G551D cystic fibrosis mice exhibit abnormal regulation of inflammation in lungs and macrophages

Fecal calprotectin in pediatric gastrointestinal diseases: Pros and cons

BACKGROUND

Fecal calprotectin is a valuable biomarker for assessing intestinal inflammation in pediatric gastrointestinal diseases. However, its role, pros, and cons in various conditions must be comprehensively elucidated.

AIM

To explore the role of fecal calprotectin in pediatric gastrointestinal diseases, including its advantages and limitations.

METHODS

A comprehensive search was conducted on PubMed, PubMed Central, Google Scholar, and other scientific research engines until February 24, 2024. The review included 88 research articles, 56 review articles, six meta-analyses, two systematic reviews, two consensus papers, and two letters to the editors.

RESULTS

Fecal calprotectin is a non-invasive marker for detecting intestinal inflammation and monitoring disease activity in pediatric conditions such as functional gastrointestinal disorders, inflammatory bowel disease, coeliac disease, coronavirus disease 2019-induced gastrointestinal disorders, gastroenteritis, and cystic fibrosis-associated intestinal pathology. However, its lack of specificity and susceptibility to various confounding factors pose challenges in interpretation. Despite these limitations, fecal calprotectin offers significant advantages in diagnosing, monitoring, and managing pediatric gastrointestinal diseases.

CONCLUSION

Fecal calprotectin holds promise as a valuable tool in pediatric gastroenterology, offering insights into disease activity, treatment response, and prognosis. Standardized protocols and guidelines are needed to optimize its clinical utility and mitigate interpretation challenges. Further research is warranted to address the identified limitations and enhance our understanding of fecal calprotectin in pediatric gastrointestinal diseases.

Macrophages from gut-corrected CF mice express human CFTR and lack a pro-inflammatory phenotype

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The cftr^tm1unc Tg(FABP-hCFTR) mouse is a commonly-used animal model of CF.

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This mouse expresses human CFTR in the gut to prevent fatal intestinal obstruction.

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Macrophages from this mouse fail to replicate immune dysfunction seen in patient cells.

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We show ectopic expression of human CFTR transgene in macrophages from this CF mouse.

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This may help to explain anomalies in the field related to use of this model.

Macrophages represent prominent immune orchestrators of cystic fibrosis (CF) inflammation and, as such, are an ever-increasing focus of CF research with several reports of intrinsic immune dysfunction related to loss of CFTR activity in macrophages themselves. Animal models of CF have contributed, in no small part, to a deepening of our understanding of the pathophysiology of the disease and towards therapeutic development. A commonly-used animal model in CF research is the Cftr^tm1Unc Tg(FABP-hCFTR) mouse, which displays gut-specific expression of a human CFTR transgene in order to rescue the high rate of early mortality in Cftr-null mice associated with severe intestinal obstruction. We find significant variation in the response to inflammatory challenge of patient macrophages and cells derived from the Cftr^tm1Unc Tg(FABP-hCFTR) mouse and show that macrophages derived from this mouse exhibit aberrant expression of human CFTR. This may contribute to the absence of inflammatory changes in this model.

Increased Prevalence of Celiac Disease in Patients with Cystic Fibrosis: A Systematic Review and Meta-Analysis

Objectives: Immune regulation seems to be altered in cystic fibrosis (CF), thus potentially predisposing patients to developing autoimmune diseases (AID). In this meta-analysis, we aimed to evaluate the prevalence of celiac disease (CeD) among CF patients as by far the most commonly reported autoimmune disease in this population and, secondly, to review the observations on other, less frequently studied autoimmune diseases. Methods: We conducted a systematic literature search for studies that discussed AIDs among CF patients. Following standard selection and data collection, we calculated pooled raw prevalence with 95% confidence intervals (CI) for biopsy-verified CeD and seropositivity. Results: Out of the 21 eligible studies, 15 reported on CeD. Pooled prevalence of biopsy-verified CeD was 1.8% (CI 1.1–2.7%) according to a homogeneous dataset from six prospective, consecutive screening studies, while it proved to be 2.3% (CI 1.1–4.7%) according to a heterogeneous dataset from the other studies. Tissue transglutaminase IgA positivity was detected in 4.5% of CF cases (CI 2.8–6.9%), while tissue transglutaminase IgA–endomysial antibody IgA double positivity was found in 2.4% of them (CI 1.5–3.9%). Findings on other AIDs were strongly limited. Conclusions: The pooled prevalence of CeD in CF seemed to be more than twice as high compared to the global prevalence; therefore, routine screening of CeD could be considered in CF.

Biochemistry of very-long-chain and long-chain ceramides in cystic fibrosis and other diseases: The importance of side chain

Ceramides, the principal building blocks of all sphingolipids, have attracted the attention of many scientists around the world interested in developing treatments for cystic fibrosis, the most common genetic disease of Caucasians. Many years of fruitful research in this field have produced some fundamentally important, yet controversial results. Here, we aimed to summarize the current knowledge on the role of long- and very-long- chain ceramides, the most abundant species of ceramides in animal cells, in cystic fibrosis and other diseases. We also aim to explain the importance of the length of their side chain in the context of stability of transmembrane proteins through a concise synthesis of their biophysical chemistry, cell biology, and physiology. This review also addresses several remaining riddles in this field. Finally, we discuss the technical challenges associated with the analysis and quantification of ceramides. We provide the evaluation of the antibodies used for ceramide quantification and we demonstrate their lack of specificity. Results and discussion presented here will be of interest to anyone studying these enigmatic lipids.

Biochemistry of very-long-chain and long-chain ceramides in cystic fibrosis and other diseases: The importance of side chain

Ceramides, the principal building blocks of all sphingolipids, have attracted the attention of many scientists around the world interested in developing treatments for cystic fibrosis, the most common genetic disease of Caucasians. Many years of fruitful research in this field have produced some fundamentally important, yet controversial results. Here, we aimed to summarize the current knowledge on the role of long- and very-long- chain ceramides, the most abundant species of ceramides in animal cells, in cystic fibrosis and other diseases. We also aim to explain the importance of the length of their side chain in the context of stability of transmembrane proteins through a concise synthesis of their biophysical chemistry, cell biology, and physiology. This review also addresses several remaining riddles in this field. Finally, we discuss the technical challenges associated with the analysis and quantification of ceramides. We provide the evaluation of the antibodies used for ceramide quantification and we demonstrate their lack of specificity. Results and discussion presented here will be of interest to anyone studying these enigmatic lipids.

