Lack of Cell Cycle Inhibitor p21 and Low CD4⁺ T Cell Suppression in Newborns After Exposure to IFN-β

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Umbilical cord-mesenchymal stem cells induce a memory phenotype in CD4+ T cells

Inflammation is a physiological state where immune cells evoke a response against detrimental insults. Finding a safe and effective treatment for inflammation associated diseases has been a challenge. In this regard, human mesenchymal stem cells (hMSC), exert immunomodulatory effects and have regenerative capacity making it a promising therapeutic option for resolution of acute and chronic inflammation. T cells play a critical role in inflammation and depending on their phenotype, they can stimulate or suppress inflammatory responses. However, the regulatory effects of hMSC on T cells and the underlying mechanisms are not fully elucidated. Most studies focused on activation, proliferation, and differentiation of T cells. Here, we further investigated memory formation and responsiveness of CD4+ T cells and their dynamics by immune-profiling and cytokine secretion analysis. Umbilical cord mesenchymal stem cells (UC-MSC) were co-cultured with either αCD3/CD28 beads, activated peripheral blood mononuclear cells (PBMC) or magnetically sorted CD4+ T cells. The mechanism of immune modulation of UC-MSC were investigated by comparing different modes of action; transwell, direct cell-cell contact, addition of UC-MSC conditioned medium or blockade of paracrine factor production by UC-MSC. We observed a differential effect of UC-MSC on CD4+ T cell activation and proliferation using PBMC or purified CD4+ T cell co-cultures. UC-MSC skewed the effector memory T cells into a central memory phenotype in both co-culture conditions. This effect on central memory formation was reversible, since UC-MSC primed central memory cells were still responsive after a second encounter with the same stimuli. The presence of both cell-cell contact and paracrine factors were necessary for the most pronounced immunomodulatory effect of UC-MSC on T cells. We found suggestive evidence for a partial role of IL-6 and TGFβ in the UC-MSC derived immunomodulatory function. Collectively, our data show that UC-MSCs clearly affect T cell activation, proliferation and maturation, depending on co-culture conditions for which both cell-cell contact and paracrine factors are needed

Development and application of quantitative real time PCR and RT-PCR assays that discriminate between the full-length and truncated herpes simplex virus thymidine kinase gene

Allogeneic donor T lymphocytes manipulated genetically to express the herpes simplex virus thymidine kinase (HSV-TK) gene have emerged as promising tools to alter the balance between graft versus host disease and graft versus leukemia after allogeneic stem cell transplantation, since they can be eliminated selectively in vivo with ganciclovir. Recently, it was reported that in SFCMM-3, an HSV-TK-encoding retroviral vector, two cryptic splice sites in the HSV-TK sequence led to the generation of an HSV-TK splice variant (deltaHSV-TK) that encodes a ganciclovir-resistant gene product. In order to quantify wtHSV-TK and deltaHSV-TK RNA levels we have developed two real time Taqman PCR assays. We demonstrate that the sensitivity of both PCR assays is 10(-4). It was found that the splice variant is generated in the packaging cell line and results in approximately 4.8+/-1.9% of virions that contain deltaHSV-TK RNA. After transduction of human T cells no significant increase in deltaHSV-TK RNA could be detected. Thus, at maximum 4.2+/-1.2% of T cells transduced with SFCMM-3 will be resistant to ganciclovir due to this mechanism only. Together, these assays provide a powerful method to monitor patients in future clinical trial

A new xenograft model for graft-versus-host disease by intravenous transfer of human peripheral blood mononuclear cells in RAG2-/- gammac-/- double-mutant mice

