P. E. Van den Steen

Inhibition of Enzymatic Degradation of Adhesive-Dentin Interfaces

Adhesive procedures activate dentin-associated matrix metalloproteinases (MMPs), and so iatrogenically initiate bond degradation. We hypothesized that adding MMP inhibitors to adhesive primers may prevent this endogenous enzymatic degradation, thereby improving bond durability. A non-specific MMP inhibitor (chlorhexidine) and a MMP-2/9-specific inhibitor (SB-3CT) were admixed to the primers of an etch & rinse and a self-etch adhesive, both considered as gold-standard adhesives within their respective categories. For dentin powder exposed to the adhesives under clinical application conditions, gelatin zymography revealed the release of MMP-2 (not of MMP-9) by the etch & rinse adhesive, while no release of enzymes could be detected for the mild self-etch adhesive, most likely because of its limited dentin demineralization effect. The built-in MMP inhibitors appeared effective in reducing bond degradation only for the etch & rinse adhesive, and not for the self-etch adhesive. Water sorption of adhesive interfaces most likely remains the principal mechanism of bond degradation, while endogenous enzymes appear to contribute to bond degradation of only etch & rinse adhesives.

Matrix metalloproteinase-9/gelatinase B is a putative therapeutic target of chronic obstructive pulmonary disease and multiple sclerosis

Matrix metalloproteinases (MMPs) are a large family of proteolytic enzymes involved in an array of physiological and pathological processes from development, morphogenesis, reproduction, wound healing, and aging to inflammation, angiogenesis, neurological disorders, and cancer cell invasion and metastasis. The imbalance between MMP activity and the inhibitory action of tissue inhibitors of metalloproteinases (TIMPs) are implicated in multiple diseases. Secreted in the body in a latent form, upon activation MMP-9 (gelatinase B) acts on many inflammatory substrates, and thus is suspected of contributing to the progression of cardiovascular disease, rheumatoid arthritis, and the subjects of this review, chronic obstructive pulmonary disease (COPD) and multiple sclerosis (MS). COPD is the fourth most common cause of death in the United States. In COPD, increased expression of MMP-9 by inflammatory cells e.g. neutrophils and macrophages is correlated with a variety of processes that cause lung damage. MMP-9 is also important in cytokine and protease modulation; it degrades the serine protease inhibitor alpha(1)-antitrypsin, which thus may lead to lung destruction. MS affects approximately 400,000 Americans and over a million people worldwide. Upregulation of MMP-9 increases the permeability of the blood brain barrier (BBB), facilitates the infiltration of leukocytes into the central nervous system, and causes myelin sheath degradation and neuronal damage. Early stage clinical trials have shown promising results when MMP-9 is inhibited in MS. These observations lead to the hypothesis that MMP-9 is a potential drug target for both COPD and MS and further development of highly potent and specific MMP-9 inhibitors is warranted.

Ajuga remota Benth.: from ethnopharmacology to phytomedical perspective in the treatment of malaria.

Treatment and control of malaria have become more difficult with the spread of drug-resistant parasites and insecticide-resistant mosquito vectors. In the search for new antimalarial drugs, ethnopharmacological sources should merit more attention. Establishing the safety of traditional herbal medicines, along with identifying their active principles, are essential steps in the production of a properly standardized and accessible herbal medicine. Phytochemical characterization could also serve as a base for the development of new chemical compounds. The genus of Ajuga belongs to the family Lamiaceae and contains at least 301 species. Many of these plants have been used in traditional medicine. Ajuga remota in particular is traditionally used as a herbal remedy for fever and infections, and is prescribed for malaria by 66% of the Kenyan herbalists. A large number of compounds have already been isolated from A. remota, including ergosterol-5,8-endoperoxide (6), ajugarin-I (1), 8-O-acetylharpagide (5) and several phytoecdysteroids. In vitro pharmacological studies have been conducted on constituents of A. remota of which some of them displayed a concentration-dependent inhibition of chloroquine-sensitive and -resistant Plasmodium falciparum and Mycobacterium tuberculosis. Inhibition of parasitaemia was demonstrated in mouse models with P. berghei, supporting the traditional use of the plant against malaria. In this state-of-the-art review, A. remota as a possible therapeutic tool for malaria is discussed.

ASSOCIATION OF IMMUNE CELLS WITH NEUROEPITHELIAL BODIES IN THE LUNGS OF NEONATAL DOGS, CATS AND HAMSTERS

A close topographical association between neuroepithelial bodies and immune cells is occasionally observed in the lungs of various neonatal mammalian species. The immune cells concerned are mast cells and neutrophil or eosinophil granulocytes. In the lungs of newborn puppies having undergone left lung autotransplantation, mast cells are particularly numerous in the airway mucosa of both right and left lungs and their association with neuroepithelial bodies is highly significant. Several of the substances known to be synthesized by the neuroepithelial bodies have a chemoattractive effect on immune cells. Thus, our observations indicate that intrapulmonary neuroepithelial bodies contribute to the local immune response.