The impact of impaired macrophage functions in cystic fibrosis disease progression

The underlying cause of morbidity in cystic fibrosis (CF) is the decline in lung function, which results in part from chronic inflammation. Inflammation and infection occur early in infancy in CF and the role of innate immune defense in CF has been highlighted in the last years. Once thought simply to be consumers of bacteria, macrophages have emerged as highly sensitive immune cells that are located at the balance point between inflammation and resolution of this inflammation in CF pathophysiology. In order to assess the potential role of macrophage in CF, we review the evidence that: (1) CF macrophage has a dysregulated inflammatory phenotype; (2) CF macrophage presents altered phagocytosis capacity and bacterial killing; and (3) lipid disorders in CF macrophage affect its function. These alterations of macrophage weaken innate defense of CF patients and may be involved in CF disease progression and lung damage.

Update of faecal markers of inflammation in children with cystic fibrosis

There is evidence of intestinal inflammation in patients with CF. Intestinal inflammation may negatively impact the nutritional status of patient with CF, which adversely affects pulmonary function and survival. This paper provides an up-to-date review of intestinal inflammation in CF and an evaluation of utility of two specific faecal inflammatory markers (S100A12 and calprotectin).

Innate immunity in cystic fibrosis lung disease

Chronic lung disease determines the morbidity and mortality of cystic fibrosis (CF) patients. The pulmonary immune response in CF is characterized by an early and non-resolving activation of the innate immune system, which is dysregulated at several levels. Here we provide a comprehensive overview of innate immunity in CF lung disease, involving (i) epithelial dysfunction, (ii) pathogen sensing, (iii) leukocyte recruitment, (iv) phagocyte impairment, (v) mechanisms linking innate and adaptive immunity and (iv) the potential clinical relevance. Dissecting the complex network of innate immune regulation and associated pro-inflammatory cascades in CF lung disease may pave the way for novel immune-targeted therapies in CF and other chronic infective lung diseases.

Strain-dependent airway hyperresponsiveness and a chromosome 7 locus of elevated lymphocyte numbers in cystic fibrosis transmembrane conductance regulator-deficient mice

We previously observed the lungs of naive BALB/cJ Cftr(tm1UNC) mice to have greater numbers of lymphocytes, by immunohistochemical staining, than did BALB wild type littermates or C57BL/6J Cftr(tm1UNC) mice. In the present study, we initially investigated whether this mutation in Cftr alters the adaptive immunity phenotype by measuring the lymphocyte populations in the lungs and spleens by FACS and by evaluating CD3-stimulated cytokine secretion, proliferation, and apoptosis responses. Next, we assessed a potential influence of this lymphocyte phenotype on lung function through airway resistance measures. Finally, we mapped the phenotype of pulmonary lymphocyte counts in BALB × C57BL/6J F2 Cftr(tm1UNC) mice and reviewed positional candidate genes. By FACS analysis, both the lungs and spleens of BALB Cftr(tm1UNC) mice had more CD3(+) (both CD4(+) and CD8(+)) cells than did littermates or C57BL/6J Cftr(tm1UNC) mice. Cftr(tm1UNC) and littermate mice of either strain did not differ in anti-CD3-stimulated apoptosis or proliferation levels. Lymphocytes from BALB Cftr(tm1UNC) mice produced more IL-4 and IL-5 and reduced levels of IFN-γ than did littermates, whereas lymphocytes from C57BL/6J Cftr(tm1UNC) mice demonstrated increased Il-17 secretion. BALB Cftr(tm1UNC) mice presented an enhanced airway hyperresponsiveness to methacholine challenge compared with littermates and C57BL/6J Cftr(tm1UNC) mice. A chromosome 7 locus was identified to be linked to lymphocyte numbers, and genetic evaluation of the interval suggests Itgal and Il4ra as candidate genes for this trait. We conclude that the pulmonary phenotype of BALB Cftr(tm1UNC) mice includes airway hyperresponsiveness and increased lymphocyte numbers, with the latter trait being influenced by a chromosome 7 locus.

Molecular pathways for intracellular cholesterol accumulation: common pathogenic mechanisms in Niemann-Pick disease Type C and cystic fibrosis

It has been less than two decades since the underlying genetic defects in Niemann-Pick disease Type C were first identified. These defects impair function of two proteins with a direct role in lipid trafficking, resulting in deposition of free cholesterol within late endosomal compartments and a multitude of effects on cell function and clinical manifestations. The rapid pace of research in this area has vastly improved our overall understanding of intracellular cholesterol homeostasis. Excessive cholesterol buildup has also been implicated in clinical manifestations associated with a number of genetically unrelated diseases including cystic fibrosis. Applying knowledge about anomalous cell signaling behavior in cystic fibrosis opens prospects for identifying similar previously unrecognized disease pathways in Niemann-Pick disease Type C. Recognition that Niemann-Pick disease Type C and cystic fibrosis both impair cholesterol regulatory pathways also provides a rationale for identifying common therapeutic targets.

Calcium-modulated chloride pathways contribute to chloride flux in murine cystic fibrosis-affected macrophages

Cystic fibrosis (CF), a common lethal inherited disorder defined by ion transport abnormalities, chronic infection, and robust inflammation, is the result of mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, a cAMP-activated chloride (Cl-) channel. Macrophages are reported to have impaired activity in CF. Previous studies suggest that Cl- transport is important for macrophage function; therefore, impaired Cl- secretion may underlie CF macrophage dysfunction. To determine whether alterations in Cl- transport exist in CF macrophages, Cl- efflux was measured using N-[ethoxycarbonylmethyl]- 6-methoxy-quinolinium bromide (MQAE), a fluorescent indicator dye. The contribution of CFTR was assessed by calculating Cl- flux in the presence and absence of cftr(inh)-172. The contribution of calcium (Ca(2+))-modulated Cl- pathways was assessed by examining Cl- flux with varied extracellular Ca(2+) concentrations or after treatment with carbachol or thapsigargin, agents that increase intracellular Ca(2+) levels. Our data demonstrate that CFTR contributed to Cl- efflux only in WT macrophages, while Ca(2+)-mediated pathways contributed to Cl- transport in CF and WT macrophages. Furthermore, CF macrophages demonstrated augmented Cl- efflux with increases in extracellular Ca(2+). Taken together, this suggests that Ca(2+)-mediated Cl- pathways are enhanced in CF macrophages compared with WT macrophages.

Role of CFTR expressed by neutrophils in modulating acute lung inflammation and injury in mice

Objective and design

Cystic fibrosis transmembrane conductance regulator (CFTR) regulates infection and inflammation. In this study, we investigated whether a lack of functional CFTR in neutrophils would promote lipopolysaccharide (LPS)-induced lung inflammation and injury.

Materials and methods

CFTR-inhibited or F508del-CFTR-mutated neutrophils were stimulated with LPS and cultured to evaluate production of cytokines and NF-κB activation. Wild-type mice were reconstituted with F508del neutrophils or bone marrow and then intratracheally challenged with LPS to observe lung inflammatory response.

