Chris Andry

Resolvin E1 Regulates Inflammation at the Cellular and Tissue Level and Restores Tissue Homeostasis In Vivo

Resolvin E1 (RvE1) is a potent proresolving mediator of inflammation derived from omega-3 eicosapentaenoic acid that acts locally to stop leukocyte recruitment and promote resolution. RvE1 displays potent counter-regulatory and tissue-protective actions in vitro and in vivo. Periodontal disease is a local inflammatory disease initiated by bacteria characterized by neutrophil-mediated tissue injury followed by development of a chronic immune lesion. In this study, we report the treatment of established periodontitis using RvE1 as a monotherapy in rabbits compared with structurally related lipids PGE2 and leukotriene B4. PGE2 and leukotriene B4 each enhanced development of periodontitis and worsened the severity of disease. Promotion of resolution of inflammation as a therapeutic target with RvE1 resulted in complete restoration of the local lesion, and reduction in the systemic inflammatory markers C-reactive protein and IL-1β. This report is the first to show that resolution of inflammation by a naturally occurring endogenous lipid mediator results in complete regeneration of pathologically lost tissues, including bone.

Rapamycin Ameliorates Proteinuria-Associated Tubulointerstitial Inflammation and Fibrosis in Experimental Membranous Nephropathy

Proteinuria is a risk factor for progression of chronic renal failure. A model of proteinuria-associated tubulointerstitial injury was developed and was used to examine the therapeutic effect of rapamycin. Two studies were performed. In study A, proteinuric rats were given sheep anti-Fx1A to induce experimental membranous nephropathy; control rats received normal sheep serum. Four weeks later, groups were subdivided and underwent laparotomy alone (two kidneys), nephrectomy alone (one kidney), or nephrectomy with polectomy (0.6 kidney). Renal function and morphology were evaluated 4 wk later. Whereas control rats never developed proteinuria, anti-Fx1A induced severe proteinuria. Proteinuria was unaffected by renal mass reduction. Proteinuric rats developed tubulointerstitial disease that was most severe in rats with 0.6 kidneys. Renal function (GFR) was reduced by loss of renal mass and was reduced further in proteinuric rats with 0.6 kidneys. In study B, the effect of rapamycin on the expression of candidate proinflammatory and profibrotic genes and the progression of proteinuria-associated renal disease were examined. All rats received an injection of anti-Fx1A and were nephrectomized and then divided into groups to receive rapamycin or vehicle. Gene expression, renal morphology, and GFR were evaluated after 4, 8, and 12 wk. Rapamycin reduced expression of the proinflammatory and profibrotic genes (monocyte chemotactic protein-1, vascular endothelial growth factor, PDGF, TGF-beta(1), and type 1 collagen). Tubulointerstitial inflammation and progression of interstitial fibrosis that were present in vehicle-treated rats were ameliorated by rapamycin. Rapamycin also completely inhibited compensatory renal hypertrophy. In summary, rapamycin ameliorates the tubulointerstitial disease associated with chronic proteinuria and loss of renal mass.

Postmortem whole-body magnetic resonance imaging as an adjunct to autopsy: Preliminary clinical experience

The purpose of this study was to evaluate whole‐body magnetic resonance imaging (MRI) of cadavers as an adjunct to autopsy. Eight consecutive patients underwent both whole‐body MRI and autopsy [either conventional (six), limited (one), or percutaneous (one)] within 24 hours of death. Comparison was made of major and minor abnormalities and predicted cause of death recorded by independent readers at both MRI and autopsy. Major discrepancies between the recorded primary cause of death at imaging and autopsy occurred in five (5) patients. These included a myocardial infarction found at autopsy alone, bowel infarction and portal venous gas found at MRI alone, and aortic dissection and occipital infarct found at MRI alone in a patient on whom only limited autopsy was performed. Postmortem MRI may represent a useful adjunct to autopsy, particularly in patients in whom autopsy is limited due to patient/family consent, inoculation risks, and ethnic doctrines. J. Magn. Reson. Imaging 2001;13:277–287.

Relationship Between Cavernosal Ischemia and Corporal Veno-Occlusive Dysfunction in an Animal Model

PURPOSE It has been postulated that cavernosal tissue ischemia secondary to arterial occlusive disease is associated with corporal veno-occlusive dysfunction. The goal was to correlate, for the first time, direct local intracavernosal blood flow measurements as a measure of cavernosal tissue perfusion with the integrity of corporal veno-occlusion in an animal model of vasculogenic impotence. MATERIALS AND METHODS The New Zealand White rabbit model of vasculogenic impotence was utilized (7 control, 9 atherosclerotic). After 16 weeks, intracavernosal blood flow was recorded directly by laser Doppler flowmetry. The relationships among peak intracavernosal blood flow, equilibrium intracavernosal pressure and corporal veno-occlusive function (as determined by intracavernosal pressure decay) were examined. RESULTS Significant differences in the atherosclerotic compared to control animals were noted in iliac artery blood flow (12 +/- 4 vs 31 +/- 7 ml./min.), peak intracavernosal blood flow during erection (16 +/- 7 vs 25 +/- 4 ml./min./100 gm. tissue), equilibrium intracavernosal pressure (48 +/- 11 vs 72 +/- 6 mm. Hg) and intracavernosal pressure decay (57 +/- 17 vs 36 +/- 8 mm. Hg). Peak intracavernosal blood flow during erection was found significantly related to both equilibrium pressure (r = 0.75) and cavernosal pressure decay (r = -0.8). CONCLUSIONS Abnormal intracavernosal blood flow (cavernosal ischemia) secondary to arterial occlusive disease predicts abnormal veno-occlusive function and poor erection quality.

