Shiguang Huang

CD4+ T Cells in the Pathogenesis of Murine Ocular Toxoplasmosis

ABSTRACT The role of CD4+ T cells in the pathogenesis of ocular toxoplasmosis was investigated in murine models utilizing inbred C57BL/6 mice deficient either in CD4+, CD8+, or B cells (μMT). Severe necrosis and inflammation with replicating parasites were observed in the eyes of control mice after primary ocular infection, and near-normal histology with few tachyzoites was observed in the eyes of mice immunized intraperitoneally with the avirulent ts-4 strain followed by intraocular challenge with the RH strain of Toxoplasma gondii. In contrast, mild inflammation without evidence of necrosis associated with increased parasite burdens were observed in the eyes of CD4 knockout (KO) mice after both primary ocular infection and challenge with RH tachyzoites. CD8 KO mice, as well as μMT mice, demonstrated increased ocular necrosis in response to either primary ocular infection or challenge. The parasite burden was increased in the eyes of both CD8 KO and μMT mice in which the parasite load was even higher. As expected, there were no increases in the levels of immunoglobulin G in serum or aqueous humor in μMT mice, and there was no increase in the levels of gamma interferon and tumor necrosis factor alpha in the sera of CD4 KO mice after both infection and challenge. These results suggest that the ocular inflammatory response to the parasite is mediated primarily by the CD4+-T-cell response. CD8+ T cells and B cells may play an important role in limiting tachyzoite proliferation in the eyes. Mice deficient in CD8+ CD4+ T cells or B cells exhibit diminished vaccine-induced resistance and increased ocular parasite burden after challenge.

Experimental Ocular Toxoplasmosis in Genetically Susceptible and Resistant Mice

ABSTRACT Genetic factors determining the pathogenesis and course of ocular toxoplasmosis are poorly understood. In this study, we explored the development of experimental ocular pathogenesis in genetically dissimilar mice infected with either the RH strain, the PLK strain, or the immunodominant surface antigen 1 (SAG1 [P30])-deficient mutant of the RH strain of Toxoplasma gondii. At 11 days postinfection, ocular infection of C57BL/6 mice with all of the strains of parasites resulted in severe inflammatory lesions and high numbers of parasites in eye tissue; less severe ocular lesions at earlier histopathology and prolonged survival were observed in this mouse strain infected with either the major surface antigen 1-deficient SAG1−/− strain or the less virulent PLK strain compared with RH infection. In contrast, both BALB/c and CBA/J mice had less severe lesions and low numbers of parasites in their eye tissue, and infection developed into the chronic stage in these mice. There were significantly higher serum levels of gamma interferon and tumor necrosis factor alpha in C57BL/6 mice than in BALB/c and CBA/J mice following ocular infection. These observations confirm earlier reports on systemic immunity to these parasites that the route of Toxoplasma infection markedly influences survival of mice. Our data indicate that genetic factors of the host as well as the parasite strain are critical in determining susceptibility to experimental ocular toxoplasmosis in murine models.

Meta-analysis of prevention and treatment of toxoplasmic encephalitis in HIV-infected patients

