Critical role of macrophages and their activation via MyD88-NFκB signaling in lung innate immunity to Mycoplasma pneumoniae

Mycoplasma pneumoniae (Mp), a common cause of pneumonia, is associated with asthma; however, the mechanisms underlying this association remain unclear. We investigated the cellular immune response to Mp in mice. Intranasal inoculation with Mp elicited infiltration of the lungs with neutrophils, monocytes and macrophages. Systemic depletion of macrophages, but not neutrophils, resulted in impaired clearance of Mp from the lungs. Accumulation and activation of macrophages were decreased in the lungs of MyD88(-/-) mice and clearance of Mp was impaired, indicating that MyD88 is a key signaling protein in the anti-Mp response. MyD88-dependent signaling was also required for the Mp-induced activation of NFκB, which was essential for macrophages to eliminate the microbe in vitro. Thus, MyD88-NFκB signaling in macrophages is essential for clearance of Mp from the lungs.     

A systemic lupus erythematosus-associated R77H substitution in the CD11b chain of the Mac-1 integrin compromises leukocyte adhesion and phagocytosis

The Mac-1 integrin is expressed mainly on myeloid cells and binds several ligands, including members of the ICAM family and the complement factor iC3b. It is involved in essential immunological processes, such as leukocyte extravasation and phagocytosis. In addition, Mac-1 has been described to negatively regulate immune cell signaling. Recently, a single nucleotide polymorphism conferring an amino acid change in the Mac-1 integrin extracellular domain, R77H, was shown to be associated with systemic lupus erythematosus. Here, we demonstrate that the R77H-substituted Mac-1 can be expressed on the cell surface in transfected cells and can undergo conformational changes in response to integrin activation. The affinity of the integrin for ICAMs is only partially reduced, but cell adhesion to ICAM-1 and ICAM-2 is severely compromised, and Jβ2.7 cells expressing R77H substituted integrins are deficient in adhesion to ICAM-1 under shear flow conditions. Importantly, cell adhesion to the complement factor iC3b is also diminished, and COS cells expressing R77H-substituted integrins display reduced iC3b-dependent phagocytosis. In addition, U937 cells expressing R77H-CD11b display increased IL-6 production as compared with WT-CD11b-expressing cells. These results suggest that the R77H substitution results in the deficiency of the mutated integrin to mediate cell adhesion to ligands such as ICAMs and iC3b. These deficiencies may ultimately lead to detrimental effects on the immune system and contribute to the development of systemic lupus erythematosus.     

Substituted aminopyridines as potent and selective phosphodiesterase-4 inhibitors

The synthesis and the biological evaluation of new potent phosphodiesterase type 4 (PDE4) inhibitors are presented. This new series was elaborated by replacement of the metabolically resistant phenyl hexafluorocarbinol of L-791,943 (1) by a substituted aminopyridine residue. The structure-activity relationship of N-substitution on 3 led to the identification of (-)-3n which exhibited a good PDE4 inhibitor activity (HWB-TNFalpha=0.12 microM) and an improved pharmacokinetic profile over L-791,943 (rat t(1/2)=2 h). (-)-3n was well tolerated in ferret with an emetic threshold of 30 mg/kg (po) and was found to be active in the ovalbumin-induced bronchoconstriction model in guinea pig (54%, 0.1 mg/kg, ip) as well as the ascaris-induced bronchoconstriction model in sheep (64%/97%, early/late, 0.5 mg/kg, iv).     

Protective effect of bixin on carbon tetrachloride-induced hepatotoxicity in rats

Background

The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl₄) in rats.

Results

The animals were divided into four groups with six rats in each group. CCl₄ (0.125 mL kg^-1 body wt.) was injected intraperitoneally, and bixin (5.0 mg kg^-1 body wt.) was given by gavage 7 days before the CCl₄ injection. Bixin prevented the liver damage caused by CCl₄, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl₄ by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment.

Conclusion

Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl₄ is related to the antioxidant activity of the compound.     

Technical Performance Evaluation of the MyT4 Point of Care Technology for CD4+ T Cell Enumeration

Objective

Though absolute CD4+ T cell enumeration is the primary gateway to antiretroviral therapy initiation for HIV-positive patients in all developing countries, patient access to this critical diagnostic test is relatively poor. We technically evaluated the performance of a newly developed point-of-care CD4+ T cell technology, the MyT4, compared with conventional CD4+ T cell testing technologies.

Design

Over 250 HIV-positive patients were consecutively enrolled and their blood tested on the MyT4, BD FACSCalibur, and BD FACSCount.

