Is cytomegalovirus infection a major cause of T cell alterations after (autologous) bone-marrow transplantation?

Effects of cytomegalovirus infection on the mRNA expression of collagens and matrix metalloproteinases in gingival fibroblasts

BACKGROUND AND OBJECTIVE

The purpose of this in vitro investigation was to study the effects of human cytomegalovirus infection on the mRNA expression for collagens I and III and for matrix metalloproteinases 1 and 2 in gingival fibroblasts.

MATERIAL AND METHODS

Gingival fibroblasts were experimentally infected with the Towne strain of human cytomegalovirus and the kinetics of expression of mRNA for collagens I and III and for matrix metalloproteinases 1 and 2 was studied at different time-points. Total RNA was isolated at the indicated time, and the reverse transcription-polymerase chain reaction was used to analyze the level of mRNA expression. In addition, gingival specimens were obtained from 14 periodontitis and from three non-periodontitis subjects and mRNA analysis for collagens and metalloproteinases was carried out. Nested polymerase chain reaction was used to determine the presence or absence of human cytomegalovirus in subgingival samples from each subject.

RESULTS

The infection of gingival fibroblasts with human cytomegalovirus during a 0-72-h period resulted in progressive reduction in the expression of mRNA for collagens I and III (p < 0.05). A higher concentration of human cytomegalovirus resulted in varying degrees of mRNA reduction, suggesting a virally mediated effect. Biopsies from human cytomegalovirus-positive individuals with periodontitis had a higher expression of mRNA for collagens I and III than biopsies from human cytomegalovirus-negative individuals. An up-regulation in the mRNA expression of matrix metalloproteinases 1 and 2 over time was observed (p < 0.05). Analysis of mRNA expression in gingival biopsies demonstrated higher expression of matrix metalloproteinase-1 in human cytomegalovirus-positive periodontitis specimens compared with human cytomegalovirus-negative periodontitis specimens.

CONCLUSION

Altered expression of mRNA for collagens and metalloproteinases in human cytomegalovirus-infected gingival fibroblasts should be considered as possible modifying mechanisms in periodontitis-infected sites.

Reconstitution of the immune system after hematopoietic stem cell transplantation in humans

Hematopoietic stem cell transplantation is associated with a severe immune deficiency. As a result, the patient is at high risk of infections. Innate immunity, including epithelial barriers, monocytes, granulocytes, and NK cells recovers within weeks after transplantation. By contrast, adaptive immunity recovers much slower. B- and T-cell counts normalize during the first months after transplantation, but in particular, T-cell immunity may remain impaired for years. During the last decade, much of the underlying mechanisms have been identified. These insights may provide new therapies to accelerate recovery.

Interactions between viruses in transplant recipients

Viral coinfections may modulate disease expression, enhance pathogenicity, and lead to greater cumulative immunosuppression in the host. The pathophysiological basis of these may be direct virus-virus interactions, effect of cohabitating viruses on host cell function, or impaired host immune responses. The interrelationship between viral pathogens has become increasingly more relevant and its scope wider as new or previously unrecognized viruses continue to emerge as pathogens in transplant recipients. The pathways and mediators that modulate biological activity represent potential targets for immunomodulatory interventions as adjunctive therapies for transplant recipients.

Influence of cytomegalovirus seropositivity on outcome after T cell-depleted bone marrow transplantation: contrasting results between recipients of grafts from related and unrelated donors

We analyzed the effect of cytomegalovirus (CMV) serostatus on overall survival (OS) and transplant-related mortality (TRM) in 253 consecutively treated patients receiving partially T cell-depleted (TCD) bone marrow from either matched related donors (MRDs; n=205) or matched unrelated donors (MUDs; n=48). Short-course, low-dose preemptive therapy with ganciclovir was provided as soon as a positive antigenemia assay result was obtained. Ganciclovir prophylaxis, which was identical to preemptive therapy, was given to patients with acute graft-versus-host disease (GVHD) grades II-IV who had to be treated with high-dose steroids. In recipients of transplants from MRDs, inferior OS and increased TRM were predicted by extensive chronic GVHD (P<.001). High-risk disease status and older age adversely influenced OS (P=.001) and TRM (P=.002), respectively; older age resulted in a trend toward decreased OS (P=.066). In recipients of transplants from MUDs, OS and TRM were strongly influenced by patient CMV seropositivity (P=.013 and.007, respectively). In conclusion, CMV seropositivity is not an adverse risk factor for OS and TRM in recipients of transplants from MRDs. However, in recipients of transplants from MUDs, patient CMV seropositivity strongly affects OS and TRM.

