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1.  Transplantation Outcomes for Severe Combined Immunodeficiency, 2000–2009 
The New England journal of medicine  2014;371(5):434-446.
The Primary Immune Deficiency Treatment Consortium was formed to analyze the results of hematopoietic-cell transplantation in children with severe combined immunodeficiency (SCID) and other primary immunodeficiencies. Factors associated with a good transplantation outcome need to be identified in order to design safer and more effective curative therapy, particularly for children with SCID diagnosed at birth.
We collected data retrospectively from 240 infants with SCID who had received transplants at 25 centers during a 10-year period (2000 through 2009).
Survival at 5 years, freedom from immunoglobulin substitution, and CD3+ T-cell and IgA recovery were more likely among recipients of grafts from matched sibling donors than among recipients of grafts from alternative donors. However, the survival rate was high regardless of donor type among infants who received transplants at 3.5 months of age or younger (94%) and among older infants without prior infection (90%) or with infection that had resolved (82%). Among actively infected infants without a matched sibling donor, survival was best among recipients of haploidentical T-cell–depleted transplants in the absence of any pretransplantation conditioning. Among survivors, reduced-intensity or myeloablative pre-transplantation conditioning was associated with an increased likelihood of a CD3+ T-cell count of more than 1000 per cubic millimeter, freedom from immunoglobulin substitution, and IgA recovery but did not significantly affect CD4+ T-cell recovery or recovery of phytohemagglutinin-induced T-cell proliferation. The genetic subtype of SCID affected the quality of CD3+ T-cell recovery but not survival.
Transplants from donors other than matched siblings were associated with excellent survival among infants with SCID identified before the onset of infection. All available graft sources are expected to lead to excellent survival among asymptomatic infants. (Funded by the National Institute of Allergy and Infectious Diseases and others.)
PMCID: PMC4183064  PMID: 25075835
3.  Cord-Blood-Derived Mesenchymal Stromal Cells Downmodulate CD4+ T-Cell Activation by Inducing IL-10-Producing Th1 Cells 
Stem Cells and Development  2012;22(7):1063-1075.
The mechanisms by which mesenchymal stromal cells (MSCs) induce immunomodulation are still poorly understood. In the current work, we show by a combination of polymerase chain reaction (PCR) array, flow cytometry, and multiplex cytokine data analysis that during the inhibition of an alloantigen-driven CD4+ T-cell response, MSCs induce a fraction of CD4+ T-cells to coexpress interferon-γ (IFNγ) and interleukin-10 (IL-10). This CD4+ IFNγ+ IL-10+ cell population shares properties with recently described T-cells originating from switched Th1 cells that start producing IL-10 and acquire a regulatory function. Here we report that IL-10-producing Th1 cells accumulated with time during T-cell stimulation in the presence of MSCs. Moreover, MSCs caused stimulated T-cells to downregulate the IFNγ receptor (IFNγR) without affecting IL-10 receptor expression. Further, the inhibitory effect of MSCs could be reversed by an anti-IFNγR-blocking antibody, indicating that IFNγ is one of the major players in MSC-induced T-cell suppression. Stimulated (and, to a lesser extent, resting) CD4+ T-cells treated with MSCs were able to inhibit the proliferation of autologous CD4+ T-cells, demonstrating their acquired regulatory properties. Altogether, our results suggest that the generation of IL-10-producing Th1 cells is one of the mechanisms by which MSCs can downmodulate an immune response.
PMCID: PMC3608091  PMID: 23167734
4.  B Cell Reconstitution for SCID: Should a conditioning regimen be used in the treatment of SCID? 
Bone marrow transplantation has resulted in life-saving sustained T cell reconstitution in many SCID infants, but correction of B cell function has been more problematic. At the annual meeting of the Primary Immunodeficiency Treatment Consortium held in Boston, MA on April 27, 2012, a debate was held regarding the use of pre-transplant conditioning versus no pre-transplant conditioning in an effort to address this problem. Reviews of the literature were made by both debaters and there was agreement that there was a higher rate of B cell chimerism and a lower number of patients who required ongoing IG replacement therapy in centers that used pre-transplant conditioning. However, there were still patients who required IG replacement in those centers, so pre-transplant conditioning did not guarantee development of B cell function. RB presented data on B cell function according to the molecular defect of the patient, and showed that patients with IL7Rα, ADA and CD3 chain gene mutations can have normal B cell function post-transplantation with only host B cells. EH presented a statistical analysis of B cell function in published reports and showed that only a conditioning regimen that contained busulfan was significantly associated with better B cell function post-transplantation. The question is whether the risk of immediate and longterm toxicity in using busulfan is justified, particularly in SCID patients with DNA repair defects and in very young SCID newborns who will be detected by newborn screening.
PMCID: PMC3615028  PMID: 23465660
Severe combined immunodeficiency; conditioning regimen; haematopoietic stem cell transplantation; B cell function; immunoglobulin therapy
5.  Whole-Exome Sequencing Reveals a Rapid Change in the Frequency of Rare Functional Variants in a Founding Population of Humans 
PLoS Genetics  2013;9(9):e1003815.
Whole-exome or gene targeted resequencing in hundreds to thousands of individuals has shown that the majority of genetic variants are at low frequency in human populations. Rare variants are enriched for functional mutations and are expected to explain an important fraction of the genetic etiology of human disease, therefore having a potential medical interest. In this work, we analyze the whole-exome sequences of French-Canadian individuals, a founder population with a unique demographic history that includes an original population bottleneck less than 20 generations ago, followed by a demographic explosion, and the whole exomes of French individuals sampled from France. We show that in less than 20 generations of genetic isolation from the French population, the genetic pool of French-Canadians shows reduced levels of diversity, higher homozygosity, and an excess of rare variants with low variant sharing with Europeans. Furthermore, the French-Canadian population contains a larger proportion of putatively damaging functional variants, which could partially explain the increased incidence of genetic disease in the province. Our results highlight the impact of population demography on genetic fitness and the contribution of rare variants to the human genetic variation landscape, emphasizing the need for deep cataloguing of genetic variants by resequencing worldwide human populations in order to truly assess disease risk.
