Inhibition of the nuclear factor-kappaB signaling pathway by leflunomide or triptolide also inhibits the anthralin-induced inflammatory response but does not affect keratinocyte growth inhibition

Focus on the potential effects of treatments for spondylarthritides on cardiovascular risk

The past years have seen the publication of several studies on seronegative spondylarthritides (SpA) and cardiovascular risk as a result of new insights into the connection between inflammation and atherogenesis. Although the overall cardiovascular disease is a complex entity, chronic inflammation of SpA is known to contribute as an independent risk factor, and new therapies are aimed at reducing this persistent inflammatory status. This review provides an overview of the recent advances in understanding the role of the current therapeutic measures of SpA in preventing or accelerating cardiovascular risk.

Teriflunomide for oral therapy in multiple sclerosis

Teriflunomide, the active metabolite of an approved antirheumatic drug, is an emerging oral therapy for multiple sclerosis (MS). Next to the inhibition of pyrimidine biosynthesis and proliferation of activated lymphocytes, it seems to have multiple anti-inflammatory and immunomodulating effects. Phase II and III clinical trials in relapsing MS demonstrated favorable safety and tolerability of the drug, as well as clinical efficacy, with a significant reduction of relapse rate, comparable with those of the available injectable immunomodulatory agents. While multiple other studies with teriflunomide are currently ongoing, its exact place in future treatment algorithms for MS is difficult to predict. It may be a good alternative for patients wishing to have an oral treatment with relatively large data regarding long-term safety.

Triptolide inhibits IFN-γ signaling via the Jak/STAT pathway in HaCaT keratinocytes

Interferon-gamma (IFN-γ) signaling in keratinocytes plays an important role in IFN-γ-mediated skin inflammation involved in psoriasis. Blocking IFN-γ signal transduction in keratinocytes could be a strategy for controlling inflammatory skin disorders. Tripterygium wilfordii Hook. F. (T. wilfordii) has been used effectively in psoriasis treatment in China. Its therapeutic mechanism on IFN-γ-dependent inflammation has not been elucidated. Triptolide is one of main components of T. wilfordii's antiinflammatory and immune effects. This study aimed to explore the effects of triptolide on an rhIFN-γ-stimulated human keratinocyte cell line (HaCaT) in culture. The expression of IFN-γ receptor α (IFN-γRα), phospho-Janus kinase2 (pJak2), phospho-signal transducer and activator of transcription 1 (pSTAT1) and suppressor of cytokine signaling 1 (SOCS1) was detected by western blotting. The expression of intercellular adhesion molecule-1 (ICAM-1) on the HaCaT cell surface was determined by cell-surface ELISA. The results demonstrated that triptolide inhibited the expression of IFN-γRα (IC₅₀  = 1.37 × 10⁻⁸ M), pJak2 (IC₅₀  = 2.82 × 10⁻⁹ M) and pSTAT1 (IC₅₀  = 1.29 × 10⁻⁹ M) in HaCaT cells. The expression of SOCS1 was up-regulated (ED₅₀  = 3.32 × 10⁻¹¹  M). Triptolide also significantly reduced the expression of ICAM-1 on the HaCaT cell surface (IC₅₀  = 5.82 × 10⁻¹⁰ M). This study suggests that triptolide may contribute to the therapeutic value of T. wilfordii by modulating the IFN-γ signal pathway in IFN-γ-dependent skin inflammatory diseases, including psoriasis.

Leflunomide inhibition of BK virus replication in renal tubular epithelial cells

The immunomodulatory drug leflunomide is frequently used for treating polyomavirus-associated nephropathy, yet its antiviral mechanism is unclear. We characterized the effects of the active leflunomide metabolite A771726 (LEF-A) on the polyomavirus BK (BKV) life cycle in human renal tubular epithelial cells. LEF-A at 10 microg/ml reduced the extracellular BKV load by 90% (IC(90)) but with significant host cytostatic effects. BKV genome replication, late protein expression, and virion assembly and release were inhibited with visible disruption of the nuclear replication architecture. Both host cell and antiviral effects were largely reversed by uridine addition, implicating nonspecific pyrimidine depletion as the major anti-BKV mechanism of leflunomide.

Leflunomide inhibition of BK virus replication in renal tubular epithelial cells

The immunomodulatory drug leflunomide is frequently used for treating polyomavirus-associated nephropathy, yet its antiviral mechanism is unclear. We characterized the effects of the active leflunomide metabolite A771726 (LEF-A) on the polyomavirus BK (BKV) life cycle in human renal tubular epithelial cells. LEF-A at 10 microg/ml reduced the extracellular BKV load by 90% (IC(90)) but with significant host cytostatic effects. BKV genome replication, late protein expression, and virion assembly and release were inhibited with visible disruption of the nuclear replication architecture. Both host cell and antiviral effects were largely reversed by uridine addition, implicating nonspecific pyrimidine depletion as the major anti-BKV mechanism of leflunomide.

A novel hybrid aspirin-NO-releasing compound inhibits TNFalpha release from LPS-activated human monocytes and macrophages

Background

The cytoprotective nature of nitric oxide (NO) led to development of NO-aspirins in the hope of overcoming the gastric side-effects of aspirin. However, the NO moiety gives these hybrids potential for actions further to their aspirin-mediated anti-platelet and anti-inflammatory effects. Having previously shown that novel NO-aspirin hybrids containing a furoxan NO-releasing group have potent anti-platelet effects, here we investigate their anti-inflammatory properties. Here we examine their effects upon TNFα release from lipopolysaccharide (LPS)-stimulated human monocytes and monocyte-derived macrophages and investigate a potential mechanism of action through effects on LPS-stimulated nuclear factor-kappa B (NF-κB) activation.

Methods

Peripheral venous blood was drawn from the antecubital fossa of human volunteers. Mononuclear cells were isolated and cultured. The resultant differentiated macrophages were treated with pharmacologically relevant concentrations of either a furoxan-aspirin (B8, B7; 10 μM), their respective furazan NO-free counterparts (B16, B15; 10 μM), aspirin (10 μM), existing nitroaspirin (NCX4016; 10 μM), an NO donor (DEA/NO; 10 μM) or dexamethasone (1 μM), in the presence and absence of LPS (10 ng/ml; 4 h). Parallel experiments were conducted on undifferentiated fresh monocytes. Supernatants were assessed by specific ELISA for TNFα release and by lactate dehydrogenase (LDH) assay for cell necrosis. To assess NF-κB activation, the effects of the compounds on the loss of cytoplasmic inhibitor of NF-κB, IκBα (assessed by western blotting) and nuclear localisation (assessed by immunofluorescence) of the p65 subunit of NF-κB were determined.

Results

B8 significantly reduced TNFα release from LPS-treated macrophages to 36 ± 10% of the LPS control. B8 and B16 significantly inhibited monocyte TNFα release to 28 ± 5, and 49 ± 9% of control, respectively. The B8 effect was equivalent in magnitude to that of dexamethasone, but was not shared by 10 μM DEA/NO, B7, the furazans, aspirin or NCX4016. LDH assessment revealed none of the treatments caused significant cell lysis. LPS stimulated loss of cytoplasmic IκBα and nuclear translocation of the p65 NF-κB subunit was inhibited by the active NO-furoxans.

Conclusion

Here we show that furoxan-aspirin, B8, significantly reduces TNFα release from both monocytes and macrophages and suggest that inhibition of NF-κB activation is a likely mechanism for the effect. This anti-inflammatory action highlights a further therapeutic potential of drugs of this class.