Comparative efficacy of a secretory phospholipase A2 inhibitor with conventional anti-inflammatory agents in a rat model of antigen-induced arthritis

INTRODUCTION: Previously, secretory phospholipase A(2 )(sPLA(2)) inhibition has been used as an adjunct to conventional rheumatoid arthritis therapy in human clinical trials without significant improvement of arthritic pathology. In this study, we compared the efficacy of a potent and orally active group IIa secretory phospholipase A(2 )inhibitor (sPLA(2)I) to conventional anti-arthritic agents; infliximab, leflunomide and prednisolone, in a rat model of antigen-induced arthritis. METHODS: Initially, to establish efficacy and dose-response, rats were orally dosed with the sPLA(2)I (1 and 5 mg/kg) two days prior to arthritis induction, and then daily throughout the 14-day study period. In the second trial, rats were orally dosed with the sPLA(2)I (5 and 10 mg/kg/day) beginning two days after the induction of arthritis, at the peak of joint swelling. Separate groups of rats were also dosed with the tumour necrosis factor-alpha (TNF-α) inhibitor infliximab (single 3 mg/kg i.v. injection), leflunomide (10 mg/kg/day, oral) or prednisolone (1 mg/kg/day, oral) at this same time point and used as comparative treatments. RESULTS: In the pathology prevention trial, both 1 and 5 mg/kg dose groups of sPLA(2)I demonstrated a significant reduction in joint swelling and gait disturbances; however, only the higher 5 mg/kg dose resulted in significantly reduced histopathology scores. In the post-induction trial, rats dosed with sPLA(2)I showed a significant improvement in joint swelling and gait scoring, whereas none of the conventional therapeutics achieved a significant decrease in both of these two disease markers. Histopathological scoring at the end-point of the study demonstrated significantly reduced median scores in rats treated with 10 mg/kg sPLA(2)I and leflunomide. CONCLUSIONS: The results from this study suggest a pathogenic role for sPLA(2 )enzymes in this model of arthritis in rats, and the potential clinical utility of sPLA(2 )inhibition as a safer, and more effective, alternative to conventional anti-arthritic therapeutics

Retinal Vascular Fractal Dimension, Childhood IQ, and Cognitive Ability in Old Age: The Lothian Birth Cohort Study 1936

<div><p>Purpose</p><p>Cerebral microvascular disease is associated with dementia. Differences in the topography of the retinal vascular network may be a marker for cerebrovascular disease. The association between cerebral microvascular state and non-pathological cognitive ageing is less clear, particularly because studies are rarely able to adjust for pre-morbid cognitive ability level. We measured retinal vascular fractal dimension (<i>D</i>_<i>f</i>) as a potential marker of cerebral microvascular disease. We examined the extent to which it contributes to differences in non-pathological cognitive ability in old age, after adjusting for childhood mental ability.</p><p>Methods</p><p>Participants from the Lothian Birth Cohort 1936 Study (LBC1936) had cognitive ability assessments and retinal photographs taken of both eyes aged around 73 years (<i>n</i> = 648). IQ scores were available from childhood. Retinal vascular <i>D</i>_<i>f</i> was calculated with monofractal and multifractal analysis, performed on custom-written software. Multiple regression models were applied to determine associations between retinal vascular <i>D</i>_<i>f</i> and general cognitive ability (<i>g</i>), processing speed, and memory.</p><p>Results</p><p>Only three out of 24 comparisons (two eyes × four <i>D</i>_<i>f</i> parameters × three cognitive measures) were found to be significant. This is little more than would be expected by chance. No single association was verified by an equivalent association in the contralateral eye.</p><p>Conclusions</p><p>The results show little evidence that fractal measures of retinal vascular differences are associated with non-pathological cognitive ageing.</p></div

Transforming growth factor-beta(1) induces alpha-smooth muscle actin expression and fibronectin synthesis in cultured human retinal pigment epithelial cells

