Progression of chronic pulmonary tuberculosis in mice intravenously infected with ethambutol resistant Mycobacterium tuberculosis

Purpose: Ethambutol (EMB) is an important first line drug, however little information on its molecular mechanism of resistance and pathogenicity of resistant isolates is available. Present work was designed to study virulence of the EMB resistant M. tuberculosis strains and the host responses in-vivo on infection of EMB resistant M. tuberculosis using Balb/c mouse model of infection. Methods: Three groups of Balb/c mice (female, age 4-6 wk; 21 mice in each group) were infected intravenously with 106 CFU of M. tuberculosis H37Rv and two EMB resistant clinical isolates. Age and sex matched control animals were mock inoculated with Middlebrook 7H9 broth alone. At 10, 20, 30, 40, 50, 60, and 70 days post-infection three animals from each group were sacrificed by cervical dislocation and lung tissue was collected for further analysis. Results: Infection with EMB resistant M. tuberculosis led to progressive and chronic disease with significantly high bacillary load (p=0.02). Massive infiltration and exacerbated lung pathology with increased expression of IFN-γand TNF-αwas observed in lungs of mice infected with EMB resistant strains. The present study suggests that infection with EMB resistant M. tuberculosis leads to chronic infection with subsequent loss of lung function, bacterial persistence with elevated expression of TNF-αresulting in increased lung pathology. Conclusion: These findings highlight that EMB resistant M. tuberculosis regulates host immune response differentially and its pathogenicity is different from drug sensitive strains of M. tuberculosis.     

Immune pathology in pulmonary tuberculosis

The data of modem literature and the results of original investigations on mechanisms of immunopathological alterations in tuberculosis infection are presented. The role of cellular and humoral parts of immunity in pathogenesis of pulmonary tuberculosis is discussed and cytokine-mediated mechanisms of disorders in a specific immune response are analysed.     

Phosphodiesterase-4 inhibition combined with isoniazid treatment of rabbits with pulmonary tuberculosis reduces macrophage activation and lung pathology

Tuberculosis (TB) is responsible for significant morbidity and mortality worldwide. Even after successful microbiological cure of TB, many patients are left with residual pulmonary damage that can lead to chronic respiratory impairment and greater risk of additional TB episodes due to reinfection with Mycobacterium tuberculosis. Elevated levels of the proinflammatory cytokine tumor necrosis factor-α and several other markers of inflammation, together with expression of matrix metalloproteinases, have been associated with increased risk of pulmonary fibrosis, tissue damage, and poor treatment outcomes in TB patients. In this study, we used a rabbit model of pulmonary TB to evaluate the impact of adjunctive immune modulation, using a phosphodiesterase-4 inhibitor that dampens the innate immune response, on the outcome of treatment with the antibiotic isoniazid. Our data show that cotreatment of M. tuberculosis infected rabbits with the phosphodiesterase-4 inhibitor CC-3052 plus isoniazid significantly reduced the extent of immune pathogenesis, compared with antibiotic alone, as determined by histologic analysis of infected tissues and the expression of genes involved in inflammation, fibrosis, and wound healing in the lungs. Combined treatment with an antibiotic and CC-3052 not only lessened disease but also improved bacterial clearance from the lungs. These findings support the potential for adjunctive immune modulation to improve the treatment of pulmonary TB and reduce the risk of chronic respiratory impairment.     

Changes in the cellular elements of the thymus gland in experimental destructive pulmonary tuberculosis]

Lymphoid elements of the thymus were studied by scanning electron microscopy in rabbits susceptible to tuberculosis. The complete Freund adjuvant causes in the thymus a 3-fold decrease in the number of cells with the properties of T-lymphocytes, and an appearance of a new type of cell elements (polygonal shape, with cytoplasmic outgrowths). Formation of a focus of tuberculosis and the development of destructive changes in the lungs occur under conditions of a progressive decrease in the number of T- and B-lymphocytes in the thymus. Delimitation of the pathological process in the lung is characterized by an increase in the number of T- and B-lymphocytes and considerable predominance of polygonally shaped cells with cytoplasmic outgrowths of different lengths and their subsequent replacement by a cell form transitory between T- and B-lymphocytes. A relatively favourable course of the process in the lungs is observed when the cell elements in the thymus differentiate towards B-lymphocytes.     

