Acidic mammalian chitinase tuning after enteric helminths eradication in inflammatory respiratory disease patients.

AIM: This study aimed at investigating the presence of intestinal parasitic infections in inflammatory respiratory diseases patients during the disease attack, and measuring the acidic mammalian chitinase (AMCase) gene expression in blood before and after infection eradication. METHODOLOGY: This case-control study included 123 inflammatory respiratory diseases patients and 120 apparently healthy individuals. Repeated stool examination was done, while total and specific IgE were measured. AMCase gene expression was analysed by real time-polymerase chain reaction (RT-PCR). RESULTS: Infection was detected in 32.5% of the diseased and 23.25% of the healthy individuals. Higher rate of the helminthic infection was detected (23.57) in comparison to the protozoal (12.19%) in the patients. A significantly higher rate of infection with the chitin-rich helminths "Enterobius vermicularis & Hymenolepis nana" and level of anti-Dermatophagoide-IgE were reported in the patients (14.63%, 6.5% and 23.57%, respectively). AMCase expression was significantly higher in helminths-infected patients than the noninfected, or protozoa infected. After infection eradication, AMCase expression significantly declined in the previously helminth-infected patients (mean ± SD = 13.9 ± 3.918 before and 4.515 ± 1.93 after), but insignificantly affected in the protozoa infected (mean ± SD = 2.095 ± .285 before and 2.675 ± 1.181 after). CONCLUSION: Chitin-rich intestinal helminths are suspected to precipitate Th2-immune response in remote tissues by enhancing systemic AMCase expression through intestinal mucosa and macrophages irritation.

Caspase-11 Plays a Protective Role in Pulmonary Acinetobacter baumannii Infection.

Activation of caspase-11 by some Gram-negative bacteria triggers the caspase-1/interleukin 1ß (IL-1ß) pathway, independent of canonical inflammasomes. Acinetobacter baumannii is a Gram-negative, conditionally pathogenic bacterium that can cause severe pulmonary infection in hospitalized patients. A. baumannii was revealed to activate canonical and noncanonical inflammasome pathways in bone marrow-derived macrophages (BMDMs). Pulmonary infection of caspase-11-/- mice with A. baumannii showed that caspase-11 deficiency impaired A. baumannii clearance, exacerbated pulmonary pathological changes, and enhanced susceptibility to A. baumannii These data indicate that the caspase-11-mediated innate immune response plays a crucial role in defending against A. baumannii.

Attenuated heme oxygenase-1 responses predispose the elderly to pulmonary nontuberculous mycobacterial infections.

Pulmonary infections with nontuberculous mycobacteria (P-NTM), such as by Mycobacterium avium complex (M. avium), are increasingly found in the elderly, but the underlying mechanisms are unclear. Recent studies suggest that adaptive immunity is necessary, but not sufficient, for host defense against mycobacteria. Heme oxygenase-1 (HO-1) has been recognized as a critical modulator of granuloma formation and programmed cell death in mycobacterial infections. Old mice (18-21 mo) infected with M. avium had attenuated HO-1 response with diffuse inflammation, high burden of mycobacteria, poor granuloma formation, and decreased survival (45%), while young mice (4-6 mo) showed tight, well-defined granuloma, increased HO-1 expression, and increased survival (95%). To further test the role of HO-1 in increased susceptibility to P-NTM infections in the elderly, we used old and young HO-1+/+ and HO-1-/- mice. The transcriptional modulation of the JAK/STAT signaling pathway in HO-1-/- mice due to M. avium infection demonstrated similarities to infected wild-type old mice with upregulation of SOCS3 and inhibition of Bcl2. Higher expression of SOCS3 with downregulation of Bcl2 resulted in higher macrophage death via cellular necrosis. Finally, peripheral blood monocytes (PBMCs) from elderly patients with P-NTM also demonstrated attenuated HO-1 responses after M. avium stimulation and increased cell death due to cellular necrosis (9.69% ± 2.02) compared with apoptosis (4.75% ± 0.98). The augmented risk for P-NTM in the elderly is due, in part, to attenuated HO-1 responses, subsequent upregulation of SOCS3, and inhibition of Bcl2, leading to programmed cell death of macrophages, and sustained infection.

Neutrophil elastase causes tissue damage that decreases host tolerance to lung infection with burkholderia species.

