Dipeptide gamma-d-Glu-d-Trp (thymodepressin) inhibits migration of CD34+ cells from the bone marrow into peripheral blood during tumor growth.

We studied the effect of dipeptide gamma-d-Glu-d-Trp (thymodepressin) on migration of CD34+ hemopoietic precursors and their direct adhesion to fibronectin in tumor-bearing mice on days 8, 11, 15, and 17 of tumor growth and on expression of CXCR-4 (CD184+) to SDF-1 and integrin beta1 (CD29+) by bone marrow cells. In tumor-bearing mice treated with gamma-d-Glu-d-Trp, the percent of CD34+ hemopoietic precursors in the peripheral blood considerably decreased throughout the observation period; the content of CD34+ hemopoietic precursors in the tumor tissue was 2-3-fold below the control against the background of increased content of CD34+ cells in the bone marrow. In animals treated with the peptide, the content of cells expressing CXCR-4 in the peripheral blood, bone marrow, and tumor tissue significantly decreased, while the percent of cells expressing integrin beta1 receptor (CD29+) in the bone marrow increased 2-fold, which was paralleled by an almost 2-fold increase in the percent of cells binding to fibronectin. We hypothesized that dipeptide gamma-d-Glu-d-Trp suppressed mobilization/migration of CD34+ hemopoietic precursor cells from the bone marrow to the peripheral blood of tumor-bearing mice.

The effects of the EW dipeptide optical and chemical isomers on the CFU-S population in intact and irradiated mice.

The influence of Glu-Trp (EW) synthetic dipeptide isomers on hemopoietic progenitor cells and certain immune response reactions is determined by their optical and chemical properties. Thus, the all L-amino acid containing dipeptides L-Glu-L-Trp and L-gammaGlu-L-Trp have no effect on proliferation of committed and pluripotent CFU-S in intact bone marrow. The optical isomers of the Glu residue are an essential determinant of the EW dipeptide biological activity. The inversion of the amino acid optical form imparts suppressor properties: D-Glu-D-Trp,D--gammaGlu-D-Trp, D-Glu-L-Trp and D-gammaGlu-L-Trp inhibit proliferation of hemopoietic progenitors in intact bone marrow. The type of the peptide bond between L-Glu and Trp is another important factor for the biological activity of the L-Glu-containing peptides. Unlike L-Glu-D-Trp with alpha-peptide bond, the dipeptide L-gammaGlu-D-Trp with gamma-peptide bond stimulates CFU-S-8 proliferation in intact bone marrow. The diverse effects of the EW optical isomers on hemopoietic progenitors underlie the radioprotective properties of the D-Glu-containing dipeptides and the radiotherapeutic ones of the L-Glu dipeptides. In animals, pre-irradiation injection of D-Glu-D-Trp, D-gammaGlu-D-Trp, D-Glu-L-Trp, D-gammaGlu-L-Trp, or post-irradiation injection of L-Glu-L-Trp, L-gammaGlu-L-Trp promoted regeneration of the hemopoietic progenitor population.

Thymodepressin inhibits migration of CD34+ cells from bone marrow in normal and granulocyte CSF-stimulated hemopoiesis.

We studied the effect of thymodepressin on migration and adhesion of mouse hemopoietic CD34+ cells under normal conditions and under the effect of granulocytic CSF. It was found that the peptide reduced the absolute number of CD34+ hemopoietic cells in the peripheral blood, increased the percent of cells bound to fibronectin and expressing receptor for integrin beta1 (CD29+) in the bone marrow of mice under normal conditions and after stimulation with granulocytic CSF, and reduced the relative number of cells carrying CXCR4 receptor for stromal factor-1 (CD184+) in the bone marrow (CD34+CD184+) and blood (CD184+) of mice stimulated with granulocytic CSF. The results suggest that thymodepressin can inhibit migration of CD34+ cells from bone marrow into peripheral blood under conditions of normal and granulocytic CSF-stimulated hemopoiesis.

Effects of structural and "mixed" isomers of Glu-Trp dipeptide on normal hemopoietic stem cells.