Results

Pharmacologic inhibition and genetic mutation of CFTR in neutrophils activated NF-κB and facilitated macrophage inflammatory protein-2 (MIP-2) and tumor necrosis factor-α (TNF-α) production. Wild-type mice reconstituted with F508del neutrophils and bone marrow had more severe lung inflammation and injury after LPS challenge compared to wild-type mice receiving wild-type neutrophils or bone marrow reconstitution.

Conclusions

Lack of functional CFTR in neutrophils can promote LPS-induced acute lung inflammation and injury.

Clinical significance of microbial infection and adaptation in cystic fibrosis

A select group of microorganisms inhabit the airways of individuals with cystic fibrosis. Once established within the pulmonary environment in these patients, many of these microbes adapt by altering aspects of their structure and physiology. Some of these microbes and adaptations are associated with more rapid deterioration in lung function and overall clinical status, whereas others appear to have little effect. Here we review current evidence supporting or refuting a role for the different microbes and their adaptations in contributing to poor clinical outcomes in cystic fibrosis.

Disease-causing mutations in the cystic fibrosis transmembrane conductance regulator determine the functional responses of alveolar macrophages

Alveolar macrophages (AMs) play a major role in host defense against microbial infections in the lung. To perform this function, these cells must ingest and destroy pathogens, generally in phagosomes, as well as secrete a number of products that signal other immune cells to respond. Recently, we demonstrated that murine alveolar macrophages employ the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel as a determinant in lysosomal acidification (Di, A., Brown, M. E., Deriy, L. V., Li, C., Szeto, F. L., Chen, Y., Huang, P., Tong, J., Naren, A. P., Bindokas, V., Palfrey, H. C., and Nelson, D. J. (2006) Nat. Cell Biol. 8, 933-944). Lysosomes and phagosomes in murine cftr(-/-) AMs failed to acidify, and the cells were deficient in bacterial killing compared with wild type controls. Cystic fibrosis is caused by mutations in CFTR and is characterized by chronic lung infections. The information about relationships between the CFTR genotype and the disease phenotype is scarce both on the organismal and cellular level. The most common disease-causing mutation, DeltaF508, is found in 70% of patients with cystic fibrosis. The mutant protein fails to fold properly and is targeted for proteosomal degradation. G551D, the second most common mutation, causes loss of function of the protein at the plasma membrane. In this study, we have investigated the impact of CFTR DeltaF508 and G551D on a set of core intracellular functions, including organellar acidification, granule secretion, and microbicidal activity in the AM. Utilizing primary AMs from wild type, cftr(-/-), as well as mutant mice, we show a tight correlation between CFTR genotype and levels of lysosomal acidification, bacterial killing, and agonist-induced secretory responses, all of which would be expected to contribute to a significant impact on microbial clearance in the lung.

Azithromycin reduces exaggerated cytokine production by M1 alveolar macrophages in cystic fibrosis

Macrophages phagocyte pathogenic microorganisms and orchestrate immune responses by producing a variety of inflammatory mediators. The cystic fibrosis (CF) transmembrane conductance regulator chloride channel has been reported to be of pivotal importance for macrophage functions. The exact phenotype and role of macrophages in CF is still unknown. Alveolar and peritoneal macrophages were monitored in CF mice homozygous for the F508 del mutation and in wild-type control animals. Classical (M1) and alternative (M2) macrophage polarization and responses to LPS from Pseudomonas aeruginosa were investigated, and the effect of azithromycin was examined in both cell populations. We show that alveolar macrophage counts were 1.7-fold higher in CF as compared with wild-type mice. The macrophage-related chemokine, chemokine C-C motif ligand (CCL)-2, was found to be at least 10-fold more abundant in the alveolar space of mutant mice. Cell count and CCL-2 protein levels were also increased in the peritoneal cavity of CF mice. Both M1 and M2 macrophage polarization were significantly enhanced in alveolar and peritoneal cells from F508del-CF mice as compared with control animals. LPS-stimulated expression of proinflammatory mediators, such as nitric oxide synthase-2, IL-1beta, and CCL-2, was increased, whereas anti-inflammatory IL-10 expression was decreased in CF macrophages. Azithromycin, added to cell cultures at 1 mg/liter, significantly reduced proinflammatory cytokine expression (IL-1beta, CCL-2, TNF-alpha) in M1-induced CF and wild-type alveolar macrophages. Our findings indicate that CF macrophages are ubiquitously accumulated, and that these cells are polarized toward classical and alternative activation status. Azithromycin down-regulates inflammatory cytokine production by M1-polarized CF alveolar macrophages.

cAMP-mediated regulation of cholesterol accumulation in cystic fibrosis and Niemann-Pick type C cells

The goal of this study was to identify a mechanism regulating cholesterol accumulation in cystic fibrosis (CF) cells. Both CFTR activation and expression are regulated by the cAMP pathway, and it is hypothesized that a feedback response involving this pathway may be involved in the phenotype of cholesterol accumulation. To examine the role of the cAMP pathway in cholesterol accumulation, we treated two CF model cell lines with the Rp diastereomer of adenosine 3',5'-cyclic monophosphorothioate (Rp-cAMPS) and visualized by filipin staining. Rp-cAMPS treatment eliminated cholesterol accumulation in CF cells, whereas 8-bromo-cAMP treatment led to cholesterol accumulation in wild-type cells. To confirm these findings in an independent model system, we also examined the role of cAMP in modulating cholesterol accumulation in Niemann-Pick type C (NPC) fibroblasts. Expression of the protein related to NPC, NPC1, is also directly regulated by cAMP; therefore, it is postulated that NPC cells exhibit the same cAMP-mediated control of cholesterol accumulation. Cholesterol accumulation in NPC cells also was reduced by the presence of Rp-cAMPS. Expression of beta-arrestin-2 (betaarr2), a marker of cellular response to cAMP signaling, was significantly elevated in CF model cells, Cftr(-/-) MNE, primary tissue obtained by nasal scrapes from CF subjects, and in NPC fibroblasts compared with respective controls.

Animal models of chronic lung infection with Pseudomonas aeruginosa: useful tools for cystic fibrosis studies

Cystic fibrosis (CF) is caused by a defect in the transmembrane conductance regulator (CFTR) protein that functions as a chloride channel. Dysfunction of the CFTR protein results in salty sweat, pancreatic insufficiency, intestinal obstruction, male infertility and severe pulmonary disease. In most patients with CF life expectancy is limited due to a progressive loss of functional lung tissue. Early in life a persistent neutrophylic inflammation can be demonstrated in the airways. The cause of this inflammation, the role of CFTR and the cause of lung morbidity by different CF-specific bacteria, mostly Pseudomonas aeruginosa, are not well understood. The lack of an appropriate animal model with multi-organ pathology having the characteristics of the human form of CF has hampered our understanding of the pathobiology and chronic lung infections of the disease for many years. This review summarizes the main characteristics of CF and focuses on several available animal models that have been frequently used in CF research. A better understanding of the chronic lung infection caused particularly by P. aeruginosa, the pathophysiology of lung inflammation and the pathogenesis of lung disease necessitates animal models to understand CF, and to develop and improve treatment.

