Release of reactive oxygen and nitrogen intermediates from monocytes of patients with pulmonary tuberculosis

Lysosomal enzymes and the oxygen burst capability of monocyte-derived macrophages in active drug-resistant tuberculosis patients in relation to cell attachment

Drug resistance to tuberculosis (TB) has become an obstacle in eliminating tuberculosis. The transmission of drug-resistant TB from patients increases the incidence of primary drug-resistant (DR) TB in individuals who are in close contact. Therefore, it is necessary to incorporate an immunological approach into preventive therapy. This study focuses on the activity of lysosomal enzymes, oxygen bursts, and the attachment ability of macrophages among individuals diagnosed with active drug-resistant TB compared with close contacts with latent TB or healthy cases. We measured macrophage oxygen burst ability (Water-soluble tetrazolium salt (WST) test, Nitric Oxide production, and myeloperoxidase activity) and the degradative ability of lysosomes (activity of the β-glucuronidase and acid phosphatase enzymes). Six active DR-TB patients and 18 close-contact cases (8 Latent Tuberculosis Infection (LTBI); 10 healthy) were recruited at Universitas Indonesia Hospital. The macrophage attachment of the LTBI group was higher than in the other groups. NO production, myeloperoxidase activity, β-glucuronidase, and acid phosphatase were higher in the active DR-TB group. A negative correlation was uncovered between phagocytosis and NO production, myeloperoxidase activity, and lysosomal enzymes. The difference in macrophage function is expected to be a further reference in active DR-TB treatment or preventive therapy.

Experimental Evolution Reveals Redox State Modulates Mycobacterial Pathogenicity

Understanding how Mycobacterium tuberculosis has evolved into a professional pathogen is helpful in studying its pathogenesis and for designing vaccines. We investigated how the evolutionary adaptation of M. smegmatis mc²51 to an important clinical stressor H₂O₂ allows bacteria to undergo coordinated genetic mutations, resulting in increased pathogenicity. Whole-genome sequencing identified a mutation site in the fur gene, which caused increased expression of katG. Using a Wayne dormancy model, mc²51 showed a growth advantage over its parental strain mc²155 in recovering from dormancy under anaerobic conditions. Meanwhile, the high level of KatG in mc²51 was accompanied by a low level of ATP, which meant that mc²51 is at a low respiratory level. Additionally, the redox-related protein Rv1996 showed different phenotypes in different specific redox states in M. smegmatis mc²155 and mc²51, M. bovis BCG, and M. tuberculosis mc²7000. In conclusion, our study shows that the same gene presents different phenotypes under different physiological conditions. This may partly explain why M. smegmatis and M. tuberculosis have similar virulence factors and signaling transduction systems such as two-component systems and sigma factors, but due to the different redox states in the corresponding bacteria, M. smegmatis is a nonpathogen, while M. tuberculosis is a pathogen. As mc²51 overcomes its shortcomings of rapid removal, it can potentially be developed as a vaccine vector.

The mechanism of redox sensing in Mycobacterium tuberculosis

Tuberculosis epidemics have defied constraint despite the availability of effective treatment for the past half-century. Mycobacterium tuberculosis, the causative agent of TB, is continually exposed to a number of redox stressors during its pathogenic cycle. The mechanisms used by Mtb to sense redox stress and to maintain redox homeostasis are central to the success of Mtb as a pathogen. Careful analysis of the Mtb genome has revealed that Mtb lacks classical redox sensors such as FNR, FixL, and OxyR. Recent studies, however, have established that Mtb is equipped with various sophisticated redox sensors that can detect diverse types of redox stress, including hypoxia, nitric oxide, carbon monoxide, and the intracellular redox environment. Some of these sensors, such as heme-based DosS and DosT, are unique to mycobacteria, whereas others, such as the WhiB proteins and anti-σ factor RsrA, are unique to actinobacteria. This article provides a comprehensive review of the literature on these redox-sensory modules in the context of TB pathogenesis.

Is rheumatoid arthritis a consequence of natural selection for enhanced tuberculosis resistance?

Although the bubonic plague or "Black Death" is notorious for the toll it took on the population of Europe in the middle ages, another epidemic, the "White Death" of tuberculosis is responsible for millions of deaths worldwide over the past 300 years. With one in four deaths due to tuberculosis in Western Europe and the United States in the 19th century, this disease undoubtedly acted as a powerful genetic selective force. The epidemiology of modern day rheumatoid arthritis (RA) is strikingly similar to the epidemiology of tuberculosis 100-200 years ago, suggesting the possibility that genetic factors that enhanced survival in tuberculosis epidemics are now influencing susceptibility to RA. Recent advances in the analysis of genetic polymorphisms associated with disease have identified several genes linked to RA susceptibility that encode proteins involved in the immune response to Mycobacterium tuberculosis infection, including TNF-alpha, NRAMP1, PARP-1, HLA-DRB1, and PADI4. These results suggest that rheumatoid arthritis, and possibly other autoimmune diseases, are modern day manifestations of the genetic selective pressure exerted by tuberculosis epidemics of the recent past.

