthe CTL activities. DNA vaccine may be useful for bothprophylaxis and treatment of HBV infection.     

Reconstitution of immune responses to tuberculosis in patients with HIV infection who receive antiretroviral therapy

STUDY OBJECTIVE:s: To assess the restoration of immune responses to tuberculosis, as manifested by secretion of T-helper type 1 cytokines (interferon [IFN]-gamma, interleukin [IL]-12, and IL-2) and T-helper type 2 cytokines (IL-10), in HIV-positive patients who receive antiretroviral therapy (ART). DESIGN: Prospective cohort study. SETTING: University hospital. PATIENTS: Ten HIV-positive patients, all na?ve to ART and all about to start ART for clinical indications, and 11 healthy, HIV-negative control subjects. INTERVENTIONS: Assessment of T-cell proliferation and cytokine production after administration of ART to patients with HIV infection. MEASUREMENTS AND RESULTS: All patients had a negative tuberculin skin test result at baseline and were anergic. Highly active ART reduced the viral load to very low levels in all patients within a short time after starting therapy. Blood samples were drawn every 2 months after starting therapy, and continued for 1 year while the patients continued to receive ART. There were trends toward increased proliferation of peripheral blood mononuclear cells (PBMCs) in response to Mycobacterium tuberculosis-specific stimuli, but these were delayed until several months of ART had elapsed. Similar trends were noted in relation to the secretion of IFN-gamma. Neither PBMC proliferation nor IFN-gamma secretion reached levels seen in healthy control subjects. No consistent trends in IL-2, IL-10, or IL-12 production were noted. CONCLUSION: ART restores immune responses to M tuberculosis, although this restoration is delayed and does not reach levels seen in healthy, HIV-negative control subjects. These results may explain in part the phenomenon of paradoxic reactions to antituberculosis therapy in patients with HIV infection. A larger study in which patients are followed up for a longer period of time will allow the magnitude and timing of this reconstitution to be more precisely defined.     

A co‐infection with two gastrointestinal nematodes alters host immune responses and only partially parasite dynamics

Given their global distribution and abilities to persist in the host, helminths can play a crucial role in affecting risk of infections by increasing individual variation in infection. Helminth co‐infections are of particular interest because by altering host immune responses, they can modify host susceptibility and thus intensity and transmission of other parasites/pathogens. The dynamics of co‐infection were examined using two helminths of the European rabbit. Individuals were simultaneously challenged with a primary dose of both parasites, and changes in intensity were examined in relation to local and systemic immune responses. Both helminths persisted in co‐infected rabbits; however, contrasting dynamics and immune responses were observed. Graphidium strigosum intensity was high throughout the co‐infection, while Trichostrongylus retortaeformis intensity decreased but was not completely cleared. A Th2 response was observed against G. strigosum, while a mixed Th1/Th2 profile was found to T. retortaeformis. A comparison with our previous work on single infections showed that G. strigosum intensity was higher in co‐infected than single infected hosts, while T. retortaeformis showed no significant changes. Differences were also observed in the cytokine profiles, blood cell concentrations and antibody trends. Overall, host variability during helminth co‐infections can be generated by significant differences in immune responses and/or parasite dynamics.     

Rifampin and cell-mediated immune responses in tuberculosis.

To estimate the potential adverse consequences of rifampin therapy on cell-mediated immunity in tuberculosis, we measured in vitro lymphocyte responses to phytohemagglutinin, concanavalin A, pokeweed mitogen, and in vitro and in vivo responses to purified protein derivative tuberculin. Thirty-seven patients treated with therapeutic combinations containing rifampin were compared with 13 persons who had never received the drug. After initial improvement, responses to phytohemagglutinin became depressed in patients receiving rifampin for periods of 4 to 24 months. No significant changes were noted in lymphocyte responses to concanavalin A or pokeweed mitogen. In vitro and in vivo responses to purified protein derivative tuberculin were not altered. Because a favorable therapeutic outcome was achieved in all subjects, we concluded that rifampin does not have clinically significant immunosuppressive activity.     

Broadening our view of protective antibody responses against HIV

Upon viral exposure, antibodies serve as a first line of defense and can act by preventing infection or reducing the viral burden. The ability of antibodies to confer protection against HIV has been demonstrated by several studies using the passive transfer of neutralizing antibodies in the non-human primate challenge model. Therefore, efforts have been made to induce a similarly protective humoral immune response by vaccination with antigens derived from HIV. Thus far, the results have been disappointing. Humoral immune responses elicited via vaccination display activities that are generally much less potent and broad as compared to those induced during natural infection. However, recently there have been increased efforts to systematically identify and compare the epitopes potentially critical to the generation of protective antibody responses in the hope that this will lead to improved strategies and superior immunogen design. As a critical part of this process, novel methods to monitor protective antibody responses will also need to be vigorously explored and improved, then validated in both preclinical and clinical settings.     