We studied the effects of optical (dd-, ll-, dl-, and ld-dipeptides with alpha-bond, EW) structural isomers and cyclic (dd-, ll-, dl-, and ld-dipeptides with gamma-bond, iEW) analogs of Glu-Trp synthetic dipeptide on the population of normal hemopoietic stem cells. Dipeptides containing lGlu (lGlu-lTrp, lGlu-dTrp) injected to mice were inert towards committed bone marrow CFU-S; dGlu-containing dipeptides (dGlu-dTrp, dGlu-lTrp) inhibited the growth of CFU-S-8; and LiGlu-dTrp stimulated these cells. Inhibitory or stimulatory effects of optical and chemical isomers of Glu-Trp dipeptide are determined by optical orientation and nature of peptide bond of Glu residue. The effects of cyclic and mixed peptides towards colony formation are similar to those of the corresponding linear dipeptides.

Effects of iEW synthetic peptide isomers on bone marrow colony-forming capacity in vivo.

Studies of cooperative effects of D- or L-isomers of iEW dipeptide and neuraminidase on the number of splenic CFU, comparison of the peptide effects on CD34+ cells and splenic CFU, and evaluation of the effects of iEW D- or L-isomers on parameters of T-cell activation showed that interactions of L-(iEW) and D-(iEW) with CD34+ surface receptors are realized through the same mechanism, while their different biological effects on hemopoietic precursor cells in vivo can be explained by their different influence on T-component of the microenvironment.

[Thymodepressin protects murine bone marrow CFU-S from the hyperthermic damage].

Was studied the influence of the Thymodepressin (dipeptide D-iEW--a new Russian immuno- and haemodepressant), on the hyperthermic sensitivity of haemopoietic precursors (CFU-S) and tumor model cells (EL-4 and Rauscher leukaemia). It was determined, that the injection of the Thymodepressin to donor mice, or the incubation with the preparation of the marrowy cells of normal mice provides the increasing of the CFU-S resistance to the following heating (43 degrees C). On the contrary, Thymodepressin-treated tumor cells became even more heat-sensitive. The data show that Thymodepressin can be useful for protection the haemopoietic precursors not only from radiation and chemotherapy, as it was shown earlier, but also from the hyperthermy.

[Immunogenic peptide neogen stimulates postradiation recovery thrombopoiesis]. / Immunomoduliator neogen stimuliruet postradiatsionnoe vosstanovlenie trombotsitopoéza.

In experiments on mice F1 total exposed to gamma-irradiation at the 5.0 Gy, showed that a intraperitoneal injection neogen at the dose 10 micrograms/kg oue time at the day and night during the 8 days after irradiation results in recovery of the number blood platelets and time issue of blood from standard wound to normal level on the week by compare with irradiated control animals.

[Postradiation recovery of hematopoiesis in mice affected by Neogen (IEW)]. / Postradiatsionnoe vosstanovlenie krovetvoreniia u myshei pod vliianiem neogena (IEW).

The effect of the synthetic peptide IEW (Neogen) with immunomodulating properties on postradiation recovery of haemopoiesis was investigated. We have shown that Neogen is a potential stimulator of haemopoiesis. The administration of Neogen after irradiation shortened duration of period of the recovery of the compartment of CFU-S-8 and the amount of bone marrow cells. The comparision of the effects of Neogen and GM-CSF (Leucomax) and G-CSF (Granocyte 34) have shown that the targets for these agents are probably different: polypotent CFU-S-for Neogen, and CFU-GM-for GM-CFS. Based on the results, we suggested the mechanism of Neogen effects on heamopoiesis.

Synthetic peptide thymodepressin promoted take of transplanted hemopoietic precursor cells in the bone marrow of irradiated mice.

We studied the possibility of using a new synthetic heme-inhibiting peptide thymodepressin for improving the efficiency of transplantations of syngeneic and allogeneic bone marrow. Thymodepressin was injected to recipients 3 times (48, 24, and 2 h) before irradiation and transplantation of bone marrow suspension. The yield of 9- and 12-day colonies increased, the number of proliferating CFU-S-12 and pre-CFU-S in recipient bone marrow increased in comparison with the control. In case of an allogeneic donor-recipient combination, the number of 9-day splenic colonies in thymodepressin-treated animals increased 5-fold compared to the control. We hypothesized that thymodepressin therapy and irradiation form an adaptive response of the recipient hemopoietic microenvironment in the bone marrow, which provides conditions for optimal functioning of donor hemopoietic precursors.