Two distinct defense strategies can protect the host from infection: resistance is the ability to destroy the infectious agent, and tolerance is the ability to withstand infection by minimizing the negative impact it has on the host's health without directly affecting pathogen burden. Burkholderia pseudomallei is a Gram-negative bacterium that infects macrophages and causes melioidosis. We have recently shown that inflammasome-triggered pyroptosis and IL-18 are equally important for resistance to B. pseudomallei, whereas IL-1ß is deleterious. Here we show that the detrimental role of IL-1ß during infection with B. pseudomallei (and closely related B. thailandensis) is due to excessive recruitment of neutrophils to the lung and consequent tissue damage. Mice deficient in the potentially damaging enzyme neutrophil elastase were less susceptible than the wild type C57BL/6J mice to infection, although the bacterial burdens in organs and the extent of inflammation were comparable between C57BL/6J and elastase-deficient mice. In contrast, lung tissue damage and vascular leakage were drastically reduced in elastase-deficient mice compared to controls. Bradykinin levels were higher in C57BL/6 than in elastase-deficient mice; administration of a bradykinin antagonist protected mice from infection, suggesting that increased vascular permeability mediated by bradykinin is one of the mechanisms through which elastase decreases host tolerance to melioidosis. Collectively, these results demonstrate that absence of neutrophil elastase increases host tolerance, rather than resistance, to infection by minimizing host tissue damage.

Acute exacerbations of COPD are associated with significant activation of matrix metalloproteinase 9 irrespectively of airway obstruction, emphysema and infection.

BACKGROUND: Acute exacerbations of chronic obstructive pulmonary disease (AE-COPD) are associated with accelerated aggravation of clinical symptoms and deterioration of pulmonary function. The mechanisms by which exacerbations may contribute to airway remodeling and declined lung function are poorly understood. In this study, we investigated if AE-COPD are associated with differential expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in bronchoalveolar lavage (BAL). METHODS: COPD patients undergoing diagnostic bronchoscopy, with either stable disease (n = 53) or AE-COPD (n = 44), matched for their demographics and lung function parameters were included in this study. Protein levels of MMP-2,-9,-12 and of TIMP-1 and -2 in BAL were measured by ELISA. Enzymatic activity of MMP-2 and -9 was assessed by gelatin zymography. RESULTS: We observed that MMP-9, TIMP-1 and TIMP-2 were significantly increased in BAL during AE-COPD. Furthermore, there was a significant negative correlation of MMP-9, TIMP-1 and TIMP-2 with FEV1% predicted and a significant positive correlation of TIMP-1 and TIMP-2 with RV% predicted in AE-COPD. None of MMPs and TIMPs correlated with DLCO% predicted, indicating that they are associated with airway remodeling leading to obstruction rather than emphysema. In AE-COPD the gelatinolytic activity of MMP-2 was increased and furthermore, MMP-9 activation was significantly up-regulated irrespective of lung function, bacterial or viral infections and smoking. CONCLUSIONS: The results of this study indicate that during AE-COPD increased expression of TIMP-1, TIMP-2, and MMP-9 and activation of MMP-9 may be persistent aggravating factors associated with airway remodeling and obstruction, suggesting a pathway connecting frequent exacerbations to lung function decline.

Effects of an anti-inflammatory VAP-1/SSAO inhibitor, PXS-4728A, on pulmonary neutrophil migration.

BACKGROUND AND PURPOSE: The persistent influx of neutrophils into the lung and subsequent tissue damage are characteristics of COPD, cystic fibrosis and acute lung inflammation. VAP-1/SSAO is an endothelial bound adhesion molecule with amine oxidase activity that is reported to be involved in neutrophil egress from the microvasculature during inflammation. This study explored the role of VAP-1/SSAO in neutrophilic lung mediated diseases and examined the therapeutic potential of the selective inhibitor PXS-4728A. METHODS: Mice treated with PXS-4728A underwent intra-vital microscopy visualization of the cremaster muscle upon CXCL1/KC stimulation. LPS inflammation, Klebsiella pneumoniae infection, cecal ligation and puncture as well as rhinovirus exacerbated asthma models were also assessed using PXS-4728A. RESULTS: Selective VAP-1/SSAO inhibition by PXS-4728A diminished leukocyte rolling and adherence induced by CXCL1/KC. Inhibition of VAP-1/SSAO also dampened the migration of neutrophils to the lungs in response to LPS, Klebsiella pneumoniae lung infection and CLP induced sepsis; whilst still allowing for normal neutrophil defense function, resulting in increased survival. The functional effects of this inhibition were demonstrated in the RV exacerbated asthma model, with a reduction in cellular infiltrate correlating with a reduction in airways hyperractivity. CONCLUSIONS AND IMPLICATIONS: This study demonstrates that the endothelial cell ligand VAP-1/SSAO contributes to the migration of neutrophils during acute lung inflammation, pulmonary infection and airway hyperractivity. These results highlight the potential of inhibiting of VAP-1/SSAO enzymatic function, by PXS-4728A, as a novel therapeutic approach in lung diseases that are characterized by neutrophilic pattern of inflammation.

