Immunomodulatory effect of Tylophora indica on Con A induced lymphoproliferation

Our preliminary studies with tylophora alkaloids had shown that they inhibit cellular immune responses like contact sensitivity to dinitro-flurobenzene and delayed hypersensitivity to sheep red blood cells, in vivo. Investigations were hence carried out to determine the cellular targets of tylophora alkaloids in in vitro systems. Con A induced proliferation of splenocytes was used as a model system to study the effect of the alkaloids on cellular immune responses. The alkaloid mixture was found to inhibit proliferation of splenocytes at higher concentrations and augment the same at lower concentrations. Both macrophages and T cells were found to be vulnerable to tylophora alkaloids. The alkaloid mixture suppressed IL-2 production in Con A stimulated splenocytes at the inhibitory or higher concentrations and enhanced production at the lower concentrations. IL-1 production by activated macrophages on the contrary was doubled in the presence of inhibitory concentrations of tylophora. These studies indicate that tylophora alkaloids have a concentration dependent biphasic effect on Con A induced mitogenesis. At lower concentrations they augment Con A induced lymphoproliferation by enhancing IL-2 production. Inhibition of proliferation at higher concentrations of the alkaloid is due to inhibition of IL-2 production and activation of macrophages, which have a cytostatic effect.     

Inhibition of cellular immune responses by Tylophora indica in experimental models.

Tylophora alkaloids have been shown to have antiasthmatic, antiinflammatory and antianaphylactic properties. Since all these disorders are a consequence of altered immunological status, the effect of these alkaloids on model immune reactions were studied. Crude extract of the leaves of Tylophora indica inhibited delayed hypersensitivity reaction to sheep red blood cells in rats when the alkaloid mixture was administered before and after immunization with these cells. The alkaloid mixture also inhibited contact sensitivity to dinitro-fluorobenzene in mice when given prior to or after contact sensitization. Lymphocytes taken from contact sensitized mice, when treated with tylophora alkaloid in vitro and transferred into naive syngeneic hosts, could suppress the transfer of delayed type hypersensitivity (DTH) response. However, the tylophora alkaloids could not suppress primary humoral (IgM) immune response to SRBC in mice at the same dose. These studies suggest that tylophora alkaloids suppress cellular immune responses when administered at any stage during the immune response.     

Immunomodulatory role of 1,25-dihydroxyvitamin D3.

The active vitamin D metabolite 1,25-dihydroxyvitamin D3 [1,25-D3] is thought to promote many of its actions through interaction with a specific intracellular receptor. The discovery of such receptors in monocytes and activated lymphocytes has led investigators to evaluate the role of the hormone on the immune system. The sterol inhibits lymphocyte proliferation and immunoglobulin production in a dose-dependent fashion. At a molecular level, 1,25-D3 inhibits the accumulation of mRNA for IL-2, IFN-gamma, and GM-CSF. At a cellular level, the hormone interferes with T helper cell (Th) function, reducing Th-induction of immunoglobulin production by B cells and inhibiting the passive transfer of cellular immunity by Th-clones in vivo. The sterol promotes suppressor cell activity and inhibits the generation of cytotoxic and NK cells. Class II antigen expression on lymphocytes and monocytes is also affected by the hormone. When given in vivo, 1,25-D3 has been particularly effective in the prevention of autoimmune diseases such as experimental autoimmune encephalomyelitis and murine lupus but its efficacy has been limited by its hypercalcemic effect. Synthetic vitamin D3 analogues showing excellent 1,25-D3-receptor binding but less pronounced hypercalcemic effects in vivo have recently enhanced the immunosuppressive properties of the hormone in autoimmunity and transplantation.     

Effects of ascorbic acid on axillary shoot induction in Tylophora indica (Burm. f.) Merrill.