Reconstruction of the immune system after unrelated or partially matched T-cell-depleted bone marrow transplantation in children: functional analyses of lymphocytes and correlation with immunophenotypic recovery following transplantation

Reconstitution of the immune system following T-cell-depleted bone marrow transplantation (BMT) in children has yet to be fully elucidated. Thus, we prospectively studied the recovery of immune function in 64 children who underwent T-lymphocyte-depleted marrow transplants using either matched family member donors or matched unrelated donors. We measured in vitro posttransplantation proliferative responses to phytohemagglutinin (PHA), concanavalin A, pokeweed mitogen, and Candida albicans antigen and assessed unidirectional allogeneic mixed-lymphocyte culture (MLC) responses at various times. A total of 129 healthy individuals served as normal controls for these assays. Responses to T-cell mitogens normalized within 12 months posttransplantation, while MLC responses normalized by 9 months. The presence of graft-versus-host disease (grade II or greater) and cytomegalovirus infection was associated with delays in immune function recovery. Importantly, immune function recovery correlated temporally with a rise in peripheral lymphocyte count. In contrast, the CD4/CD8 ratio was not predictive of immune recovery. Knowledge of immune function recovery may guide clinicians in devising strategies to minimize the risk of infection post-BMT.

Will killing the last HIV1 particle cure AIDS patients? Doesn't CMV activation and/or a graft-versus-host component of the disease, also have to be considered? I. First of two parts

Before the discovery of HIV1 and HIV2, I proposed as the mechanism of HIV1-AIDS complex, a graft versus host reaction (GvH) induced by transfusion or seringe or sexual act blood transferred lymphocytes: this was based on the clinical, pathological and biological, and especially immunological similarities. I have treated ten HIV1-AIDS complex patients in the last phase with five virostatics, distributed in three week sequence combinations of 3 or 4, each differing from the preceeding and following ones. After follow-up between one and three and a half years, the results can be summarized as such: when the viral loads fall below the detectable level, the CD8+ CD57+ suppressor T-cell and CD8+ CD57- cytotoxic T-cell numbers tend towards normal levels (approximately 200/mL), but the CD4 counts go up to a maximum of only 394, far from the normal level (800). Moreover, none of these subsets present a significant coefficient of correlation with the HIV1 load, which indicates that these immunologic markers and the viral one provide different information. I suggest the hypothesis according to which HIV1-AIDS complex comprises other components than HIV1 infection, such as a) the evoked GvH, which would occur early enough and might explain this CD4 incomplete restoration by virostatics, and b) cytomegalovirus (CMV) activation which occurs later. The second part of this editorial review will be published in a part II of the "Dossier" on AIDS. It will be devoted to the discussion of GvH and CMV infection systematic treatments.

Evidence for transfer of cellular and humoral immunity to cytomegalovirus from donor to recipient in allogeneic bone marrow transplantation

In order to study the importance of the immune status of the donor in the development of immunity after allogeneic bone marrow transplantation (BMT), we monitored 23 cytomegalovirus (CMV) antibody-positive BMT recipients for humoral and cellular immunity to CMV, of whom 12 had a CMV antibody-positive and 11 a CMV antibody-negative marrow donor. Lymphocyte proliferation to CMV recovered significantly earlier after BMT in recipients of marrow from a CMV+ donor (10.4 weeks after BMT) compared with the recipients of marrow from CMV- donors (16.7 weeks after BMT, P less than 0.05). This seemed to be specific, as lymphocyte proliferation to phytohaemagglutinin and Candida were not different between the to groups. IgM responses after active infection were seen in both groups, but initial IgG rises without IgM were seen only in recipients of marrow from CMV+ donors (P less than 0.05). Lymphocyte proliferative or humoral immune responses to CMV were not detected in any of the patients in a control group consisting of nine CMV- recipients. These results indicate that T cell memory to CMV is transferred with donor marrow from CMV+ donors, leading in most patients to direct IgG anti-CMV responses and to quicker recovery of cellular immunity to CMV.