NF-κB Activation Precedes Increases in mRNA Encoding Neurokinin-1 Receptor, Proinflammatory Cytokines, and Adhesion Molecules in Dextran Sulfate Sodium–Induced Colitis in Rats

Nuclear factor kappa B (NF-κ B) plays a key role in initiating inflammation associated with colitis. A systematic study was conducted in the rat DSS colitis model to determine the temporal relationship between NF-κ B activation and expression of substance P (SP), neurokinin-1 receptor (NK-1R), proinflammatory cytokines, and adhesion molecules. Rats were given 5% DSS in their water and sacrificed daily for 6 days. Colon tissue was collected for assessment of histological changes, NF-κ B activation, myeloperoxidase (MPO) activity, and expression of NK-1R, SP, TNFα, IL-1β, VCAM-1, ICAM-1, E-selectin, CINC-1, MIP-1α, and iNOS. NF-κ B activation increased, biphasically, on Day 1 and again on Days 4–6. The mRNA levels for ICAM-1, CINC-1, IL-1β, TNFα, VCAM-1, and NK-1R rose significantly (P< 0.05) by 2–4 days. Increased iNOS mRNA levels, MPO activity, and mucosal damage occurred on Day 6. These data demonstrate that NF-κ B activation substantially precedes the onset of physical disease signs and active inflammation.

Rapamycin delays but does not prevent recovery from acute renal failure: role of acquired tubular resistance.

Background. We reported that rapamycin impairs recovery after acute renal failure (ARF) in rats. The objective of this study was to determine if recovery will eventually occur after ARF despite continued rapamycin treatment. Methods. ARF was induced in rats by renal artery occlusion. Glomerular filtration rate (GFR), morphology, and tubular cell proliferation were assessed either 2, 4, 6, or 7 days later. Rats were treated daily with rapamycin or vehicle throughout the study. Cultured mouse proximal tubular (MPT) cells were used to compare the antiproliferative effects of rapamycin after exposure for 1 and 7 days. Results. Two days after ARF, GFR was reduced severely but comparably in vehicle and rapamycin rats. In controls, GFR began to increase after day 2 and was normal by day 6. In rapamycin rats, GFR did begin to improve until after day 4 and reached normal values by day 7. In controls, many proliferating tubular cells were present in outer medulla on day 2, after which proliferation progressively decreased. By contrast, in rapamycin rats, proliferating cells were sparse on day 2, but then increased substantially through days 4 and 6. Cultured MPT cells exposed to rapamycin for 7 days were ∼10-fold more resistant to the antiproliferative effects of rapamycin than cells exposed for 1 day. Conclusions. Rapamycin delays but does not prevent renal recovery after ARF. MPT cells become resistant to rapamycin after prolonged exposure. We speculate that the ultimate recovery of renal function after ARF is due to the development of acquired tubular cell resistance to rapamycin.

Role of transforming growth factor beta-1 in peritonitis-induced adhesions.

Peritonitis is a major cause of intra-abdominal adhesion formation. The overexpression of transforming growth factor beta-l (TGF-Pl), a potent mitogen, chemoattractant, and stimulant for collagen synthesis by fibroblasts, has been linked to tissue fibrosis at various sites throughout the body including peritoneal adhesion formation. Hence we hypothesized that the mechanism(s) involved in peritonitis-induced adhesion formation may be mediated through the upregulation of TGF-β expression. Peritonitis was induced in rats by cecal ligation and puncture, while a control group underwent sham operation. Adhesions were scored and harvested from both groups at 0,6 and 12 hours and at 1,2,4, 7, and 28 days. Tissue expression of TGF-PI mRNA was determined by quantitative reverse transcription-polymerase chain reaction and TGF-β protein was localized by immunohistochemical analysis. Serum and peritoneal fluid TGF-β concentrations were quantified by enzyme-linked immunosorbent assay. Compared with sham operation, peritonitis was associated with a significantly greater incidence of abdominal adhesions and a significant increase in the levels of TGF-β 1 mRNA expression at days 2,4, and 7. Immunostaining intensity of TGF-β in adhesions from the peritonitis group also steadily rose through day 7. In peritoneal fluid, the ratio of active:total TGF-βl was significantly increased in the peritonitis group on days 1, 2, and 4 compared with the sham group. These results suggest that peritonitis is associated with the upregulation of TGF-βl, a mechanism that may exacerbate adhesion formation.

