The influence of vitamin E on immune function and response to vaccination in older horses.

Horses have an increased susceptibility to infection because of a decline in immune function with advancing age. Vitamin E has been found to play a key role in normal immune system function. The purpose of the study was to examine the effect of vitamin E supplementation on immune function and response to vaccination in older horses. Predominantly older horses (18.9 +/- 1.3 yr, range 7 to 26 yr; 523 +/- 38 kg of BW) were supplemented orally once daily for 16 wk with either all-rac-alpha-tocopheryl acetate (15 IU/kg of BW; n = 8) or a placebo (n = 8). One horse from each group was removed from the study for reasons not related to the study. Serum alpha-tocopherol concentration, neutrophil and monocyte bacterial killing ability, lysozyme activity, immunoglobulin concentration (IgG(a), IgG(b), IgG(T), and IgM), and neutralizing antibody production to West Nile virus vaccination were determined. The overall serum alpha-tocopherol concentration of the vitamin E-supplemented horses was greater than that of placebo-supplemented horses (P < 0.001). Bacterial killing capacity of monocytes and neutrophils increased in the vitamin E-supplemented horses (P < 0.05). Vitamin E-supplemented horses had greater serum IgG(a) (P < 0.001) and IgG(T) (P = 0.003) concentrations but produced less serum IgG(b) (P = 0.023) than placebo-supplemented horses. There was no effect of vitamin E supplementation on IgM production. The neutralizing antibody response to vaccination against West Nile virus was unaffected by vitamin E supplementation. There was a continuous increase in serum lysozyme concentration in placebo-supplemented horses, whereas serum lysozyme concentration did not increase until wk 12 in vitamin E-supplemented horses. In conclusion, vitamin E supplementation of predominantly older horses differentially modulated general cell-mediated and humoral immune function. Further research is needed to fully understand the effect of vitamin E on the immune function of horses.

Protease activity in the plasma of American oysters, Crassostrea virginica, experimentally infected with the protozoan parasite Perkinsus marinus.

Perkinsus marinus is responsible for disease and mortality of the American oyster, Crassostrea virginica. To investigate the interactions between P. marinus and oyster hemocytes, protease activity was measured in plasma of oysters collected 4 hr, 24 hr, 4 days, and 2 mo after experimental infection with P. marinus. A significant increase in protease activity was observed in oyster plasma 4 hr after injection with P. marinus, followed by a sharp decrease within 24 hr. Gelatin-impregnated gel electrophoresis showed the presence of 2 major bands (60 and 112 kDa) and 3 less prevalent bands (35, 92, and 200 kDa) with metalloproteinaselike activity in the plasma of noninfected oysters. Additional bands in the 40- to 60-kDa range, corresponding to P. marinus serine proteases, were observed in oyster plasma at early time points after infection. A transient, but significant, decrease in the activity of oyster metalloproteinases was observed at early time points after infection. Coincubation of oyster plasma with P. marinus extracellular products resulted in a decrease in oyster metalloproteinases and several P. marinus proteases. This study provides insights into the role of proteases in the pathogenesis of Dermo disease.

Molecular cloning, sequencing and characterization of omp48, the gene encoding for an antigenic outer membrane protein from Aeromonas veronii.

AIMS: To clone, sequence and characterize the gene encoding the Omp48, a major outer membrane protein from Aeromonas veronii. METHODS AND RESULTS: A genomic library of Aer. veronii was constructed and screened to detect omp48 gene sequences, but no positive clones were identified, even under low stringency conditions. The cloned gene probably was toxic to the host Escherichia coli strain, so the cloning of omp48 was achieved by inverse PCR. The nucleotide sequence of omp48 consisted of an open reading frame of 1278 base pairs. The predicted primary protein is composed of 426 amino acids, with a 25-amino-acid signal peptide and common Ala-X-Ala cleavage site. The mature protein is composed of 401 amino acids with a molecular mass of 44,256 Da. CONCLUSIONS: The omp48 gene from Aer. veronii was cloned, sequenced and characterized in detail. BLAST analysis of Omp48 protein showed sequence similarity (over 50%) to the LamB porin family from other pathogenic Gram-negative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacterial diseases are a major economic problem for the fish farming industry. Outer membrane proteins are potentially important vaccine components. The characterization of omp48 gene will allow further investigation of the potential of Omp48 as recombinant or DNA vaccine component to prevent Aer. veronii and related species infections in reared fish.