Increased ß-glucuronidase activity in bronchoalveolar lavage fluid of children with bacterial lung infection: A case-control study.

BACKGROUND AND OBJECTIVE: ß-Glucuronidase is a lysosomal enzyme released into the extracellular fluid during inflammation. Increased ß-glucuronidase activity in the cerebrospinal and peritoneal fluid has been shown to be a useful marker of bacterial inflammation. We explored the role of ß-glucuronidase in the detection of bacterial infection in bronchoalveolar lavage fluid (BALF) of paediatric patients. METHODS: In this case-control study, % polymorphonuclear cell count (PMN%), ß-glucuronidase activity, interleukin-8 (IL-8), tumour necrosis factor-α (TNF-α) and elastase were measured in culture-positive (≥10(4) cfu/mL, C+) and -negative (C-) BALF samples obtained from children. RESULTS: A total of 92 BALF samples were analysed. The median ß-glucuronidase activity (measured in nanomoles of 4-methylumbelliferone (4-MU)/mL BALF/h) was 246.4 in C+ (interquartile range: 71.2-751) and 21.9 in C- (4.0-40.8) (P < 0.001). The levels of TNF-α and IL-8 were increased in C+ as compared with C- (5.4 (1.7-12.6) vs 0.7 (0.2-6.2) pg/mL, P < 0.001 and 288 (76-4300) vs 287 (89-1566) pg/mL, P = 0.042, respectively). Elastase level and PMN% did not differ significantly (50 (21-149) vs 26 (15-59) ng/mL, P = 0.051 and 20 (9-40) vs 18 (9-34) %, P = 0.674, respectively). The area under the curve of ß-glucuronidase activity (0.856, 95% confidence interval (CI): 0.767-0.920) was higher than that of TNF-α (0.718; 95% CI: 0.614-0.806; P = 0.040), IL-8 (0.623; 95% CI: 0.516-0.722; P = 0.001), elastase (0.645; 95% CI: 0.514-0.761; P = 0.008) and PMN% (0.526; 95 % CI: 0.418-0.632; P < 0.001). CONCLUSIONS: This study demonstrates a significant increase of ß-glucuronidase activity in BALF of children with culture-positive bacterial inflammation. In our population ß-glucuronidase activity showed superior predictive ability for bacterial lung infection than other markers of inflammation.

[Efficiency of antibiotics in children with acute respiratory infection complicated by pneumonia dependent on the acetylation type in the Far North regions].

Clinical characteristics of some diseases are defined by the phenotype of metabolic reactions, for example N-acetylation. Genetic polymorphism due to the activity of N-acetyltransferase (N-AT) is common in the majority of human populations. Consequently, persons with "slow" or "fast" acetylation phenotype should be identified. N-AT catalyzes acetylation of a number of medical products. Efficiency of pharmacotherapy is mostly associated with the specific features of medical products biotransformation. The processes of biotransformation with participation of acetyltransferase, monooxygenase or other ferment systems are under the gene control. The aim of the study was to characterize the features of the clinical course of acute respiratory infection complicated by pneumonia as dependent on the acetylation phenotype to predict the character of the disease and optimize the used antibiotic therapy among the native population (Yakut) and the arrived (Russian) in the Far North Regions (Sakha, Yakutia). 112 children with acute respiratory infections complicated by pneumonia and 49 practically healthy ones were examined. For the children with low N-AT activity (less than 30%) it was recommended to be treated with gentamicin which directly takes part in the acetylation and provides the antibiotic therapy efficiency in 80% of the cases. The use of cephalosporin antibiotics (beta-lactams), the metabolism of which is not directly connected with acetylation reactions provided the efficiency in 20% of the cases.

Muramyl dipeptide mediated activation of human bronchial epithelial cells interacting with basophils: a novel mechanism of airway inflammation.

