Animal models to study these mechanisms are limited. This study investigated the effects of single vs. repetitive dust-induced airway inflammation in mice by intranasal exposure method. Mice were exposed to swine facility dust extract (DE) or saline once and once daily for 1 and 2 wk. Dust exposure resulted in increased bronchoalveolar lavage fluid neutrophils and macrophages after single and repetitive exposures. Lavage fluid TNF␣, IL-6, keratinocyte chemoattractant, and macrophage inflammatory protein-2 were significantly increased after single and repetitive dust exposures, but were dampened in 2-wk dust-exposed mice compared with single exposure. Dust exposure induced PKC␣ and -ε activation in isolated tracheal epithelial cells but were dampened with repetitive exposures. Ex vivo stimulation of alveolar macrophages from 2-wk animals demonstrated reduced cytokine responsiveness and phagocytic ability. Significant lung pathology occurred with development of mixed mononuclear cellular aggregates (T and B lymphocytes, phagocytes) after repetitive dust exposure, a novel observation. Airway hyperresponsiveness to methacholine occurred after single dust exposure but resolved after 2 wk. Collectively, intranasal exposure to DE results in significant lung inflammatory and pathological responses marked by a modulated innate immune response to single and repetitive dust exposures that is associated with PKC activity.

Ig class switch recombination (CSR) and somatic hypermutation serve to diversify antibody responses and are orchestrated by the activity of activation-induced cytidine deaminase and many proteins involved in DNA repair and genome surveillance. Msh5, a gene encoded in the central MHC class III region, and its obligate heterodimerization partner Msh4 have a critical role in regulating meiotic homologous recombination and have not been implicated in CSR. Here, we show that MRL/lpr mice carrying a congenic H-2 b/b MHC interval exhibit several abnormalities regarding CSR, including a profound deficiency of IgG3 in most mice and long microhomologies at Ig switch (S) joints. We found that Msh5 is expressed at low levels on the H-2 b haplotype and, importantly, a similar long S joint microhomology phenotype was observed in both Msh5 and Msh4-null mice. We also present evidence that genetic variation in MSH5 is associated with IgA deficiency and common variable immune deficiency (CVID) in humans. One of the human MSH5 alleles identified contains two nonsynonymous polymorphisms, and the variant protein encoded by this allele shows impaired binding to MSH4. Similar to the mice, Ig S joints from CVID and IgA deficiency patients carrying disease-associated MSH5 alleles show increased donor/acceptor microhomology, involving pentameric DNA repeat sequences and lower mutation rates than controls. Our findings suggest that Msh4/5 heterodimers contribute to CSR and support a model whereby Msh4/5 promotes the resolution of DNA breaks with low or no terminal microhomology by a classical nonhomologous end-joining mechanism while possibly suppressing an alternative microhomology-mediated pathway.immunoglobulin subclass deficiency ͉ mismatch repair ͉ Msh4 A fter appropriate stimulation, B cells undergo class switch recombination (CSR), whereby the functionally rearranged V(D)J DNA segment is recombined with a downstream Ig constant region segment. The biochemistry of CSR is complex and involves the B cell-specific gene activation-induced cytidine deaminase, which initiates both CSR and somatic hypermutation (1). CSR also requires many ubiquitously expressed genes important for detecting DNA mismatches and breaks and regulating DNA repair (2). CSR occurs at specific DNA segments called switch (S) regions, which lie upstream of each constant region and contain hotspots for activation-induced cytidine deaminase-mediated cytosine deamination. The ligation of the S region with the downstream S regions is carried out by protein factors that comprise the nonhomologous end joining machinery for DNA repair (1, 2).Mismatch repair proteins play a critical role in safeguarding genetic stability. The key proteins for initiation of eukaryotic mismatch repair are homologues of bacterial MutS and MutL. In mammals, there are five MutS (Msh2, Msh3, Msh4, Msh5, and Msh6) and four MutL (Mlh1, Mlh3, Pms1, and Pms2) homologues. Each Mut homologue acts at the DNA repair or recombination site by forming heterodimers; Msh2-Msh6 (MutS␣), Msh2-Msh3 (MutS␤), M...