The safe application of new strategies for the treatment of graft-versus-host disease (GVHD) is hampered by the lack of a clinically relevant model for preclinical testing. Current models are based on intraperitoneal transfer of human peripheral blood mononuclear cells (huPBMCs) into NOD-SCID (nonobese diabetic-severe combined immunodeficient)/SCID mice. Intravenous transfer would be preferred but this has always been ineffective. We developed a new model for xenogeneic GVHD (X-GVHD) by intravenous transfer of huPBMCs into RAG2-/- gammac-/-mice. Our results show a high human T-cell chimerism of more than 20% (up to 98%) in more than 90% of mice, associated with a consistent development of XGVHD within 14 to 28 days and a total mortality rate of 85% shorter than 2 months. After murine macrophage depletion, engraftment was earlier and equally high with lower doses of huPBMCs. Human macrophages were also absent in these mice. Purified huCD3+ cells showed a similar X-GVH effect with contribution of both CD4 and CD8 phenotypes. Human immunoglobulins and cytokines were produced in diseased mice. One of 30 mice developed chronic X-GVHD with skin histology similar to human GVHD. In conclusion, we present a new model for X-GVHD by intravenous transfer of huPBMCs in RAG2-/- gammac-/- mice. Murine and human macrophages do not seem to be necessary for acute X-GVHD in this mode

Transcriptome assists prognosis of disease severity in respiratory syncytial virus infected infants

Respiratory syncytial virus (RSV) causes infections that range from common cold to severe lower respiratory tract infection requiring high-level medical care. Prediction of the course of disease in individual patients remains challe

Effect of FHA and Prn on Bordetella pertussis colonization of mice is dependent on vaccine type and anatomical site.

Bordetella pertussis vaccine escape mutants that lack expression of the pertussis antigen pertactin (Prn) have emerged in vaccinated populations in the last 10-20 years. Additionally, clinical isolates lacking another acellular pertussis (aP) vaccine component, filamentous hemagglutinin (FHA), have been found sporadically. Here, we show that both whole-cell pertussis (wP) and aP vaccines induced protection in the lungs of mice, but that the wP vaccine was more effective in nasal clearance. Importantly, bacterial populations isolated from the lungs shifted to an FHA-negative phenotype due to frameshift mutations in the fhaB gene. Loss of FHA expression was strongly selected for in Prn-deficient strains in the lungs following aP but not wP vaccination. The combined loss of Prn and FHA led to complete abrogation of bacterial surface binding by aP-induced serum antibodies. This study demonstrates vaccine- and anatomical site-dependent adaptation of B. pertussis and has major implications for the design of improved pertussis vaccines

BCG-induced trained immunity enhances acellular pertussis vaccination responses in an explorative randomized clinical trial.

Acellular pertussis (aP) booster vaccines are central to pertussis immunization programs, although their effectiveness varies. The Bacille Calmette-Guérin (BCG) vaccine is a prototype inducer of trained immunity, which enhances immune responses to subsequent infections or vaccinations. While previous clinical studies have demonstrated that trained immunity can protect against heterologous infections, its effect on aP vaccines in humans is unknown. We conducted a clinical study in order to determine the immunological effects of trained immunity on pertussis vaccination. Healthy female volunteers were randomly assigned to either receive BCG followed by a booster dose of tetanus-diphteria-pertussis inactivated polio vaccine (Tdap-IPV) 3 months later (BCG-trained), BCG + Tdap-IPV concurrently, or Tdap-IPV followed by BCG 3 months later. Primary outcomes were pertussis-specific humoral, T- and B-cell responses and were quantified at baseline of Tdap-IPV vaccination and 2 weeks thereafter. As a secondary outcome in the BCG-trained cohort, ex vivo leukocyte responses were measured in response to unrelated stimuli before and after BCG vaccination. BCG vaccination 3 months prior to, but not concurrent with, Tdap-IPV improves pertussis-specific Th1-cell and humoral responses, and also increases total memory B cell responses. These responses were correlated with enhanced IL-6 and IL-1β production at the baseline of Tdap-IPV vaccination in the BCG-trained cohort. Our study demonstrates that prior BCG vaccination potentiates immune responses to pertussis vaccines and that biomarkers of trained immunity are the most reliable correlates of those responses