Respiratory tract bacterial infection can amplify and sustain airway inflammation. Intracytosolic nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is one member of the nucleotide binding and oligomerization domain (NOD)-like receptor (NLR) family, which senses the conserved structural peptidoglycan component muramyl dipeptide (MDP) in almost all bacteria. In the present study, activation of the NOD2 ligand MDP on primary human bronchial epithelial cells (HBE) co-cultured with human basophils was investigated. Cytokines, NOD2, adhesion molecules and intracellular signalling molecules were assayed by enzyme-linked immunosorbent assay or flow cytometry. The protein expression of NOD2 was confirmed in basophils/KU812 cells and HBE/human bronchial epithelial cell line (BEAS-2B) cells. MDP was found to up-regulate significantly the cell surface expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 on basophils and HBE in the co-culture system with or without basophil priming by interleukin (IL)-33 (all P < 0·05). MDP could further enhance the release of inflammatory cytokine IL-6 and chemokine CXCL8, and epithelium-derived anti-microbial peptide ß-defensin 2 in the co-culture. HBE cells were the major source for the release of IL-6, CXCL8 and ß-defensin2 upon stimulation by MDP in the co-culture system. The expression of ICAM-1 and VCAM-1 and release of IL-6 and CXCL8 were suppressed by various signalling molecule inhibitors, implying that the interaction between basophils and primary human bronchial epithelial cells could be regulated differentially by the mitogen-activated protein kinase pathways and nuclear transcription factors. The results therefore provide a new insight into the functional role of basophils in innate immunity, and the link between respiratory bacteria-mediated innate immunity and subsequent amplification of allergic inflammation in the airway.

Role of matrix metalloproteinases and their inhibitor in the development of early pulmonary fibrosis in mice infected with influenza A/H5N1 A/goose/Krasnoozerskoye/627/05 virus.

High levels of macrophages and fibroblasts expressing MMP-2, MMP-9, and MMP-10 against the background of progressing early fibrosis of the lungs (manifesting in an increase in volume density of type I, III, IV, and VI collagens) were found in C57Bl/6 mice infected with influenza A/H5N1 A/goose/Krasnoozerskoye/627/05 virus. Progressing fibrosis of the lungs in infected mice was associated with imbalance of collagen synthesis and degradation processes conjugated with high levels of macrophages and fibroblasts expressing TIMP-2.

CFTR negatively regulates cyclooxygenase-2-PGE(2) positive feedback loop in inflammation.

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent anion channel mostly expressed in epithelia. Accumulating evidence suggests that CF airway epithelia are overwhelmed by excessive inflammatory cytokines and prostaglandins (PGs), which eventually lead to the over-inflammatory condition observed in CF lung disease. However, the exact underlying mechanism remains elusive. In this study, we observed increased cyclooxygenase-2 (COX-2) expression and over-production of prostaglandin E(2) (PGE(2)) in human CF bronchial epithelia cell line (CFBE41o--) with elevated NF-κB activity compared to a wild-type airway epithelial cell line (16HBE14o--). Moreover, we demonstrated that CFTR knockout mice had inherently higher levels of COX-2 and NF-κB activity, supporting the notion that lack of CFTR results in hyper-inflammatory signaling. In addition, we identified a positive feedback loop for production of PGE(2) involving PKA and transcription factor, CREB. More importantly, overexpression of wild-type CFTR significantly suppressed COX-2 expression in CFBE41o- cells, and wild-type CFTR protein expression was significantly increased when 16HBE14o-- cells were challenged with LPS as well as PGE(2), indicating possible involvement of CFTR in negative regulation of COX-2/PGE(2). In conclusion, CFTR is a negative regulator of PGE(2)-mediated inflammatory response, defect of which may result in excessive activation of NF-κB, leading to over production of PGE(2) as seen in inflammatory CF tissues.

Use of MMP-8 and MMP-9 to assess disease severity in children with viral lower respiratory tract infections.

