Basement membrane zone

Innate immune response profiles in pigs injected with vaccine adjuvants polydi(sodium carboxylatoethylphenoxy)phosphazene (PCEP) and Emulsigen

Vaccines are formulated with adjuvants to enhance or direct antigen-specific immune responses against pathogens. However, the mechanisms of action (MOA) of adjuvants are not well understood and are under-investigated in large animal species. We have previously reported that injection of mice induced innate immune responses as indicated by increased cell recruitment and cytokine production at the site of injection with polyphosphazene (PCEP) adjuvant. In the present study, we evaluated whether PCEP induced similar innate immune responses in pigs. Piglets were injected with either PCEP or Emulsigen intradermally (I.D.) and the local cellular infiltration and cytokine production were evaluated at the site of injection and the draining lymph nodes. PCEP induced infiltration of macrophages, T and B cells, leucocytes and necrotic debris at the site of injection as well as PCEP-induced leucocyte infiltration in the draining lymph nodes. Emulsigen induced diffuse infiltration of leucocytes, macrophages, and lymphocytes at the site of injection as well as at the draining lymph nodes. PCEP induced significant production of interleukin IL-1β, and IL-13 at the site of injection and IL-1β, and IL-6 at the draining lymph nodes. Emulsigen promoted the production of IL-1β, IL-6, and IL-12 at the site of injection but not in the draining lymph nodes. No cytokines were detected in blood after injection of either adjuvant. Together, our data indicate that in pigs, the adjuvants PCEP and Emulsigen stimulate early innate immune responses at the injection site by creating an immunocompetent environment that may contribute to increased immunogenicity of the co-administered antigens.

The glomerular basement membrane as a model system to study the bioactivity of heparan sulfate glycosaminoglycans

The glomerular basement membrane and its associated cells are critical elements in the renal ultrafiltration process. Traditionally the anionic charge associated with several carbohydrate moieties in the glomerular basement membrane are thought to form a charge selective barrier that restricts the transmembrane flux of anionic proteins across the glomerular basement membrane into the urinary space. The charge selective function, along with the size selective component of the basement membrane, serves to limit the efflux of plasma proteins from the capillary lumen. Heparan sulfate glycosaminoglycans are anionically charged carbohydrate structures attached to proteoglycan core proteins and have a role in establishing the charge selective function of the glomerular basement membrane. Although there are a large number of studies in the literature that support this concept, the results of several recent studies using molecular genetic approaches to minimize the anionic charge of the glomerular basement membrane would suggest that the role of heparan sulfate glycosaminoglycans in the glomerular capillary wall are still not yet entirely resolved, suggesting that this research area still requires new and novel exploration.

The electrical resistance breakdown assay determines the role of proteinases in tumor cell invasion

The electrical resistance breakdown of the Madin-Darby canine kidney (MDCK) cell monolayer provides a continuous assay system for cancer invasion that detects functional changes before morphological alterations. In this study, we address the question of whether physical contact between tumor cell and epithelial monolayer is a prerequisite for tumor cell invasion. When human melanoma cells were seeded directly (i.e., physical contact) on top of an electrically tight epithelial cell layer (5,800 +/- 106 Omega x cm2), electrical monolayer leakage led to an 18 +/- 3% reduction of transepithelial electrical resistance within 24 h. However, when melanoma cells were seeded close to the basolateral surface of the epithelial cell monolayer but separated by a filter membrane (i.e., no physical contact), electrical leakage occurred even more quickly (42 +/- 3% reduction in 24 h). Atomic force microscopy detected discrete structural changes between cells. Electrical leakage was effectively blocked by alpha2-macroglobulin or ilomastat, inhibitors of matrix metalloproteinases. We conclude that exocytosis of soluble proteases causes electrical breakdown of the MDCK monolayer, independently of physical contact between tumor cells and the monolayer.

Serum markers of lamellar basement membrane degradation and lamellar histopathological changes in horses affected with laminitis

In order better to evaluate the extent to which degradation of the lamellar basement membrane (LBM) by matrix metalloproteinases (MMP) occurs in equine laminitis, we determined the concentration of type IV collagen and laminin in normal and laminitic horses, using specific immunoassays. Blood samples were obtained from both the jugular and the cephalic veins of horses (n = 10) before and after the induction of acute alimentary laminitis by carbohydrate overload. Jugular and cephalic venous blood samples were also obtained from horses affected with naturally occurring laminitis (n = 16) and nonlaminitic controls (n = 8). The serum collagen IV concentration was not changed following the induction of laminitis in the experimental group. Serum collagen IV concentration was increased in jugular venous blood obtained from cases of naturally occurring laminitis (mean +/- s.e. 218.04 +/- 18.59 ng/ml) compared with nonlaminitic controls (157.50 +/- 10.93 ng/ml) (P<0.05). Serum collagen IV concentration was also increased in jugular venous blood obtained from severely laminitic horses (219.50 +/- 18.18 ng/ml) compared with nonlaminitic controls (157.50 +/- 10.93 ng/ml) (P<0.05). A difference in serum concentration of collagen IV was not identified based on chronicity of naturally occurring laminitis. Serum laminin concentration did not differ between laminitic and nonlaminitic horses. Differences in serum laminin concentration were not identified based on sampling location (jugular or cephalic vein), severity of laminitic pain, or chronicity of spontaneous laminitis. In conclusion, the circulating concentration of collagen IV was increased in horses affected with naturally occurring laminitis. The potential role for serum collagen IV assay for characterisation of equine laminitis warrants further investigation.

Tumor microvessels in melanoma express the beta-2 chain of laminin. Implications for melanoma metastasis

The ultrastructural localization of an amorphous matrix to the interface between microvessel endothelium and tumor cells has been recently reported in a series of melanomas. Laminin expression as documented by immunohistochemistry was localized to microvessels in melanomas showing the amorphous matrix. In order to identify more precisely the type of laminin present in this amorphous material, immunostaining was carried out on cryostat sections from 16 human melanoma specimens. Four murine monoclonal antibodies directed against the alpha-3, beta-2, beta-3 and gamma-2 laminin chains were employed. In the melanomas studied, alpha3, beta3 and gamma2 laminin chains showed only minimal focal vascular positivity. In contrast, the beta2 (16/16 cases) laminin chain exhibited a consistent positivity in an angiocentric pattern about tumor microvessels. In all melanomas, some tumor cells seemed to spread along the abluminal surface of the small vessels, exhibiting a pericytic location, particularly along the intratumoral projections formed by the beta2 laminin chain. Given the role of laminin in migration and tumor progression, the results suggest a role of the beta2 laminin chain in melanoma spread, promoting tumor migration along the abluminal surface of vessel, a phenomenon which has been termed extra-vascular migratory metastasis.