Evaluation of eukaryotic promoters for the construction of DNA vaccines for aquaculture.

We evaluated fish promoters as an alternative to viral promoters in the construction of DNA vaccines for aquaculture. A carp beta-actin promoter drove expression of the luciferase gene in live fish tissue to levels comparable to the CMVtk promoter.

Isolation and Characterization of an Actin Promoter from the Red Abalone (Haliotis rufescens).

: We have isolated and characterized the 5'-flanking and part of the coding region of an actin gene from the red abalone Haliotis rufescens. There is high sequence homology between the abalone actin coding region and actins from other species. The sequence of this abalone actin is more closely related to vertebrate cytoplasmic actins than to muscle actins. RNase protection assays located the position of the transcription start point 66 bp upstream of the initiation codon. Promoter prediction by neural network located a TATA box 30 bp upstream of the transcription start point. A search with the SIGNAL SCAN program identified several potential transcription factor binding sites in the abalone sequence. These sites include sequences highly conserved in other actin promoters, like several putative CAAT and E boxes and a modified CArG box. Transfection assays with a construct containing the 5' flanking region of the abalone actin coupled to a luciferase reporter gene showed that the promoter is functional in mammalian and fish cell lines, as well as in abalone gonad tissue. Expression vectors constructed with the abalone actin promoter will be useful for gene transfer studies into abalone and other mollusks.

Infectious necrotizing enteritis and mortality caused by Vibrio carchariae in summer flounder Paralichthys dentatus during intensive culture.

An epizootic causing mortality among cultured summer flounder Paralichthys dentatus occurred in summer of 1998 at a land-based facility on Narragansett Bay, Rhode Island, USA. The disease, flounder infectious necrotizing enteritis (FINE), was characterized by reddening around the anal area, distended abdomens filled with opaque serosanguineous fluid, enteritis and necrosis of the posterior intestine. In extreme cases of the disease, the posterior intestine was detached from the anus and was observed coming out the vent. The intestine of individuals that recovered from the disease ended in a blind-sac; the abdomens of these fish were distended, due to food and water inside the intestinal blind-sac. A bacterium was isolated from ascites fluid and kidney of moribund flounder and identified as the causative agent in challenge experiments. The pathogen was identified as Vibrio carchariae by morphological and biochemical characteristics and sequence of the 16S rRNA. The LD50 estimate was 5 x 10(5) colony-forming units injected intraperitoneally into 100 to 200 g summer flounder.

Structural and functional differences in the promoter and 5' flanking region of Ldh-B within and between populations of the teleost Fundulus heteroclitus.

We have investigated the mechanisms underlying differences in the transcriptional regulation of lactate dehydrogenase-B (Ldh-B) between northern and southern populations of a teleost fish, Fundulus heteroclitus. A 1-kb region immediately 5' of the gene was sequenced from populations throughout the species range. There were two major allele classes in the sample, one containing alleles from Maine and another containing those from Florida. Populations from intermediate localities contained both allele classes. Some individuals from Georgia had sequences intermediate between the two classes, representing either ancestral alleles or recombinants. Tests of neutrality were applied to determine whether observed variation was consistent with neutral expectations. Significant deviations from neutral expectations were detected for the 5' flanking region, but not for other loci. The functional consequences of flanking sequence variation were assessed by transfection of reporter gene constructs into cultured cells and injection into living fish. Consistent with observed variation in Ldh-B transcription rate between populations, significant differences in reporter gene activity were driven by flanking regions from northern and southern populations both in cell culture and in vivo. This functional differentiation, coupled with departures from neutral expectations, suggests that selection may have acted on the regulation of Ldh-B in F. heteroclitus.