Toxoplasmic encephalitis (TE) is one of the most common central nervous system (CNS) opportunistic infections in HIV-infected patients. It can be prevented and treated through drug regimen. However, drugs have serious adverse effects sometimes. The purpose of this review is to determine the most effective therapy for TE in HIV-infected patients. Different primary prophylaxis and treatment regimens have been compared with regard to episodes of TE, clinical response, morbidity, and serious adverse events. In September 2012, we searched PubMed, Google Scholar, EMBASE, and CENTRAL (the Cochrane Central Register of Controlled Trials) database for randomized and quasi-randomized controlled trials of any drug regimen for primary prophylaxis and treatment of TE in HIV-infected patients. We independently extracted data and assessed eligibility and risk of bias using a standardized data collection form, and resolved any disagreement through discussion. We combined dichotomous outcomes using odds ratio (OR), presenting with 95% confidence interval (CI). Eleven trials were found to meet the inclusion criteria. Six trials compared trimethoprim-sulfamethoxazole (TMP-SMX) with dapsone-pyrimethamine (D-P) were analyzed together for the outcome of episodes of TE, morbidity, and serious adverse events. The two treatment arms did not differ for episodes of TE (OR=0.98; 95% CI: 0.48-2.00). Compared with D-P, TMP-SMX showed a beneficial trend in terms of mortality despite a lack of statistical significance (OR=0.75; 95% CI: 0.53-1.06). However, TMP-SMX is still associated with substantial toxicity and intolerance (OR=1.47; 95% CI: 0.91-2.38). Three trials compared pyrimethamine-sulfadiazine (P-S) with pyrimethamine-clindamycin (P-C) were analyzed together for the outcome of clinical response, morbidity, and serious adverse events. Compared with P-C, P-S showed a beneficial trend in terms of clinical response (OR=1.63; 95% CI: 1.05-2.51); P-S also showed a beneficial trend in terms of mortality despite a lack of statistical significance (OR=0.66; 95% CI: 0.37-1.17). However, P-S is still associated with substantial toxicity and intolerance (OR=3.08; 95% CI: 1.82-5.24). Two trials compared P-S with TMP-SMX were analyzed together for the outcome of clinical response, morbidity, and serious adverse events. The two treatment arms did not differ for clinical response (OR=0.90; 95% CI: 0.39-2.06). Compared with TMP-SMX, P-S showed a beneficial trend in terms of mortality despite a lack of statistical significance (OR=0.12; 95% CI: 0.01-1.39). However, P-S is still associated with substantial toxicity and intolerance (OR=2.91; 95% CI: 0.99-8.55). The available evidence fails to identify any one superior regimen for the primary prophylaxis and treatment of TE. The choice of therapy will often be directed by available therapy. Although current evidence does not allow a definitive recommendation, administration of TMP-SMX for primary prophylaxis and treatment of TE in patients with HIV infection is consistent with the available data.

Interleukin-10 and Pathogenesis of Murine Ocular Toxoplasmosis

ABSTRACT To understand the role of interleukin-10 (IL-10) in ocular toxoplasmosis, we compared C57BL/6 (B6) and BALB/c background mice lacking a functional IL-10 gene (IL-10−/−) and B6 transgenic mice expressing IL-10 under the control of the IL-2 promoter. Increased cellular infiltration and necrosis were observed in the eye tissue of IL-10−/− mice of both the B6 and BALB/c backgrounds with associated changes in the levels of cytokines in serum. In contrast, there was no evidence of necrosis in the eye tissue from IL-10 transgenic mice following parasite exposure. Our results demonstrate that IL-10 is important in the regulation of inflammation during acute ocular toxoplasmosis.

Evaluation of the adjuvant properties of Astragalus membranaceus and Scutellaria baicalensis GEORGI in the immune protection induced by UV-attenuated Toxoplasma gondii in mouse models

Human vaccines are not available and current anti-toxoplasma treatment is disappointing. To investigate the possible adjuvant effect of aqueous extracts obtained from medicinal herbs of Astragalus membranaceus (Am) and Scutellaria baicalensis GEORGI (Sb) on the immune response to Toxoplasma gondii in the mouse models induced by ultraviolet (UV)-attenuated T. gondii, this paper studies the possible vaccination strategies to help combat infections with Toxoplasma and looking towards developing new vaccine and approaches. We used UV-attenuated T. gondii (UV-T.g) of RH strain as a vaccine and the extracts of Am (AmE) and Sb (SbE) as adjuvant. Mice were infected by intraperitoneal (i.p.) injection of 10(2) RH tachyzoites alone (infected controls), infected and treated with AmE (T.g+AmE) and SbE (T.g+SbE), respectively; and mice immunized i.p. with UV-T.g alone, UV-T.g co-administrated with AmE (UV-T.g+AmE) or SbE (UV-T.g+SbE), and then challenged with T.g, respectively. The animal survival time, parasite burden in peritoneal lavage fluids, liver histopathological analysis, and levels of serum antibodies among the groups were compared after either infection or challenge. The results showed that, compared to infected controls, infected mice treated with AmE or SbE, or vaccinated mice and then challenged, had significantly prolonged survival time, decreased parasite burden, improved liver histopathological score, and increased Th1-type cellular immune response; furthermore, vaccinated mice co-administrated with AmE or SbE had even longer survival, lower parasite burden, lower liver histopathological score, and higher Th1 response after challenge. Our data demonstrated that the protective immunity of UV-attenuated T. gondii could be markedly enhanced by AmE or SbE co-administration, which suggests that both AmE and SbE may have the potential to be used as effective vaccine adjuvant.

