The effects of saikosaponin-d on yeast phagocytosis and degradation in peritoneal macrophages: related increase in Fc receptor expression and altered cytoplasmic organization

Saikosaponins: a potential treatment option for systemic lupus erythematosus

While the exact cause of systemic lupus erythematosus (SLE) is still unknown, modern medicine has a number of effective treatments for this complex disorder. Corticosteroid hormones help reduce inflammation, antimalarial treatments address flare-ups and immunosuppressive medications work to keep the immune system in check. All these therapies are well tolerated, but accompany an increased risk of infection and nephrotoxicity. Recently, several studies showed that a number of natural and herbal products may also help some SLE patients deal with the debilitating symptoms. In this brief report, we proposed a traditional Chinese medicinal herb--Saikosaponins, and discussed its potential as a treatment option for SLE.

Advances in saponin-based adjuvants

Saponins are natural glycosides of steroid or triterpene which exhibited many different biological and pharmacological activities. Notably, saponins can also activate the mammalian immune system, which have led to significant interest in their potential as vaccine adjuvants. The most widely used saponin-based adjuvants are Quil A and its derivatives QS-21, isolated from the bark of Quillaja saponaria Molina, which have been evaluated in numerous clinical trials. Their unique capacity to stimulate both the Th1 immune response and the production of cytotoxic T-lymphocytes (CTLs) against exogenous antigens makes them ideal for use in subunit vaccines and vaccines directed against intracellular pathogens as well as for therapeutic cancer vaccines. However, Quillaja saponins have serious drawbacks such as high toxicity, undesirable haemolytic effect and instability in aqueous phase, which limits their use as adjuvant in vaccination. It has driven much research for saponin-based adjuvant from other kinds of natural products. This review will summarize the current advances concerning adjuvant effects of different kinds of saponins. The structure-activity relationship of saponin adjuvants will also be discussed in the light of recent findings. It is hoped that the information collated here will provide the reader with information regarding the adjuvant potential applications of saponins and stimulate further research into these compounds.

Saikosaponin-d inhibits T cell activation through the modulation of PKCtheta, JNK, and NF-kappaB transcription factor

The effects of saikosaponin-d, a triterpene saponin derived from Bupleurum falcatum L. (Umbelliferae), on the signaling pathways of T cell activation were examined. The results showed that saikosaponin-d potently suppressed both early (CD69) and late (CD71) expressions of mouse T cells stimulated with Con A or PMA. It interfered with PKCtheta translocation from cytosol to membrane fraction and inhibited the phosphorylations of IkappaBalpha and JNK, but not ERK, in PMA-activated mouse T cells. Additionally, it inhibited PMA and ionomycin-stimulated IL-2 production in mouse T cells. In summary, these results indicate that the mechanism by which saikosaponin-d inhibits T cell activation would involve the suppression of CD69 and CD71 expressions and IL-2 production, and the modulation of PKC pathway through PKCtheta, JNK, and NF-kappaB transcription factor. This may herald a novel approach for further studies of saikosaponin-d as a candidate for use in the treatment of inflammatory and autoimmune diseases.

Therapeutic mechanism of Saikosaponin-d in anti-Thy1 mAb 1-22-3-induced rat model of glomerulonephritis

AIMS

Mesangioproliferative glomerulonephritis is a common kidney disease and at present, there is no effective treatment. Our previous studies have demonstrated that Sairei-to can significantly prevent progression of experimental glomerulonephritis in rats. Although we have reported that the active component of Sairei-to in treatment of glomerulonephritis was Saikosaponin-d (Ssd), mechanism of Ssd in prevention of mesangioproliferative glomerulonephritis progression is still unknown. Therefore, current study examines the effects of Ssd on progression of mesangioproliferative glomerulonephritis induced by anti-Thy1 monoclonal antibody 1-22-3 (mAb 1-22-3) in uninephrectomized rats.

METHODS

Eighteen female Wistar rats first received uninephrectomy and mAb 1-22-3 injection and were then divided into 3 groups: treated daily with phosphate-buffered saline (PBS), 0.6 or 1.8 mg/kg of Ssd. Urinary protein concentration and systolic blood pressure were evaluated and the kidneys were collected and subjected to histological and immunohistological evaluation. The mRNA and protein of the kidneys were extracted and subjected to reverse transcriptase polymerase chain reaction and Western blot analysis, respectively.