Proliferative vitreoretinopathy is a serious complication of retinal detachment, yet its pathogenesis is not fully understood. Retinal pigment epithelial cells and glial cells are found in the fibrous membranes in proliferative vitreoretinopathy. Many cytokines are involved in the pathology. Transforming growth factor (TGF)-beta, a cytokine found in serum, has been shown to be an important factor regulating the synthesis of fibrous extracellular matrix in proliferative vitreoretinopathy.Cultured human retinal pigment epithelial cells were used in the experiments. The effects of TGF-beta1 on phenotype and function in retinal pigment epithelial cells were recorded as changes in the expression of alpha-smooth muscle actin and fibronectin synthesis using immunohistochemistry and enzyme-linked immunosorbent assay, respectively.TGF-beta1 induced the expression of alpha-smooth muscle actin (P < 0.0001, n = 3), and significantly increased the synthesis of fibronectin by cultured human retinal pigment epithelial cells (P < 0.01, n = 4).Elevated levels of TGF-beta1 in proliferative vitreoretinopathy may contribute to phenotype changes in retinal pigment epithelial cells leading to matrix deposition and contraction. Since the elevated levels of TGF-beta1 may emanate from a number of diverse sources in proliferative vitreoretinopathy, developing an antagonist to TGF-beta1 may offer an approach to the treatment of proliferative vitreoretinopathy

Detection of anti-TNFa activity in canine hyperimmune serum using a TNFa inhibition assay

Background: Increased serum tumor necrosis factor-α (TNFα) activity has been associated with onset of serious inflammatory diseases in dogs. Development of treatment with TNFα-antagonists has been limited by the unavailability of suitable reagents and potency assays for TNFα. Objectives: The objectives of this study were to optimize a cell-based assay to measure anti-TNFα activity in serum and plasma from hyperimmune (vaccinated with an Escherichia coli J5 bacterin) and unvaccinated canine donors; to use the assay to determine whether hyperimmune serum inhibits TNFα activity in vivo; and to determine whether soluble TNF receptor-1 (sTNFR1, a naturally occurring TNFα antagonist) contributes to anti-TNFα activity. Methods: Commercial plasma and serum from hyperimmune-frozen plasma (HFP) donors and unvaccinated fresh-frozen plasma (FFP) donors were used in the study. An L929-cell TNFα-inhibition assay (LTIA) was optimized to measure anti-TNFα activity. Using a rat subcutaneous pouch model of inflammation, the effects of HFP, FFP, a synthetic TNFα antagonist (Etanercept), and carprofen on TNFα activity were compared in vivo. Immunofluorescence was used to measure soluble sTNFR1 concentration. Results: Using the optimized LTIA, HFP serum but not FFP serum decreased canine TNFα activity (P<.01). HFP plasma and Etanercept (but not FFP plasma or carprofen) significantly decreased TNFα activity in pouch exudates (P<.05). A significantly higher concentration of sTNFR1 was found in HFP than FFP serum. Conclusions: Using the LTIA, anti-TNFα activity is readily measured in canine serum and inflammatory exudates. sTNFR1 appears to contribute to anti-TNFα activity in HFP serum. These results suggest HFP should be investigated further as a potential immunotherapeutic agent for controlling canine diseases in which TNFα is implicated

Pirfenidone attenuates ischaemia-reperfusion injury in the rat small intestine

1. Pirfenidone, an antifibrotic compound with anti-inflammatory effects, has been investigated in a rat model of acute experimental ischaemia-reperfusion injury of the small intestine. 2. Occlusion of the superior mesenteric artery in young adult female rats for 30 min followed by reperfusion for 120 min induced significant local and systemic effects, including tissue haemorrhage with oedema, elevated serum concentrations of tumour necrosis factor (TNF)-α, neutropenia, hypotension and bradycardia. 3. Administration of pirfenidone (200 mg/kg, p.o., i.v. or i.p.) 30 min before occlusion completely inhibited the increase in serum TNF-α concentrations. Pirfenidone inhibited, but did not completely prevent, tissue damage in the small intestine, as well as hypotension and oedema, but neutropenia and bradycardia were not significantly changed by treatment. 4. Thus, pirfenidone effectively moderates both local and some systemic effects of ischaemia-reperfusion injury in the rat small intestine model

The role of the complement system in ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury is a common clinical event with the potential to seriously affect, and sometimes kill, the patient. Interruption of blood supply causes ischemia, which rapidly damages metabolically active tissues. Paradoxically, restoration of blood flow to the ischemic tissues initiates a cascade of pathology that leads to additional cell or tissue injury. I/R is a potent inducer of complement activation that results in the production of a number of inflammatory mediators. The use of specific inhibitors to block complement activation has been shown to prevent local tissue injury after I/R. Clinical and experimental studies in gut, kidney, limb, and liver have shown that I/R results in local activation of the complement system and leads to the production of the complement factors C3a, C5a, and the membrane attack complex. The novel inhibitors of complement products may find wide clinical application because there are no effective drug therapies currently available to treat I/R injuries

A potential link between the C5a receptor 1 and the β1-adrenoreceptor in the mouse heart