Alterations in immune response and PPAR/LXR regulation in cystic fibrosis macrophages

BACKGROUND

Cystic fibrosis (CF) is characterized by an excessive inflammatory response in epithelial cells and macrophages. In CF mice, lung inflammation can be abrogated by oral treatment with docosahexaenoic acid (DHA). Since PPARs and LXRs are important regulators of inflammation and fatty acid metabolism in macrophages, we hypothesized that these pathways are dysregulated in CF macrophages and are corrected with DHA treatment.

METHODS

Peritoneal macrophages were obtained from wild type and cftr(-/-) mice. LPS induced cytokine secretion and NFkappaB activity were analyzed with and without oral DHA treatment. The expression and activity of PPARalpha,gamma, delta and LXRalpha were analyzed by RT-PCR and EMSA.

RESULTS

LPS induced TNFalpha and IL-6 secretion and NFkappaB p65 activity were increased in CF macrophages. This was associated with low basal PPARgamma expression and attenuated LPS induced induction of PPARdelta, LXRalpha and ABCA1. DHA pretreatment in vivo decreased TNFalpha secretion and p65 activity, and increased PPARalpha and gamma expression and function. The effects of DHA could be reproduced by PPAR agonists and blocked by a PPARalpha antagonist.

CONCLUSION

Impaired regulation of nuclear receptors may contribute to the abnormal LPS induced signaling in CF macrophages and is reversed by DHA.

Up-regulation of S100A8 and S100A9 protein in bronchial epithelial cells by lipopolysaccharide

Increased serum levels of the S100A8 (MRP-8) protein have been reported in inflammatory conditions including bacterial infection, arthritis, and cystic fibrosis (CF). This protein is expressed constitutively with S100A9 (MRP-14) in neutrophils and is regulated by inflammatory stimulants. It has been hypothesized that increased inflammatory response to persistent bacterial infection is a major feature of CF lung disease. Therefore, the authors wished to determine the involvement of these two proteins in the innate defense response of the bronchial epithelium to lipopolysaccharide (LPS). Human bronchial epithelial cells (16HBE14o-) and primary bronchial epithelial cells (NHBE) were grown at air-liquid interface (ALI) and stimulated for up to 96 hours with LPS from Pseudomonas aeruginosa. The 16HBE14o- cells responded to LPS with a 2.9-fold increase in S100A8 mRNA production after 12 hours. S100A9 mRNA production was increased by 1.8-fold after 12 hours and 2.9-fold after 24 hours. It was also found that the S100A8 and S100A9 proteins were increased in the secretions of the 16HBE14o- and NHBE cells after LPS stimulation. This finding suggests that S100A8 and S100A9 are involved in the innate defense of the bronchial epithelium.

New insights into pulmonary inflammation in cystic fibrosis

Persistent lower airway infection with inflammation is the major cause of morbidity and mortality in cystic fibrosis. This review examines the recent advances in the understanding of airway inflammation in cystic fibrosis, and focuses on the evidence that pulmonary inflammation is, under some circumstances, disassociated from infection, and the potential implications for therapeutic intervention.

Regulation of chemokine expression by NaCl occurs independently of cystic fibrosis transmembrane conductance regulator in macrophages

Chronic pulmonary inflammation and infection are the leading causes of morbidity and mortality in cystic fibrosis (CF). While the effect of mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) on airways remains controversial, some groups have demonstrated increases in Na(+) and Cl(-) in CF airway surface liquid compared to normal airways. We investigated the consequences of NaCl on pro-inflammatory chemokine and cytokine production by macrophages. Stimulation of mouse macrophages with increasing amounts of NaCl induced macrophage inflammatory protein-2 (MIP-2) and tumor necrosis factor-alpha (TNF-alpha) production. Further, co-incubation of macrophages with NaCl in the presence of either lipopolysaccharide (LPS) or TNF-alpha synergistically increased MIP-2 production. Both the NaCl and NaCl plus LPS responses were partially dependent on endogenous production and autocrine signaling by TNF-alpha. To investigate the role of CFTR in MIP-2 production, we compared the responses of wild-type and DeltaF508 CF mouse macrophages to NaCl and LPS. The responses of macrophages from both strains were indistinguishable. In addition, CFTR mRNA was not expressed in macrophages. Taken together, these findings suggest that NaCl stimulates MIP-2 production by macrophages through a mechanism that is partially dependent on TNF-alpha but independent of macrophage CFTR expression.

Acute Pseudomonas challenge in cystic fibrosis mice causes prolonged nuclear factor-kappa B activation, cytokine secretion, and persistent lung inflammation

BACKGROUND

Cystic fibrosis (CF) is characterized by an excessive and prolonged inflammatory response to Pseudomonas aeruginosa in the lung. There are high levels of cytokines and chemokines and an exaggerated PMN influx causing significant morbidity and mortality.

OBJECTIVE

To compare the kinetics of the inflammatory response with the kinetics of clearance of acute bacterial challenge in the lungs of CF and wild-type (WT) mice.

METHODS

We challenged CF knockout (KO) and WT mice intratracheally with P aeruginosa in suspension and evaluated bacteria counts, nuclear factor-kappaB (NF-kappaB), and inhibitor of NF-kappaB alpha protein (I-kappaBalpha) in lung tissue, cytokines, and PMN in bronchoalveolar lavage (BAL).

RESULTS

Both groups of mice cleared the infection with the same kinetics. CF-KO mice had more PMN in BAL than WT mice. CF-KO mice had high concentrations of proinflammatory cytokines in BAL on days 2 and 4, whereas cytokines in BAL from WT mice were only slightly elevated. CF-KO mice failed to regenerate I-kappaBalpha once it was degraded, and consequently had prolonged and excessive activation of NF-kappaB for the entire 6-day duration of the study. In contrast, WT mice showed only slight NF-kappaB activation, which plateaued at day 4.

CONCLUSION

These data suggest that NF-kappaB is dysregulated in CF lung infection and could be a good target for therapy. Prolonged responses to initial acute infections may contribute to the eventual establishment of chronic persistent inflammation.

CLINICAL IMPLICATIONS

Dysregulation of the I-kappaB/NF-kappaB pathway in cystic fibrosis leads to prolonged cytokine secretion and persistent inflammation in response to acute challenges and may be important in the development of chronic lung inflammation and infection.

