Impact of CMV Reactivation, Treatment Approaches, and Immune Reconstitution in a Nonmyeloablative Tolerance Induction Protocol in Cynomolgus Macaques.

BACKGROUND: Cytomegalovirus (CMV) infection is a serious complication in immunosuppressed patients, specifically transplant recipients. Here, we describe the development and use of an assay to monitor the incidence and treatment of CMV viremia in a Cynomolgus macaque model of bone marrow transplantation (BMT) for tolerance induction. We address the correlation between the course of viremia and immune reconstitution. METHODS: Twenty-one animals received a nonmyeloablative conditioning regimen. Seven received cyclosporine A for 28 days and 14 received rapamycin. A CMV polymerase chain reaction assay was developed and run twice per week to monitor viremia. Nineteen recipients were CMV seropositive before BMT. Immune reconstitution was monitored through flow cytometry and CMV viremia was tracked via quantitative polymerase chain reaction. RESULTS: Recipients developed CMV viremia during the first month post-BMT. Two animals developed uncontrollable CMV disease. CMV reactivation occurred earlier in cyclosporine A-treated animals compared with those receiving rapamycin. Post-BMT, T-cell counts remained significantly lower compared with pretransplant levels until CMV reactivation, at which point they increased during the viremic phase and approached pretransplant levels 3 months post-BMT. Management of CMV required treatment before viremia reached 10 000 copies/mL; otherwise clinical symptoms were observed. High doses of ganciclovir resolved the viremia, which could subsequently be controlled with valganciclovir. CONCLUSIONS: We developed an assay to monitor CMV in Cynomolgus macaques. CMV reactivation occurred in 100% of seropositive animals in this model. Rapamycin delayed CMV reactivation and ganciclovir treatment was effective at high doses. As in humans, CD8 T cells proliferated during CMV viremia.

Contribution of individual psychological and psychosocial factors to symptom severity and time-to-recovery after naturally-occurring acute infective illness: The Dubbo Infection Outcomes Study (DIOS).

BACKGROUND: Substantial heterogeneity exists in both the severity of symptoms experienced as part of the sickness response to naturally-occurring infections, and the time taken for individuals to recover from these symptoms. Although contributing immunological and genetic factors have been previously been explored, less is known about the role of individual psychological and psychosocial factors, which may modulate the host immune response, or contribute independently, to symptom severity and duration. METHODS: Longitudinally-collected data from 484 Caucasian participants (mean age: 33.5 years; 51% women) experiencing a naturally-occurring acute infective illness enrolled in the prospective Dubbo Infection Outcome Study (DIOS) were analysed. At intake and subsequent follow-up assessments, self-report questionnaires were used to ascertain individual psychological and psychosocial characteristics and symptom information. Principal component analysis was applied to symptom data to derive endophenotype severity scores representing discrete symptom domains (fatigue, mood, pain, neurocognitive difficulties) and an overall index of severity. The contribution of individual psychological (trait neuroticism, locus of control, and illness behaviours) and psychosocial factors (relative socioeconomic advantage) to endophenotype severity at baseline were examined using multivariable linear regression models; interval-censored flexible parametric proportional hazards survival models were used to explore time to recovery (defined using within-sample negative threshold values). RESULTS: After controlling for time since symptom onset, greater levels of trait neuroticism consistently predicted greater symptom severity across all symptom domains (all p's < 0.015). Similarly, greater relative socioeconomic disadvantage was significantly associated with greater severity across all endophenotypes (p's < 0.025) except neurocognitive disturbance. Locus of control and illness behaviours contributed differentially across endophenotypes. Reduced likelihood of recovery was significantly predicted by greater initial symptom severity for all endophenotypes (all p's < 0.001), as well as higher levels of trait neuroticism. CONCLUSIONS: Individual psychological and psychosocial factors contribute to the initial severity and to the prolonged course of symptoms after naturally-occurring infective illnesses. These factors may play an independent role, represent a bias in symptom reporting, or reflect increased stress responsivity and a heightened inflammatory response. Objective metrics for severity and recovery are required to further elucidate their roles.