Purpose: Inflammation may contribute to the pathogenesis of specific cardiovascular diseases, but it is uncertain if mediators released during the inflammatory process will affect the continued efficacy of drugs used to treat clinical signs of the cardiac disease. We investigated the role of the complement 5a receptor 1 (C5aR1/CD88) in the cardiac response to inflammation or atenolol, and the effect of C5aR1 deletion in control of baseline heart rate in an anesthetized mouse model. Methods: An initial study showed that PMX53, an antagonist of C5aR1 in normal C57BL6/J (wild type, WT) mice reduced heart rate (HR) and appeared to have a protective effect on the heart following induced sepsis. C5aR1 knockout (CD88-/-) mice had a lower HR than wild type mice, even during sham surgery. A model to assess heart rate variability (HRV) in anesthetized mice was developed to assess the effects of inhibiting the β1-adrenoreceptor (β1-AR) in a randomized crossover study design. Results: HR and LF Norm were constitutively lower and SDNN and HF Norm constitutively higher in the CD88-/- compared with WT mice (P 0.05), except for the reduced LF/HF (Lower frequency/High frequency) ratio (P< 0.05) at 60 min post-atenolol, suggesting increased parasympathetic tone of the heart due to the effect of atenolol administration. The HR of the WT mice were lower post atenolol compared to the CD88-/- mice (P = 0.001) but the HRV of CD88-/- mice were significantly increased (P< 0.05), compared with WT mice. Conclusion: Knockout of the C5aR1 attenuated the effect of β1-AR in the heart, suggesting an association between the β1-AR and C5aR1, although further investigation is required to determine if this is a direct or causal association

Inhibition of immune-complex mediated dermal inflammation in rats following either oral or topical administration of a small molecule C5a receptor antagonist

1. Initiation of a peritoneal Arthus reaction by deposition of immune-complexes results in vascular leakage, polymorphonuclear leukocyte (PMN) infiltration, and tumour necrosis factor α (TNFα) and interleukin-6 (IL-6) production. We now demonstrate in rats that oral administration of the C5a receptor antagonist AcPhe[Orn-Pro-D-Cyclohexylalanine-Trp-Arg] (AcF-[OPdChaWR]; 1 – 10 mg kg(−1) 30 min prior to immune-complex deposition) inhibits these inflammatory markers in the peritoneal Arthus reaction. 2. Initiation of a dermal Arthus reaction resulted in a significant increase in vascular leakage, PMN infiltration, systemic production of TNFα and pathological changes in the dermis. 3. Pretreatment of rats with AcF-[OPdChaWR] either intravenously (1 mg kg(−1) 10 min prior to immune-complex deposition) or orally (1 – 10 mg kg(−1) 30 min prior to immune-complex deposition) significantly inhibited immune-complex mediated dermal vascular leakage and systemic cytokine production. Topical pretreatment with AcF-[OPdChaWR] (400 μg site(−1) in 10% dimethyl sulphoxide 10 min prior to immune-complex deposition) also inhibited vascular leakage, as well as histopathological changes associated with a dermal Arthus reaction. 4. Oral administration of 3 mg kg(−1) AcF-[OPdChaWR] resulted in the appearance of the drug in plasma within 5 min, with peak blood levels ∼0.3 μM reached within 20 min. The plasma elimination half-life was ∼70 min. The oral activity and bioavailability of AcF-[OPdChaWR], its activity when applied topically to the skin, suggest that small molecule C5a receptor antagonists may have therapeutic utility in dermal inflammatory disorders involving complement activation. 5. This is the first demonstration for either an orally or topically active C5a receptor antagonist, and suggests that small molecule C5a antagonists may have therapeutic utility when given by multiple routes of application

Evaluation of a technique to measure heart rate variability in anaesthetised cats

Analysis of heart rate (HR) and heart rate variability (HRV) are powerful tools to investigate cardiac diseases, but current methods, including 24-h Halter monitoring, can be cumbersome and may be compromised by movement artefact. A commercially available data capture and analysis system was used in anaesthetised healthy cats to measure HR and HRV during pharmacological manipulation of HR. Seven healthy cats were subjected to a randomised crossover study design with a 7 day washout period between two treatment groups, placebo and atenolol (1 mg/kg, IV), with the efficacy of atenolol to inhibit beta(1) adrenoreceptors challenged by epinephrine. Statistical significance for the epinephrine challenge was set at P < 0.0027 (Holm-Bonferroni correction), whereas a level of significance of P < 0.05 was set for other variables