[The protective effect of thermal treatment before irradiation on CFUs from bone marrow of mice: a potential involvement of heat shock proteins]. / Zashchitnyi éffekt predradiatsionnoi termicheskoi obrabotki myshei na KOEs ikh kostnogo mozga: vozmozhnoe uchastie belkov teplovogo shoka.

It was studied on mice how prior whole body hyperthemia affects a colony-forming ability of bone marrow after gamma-irradiation. It was found that heating of the animals (42 degrees C, 10 min) 18-22 h before their total irradiation (4 Gy) increases 2-fold the level of CFUs8 and CFUs12 determined in the spleen exotest. The induced radioresistance correlated with accumulation of heat shock proteins, HSP70 and HSP25, in tissues of preheated mice. Injection of quercetin (a selective inhibitor of the heat shock protein synthesis) 0.5 h before the heating fully abolished both the subsequent heat shock protein accumulation and the rise in CFUs populations as compared with control. It is suggested that heat shock proteins, whose expression increases in response to hyperthermia, can play a role of endogenous radioprotectors. Possible mechanisms of their protective action under irradiation are discussed.

[The synthetic peptide D-(iEW) (thymodepressin) protects bone marrow CFU-S from ionizing radiation exposure]. / Sinteticheskii peptid D-(iEW) (timodepressin) zashchishchaet KOEs kostnogo mozga ot vozdeistviia ioniziruiushchei radiatsii.

Synthetic polypeptide D-(iEW) (Thymodepressin) was shown to reduce the bone marrow CFU-S in the S-phase of cell cycle. Apparently, due to this property the agent being administered 2 days before the irradiation with 4 Gy causes a prominent restoration of the CFU-S population afterwards. The 3-5 times higher value of this parameter as compared to the control (irradiation only) is likely to be connected to the increased "survival" of the Thymodepressin-protected CFU-S after the treatment with ionizing irradiation.

Reciprocal effect of optical isomerism of EW-dipeptides on immune response.

Dipeptides of the EW-sequence, consisting of D-amino acids, were shown to inhibit spleen colony formation both after in vitro treatment of bone marrow and after the peptide injection to the donor 2-48 h prior to bone marrow taking. The inhibiting effect of D-(EW) peptides can be eliminated by injection of thymic cells to the recipient. L-(EW) peptides have no influence on colony forming activity of intact bone marrow cells but stimulate regeneration of colony formation by irradiated (1 Gy) bone marrow. Unlike L-(EW), the D-(EW) peptides suppress the development of hemopoietic stem cells into the S-phase. Supposedly, D-(EW) represent a new generation of immunoactive peptides possessing of inhibiting activity.

[Palladium-containing compounds possess radiation-protective properties and enhance adaptive response of CFUs to radiation]. / Palladiisoderzhashchie soedineniia obladaiut radioprotektivnymi svoistvami i usilivaiut adaptivnyi otvek KOEs k radiatsionnomu vozdeistviiu.

Efasol and potassium tetrachloropalladate being injected into mice prior to irradiation with a dose of 150 sGy increase the colony forming activity of animals bone marrow cells transplanted in lethally irradiated recipient mice. The palladium presence in such compounds is supposed to be a reason of radioprotection. Upon the combined application of potassium tetrachloropalladate and irradiation of mice with an adaptive dose of 5 sGy a potentiation of individual effect of each separate agent to increase CFUs resistance against the consequent irradiation was observed.

Effect of the peptide of thymic origin (synthetic thymohexine-RKNVYR) on hemopoietic cell progenitors in intact and irradiated animals.

Thymohexine treatment of intact CFU-S was shown not to change their capacity to form colonies both in vivo and in vitro. Thymohexine, similarly to thymus cells, increased colony yield from rabbit antimouse brain antiserum (RAMBS)-treated bone marrow. Combined treatment with thymohexine and thymocytes did not restore colony formation by RAMB serum-treated bone marrow. Thymohexine halved the harmful effect of low doses of ionizing radiation on CFU-S, and, moreover, treatment with the peptide after 4 Gy-irradiation led to more intensive restoration of CFU-S population as compared to control.

[Effect of histone on hematopoietic stem cells (CFU-S) in normal and irradiated organism]. / Vozdeistvie gistona na krovetvornye kletki-predshestvenniki (KOEs) normal'nogo i obluchennogo organizma.