Pneumonitis in bone marrow transplant recipients results from a local immune response

Eighteen recipients of allogeneic T cell-depleted bone marrow who developed 22 episodes of interstitial pneumonitis were investigated by bronchoalveolar lavage for the cause of pneumonitis. The cells obtained were examined using a panel of monoclonal antibodies with immunocytochemical techniques to identify lymphocyte subsets and the presence of surface molecules indicative of lymphocyte activation. The majority of patients had an excess of lymphocytes in lavage and most of these cells were positively stained with the McAb recognizing the CD8 antigen (suppressor/cytotoxic type T cells). Although the proportions of CD4+ (helper type) T cells were below normal, the absolute numbers were within normal limits, thus the CD4:CD8 ratio was consistently 1:1 or less. A large proportion of the CD8+ cells displayed HLA-DR molecules (RFDR1+), interleukin-2 (IL-2) receptors (CD25+) and high concentration of CD7 antigen (RFT2+). Further analysis revealed that most CD8+ cells were CD5+ (RFT1+) yet a large proportion (20-40%) were CD5-. A majority of CD8+ cells was also CD38+ (RFT10+) and Leu7+. No clear correlation between the emergence of a raised proportion of activated CD8+ cells and diagnosed cytomegalovirus infection was found. These results demonstrate, however, that cells with the phenotype of the resident T cells of the bronchial epithelium (CD8+CD5-) emerge to the air spaces and express activation markers. This raises the intriguing paradox of an aggressive local immune response occurring in an otherwise immunosuppressed group of patients.

Cytomegalovirus (CMV) infections in patients receiving CMV-IgG-hyperimmunoglobulin prophylaxis after bone-marrow transplantation

Conditioning therapy with aggressive chemotherapy and irradiation induces a state of transient combined immunodeficiency in bone-marrow transplant recipients. This promotes the occurrence of severe cytomegalovirus (CMV) infections, the most frequent lethal complication after bone-marrow transplantation (BMT) at present. Forty-four BMT recipients received CMV-IgG-hyperimmunoglobulin for CMV prophylaxis intravenously. The efficacy of this prophylaxis and possible risk factors for the occurrence of CMV-induced interstitial pneumonia (IP) were analyzed. Risk factors for the promotion of a CMV-IP were: additional immunosuppressive therapy after BMT, CMV-positive serostatus of the recipient, CMV-seropositive granulocyte transfusion, CMV infection immediately prior to BMT, and HLA-haploidentical BMT. In this study the incidence of graft-versus-host disease was low and was not associated with the incidence of CMV infections. The use of T-cell-depleted grafts did not result in increased CMV infections or IP and may possibly have improved the immunological reconstitution.

Cytomegalovirus infections in adult T-cell leukemia patients

Cytomegalovirus (CMV) infection frequently occurred in patients with malignant lymphoma of T-cell origin, especially with adult T-cell leukemia (ATL). This was evidenced by histopathological examination at autopsy, isolation of CMV, and detection of CMV antibodies that indicate recent or active infection. Cellular immune response was suppressed in most ATL patients when examined by skin hypersensitivity reaction to purified protein derivatives (PPD), streptococcal antigens (SuPs), and phytohaemoagglutinin (PHA). None of the CMV-positive patients reacted to them. Thus, the presence of tumor cells of T-cell origin and the absence of skin hypersensitivity reaction seem to be risk factors for CMV infection. Each CMV isolate exhibited unique DNA fingerprints, suggesting that cross-infection of CMV did not occur among the ATL patients on the same ward.

Transfusion-associated viral infections

Viral infections are a frequent occurrence following transfusion of blood products. While generally benign, these infections are capable of causing significant morbidity and mortality. Therefore, it is prudent to follow several general approaches diligently to reduce the risks of these infections in patients undergoing transfusions of blood products. These suggested measures include the following: 1. Prescribe and administer blood and blood products only when absolutely needed. 2. Use volunteer blood donors only. 3. Avoid use of pooled blood products when possible. 4. Use only blood and blood products that have been appropriately tested for HBsAg and HIV. 5. Use ALT determinations to screen blood products and eliminate those with high level. 6. Avoid the use of clotting-factor concentrates but, if necessary, use only those which have been heat-treated. 7. Limit use of leukocyte transfusion. 8. Use only CMV seronegative blood and blood products or frozen deglycerolized red cells in patients at high risk for posttransfusion CMV infection.

Changes in plasma beta 2 microglobulin concentrations after allogeneic bone marrow transplantation

Plasma concentrations of beta 2 microglobulin (B2M), the light chain of the class I major histocompatibility complex, were measured serially in 26 patients undergoing allogeneic bone marrow transplantation (BMT). The concentrations fell after conditioning treatment, and recovered when the marrow was transplanted. Bacterial infection did not influence B2M concentration, but nine of 22 episodes of acute graft versus host disease were associated with raised concentrations. Increased plasma B2M concentrations were also a feature of eight episodes of chronic graft versus host disease, and these fell after treatment. Reactivation of herpes simplex, varicella zoster, or cytomegalovirus infections were also accompanied by raised B2M concentrations. Three patients with cytomegalovirus pneumonitis had high concentrations of plasma B2M, the rise starting between five and 22 days before onset of symptoms. Although it is non-specific, serial measurement of plasma B2M in patients undergoing BMT may be clinically useful in monitoring chronic graft versus host disease.

