5-LOX expression in the brain tissue from striped dolphins (Stenella coeruleoalba) stranded along the Italian coastline and affected, or not, by infectious encephalitis/meningo-encephalitis

Dolphin Morbillivirus (DMV) is regarded, along with Toxoplasma gondii and Brucella ceti, as a neurotropic pathogen of concern for free-ranging dolphins, with special reference to striped dolphins (Stenella coeruleoalba), a pelagic odontocete species which is very common in the Mediterranean Sea. Although a more or less severe encephalitis, or meningo-encephalitis, is known to occur in striped dolphins infected by the three aforementioned agents, very little information is available on the neuropathogenesis of such brain lesions, including the cell types (both neuronal and non-neuronal) involved in the course of infection and the molecular mechanisms leading to neurodegeneration.Against this background, we aimed at characterizing the immunochemical (Western blot, WB) and the immunohistochemical (IHC) expression of a key-enzyme for mammalian infections (i.e., 5-lipoxygenase, 5-LOX) within the cerebral parenchyma from 8 striped dolphins, 2 of which had no morphologic evidence of central neuropathies, while the remaining 6 animals showed encephalitic or meningo-encephalitic lesions of various degree, associated either with DMV (1 dolphin), T. gondii (4 dolphins), or B. ceti (1 dolphin) infection. The software ImageJ was used for densitometry imaging to analyze the intensity of WB bands.All the 6 animals affected by encephalitis/meningo-encephalitis showed an intensity of 5-LOX WB bands which was more pronounced than that observed in the two dolphins without any morphologic evidence of brain lesions, with the most prominent band intensity being detected in the B. ceti-infected animal. While the IHC characterization of the 5-LOX expression profiles in the brain parenchyma from the 8 dolphins is still underway, we believe that the finding related to a higher expression of this enzyme in the 6 animals affected by infectious encephalitis/meningo-encephalitis is of interest. Indeed, 5-LOX is considered to be a putative neurodegeneration biomarker both in human patients and in experimental animal models. Further investigation on this challenging issue is warranted. [...]