Nitric oxide production by carpet shell clam (Ruditapes decussatus) hemocytes

We have demonstrated that carpet shell clam (Ruditapes decussatus) hemocytes produce nitric oxide (NO) in response to zymosan or bacterial lipopolysaccharide (LPS). This NO production was partially inhibited by the NO synthase inhibitor, N-omega-nitro-L-arginine (L-NAME). The capability of clam hemocytes to produce NO in response to the bacterial pathogen Vibrio tapetis was also studied. Incubation with bacteria induced a significant NO production by clam hemocytes, even though exogenous NO only slightly decreased the growth of V. tapetis. The effect of exogenous NO on the capability of clam hemocytes to phagocytose labeled Escherichia coli was studied using two different NO donors S-nitroso-N-acetyl-penicillamine (SNAP), and diethylenetriamine NO adduct (DETA/NO). Exogenous NO did not increase hemocyte phagocytosis, indicating that NO does not mediate phagocytosis in this species. These results are in accordance to those observed in other mollusk species, in which NO was independent of phagocytosis and constitutes an alternative method of killing invading pathogens.

Localized increase in nitric oxide production and the expression of nitric oxide synthase isoforms in rat uterus with experimental intrauterine infection

OBJECTIVE

We recently reported that nitric oxide was associated with increased mortality among pregnant rats with intrauterine infection. In our current study we investigated the expression of different isoforms of nitric oxide synthases and nitric oxide in the nonpregnant rat uterus with experimental intrauterine infection.

STUDY DESIGN

Pathogenic Escherichia coli was inoculated into the uterine lumen of ovariectomized rats. Animals were killed after inoculation, and uterine horns were collected for assessing nitric oxide production with high-performance liquid chromatography and nitric oxide synthase (type II and type III) protein expression with Western immunoblotting and immunofluorescence methods.

RESULTS

(1) Nitric oxide production increased in the infected uterine horn in a time-dependent manner after intrauterine infection but did not increase in the uninfected horn. (2) Nitric oxide synthase type III protein contents did not show a difference between infected and uninfected horns, and type III nitric oxide synthase was expressed by the epithelial cells and smooth muscle cells. (3) Type II nitric oxide synthase was abundantly expressed in infected horns but was not expressed in uninfected horns. Immunofluorescence data indicated that macrophages and natural killer cells, located in the endometrial layer clustering around epithelial cells, expressed type II protein.

CONCLUSION

We suggest that localized increase in type II nitric oxide synthase expression and nitric oxide production occurs in response to intrauterine infection and that the nitric oxide system may play a role in host response to restrict the infection.

Increased serum concentrations of conjugated diens and malondialdehyde in patients with pulmonary tuberculosis

During pulmonary inflammation increased amounts of reactive oxygen species (ROS) and reactive nitrogen intermediates (RNI) are produced as a consequence of phagocyte respiratory burst. One of the manifestation of these free radical-mediated processes is lipid peroxidation (LP). The aim of our study was to assess the concentration of lipid peroxidation products (LPPs), conjugated diens (CD) and malondialdehyde (MDA), in patients with active TB. Forty-two patients were enrolled into the study. Half (group I) had advanced TB and were sputum smear-positive. The remainder (group II) had only small radiographical changes and were sputum smear-negative. Serum concentrations of CD and MDA were measured at days 0, 7, 14 and 28 in group I and day 0 in group II. We found that in all patients with active TB CCD (1.0 +/- 0.05A233) and CMDA (2.01 +/- 0.16 nmol dl-1) were significantly elevated compared to healthy controls (0.67 +/- 0.03A233 and 1.36 +/- 0.08 nmol dl-1, respectively) (P < 0.001). The highest levels of LPPs were in patients with advanced TB. These concentrations were stable during the first month of anti-tuberculous therapy. Our data indicated that, as in bacterial pneumonia, LPPs were enhanced in active TB. The levels of LPPs depended on the form of the disease as they were higher in subjects with advanced disease than in those with only small radiographical changes. Further studies are needed to assess the role of antioxidants as adjuvant therapy in patients with pulmonary TB.

Nitric oxide production and nitric oxide synthase type 2 expression by human mononuclear phagocytes: a review

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Reactive oxygen intermediates and reactive nitrogen intermediates in copper intrauterine device users

The mechanism of action of copper in copper intrauterine devices (Cu IUD) as an antimicrobial agent is not well understood. Copper and iron are supposed to be responsible for release of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI), which are very active in the presence of infection. The copper in a copper IUD could be responsible for limiting pelvic inflammatory disease. The present study was composed of 20 IUD seekers in whom ROI and RNI were studied before insertion of Cu IUD and then at 1, 4, and 12 weeks afterward. ROI showed a rise after insertion, whereas RNI showed a steady decline. Hence, it is presumed that the rise in ROI could be responsible for both the bactericidal effect of Cu IUD and also for the fall in RNI.