Distinct pattern of lung gene expression in theCftr-KO mice developing spontaneous lung disease compared with their littermate controls

Cystic fibrosis (CF) is caused by a defect in the CF transmembrane conductance regulator (CFTR) protein that functions as a chloride channel. Dysfunction of the CFTR protein results in salty sweat, pancreatic insufficiency, intestinal obstruction, male infertility, and severe pulmonary disease. Most of the morbidity and mortality of CF patients results from pulmonary complications. Differences in susceptibility to bacterial infection and variable degree of CF lung disease among CF patients remain unexplained. Many phenotypic expressions of the disease do not directly correlate with the type of mutation in the Cftr gene. Using a unique CF mouse model that mimics aspects of human CF lung disease, we analyzed the differential gene expression pattern between the normal lungs of wild-type mice (WT) and the affected lungs of CFTR knockout mice (KO). Using microarray analysis followed by quantitation of candidate gene mRNA and protein expression, we identified many interesting genes involved in the development of CF lung disease in mice. These findings point to distinct mechanisms of gene expression regulation between mice with CF and control mice.

Expression of S100A8 correlates with inflammatory lung disease in congenic mice deficient of the cystic fibrosis transmembrane conductance regulator

Background

Lung disease in cystic fibrosis (CF) patients is dominated by chronic inflammation with an early and inappropriate influx of neutrophils causing airway destruction. Congenic C57BL/6 CF mice develop lung inflammatory disease similar to that of patients. In contrast, lungs of congenic BALB/c CF mice remain unaffected. The basis of the neutrophil influx to the airways of CF patients and C57BL/6 mice, and its precipitating factor(s) (spontaneous or infection induced) remains unclear.

Methods

The lungs of 20-day old congenic C57BL/6 (before any overt signs of inflammation) and BALB/c CF mouse lines maintained in sterile environments were investigated for distinctions in the neutrophil chemokines S100A8 and S100A9 by quantitative RT-PCR and RNA in situ hybridization, that were then correlated to neutrophil numbers.

Results

The lungs of C57BL/6 CF mice had spontaneous and significant elevation of both neutrophil chemokines S100A8 and S100A9 and a corresponding increase in neutrophils, in the absence of detectable pathogens. In contrast, BALB/c CF mouse lungs maintained under identical conditions, had similar elevations of S100A9 expression and resident neutrophil numbers, but diverged in having normal levels of S100A8.

Conclusion

The results indicate early and spontaneous lung inflammation in CF mice, whose progression corresponds to increased expression of both S100A8 and S100A9, but not S100A9 alone. Moreover, since both C57BL/6 and BALB/c CF lungs were maintained under identical conditions and had similar elevations in S100A9 and neutrophils, the higher S100A8 expression in the former (or suppression in latter) is a result of secondary genetic influences rather than environment or differential infection.

S100A8 chemotactic protein is abundantly increased, but only a minor contributor to LPS-induced, steroid resistant neutrophilic lung inflammation in vivo

Neutrophilic lung inflammation is an essential component of host defense against diverse eukaryotic and prokaryotic pathogens, but in chronic inflammatory lung diseases, such as chronic obstructive lung disease (COPD), severe asthma, cystic fibrosis, and bronchiolitis, it may damage the host. Glucocorticosteroids are widely used in these conditions and in their infectious exacerbations; however, the clinical efficacy of steroids is disputed. In this study, we used a proteomic approach to identify molecules contributing to neutrophilic inflammation induced by transnasal administration of lipopolysaccharide (LPS) that were also resistant to the potent glucocorticosteroid dexamethasone (Dex). We confirmed that Dex was biologically active at both the transcript (suppression of GM-CSF and TNFalphatranscripts) and protein levels (induction of lipocortin) and used 2D-PAGE/MALDI-TOF to generate global expression profiles, identifying six LPS-induced proteins that were Dex resistant. Of these, S100A8, a candidate neutrophil chemotactic factor, was profiled in detail. Steroid refractory S100A8 expression was highly abundant, transcriptionally regulated, secreted into lung lavage fluid and immunohistochemically localized to tissue infiltrating neutrophils. However, in marked contrast to other vascular beds, neutralizing antibodies to S100A8 had only a weak anti-neutrophil recruitment effect and antibodies against the related S100A9 were ineffective. These data highlight the need for extensive in vivo profiling of proteomically identified candidate molecules and demonstrates that S100A8, despite its abundance, resistance to steroids and known chemotactic activity, is unlikely to be an important determinant of LPS-induced neutrophilic lung inflammation in vivo.

Similarity of gene expression patterns in human alveolar macrophages in response to Pseudomonas aeruginosa and Burkholderia cepacia

To determine if differences in the severity of pulmonary infection in cystic fibrosis seen with late isolates of Pseudomonas aeruginosa and Burkholderia cepacia are associated with differences in the initial response of alveolar macrophages (AM) to these pathogens, we assessed gene expression changes in human AM in response to infection with a laboratory strain, early and late clinical isolates of P. aeruginosa, and B. cepacia. Analysis of gene expression changes at the RNA level using oligonucleotide microarrays, following exposure to laboratory P. aeruginosa strain PAK, showed significant (P < 0.01) >2.5-fold upregulation of 42 genes and >2.5-fold downregulation of 45 genes. The majority of the changes in gene expression involved genes as part of inflammatory pathways and signaling systems. Interestingly, similar responses were observed following exposure of AM to early and late clinical isolates of P. aeruginosa, as well as with B. cepacia, suggesting that the more severe clinical outcome of infections with late clinical isolates of P. aeruginosa or with B. cepacia cannot be explained by differences in the early interactions of these organisms with the human AM, as reflected by the similarity of gene expression changes in response to exposure of AM to these pathogens.

Interleukin 8 secretion from monocytes of subjects heterozygous for the deltaF508 cystic fibrosis transmembrane conductance regulator gene mutation is altered

Patients with cystic fibrosis (CF) exhibit an excessive host inflammatory response. The aim of this study was to determine (i) whether interleukin 8 (IL-8) secretion is increased from monocytes from subjects heterozygous as well as homozygous for cystic fibrosis transmembrane conductance regulator (CFTR) mutations and (ii) whether this is due to increased cell surface lipopolysaccharide (LPS) receptors or, alternatively, increased activation of mitogen-activated protein kinases (MAPK). The basal level of IL-8 secretion was higher from monocytes from CF patients than from monocytes from healthy controls (P = 0.02) and obligate heterozygotes (parents of the CF patients). The 50% effective concentrations for LPS-induced IL-8 production for monocytes from both CF patients and obligate heterozygotes were 100-fold lower than those for monocytes from healthy controls (P < 0.05). No differences in the levels of IL-1beta production were seen between these groups. Expression of the LPS surface receptors CD14 and Toll-like receptor 4 were not different between CF patients and healthy controls. In contrast, phosphorylation of the MAPKs p38 and ERK occurred at lower doses of LPS in monocytes from patients heterozygous and homozygous for CFTR mutations. These results indicate that a single allelic CFTR mutation is sufficient to augment IL-8 secretion in response to LPS. This is not a result of increased LPS receptor expression but, rather, is associated with alterations in MAPK signaling.

