The metalloproteinase ADAM‐12 regulates bronchial epithelial cell proliferation and apoptosis

Abstract. Objectives: The ADAMs (a disintegrin and metalloproteinase) enzymes compose a family of membrane‐bound proteins characterized by their multi‐domain structure and ADAM‐12 expression is elevated in human non‐small cell lung cancers. The aim of this study was to investigate the roles played by ADAM‐12 in critical steps of bronchial cell transformation during carcinogenesis. Materials and methods: To assess the role of ADAM‐12 in tumorigenicity, BEAS‐2B cells were transfected with a plasmid encoding human full‐length ADAM‐12 cDNA, and then the effects of ADAM‐12 overexpression on cell behaviour were explored. Treatment of clones with heparin‐binding epidermal growth factor (EGF)‐like growth factor (HB‐EGF) neutralizing antibodies as well as an EGFR inhibitor allowed the dissection of mechanisms regulating cell proliferation and apoptosis. Results: Overexpression of ADAM‐12 in BEAS‐2B cells promoted cell proliferation. ADAM‐12 overexpressing clones produced higher quantities of HB‐EGF in their culture medium which may rely on membrane‐bound HB‐EGF shedding by ADAM‐12. Targeting HB‐EGF activity with a neutralizing antibody abrogated enhanced cell proliferation in the ADAM‐12 overexpressing clones. In sharp contrast, targeting of amphiregulin, EGF or transforming growth factor‐α failed to influence cell proliferation; moreover, ADAM‐12 transfectants were resistant to etoposide‐induced apoptosis and the use of a neutralizing antibody against HB‐EGF activity restored rates of apoptosis to be similar to controls.Conclusions: ADAM‐12 contributes to enhancing HB‐EGF shedding from plasma membranes leading to increased cell proliferation and reduced apoptosis in this bronchial epithelial cell line.     

Human nasal myiasis due to Oestrus ovis]

One case of human nasal myiasis caused by second and third instar larvae of Oestrus ovis was observed in Lille (North France). Oestrosis is a common myiasis of sheep and goats in Mediterranean and Tropical countries. The authors examine the oestrosis pathogenesis in the usual host (sheep) or in humans, and analyse the epidemiology, the symptomatology and the treatment of human oestrosis.     

Comparative analysis of the Salmonella typhi and Escherichia coli ompC genes

The nucleotide (nt) sequence of the gene encoding the Salmonella typhi OmpC outer membrane protein, and its deduced amino acid (aa) sequence are presented here. The S. typhi ompC gene consists of an open reading frame of 1134 nt, corresponding to a protein of 378 aa; with a 21-aa signal peptide. This protein is 11 aa longer than Escherichia coli OmpC, but it has an identical leader peptide. The mature OmpC sequence shows 79% similarity for both bacteria at the aa level, and 77% similarity at the nt level. Seven main variable regions in the OmpC protein were identified. Five of them correspond to hydrophilic regions and contain aa observed most frequently in turn configurations in soluble proteins. This suggests that these aa stretches could be located on the exterior of the outer membrane. To probe into the genus and species specificity of the main variable regions, we have constructed complementary oligodeoxyribonucleotides. The use of one of them with a small number of DNA samples is illustrated here; no restriction fragment length polymorphism or nt sequence heterogeneity could be found between S. typhi and Salmonella typhimurium.     

The ecology of the calanoid copepod Eurytemora affinis in salt marsh tide pools

We describe selected aspects of the ecology of the copepod Eurytemora affinis in tide pools of an inland salt marsh near L'Isle-Verte, Québec along the southern shore of the St. Lawrence estuary. E. affinis performed daily horizontal migrations moving from the centers of pools to the banks and into dense algae. Male E. affinis were mainly found in the center of the pools during twilight (21 : 00 hrs) and in dense algae in daylight (12: 00 hrs) whereas most females and copepodites were found near the banks at all three sampling periods. Although these daily movements among sites may have minimized predation by diurnally foraging sticklebacks (Pisces: Gasterosteidae), other explanations for the movements can not be excluded. We also quantified the effects of fish predation upon the population structure of E. affinis. Densities of all stages (nauplius, copepodite, adult) were significantly lower in pools with fish than in pools without fish. Female E. affinis were significantly smaller (mean length) in pools with fish than in pools without fish, indicating that the sticklebacks selectively ate larger females. Male-biased sex ratios were found in both types of pools, which excluded the possibility that biased ratios in this species are caused by selective predation upon the females.     

