Lung development in laminin γ2 deficiency: abnormal tracheal hemidesmosomes with normal branching morphogenesis and epithelial differentiation

BACKGROUND: Laminin γ2 (Lamc2), one of the polypeptides in laminin-332 (laminin-5), is prominent in the basement membrane of alveolar walls and airways of developing and adult lung. Laminins are important for lung morphogenesis and based on its localization, a function for laminin γ2 in lung development has been hypothesized. Targeted deletion of the laminin γ2 gene in mice results in skin blistering and neonatal death at 3–5 days after birth due to failure to thrive. METHODS: Examination of lung development in Lamc2-/- mice through 1–2 days postnatal was accomplished by morphometric analysis, lung bud culture, electron microscopy, immunohistochemical and immunofluorescence staining. RESULTS: Compared to littermate controls, Lamc2-/- lungs were similar in morphology during embryonic life. At post-natal day 1–2, distal saccules were mildly dilated by chord length measurements. Epithelial differentiation as evaluated by immunohistochemical staining for markers of ciliated cells, Clara cells, alveolar type I cells and alveolar type II cells did not reveal a difference between Lamc2-/- and littermate control lungs. Likewise, vascular development, smooth muscle cell differentiation, and elastic fiber formation looked similar, as did airway basement membrane ultrastructure. Branching morphogenesis by lung bud culture was similar in Lamc2-/- and littermate control lungs. Since laminin-332 is important for hemidesmosome formation, we examined the structure of tracheal hemidesmosomes by transmission electron microscopy. Compared to littermate controls, Lamc2-/- tracheal hemidesmosomes were less organized and lacked the increased electron density associated with the basement membrane abutting the hemidesmosome. CONCLUSION: These findings indicate that laminin γ2 and laminin-332, despite their prominence in the lung, have a minimal role in lung development through the saccular stage

Prevalence of hepatitis C in drug users in Flanders: determinants and geographic differences

The prevalence of hepatitis C and related risk factors in drug users were compared in two geographic regions in Belgium, the city of Antwerp and the mixed urban-rural area of Limburg. All 310 participants were surveyed and screened for hepatitis B, hepatitis C and HIV. Prevalence rates of anti-HCV, anti-HBc and anti-HIV were 71, 62 and 4% in Antwerp and 46, 21 and 0% in Limburg respectively. Injecting drug use, duration of injecting drug use, work as a commercial sex-worker, originating from Turkey or Northern Africa, marginalization and anti-HBc positivity were identified as independent predictors for hepatitis C infection. In this study an important difference in HCV seroprevalence among drug users in a methadone maintenance programme across two geographic regions in Belgium was demonstrated. This was explained not only by variations in drug-related risk behaviour, but also by differences in sexual risk behaviour and socio-economic status.status: publishe

Prevalence of hepatitis C in drug users in Flanders: determinants and geographic differences.

The prevalence of hepatitis C and related risk factors in drug users were compared in two geographic regions in Belgium, the city of Antwerp and the mixed urban-rural area of Limburg. All 310 participants were surveyed and screened for hepatitis B, hepatitis C and HIV. Prevalence rates of anti-HCV, anti-HBc and anti-HIV were 71, 62 and 4% in Antwerp and 46, 21 and 0% in Limburg respectively. Injecting drug use, duration of injecting drug use, work as a commercial sex-worker, originating from Turkey or Northern Africa, marginalization and anti-HBc positivity were identified as independent predictors for hepatitis C infection. In this study an important difference in HCV seroprevalence among drug users in a methadone maintenance programme across two geographic regions in Belgium was demonstrated. This was explained not only by variations in drug-related risk behaviour, but also by differences in sexual risk behaviour and socio-economic status

The basement membrane protein BM-600/nicein codistributes with kalinin and the integrin alpha 6 beta 4 in human cultured keratinocytes

The observation is reported that in low-passage human keratinocyte colonies cultured under conditions that allow full epidermal differentiation (i) the basement membrane protein BM-600/nicein, identified by the mAb GB3, is codistributed with laminin and collagen type IV as well as with the bullous pemphigoid antigen in footprints deposited by growing and migrating colonies; (ii) the integrin heterodimer alpha 6 beta 4 is codistributed with the same molecules suggesting its spatial association with basement membrane components; (iii) the distribution pattern of alpha 6 beta 4 and BM-600/nicein underneath individual cells is identical and is characterized by a typical "leopard skin" pattern complementary to the distribution of submembraneous F-actin microfilament network; (iv) a rabbit polyclonal antiserum to kalinin (R4012) used in double-label immunofluorescence staining with mAb GB3 shows that this protein has the same distribution as BM-600/nicein and this suggests that they are identically located; and (v) immunoprecipitation with mAb GB3 to BM-600/nicein and BM165 to kalinin shows identical bands suggesting that nicein and kalinin represent the same molecular entity. We suggest that alpha 6 beta 4 displays not only an adhesive role for keratinocytes in view of its reported association to hemidesmosomes but may also be involved in organizing the molecules of the epithelial extracellular matrix, including those forming the basement membrane zone and hemidesmosomes, a function proposed for other integrins in other cellular systems

The basement membrane protein BM-600/nicein codistributes with kalinin and the integrin alpha 6 beta 4 in human cultured keratinocytes.

The observation is reported that in low-passage human keratinocyte colonies cultured under conditions that allow full epidermal differentiation (i) the basement membrane protein BM-600/nicein, identified by the mAb GB3, is codistributed with laminin and collagen type IV as well as with the bullous pemphigoid antigen in footprints deposited by growing and migrating colonies; (ii) the integrin heterodimer alpha 6 beta 4 is codistributed with the same molecules suggesting its spatial association with basement membrane components; (iii) the distribution pattern of alpha 6 beta 4 and BM-600/nicein underneath individual cells is identical and is characterized by a typical 'leopard skin' pattern complementary to the distribution of submembraneous F-actin microfilament network; (iv) a rabbit polyclonal antiserum to kalinin (R4012) used in double-label immunofluorescence staining with mAb GB3 shows that this protein has the same distribution as BM-600/nicein and this suggests that they are identically located; and (v) immunoprecipitation with mAb GB3 to BM-600/nicein and BM165 to kalinin shows identical bands suggesting that nicein and kalinin represent the same molecular entity. We suggest that alpha 6 beta 4 displays not only an adhesive role for keratinocytes in view of its reported association to hemidesmosomes but may also be involved in organizing the molecules of the epithelial extracellular matrix, including those forming the basement membrane zone and hemidesmosomes, a function proposed for other integrins in other cellular systems