Matrix metalloproteinases (MMPs) play an important role in respiratory inflammatory diseases, such as asthma and chronic obstructive pulmonary disease. It was hypothesized that MMP-8 and MMP-9 may function as biological markers to assess disease severity in viral lower respiratory tract infections in children. MMP-8 and MMP-9 mRNA expression levels in peripheral blood mononuclear cells (PBMCs) and granulocytes obtained in both the acute and recovery phase from 153 children with mild, moderate, and severe viral lower respiratory tract infections were determined using real-time PCR. In addition, MMP-8 and MMP-9 concentrations in blood and nasopharyngeal specimens were determined during acute mild, moderate, and severe infection, and after recovery using ELISA. Furthermore, PBMCs and neutrophils obtained from healthy volunteers were stimulated with RSV, LPS (TLR4 agonist), and Pam3Cys (TLR2 agonist) in vitro. Disease severity of viral lower respiratory tract infections in children is associated with increased expression levels of the MMP-8 and MMP-9 genes in both PBMCs and granulocytes. On the contrary, in vitro experiments showed that MMP-8 and MMP-9 mRNA and protein expression in PBMCs and granulocytes is not induced by stimulation with RSV, the most frequent detected virus in young children with viral lower respiratory tract infections. These data indicate that expression levels of the MMP-8 and MMP-9 genes in both PBMCs and neutrophils are associated with viral lower respiratory tract infections disease severity. These observations justify future validation in independent prospective study cohorts of the usefulness of MMP-8 and MMP-9 as potential markers for disease severity in viral respiratory infections.

Inflammasome activation by adenylate cyclase toxin directs Th17 responses and protection against Bordetella pertussis.

Inflammasome-mediated IL-1beta production is central to the innate immune defects that give rise to certain autoinflammatory diseases and may also be associated with the generation of IL-17-producing CD4(+) T (Th17) cells that mediate autoimmunity. However, the role of the inflammasome in driving adaptive immunity to infection has not been addressed. In this article, we demonstrate that inflammasome-mediated IL-1beta plays a critical role in promoting Ag-specific Th17 cells and in generating protective immunity against Bordetella pertussis infection. Using a murine respiratory challenge model, we demonstrated that the course of B. pertussis infection was significantly exacerbated in IL-1R type I-defective (IL-1RI(-/-)) mice. We found that adenylate cyclase toxin (CyaA), a key virulence factor secreted by B. pertussis, induced robust IL-1beta production by dendritic cells through activation of caspase-1 and the NALP3-containing inflammasome complex. Using mutant toxins, we demonstrate that CyaA-mediated activation of caspase-1 was not dependent on adenylate cyclase enzyme activity but was dependent on the pore-forming capacity of CyaA. In addition, CyaA promoted the induction of Ag-specific Th17 cells in wild-type but not IL-1RI(-/-) mice. Furthermore, the bacterial load was enhanced in IL-17-defective mice. Our findings demonstrate that CyaA, a virulence factor from B. pertussis, promotes innate IL-1beta production via activation of the NALP3 inflammasome and, thereby, polarizes T cell responses toward the Th17 subtype. In addition to its known role in subverting host immunity, our findings suggest that CyaA can promote IL-1beta-mediated Th17 cells, which promote clearance of the bacteria from the respiratory tract.

Relationship between levels of secreted phospholipase A2 groups IIA and X in the airways and asthma severity.

Background Secreted phospholipase A(2) (sPLA(2) ) may be important mediators of asthma, but the specific sPLA(2) s involved in asthma are not known. Objective To evaluate sPLA(2) group IIA, V, and X proteins (sPLA(2) -IIA, sPLA(2) -V, and sPLA(2) -X) in bronchoalveolar lavage (BAL) fluid, BAL cells, and airway epithelial cells of subjects with and without asthma, and examine the relationship between the levels of specific sPLA(2) enzymes and airway inflammation, asthma severity, and lung function. Methods The expression of sPLA(2) -IIA, sPLA(2) -V, and sPLA(2) -X in BAL cells and epithelial brushings was assessed by qPCR. The levels of these sPLA(2) proteins and sPLA(2) activity with and without group II and group X-specific inhibitors were measured in BAL fluid from 18 controls and 39 asthmatics. Results The airway epithelium expressed sPLA(2) -X at higher levels than either sPLA(2) -IIA or sPLA(2) -V, whereas BAL cells expressed sPLA(2) -IIA and sPLA(2) -X at similar levels. The majority of sPLA(2) activity in BAL fluid was attributed to either sPLA(2) -IIA or sPLA(2) -X. After 10-fold concentration of BAL fluid, the levels of sPLA(2) -X normalized to total protein were increased in asthma and were associated with lung function, the concentration of induced sputum neutrophils, and prostaglandin E(2) . The levels of sPLA(2) -IIA were elevated in asthma when normalized to total protein, but were not related to lung function, markers of airway inflammation or eicosanoid formation. Conclusions and Clinical Relevance These data indicate that sPLA(2) -IIA and sPLA(2) -X are the major sPLA(2) s in human airways, and suggest a link between the levels of sPLA(2) -X in the airways and several features of asthma.