RESULTS

Ssd reduced the amount of urinary protein and systolic blood pressure. Ssd administration also decreased extracellular matrix expansion, crescentic formation as well as infiltration of macrophages and CD8+ T lymphocytes. Moreover, Ssd significantly reduced expression of transforming growth factor beta 1 (TGF-beta1) and type I collagen in the kidneys.

CONCLUSION

Ssd inhibits the progression of mesangioproliferative glomerulonephritis through reduction of the expression of TGF-beta1 and the infiltration of macrophages and CD8+ T lymphocytes.

Suppressive effects of sairei-to on monoclonal antibody 1-22-3-induced glomerulonephritis: analysis of effective components

The effects of traditional Chinese medicine (Sairei-to) on experimental glomerulonephritis induced in rats by monoclonal antibody (mAb) 1-22-3 injection was examined. The level of proteinuria in the Sairei-to-treated group was significantly lower than that in the PBS treated group. This suppressive effect was caused by the major component of Sairei-to, Syo-saiko-to but not by another component, Gorel-san. The suppressive effect of Syo-saiko-to was identified in its components (Bupleuri radix, Pinelliae tuber and Zingiberis rhizoma), but not in the other combined components (Ginseng radix and Zizyphi fructus). Further study revealed that the suppressive effects of the combined components were mainly derived from Bupleuri radix. It was demonstrated that the actual active ingredient is probably Saikosaponin-d. Light microscopy revealed that Sairei-to and its effective components suppressed the proliferation of mesangial cells and mesangial matrix expansion. Semiquantitative morphological studies of glomerular lesions on the eighth day showed that Syo-saiko-to and its combined components (Bupleuri radix, Zingiberis rhizoma and Pinelliae tuber) suppressed mesangial matrix expansion significantly compared with phosphate-buffered saline control groups (matrix score: 28.0 +/- 19.1 vs 102.3 +/- 14.1; 30.9 +/- 30.1 vs 102.3 +/- 14.1, P < 0.005, respectively). It was concluded that Saikosaponin-d, as well as Bupleuri radix, Syo-saiko-to and Sairei-to can suppress proteinuria and morphological changes in the rat glomerulonephritis model induced by mAb 1-22-3.

Saponins from the root of Bupleurum falcatum

Three new saponins and nine known saponins were isolated from the dried roots of Bupleurum falcatum. On the basis of chemical and spectral analyses, the structures of new compounds, named 4''-O-acetylsaikosaponin d and hydroxysaikosaponins a and c, were established. In aqueous acidic conditions, saikosaponins a and d were converted into not only known compounds, saikosaponins b1 and b2, but also hydroxysaikosaponins a and d, respectively. Furthermore, quantitative analysis of the decoction of Bupleuri Radix itself by HPLC exhibited that it contained saikosaponins a, c and d, and hydroxysaikosaponins a, c and d.

Cell type-oriented differential modulatory actions of saikosaponin-d on growth responses and DNA fragmentation of lymphocytes triggered by receptor-mediated and receptor-bypassed pathways

We examined the immunoregulatory action of saikosaponin-d (SSd), which was isolated from the root of Bupleurum talcatum L. and had a steroid-like structure, on murine thymocytes, and compared the action with that on spleen cells. Constitutive DNA synthesis or the growth response stimulated with anti-CD3mAb of thymocytes were down-regulated by 3 micrograms/ml SSd, whereas with spleen cells these were up-regulated by the same concentration of SSd. On the other hand, 3 micrograms/ml of SSd greatly up-regulated the growth response and interleukin 2 (IL-2)/interleukin 4 (IL-4) production induced through a receptor-bypassed pathway by calcium ionophore A23187 plus phorbol 12-myristate 13-acetate (PMA) in thymocytes, whereas it only slightly up-regulated them in spleen cells. Moreover, the same concentration of SSd inhibited DNA fragmentation in thymocytes induced by A23187 or PMA. These results suggest a unique cell type-dependent immuno-modulatory action of SSd.