Glomerular up-regulation of EIIIA and V120 fibronectin isoforms in proliferative immune complex nephritis.

Fibronectin: (FNs) comprise a family of adhesive glycoproteins that are prominent components of mesangial extracellular matrix and accumulate during glomerular injury. By alternative splicing of an unique mRNA precursor, various FN isoforms can be originated. In rat, three regions of the molecule are involved: EIIIA, EIIIB and V. Because specific FN isoforms are expressed in embryogenesis and wound healing, conditions characterized by cell migration and adhesion, we examined the pattern of FN isoforms in the mild and severe phases of a progressive immune complex proliferative nephritis in rats. We constructed specific probes to analyze the splicing pattern of FN pre-mRNAs by ribonuclease protection assays. FN mRNAs containing EIIIA, EIIIB and V regions increased along, the progression of nephritis, though the increment of EIIIB-FN mRNA was modest. However, different regulation of all these isoforms was observed. The percentage of FN mRNA containing the EIIIA exon versus total FN increased with the severity of the disease, while the percentage of FN mRNA containing the EIIIB exon decreased. Relative V-FN mRNA expression versus total FN mRNA increased only in the severe phase. By means of specific antibodies we also studied the presence of EIIIA, EIIIB and V-FN proteins in the kidney. In the normal glomerutus, EIIIA-FN protein was barely detectable in the mesangium, increasing in the mild phase of nephritis. In the severe phase of nephritis, increased EIIIA-FN was localized in the mesangium, in Bowman's capsule and in crescents. By contrast, EIIIB-FN protein in the glomerulus was absent even in the severe phase. V120-FN protein, an isoform that mediates the attachment of leukocytes through the VLA-4 integrin, was present in the mesangium and glomerular capillary loops in control animals, and increased in the severe phase of nephritis, coinciding with a strong leukocyte infiltration. In conclusion, our results show that during immune glomerular injury there were marked changes in the pattern of FN isoforms expression. Since those isoforms, particularly V120 isoform, are important in cell adhesion and migration, their up-regulation may facilitate the recruitment of cells into the injured glomeruli. The blockade of the interaction between V120-FN and infiltrating leukocytes may represent a new approach to the treatment of nephritis.

Interferon-inducible protein-10 is highly expressed in rats with experimental nephrosis.

Interferon-inducible protein (IP)-10 is a small glycoprotein member of a family of chemotactic cytokines structurally related to interleukin-8. We have recently described the induction of IP-10 mRNA in mouse mesangial cells stimulated with lipopolysacharide, interferon-gamma, and tumor necrosis factor-alpha. To further evaluate a possible role for this chemokine in renal injury, we have studied IP-10 in an experimental model of nephrosis induced in rats by adriamycin. High levels of glomerular IP-10 mRNA expression and glomerular and tubulointerstitial IP-10 protein were seen on day 21, coinciding with maximal proteinuria, glomerular tumor necrosis factor mRNA expression, and interstitial cellular infiltrates. Maintenance on a low protein diet not only delayed the appearance of proteinuria and interstitial cellular infiltrate but also decreased glomerular IP-10 mRNA expression. Isolated normal glomeruli and cultured glomerular epithelial and mesangial cells from normal rats expressed IP-10 mRNA upon stimulation with 100 U/ml interferon or 1 microgram/ml lipopolysaccharide for 3 hours. IP-10 mRNA expression was also inducible by lipopolysaccharide and cytokines in NRK 49F renal interstitial fibroblasts and, to a lesser extent, in NRK 52E tubular epithelial cells. Furthermore, IP-10 protein was inducible in murine mesangial cells. We conclude that IP-10 is highly inducible in vitro and in vivo in resident glomerular and tubulointerstitial cells. IP-10 may participate in the modulation of renal damage in experimental nephrosis.