CFTR: more than just a chloride channel

This review examines the cystic fibrosis transmembrane conductance regulator (CFTR) protein. After summarizing the ion channels regulated by CFTR, the review focuses on the functions of CFTR that do not relate directly to a disease mechanism based on a channelopathy. The key concept is that newly synthesized CFTR has to enter lipid vesicles which bud from the endoplasmic reticulum. This is abnormally low in DeltaF508 CFTR. Normal wild type vesicular CFTR enters a recycling pool of lipid vesicles which transiently dock with the apical membrane only for CFTR to be retrieved shortly after into a sub-apical recycling compartment. This retrieval is abnormally fast in DeltaF508 CFTR. The review discusses the relationship between this process and the difficult topic of fat metabolism and then explores the possible links between abnormal fatty acid turnover and inflammatory cascades that are abnormal in cystic fibrosis. Finally the review concentrates on the emerging functions of a protein kinase (AMP-activated kinase) which is bound near the C terminus of the CFTR protein whose functions could intergrate some of the abnormalities in lipid metabolism that result from mislocalization of CFTR in clinical disease.

Phagocyte-specific calcium-binding S100 proteins as clinical laboratory markers of inflammation

The EF-hand homolog family of S100 proteins comprises the largest group of calcium-binding proteins. Within this S100 family, the phagocyte-specific calcium-binding proteins are pro-inflammatory molecules expressed and secreted by phagocytes, which play a pivotal role within the innate immune system. Although the exact biological functions of these proteins still remain to be defined in greater detail, there is evidence that they are involved in a pro-inflammatory axis associated with various inflammatory conditions. The three members of this group, S100A8, S100A9 and S100A12 are overexpressed at local sites of inflammation. High concentrations are found in synovial fluid, sputum, stool and blood plasma/serum during inflammation. Both the S100A8/S100A9 complex and S100A12 have been proven to be useful as diagnostic markers of inflammation especially in non-infectious inflammatory diseases such as arthritis, chronic inflammatory lung and bowel disease. They indicate phagocyte activation more sensitively than conventional parameters of inflammation. As a consequence, there is a strong correlation to the inflammation of various acute and chronic disorders, making these proteins sensitive parameters for the monitoring of disease activity and response to treatment in individual patients. The phagocyte-specific S100 proteins are able to indicate minimal residual inflammation, which is not detected by other diagnostic tests, and they may even be prospective markers for the outcome of patients. In this review, pro-inflammatory functions of S100 proteins and their usefulness as biomarkers of inflammation are presented.

Role of IL-10 deficiency in excessive nuclear factor-κB activation and lung inflammation in cystic fibrosis transmembrane conductance regulator knockout mice

BACKGROUND

Patients with cystic fibrosis (CF) and CF transmembrane conductance regulator knockout (CF-KO) mice are deficient in pulmonary IL-10 and have excessive inflammatory response to Pseudomonas aeruginosa infection.

OBJECTIVE

We hypothesized that local IL-10 deficiency in the lung was responsible for prolonged and excessive inflammatory responses and observations of inflammation in the absence of infection.

METHODS

To determine whether IL-10 deficiency could account for persistent inflammation in CF mice independent of interactions of bacteria with epithelial cells, we challenged IL-10-knockout (IL-10-KO), CF-KO, and wild-type (WT) mice intratracheally with LPS and determined the effects of IL-10 replacement in CF-KO mice.

RESULTS

In response to LPS, IL-10-KO and CF-KO mice had more neutrophils and proinflammatory cytokines in bronchoalveolar lavage than WT mice. Both types of knockout mice had more profound and prolonged consumption of I-kappaB and increased activation of nuclear factor kappaB (NF-kappaB). Activated NF-kappaB persisted for 6 to 8 hours in CF-KO and IL-10-KO mice but was not detected beyond 2 hours in WT mice. IL-10 treatment of CF-KO mice attenuated the reduction in I-kappaBalpha and activation of NF-kappaB and reduced the excessive inflammation.

CONCLUSION

Similarities in the responses of CF-KO and IL-10-KO mice and correction of excessive responses in CF mice by exogenous IL-10 suggest that deficiency of IL-10 may be responsible for prolonged and excessive inflammatory responses in CF. Because LPS was used as the stimulus, these excessive responses are independent of any possible differences in the interactions of bacteria with CF epithelial cells.

Animal models of cystic fibrosis

Animal models of cystic fibrosis, in particular several different mutant mouse strains obtained by homologous recombination, have contributed considerably to our understanding of CF pathology. In this review, we describe and compare the main phenotypic features of these models. Recent and possible future developments in this field are discussed.

Characteristic multiorgan pathology of cystic fibrosis in a long-living cystic fibrosis transmembrane regulator knockout murine model

The lack of an appropriate animal model with multiorgan pathology characteristic of the human form of cystic fibrosis has hampered our understanding of the pathobiology of the disease. We evaluated multiple organs of congenic C57BL/6J cystic fibrosis transmembrane regulator (Cftr)(-/-) and Cftr(+/+) mice maintained from weaning on a liquid diet then sacrificed between 1 and 24 months of age. The lungs of the Cftr(-/-) animals showed patchy alveolar overdistention, interstitial thickening, and fibrosis, with progression up to 6 months of age. The proximal and distal airway surface was encased with mucus-like material but lacked overt evidence of chronic bacterial infections or inflammation. All Cftr(-/-) animals showed progressive liver disease, with hepatosteatosis, focal cholangitis, inspissated secretions, and bile duct proliferation; after 1 year of age there was progression to focal biliary cirrhosis. The intercalated, intralobular and interlobular ducts and acinar lumina of the exocrine pancreas, the parotid and submaxillary glands of the Cftr(-/-) animals were dilated and filled with inspissated material, as well as mild inflammation and acinar cell drop out. Quantitative measurements of the pancreas showed significant acinar atrophy and increased acinar volume in comparison with age-matched Cftr(+/+) littermates. The ileal lumen and crypts were filled with adherent fibrillar material. After 3 months of age the vas deferens of the Cftr(-/-) animals could not be identified. None of the aforementioned pathological changes were observed in the Cftr(+/+) littermates fed the same liquid diet. We show, for the first time, that long-lived C578L/6J Cftr(-/-) mice develop manifestations of cystic fibrosis-like disease in all pathologically affected organs in the human form of cystic fibrosis.

