Adjuvant effect of aqueous extract ofRhodiola imbricatarhizome on the immune responses to tetanus toxoid and ovalbumin in rats

Modulatory effects of feeding pregnant and lactating mice Rhodiola kirilowii extracts on the immune system of offspring

Plants of Rhodiola genus are medicinal herbs that have a number of therapeutic properties, including anti-inflammatory and immunomodulatory activity. The present study aimed to determine whether the use Rhodiola kirilowii as an immunostimulant during pregnancy has an adverse effect on the development of the offspring immune system. Following mating, pregnant mice were placed in three groups that were fed during pregnancy and lactation with R. kirilowii aqueous extract (RKW; 20 mg/kg), R. kirilowii 50% hydro-alcoholic extract (RKW-A; 20 mg/kg) or water (control group), receiving water. Following birth, offspring were given six weeks to develop prior to evaluation of their immune system. Morphometric and morphological examination of the spleen did not reveal any abnormalities or differences between the experimental and control groups. However, both RKW and RKW-A splenic lymphocytes presented a diminished proliferative response to concanavalin A. RKW spleen lymphocytes demonstrated increased metabolic activity following phytohaemagglutinin (PHA) stimulation, which was associated with a higher percentage of cluster of differentiation 4 positive spleen cells and lower interleukin-17a (IL-17a) serum concentration. The RKW-A group exhibited a diminished proliferative response of spleen lymphocytes to PHA and lipopolysaccharide (LPS), and increased serum concentrations of IL-10 and tumor necrosis factor-α (TNF-α). The progeny of mice fed with RKW-A extract demonstrated a significantly lower level of anti-SRBC antibody following immunization compared with progeny of the control (P=0.0305) and RKW (P=0.0331) groups. In conclusion, caution is recommended in the use of RKW and RKW-A extracts as immunostimulants in pregnancy.

Rhodiola plants: Chemistry and biological activity

Rhodiola is a genus of medicinal plants that originated in Asia and Europe and are used traditionally as adaptogens, antidepressants, and anti-inflammatory remedies. Rhodiola plants are rich in polyphenols, and salidroside and tyrosol are the primary bioactive marker compounds in the standardized extracts of Rhodiola rosea. This review article summarizes the bioactivities, including adaptogenic, antifatigue, antidepressant, antioxidant, anti-inflammatory, antinoception, and anticancer activities, and the modulation of immune function of Rhodiola plants and its two constituents, as well as their potential to prevent cardiovascular, neuronal, liver, and skin disorders.

Rhodiola inhibits dengue virus multiplication by inducing innate immune response genes RIG-I, MDA5 and ISG in human monocytes

Recognition of virus infection by retinoic acid-inducible gene (RIG) I and melanoma differentiation-associated protein (MDA) 5, which are RNA helicases, and interferon-stimulated gene (ISG) 15 activates cascades of signal transduction pathways leading to production of type I interferons and proinflammatory cytokines that orchestrate the elimination of the viruses. However, it has been demonstrated that RNA-helicase-mediated innate immunity plays an essential role in defending the host from infection. In our efforts to identify plant-derived antivirals that selectively enhance ISG- and RNA-helicase-mediated antiviral immune responses, we identified a plant, rhodiola, that significantly promoted ISG, RIG-I and MDA 5 gene expression and an antiviral immune response against dengue virus (DENV) infection. Rhodiola induced interferon (IFN) β and other cytokines, including IL-1β, TNF-α, IL-6 and IL-8, in infected cells. It was also found that rhodiola upregulated phosphorylated eIF-2α, PKR and NF-kB in infected cells. In addition, the number of NK cells was also increased by rhodiola treatment in dengue-virus-infected human PBMCs. Treatment with a crude extract of rhodiola (RAE) resulted in effects in the 20 % range, which is similar to the magnitude of the same effects observed in DENV infections. Taken together, our results imply that rhodiola induces pharmacological modulation of RIG-I, MDA 5 and ISG signal transduction pathways in favor of the induction of a beneficial antiviral immune response against dengue virus, which can be a novel therapeutic strategy for management of infection.

Changes of cytokines during a spaceflight analog--a 45-day head-down bed rest

Spaceflight is associated with deregulation in the immune system. Head-down bed rest (HDBR) at -6° is believed to be the most practical model for examining multi-system responses to microgravity in humans during spaceflight. In the present study, a 45-day HDBR was performed to investigate the alterations in human immune cell distributions and their functions in response to various stimuli. The effect of countermeasure, Rhodiola rosea (RR) treatment, was also examined. A significant decrease of interferon-γ (IFN-γ) and interleukin-17 (IL-17) productions by activated T cells, increase of IL-1β and IL-18 by activated B and myeloid cells were observed during HDBR. The upregulation of serum cortisol was correlated with the changes of IL-1 family cytokines. In addition, a significant increase of memory T and B cell and regulatory T cells (Treg) were also detected. The uptake of RR further decreased IFN-γ level and slowed down the upregulation of IL-1 family cytokines. These data suggest that for prolonged HDBR and spaceflight, the decreased protective T cell immunity and enhanced proinflammatory cytokines should be closely monitored. The treatment with RR may play an important role in suppressing proinflammatory cytokines but not in boosting protective T cell immunity.