Fibronectin (FN) decreases glomerular lesions and synthesis of tumour necrosis factor-alpha (TNF-alpha), platelet-activating factor (PAF) and FN in proliferative glomerulonephritis.

We have studied the effect of therapy with plasma FN on glomerular synthesis of PAF, TNF-alpha and FN, in experimental proliferative glomerulonephritis. Glomerular PAF, TNF-alpha and FN production were increased in rats with nephritis. Peak glomerular PAF production preceded, while peak glomerular TNF-alpha bioactivity coincided with maximal proteinuria. Rats treated with FN (5 mg/kg per 48 h) for 15 days had less proteinuria, glomerular and interstitial cell infiltration and glomerular PAF, TNF-alpha and FN synthesis than non-treated rats. In order to characterize further the mechanisms of action of FN, healthy rats were injected with either FN or saline. Peripheral blood mononuclear cells and neutrophils from healthy rats injected with FN secreted less TNF-alpha and PAF, respectively, than those obtained from saline-treated rats. Our data suggest that the beneficial effect of FN may be related to decreased number of glomerular leucocytes and decreased synthesis of inflammatory mediators and extracellular matrix.

Involvement of tumor necrosis factor and platelet-activating factor in the pathogenesis of experimental nephrosis in rats.

BACKGROUND: The experimental nephrosis induced in rats by adriamycin (ADR) or puromycin aminonucleoside (PA) provide a useful model to study the participation of inflammatory mediators in the pathogenesis of proteinuria. EXPERIMENTAL DESIGN: We have measured tumor necrosis factor (TNF) and platelet-activating factor (PAF) production by glomeruli of rats with nephrosis, as well as the effect of treatment with the PAF antagonist, BN52021. We have also evaluated the in vitro effects of ADR, PA, and PAF on TNF and PAF production, cell viability, and protein synthesis in glomerular mesangial cells and glomerular epithelial cells (GEC) in culture. RESULTS: In ADR nephrosis, the greatest production of PAF was on day 14, preceding maximal proteinuria, whereas the highest levels of TNF where observed on day 21 after ADR injection, the moment at which proteinuria reached maximal levels. In PA nephrosis, glomerular PAF production peaked twice (days 1 and 15), before and after maximal proteinuria (day 11), whereas TNF production peaked from days 2 to 11, and slowly declined until day 21. In both models, treatment with BN52021 induced a striking decrease in proteinuria, as well as a diminution in glomerular TNF and PAF production. Both ADR and PA induced TNF and PAF production in whole glomeruli, glomerular mesangial cells, and GEC in culture. As shown by a 51Cr release assay, ADR and PA were toxic to GEC. This effect was inhibited by PAF antagonists and by anti-TNF antibodies. Whereas TNF was moderately toxic to GEC, PAF had no effect on 51Cr release. TNF toxicity was abolished by anti-TNF antibodies and largely diminished by PAF antagonists. CONCLUSIONS: TNF and PAF may participate in the induction of GEC damage and the development of proteinuria in two experimental models of nephrosis in rats.

The potential role of inflammatory and fibrogenic cytokines in the glomerular diseases.

In recent years increasing evidence has been accumulated on the role of cytokines in mediating glomerular and renal damage. Many such cytokines are released in the inflamed glomeruli by leukocytes and intrinsic glomerular cells. Cytokines not only recruit inflammatory cells into the injured glomeruli, but also induce a variety of responses on glomerular cells that range from a direct toxic effect to shape changes, proliferation, and induction of the release of inflammatory mediators and extracellular matrix, and could promote further glomerular damage. Moreover, exogenous administration of cytokines has induced glomerular injury in healthy animals and has enhanced renal damage in animals with glomerulonephritis. Anti-cytokine strategies have proved to be effective therapeutical alternatives in experimental models of glomerular diseases and may provide a more specific approach to the management of human glomerulonephritis.