A procedure for rapid in vitro multiplication of Tylophora indica (Burm. f.) Merrill., an important indigenous medicinal plant, has been developed. Addition of ascorbic acid was essential to induce sprouting of axillary buds. Optimum multiplication was observed on MS medium containing 6-benzylamino purine (5.0 mg l^–1), -naphathalene-acetic acid (0.5 mg l^–1) and ascorbic acid (100 mg l^–1). Rooting of in vitro produced shoots was readily achieved with indole-3-acetic acid alone (1.0 mg l^–1) in MS. The plantlets thus obtained were successfully transferred to pots in large numbers which grew normally.Abbreviations BAP 6-benzylamino purine - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - 2ip 2-isopentenyladenine - Kn kinetin - MS Murashige & Skoog media - NAA -naphthalene acetic acid     

Immunomodulatory effect of Moringa oleifera Lam. extract on cyclophosphamide induced toxicity in mice

Immunomodulatory effect of ethanolic extract (50%) of M. oleifera leaves (MOE) has been studied in normal and immunosuppressed mice models. Different doses of MOE i.e. 125, 250 and 500 mg/kg body weight of mice were administered orally for 15 days. Cyclophosphamide at a dose of 30 mg/kg body weight was administered orally for the next 3 days. On day 16 and 19, hematological parameters like white blood cell (WBC) count, red blood cell (RBC) count, haemoglobin level (Hb), percent neutrophils and organ weight were recorded. Effect of MOE on phagocytic activity of mice macrophages was determined by carbon clearance test. MOE showed significant dose dependent increase in WBC, percent neutrophils, weight of thymus and spleen along with phagocytic index in normal and immunosuppressed mice. The results indicate that MOE significantly reduced cyclophosphamide induced immunosuppression by stimulating both cellular and humoral immunity.     

Immunomodulatory effect of resistin in human dendritic cells stimulated with lipoteichoic acid from Staphylococcus aureus

Resistin is an adipokine whose physiologic role in obesity, type II diabetes mellitus, and inflammatory diseases has been a subject of debate because while it is expressed in adipocytes and adipose tissue in mouse, it is expressed in leukocytes, such as macrophages, in human. In the present study, we attempt to define the effect of resistin on human dendritic cells (DCs) derived from CD14⁺ monocytes. When DCs were stimulated with lipoteichoic acid (LTA) and treated with various concentrations of resistin, antigen-uptake process and the endocytic capacity of DCs were decreased. It is intriguing that resistin attenuated cytokine production in LTA-primed DCs. Consequently, T cell activity was reduced when lymphocytes were mixed with Staphylococcus aureus-primed autologous DCs treated with resistin compared to S. aureus-primed DCs without resistin. Our results suggest that resistin interferes with the efficacy of immune responses activated by Gram-positive bacterial infection in human DCs.     

Immunomodulatory effect of laser on whole body exposure.

All biomedical laser applications are based on the interaction of laser light with biological system. During the past decade considerable evidence has accumulated demonstrating that non-thermal exposure to laser can elicit cellular changes in the immune system. In the present study, we have analyzed the effect of laser on immune response in rats. A group of rats were exposed to 0.225 mu j/cm2 for 90 min for 3 days in specially designed fiberglass chambers. The whole body exposure of rats of He-Ne laser modulated both the humoral and cellular responses to tetanus toxoid stimulation. Plain red light used as a control for red laser light showed an appreciable degree of response as compared to the control groups, but not to the extent of the response to laser. Non-responders turned responders after exposure to laser. There was no response in unimmunized groups when exposed to laser and red light alone. The early and heightened immune response and proliferation of lymphocytes after exposure to laser is suggestive of a complex interaction at the cellular immune response level.     

糖、GA3及ABA对印度娃儿藤(Tylophora indica(Burm.f.)Merrill)体细胞胚发生的影响

从印度娃儿藤节间外植体获取愈伤组织,分析了糖、赤霉素(GA3)及脱落酸(ABA)对愈伤组织形成体细胞的影响。实验证明,含4μmol/L2,4-二氯苯氧乙酸(2,4-D)的MS培养基是获得具有成胚功能的愈伤组织的最佳培养基。在含有6μmol/L激动素(Kn)的MS培养基上,高达69%的愈伤组织分化为体细胞胚,平均单位外植体(每克愈伤组织)产胚25个。在6μmol/LKn存在的条件下,分析了蔗糖、葡糖糖对胚产生的影响,不同的糖及不同糖浓度对体细胞胚的发生影响很大。6μmol/L Kn与200mmol/L蔗糖处理胚胎发生率最大(71%),单位外植体生成49个胚。然而葡萄糖与Kn、或者葡糖糖、蔗糖与Kn三者加在一起则降低成胚率及产胚数。一定浓度的GA3和ABA能促进体细胞胚的产生。在含200mmol/L蔗糖的培养基中加10μmol/LGA3胚的生成率为98%,单位外植体产胚51个。在含200mmol/L蔗糖的培养基中加2μmol/L ABA能显著增加体细胞胚的量,该培养基上每外植体平均生成44个胚,产率为95%。本研究显示,含200mmol/L蔗糖的培养基中分别加入6μmol/L Kn、10μmol/L GA3或者2μmol/L ABA能显著提高印度娃儿藤体细胞胚发生率,而单独的葡萄糖或葡糖糖和蔗糖则有抑制作用。得到的胚均能正常发育并分化为植株。     

Plant regeneration through somatic embryogenesis and rapd analysis of regenerated plants in Tylophora indica (Burm. F. Merrill.)

