Dossier: Immunity and medical pathologies
Immunomodulatory effects of agents of plant origin

https://doi.org/10.1016/S0753-3322(03)00095-7Get rights and content

Abstract

The immunomodulatory properties of amla (Emblica officinalis) and shankhpushpi (Evolvulus alsinoides) were evaluated in adjuvant induced arthritic (AIA) rat model. Injecting Complete Freund’s Adjuvant (CFA) in right hind paw of the animals induced inflammation. The crude extracts of both the herbs were administered intraperitonially following a repeated treatment profile. The anti-inflammatory response of both the extracts was determined by lymphocyte proliferation activity and histopathological severity of synovial hyperplasia. Both the extracts showed a marked reduction in inflammation and edema. At cellular level immunosuppression occurred during the early phase of the disease. There was mild synovial hyperplasia and infiltration of few mononuclear cells in amla or shankhpushpi treated animals. The induction of nitric oxide synthase (NOS) was significantly decreased in treated animals as compared to controls. These observations suggest that both the herbal extracts caused immunosuppression in AIA rats, indicating that they may provide an alternative approach to the treatment of arthritis.

Introduction

Immunomodulation using medicinal plants can provide an alternative to conventional chemotherapy for a variety of diseases, especially when host defense mechanism has to be activated under the conditions of impaired immune response or when a selective immunosuppression is desired in situations like autoimmune disorders. Fruits of Emblica officinalis (family Euphorbiaceae) commonly known as “amla” or the Indian gooseberry, member of a small genus Emblica, are claimed to have anti-fungal, anti-bacterial, anti-diabetic, anti-clastogenic and hepatoprotective properties [7], [10] besides having significant anti-oxidant [4], adaptogenic [15] and anti-tumor activities [11]. Amla fruit has also been demonstrated to possess cytoprotective properties in acute cadmium toxicity [12]. Recent in vitro studies have also demonstrated that fruit extract of amla is able to relieve the immunosuppressive effects of chromium in rat lymphocytes [16]. Similarly, the whole plant of shankhpushpi, Evolvulus alsinoides (family Convolvulaceae) has been extensively used in ayurvedic practices as an alternative, antiphlogistic, febrifuge and as a brain tonic [14] to treat nervous debility and scrofula [3]. The juice of shankhpushpi has also been found to promote the healing of ulcers [2], and the leaf extract has been used to treat whitlow in the fingers and toes [3]. These effects of amla and shankhpushpi may be due to the presence of immunomodulatory activity in these plants. Despite many therapeutic effects of amla and shankhpushpi, there is a paucity of information on the immunomodulatory effects of these plants as anti-inflammatory agents. Therefore, the present study has been undertaken to determine the immunomodulatory effects of amla and shankhpushpi extracts in adjuvant induced arthritic (AIA) rat model. AIA is an erosive autoimmune polyarthritis involving both humoral and cell mediated immune responses that resemble human rheumatoid arthritis (RA).

Section snippets

Plant extracts

Fruits of amla and whole plant of shankhpushpi were collected from authentic sources, dried under shade and powdered in the laboratory. Crude powder of both the herbs were soaked in water over night, centrifuged at 3000 rpm and the supernatant was used for immunomodulatory studies.

Animals

The study was approved by Institute’s animal ethical committee and confirmed to national guidelines on the care and use of laboratory animals. Both male and female albino rats (Sprauge Dawley Strain), 10–12 weeks old,

Clinical analysis

All the animals injected with CFA developed severe inflammation within 24 h. In HE treated animals edema began to subside gradually and showed a significant reduction (P < 0.01) in swelling of joints and progression of inflammation as compared to untreated animals (Fig. 1). The reduction in swelling in HE treated groups was at par with dexamethasone treated animals. After 17 days of treatment, the swelling in treated animals was reduced almost equal to normal controls, whereas it persisted

Discussion

Results from the present study demonstrate that amla and shankhpushpi have a significant anti-inflammatory activity in AIA animals. There was a significant reduction in swelling and redness of inflamed areas in treated animals than in untreated controls. The ability of both the HEs to suppress the lymphocyte proliferation in response to AIA is consistent with the findings of earlier studies on the effect of commercially available drugs or cytokines or herbal preparations [5], [9], [13], [19].

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