Immunomodulatory effect of pentoxifylline in suppressing experimental autoimmune myocarditis

NF-κB c-Rel Is a Potential Therapeutic Target for Acute Corneal Transplant Rejection

Purpose

The purpose of this study was to determine the role of nuclear factor kappa B (NF-κB) c-Rel during acute corneal transplant rejection and whether targeting c-Rel can reduce corneal transplant rejection.

Methods

Allogeneic corneal transplantation was performed in wild-type and c-Rel-deficient mice. Corneal graft survival rate, opacity, neovascularization, and edema were evaluated by slit-lamp microscopy. Adeno-associated virus 6 (AAV6) expressing c-Rel-specific small hairpin RNA (AAV6-shRel) and the small-molecule compound pentoxifylline (PTXF) were used to reduce c-Rel expression. Enzyme-linked immunosorbent assay was used to determine the expression of inflammatory cytokines. c-Rel expression was determined by quantitative RT-PCR and western blot. The effect of c-Rel inhibition on corneal transplant rejection was examined using a mouse model of acute allogeneic corneal transplantation. Tear production and corneal sensitivity were measured to determine the potential toxicity of AAV6-shRel and PTXF.

Results

The expression of c-Rel and its inflammatory targets was increased in both mice and patients with corneal transplant rejection. Loss of c-Rel reduced corneal transplant rejection in mouse. Both AAV6-shRel and PTXF were able to downregulate the expression of c-Rel and its inflammatory targets in vitro. Treatment with AAV6-shRel or PTXF reduced corneal transplant rejection in mouse and downregulated the expression of inflammatory cytokines in peripheral blood mononuclear cells from patients with corneal transplant rejection. Treatment with AAV6-shRel or PTXF displayed no side effects on tear production or corneal sensitivity.

Conclusions

Increased expression of c-Rel is a risk factor for acute corneal transplant rejection, and targeting c-Rel can efficiently reduce corneal transplant rejection.

Successful management of feline pemphigus foliaceus with pentoxifylline and topical hydrocortisone aceponate

The treatment regimen for feline pemphigus foliaceus (PF), an autoimmune disease caused by auto-antibodies against proteins of the desmosome junction, usually includes high doses of oral or parenteral immunosuppressive drugs, typically glucocorticoids. This case adds to a growing body of evidence that topical hydrocortisone aceponate is effective for the treatment of feline PF, and demonstrates the practical use of a non-invasive diagnostic method for histopathology when owners refuse a biopsy to support a clinical diagnosis of PF. Finally, this case highlights an international trend of owner-initiated treatment of feline infectious peritonitis (FIP) using unlicensed, unregistered drugs.

Interleukin 6 destabilizes atherosclerotic plaques by downregulating prolyl-4-hydroxylase α1 via a mitogen-activated protein kinase and c-Jun pathway

Interleukin 6 (IL-6) is a pivotal cytokine that regulates extracellular matrix metabolism by ameliorating the modification of collagen content, important in fibrous caps of atherosclerotic plaque. Prolyl-4-hydroxylase α1 (P4Hα1) is a key intracellular enzyme required for synthesis of collagen in animals. We investigated the relationship of IL-6 and P4Hα1 in atherosclerosis-prone mice and human aortic smooth muscle cells (HASMCs). Apolipoprotein E (ApoE)-/- mice were fed a high-fat diet and a perivascular constrictive silica collar was placed on the right common carotid artery to induce atherosclerotic lesions, then mice were divided into two groups for transfection with empty lentivirus or IL-6 lentivirus. HASMCs were transfected with small interfering RNA or treated with recombinant human IL-6. IL-6 significantly downregulated collagen, P4Hα1 and smooth muscle cell contents in atherosclerotic mouse arteries. Macrophage and lipid contents in the atherosclerotic area were significantly increased with IL-6 treatment. IL-6 significantly downregulated P4Hα1 expression in HASMCs through an RAF-MEK1/2-ERK1/2 mitogen-activated protein kinase (MAPK) pathway, and c-Jun was involved in the process. Our findings highlight IL-6 destabilize atherosclerotic plaques in mice by downregulating P4Hα1 via an RAF-MEK1/2-ERK1/2 MAPK and c-Jun pathway.

