Immunohistochemical investigations on Brucella ceti-infected, neurobrucellosis-affected striped dolphins (Stenella coeruleoalba)

Bacteria of the genus Brucella cause brucellosis, an infectious disease common to humans as well as to terrestrial and aquatic mammals. Since 1994 several cases of Brucella spp. infection have been reported in marine mammals worldwide. While sero-epidemiological data suggest that Brucella spp. infection is widespread globally, detecting Brucella spp.-associated antigens by immunohistochemistry (IHC) in tissues from infected animals is often troublesome. The present study was aimed at investigating, by means of IHC based upon the utilization of an anti-Brucella LPS monoclonal antibody (MAb), the central nervous system (CNS) immunoreactivity shown by B. ceti-infected, neurobrucellosis-affected striped dolphins. The aforementioned MAb, previously characterized by means of ELISA and Western Blotting techniques, was able to immunohistochemically detect smooth brucellae both within the CNS from B. ceti-infected striped dolphins and within a range of tissues from Brucella spp.-infected domestic ruminants. In conclusion, the results of the present study are of relevance both from the B. ceti infection's diagnostic and pathogenetic standpoints.

N-3 PUFAs reduce oxidative stress in ESRD patients on maintenance HD by inhibiting 5-lipoxygenase activity

Reactive oxygen species formation and release of pro-inflammatory/pro-atherogenic cytokines, that is, interleukin 1-beta and tumor necrosis factor-alpha, need the activation of the arachidonic acid cascade via the enzyme 5-lipoxygenase (5-Lox). 5-Lox activity and expression are significantly increased in peripheral blood mononuclear cells (PBMCs) of end-stage renal disease (ESRD) patients on maintenance hemodialysis (HD). Diets enriched with n-3 polyunsaturated fatty acids (PUFAs) (omega-3) have been associated to a lower incidence of coronary heart disease (CHD) and a reduction in atherosclerotic lesions. Omega-3 may interfere with the arachidonic acid cascade by inhibiting 5-Lox. Lipid peroxidation, leukotriene B(4) (LTB(4)) production, 5-Lox activity and expression were investigated in PBMC isolated from ESRD patients under maintenance HD before and after a 3-month oral supplementation with omega-3 at a daily dose of 2700 mg of n-3 PUFAs at the average eicosapentaenoic acid/docosaesaenoic acid ratio of 1.2 and finally after a further 3-month washout with no omega-3 supplementation. PBMCs from non-uremic volunteers were also investigated for comparison to normal parameters. Administration of omega-3 reduced significantly lipid peroxidation (P < 0.0001), LTB(4) synthesis (P < 0.0001) and 5-Lox activity (P < 0.0001), with no effect on 5-Lox protein expression. After the 3-month washout, all parameters were comparable to those observed before treatment. Our results resemble those obtained after oral administration of vitamin E and are consistent with a reversible, dose-dependent inhibition of 5-Lox by omega-3. Upregulation of 5-Lox may also be related to the increased mitochondrial damage and apoptosis of PBMCs observed in ESRD patients compared to non-uremic controls. Omega-3 may thus protect PBMCs of ESRD patients against oxidative stress.