The Immunosuppressive Activity of Pseudolaric Acid B on T lymphocytes in vitro

Pseudolaric acid B suppresses NSCLC progression through the ROS/AMPK/mTOR/autophagy signalling pathway

Pseudolaric acid B (PAB), an acid isolated from the roots of Pseudolarix kaempferi gorden, has shown antitumour effects through multiple mechanisms of action. The objective of this study was to investigate the anticancer effect of PAB on non-small cell lung cancer (NSCLC) and its underlying mechanism. In our experiments, we observed that PAB decreased cell viability, inhibited colony formation, induced cell cycle arrest, impeded scratch healing, and increased apoptosis in H1975 and H1650 cells. Additionally, PAB treatment enhanced the fluorescence intensity of MDC staining in NSCLC cells, upregulated the protein expression of microtubule-associated protein light chain 3 II (LC3 II), and downregulated the expression of sequestosome 1 (SQSTM1/P62). Combined treatment with PAB and chloroquine (CQ) increased the protein expression levels of LC3 II and P62 while decreasing the apoptosis of H1975 and H1650 cells. Moreover, treatment with PAB led to significant mTOR inhibition and AMPK activation. PAB combined with compound C (CC) inhibited autophagy and apoptosis. Furthermore, PAB treatment increased intracellular reactive oxygen species (ROS) levels in NSCLC cells, which correlated with the modulation of the AMPK/mTOR signalling pathway and was associated with autophagy and apoptosis. Finally, we validated the antitumour growth activity and mechanism of PAB in vivo using athymic nude mice bearing H1975 tumour cells. In conclusion, our findings suggest that PAB can induce apoptosis and autophagic cell death in NSCLC through the ROS-triggered AMPK/mTOR signalling pathway, making it a promising candidate for future NSCLC treatment.

The toxin mimic FS48 from the salivary gland of Xenopsylla cheopis functions as a Kv1.3 channel-blocking immunomodulator of T cell activation

The Kv1.3 channel has been widely demonstrated to play crucial roles in the activation and proliferation of T cells, which suggests that selective blockers could serve as potential therapeutics for autoimmune diseases mediated by T cells. We previously described that the toxin mimic FS48 from salivary gland of Xenopsylla cheopis downregulates the secretion of proinflammatory factors by Raw 264.7 cells by blocking the Kv1.3 channel and the subsequent inactivation of the proinflammatory MAPK/NF-κB pathways. However, the effects of FS48 on human T cells and autoimmune diseases are unclear. Here, we described its immunomodulatory effects on human T cells derived from suppression of Kv1.3 channel. Kv1.3 currents in Jurkat T cells were recorded by whole-cell patch-clamp, and Ca2+ influx, cell proliferation, and TNF-α and IL-2 secretion were measured using Fluo-4, CCK-8, and ELISA assays, respectively. The in vivo immunosuppressive activity of FS48 was evaluated with a rat DTH model. We found that FS48 reduced Kv1.3 currents in Jurkat T cells in a concentration-dependent manner with an IC50 value of about 1.42 μM. FS48 also significantly suppressed Kv1.3 protein expression, Ca2+ influx, MAPK/NF-κB/NFATc1 pathway activation, and TNF-α and IL-2 production in activated Jurkat T cells. Finally, we show that FS48 relieved the DTH response in rats. We therefore conclude that FS48 can block the Kv1.3 channel and inhibit human T cell activation, which most likely contributes to its immunomodulatory actions and highlights the great potential of this evolutionary-guided peptide as a drug template in future studies.

Pseudolaric acid B attenuates atopic dermatitis-like skin lesions by inhibiting interleukin-17-induced inflammation