Pentoxifylline inhibits hepatic stellate cells proliferation via the Raf/ERK pathway

Pentoxifylline (PTX), which is a xanthine derivative, is a well-known suppressor of tumor necrosis factor-alpha (TNF-alpha) production in inflammatory cells and has also been shown to inhibit collagen synthesis in hepatic stellate cells (HSCs) in vitro. The present study aimed to evaluate the effects of PTX on proliferation in HSCs as mediated by the Raf/MEK/extracellular-signal-regulated kinase (ERK) signaling pathway. The rat hepatic stellate cell line T6 and activated primary rat HSCs were used in this study. The proliferation rate of the cells treated with 1 mM PTX significantly decreased compared with that of the control in T6 cells (78.3 ± 6.03% at 12 h, 61.0 ± 7.55% at 24 h, and 44.7 ± 2.08% at 48 h, p < 0.05). PTX (1 mM) also decreased the fraction of the HSC population in the S and G2/M-phases of the cell cycle in primary activated rat HSCs. The Raf-1 inhibitor GW5074 and the ERK inhibitor U0126 had inhibitory effects that were similar to those of PTX on HSC proliferation. In addition, PTX inhibited the phosphorylation of Raf-1 (p-Raf-1) and ERK (p-ERK) in a dose- and time-dependent manner in HSCs. These data provide evidence that PTX suppresses HSC proliferation via the Raf/MEK/ERK pathway.

Beta2-Adrenergic agonists suppress rat autoimmune myocarditis: potential role of beta2-adrenergic stimulants as new therapeutic agents for myocarditis

BACKGROUND

The therapeutic potential of beta2-adrenergic receptor (AR) agonists in the treatment of autoimmune diseases has been reported. However, the role of these drugs in the myocardial structure-induced autoimmune process, which is thought to play a crucial role in the progression of myocarditis to subsequent complications, has not been elucidated.

METHODS AND RESULTS

Experimental autoimmune myocarditis (EAM) was induced in rats by immunization with cardiac myosin. On daily administration from day 0 after immunization, the beta2-selective AR agonists formoterol or salbutamol ameliorated EAM on day 21 and increased myocardial interleukin-10/interferon-gamma mRNA levels. Propranolol, a nonselective beta-AR antagonist, aggravated EAM on day 21 and decreased mRNA levels, whereas metoprolol, a beta1-selective AR antagonist, showed no effect. These results were reflected in vivo by the proliferation of cardiac myosin-primed lymph node cells from drug-treated rats. In vitro addition of beta2-selective AR agonists inhibited the activation of cardiac myosin fragment-specific myocarditogenic T lymphocytes, and this effect was reversed by ICI118,551, a beta2-selective AR antagonist. Furthermore, treatment with 2 different beta2-selective AR agonists starting on day 14 also ameliorated EAM on day 21.

CONCLUSIONS

beta2-AR stimulation suppressed the development of EAM by inhibiting cardiac myosin-specific T-lymphocyte activation in lymphoid organs and by shifting the imbalance in Th1/Th2 cytokine toward Th2 cytokine. Furthermore, it also ameliorated established myocardial inflammation. beta2-AR-stimulating agents may represent important immunomodulators of the cardiac myosin-induced autoimmune process and have potential as a new therapy for myocarditis.

The nonspecific anti-inflammatory therapy with methotrexate for patients with chronic heart failure

BACKGROUND

Inflammatory mediators play an important role in the pathogenesis of chronic heart failure (CHF). Methotrexate (MTX) is used in the treatment of inflammatory-mediated diseases (eg, rheumatoid arthritis) because it modulates the expression of numerous inflammatory cytokines. However, no studies have assessed the effects of MTX on plasma levels of inflammatory mediators in patients with CHF.

METHODS

In a prospective, randomized, placebo-controlled, single-blind study, 71 patients receiving conventional treatment were randomly allocated to either MTX group (7.5 mg once a week, n = 35) or placebo group (n = 36) with a follow-up of 12 weeks. The effects of MTX on plasma cytokine expression, left ventricular ejection fraction, left ventricular end-diastolic dimension, New York Heart Association (NYHA) functional class, 6-minute walk test distance, and quality of life (QOL) were determined in patients with CHF.

