Effect of Hypothalamic Proline-Rich Peptide (PRP-1) on Neuronal and Bone Marrow Cell Apoptosis

Chinese herbal formula, modified Guilu Erxian glue, alleviates apoptosis of hematopoietic stem cells by regulating SLAM-SAP signal pathway in aplastic anemia mice model

ETHNOPHARMACOLOGICAL RELEVANCE

Guilu Erxian Glue (GEG) and Danggui Buxue Tang (DBT) are traditional Chinese herbal formulas. According to the theory of traditional Chinese medicine, the combination of those two formulas (Modified Guilu Erxian Glue, MGEG) has the effects of tonifying the kidney and producing blood, was usually used to treat bone marrow failure diseases, including aplastic anemia (AA).

AIM OF THE STUDY

T lymphocytes play a crucial role in the disease pathogenesis and progression of AA. Our preliminary results confirmed that GEG can improve the damage of hematopoietic stem cells in mice, while DBT can reduce the proliferation and differentiation of T lymphocytes and inhibit the production of IFN-γ. We hypothesized that the combination of those two herbal formulas could inhibit immune attack and restore hematopoietic function through multiple mechanisms. In this study, we aim to study the curative effect of MGEG on regulating the expression of Signal lymphocyte activating molecule (SLAM), an activation-related molecule in T lymphocytes, thereby suppressing the immune function of T cells and decelerating the damage to hematopoietic stem cells.

MATERIALS AND METHODS

High-performance liquid chromatography-electrospray ionization/mass spectrometry system was used to identify the components of the MGEG formulation. Induction of aplastic anemia mouse model by injecting allogeneic lymphocyte suspension into BABL/c mice after ionizing radiation. Cyclosporine A (CsA) was used as a positive control drug. Flow cytometry was used to detect the number and apoptosis rate of hematopoietic stem cells in the bone marrow. Enzyme-linked immunosorbent assay was performed to measure the levels of IFN-γ and TNF-α. Immunofluorescence staining was used to assess the expression of T-bet and SLAM-SAP. Western Blot was conducted to examine the expression of activation-related molecules in T lymphocytes and proteins related to the Fas signal pathway. Hematoxylin-eosin staining was performed to observe pathological changes in the bone marrow tissue. Wright-Giemsa staining was utilized to evaluate alterations in the cellular composition and basic structure of the bone marrow cells (BMCs). Transmission electron microscopy was employed to observe changes in the structure and morphology of hematopoietic stem cells. The hematology analyzer was used to detect peripheral blood parameters.

RESULTS

Twenty-three different components were identified in MGEG. After MGEG treatment, the expression levels of Fyn and SLAM-SAP binding were increased in AA mice, while the expression levels of T-bet were decreased and the secretion of IFN-γ was reduced significantly. Additionally, MGEG also could downregulate the protein levels of Fas, caspase-3, and cleaved caspase-3 in AA mice.

CONCLUSION

MGEG could attenuate the production of IFN-γ by promoting the SLAM-SAP signal pathway to regulate the generation and distribution of T-bet in T cells. Additionally, it suppresses apoptosis of HSCs through intervention in the Fas-dependent pathway, thereby mitigating immune-mediated damage to HSCs.

Concepts of neuroendocrine cardiology and neuroendocrine immunology, chemistry and biology of signal molecules

Discovery of neurosecretion of cardioactive neurohormones produced by hypothalamic nuclei (NSO and NPV), as well as the biosynthesis of several immunomodulators (signal molecules of the neuroendocrine immune system of brain), deciphering of their chemical structure and study of their biological properties led to the foundation of two important trends of neurobiology: neuroendocrine immunology and cardiology. Hormone formation by atrium ganglionary nerve cells and auriculum establishment of neurohumoral interactions between hypothalamic and atrium neurosecretion indicated the existence of the system neuroendocrine hypothalamus--endocrine heart. Study of their biological properties promoted creation of powerful neurohormonal preparations for the treatment of immune, cardio-vascular, neurodegenerative, infectious and tumor diseases. Concepts suggested by us on neuroendocrine cardiology and immunology, create large perspectives for development of the theory and its implementation in medicine.

Hypothalamic proline rich polypeptide regulates hematopoiesis

The AGAPEPAEPAQPGVY proline-rich polypeptide (PRP-1) was isolated from neurosecretory granules of the bovine neurohypophysis; it is produced by N. supraopticus and N. paraventricularis. It has been shown that PRP-1 has many potentially beneficial biological effects including immunoregulatory, hematopoietic, antimicrobial and anti-neurodegenerative properties. Here we demonstrated that PRP-1 administration influence on redistribution of monocytes, granulocytes and lymphocytes between bone marrow (BM) and peripheral blood and promotes the influx of granulocytes and monocytes/macrophages from BM into peripheral blood and accumulation of immature granulocyte and monocyte in BM and delayed the maturation of T cells in BM. PRP-1 increased colony-forming cell proliferation in rat cells in vivo. In PRP-treated rat BM, the CFU number at day 4, 7 and 14 was considerably increased in comparison with untreated rats BM and no difference was found at day 21 and day 28. We found that PRP-1 enhances erythroid and myeloid colonies formation in human CD34(+) progenitor cell culture in the presence of different growth factors and down-regulates T cells colony formation and specific surface markers expression during induction of human CD34(+) progenitor cells differentiation into T lymphocytes lineage. We suggested that the hypothalamic PRP-1 possibly represents an endogenous peptide whose primary functions are to regulate neuronal survival and differentiation and hematopoiesis within neurosecretory hypothalamus-bone marrow humoral axis.

Neuroprotection by hypothalamic peptide proline-rich peptide-1 in Abeta25-35 model of Alzheimer's disease

BACKGROUND

This work sought to determine the effects of hypothalamic proline-rich peptide (PRP)-1 in a rat model of Alzheimer's disease.

METHODS

Complex histochemical, electrophysiologic, and behavioral analyses were performed on intact or diseased Wistar rats (n = 28). Pathologic conditions were induced by bilateral intracerebroventricular injection of amyloid peptide Abeta25-35. The diseased rats received systemic administration of PRP-1 or placebo control.

RESULTS

Abeta25-35 caused cellular neurodegeneration with marked glial reaction in the hippocampal complex and almost full destruction of the dentate fascia, which was not observed in conditions of PRP-1 administration after Abeta25-35 injection. Hippocampal neurons of intact animals responded to high-frequency (tetanic) stimulation of entorhinal cortex of ipsilateral cerebral hemisphere by tetanic and posttetanic potentiation of a different intensity and duration, which was accompanied by posttetanic depression. Abeta25-35 led to significant changes in the level and pattern of hippocampal neuronal activity, indicating the absence of both tetanic and posttetanic activity. Poststimulus activity manifestations rarely occurred and rapidly decreased after repeated trials. This indicated the focal character of lesion. Regular administration of PRP-1 for 4 weeks resulted in optimal restoration of electrophysiologic parameters. PRP-1 maintained the initial learning level achieved in a behavioral study in a Morris water maze.

CONCLUSIONS

Systemic administration of PRP-1 possesses neuroprotective effects and can prevent the neurodegeneration in hippocampus induced by Abeta25-35. This suggests that PRP-1 could be a potential therapeutic agent for specific neurodegenerative diseases.