Higher pharyngeal epithelial gene expression of angiotensin-converting Enzyme-2 in patients with upper respiratory infection.

We analyzed the expression of ACE2 in the pharyngeal epithelium and examined its relationship with clinical features and serological parameters in patients with upper respiratory infection (URI). The expression level of the ACE2 gene was significantly higher in patients with URI (n = 125) than in healthy control (HC) individuals (n = 52) (p < 0.0001). The ACE2 gene expression level was significantly and positively correlated with age (r=0.1799, p = 0.0447) and body temperature (r=0.1927, p = 0.0427), which may help explain increasing coinfections with SARS-CoV-2 and other respiratory pathogens.

An acquired acyltransferase promotes Klebsiella pneumoniae ST258 respiratory infection.

Klebsiella pneumoniae ST258 is a human pathogen associated with poor outcomes worldwide. We identify a member of the acyltransferase superfamily 3 (atf3), enriched within the ST258 clade, that provides a major competitive advantage for the proliferation of these organisms in vivo. Comparison of a wild-type ST258 strain (KP35) and a Δatf3 isogenic mutant generated by CRISPR-Cas9 targeting reveals greater NADH:ubiquinone oxidoreductase transcription and ATP generation, fueled by increased glycolysis. The acquisition of atf3 induces changes in the bacterial acetylome, promoting lysine acetylation of multiple proteins involved in central metabolism, specifically Zwf (glucose-6 phosphate dehydrogenase). The atf3-mediated metabolic boost leads to greater consumption of glucose in the host airway and increased bacterial burden in the lung, independent of cytokine levels and immune cell recruitment. Acquisition of this acyltransferase enhances fitness of a K. pneumoniae ST258 isolate and may contribute to the success of this clonal complex as a healthcare-associated pathogen.

Acid sphingomyelinase inhibitors normalize pulmonary ceramide and inflammation in cystic fibrosis.

Employing genetic mouse models we have recently shown that ceramide accumulation is critically involved in the pathogenesis of cystic fibrosis (CF) lung disease. Genetic or systemic inhibition of the acid sphingomyelinase (Asm) is not feasible for treatment of patients or might cause adverse effects. Thus, a manipulation of ceramide specifically in lungs of CF mice must be developed. We tested whether inhalation of different acid sphingomyelinase inhibitors does reduce Asm activity and ceramide accumulation in lungs of CF mice. The efficacy and specificity of the drugs was determined. Ceramide was determined by mass spectrometry, DAG-kinase assays, and fluorescence microscopy. We determined pulmonary and systemic Asm activity, neutral sphingomyelinase (Nsm), ceramide, cytokines, and infection susceptibility. Mass spectroscopy, DAG-kinase assays, and semiquantitative immune fluorescence microscopy revealed that a standard diet did not influence ceramide in bronchial respiratory epithelial cells, while a diet with Peptamen severely affected the concentration of sphingolipids in CF lungs. Inhalation of the Asm inhibitors amitriptyline, trimipramine, desipramine, chlorprothixene, fluoxetine, amlodipine, or sertraline restored normal ceramide concentrations in murine bronchial epithelial cells, reduced inflammation in the lung of CF mice and prevented infection with Pseudomonas aeruginosa. All drugs showed very similar efficacy. Inhalation of the drugs was without systemic effects and did not inhibit Nsm. These findings employing several structurally different Asm inhibitors identify Asm as primary target in the lung to reduce ceramide concentrations. Inhaling an Asm inhibitor may be a beneficial treatment for CF, with minimal adverse systemic effects.

Resistance to mucosal lysozyme compensates for the fitness deficit of peptidoglycan modifications by Streptococcus pneumoniae.

