Inhibition of antigen specific lymphocyte proliferation and cytokine stimulation by peptidomimetic opioid compound

Naloxone Diminishes the Virulence and Modifies the Cellular Immune Responses of BALB/c Mice Infected with Leishmania major

PURPOSE

Leishmania major-infected BALB/c mice display strong susceptibility to the infection due to the induction of Th2 response. The aim of this study was to assess the effects of naloxone on virulence of L. major in BALB/c mice and the ensued cellular immune response.

METHODS

The effects of injection of a single dose of naloxone in the footpad of L. major-infected BALB/c mice were investigated by evaluating the lesion sizes, the parasite burden, cell proliferation, secreted cytokines (IFN-γ, IL-4, IL-10 and IL-12) and their genes expressions due to naloxone treatment while the untreated mice were used as a control.

RESULTS

Significantly lower lesion sizes and less parasite burden were measured in the treated mice. Significantly decreased productions of IFN-γ, IL-12, IL-4, and IL-10 were also observed in the treated mice at week 4 post-infection while the production IL-10 remained significantly hindered till 8 weeks post-infection.

CONCLUSION

Our data indicated that although the treatment of L. major-infected BALB/c mice with a single dose of naloxone was unable to improve the cellular immune response, it led to lower virulence, confirmed by significantly reduced lesions and parasite load.

Human S-antigen: peptide determinant recognition in uveitis patients

Uveitis is an inflammation of the uveal tract and is one of the major causes of visual impairment. Several lines of evidence suggest an important role for activated T lymphocytes in the perpetuation of posterior uveitis. In sequel to our preliminary observations with human S-antigen, we have further investigated the proliferative response of peripheral blood lymphocytes of posterior uveitis patients against 20 linear and 9 overlapping peptides of retinal S-antigen. The expression of surface markers CD4, CD8, CD29, CD45RA in peripheral blood was detected by flow cytometry. We have also assessed the pattern of cytokines present in peripheral blood mononuclear cells (PBMCs) using ribonuclease protection assay (RPA). Nineteen out of 32 patients' lymphocytes showed proliferative response to S-antigen, one or more of its 20 linear and nine overlapping synthetic peptides. Six patients showed significant lymphoproliferative response against various peptides. The maximum response was found to peptides from the 231-270 amino acid region of human S-antigen sequence. The percentage of CD29(+) (memory cells) and CD45RA(+) (naive cells) T-lymphocytes was higher in patients compared to healthy volunteers. There was a demonstrable difference in the percentage of CD4(+) and CD8(+) lymphocytes in the patients (P <== 0.05) as compared to controls. Higher message for interleukin (IL)-5, IL-10, IL-15, IL-9, IL-2, IL-13, and interferon (IFN)-gamma was observed in uveitis patients than in healthy individuals. In brief, our study suggests that a particular region of S-antigen plays an important role in idiopathic uveitis.

Immunomodulation by peptide analogs of retroviral envelope protein

The mechanism by which retroviral proteins exert their immunosuppressive influence has remained enigmatic. Early studies have demonstrated that retroviral infection suppresses cellular and humoral immune responses. A hydrophilic 26 amino acid region of the otherwise hydrophobic transmembrane envelope protein of murine and feline leukemia viruses, p15E, is conserved among the transmembrane envelope proteins of numerous animal retroviruses (e.g. murine, feline, bovine and simian) as well as in human T-cell leukemia virus, and to a lesser extent, in human immunodeficiency virus (HIV). We evaluated the immunomodulatory properties of various synthetic retroviral envelope peptides synthesized as overlapping fragments to this conserved sequence. We report that two small peptides inhibit human mixed lymphocyte reaction (MLR), interleukin-2 (IL-2) and tumor necrosis factor (TNF-alpha) production. These peptides did not affect human natural killer (NK) cell cytotoxicity in vitro, and nitric oxide (NO) production in mouse macrophage cells, RAW264.7. Our observations suggests immunomodulatory potential of two retroviral peptide analogs.

Inhibition of anti-CD3 and interleukin-2 stimulated T lymphocyte proliferation by peptidomimetic opioid compound

In continuation to our earlier studies with peptidomimetic opioid compounds, we have further investigated immunosuppressive properties of one of our peptidomimetic compound (Tyr-NH-CH2-CH2-O-Phe-NH2) using peripheral blood mononuclear cells (PBMCs) of healthy volunteers. Peptidomimetic compound was evaluated for its effect on anti-CD3 and recombinant human interleukin-2 (rhIL-2) stimulated lymphocyte proliferation in vitro and lipopolysaccharide (LPS) induced activation of mitogen activated protein kinase (MAPK, pp42/44) in mouse macrophage cells (RAW 264.7). Our results show the immunosuppressive potential of synthetic peptidomimetic compound. This compound significantly inhibited anti-CD3 and rhIL-2 stimulated lymphocyte proliferation in vitro. However, this peptidomimetic compound did not show any effect on LPS induced MAPK activation. These observations suggest that above peptidomimetic compound has potential to inhibit immune responses mediated by lymphocytes.

Anticellular and immunosuppressive properties of ethanolic extract of Acorus calamus rhizome

Modulation of immune response to alleviate disease has been of interest since long. Plant extracts have been widely investigated for possible immunomodulatory properties. We have evaluated the anticellular and immunomodulatory properties of ethanolic extract of Acorus calamus rhizome. This extract inhibited proliferation of mitogen (phytohaemagglutinin; PHA) and antigen (purified protein derivative; PPD)-stimulated human peripheral blood mononuclear cells (PBMCs). In addition, A. calamus extract inhibited growth of several cell lines of mouse and human origin. It also inhibited production of nitric oxide (NO), interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha). Intracytoplasmic interferon-gamma (IFN-gamma) and expression of cell surface markers, CD16 and HLA-DR, on human PBMC, were not affected on treatment with A. calamus extract but CD25 expression was down regulated. Our study demonstrates the antiproliferative and immunosuppressive potential of ethanolic extract of A. calamus rhizome in vitro.