Reduced risk of recurrent leukaemia in bone marrow transplant recipients after cytomegalovirus infection

The first 72 consecutive bone-marrow transplant recipients with haematological malignancies (29 with acute nonlymphoblastic leukaemia, 31 with acute lymphoblastic leukaemia, nine with CML and three with myelofibrosis, IgA myeloma and T-cell lymphoma, respectively) were investigated for the frequency of relapses 1 year or later after bone-marrow transplantation. Seven relapses occurred from 30 to 850 d after transplantation (median 180 d). All relapses occurred in patients with acute leukaemia less than or equal to 18 years of age with a high risk for relapse, i.e. transplanted in second or later remission or with more than 10% blasts in the marrow before transplantation. Among all patients the probability of relapse was increased in patients without cytomegalovirus (CMV) infection (P = 0.001) and in patients without chronic GVHD (P = 0.049). Among leukaemic patients less than or equal to 18 years of age with a high risk of relapse all relapses occurred in patients (n = 11) without CMV infection, whereas no relapses were seen in patients (n = 13) with CMV infection (P = 0.006). Known risk factors for leukaemic relapse were comparable in both groups.

Influence of graft-versus-host disease prophylaxis on early T-lymphocyte regeneration following allogeneic bone marrow transplantation

An early decrease in the ratio between T4+ and T8+ T lymphocytes has been shown to correlate with the development of grade II-IV GVHD in allogeneic bone marrow transplant (BMT) recipients receiving methotrexate (MTX) as prophylaxis for acute graft-versus-host disease (GVHD). This study compares the onset of T-cell regeneration in patients receiving cyclosporin A (CyA) with those receiving MTX. Firstly, lymphoid recovery occurred at a significantly faster rate in the patients on CyA. Secondly, in those patients, the repopulation of T4+ and T8+ T cells started simultaneously, whereas in patients on MTX the repopulation of the T8+ subset lagged about a week behind that of the T4+ subset. Thirdly, the decrease in the T4/T8 ratios as a function of the lymphocyte counts occurred at a significantly slower rate in the patients on CyA than in those on MTX. Thus, the differences in the onset of T-cell regeneration in BMT recipients on CyA as compared with those on MTX abolished the correlation of the T4/T8 ratio changes with grades II-IV GVHD as described in patients receiving MTX.

Lung diseases after bone marrow transplantation. Results of a clinical, radiological, histological, immunological and lung function study

The case histories of 72 subsequently treated patients - 44 with acute leukemia, 10 with chronic myeloid leukemia, 16 with severe aplastic anemia and 2 with neuroblastoma - were analyzed after bone marrow transplantation (BMT) with respect to pulmonary diseases. Thirty-eight patients suffered from a total of 51 pulmonary complications, which led to death in 20. Of 13 patients, 3 died of bacterial pneumonia, all of them during granulocytopenia; 2 of 6 patients died of fungal pneumonia and 2 out of 3 of a mixed bacterial-mycotic infection. Adult respiratory distress syndrome (ARDS) led to death in 2 patients. A granulocyte count under 500/microliter correlated significantly (P less than 0.002) with the fatal outcome of bacterial, fungal and ARDS pneumonia as well as with bronchitis. Viral pneumonia led to death in 8 of 9 patients; in each there was a significant correlation (P less than 0.05) with graft-versus-host disease (GvHD). Patients with repeated episodes of pulmonary illness had significantly more chronic GvHD (P less than 0.05); several of these patients displayed a reduction in helper T cells and an increase in suppressor T cells in the peripheral blood. The natural killer (NK) cells were reduced and the percentage of activated NK cell level lay between 6% and 69%. B-cells were absent or deficient. These findings explain in part the absence of specific antibody reactivity. Five of these patients also contracted GvHD-associated obstructive bronchiolitis, which did not respond to therapy. Pulmonary infiltrates of unknown origin (including idiopathic interstitial pneumonia) occurred in 8 of the patients (11.1%), with a fatal outcome in 3 patients. Significant changes (P less than 0.05) in lung function after BMT appeared in the form of reduced vital capacity (VC) increased residual volume (RV) and an increase in RV expressed as the percentage of total lung capacity. Pulmonary diseases were the most common complication and cause of death in our patients after BMT.