A theoretical framework for immune responses and predisposition to helminth infection

Many field studies of human helminth infections have reported a positive correlation between parasite burdens and the rate of re-establishment of infection following chemotherapy, i.e., predisposition. Some studies have also reported the relationships between re-establishment and exposure and immune responses. The interpretation of these data is made difficult by the complexity of the underlying immunoepidemiological processes. In this paper, simple mathematical models are used to explore expected patterns, especially in relation to host age. These patterns are determined by rates of infection, parasite life expectancy, the level of immunological responsiveness, the duration of immunological memory, and may be greatly affected by the immunogenic roles of different parasite stages. In general, acquired immunity is predicted to reduce the degree of predisposition. This reduction is age-dependent and may generate ‘negative predisposition’ in some age classes. Age-dependent reductions in the correlation between re-establishment and exposure are also predicted. The correlation between re-establishment and protective immune responses is also predicted to be age-dependent, but may remain positive for all ages despite significant acquired immunity. The results suggest that great care is needed in the interpretation of immunoepidemiological data from treatment-reinfection studies.     

Mycobacterium tuberculosis Rv2224c modulates innate immune responses

Tuberculosis remains a major global health problem that kills up to 2 million people annually. Central to the success of Mycobacterium tuberculosis (Mtb) as a pathogen is its ability to evade host immunity and to establish a chronic infection. Although its primary intracellular niche is within macrophages, the underlying molecular mechanisms are poorly understood. Here we show that Rv2224c, a cell envelope-associated predicted protease, is critical for Mtb virulence. Disruption of Rv2224c led to prolonged survival of infected mice and highly reduced lung pathology. Absence of Rv2224c enhanced host innate immune responses, compromised the intracellular survival of Mtb in macrophages, and increased its susceptibility to lysozyme. We provide insights into the molecular basis for Rv2224c function by showing that Rv2224c activity promotes processing and extracellular release of the Mtb protein, GroEL2. Inhibition of Rv2224c and its targets offers opportunities for therapeutic interventions and immune-modulatory strategies.     

Human in vitro immune responses to Mycobacterium tuberculosis.

SETTING: T helper cells can be divided into 2 subsets on the basis of their cytokine generation. T helper 1 cells secreting gamma interferon and interleukin 2 appear to be more prominent in patients with limited tuberculous disease. OBJECTIVE: The purpose of this study was to evaluate human T helper cell immune responses to mycobacterial antigens in vitro and correlate these with the clinical features of patients with tuberculous infection or disease. DESIGN: We studied 51 subjects and 11 controls who were grouped according to disease involvement as follows: 1) Mantoux negative, BCG negative, no disease; 2) Mantoux positive, no disease; 3) localized extrapulmonary; 4) healed pulmonary; 5) active pulmonary; and 6) miliary/disseminated. Peripheral blood mononuclear cells were cultured with PHA, PPD or Tetanus Toxoid, proliferation assessed and the supernatant analysed using an ELISA for IFN gamma. ELISA was also used to measure M. tuberculosis specific antibodies in the serum. RESULTS: Mantoux size correlated with PPD proliferation r = 0.5, P = 0.005 and gamma IFN production r = 0.36, P < 0.01. All groups produced abundant gamma IFN although there was a trend toward higher production in groups 3 and 4. M. tuberculosis specific IgA (P = 0.003) and IgG1 (P = 0.002) was higher in groups 5 and 6. Those patients with limited disease (groups 2-4) had significantly lower levels of IgG4 than patients with severe disease (groups 5 & 6) (P < 0.02). CONCLUSION: In conclusion patients with healed or extrapulmonary disease have immune responses in vitro suggestive of a TH1 (cell mediated immune) response, whereas patients with miliary/disseminated disease have antibody production suggestive of a TH2 response, together with high gamma IFN production. Both TH1 and TH2 responses may be necessary for host protection if there is a high bacillary load.     

Differential T cell responses against DosR-associated antigen Rv2028c in BCG-vaccinated populations with tuberculosis infection

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Microbiota regulates immune defense against respiratory tract influenza A virus infection

Although commensal bacteria are crucial in maintaining immune homeostasis of the intestine, the role of commensal bacteria in immune responses at other mucosal surfaces remains less clear. Here, we show that commensal microbiota composition critically regulates the generation of virus-specific CD4 and CD8 T cells and antibody responses following respiratory influenza virus infection. By using various antibiotic treatments, we found that neomycin-sensitive bacteria are associated with the induction of productive immune responses in the lung. Local or distal injection of Toll-like receptor (TLR) ligands could rescue the immune impairment in the antibiotic-treated mice. Intact microbiota provided signals leading to the expression of mRNA for pro-IL-1β and pro-IL-18 at steady state. Following influenza virus infection, inflammasome activation led to migration of dendritic cells (DCs) from the lung to the draining lymph node and T-cell priming. Our results reveal the importance of commensal microbiota in regulating immunity in the respiratory mucosa through the proper activation of inflammasomes.     