RESULTS

Sixty-two patients completed the study. The circulating levels of inflammatory mediators in patients with CHF were markedly elevated compared with healthy controls (P < or = .002). Methotrexate (n = 30) reduced plasma levels of tumor necrosis factor alpha (-15.6%, P < .05), interleukin 6 (-21.8%, P < .01), monocyte chemoattractant protein-1 (-22.6%, P < .01), soluble intercellular adhesion molecule-1 (-19.2%, P < .05), and C-reactive protein (-27.2%, P < .01) compared with baseline. Furthermore, interleukin 10 (15.8 %, P < .05) and soluble IL-1 receptor antagonist (36.1%, P < .01) expression was increased, whereas improvements in NYHA classification, 6-minute walk test distance, and QOL were found compared with baseline. Monocyte chemoattractant protein-1 expression was lower and soluble IL-1 receptor antagonist expression higher in the MTX than placebo group (n = 32). Furthermore, the left ventricular ejection fraction, left ventricular end-diastolic dimension, and incidence of main adverse cardiac events between the 2 groups were similar.

CONCLUSION

These results suggest that the addition of MTX to conventional therapy for CHF has significant anti-inflammatory effects and improves NYHA functional class, 6-minute walk test distance, and QOL.

Roles of tumor necrosis factor alpha (TNF-alpha) and the p55 TNF receptor in CD1d induction and coxsackievirus B3-induced myocarditis

Giving C57BL/6 mice 10(4) PFU of coxsackievirus B3 (H3 variant) fails to induce myocarditis, but increasing the initial virus inoculum to 10(5) or 10(6) PFU causes significant cardiac disease. Virus titers in the heart were equivalent at days 3 and 7 in mice given all three virus doses, but day 3 titers in the pancreases of mice inoculated with 10(4) PFU were reduced. Tumor necrosis factor alpha (TNF-alpha) concentrations in the heart were increased in all infected mice, but cytokine levels were highest in mice given the larger virus inocula. TNF-alpha(-/-) and p55 TNF receptor-negative (TNFR(-/-)) mice developed minimal myocarditis compared to B6;129 or C57BL/6 control mice. p75 TNFR(-/-) mice were as disease susceptible as C57BL/6 animals. No significant differences in virus titers in heart or pancreas were observed between the groups, but C57BL/6 and p75 TNFR(-/-) animals showed 10-fold more inflammatory cells in the heart than p55 TNFR(-/-) mice, and the cell population was comprised of high concentrations of CD4(+) gamma interferon-positive and Vgamma4(+) cells. Cardiac endothelial cells isolated from C57BL/6 and p75 TNFR(-/-) mice upregulate CD1d, the molecule recognized by Vgamma4(+) cells, but infection of TNF(-/-) or p55 TNFR(-/-) endothelial cells failed to upregulate CD1d. Infection of C57BL/6 endothelial cells with a nonmyocarditic coxsackievirus B3 variant, H310A1, which is a poor inducer of TNF-alpha, failed to elicit CD1d expression, but TNF-alpha treatment of H310A1-infected endothelial cells increased CD1d levels to those seen in H3-infected cells. TNF-alpha treatment of uninfected endothelial cells had only a modest effect on CD1d expression, suggesting that optimal CD1d upregulation requires both infection and TNF-alpha signaling.

Gene expression of cardiac mast cell chymase and tryptase in a murine model of heart failure caused by viral myocarditis

This study examined the gene expression of mouse mast cell proteases to clarify their role in the pathophysiology of viral myocarditis. Male DBA/2 mice were inoculated intraperitoneally with the encephalomyocarditis virus and the gene expression of mast cell chymase, mouse mast cell protease (mMCP)-4 and -5, and tryptase, mMCP-6, matrix metalloproteinase (MMP)-9 and type-I procollagen was measured by real-time quantitative RT-PCR analysis. The gene expression of mMCP-4, -5 and -6 mRNA was increased at 5 days, and continued to increase to day 14, coinciding with a prominent inflammatory reaction and extensive myocardial necrosis and fibrosis. The gene expression of MMP-9 was also increased, and there was a significant correlation between upregulation of mast cell proteases and MMP-9. The gene expression of type-I procollagen was increased at 5 days and continued to increase to day 14, suggesting that a fibrotic process had already begun during the acute stage of viral myocarditis. These findings suggest that mast cell chymase and tryptase participate in the acute inflammation and remodeling process of viral myocarditis.