Mast Cell Degranulation in Human Periodontitis

BACKGROUND Mast cells are tissue-resident immune cells that participate in a variety of allergic and inflammatory conditions. Limited attention has been given to the role of mast cells in periodontal diseases, and the effects of mast cell degranulation on the chronic stages of non-allergic inflammation, particularly in periodontitis, are not known. The present study analyzes the relationship between the mast cell degranulation and human periodontal disease progression. METHODS A total of 50 clinical specimens including moderate periodontitis (n = 17), advanced periodontitis (n = 18), and healthy control tissues (n = 15) were used in this study. All specimens were fixed in 10% buffered formalin and stained with hematoxylin and eosin for histopathology, with toluidine blue for identifying mast cells, and by immunohistochemistry for the expressions of mast cell tryptase in periodontal tissues. The total and degranulated mast cell densities (per high-power field) were quantified in the specimens. RESULTS Compared with healthy controls, there were significantly increased both total and degranulated mast cell densities in human moderate (P <0.01) and advanced (P <0.01) periodontitis groups by toluidine blue staining, and there were significantly higher densities of both total and degranulated tryptase-positive mast cell subpopulation in the moderate periodontitis group (P <0.01) and even significantly higher subpopulation densities in the advanced periodontitis group by immunohistochemical staining, in which both total and degranulated mast cell densities were significantly higher in the advanced periodontitis group than those in the moderate periodontitis group (P <0.01) by both toluidine blue staining and immunohistochemical staining. There was significantly more severe periodontal inflammatory pathology in the advanced periodontitis group than in the moderate periodontitis group (P <0.01). CONCLUSION These findings indicate a significant correlation among tryptase-positive mast cell density, the degree of their degranulation, and the human periodontitis severity, and the results of this study further indicate that mast cell degranulation appears to be associated with human periodontal disease.

The Role of Psychologic Stress-Induced Hypoxia-Inducible Factor-1α in Rat Experimental Periodontitis

BACKGROUND Studies have shown that psychologic stress plays a significant role in the outcome of many diseases. The present study is designed to investigate the effect of stress on experimental ligature-induced periodontal disease in rats by means of a variable moderate chronic stress model. METHODS Sixty-six age-matched male Wistar rats of specific pathogen-free grade were randomly divided into four groups: 1) normal control group, naive rats; 2) experimental periodontitis group, received only silk ligatures at the gingival margins of the second maxillary molar; 3) stress-stimulation group, treated only with experimental stress conditions; and 4) experimental periodontitis plus stress-stimulation group (e.g., experimental groups also exposed to stress). Stress was imposed by means of restraint stress, cold-water immersion stress, and cat shock stress, which were all applied randomly. The rats were sacrificed at weeks 1, 4, 6, and 8 of the experiment. Attachment losses (AL) were measured by a specially made periodontal probe. The histopathologic changes of periodontia stained with hematoxylin and eosin were observed under a microscope. The expression of hypoxia-inducible factor-1α used to evaluate tissue hypoxic degree in periodontal tissues was tested by immunohistochemistry. RESULTS Our results show that there was no significant difference of AL among the normal control and the stress-stimulation groups (P >0.05); AL of the periodontitis plus stress-stimulation group was significantly higher than that of the experimental periodontitis group at weeks 4, 6, and 8 (P <0.01), and the hypoxia-inducible factor-1α expression scores of the periodontitis plus stress-stimulation group were significantly higher than those of the experimental periodontitis group at weeks 4, 6, and 8 (P = 0.0477). CONCLUSIONS Stress-stimulation may aggravate periodontitis by decreased tissue oxygenation in rats. We conclude that there is a correlation of periodontitis severity with psychologic stress and periodontal tissue hypoxia.