Pseudolaric acid B (PB), isolated from the extract of the root bark of Pseudolarix kaempferi Gordon, has been used as a traditional remedy for the treatment of skin diseases. However, the information of PB on atopic dermatitis (AD) remains largely unknown. In the present study, oral administration with PB improved the severity scores of AD-like skin lesions dose-dependently in NC/Nga mice through reducing serum IgE, pro-inflammatory cytokines, and the infiltration of inflammatory cells. In addition, PB significantly attenuated the levels of IL-17 and IL-22, and the proportion of Th17 cells in NC/Nga mice, as well as decreased IL-17-induced inflammation in RAW264.7 cells. Moreover, PB inhibited the phosphorylation of IκBα and miR-155 expression both in NC/Nga mice and in IL-17-stimulated RAW264.7 cells, which could be reversed by GW9662, a specific antagonist for PPARγ. The incorporation of GW9662 reversed the inhibitory effect of PB on the RORγ-mediated activation of the Il17 promoter. Transfection with PPARγ luciferase reporter gene further demonstrated the enhancement of PB on PPARγ transactivation. These findings indicate that PB could ameliorate AD-like skin lesions by inhibiting IL-17-induced inflammation in a PPARγ-dependent manner, which would provide experimental evidence of PB for the therapeutic potential on AD and other inflammatory skin diseases.

A Systematic Review of the Immune-Regulating and Anticancer Activities of Pseudolaric Acid B

Cortex pseudolaricis, the root bark of Pseudolarix kaempferi Gord, has been used to treat tinea and other skin diseases for the antimicrobial activities in Traditional Chinese Medicine (TCM). Pseudolaric acid B (PAB) has been identified as the major component responsible for the action of C. pseudolaricis. Recently, PAB has been demonstrated to be used as novel treatments for cancer, immune disorders, inflammatory diseases, and immunosuppression. However, the mechanisms through which PAB exerts its properties are not understood well, and little attention in the literature has been given to review its pharmacological activities before. In this review, we performed a systematic summary of the literature with respect to the anticancer, immunosuppressive and anti-inflammatory properties of PAB and its derivatives. Currently available data suggest that PAB is a promising immunosuppressive and anti-inflammatory agent candidate and should be explored further in cancer treatment and prevention.

Study on the therapeutic mechanisms of pseudolaric acid in mice with allergic contact dermatitis

OBJECTIVE

To study the therapeutic mechanisms of pseudolaric acid on allergic contact dermatitis in mice.

METHODS

A total of 50 BALB/C mice were selected and randomly divided into control group, model group, and treatment A, B, C groups with 10 rats in each group. ACD model was established in model group, and treatment A, B, C groups but not in control group. Model group received no treatment, but treatment A, B, C groups were treated with external application of the concentration of 0.1%, 0.2% and 0.4% of the pseudolaric acid for the lesions of ear skin. And the weight gain and the swelling degree of the mice' ear were recorded, weight of thymus and spleen were measured. Spleen suspension was prepared to test T lymphocyte and B lymphocyte levels of mice in five groups. Changes in serum IFN-γ, IL-4 and IL-10 levels were tested through the enzyme linked immunosorbent assay (ELISA).

RESULTS

The weight gain of mice in model group were significant lower than those of mice in the control group and the treatment A, B, C groups (P < 0.05). Weight gain of mice in treatment A, B groups were significant lower than that of control group (P < 0.05), but the difference in weight gain between treatment C group and control group showed no significant difference (P > 0.05). The swelling degree and the weight of mice ears in model group were significant higher than those of mice in control group and treatment A, B, C groups (P < 0.05). Swelling degree and the weight of mice ears of treatment A, B, C groups were obviously higher than that of control group (P < 0.05). The swelling degree and weight of mice' ears in treatment A, B, C groups were decreased with the increase of the drug dosage, but comparison between A, B and C group showed statistically differences (P < 0.05). The thymus and spleen index of mice in model group were significant higher than those of the other four groups (P < 0.05), among the four groups, thymus and spleen index of treatment A and B group were higher than control group and treatment C group (P < 0.05). The stimulation index of T and B cells of mice in model group was significantly higher than the rest four groups (P < 0.05). The serum IFN-γ level of mice in control group and treatment A, B and C group was obviously lower than that of mice in model group (P < 0.05). The serum IFN-γ level of mice in treatment A, B and C group were decreased with the increasing of the drug dosage, and the level of C group was obviously lower than that of A and B group (P < 0.05).

CONCLUSION

The pseudolaric acid has anti-inflammation and immune adjustment the effects showing a remarkable therapeutic effects for the ACD mice.