Author Summary
Recent resequencing of the whole genome or the coding part of the genome (the exome) in thousands of individuals has described a large excess of low frequency variants in humans, probably arising as a consequence of recent rapid growth in human population sizes. Most rare variants are private to specific populations and are enriched for functional mutations, thus potentially having some medical relevance. In this study, we analyze whole-exome sequences from over a hundred individuals from the French-Canadian population, which was founded less than 400 years ago by about 8,500 French settlers who colonized the province between the 17th and 18th centuries. We show that in a remarkably short period of time this population has accumulated substantial differences, including an excess of rare, functional and potentially damaging variants, when compared to the original European population. Our results show the effects of population history on genetic variation that may have an impact on genetic fitness and disease, and have implications in the design of genetic studies, highlighting the importance of extending deep resequencing to worldwide human populations.
PMCID: PMC3784517  PMID: 24086152
7.  Higher Doses of Subcutaneous IgG Reduce Resource Utilization in Patients with Primary Immunodeficiency 
Journal of Clinical Immunology  2011;32(2):281-289.
The recommended dose of IgG in primary immunodeficiency (PID) has been increasing since its first use. This study aimed to determine if higher subcutaneous IgG doses resulted in improved patient outcomes by comparing results from two parallel clinical studies with similar design. One patient cohort received subcutaneous IgG doses that were 1.5 times higher than their previous intravenous doses (mean 213 mg/kg/week), whereas the other cohort received doses identical to previous subcutaneous or intravenous doses (mean 120 mg/kg/week). While neither cohort had any serious infections, the cohort maintained on higher mean IgG dose had significantly lower rates of non-serious infections (2.76 vs. 5.18 episodes/year, P < 0.0001), hospitalization (0.20 vs. 3.48 days/year, P < 0.0001), antibiotic use (48.50 vs. 72.75 days/year, P < 0.001), and missed work/school activity (2.10 vs. 8.00 days/year, P < 0.001). The higher-dose cohort had lower health care utilization and improved indices of well being compared to the cohort treated with traditional IgG doses.
PMCID: PMC3305876  PMID: 22193916
Primary immunodeficiency; subcutaneous IgG replacement therapy; infection rate; hospitalization rate; Hizentra
9.  Ionizing radiation-induced long-term expression of senescence markers in mice is independent of p53 and immune status 
Aging cell  2010;9(3):398-409.
Exposure to IR has been shown to induce the formation of senescence markers, a phenotype that coincides with life-long delayed repair and regeneration of irradiated tissues. We hypothesised that IR-induced senescence markers could persist long-term in vivo, possibly contributing to the permanent reduction in tissue functionality. Here we show that mouse tissues exposed to a sublethal dose of IR display persistent (up to 45 weeks, the maximum time analysed) DNA damage foci and increased p16INK4a expression, two hallmarks of cellular senescence and aging. BrdU labelling experiments revealed that IR-induced damaged cells are preferentially eliminated, at least partially, in a tissue dependent manner. Unexpectedly, the accumulation of damaged cells was found to occur independent from the DNA damage response modulator p53, and from an intact immune system, as their levels were similar in wild-type and Rag2−/−γC−/− mice, the latter being deficient in T, B and NK cells. Together, our results provide compelling evidence that exposure to IR induces long-term expression of senescence markers in vivo, an effect that may contribute to the reduced tissue functionality observed in cancer survivors.
PMCID: PMC2894262  PMID: 20331441
cancer; cellular senescence; DNA damage; immune system; ionizing radiation; p16; p53
10.  Exome sequencing identifies mutations in the gene TTC7A in French-Canadian cases with hereditary multiple intestinal atresia 
Journal of Medical Genetics  2013;50(5):324-329.
Congenital multiple intestinal atresia (MIA) is a severe, fatal neonatal disorder, involving the occurrence of obstructions in the small and large intestines ultimately leading to organ failure. Surgical interventions are palliative but do not provide long-term survival. Severe immunodeficiency may be associated with the phenotype. A genetic basis for MIA is likely. We had previously ascertained a cohort of patients of French-Canadian origin, most of whom were deceased as infants or in utero. The goal of the study was to identify the molecular basis for the disease in the patients of this cohort.
We performed whole exome sequencing on samples from five patients of four families. Validation of mutations and familial segregation was performed using standard Sanger sequencing in these and three additional families with deceased cases. Exon skipping was assessed by reverse transcription-PCR and Sanger sequencing.
Five patients from four different families were each homozygous for a four base intronic deletion in the gene TTC7A, immediately adjacent to a consensus GT splice donor site. The deletion was demonstrated to have deleterious effects on splicing causing the skipping of the attendant upstream coding exon, thereby leading to a predicted severe protein truncation. Parents were heterozygous carriers of the deletion in these families and in two additional families segregating affected cases. In a seventh family, an affected case was compound heterozygous for the same 4bp deletion and a second missense mutation p.L823P, also predicted as pathogenic. No other sequenced genes possessed deleterious variants explanatory for all patients in the cohort. Neither mutation was seen in a large set of control chromosomes.
Based on our genetic results, TTC7A is the likely causal gene for MIA.
PMCID: PMC3625823  PMID: 23423984
Gastroenterology; Genetics; Developmental; Molecular genetics

Results 1-10 (10)