Experimental IgA nephropathy secondary to hepatocellular injury induced by dietary deficiencies and heavy alcohol intake.

BACKGROUND: In humans, alcoholic liver disease is frequently associated with IgA mesangial deposits, microscopic hematuria and a small amount of proteinuria, identifying a secondary form of IgA nephropathy. Alcoholic liver disease is almost always associated with nutritional deficiencies. EXPERIMENTAL DESIGN: In order to examine the relationship between alcohol intake and/or inadequate diet and IgA nephropathy, groups of 4 week-old-male Lewis rats were maintained on a lipotrope-deficient (LD) diet (N = 20), intragastric infusions of a commercial whiskey (1.5 ml/100 gm body weight) three times a week, and regular chow (N = 23) or both intragastric whiskey infusion and an LD diet (N = 17). A fourth control group (N = 19) was given no whiskey and normal chow. RESULTS: All rats given the LD diet had marked steatosis and elevated "liver" enzymes. Changes were more severe, and with early bridging fibrosis and nodule formation in those also given whiskey, associated with increased hepatic content of mRNA encoding transforming growth factor-beta. A moderate steatosis without alteration in serum enzymes or transforming growth factor-beta expression was found in rats given whiskey (all p < 0.0001) compared with controls. IgA accumulated in hepatic sinusoids instead of in canaliculi and bile ducts, suggesting impaired transport of IgA and IgA immune complexes from blood to bile, in rats given an LD diet and/or whiskey infusion. A moderate increase in mesangial matrix was observed only in rats given both whiskey and an LD diet. Bright granular IgA and mild granular C3 mesangial deposits and electron-dense deposits were evident in 63 to 70% of experimental rats (all p < 0.001) versus only trace deposits in 5 to 11% of controls. Moderate IgG codeposits were present in 34 to 55% of rats given the LD diet and/or whiskey (all p < 0.02), versus trace deposits in 10% of controls. Significant hematuria and proteinuria were observed in rats given the LD diet and/or whiskey (p < 0.0001) versus controls. Intestinal permeability measured by xylose absorption was significantly increased relative to controls only in rats given both whiskey and the LD diet (p < 0.001). Serum IgA specific for selected alimentary antigens was increased relative to controls in 75 to 100% of the experimental rats. CONCLUSIONS: The combination of LD diet and alcohol intake, which mimics the human alcoholic condition, promotes hepatic and renal changes, leading to hepatocellular injury and a secondary form of IgA nephropathy.

Expression of IP-10, a lipopolysaccharide- and interferon-gamma-inducible protein, in murine mesangial cells in culture.

IP-10 is an early gene induced in multiple cell types by a variety of proinflammatory agents, notably interferons (IFNs) and lipopolysaccharide (LPS). To determine whether this protein might play a role in amplifying immune-mediated glomerular injury, we cultured mouse mesangial cells with several stimuli for various times. Increasing amounts of IFN-gamma (to 100 units/ml) elicited increasing levels of IP-10 messenger RNA (mRNA), sustained to 24 hours, but had no effect on tumor necrosis factor-alpha (TNF-alpha) mRNA. LPS induced transient IP-10 mRNA expression that peaked at 8 hours; TNF-alpha mRNA was also increased. TNF-alpha at doses up to 10 ng/ml and soluble immune complexes up to 150 micrograms/ml antibody evoked 3- to 5-fold increases in IP-10 mRNA expression, much less than the 30- to 70-fold increases seen with IFN-gamma and LPS. We conclude that IFN-gamma, LPS, and other agonists can amplify glomerular immune injury, perhaps via elevated expression of IP-10.

The role of platelet-activating factor (PAF) in experimental glomerular injury.