Synthesis and biological evaluation of pseudolaric acid B derivatives as potential immunosuppressive agents

Pseudolaric acid B (PB) derivatives with immunosuppressive activity were found by our group. In order to find potential immunosuppressive agents with high efficacy and low toxicity, a series of novel PB derivatives were synthesized and evaluated on their immunosuppressive activities. Most of the synthesized compounds were tested in vitro on murine T and B proliferation. In particular, compound 11 exhibited excellent inhibitory activity toward murine T cells (up to 19-fold enhancement compared to that of mycophenolatemofetil) and little cytotoxicity toward normal murine spleen cells. These experimental data demonstrated that some of these PB derivatives have great potential for future immunosuppressive studies.

A novel Pseudolaric acid B derivative, Hexahydropseudolaric acid B, exterts an immunomodulatory effect in vitro/in vivo evaluation

Identification of immunosuppressants from natural sources has a proven track record in immune mediated disorders. Pseudolaric acid B is a diterpenoid isolated from the roots of Pseudolarix amabilis, possessing potent immunomodulatory effect. However, the cytotoxicity limits its future clinical application. The purpose of this study was to investigate the immunosuppressive activity of Hexahydropseudolaric acid B, a Pseudolaric acid B derivative, on T cell-mediated immune response both in vitro and in vivo, and investigated its immunomodulatory effect to develop a more ascendant immunosuppressive agent. The results showed that Hexahydropseudolaric acid B could exert more preferable immunosuppressive activity and lower cytotoxicity than Pseudolaric acid B. Hexahydropseudolaric acid B significantly inhibited T cell proliferation activated by mitogen and alloantigen without obvious cytotoxicity in vitro. Furthermore, Hexahydropseudolaric acid B could ameliorate ear swelling in a mouse model of 2,4-dinitrofluorobenzene-induced delayed-type hypersensitivity in vivo. Mechanistic study revealed that Hexahydropseudolaric acid B could enhance regulatory T cells via promoting Foxp3 expression and TGF-β level, accompanied by attenuating Akt activation, blocking p38MAPK/MK2-HSP27 signal cascades, and up-regulating PPAR-γ expression. Taken together, these results suggest that Hexahydropseudolaric acid B exerts more preferable immunosuppressive activity than its precursor Pseudolaric acid B by affecting multiple targets, which support the need for continued efforts to characterize the efficacy of HPAB as a promising and safe candidate to treat immune-related diseases.

Pseudolaric acid B inhibits T-cell mediated immune response in vivo via p38MAPK signal cascades and PPARγ activation

AIMS

Pseudolaric acid B (PAB) has been prescribed for its potent immunomodulatory effect. However, the detail of mechanism remains to be demonstrated. The purpose of this study is to further clarify the mechanism of PAB on T-cell mediated immune response in vivo.

MAIN METHODS

Investigations were carried to ascertain the pharmacological effect of PAB in a delayed-type hypersensitivity (DTH) mouse model of T-cell mediated immune response. Histological assessment was examined by hematoxylin and eosin staining. Affymetrix GeneChip® Mouse Genome 430 2.0 arrays were employed to evaluate the expression profile of PAB. Western blot was performed to detect p38MAPK signal cascades, including p38MAPK, ATF-2, MK2, and HSP27. Finally, TNF-α level was analyzed by ELISA, and Jurkat T cells were treated with PAB to determine its role on PPARγ activation using a reporter gene assay.

KEY FINDINGS

The results showed that PAB (5, 10, and 20mg/kg) could lead to a marked improvement for ear swelling and inflammatory infiltrate in DTH mice dose-dependently. According to the associated biological pathways from microarray analysis, PAB resulted in the restoration of abnormal immune-related gene expression linked to MAPK and PPAR signaling pathways. Moreover, PAB inhibited the activation of p38MAPK, ATF-2, MK2, and HSP27 significantly, as well as the production of TNF-α, which was reversed by GW9662, a specific antagonist for PPARγ. In addition, treatment with PAB also increased the transcriptional activity of PPARγ in a dose-dependent manner.

SIGNIFICANCE

These results provide us with novel insights into pharmacological action of PAB as a potential immunomodulator for the treatment of immune-related diseases.