Altered thymic CD4+ T-cell recovery after allogeneic hematopoietic stem cell transplantation is critical for nocardiosis.

PURPOSE OF THE STUDY: Nocardia affects immunocompromised human host exhibiting an altered cell-mediated immunity. Infectious risk after allogeneic hematopoietic cell transplantation (AHCT) is significantly correlated to the recovery status of donor-derived immune system, especially CD4+ T-cells reconstitution and thymopoiesis. The purpose of this paper is to highlight a lack of cell-mediated immunity recovery for patients presenting a nocardiosis compared to a control cohort. PATIENTS AND METHODS: This is a case control retrospective monocentric study. We retrospectively analyzed a monocentric cohort of 15 cases of nocardiosis after AHCT and we explored the degree of patients' immunosuppression by phenotyping circulating lymphoid subpopulations, including NK cells, CD8+ T-cells, CD4+ T-cells and CD19+ B-cells. We focused on CD4+ T-cell subsets to appreciate thymic output, especially on naive CD4+ T-cells (NTE, CD45RA+/RO- CD4+ T-cells) and recent thymic emigrants (RTE, CD4+CD45RA+/RO-/CD31+). Infected patients were paired with a control cohort of patients with identical transplantation characteristics screened on hematological disease, AHCT conditioning, primary graft-versus-host disease (GHVD) prophylaxis, graft type, sex, age, and season at the AHCT and data concerning immunological reconstitution were compared. RESULTS: At onset of nocardiosis, circulating lymphocytes and CD4+ T-cells means count were respectively 730/µL and 162/µL. CD8+ T-cells, CD56+ NK cells and CD19+ B-cells means count were respectively 362/µL, 160/µL, 112/µL. CD4+ T-cells subpopulations, naïve CD4+ T-cells production was impaired with NTE and RTE means count at 26/µL and 11/µL respectively. Comparison between nocardiosis cohort and control cohort over time highlight significant lower cellular count for lymphocytes, CD4+ T-cells, NTE and RTE with p = 0.001, p < 0.001, p < 0.001, p < 0.001 respectively. CONCLUSION: Immune recovery monitoring follow-up after AHCT is of particular importance to identify patients susceptible to develop Nocardiosis. Efficient microbiological investigations toward Nocardia such PCR should be used in case of compatible clinical presentation.

Immune regeneration in irradiated mice is not impaired by the absence of DPP9 enzymatic activity.

The ubiquitous intracellular protease dipeptidyl peptidase 9 (DPP9) has roles in antigen presentation and B cell signaling. To investigate the importance of DPP9 in immune regeneration, primary and secondary chimeric mice were created in irradiated recipients using fetal liver cells and adult bone marrow cells, respectively, using wild-type (WT) and DPP9 gene-knockin (DPP9S729A) enzyme-inactive mice. Immune cell reconstitution was assessed at 6 and 16 weeks post-transplant. Primary chimeric mice successfully regenerated neutrophils, natural killer, T and B cells, irrespective of donor cell genotype. There were no significant differences in total myeloid cell or neutrophil numbers between DPP9-WT and DPP9S729A-reconstituted mice. In secondary chimeric mice, cells of DPP9S729A-origin cells displayed enhanced engraftment compared to WT. However, we observed no differences in myeloid or lymphoid lineage reconstitution between WT and DPP9S729A donors, indicating that hematopoietic stem cell (HSC) engraftment and self-renewal is not diminished by the absence of DPP9 enzymatic activity. This is the first report on transplantation of bone marrow cells that lack DPP9 enzymatic activity.

Contribution of arterial spin-labelling MRI in a case with immune reconstitution inflammatory syndrome.

Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS), which occurs most often in HIV-infected patients, is an exacerbation of inflammatory reactions related to opportunistic infections as well as primary CNS malignancies both of which mostly occur in HIV-infected patients. However, differential diagnoses are challenging both clinically and radiologically. We describe a patient with CNS-IRIS due to toxoplasmosis whose 11C-methionine uptake suggested lymphoma but whose arterial spin-labelling MRI led to the correct diagnosis.

National Institutes of Health Hematopoietic Cell Transplantation Late Effects Initiative: The Immune Dysregulation and Pathobiology Working Group Report.

Immune reconstitution after hematopoietic stem cell transplantation (HCT) beyond 1 year is not completely understood. Many transplant recipients who are free of graft-versus-host disease (GVHD) and not receiving any immunosuppression more than 1 year after transplantation seem to be able to mount appropriate immune responses to common pathogens and respond adequately to immunizations. However, 2 large registry studies over the last 2 decades seem to indicate that infection is a significant cause of late mortality in some patients, even in the absence of concomitant GVHD. Research on this topic is particularly challenging for several reasons. First, there are not enough long-term follow-up clinics able to measure even basic immune parameters late after HCT. Second, the correlation between laboratory measurements of immune function and infections is not well known. Third, accurate documentation of infectious episodes is notoriously difficult. Finally, it is unclear what measures can be implemented to improve the immune response in a clinically relevant way. A combination of long-term multicenter prospective studies that collect detailed infectious data and store samples as well as a national or multinational registry of clinically significant infections (eg, vaccine-preventable severe infections, opportunistic infections) could begin to address our knowledge gaps. Obtaining samples for laboratory evaluation of the immune system should be both calendar and eventdriven. Attention to detail and standardization of practices regarding prophylaxis, diagnosis, and definitions of infections would be of paramount importance to obtain clean reliable data. Laboratory studies should specifically address the neogenesis, maturation, and exhaustion of the adaptive immune system and, in particular, how these are influenced by persistent alloreactivity, inflammation, and viral infection. Ideally, some of these long-term prospective studies would collect information on long-term changes in the gut microbiome and their influence on immunity. Regarding enhancement of immune function, prospective measurement of the response to vaccines late after HCT in a variety of clinical settings should be undertaken to better understand the benefits as well as the limitations of immunizations. The role of intravenous immunoglobulin is still not well defined, and studies to address it should be encouraged.

Successful immune reconstitution by means of hematopoietic stem cell transplantation in a Colombian patient with chronic granulomatous disease.

INTRODUCTION: Chronic granulomatous disease is a primary immunodeficiency that results from mutations in proteins of the NADPH oxidase system that affect the microbicidal activity of phagocytes. Immune reconstitution by hematopoietic stem cell transplantation is currently the only curative therapy for this disease.  OBJECTIVE: To describe the clinical and molecular characterization of a patient with X-linked chronic granulomatous disease and the successful immune reconstitution by means of a hematopoietic stem cell transplantation.  METHODS: The respiratory burst was measured by flow cytometry using the dihydrorodamine 123 (DHR) oxidation test in neutrophils of peripheral blood. Mutational analysis of CYBB was performed by PCR amplification in complementary DNA, as well as sequencing and comparative genomic hybridization in genomic DNA. HLA-identical stem cells from the patient's younger brother were used for the transplantation and reduced intensity pre-transplantation conditioning was administered. Post-transplantation immune reconstitution was evaluated periodically by serial complete blood counts and DHR 123 in peripheral blood neutrophils.  RESULTS: The diagnosis of X-linked chronic granulomatous disease resulted from a hemizygous deletion affecting Xp21.1 that included the entire CYBB. Post-transplantation engraftment was documented in platelets and peripheral blood neutrophils at days 10 and 11, respectively. Total hematological reconstitution was achieved by day 30 post-transplantation and no complications or infections have been observed in the three years since the transplantation.  CONCLUSION: Hemopoietic stem cell transplantation allows for total reconstitution of the immune function related to microbicidal activity of phagocytic cells from patients with X-linked chronic granulomatous disease.