Platelet-activating factor (PAF) is a potent autacoid that participates in inflammation and other pathophysiological processes. In this review we deal with recent evidence suggesting that PAF is a mediator that is released early during glomerular injury. PAF can be synthesized in the glomerulus by infiltrating intrinsic glomerular cells. Normal glomeruli produce PAF upon stimulation, and glomerular PAF synthesis is increased in a variety of experimental glomerulopathies. The local infusion of PAF into the renal artery of isolated blood-free kidneys induces proteinuria. PAF attracts and activates inflammatory cells. Glomerular mesangial, endothelial and epithelial cells are also targets for PAF. Therapy with specific PAF receptor antagonists has prevented or reduced proteinuria and improved glomerular inflammation in several experimental models of proliferative glomerulonephritis and minimal change nephrosis. However, the beneficial effect of administration of PAF antagonists once proteinuria is fully developed has been minimal. PAF may also play a role in the recruitment of inflammatory interstitial cells.

Involvement of lipid mediators in the pathogenesis of experimental nephrosis in rats: its pharmacological modulation.

The administration of a single-injection of Adriamycin (ADR) to rats results in marked proteinuria and glomerular morphological changes that are similar to minimal change disease in humans. We have hypothesized that Adriamycin, by itself or through the release of some mediators from resident glomerular cells, could provoke a damage to epithelial glomerular cells. Sprague-Dawley rats received a single injection of Adriamycin, 7.5 mg/kg bw, allocated randomly in several groups and treated throughout 2 weeks of follow-up. All control nontreated animals developed important nephrotic syndrome and degenerative lesions of epithelial glomerular cells. Isolated glomeruli from animals injected with adriamycin 14 days before synthesized thromboxane (TxB2) and platelet activating factor (PAF) in amounts above the rates of control glomeruli. Animals treated with three structurally different PAF receptor antagonists did not present proteinuria or only to a very low extent (p less than 0.0005). In these rats no alterations in epithelial cells were noted. Furthermore, no significant changes in the TxB2 production were noted in rats treated with BN 52021, a PAF receptor antagonist. Leukotrienes also seem to participate since treatment with a 5-lipoxygenase inhibitor partially corrected proteinuria. Moreover, glomeruli from animals with nephrosis and treated with this compound presented only a discrete reduction in the PAF synthesis. On the whole, these data suggest a key role for PAF in the pathogenesis of adriamycin nephropathy. Other lipid meditors, released in cascade simultaneously or thereafter, could perpetuate the renal damage.

Evidence suggesting a role for platelet-activating factor (PAF) in experimental nephrotic syndrome.

Sprague-Dawley rats injected with a single dose of adriamycin at 7.5 mg/kg/day developed an important and persistent proteinuria from day 14. Animals treated from day 0 to 3 weeks with PAF-receptor antagonists (BN 52021 or alprazolam) did not present (p less than 0.0005) the adriamycin-induced proteinuria or only to a very low extent. Furthermore, epithelial glomerular cells presented in these animals a normal aspect, while in rats injected with adriamycin, but not treated, the epithelial cells showed effacement of foot processes and intensive degenerative changes. By contrast, rats treated with steroids or cyclosporin did not present a significant reduction in proteinuria or improvements in epithelial cell lesions. Rats injected with adriamycin also presented an increase in the number of inflammatory infiltrating cells, chiefly la(+)-reactive cells (OX6+ cells), macrophages (ED1+ cells) and T-cytotoxic/suppressor cells (OX8+ cells). Concomitant administration of PAF-receptor antagonists induced a significant reduction in the number of these cells. Glomerular cells from normal control rats incubated with adriamycin incorporated 3H-acetate into a polar lipid with biological and migratory characteristics on thin-layer chromatography similar to synthetic PAF. On the whole, our data suggest a role for PAF in the pathogenesis of experimental nephrotic syndrome induced by adriamycin.