Genetic diversity of Plasmodium vivax population in Anhui province of China

BackgroundAlthough the numbers of malaria cases in China have been declining in recent years, outbreaks of Plasmodium vivax malaria were still being reported in rural areas south of the Yellow River. To better understand the transmission dynamics of P. vivax parasites in China, the extent of genetic diversity of P. vivax populations circulating in Bozhou of Anhui province of China were investigated using three polymorphic genetic markers: merozoite surface proteins 1 and 3α (pvmsp-1 and pvmsp-3α) and circumsporozoite protein (pvcsp).MethodsForty-five P. vivax clinical isolates from Bouzhou of Anhui province were collected from 2009 to 2010 and were analysed using PCR/RFLP or DNA sequencing.ResultsSeven and six distinct allelic variants were identified using PCR/RFLP analysis of pvmsp-3α with Hha I and Alu I, respectively. DNA sequence analysis of pvmsp-1 (variable block 5) revealed that there were Sal-I and recombinant types but not Belem type, and seven distinct allelic variants in pvmsp-1 were detected, with recombinant subtype 2 (R2) being predominant (66.7%). All the isolates carried pvcsp with VK210 type but not VK247 or P. vivax-like types in the samples. Sequence analysis of pvcsp gene revealed 12 distinct allelic variants, with VK210-1 being predominant (41.5%).ConclusionsThe present data indicate that there is some degree of genetic diversity among P. vivax populations in Anhui province of China. The genetic data obtained may assist in the surveillance of P. vivax infection in endemic areas or in tracking potential future disease outbreak.

Mast cells modulate acute toxoplasmosis in murine models.

The role of mast cells (MCs) in Toxoplasma gondii infection is poorly known. Kunming outbred mice were infected intraperitoneally with RH strain T. gondii, either treated with compound 48/80 (C48/80, MC activator) or disodium cromoglycate (DSCG, MC inhibitor). Compared with infected controls, infected mice treated with C48/80 exhibited significantly increased inflammation in the liver (P < 0.01), spleen (P < 0.05), and mesentery (P < 0.05) tissues, higher parasite burden in the peritoneal lavage fluids (P < 0.01), and increased levels of mRNA transcripts of T. gondii tachyzoite surface antigen 1 (SAG1) gene in the spleen and liver tissues (P < 0.01), accompanied with significantly increased Th1 cytokine (IFN-γ, IL-12p40, and TNF-α) (P < 0.01) and decreased IL-10 (P < 0.01) mRNA expressions in the liver, and increased IFN-γ (P < 0.01) and IL-12p40 (P < 0.01) but decreased TNF-α (P < 0.01) and IL-4 (P < 0.01) in the spleens of infected mice treated with C48/80 at day 9-10 p.i. Whereas mice treated with DSCG had significantly decreased tissue lesions (P < 0.01), lower parasite burden in the peritoneal lavage fluids (P < 0.01) and decreased SAG1 expressions in the spleen and liver tissues (P < 0.01), accompanied with significantly increased IFN-γ (P < 0.01) and IL-12p40 (P < 0.05) in the liver, and decreased IFN-γ (P < 0.05) and TNF-α (P < 0.01) in the spleens; IL-4 and IL-10 expressions in both the spleen and liver were significantly increased (P < 0.01) in the infected mice treated with DSCG. These findings suggest that mediators associated with the MC activation may play an important role in modulating acute inflammatory pathogenesis and parasite clearance during T. gondii infection in this strain of mice. Thus, MC activation/inhibition mechanisms are potential novel targets for the prevention and control of T. gondii infection.

The influences of siliceous waste on blended cement properties

The influences of siliceous waste on the properties of fly ash and blast furnace slag cement were studied, and its optimum mixing amount in blended cement was determined. The strength, setting time, resistance to chemical attack, dry shrinkage, and impermeability of blended cement mixed with siliceous waste were also investigated by different experiments. The measurement of pore size distribution for hardened cement pastes made by Poremaster-60 was recorded and analyzed in this article.