Expression of S100A12 (EN-RAGE) in cystic fibrosis

BACKGROUND

Chronic airway inflammation and recurrent infections are a core phenomenon in cystic fibrosis (CF). Diagnosing acute infectious exacerbations is difficult in the presence of chronic inflammatory processes. S100A12 exhibits proinflammatory functions via interaction with the multiligand receptor for advanced glycation end products. Blocking this interaction inhibits inflammatory processes in mice.

METHODS

The expression of S100A12 in lung specimens of patients with end stage lung disease of CF was investigated, and S100A12 levels in the serum of patients with acute infectious exacerbations of CF were measured.

RESULTS

Immunohistochemical studies of CF lung biopsy specimens revealed a significant expression of S100A12 by infiltrating neutrophils. High S100A12 levels were found in the sputum of patients with CF, and serum levels of S100A12 during acute infectious exacerbations were significantly increased compared with healthy controls (median 225 ng/ml v 46 ng/ml). After treatment with intravenous antibiotics the mean S100A12 level decreased significantly. There was also a significant difference between S100A12 levels in patients with acute infectious exacerbations and 18 outpatients without exacerbations (median 225 ng/ml v 105 ng/ml).

CONCLUSIONS

S100A12 is extensively expressed at local sites of inflammation in CF. It is a serum marker for acute infectious exacerbations. High local expression of S100A12 suggests that this protein has a proinflammatory role during airway inflammation and may serve as a novel target for anti-inflammatory treatments.

S100A9/S100A8: Myeloid representatives of the S100 protein family as prominent players in innate immunity

Neutrophils are rapidly recruited to sites of inflammation and are thereby at the forefront of the organism's defense against numerous attacks. As unspecific phagocytes, they belong to the so-called innate immunity. Two S100 proteins, namely S100A9 (MRP14) and S100A8 (MRP8), constitute roughly 40% of the cytosolic protein in these cells, implying by their pure abundance an important role in the effector functions of neutrophils. However, despite intense research in the past 15 years, the puzzle that may embed both molecules into the neutrophil/monocyte physiology is still incomplete. One reason might be the conformational variability the S100A9 and S100A8 molecules can adopt. They readily form hetero- and homodimeric, trimeric as well as tetrameric complexes, but they evidently do also exert specific functions as monomers. An ever-increasing body of information suggests that S100A9 plays a prominent role in leukocyte trafficking and arachidonic acid metabolism. In addition, elevated levels of S100A9 and S100A8 in body fluids of inflamed tissues strengthen the view that these molecules are important players in fighting inflammation. The aim of this review is to give an update on the current developments concerning the S100A9/S100A8 molecule in biology and medicine.

Transcriptional adaptation to cystic fibrosis transmembrane conductance regulator deficiency

Cystic fibrosis, the most commonly inherited lethal pulmonary disorder in Caucasians, is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). To identify genomic responses to the presence or absence of CFTR in pulmonary tissues in vivo, microarray analyses of lung mRNAs were performed on whole lung tissue from mice lacking (CFTR(-)) or expressing mouse CFTR (CFTR(+)). Whereas the histology of lungs from CFTR(-) and CFTR(+) mice was indistinguishable, statistically significant increases in the relative abundance of 29 and decreases in 25 RNAs were identified by RNA microarray analysis. Of RNAs whose expression was consistently altered by the absence of CFTR, functional classes of genes influencing gene transcription, inflammation, intracellular trafficking, signal transduction, and ion transport were identified. RNAs encoding the transcription factor CCAAT enhancer-binding protein (CEBP) delta and interleukin (IL) 1beta, both known to regulate CFTR expression, were induced, perhaps indicating adaptation to the lack of CFTR. RNAs mediating lung inflammation including calgranulin-S100 family members, IL-1beta and IL-4, were increased. Likewise, expression of several membrane transport proteins that interact directly with CFTR were increased, suggesting that CFTR-protein complexes initiate genomic responses. Absence of CFTR influenced the expression of genes modulating diverse pulmonary cell functions that may ameliorate or contribute to the pathogenesis of CF.

Primary inflammation in human cystic fibrosis small airways

Most cystic fibrosis (CF) patients die of lung failure, due to the combined effects of bacterial infection, neutrophil-mediated inflammation, and airway obstruction by hyperviscous mucus. To this day, it remains unclear where and how this pathological vicious circle is initiated in vivo. In particular, it has proven difficult to investigate whether inflammatory pathways are dysregulated in CF airways independently of infection. Also, the relative involvement of large (tracheobronchial) vs. small (bronchiolar) airways in CF pathophysiology is still unclear. To help address these issues, we used an in vivo model based on the maturation of human fetal CF and non-CF small airways in severe combined immunodeficiency mice. We show that uninfected mature CF small airway grafts, but not matched non-CF controls, undergo time-dependent neutrophil-mediated inflammation, leading to progressive lung tissue destruction. This model of mature human small airways provides the first clear-cut evidence that, in CF, inflammation may arise at least partly from a primary defect in the regulation of neutrophil recruitment, independently of infection.

Characterization of LPS-induced lung inflammation in cftr-/- mice and the effect of docosahexaenoic acid

The mechanism by which Pseudomonas causes excessive inflammation in the cystic fibrosis lung is unclear. We have reported that arachidonic acid is increased and docosahexaenoic acid (DHA) decreased in lung, pancreas, and ileum from cftr-/- mice. Oral DHA corrected this defect and reversed the pathology. To determine which mediators regulate inflammation in lungs from cftr-/- mice and whether inhibition occurs with DHA, cftr-/- and wild-type (WT) mice were exposed to aerosolized Pseudomonas lipopolysaccharide (LPS). After 2 days of LPS, tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-2, and KC levels in bronchoalveolar lavage fluid were increased in cftr-/- compared with WT mice and not suppressed by pretreatment with oral DHA. Neutrophil levels were not different between cftr-/- and WT mice. After 3 days of aerosolized LPS, neutrophil concentration, TNF-alpha, and the eicosanoids 6-keto-PGF1alpha, PGF2alpha, PGE2, and thromboxane B2 were all increased in bronchoalveolar lavage fluid from cftr-/- mice compared with WT controls. Oral DHA had no significant effect on TNF-alpha levels in cftr-/- mice. In contrast, neutrophils and eicosanoids were decreased in cftr-/- but not in WT mice treated with DHA, indicating that the effects of DHA on these inflammatory parameters may be related to correction of the membrane lipid defect.

