Effects of BCG and Corynebacterium parvum on the haemopoietic precursor cells in continuously irradiated mice: possible mechanisms of action in immunotherapy

Effects of glucan on bone marrow

Bone marrow damage represents a significant problem in cancer treatment. Therefore, it is clear that the pharmacologic protection against bone marrow damage is of considerable interest, since the development of novel and effective medical approaches to combat radiation or cytotoxic damage are of major importance not only to the medical field but also to several industries and the military. This review represents a summary of our knowledge of the effects of various glucans on bone marrow protection.

Antitumor, hematostimulative and radioprotective action of water-soluble derivative of propolis (WSDP)

Several studies suggest that dietary supplementation with antioxidant can influence the response to chemotherapy as well as the development of adverse side effects caused by treatment with chemotherapeutic agents. Using CBA mouse model, we investigated a clinically potential use of a water-soluble derivative of propolis (WSDP) in the treatment of various cytopenias induced by radiation and/or chemotherapy. Also, the antimetastatic efficiency of WSDP given intraperitoneally alone or in combination with chemotherapeutic agents and their effects on the blood leukocytes count as well as on hematopoiesis were studied. Tumor was a transplantable mammary carcinoma (MCa) of CBA mouse. Metastases in the lung were generated by injecting viable tumor cells intravenously (iv). WSDP (50 or 150 mg/kg) exerted a significant antimetastatic effect (P < 0.001) when given either before or after tumor cell inoculation. In combined treatment WSDP and Epirubicin profoundly inhibited metastasis formation; this synergistic effect is maximal when Epirubicin and WSDP were administrated after tumor cell inoculation. Positive outcome of combined treatment with WSDP and Epirubicin was also found regarding the number of red and white blood cells in peripheral blood while in mice treated with Epirubicin alone the significant drop in all hematological parameters was noticed on day 13 after tumor cell inoculation. Furthermore, when WSDP (50 mg/kg) was given perorally (po) for 20 consecutive days an increased number of exogenous CFUs was found in treated mice. WSDP given either for 20 or 40 days increased cellularity of hematopoietic tissue and the number of leucocytes in peripheral blood; prolonged treatment with WSDP also elevated myeloid and megakaryocytic types of CFUs. To conclude, these findings indicate that the combination of WSDP with chemotherapeutics could increase the antimetastatic potential of chemotherapeutic agents; these findings suggest the benefits of potential clinical trials using WSDP combined with chemotherapeutic agents in order to maximize their antitumor activity and minimize postchemotherapeutic or radiotherapeutic deteriorated reactions.

Immunostimulating lipopeptide, LtriP (RP 56142): comparison of the effect on hepatic cytochrome P 450 modulation and radioprotection in male and female of three mouse strains

The sex-dependent effect of lauroyl-L-Ala-D-gamma-Glu-L,L-A2pmNH2 (LtriP, RP 56142) on hepatic microsomal cytochromes P 450 (cyt P 450) was studied in three mouse strains NMRI, C3H/OuJ and C3H/HeJ. In NMRI and C3H/OuJ, strains which are responsive to bacterial lipopolysaccharides (LPS-responsive), regardless of the sex of the mouse, significant decrease in the amount of cyt P 450 was observed after LtriP treatment, with a concomitant reduction in ethoxyresorufin-O-deethylase (cyt P 450 1A-dependent) and 7-ethoxycoumarin-O-deethylase activities. This was not seen in C3H/HeJ (LPS-hyporesponsive) mice. These effects may be related to LtriP-dependent cytokine induction, since neither LtriP nor LPS stimulated interleukin-1 (IL-1) secretion by C3H/HeJ macrophages. 11- and 12-hydroxylations (11- and 12-OH) of lauric acid were compared in C3H/OuJ and C3H/HeJ mice. LtriP depressed the total enzymatic conversion of lauric acid in the two strains without modification of the 11/12-OH ratio for C3H/OuJ or male C3H/HeJ mice. However, in females C3H/HeJ mice this decrease was particularly significant and concerned especially the 12-OH activity (a marker of cyt P450 4A family). Although males of the three strains were more sensitive to irradiation than females, LtriP exerted a sex-independent radioprotection on NMRI and C3H/OuJ mice. Its radioprotective effect was illustrated by the preservation of all the enzymatic activities studied in treated NMRI mice, contrary to irradiated control animals. In contrast, for the C3H/HeJ strain, males were not protected by LtriP treatment and, furthermore, females showed a marked sensitization to irradiation. The effects in CH3/HeJ strain implicate LtriP in the control of cyt P 450 induction and of sensitivity to irradiation independently of IL-1 induction.

Radioprotective effects of the immunostimulating lauroylpeptide LtriP (RP 56142)

The lipopeptide lauroyl-L-Ala-gamma-D-Glu-L,L-A2pm (LtriP) increased the resistance of mice to the lethal effect of gamma-ray irradiation. The radioprotective effect was dependent on the doses of LtriP and of radiation. Maximum survival was observed when the lipopeptide was injected on two successive days before irradiation. This activity seems to be related to immunostimulating functions, since the non-immunostimulating analog lauroyl-L-Ala-gamma-D-Glu-D,D-A2pm-Gly, containing D,D-diaminopimelic acid, was not radioprotective. The protective activity might result from an induction of cytokines, such as IL-1, TNF and M-CSF, since LtriP induced the mRNA expression and the secretion of these immunomodulators.

Distant metastasis facilitated by BCG: spread of tumour cells injected in the BCG-primed site

Tumour metastasis in BCG-pretreated mice was studied using a methylcholanthrene-induced fibrosarcoma in C3H/He mice. When tumour cells were injected into the BCG-primed site, distant metastasis occurred in the lungs and the popliteal lymph node, through this tumour did not metastasize in normal mice. Such metastases were increased in proportion to the number of tumour cells injected into the BCG-primed site, and developed soon after tumour challenge. Concomitant immunity developed well in the mice bearing such metastases, but did not inhibit metastatic growth. Experiments using 125I-labelled SRBC or tumour cells revealed that such cells egressed rapidly from the BCG-primed site. When the tumour was inoculated into the contralateral foot to the BCG-primed site, the incidence and the number of metastases was reduced. Furthermore, BCG infection induced an increase of platelet count. I.v. injection of this tumour induced marked thrombocytopenia in normal mice. Administration of pentoxifylline, a methylxanthine derivative before tumour challenge reduced such metastases. These findings suggest that the changes in peripheral blood, such as increased platelet count and increased release of tumour cells from the injection site, facilitated distant metastasis in BCG-pretreated mice.

Prolonged effect of Corynebacterium parvum stimulation on granulopoiesis

An intravenous injection of 548 microgram of killed Corynebacterium parvum (C. parvum) into C57BL mice led to a significant increase in the number of both committed stem cells (GM-CFC) and proliferating cells of bone marrow granulocytic series. This increase appeared 24 h after the injection of the bacterium, persisted in varying levels until the 4th week and was accompanied by a marked and prolonged granulocytosis. The proportion of GM-CFC in DNA synthesis was found to be increased 1, 2, and 5 d after injection of C. parvum. Increased serum lysozyme levels were observed on the 9th and 15th d. These findings suggest that C. parvum can stimulate granulopoiesis in the animal system. This property of the bacterium should be considered when a combined chemo-immunotherapy schedule has to be applied.