Topical H2 Antagonist Prevents Periodontitis in a Rabbit Model

ABSTRACT Cimetidine is a powerful H2 receptor antagonist that eliminates histamines effects on chemotaxis, phagocytosis, and superoxide anion production by phagocytes. The purpose of this study was to analyze the clinical and histopathological changes associated with experimental periodontitis in rabbits in response to topically applied cimetidine. Experimental periodontitis was induced in 21 New Zealand White rabbits using Porphyromonas gingivalis (109 CFU) topically applied three times a week for a 6-week period to previously ligatured teeth. Topical application of cimetidine in a liposome carrier for the prevention of periodontitis was evaluated in four groups of four animals each: 1, 10, and 100 mg/ml and no treatment (positive control). In addition, there was a vehicle group (n = 3) that received liposome preparation (carrier) only, and two animals with ligature application alone served as negative controls. Periodontal disease was quantified by direct visualization and radiographical evaluation of bone loss on defleshed skulls and by histological analyses of sections stained with hematoxylin-eosin and tartrate-resistant acid phosphatase. In the no-treatment (positive control) and liposome (vehicle) groups, direct visualization and radiological measurements revealed statistically significant bone loss compared to the negative control. Application of cimetidine at all concentrations tested inhibited inflammation and bone loss by >90%. Histological findings revealed that ligated sites of the positive control and vehicle groups showed significant reduction in bone level (P < 0.05) compared to the three cimetidine groups, with a marked decrease in inflammation. The findings of this study provide morphological and histological evidence that topically active cimetidine is a potent inhibitor of P. gingivalis-elicited periodontal inflammation, arresting and/or preventing tissue destruction and influencing cell populations present in the inflammatory cell infiltrate.

On the dynamics of nitrite, nitrate and other biomarkers of nitric oxide production in inflammatory bowel disease

Nitrite and nitrate are frequently used surrogate markers of nitric oxide (NO) production. Using rat models of acute and chronic DSS-induced colitis we examined the applicability of these and other NO-related metabolites, in tissues and blood, for the characterization of inflammatory bowel disease. Global NO dynamics were assessed by simultaneous quantification of nitrite, nitrate, nitroso and nitrosyl species over time in multiple compartments. NO metabolite levels were compared to a composite disease activity index (DAI) and contrasted with measurements of platelet aggregability, ascorbate redox status and the effects of 5-aminosalicylic acid (5-ASA). Nitroso products in the colon and in other organs responded in a manner consistent with the DAI. In contrast, nitrite and nitrate, in both intra- and extravascular compartments, exhibited variations that were not always in step with the DAI. Extravascular nitrite, in particular, demonstrated significant temporal instabilities, ranging from systemic drops to marked increases. The latter was particularly evident after cessation of the inflammatory stimulus and accompanied by profound ascorbate oxidation. Treatment with 5-ASA effectively reversed these fluctuations and the associated oxidative and nitrosative stress. Platelet activation was enhanced in both the acute and chronic model. Our results offer a first glimpse into the systemic nature of DSS-induced inflammation and reveal a greater complexity of NO metabolism than previously envisioned, with a clear dissociation of nitrite from other markers of NO production. The remarkable effectiveness of 5-ASA to abrogate the observed pattern of nitrite instability suggests a hitherto unrecognized role of this molecule in either development or resolution of inflammation. Its possible link to tissue oxygen consumption and the hypoxia that tends to accompany the inflammatory process warrants further investigation.

The role of p21ras in pancreatic neoplasia and chronic pancreatitis

K-ras mutations have been detected in both ductal cell carcinoma and intraductal papillary mucinous tumor (IPMT) of pancreas. The frequency of this mutation in ductal cell carcinoma is high, whereas in IPMT, it is variable. It has been suggested that the relatively high frequency of this mutation in ductal cell carcinomas compared with IPMT may account for the differences in biological behavior between these tumor types. More recently, the significance of K-ras mutations in pancreatic tissue has been questioned with the demonstration of this mutation in nonneoplastic pancreata. The current study aims to estimate the relative frequency and evaluate the biological significance of K-ras gene mutations in these neoplasms by performing polymerase chain reaction (PCR) assays of microdissected areas of IPMT, ductal cell carcinomas, and resected chronic pancreatitis. The study also investigates whether alterations of p21ras occur in K-ras mutation-negative cases by using immunohistochemical staining for K-, N- and H-ras. K-ras codon 12 mutations were found almost as frequently in IPMT (71%) as in ductal cell carcinomas (78%). They were also associated with the earliest morphological lesion, flat mucinous change. This mutation also was detected in 42% of cases of chronic pancreatitis. Expression of p21ras was found to correlate closely with K-ras mutation status in IPMT and ductal cell carcinoma. Negative staining for pan-ras, H-ras, and N-ras in cases with wild-type K-ras genes suggests that alternative routes of ras gene alteration are not operative in IPMT or ductal carcinoma. The findings suggest that K-ras activation is frequently associated with both IPMT and ductal cell carcinoma. Its high prevalence in nonneoplastic pancreata suggests that it is also associated with self-limited morphological lesions of the pancreas that do not progress to malignancy.