Functional IL-10 deficiency in the lung of cystic fibrosis (cftr(-/-)) and IL-10 knockout mice causes increased expression and function of B7 costimulatory molecules on alveolar macrophages

Alveolar macrophages are poor APCs that only minimally express B7 costimulatory molecules. Because our previous data suggest that bronchial epithelial cells constitutively secrete IL-10, and IL-10 inhibits B7 expression in vitro, we hypothesized that this IL-10 is responsible for suppressing B7 expression on macrophages that enter the airways. Furthermore, because we have shown that cystic fibrosis (CF) lungs are deficient in IL-10, we hypothesized that bronchoalveolar macrophages (BALMs) from cystic fibrosis transmembrane conductance regulator (CFTR)(-/-) as well as IL-10(-/-) mice might express increased B7. Immunofluorescence for B7 was positive on BALMs from CF patients and CFTR(-/-) and IL-10(-/-) mice, but was negative on controls. FACS showed that 63.9% of BALMs from IL-10(-/-) mice were B7-1 positive, as were 67.4% of BALMs from CFTR(-/-) mice, whereas <7% of BALMs from wild-type controls were positive. Using BALMs to costimulate splenic T cells with anti-CD3 as a mitogen showed 9202 +/- 2107 cpm [(3)H]thymidine incorporation for BALMs from IL-10(-/-) mice and 4082 +/- 1036 cpm for BALMs from CFTR(-/-) mice, but <200 cpm with BALMs from either type of +/+ mouse. Treatment of CFTR(-/-) mice with recombinant mouse IL-10 reduced the B7 expression and costimulatory activity of the BALMs. These data suggest that the IL-10 secreted in the healthy lung may be responsible for the absence of B7 and poor costimulatory activity of BALMs and that reductions of pulmonary IL-10 in CF may enhance B7 expression and local immune responses.

Mouse models of cystic fibrosis

The development of mouse models for cystic fibrosis has provided the opportunity to dissect disease pathogenesis, correlate genotype and phenotype, study disease-modifying genes and develop novel therapeutics. This review discusses the successes and the challenges encountered in characterizing and optimizing these models.

Novel intra- and inter-molecular sulfinamide bonds in S100A8 produced by hypochlorite oxidation

Hypochlorite is a major oxidant generated when neutrophils and macrophages are activated at inflammatory sites, such as in atherosclerotic lesions. Murine S100A8 (A8) is a major cytoplasmic protein in neutrophils and is secreted by macrophages in response to inflammatory stimuli. After incubation with reagent HOCl for 10 min, approximately 85% of A8 was converted to 4 oxidation products, with electrospay ionization mass spectrometry masses of m/z 10354, 10388, 10354 +/- 1, and 20707 +/- 3. All were resistant to reduction by dithiothreitol. Initial formation of a reactive Cys sulfenic acid intermediate was demonstrated by the rapid conjugation of 5,5-dimethyl-1,3-cyclohexanedione (dimedone) to HOCl-treated A8 to form stable adducts. Matrix-assisted laser desorption-reflectron time of flight peptide mass fingerprinting of isolated oxidation products confirmed the mass additions observed in the full-length proteins. Both Met(36/73) were converted to Met(36/73) sulfoxides. An additional product with an unusual mass addition of m/z 14 (+/-0.2) was identified and corresponded to the addition of oxygen to Cys(41), conjugation to various epsilon-amines of Lys(6), Lys(34/35), or Lys(87) with loss of dihydrogen and formation of stable intra- or inter-molecular sulfinamide cross-links. Specific fragmentations identified in matrix-assisted laser desorption-post source decay spectra and low energy collisional-induced dissociation tandem mass spectroscopy spectra of sulfinamide-containing digest peptides confirmed Lys(34/35) to Cys(41) sulfinamide bonds. HOCl oxidation of mutants lacking Cys(41) (Ala(41)S100A8) or specific Lys residues (e.g. Lys(34/35), Ala(34/35)S100A8) did not form sulfinamide cross-links. HOCl generated by myeloperoxidase and H(2)O(2) and by phorbol 12-myristate 13-acetate-activated neutrophils also formed these products(.) In contrast to the disulfide-linked dimer, oxidized monomer retained normal chemotactic activity for neutrophils. Sulfinamide bond formation represents a novel oxidative cross-linking process between thiols and amines and may be a general consequence of HOCl protein oxidation in inflammation not identified previously. Similar modifications in other proteins could potentially regulate normal and pathological processes during aging, atherogenesis, fibrosis, and neurogenerative diseases.

G551D CF mice display an abnormal host response and have impaired clearance of Pseudomonas lung disease

Several cystic fibrosis (CF) mouse models demonstrate an increased susceptibility to Pseudomonas aeruginosa lung infection, characterized by excessive inflammation and high rates of mortality. Here we developed a model of chronic P. aeruginosa lung disease in mice homozygous for the murine CF transmembrane conductance regulator G551D mutation that provides an excellent model for CF lung disease. After 3 days of infection with mucoid P. aeruginosa entrapped in agar beads, the G551D animals lost substantially more body weight than non-CF control animals and were less able to control the infection, harboring over 40-fold more bacteria in the lung. The airways of infected G551D animals contained altered concentrations of the inflammatory mediators tumor necrosis factor-alpha, KC/N51, and macrophage inflammatory protein-2 during the first 2 days of infection, suggesting that an ineffective inflammatory response is partly responsible for the clearance defect.

Role of cystic fibrosis transmembrane conductance regulator in pulmonary clearance of Pseudomonas aeruginosa in vivo

Cystic fibrosis (CF)2 is a fatal genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) that is commonly associated with chronic pulmonary infections with mucoid Pseudomonas aeruginosa (PA). To test the hypothesis that CFTR plays a direct role in PA adhesion and clearance, we have used mouse lines expressing varying levels of human (h) or mouse (m) CFTR. A subacute intratracheal dose of 3 x 10(6) bacteria was cleared with similar kinetics in control wild-type (WT) and transgenic mice overexpressing hCFTR in the lung from the surfactant protein C (SP-C) promoter (SP-C-hCFTR+/-). In a second series of experiments, the clearance of an acute intratracheal dose of 1.5 x 10(7) PA bacteria was also similar in WT, hemizygous SP-C-hCFTR+/-, and bitransgenic gut-corrected FABP-hCFTR+/+-mCFTR-/-, the latter lacking expression of mCFTR in the lung. However, a small but significant decrease in bacterial killing was observed in lungs of homozygote SP-C-hCFTR+/+ mice. Lung pathology in both WT and SP-C-hCFTR+/+ mice was marked by neutrophilic inflammation and bacterial invasion of perivascular and subepithelial compartments. Bacteria were associated primarily with leukocytes and were not associated with alveolar type II or bronchiolar epithelial cells, the cellular sites of SP-C-hCFTR+/+ transgene expression. The results indicate that there is no direct correlation between levels of CFTR expression and bacterial clearance or association of bacteria with epithelial cells in vivo.