HIV-related cardiovascular disease and drug interactions

HIV infection is a global public health issue that is frequently associated with cardiovascular involvement. These HIV-associated cardiovascular manifestations are often clinically occult or attributed incorrectly to other non-cardiac disease processes. A heightened awareness and routine screening for cardiovascular involvement in HIV-infected patients leads to earlier detection and the hope for a reduction in associated morbidity and mortality. Left ventricular dysfunction, an independent predictor of mortality in HIV-infected patients, is the result of many causes in this population and may result in dilated cardiomyopathy and congestive heart failure in about 10% of patients. Other HIV-associated cardiovascular problems include infective endocarditis, cardiovascular malignancy, pulmonary arterial hypertension, vasculitis, pericardial effusion, premature atherosclerosis, and arrhythmias. HIV-associated cardiovascular emergencies include congestive heart failure, pulmonary edema, supraventricular and ventricular arrhythmias, endocarditis, and tamponade. Anti-infective and immunomodulatory therapies may be particularly helpful in this population to reduce associated cardiovascular disease. Highly active antiretroviral therapy may result in lipodystrophy, hyperlipidemia, truncal adiposity, and insulin resistance that can be improved by physical activity and training programs. Cardiovascular complications of therapeutic drugs in HIV-infected patients include torsade de pointes, congestive heart failure, dyslipidemia, accelerated atherosclerosis, and myocardial infarction. In summary, cardiovascular complications are important contributors to morbidity and mortality in HIV-infected patients that can be detected early in many cases and treated effectively.

Ongoing Myocardial Damage in Chronic Heart Failure is Related to Activated Tumor Necrosis Factor and Fas/Fas Ligand System

BACKGROUND

Elevated concentrations of cardiac troponin T and heart-type fatty acid-binding protein (H-FABP) identify patients with chronic heart failure (CHF) and ongoing myocardial damage (OMD) who are at increased risk for future cardiac events. Cardiomyocyte necrosis and/or apoptosis via activated tumor necrosis factor (TNF) and the Fas/Fas ligand (FasL) system may be related to the development of OMD.

METHODS AND RESULTS

The serum concentrations of H-FABP, a sensitive marker of membrane damage of cardiomyocytes, soluble Fas (sFas) and TNF-alpha were measured in 38 patients with CHF. The concentrations of H-FABP, TNF-alpha and s-Fas in patients with New York Heart Association (NYHA) III + IV were all significantly higher than in those patients in NYHA II (H-FABP; III + IV 9.3+/-5.9 vs II 5.1+/-1.8 ng/ml, p=0.003, TNF-alpha; III + IV 10.5+/-3.8 vs II 8.0+/-2.7 pg/ml, p=0.02, sFas; III + IV 3.36+/-1.37 vs II 2.58 +/-0.84 ng/ml, p=0.03). Increased concentrations of H-FABP significantly correlated with the concentrations of TNF- alpha (r=0.57, p=0.0001) and sFas (r=0.69, p<0.0001), independent of renal function.

CONCLUSION

OMD detected by H-FABP, a marker of membrane damage, is related to activated TNF and the Fas/FasL system, which suggests a pathophysiological role of cardiomyocyte necrosis and/or apoptosis in patients with worsening heart failure.

Monomethoxypolyethylene Glycol-Modified Cardiac Myosin Treatment Blocks the Active and Passive Induction of Experimental Autoimmune Myocarditis

BACKGROUND

Injecting various protein antigens conjugated to monomethoxypolyethylene glycol (mPEG) results in antigen-specific tolerance to subsequent immunization. In the present study the ability of mPEG-modified cardiac myosin (CM) to block the development of experimental autoimmune myocarditis (EAM) induced by CM immunization or by the transfer of lymphocytes from CM-immunized donors was studied.

METHODS AND RESULTS

A/J mice were injected with mPEG-CM before active or passive EAM induction. We examined the suppressive mechanism by the transfer of lymphocytes from mPEG-CM-treated mice into naïve mice. To ascertain the cells responsible for suppressing EAM induction, in vivo or in vitro depletion of CD4(+) or CD8(+) T cells was performed. mPEG-CM administered before active or passive EAM induction markedly suppressed the incidence and severity of EAM and reduced CM-specific antibody responses. When lymphocytes from mPEG-CM treated mice were transferred into naïve mice that were then immunized with CM, the suppressive effect was recapitulated.

CONCLUSIONS

mPEG-CM treatment blocked the active and passive induction of EAM.