The ocular conjunctiva as a mucosal immunization route: a profile of the immune response to the model antigen tetanus toxoid

Background

In a quest for a needle-free vaccine administration strategy, we evaluated the ocular conjunctiva as an alternative mucosal immunization route by profiling and comparing the local and systemic immune responses to the subcutaneous or conjunctival administration of tetanus toxoid (TTd), a model antigen.

Materials and methods

BALB/c and C57BL/6 mice were immunized either subcutaneously with TTd alone or via the conjunctiva with TTd alone, TTd mixed with 2% glycerol or TTd with merthiolate-inactivated whole-cell B. pertussis (wBP) as adjuvants. Mice were immunized on days 0, 7 and 14 via both routes, and an evaluation of the local and systemic immune responses was performed two weeks after the last immunization. Four weeks after the last immunization, the mice were challenged with a lethal dose (2 × LD₅₀) of tetanus toxin.

Results

The conjunctival application of TTd in BALB/c mice induced TTd-specific secretory IgA production and skewed the TTd-specific immune response toward a Th1/Th17 profile, as determined by the stimulation of IFNγ and IL-17A secretion and/or the concurrent pronounced reduction of IL-4 secretion, irrespective of the adjuvant. In conjunctivaly immunized C57BL/6 mice, only TTd administered with wBP promoted the establishment of a mixed Th1/Th17 TTd-specific immune response, whereas TTd alone or TTd in conjunction with glycerol initiated a dominant Th1 response against TTd. Immunization via the conjunctiva with TTd plus wBP adjuvant resulted in a 33% survival rate of challenged mice compared to a 0% survival rate in non-immunized animals (p<0.05).

Conclusion

Conjunctival immunization with TTd alone or with various adjuvants induced TTd-specific local and systemic immune responses, predominantly of the Th1 type. The strongest immune responses developed in mice that received TTd together with wBP, which implies that this alternative route might tailor the immune response to fight intracellular bacteria or viruses more effectively.

Chemometric profile of root extracts of Rhodiola imbricata Edgew. with hyphenated gas chromatography mass spectrometric technique

Rhodiola imbricata Edgew. (Rose root or Arctic root or Golden root or Shrolo), belonging to the family Crassulaceae, is an important food crop and medicinal plant in the Indian trans-Himalayan cold desert. Chemometric profile of the n-hexane, chloroform, dichloroethane, ethyl acetate, methanol, and 60% ethanol root extracts of R. imbricata were performed by hyphenated gas chromatography mass spectrometry (GC/MS) technique. GC/MS analysis was carried out using Thermo Finnigan PolarisQ Ion Trap GC/MS MS system comprising of an AS2000 liquid autosampler. Interpretation on mass spectrum of GC/MS was done using the NIST/EPA/NIH Mass Spectral Database, with NIST MS search program v.2.0g. Chemometric profile of root extracts revealed the presence of 63 phyto-chemotypes, among them, 1-pentacosanol; stigmast-5-en-3-ol, (3β,24S); 1-teracosanol; 1-henteracontanol; 17-pentatriacontene; 13-tetradecen-1-ol acetate; methyl tri-butyl ammonium chloride; bis(2-ethylhexyl) phthalate; 7,8-dimethylbenzocyclooctene; ethyl linoleate; 3-methoxy-5-methylphenol; hexadecanoic acid; camphor; 1,3-dimethoxybenzene; thujone; 1,3-benzenediol, 5-pentadecyl; benzenemethanol, 3-hydroxy, 5-methoxy; cholest-4-ene-3,6-dione; dodecanoic acid, 3-hydroxy; octadecane, 1-chloro; ethanone, 1-(4-hydroxyphenyl); α-tocopherol; ascaridole; campesterol; 1-dotriacontane; heptadecane, 9-hexyl were found to be present in major amount. Eventually, in the present study we have found phytosterols, terpenoids, fatty acids, fatty acid esters, alkyl halides, phenols, alcohols, ethers, alkanes, and alkenes as the major group of phyto-chemotypes in the different root extracts of R. imbricata. All these compounds identified by GC/MS analysis were further investigated for their biological activities and it was found that they possess a diverse range of positive pharmacological actions. In future, isolation of individual phyto-chemotypes and subjecting them to biological activity will definitely prove fruitful results in designing a novel drug.