Ciliated epithelium represents the first line of host defense against lung infection. Most alcoholics smoke and are at high risk for developing lung infections. We reported that cigarette smoke activates protein kinase C (PKC) and alcohol desensitizes ciliary beat frequency (CBF) to beta-agonists in bovine bronchial epithelial cells in vitro. The combined effect of smoke and alcohol exposure on mouse ciliated tracheal epithelium has not been studied in vivo. We hypothesized that previously observed in vitro effects of smoke and alcohol exposure could be replicated in vivo. Female C57BL/6 mice were exposed to whole body cigarette smoke only, 20% alcohol ad libitum in drinking water only, or the combination of cigarette smoke plus alcohol for 6 wk. Bronchoalveolar lavage (BAL) cell populations, CBF, and airway kinase activity were assessed. Total BAL cells were decreased in animals exposed to alcohol alone and increased in animals exposed to smoke alone. Mice receiving smoke and alcohol had cell levels similar to smoke alone. Baseline CBF was not affected in any group; however, isoproterenol stimulation of CBF was blunted by alcohol exposure and actually slowed below baseline in the smoke plus alcohol group. Isoproterenol-induced PKA activity was inhibited in mice receiving alcohol independent of smoke exposure. Smoke activated PKC independent of alcohol. The isoproterenol-induced slowing below baseline of CBF after combined smoke and alcohol exposure demonstrates a novel ciliary impairment likely related to the combination of alcohol-mediated PKA desensitization and smoke-stimulated PKC activation, possibly through acetaldehyde present in the vapor phase of cigarette smoke.

The absence of Df and AP activation is protective against the development of proliferative renal disease in MRL/lpr mice suggesting the similar effect of Bf deficiency in MRL/lpr mice was also due to the lack of AP activation.

In this study the authors compared the affect of vapor phase cigarette smoke (CS) versus cigarette smoke extract (CSE) on the lungs and upper airway of C57BL/6 mice. The authors found that CSE treatment significantly increased neutrophil influx (P < .001), baseline ciliary beat frequency (CBF) (P < .05), and protein kinase C activity compared to CS and controls. Isoproterenol increased CBF with CS exposure, but decreased CBF with CSE (P < .01). Isoproterenol increased protein kinase A (PKA) activity in all groups except CSE. CSE exposure induced inflammatory cell bronchiolitis. These data indicate that CSE exposure has differential effects on the lungs and tracheal epithelium compared to CS exposure.Ciliary motility provides the driving force for mucociliary clearance. Normal function of the airway mucociliary clearance system prevents the attachment and colonization of pulmonary pathogens in the upper airways. Mucociliary dysfunction caused by impaired ciliary motility results in mucus accumulation, airway obstruction, and bacterial colonization, increasing the likelihood of infection in the lower airway [1][2][3]. Mucociliary clearance is affected by exposure to a number of environmental agents [4,5], including cigarette smoke. Exposure to cigarette smoke (CS) has been linked to the development of lung cancer, emphysema, chronic bronchitis, and chronic obstructive pulmonary disease (COPD) [6]. Smokers are at a higher risk for pulmonary infection [7]. Chronic exposure to tobacco smoke is associated with increased ciliary abnormality [8] and reduced mucociliary clearance [9]. The increased risk for infection seen in smokers may be due to alterations in ciliary function in the upper airway.Several studies have revealed that ciliary activity is controlled by phosphorylation of axonemal proteins [10][11][12]. Protein kinase C (PKC) and cyclic adenosine monophosphate (CAMP)-Address correspondence to Todd A. Wyatt, PhD, University of Nebraska Medical Center, 985300 Nebraska Medical Center, Omaha, NE 68198-5300, USA. E-mail: twyatt@unmc.edu. NIH Public Access Author ManuscriptExp Lung Res. Author manuscript; available in PMC 2007 November 21. Published in final edited form as:Exp Lung Res. 2006 ; 32(3-4): 99-118. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript dependent protein kinase (PKA) are important regulators of airway ciliary beat frequency (CBF). Agents that increase PKC are associated with decreased CBF [13][14][15]. Alternatively, agents associated with increased CBF also increase PKA activity [16]. In past studies, we have shown that exposure of ciliated epithelial cells to cigarette smoke extract (CSE) in culture and whole cigarette smoke in vivo induces an increase in epithelial cell PKC activity [15,[17][18][19]. Many animal models of exposure to cigarette smoke components exist. Most recently, Miller and colleagues have developed a method of exposure consisting of intranasal administration of CSE [20]. This method was shown to induce an inflammatory response similar to ...