A consensus view of protein dynamics

The dynamics of proteins in aqueous solution has been investigated through a massive approach based on "state of the art" molecular dynamics simulations performed for all protein metafolds using the four most popular force fields (OPLS, CHARMM, AMBER, and GROMOS). A detailed analysis of the massive database of trajectories (>1.5 terabytes of data obtained using approximately 50 years of CPU) allowed us to obtain a robust-consensus picture of protein dynamics in aqueous solution.     

Human immune recognition-based multicomponent subunit vaccines against tuberculosis.

The cell-mediated immune response, with its shift in favour of type-1 over type-2 T-helper cell immune response, is generally regarded as essential to protection against mycobacterial infections. The aim of this study was to evaluate the protective potential of two multicomponent subunit vaccines (MSV-1 and MSV-2) against tuberculosis (TB) based on human immune recognition. MSV-1 consisted of five immunodominant antigens (TB10.4, early secretory antigenic target (ESAT)-6, culture filtrate protein (CFP)-8, CFP-10 and CFP-15) selected from a group of polypeptides, which induced a predominant T-cell response in immune human subjects, whereas MSV-2 consisted of antigens (CFP-11, CFP-21, CFP-22.5, Mycobacterium tuberculosis protein (MPT)-64 and CFP-31) selected from a group of polypeptides which induced a subdominant T-cell response along with the antibody response. Both of these sets of polypeptides were extensively recognised in healthy individuals with significant interferon gamma release compared to the diseased population. In C57BL/6J mice, at the level of the lungs, the order of protective efficacy for the test vaccines was: bacille Calmette-Guerin (BCG)>MSV-2>MSV-1. The protective efficacy of MSV-1 was found to be significantly less than that of MSV-2 and BCG at the level of spleen, whereas that of MSV-2 was comparable to that of BCG. The results of this study indicate that high T-helper cell type 1 response-inducing polypeptides selected on the basis of human immune recognition do not necessarily impart protection during vaccination experiments.     

Streptococcal immune responses in nephritis after skin infection

Detailed comparisons were drawn between similar numbers of patients with acute glomerulonephritis (101), their infected siblings (97) and patients with uncomplicated impetigo (107), all of whom had Streptococcal pyoderma. Hyperimmune antiDNAse B responses in patients with acute glomerulonephritis were most impressive, and were greater in frequency and magnitude than were antistreptolysin O responses among all patients with pyoderma. AntiDNAse B titers were elevated in over 90 per cent of patients with acute glomerulonephritis. In contrast, only half of those patients with acute glomerulonephritis had an elevated antistreptolysin O. Mean antiDNAse B titers in all patient groups were significantly higher than those in uninfected controls. These data are the first unequivocal evidence that the Streptococcal immune response in patients with acute glomerulonephritis is significantly greater than that in comparable groups of infected patients.Serial tests in convalescent patients with pyoderma and acute glomerulonephritis revealed that antiDNAse B titers rose more often and persisted longer than did antistreptolysin O titers. The nature of the Streptococcal immune response is related to the site of infection. Neither antistreptolysin O nor antiDNAse B responses in patients with skin infection and acute glomerulonephritis were influenced by Streptococcal carriage in the throat, which likely represented colonization secondary to pyoderma.The superiority of the antiDNAse B test for serologic study of pyoderma is evident. A general unresponsiveness on the part of the host cannot be invoked to explain the antistreptolysin O findings. Neither do our data support the hypothesis that the antistreptolysin O response is a function of infecting serotype. Local inhibition of the antigenicity of streptolysin O at the site of the skin infection, or other more general mechanisms of inhibition of streptolysin O antigenicity, remain attractive hypotheses to be explored.As a result of our observations, the role of a hyperimmune mechanism in the pathogenesis of acute glomerulonephritis as well as rheumatic fever should be considered. The strikingly high antibody titers in acute glomerulonephritis, particularly in young children, suggest that attack rates are related to the magnitude of the immune response.     

Stage-specific immune responses in human Necator americanus infection

We describe how hookworms interact with their human hosts by comparing lymphocyte phenotyping, proliferative responses, and cytokine and chemokine secretion patterns in adults who are either mono-infected with Necator americanus or egg-negative controls resident in an area of high transmission in Brazil. Cellular immune responses against crude hookworm antigen extracts from different developmental stages were evaluated simultaneously. Principal component analysis (PCA) was used to reduce the standardized immune responses. Random effects multivariate regression was then used to investigate whether principal components (PC) differ between the two groups once potential confounders and effect modifiers have been accounted for. Although hookworm patients had reduced percentages of T and B cells, they had higher levels of activated CD4(+) T and CD19(+) B cells. This state of 'immune activation' coincided with lower proliferative responses, especially to third-stage larval antigen. Cytokine levels in mono-infected adults were also lower and characterized by a mixed Th1/Th2-type profile. Excretory/secretory antigen from adult worms was a potent modulator of the immune response, resulting in diminished TNF-alpha and IL-10 secretion in peripheral blood mononuclear cells (PBMC) from hookworm infected patients. We propose that the longevity of hookworms in their human hosts results from a stage-specific, down-modulation of the immune response.