Summary A procedure for the regeneration of complete plantlets of Tylophora indica from cultured leaf callus via somatic embryogenesis is described. Callus induction from leaf explants was on Murashige and Skoog (MS) medium with different concentrations of 2,4-dichlorophenoxyacetic acid (2.4-D; 0.03–3 mg l⁻¹; 0.0–13.56 μM) and kinetin (Kn; 0.01 mg l⁻¹; 0.05 μM). The best response for callus induction was obtained on MS medium containing 2 mg l⁻¹ (9.04 μM) 2.4-D and 0.01 mg l⁻¹ (0.05 μM) Kn. After two subeultures on the same medium the embryogenic callus was transferred to MS medium with different concentrations of the cytokinin, 6-benzyladenine (0.5–3 mg l⁻¹; 2.22–13.32 μM) and 2-isopentenyladenine (2ip; 0.53 mg l⁻¹; 2.46–14.76 μM) along with 0.01 mg l⁻¹ (0.05 μM) indole-3-butyric acid (IBA) for somatic embryo development and maturation. MS medium with 2 mg l⁻¹ (9.84 μM) 2ip produced the maximum number of mature somatic embryos. The mature embryos were bipolar and on transfer to MS basal medium produced complete plantlets. After hardening the regenerants were planted in the Gudalur forests of Western Ghats. Total DNA was extracted from 14 regenerants and the mother plant. Random amplified polymorphic, DNA (RAPD) analysis was carried out using 20 arbitrary oligonucleotides. The amplification products were monomorphic among all the plants revealing the genetic homogeneity and true-to-type nature of the regenerants.     

Effect of sodium diethyl dithiocarbamate on mitogen induced lymphoproliferation in vitro

Sodium diethyl dithiocarbamate (DTC) is a low molecular weight sulphur compound which has been shown to be an adjuvant of immunity in vivo. In this report, DTC was shown to inhibit in vitro DNA-synthesis of human peripheral blood lymphocytes stimulated by phytohemagglutinin or concanavalin A. DTC could act directly at the cellular level and indirectly by interfering with culture medium or lectins.     

Immunomodulatory effect of human umbilical cord Wharton's jelly-derived mesenchymal stem cells on lymphocytes

Studies have shown that mesenchymal stem cells (MSCs) have low immunogenicity and immune regulation. Human umbilical cord Wharton’s jelly provides a new source for MSCs that are highly proliferative and have multi-differentiation potential. To investigate immunomodulatory effects of human Wharton’s jelly cells (WJCs) on lymphocytes, we successfully isolated MSCs from human umbilical cord Wharton’s jelly. WJCs expressed MSC markers but low levels of human leukocyte antigen (HLA)-ABC and no HLA-DR. These results indicate that WJCs have low immunogenicity. Both WJCs and their culture supernatant could inhibit the proliferation of phytohemagglutinin-stimulated human peripheral blood lymphocytes and mouse splenocytes. Additionally, WJCs suppressed secretion of transforming growth factor-β1 and interferon-γ by human peripheral blood lymphocytes. We conclude that the immunomodulatory effect of WJCs may be related to direct cell contact and inhibition of cytokine secretion by human peripheral blood lymphocytes.     

Immunomodulatory activity of polyphenols derived from Cassia auriculata flowers in aged rats

The immunomodulatory activity of Cassia auriculata (CA)-derived polyphenols was tested on aged rats. Rats (24–26 months old) were given CA polyphenols supplementation at doses of 25, 50, and 100 mg/kg for 28 days. Flow cytometry analysis of CA polyphenols-treated aged rats showed increased T and B cells percentage along with enhanced proliferation of splenocytes in both resting and LPS-stimulated cells. Increased percentage of pan T cells is further supported by an elevation of CD4+, CD8+, and CD4+CD25+ regulatory cells. In terms of innate immune cell activity, CA polyphenol supplementation reduced the oxidative burst activity of neutrophils in response to PMA and Escherichia coli activation. Our results collectively show that polyphenols derived from CA boost T cell immunity by increasing the number of T cells and its sensitivity towards stimulants and decreasing ROS production by neutrophils that could potentially harm multiple biological systems in aged individuals.     