Radiotherapeutic activity of histone fractions H1 and H2A/H2B were studied. It was demonstrated that both fractions are able to reduce the damaging effect of ionizing radiation on spleen colony forming unit (CFU-S) population. Histone preparations stimulated colony-forming activity of bone marrow cells exposed to dose of 0.5-3.0 Gy both in the case of incubation with preparations and intravenous or intraperitoneal administration into recipients of irradiated cells. The effect of histones and accessory thymocytes on CFU-S population is compared.

[Radioprotective effect of synthetic immunomodulators on hemopoietic CFU-S]. / Radiozashchitnoe deistvie sinteticheskikh immunomoduliatorov na krovetvorenie KOEc.

The radiotherapeutic effect of thymogen (Glu-Trp) and thymohexin (Arg-Lys-Asp-Val-Tyr-Arg) synthetic peptide immunomodulators was investigated. Both thymogen and thymohexin were demonstrated to be able to reduce the damaging effect of ionizing radiation (1 Gy) on CFU-S by half. The treatment by these preparations after irradiation at dose of 4 Gy leads to more intensive restoration of CFU-S population as compared with control.

[Adaptive response in vivo: reasons for increase of radioresistance in CFU-S]. / Adaptivnyi otvet in vivo: prichiny povysheniia rediorezistentnosti KOEc.

The data concerning the reasons of CFU-S radioresistance increase after low dose irradiation of mice were obtained; the reparation processes in CFU-S adapted by low dose irradiation were shown to be more active than in intact ones. Colony formation increase was demonstrated to be more pronounced in adapted animals when they had been injected by 50 mcg of synthetic polyribonucleotide PolyI-PolyC two days before irradiation in challenge dose. The thymogen immunomodulator administration to adapted and intact donor animals leads to the increase of colony yield in equal extent.

[The replacement of accessory T-lymphocytes by synthetic peptides during the formation of splenic hematopoietic colonies]. / Zamena aktsessornykh T-limfotsitov sinteticheskimi peptidami v protsesse formirovaniia selezenochnykh krovetvornykh kolonii.

Whether accessory T cells can be replaced by the synthetic immunomodulators thymogen (Glu-Trp) and thymohexin (Arg-Lys-Asp-Val-Tyr-Arg) was studied. The latter immunomodulator was found to show a 3-fold increase in splenic colony formation after incubation of bone marrow cells with rabbit antimouse brain serum (RAMBS). The former preparation failed to show the same action. Its effect was close to that of thymocytes. When the recipients exposed to lethal irradiation were administered the RAMBS-treated bone marrow cells and one of the peptides, it was shown that in concomitant administration, thymohexin and thymocytes lost their ability to restore colony formation by RAMBS-treated bone marrow. Thymogen did not suppress the stimulating activity of thymocytes. It is suggested that the differences observed between the tested peptides in their ability to recover colony formation were determined by their structure.

[Phenomenon of adaptive resistance to gamma-irradiation of colony-forming units (CFU-S): Manifestation in exogenous test]. / Fenomen adaptivnoi rezistentnosti k gamma-oblucheniiu kolonieobrazuiushchikh edinits (KOE-S): usloviia proiavleniia v ékzoteste.

Adaptive response of colony forming units in mice spleen (CFU-S) was investigated in exotest after preirradiation with doses of 0.3-5.0 sGy of 60Co. Adaptive radioresistance was manifested from 4 hours till 28 days after each challenge dose. Low dose rate preirradiation is less effective as adaptive response inducing action than high dose rate one.

[The mechanisms of lymphoid regulation and the radiosensitivity of the hematopoietic system]. / Mekhanizmy limfoidnoi reguliatsii i radiochuvstvitel'nost' sistemy krovetvoreniia.

On the basis of the authors' own data and the literature it has been inferred that the key principles of the haemopoietic system regulation are similar to those of the immune system. The cells of a lymphoid origin are found, which implement helper and suppressor functions with respect to early haemopoiesis precursors; the influence of lymphokines on this compartment under the effect of radiation is described. Disturbances in the haemopoiesis system regulation, that result from various damaging effects, might be corrected by T-lymphocytes and lymphokines. The data obtained suggest that the formation of splenic colonies is the result of the interaction of some cell populations. That is why many radiobiological characteristics of CFUs may be attributed to partner cells (for instance, T-lymphocytes).