| The human cytomegalovirus (CMV), a member of the beta-herpesvirinae subfamily, is a widespread pathogen responsible for generally asymptomatic and persistent infections in healthy people. It may, however, reactivate and cause severe disease in the absence of an effective immune response, as in immunologically immature and immunocompromised individuals, such as organ allografting, malignant, and human immunodeficiency virus (HlV)-infected patients. It is known that CMV could infect many kinds of cells, including some tumor cells. Recent laboratory investigations implicate that CMV infection might interfere with several key cellular pathways, leading to enhanced survival, angiogenesis, cell motility and adhesion.Tumor relapse and CMV infection are major concerns in the therapy of hematopoietic malignancies by bone marrow transplantation (BMT). It was reported that there were higher rates of cytomegalovirus reactivation in patients with multiple myeloma (MM) after autologous or CD34+ stem cell selected transplantation , but no attention so far has been given to a possible pathogenetic interplay between CMV and MM cells. MM is a malignant tumor from B cell origin. It has been proved that the cytokine interleukin-6 (IL-6) is a very important growth factor for myeloma. IL-6 may both stimulate myeloma growth and prevent apoptosis of malignant plasma cells by paracrine and autocrine machenism. CMV infection has been shown to induce IL-6 secretion in many cells. For example, CMV could infect HF cells and induce IL-6 in the cells through activation of the transcription factor, NF- k B. But it is unknown whether CMV could infect MM cells and whatchanges after the infection. So our studies were initiated to address the following questions: (1) Can CMV infect and replicate in MM cells? (2) Can CMV inhibit apoptotic responses induced by growth factor withdrawal of MM cell? (3) What are the possible mechanisms of these changes?In part 1, CMV AD 169 was propagated in HF human fibroblasts. It was found that HF cells infected by CMV turned from thin shuttle shape to round and thick ball shape, even escaping from wall. Cell shape changed more dominantly as the CMV titer increased. With transmission electron microscope, a lot of CMV particles were found in the nucleus and plasma of HF cells infected by CMV. With RT-PCR, HF cells infected by CMV could express IE mRNA. With flow cytometry, it was found that there were much more CMV pp65 antigen positive cells when infected by 100> 10, 1 TCID50 of CMV. HF cells and bone marrow stromal cells (BMSC) were regarded as the positive control. MM cell line KM3 and RPMI 8226 cells were infected by 100 > 10, 1 TCID50 of CMV, then the three assays above were used to detect the cells infection and reactivation of CMV. Data demonstrate that CMV-infected KM3 and RPMI 8226 cells could express IE mRNA compared with the uninfected and there were very bright bands of CMV IE mRNA in cells infected with 100> 10 TCID50 of CMV; CMV particles could be found in the cells infected by 100 TCID50 of CMV compared with the mock-infected cells with transmission electron microscope; CMV pp65 antigen positive cells was 5.06%±1.90% and 3.29%±0.92% when KM3 cells were infected by 100, 10 TCID50 of CMV, which was significant higher than the control group (0.38%±0.40%) (P value were 0.001 > 0.006 respectively) ,and CMV pp65 antigen positive cells increased as the CMV titer increased (r=0885, P<0.01) .As to RPMI 8226 cells, CMV pp65 antigen positive cells were 4.3% when cells were infected by 100 TCID50 of CMV, while there were no CMV pp65 antigen positive cells in the mock-infected RPMI 8226 cells. So it can be concluded that CMV can infect MM cells and replicate in the cells.It is known that BMSC are permissive for CMV replication in vitro and in vivo, BMSC was one source of CMV latency and reactivation. Our researches have confirmed this in nucleus acid, protein and cellular micro structural level. We also found that shape of BMSC could be changed like HF cells after CMV infection.CMV infection ha...
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