Renal involvement in chronic pulmonary tuberculosis

Fifty indoor patients of chronic pulmonary tuberculosis were studied for renal involvement. There were 36 (72%) males and 14 (28%) females. Age of the patients was ranging from 16 to 70 years. Most of the patients were receiving treatment for tuberculosis for more than 1 year. Frequency of micturition and dysuria were the commonest symptoms observed. Urine smear for mycobacteria was negative in all patients however culture was positive in 6% patients. Renal biopsy was attempted in all patients but was successful in 35 patients. It revealed interstitial nephritis in 28.5%; amyloidosis in 17.1%, glomerulonephritis in 17.1%, tubercular pyelonephritis in 5.6%; pyelonephritis combined with amyloidosis in 8.5% patients. Non-specific changes were observed in 14.3% patients and in 8.5% patients tissue was inadequate for biopsy study.     

CD8- and CD95/95L-dependent mechanisms of resistance in mice with chronic pulmonary tuberculosis

The role of CD8 T lymphocytes in the immune response to Mycobacterium tuberculosis infection remains enigmatic, with persuasive reports of both cytolytic and noncytolytic (cytokine-mediated) responses to infection. To address the importance of the cytolytic mechanisms, mice with targeted disruptions for CD8 and perforin or with gene mutations in the CD95/ CD95L signaling pathway were exposed to pulmonary infection. All mice tested showed no differences in their ability to contain the growth of infection during the early phase of disease. As the chronic phase of the disease ensued, however, both CD8- and CD95/CD95L-deficient mice gradually lost their ability to limit bacterial growth. This was associated with a tendency toward pyogenic inflammation in the lung. This tendency was not seen in the perforin gene-disrupted mice. In CD8 gene-disrupted mice, the ability to generate interferon-gamma secreting T cells was unimpaired. Although these cells were capable of entering the lung they were unable to influence the increasing bacterial load in this organ.     

Immunization with a mycobacterial lipid vaccine improves pulmonary pathology in the guinea pig model of tuberculosis

Lipids and glycolipid molecules derived from Mycobacterium tuberculosis can be presented to T cells by CD1 cell-surface molecules in humans. These lipid-specific T cells are cytolytic, secrete pro-inflammatory cytokines and have bactericidal activity. Here, we describe studies in which lipids from M. tuberculosis were incorporated into liposomes with adjuvant and tested as vaccines in a guinea pig aerosol tuberculosis challenge model. Animals vaccinated with mycobacterial lipids showed reduced bacterial burdens in the lung and spleen at 4 weeks after infection. In addition, the lungs of lipid-vaccinated animals also had significantly less pathology, with granulomatous lesions being smaller and more lymphocytic. In contrast, animals receiving only vehicle control immunizations had granulomatous lesions that were larger and often contained caseous necrotic centers. Quantification of histopathology by morphometric analysis revealed that the overall percentage of lung occupied by diseased tissue was significantly smaller in lipid-vaccinated animals as compared to vehicle control animals. In addition, the mean area of individual granulomatous lesions was found to be significantly smaller in both lipid- and bacillus Calmette-Guerin-vaccinated guinea pigs. These data support an important role for lipid antigens in the immune response to M. tuberculosis infection, potentially through the generation of CD1-restricted T cells. Immunogenic lipids thus represent a novel class of antigens that might be included to enhance the protective effects of subunit vaccine formulations.     