Results

Compared with the BD FACSCount, the MyT4 had an r² of 0.7269 and a mean bias of −23.37 cells/µl. Compared with the BD FACSCalibur, the MyT4 had an r² of 0.5825 and a mean bias of −46.58 cells/µl. Kenya currently uses a CD4+ T cell test threshold of 350 cells/µl to determine patient eligibility for antiretroviral therapy. At this threshold, the MyT4 had a sensitivity of 95.3% (95% CI: 88.4–98.7%) and a specificity of 87.9% (95% CI: 82.3–92.3%) compared with the BD FACSCount and sensitivity and specificity of 88.2% (95% CI: 79.4–94.2%) and 84.2% (95% CI: 78.2–89.2%), respectively, compared with the BD FACSCalibur. Finally, the MyT4 had a coefficient of variation of 12.80% compared with 14.03% for the BD FACSCalibur.

Conclusions

We conclude that the MyT4 performed well at the current 350 cells/µl ART initiation eligibility threshold when used by lower cadres of health care facility staff in rural clinics compared to conventional CD4+ T cell technologies.     

Harmonizing Labeling and Analytical Strategies to Obtain Protein Turnover Rates in Intact Adult Animals

Changes in the abundance of individual proteins in the proteome can be elicited by modulation of protein synthesis (the rate of input of newly synthesized proteins into the protein pool) or degradation (the rate of removal of protein molecules from the pool). A full understanding of proteome changes therefore requires a definition of the roles of these two processes in proteostasis, collectively known as protein turnover. Because protein turnover occurs even in the absence of overt changes in pool abundance, turnover measurements necessitate monitoring the flux of stable isotope–labeled precursors through the protein pool such as labeled amino acids or metabolic precursors such as ammonium chloride or heavy water. In cells in culture, the ability to manipulate precursor pools by rapid medium changes is simple, but for more complex systems such as intact animals, the approach becomes more convoluted. Individual methods bring specific complications, and the suitability of different methods has not been comprehensively explored. In this study, we compare the turnover rates of proteins across four mouse tissues, obtained from the same inbred mouse strain maintained under identical husbandry conditions, measured using either [¹³C₆]lysine or [²H₂]O as the labeling precursor. We show that for long-lived proteins, the two approaches yield essentially identical measures of the first-order rate constant for degradation. For short-lived proteins, there is a need to compensate for the slower equilibration of lysine through the precursor pools. We evaluate different approaches to provide that compensation. We conclude that both labels are suitable, but careful determination of precursor enrichment kinetics in amino acid labeling is critical and has a considerable influence on the numerical values of the derived protein turnover rates.     

The economics of schistosomiasis chemotherapy

The optimal choice o f chemotherapy regime arises in the design o f every schistosomiasis control programme. This choice is o f particular contemporary interest for two reasons. At one extreme the development of effective single-dose oral drugs such as praziquantel and oxamniquine makes mass chemotherapy a practical option. At the other extreme there has been a revival o f advocacy for some form o f selective treatment. But all developing countries that contemplate schistosomiasis control face severe budget constraints, requiring careful analysis o f the economics o f chemotherapy. In this article, Nick Prescott presents a generalized framework For resource allocation in schistosomiasis chemotherapy, demonstrating that the optimal choice o f chemotherapy regime depends critically on the level of budget constraint, the unit costs o f screening and treatment, and rates o f compliance with screening and chemotherapy-all factors which are usually neglected in the choice o f control strategy.     

hnRNP C and polypyrimidine tract-binding protein specifically interact with the pyrimidine-rich region within the 3'NTR of the HCV RNA genome

Like other members of the Flaviviridae family, the 3' non-translated region (NTR) of the hepatitis C virus (HCV) is believed to function in the initiation and regulation of viral RNA replication by interacting with components of the viral replicase complex. To inves-tigate the possibility that host components may also participate in this process, we used UV cross-linking assays to determine if any cellular proteins could bind specifically to the 3'NTR RNA. We demonstrate the specific interaction of two host proteins with the extensive pyrimidine-rich region within the HCV 3'NTR. One host protein migrates as a doublet with a molecular weight of 57 kDa and is immunoreactive with antisera specific for polypyrimidine tract-binding protein (PTB), and the other protein (35 kDa) is recognized by a monoclonal antibody specific for heterogeneous nuclear ribonucleoprotein C (hnRNP C). These results suggest that recognition of the large pyrimidine-rich region by PTB and hnRNP C may play a role in the initiation and/or regulation of HCV RNA replication.