The abundance of lysozyme on mucosal surfaces suggests that successful colonizers must be able to evade its antimicrobial effects. Lysozyme has a muramidase activity that hydrolyzes bacterial peptidoglycan and a non-muramidase activity attributable to its function as a cationic antimicrobial peptide. Two enzymes (PgdA, a N-acetylglucosamine deacetylase, and Adr, an O-acetyl transferase) that modify different sites on the peptidoglycan of Streptococcus pneumoniae have been implicated in its resistance to lysozyme in vitro. Here we show that the antimicrobial effect of human lysozyme is due to its muramidase activity and that both peptidoglycan modifications are required for full resistance by pneumococci. To examine the contribution of lysozyme and peptidoglycan modifications during colonization of the upper respiratory tract, competition experiments were performed with wild-type and pgdAadr mutant pneumococci in lysozyme M-sufficient (LysM(+/+)) and -deficient (LysM(-/-)) mice. The wild-type strain out-competed the double mutant in LysM(+/+), but not LysM(-/-) mice, indicating the importance of resistance to the muramidase activity of lysozyme during mucosal colonization. In contrast, strains containing single mutations in either pgdA or adr prevailed over the wild-type strain in both LysM(+/+) and LysM(-/-) mice. Our findings demonstrate that individual peptidoglycan modifications diminish fitness during colonization. The competitive advantage of wild-type pneumococci in LysM(+/+) but not LysM(-/-) mice suggests that the combination of peptidoglycan modifications reduces overall fitness, but that this is outweighed by the benefits of resistance to the peptidoglycan degrading activity of lysozyme.

Saxagliptin: a new dipeptidyl peptidase 4 inhibitor for type 2 diabetes.

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and safety of saxagliptin, a new dipeptidyl peptidase-4 (DPP-4) inhibitor for the treatment of type 2 diabetes. DATA SOURCES: Searches of PubMed (1966-March 2010) and International Pharmacy Abstracts (1970-March 2010) were conducted using the key words saxagliptin, Onglyza, and BMS-477118. A review of bibliographies of retrieved articles was also performed to identify additional references. STUDY SELECTION AND DATA EXTRACTION: All identified studies published in English and involving efficacy and safety of saxagliptin in the treatment of type 2 diabetes were reviewed. DATA SYNTHESIS: Saxagliptin is a competitive inhibitor of DPP-4 that slows the degradation of incretin hormones, thereby stimulating insulin secretion, reducing postprandial glucagon, and decreasing glucose levels. Saxagliptin is well absorbed after oral administration and demonstrates a pharmacokinetic profile that is compatible with once-daily dosing. Clinical trials with saxagliptin monotherapy for the treatment of type 2 diabetes showed a reduction in hemoglobin A(1c) (A1C) of 0.43-0.9%. Saxagliptin has demonstrated similar reductions in A1C when used as add-on therapy with metformin, sulfonylureas, and thiazolidinediones. The combination of saxagliptin and metformin for initial therapy in treatment-naïve patients was associated with greater improvements in A1C than either agent alone. In general, saxagliptin therapy is well tolerated. The most common adverse effects occurring in clinical trials were headache, nasopharyngitis, upper respiratory tract infections, and urinary tract infections. CONCLUSIONS: Saxagliptin is effective as monotherapy or add-on therapy for the management of type 2 diabetes. Because saxagliptin has a higher cost and reduces A1C and other surrogate markers of glucose control to a lesser extent than other well-validated therapies, such as metformin, saxagliptin should be reserved for patients who fail or are intolerant of conventional treatments for type 2 diabetes.

Role of NADPH phagocyte oxidase in host defense against acute respiratory Acinetobacter baumannii infection in mice.

Acinetobacter baumannii is an emerging bacterial pathogen that rapidly develops multiple-drug resistance and is responsible for many nosocomial pulmonary infections. This study investigated the role of the NADPH phagocyte oxidase (phox) and inducible nitric oxide synthase (NOS2) in the host defense against respiratory infection with A. baumannii in mouse models of intranasal A. baumannii infection. gp91(phox-/-) mice showed higher susceptibility to A. baumannii infection than wild-type (WT) C57BL/6 mice, with significantly greater bacterial counts in their lungs (1,000-fold) (P < 0.005) and spleens (10-fold) (P < 0.05). Moreover, all of the gp91(phox-/-) mice succumbed to infection within 48 h. In contrast, only a moderate increase in bacterial burdens was detected in the lungs of NOS2(-/-) mice, and all NOS2(-/-) mice survived infection. Compared to WT mice, the pulmonary influx of inflammatory cells and serum and local inflammatory cytokine/chemokine responses were not obviously impaired at 4 h and were significantly higher at 24 h (P < 0.05) in gp91(phox-/-) mice, but NADPH-deficient neutrophils were unable to control bacterial replication and extrapulmonary dissemination. Thus, NADPH phagocyte oxidase appears to play a crucial role in the neutrophil-mediated host defense against A. baumannii.