SWR mice are highly susceptible to pulmonary infection with Mycobacterium tuberculosis

Inbred mice differ in their abilities to control the growth of Mycobacterium tuberculosis in the lung and can as a result be regarded as either resistant or susceptible strains. In this study we report that the SWR mouse is both highly susceptible and in addition appears incapable of establishing a characteristic state of chronic disease after low-dose aerosol infection. In comparison to C57BL/6 mice, SWR mice were unable to contain the bacterial load in the lungs, resulting in progressive fatal disease. Histologic analysis of the lung tissue revealed evidence of a florid inflammatory cell response in the SWR mice leading to degeneration and necrosis and consolidation of a large percentage of the lung surface area. Digestion of infected lungs and analysis by flow cytometry demonstrated an initially similar but eventually higher number of lymphocytes accumulating in the SWR mice. Additionally, in contrast to the C57BL/6 mice, SWR mice had a significantly lower percentage of CD4 T cells in the lungs showing evidence of proliferation and positive intracellular staining for gamma interferon during the first two months of infection, and a lower percentage of both CD4 and CD8T cells exhibiting differentiation to an effector/memory phenotype during the first month of infection. We propose that further investigation of the SWR mouse may provide a new animal model for immunocompetent individuals apparently unable to effectively control the growth of M. tuberculosis in the lung.     

IgE-FcεRI交联促进过敏性哮喘小鼠动脉粥样硬化的发生发展

 目的：观察过敏性哮喘加速小鼠动脉粥样硬化（AS）的发生和发展是否与Th2细胞及白细胞介素4（IL-4）有关,以及免疫球蛋白E（IgE）-Fc ε受体I（FcεRI）交联激活巨噬细胞途径在其中发挥的作用。方法：取6周龄的ApoE^-/-小鼠,以卵清蛋白致敏和激发建立过敏性哮喘模型,并分为对照组、哮喘安慰剂组和哮喘IL-4单克隆抗体干预组,分别干预8周,干预结束后处死小鼠,油红O染色检测主动脉根部斑块面积,流式细胞术检测脾脏Th2细胞比例,real-time PCR检测IL-4、IL-6、单核细胞趋化蛋白1（MCP1）和巨噬细胞炎症蛋白1α（MIP1α）的mRNA表达水平,ELISA法检测血清IL-4和IgE的含量。结果：与对照组相比,过敏性哮喘ApoE^-/-小鼠主动脉根部AS病变显著加重,并伴有体内Th2细胞和IL-4水平的增高,同时斑块处IgE和FcεRIα的表达显著增高,MCP-1、MIP-1α和IL-6的mRNA表达也显著增加;IL-4单克隆抗体干预8周后,主动脉根部AS病变缓解的同时,增高的IgE和FcεRIα表达被显著抑制,巨噬细胞相关炎性因子的表达水平也显著降低。结论：过敏性哮喘显著加速ApoE^-/-小鼠AS病变进展,此作用与体内Th2细胞和IL-4水平增加,以及IgE-FcεRI交联激活巨噬细胞途径有关。     

StIL-17 gene polymorphisms in the development of pulmonary tuberculosis

We conduct a case-control study to explore the possible association between IL-17 gene polymorphisms and development of TB. Methods: The study population comprised 428 TB subjects and 428 control subjects between January 2013 and June 2014. Genotyping analyses of IL-17A rs2275913 and rs3748067 and IL-17F rs763780 and rs9382084 were analyzed using polymerase chain reaction-restriction fragment length of polymorphism (PCR-RFLP). Results: The TB cases were more likely to have a habit of smoking when comparing with controls. By conditional logistic regression analysis, individuals carrying CC genotype of rs763780 were more likely to have a significantly increased risk of TB when compared with TT genotype. The OR (95% CI) for CC genotype of rs763780 was 2.98 (1.58-5.92). Conclusion: In conclusion, we suggest that rs763780 play a critical role in the etiology of TB. These findings could be helpful in identifying individuals at increased risk for developing TB.