Colonic Inflammation in Mice Is Improved by Cigarette Smoke through iNKT Cells Recruitment

Cigarette smoke (CS) protects against intestinal inflammation during ulcerative colitis. Immunoregulatory mechanisms sustaining this effect remain unknown. The aim of this study was to assess the effects of CS on experimental colitis and to characterize the intestinal inflammatory response at the cellular and molecular levels. Using the InExpose® System, a smoking device accurately reproducing human smoking habit, we pre-exposed C57BL/6 mice for 2 weeks to CS, and then we induced colitis by administration of dextran sodium sulfate (DSS). This system allowed us to demonstrate that CS exposure improved colonic inflammation (significant decrease in clinical score, body weight loss and weight/length colonic ratio). This improvement was associated with a significant decrease in colonic proinflammatory Th1/Th17 cytokine expression, as compared to unexposed mice (TNF (p = 0.0169), IFNγ (p<0.0001), and IL-17 (p = 0.0008)). Smoke exposure also induced an increased expression of IL-10 mRNA (p = 0.0035) and a marked recruitment of iNKT (invariant Natural Killer T; CD45+ TCRβ+ CD1d tetramer+) cells in the colon of DSS-untreated mice. Demonstration of the role of iNKT cells in CS-dependent colitis improvement was performed using two different strains of NKT cells deficient mice. Indeed, in Jα18KO and CD1dKO animals, CS exposure failed to induce significant regulation of DSS-induced colitis both at the clinical and molecular levels. Thus, our study demonstrates that iNKT cells are pivotal actors in the CS-dependent protection of the colon. These results highlight the role of intestinal iNKT lymphocytes and their responsiveness to environmental stimuli. Targeting iNKT cells would represent a new therapeutic way for inflammatory bowel diseases.     

Cadmium reduces the efficiency of Sindbis virus replication in human cells and promotes their survival by inhibiting apoptosis

Arthritogenic alphaviruses are emerging arthropod-borne viruses that occasionally cause sporadic to global outbreaks all over the world. Many environmental factors including xenobiotics have been identified as capable of influencing the spread, the susceptibility and the outcome of viral infection. Among them cadmium is a toxic non-essential heavy metal and a prevalent environmental contaminant. In the present study we evaluated the effect of cadmium exposure on alphavirus infection in vitro. We infected Human Embryonic Kidney (HEK) 293 cells in the presence of cadmium chloride (CdCl₂) with Sindbis virus. Cell viability, apoptosis and viral growth were then examined. Our data show that effective doses of cadmium decreased the virus mediated-cell death by inhibition of apoptosis. Moreover, virus growth in HEK 293 cells was also reduced by CdCl₂ treatment. Altogether our results demonstrate that cadmium triggers a protective response which renders HEK 293 cells resistant against Sindbis virus infection.     

Segregostat: a novel concept to control phenotypic diversification dynamics on the example of Gram-negative bacteria

Controlling and managing the degree of phenotypic diversification of microbial populations is a challenging task. This task not only requires detailed knowledge regarding diversification mechanisms but also advanced technical set-ups for the real-time analyses and control of population behaviour on single-cell level. In this work, set-up, design and operation of the so called segregostat are described which, in contrast to a traditional chemostat, allows the control of phenotypic diversification of microbial populations over time. Two exemplary case studies will be discussed, i.e. phenotypic diversification dynamics of Eschericia coli and Pseudomonas putida based on outer membrane permeabilization, emphasizing the applicability and versatility of the proposed approach. Upon nutrient limitation, cell population tends to diversify into several subpopulations exhibiting distinct phenotypic features (non-permeabilized and permeabilized cells). Online analysis leads to the determination of the ratio between cells in these two states, which in turn triggers the addition of glucose pulses in order to maintain a predefined diversification ratio. These results prove that phenotypic diversification can be controlled by means of defined pulse-frequency modulation within continuously running bioreactor set-ups. This lays the foundation for systematic studies, not only of phenotypic diversification but also for all processes where dynamics single-cell approaches are required, such as synthetic co-culture processes.     

Characterization of bacterial diversity in pulque, a traditional Mexican alcoholic fermented beverage, as determined by 16S rDNA analysis

The bacterial diversity in pulque, a traditional Mexican alcoholic fermented beverage, was studied in 16S rDNA clone libraries from three pulque samples. Sequenced clones identified as Lactobacillus acidophilus, Lactobacillus strain ASF360, L. kefir, L. acetotolerans, L. hilgardii, L. plantarum, Leuconostoc pseudomesenteroides, Microbacterium arborescens, Flavobacterium johnsoniae, Acetobacter pomorium, Gluconobacter oxydans, and Hafnia alvei, were detected for the first time in pulque. Identity of 16S rDNA sequenced clones showed that bacterial diversity present among pulque samples is dominated by Lactobacillus species (80.97%). Seventy-eight clones exhibited less than 95% of relatedness to NCBI database sequences, which may indicate the presence of new species in pulque samples.