Gelatinase B Participates in Collagen II Degradation and Releases Glycosylated Remnant Epitopes in Rheumatoid Arthritis

Rheumatoid arthritis is an autoimmune disease characterized by chronic inflammation of the joints. It is associated with the activation of autoreactive T-cells and with production of autoantibodies. The main auto-antigen is collagen type II, which is a major constituent of the cartilage in the joint. The inflammation causes cartilage degradation, hyperplasia of synovial membranes, accumulation of excessive synovial fluid, and, in the worst cases, bone erosion. The exact aetiology is not known, but it is clear that inflammatory reactions and auto-antibodies, which activate the complement cascade, are main causes of the cartilage degradation. Inhibition of inflammation by interference with some of the main pro-inflammatory cytokines, interleukin-1 (IL-1) and tumor necrosis factor-a (TNF-a) has proven to be beneficial and constitutes the basis of currently approved treatments. Matrix metalloproteinases are a family of neutral Zn2+-dependent endoproteases, which share a number of homologous domains (Nagase and Woessner, 1999). These domains are the Zn2+-containing active site, kept inactive by a propeptide in the pro-enzyme form, and a hemopexin domain (Fig. 1). The latter domain is present in most MMPs except for matrilysins (MMP-7 and -26) and cysteine-array MMP (CA-MMP or MMP-23). Several MMPs contain additional domains, such as a carboxyterminal membrane anchor in membrane-type MMPs (MT-MMPs), a fibronectin-like domain in gelatinases A and B (MMP-2 and -9), and a unique mucin-type domain in gelatinase B. The latter domain is often named collagen type

11β-hydroxysteroid dehydrogenase type 1 has no effect on survival during experimental malaria but affects parasitemia in a parasite strain-specific manner

Malaria is a global disease associated with considerable mortality and morbidity. An appropriately balanced immune response is crucial in determining the outcome of malarial infection. The glucocorticoid (GC) metabolising enzyme, 11β-hydroxysteroid dehydrogenase-1 (11β-HSD1) converts intrinsically inert GCs into active GCs. 11β-HSD1 shapes endogenous GC action and is immunomodulatory. We investigated the role of 11β-HSD1 in two mouse models of malaria. 11β-HSD1 deficiency did not affect survival after malaria infection, but it increased disease severity and parasitemia in mice infected with Plasmodium chabaudi AS. In contrast, 11β-HSD1 deficiency rather decreased parasitemia in mice infected with the reticulocyte-restricted parasite Plasmodium berghei NK65 1556Cl1. Malaria-induced antibody production and pathology were unaltered by 11β-HSD1 deficiency though plasma levels of IL-4, IL-6 and TNF-α were slightly affected by 11β-HSD1 deficiency, dependent on the infecting parasite. These data suggest that 11β-HSD1 is not crucial for survival of experimental malaria, but alters its progression in a parasite strain-specific manner.

Presence and Possible Implications of Open-Ring Centrioles, Multiple Basal Centrioles and Basal Cilia in Neonatal Hamster Bronchioles

In studying epithelio-stromal interactions in the neonatal hamster lung, basal centrioles, basal cilia and open-ring centrioles attracted our attention. The same structures are also found in bronchiolar epithelium of a 3-week-old fawn-hooded rat, indicating that they are not specific phenomena of hamster lung. Although cells with basal centrioles are not common, they are more readily observed in a sample of bronchioles at the second postnatal week as compared to the fourth neonatal day. The centrioles may often possess two satellites and function as microtubule organizing centers (MTOC). Open-ring centrioles are mature structures and also serve as MTOC. Apparently, triplets may de novo be added to and/or degraded from an open-ring centriole. The basal cilia and the cilia in the ciliated vacuoles/cysts, have a normal axonemal structure and may have a common origin from the basal centrioles. It is, however, unclear whether or not they are primary-like cilia. In addition, presence of the multiple basal MTOC and some morphologic features point to a high microtubule-associated vesicular transport activity and probably indicate an elevated interaction with the interstitium; thus, the cells have a different polarization then normal ciliated cells.

Epithelio-Stromal Interactions in Neonatal Hamster Bronchioles: Morphology and Distribution of Epithelial Foot Processes and Their Possible Relation to Epithelial Growth Inhibition

Morphology and distribution of epithelial foot processes (FP) were studied in hamster neonatal lung bronchioles. To correlate them with growth, bronchiolar mitotic index was determined, rat small intestine used as a reference tissue and the distribution of foot processes compared to the distribution of immunoreactivity against proliferating cell nuclear antigen (PCNA). In bronchioles, where growth occurs through dispersed mitoses, FP also occur dispersed throughout the whole perimeter of the epithelium; whereas in small intestine, where growth is localised in a specific region (crypts), FP are likewise confined to a distinct, but different, zone (villi). Staining the bronchioles for PCNA labels dispersed grouplets of nuclei; most of which being only weakly stained. In the intestines, strong immunostaining mainly occurs in the crypts, while the villi mainly display a weak nuclear stain. Additionally, in both types of tissue the distribution of FP and weak PCNA staining are parallel. Thus, an apparent association between FP, lack of proliferation and nucleoplasmic PCNA staining arises; the basis of which being presently unclear. However, a possible interrelating factor might be a growth inhibitory influence of epithelio-stromal interactions on the epithelial cells.