Age-related effect induced by oxidative stress on the cerebral glutathione system

In the forebrain from male Wistar rats aged 5, 15 and 25 months, age-related putative alterations in the glutathione system (reduced and oxidized glutathione; redox index) were chronically induced by the administration in drinking water of free radical generators (hydrogen peroxide, ferrous chloride) or of inhibitors of endogenous free radical defenses (diethyl-dithio-carbamate, an inhibitor of superoxide dismutase activity). In hydrogen peroxide administered rats, both reduced glutathione and the cerebral glutathione redox index markedly declined as a function of aging, whereas oxidized glutathione consistently increased. In contrast, chronic iron intake failed to modify the reduced glutathione in forebrain from the rats of the different ages tested, whereas the oxidized glutathione was increased in the older brains. The chronic intake of diethyl-dithio-carbamate enhanced the concentrations of reduced glutathione in the forebrains from the rats of the different ages tested, the oxidized glutathione being unchanged. In 15-month-old rats submitted to chronic oxidative stress, ergot alkaloids (and particularly dihydroergocriptine) interfered with cerebral glutathione system, while papaverine was always ineffective. The comprehensive analysis of the data indicates that: (a) both the type of oxidative stress and the age of the animals modulate the cerebral responsiveness to the putative modifiers in the level of tissue free radicals; (b) aging magnifies the cerebral alterations induced by oxidative stress; the (c) cerebral glutathione system may be modified by metabolic rather than by circulatory interferences; (d) a balance between the various cerebral antioxidant defenses is present, the perturbation of an antioxidant system resulting in the compensatory modified activity of component(s) of another system.     

Immunomodulatory properties of human adult and fetal multipotent mesenchymal stem cells

In recent years, a large number of studies have contributed to our understanding of the immunomodulatory mechanisms used by multipotent mesenchymal stem cells (MSCs). Initially isolated from the bone marrow (BM), MSCs have been found in many tissues but the strong immunomodulatory properties are best studied in BM MSCs. The immunomodulatory effects of BM MSCs are wide, extending to T lymphocytes and dendritic cells, and are therapeutically useful for treatment of immune-related diseases including graft-versus-host disease as well as possibly autoimmune diseases. However, BM MSCs are very rare cells and require an invasive procedure for procurement. Recently, MSCs have also been found in fetal-stage embryo-proper and extra-embryonic tissues, and these human fetal MSCs (F-MSCs) have a higher proliferative profile, and are capable of multilineage differentiation as well as exert strong immunomodulatory effects. As such, these F-MSCs can be viewed as alternative sources of MSCs. We review here the current understanding of the mechanisms behind the immunomodulatory properties of BM MSCs and F-MSCs. An increase in our understanding of MSC suppressor mechanisms will offer insights for prevalent clinical use of these versatile adult stem cells in the near future.     

Immunological properties of Fc receptor on lymphocytes. 4. Fc receptor of Con A induced suppressor and helper T cells.

The effects of a variety of exposure regimens were assessed for their ability to induce optimal, immunologically mediated resistance against subsequent homologous reinfection by Schistosoma mansoni. Following exposure, Fischer rats modulated their subsequent worm burden, through as yet undefined internal mechanisms, and in a manner which resulted ultimately in a relatively consistent worm burden. The magnitude and rapidity of development and the longevity of maintenance of resistance was related to the intensity and pattern of exposure to normal cercariae. The modulatory effects tended to favor the development of optimal resistance over a wide variety of exposure patterns. Optimal resistance was most efficiently stimulated and maintained by immunogens which were associated with early stages of infection. Antihelminthic drug therapy adversely affected both the development and maintenance of resistance. Rats were also exposed to irradiated cercariae and soluble surface membrane preparations obtained from cercariae, adult worms, or eggs. Animals exposed to irradiated cercariae or soluble cercarial immunogen developed resistance to approximately 80 and 35%, respectively, of the levels shown by the naturally infected animals. The mechanism of this variable resistance was investigated using a number of in vivo and in vitro assessments and is the subject of a subsequent report.