Matrix metalloproteinases (MMPs) play an important role in intestinal extracellular matrix homeostasis. An overexpression of MMPs results in tissue destruction and local inflammation and has been associated with multiple inflammatory diseases. These host proteases might also be important in tissue damage caused by infectious agents, such as in intestinal damage in Clostridium perfringens-induced avian necrotic enteritis (NE). The aim of the present study was to elucidate the effect of a C. perfringens infection on the MMP activity in the small intestine of birds with a pre-disposing coccidial infection to obtain a more thorough understanding of the pathogenesis of NE. For this purpose, the gelatinolytic activity present in jejunal tissue of Eimeria infected birds which were challenged with either a pathogenic C. perfringens type G strain or a commensal C. perfringens type A strain was analyzed using substrate zymography. The results show that infection of broilers with Eimeria and different C. perfringens strains, independent of their pathogenicity, decreases the expression of a 40–45 kDa host collagenase in the jejunum, as compared to the expression in Eimeria-infected control birds. It was also shown that the expression of 2 MMPs with molecular weights of approximately 50–60 and 60–70 kDa was significantly lower in necrotic tissue as compared to the activity in macroscopically healthy tissue adjacent to the lesion. These results indicate that host collagenases are not elicited by the C. perfringens infection for permeabilizing the host mucosa to allow penetration of the NetB toxin in Eimeria infected broilers.

Aging is accompanied by progressive functional decline and morphological defects of cholinergic neurons. Some probiotic bacteria with proficiency for biofilm formation in the gut are being discussed as potentially neuroprotective. Here, we screened Bacillus subtilis (B. subtilis) strains for biofilm production, using an in vitro assay. Thereafter, a transgenic Caenorhabditis elegans (C. elegans) strain with its cholinergic neurons expressing green fluorescent protein (GFP) was fed for up to 15 days on either the identified biofilm-producing B. subtilis strain B4U 50 or the control B. subtilis strain 168, with or without addition of a standardized Ginkgo biloba preparation. The morphology of the cholinergic neurons was monitored at several consecutive days by fluorescence microscopy. The occurrence of morphological defects such as knots and ruptures within the axons of cholinergic neurons, as observed with increasing age, was significantly lower in nematodes provided with the B4U 50 strain. Even worms whose diet was switched to B4U 50 later in life showed less damage of their neurons, as compared to worms fed on the control strain. Supplementation with the Ginkgo biloba preparation was neuroprotective in worms fed on either B. subtilis strain, while a stronger beneficial effect was observed upon combined administration of B. subtilis B4U 50 and the Ginkgo biloba preparation. In conclusion, feeding a B. subtilis strain proficient for biofilm formation, B4U 50, was neuroprotective when compared to a diet consisting of control B. subtilis, delaying the onset of aging-associated morphological defects in cholinergic neurons of C. elegans. Graphical Abstract