Treatment decision-making in sickle cell disease patients

Sickle cell disease (SCD) is a blood disorder with few treatment options currently available. However, in recent years, there has been much progress toward developing new therapies and curative treatments to help patients with SCD. Stem cell transplant remains the only approved curative treatment for SCD, but new clinical trials are being initiated using gene therapy and gene editing. We surveyed patients with sickle cell disease (N=9) about attitudes toward stem cell transplant, gene therapy to add a new healthy gene, gene editing to up-regulate fetal hemoglobin, or gene editing to correct the point mutation. The participants read a fact sheet that included objective information on each curative treatment. When asked which curative treatment each participant would choose, all four options were selected at least once. The most highly selected treatment was gene correction gene editing (N=4). Participants generally agreed that the four treatment options are beneficial but were more mixed in their thoughts on whether the options are dangerous. Reasons for selecting a particular curative treatment were variable, but the most selected reasons were perception of a cure (N=4) or decreased severity (N=4), and not needing a donor (N=4). We are at the beginning stages of understanding how patients with SCD make decisions about curative treatments. Currently, patients may be interested in any of the four possibilities for curative treatments, with gene correction gene editing as the most popular choice. Reasons for choosing one treatment over another are mixed.

CRISPR-based gene editing enables FOXP3 gene repair in IPEX patient cells

The prototypical genetic autoimmune disease is immune dysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome, a severe pediatric disease with limited treatment options. IPEX syndrome is caused by mutations in the forkhead box protein 3 (FOXP3) gene, which plays a critical role in immune regulation. As a monogenic disease, IPEX is an ideal candidate for a therapeutic approach in which autologous hematopoietic stem and progenitor (HSPC) cells or T cells are gene edited ex vivo and reinfused. Here, we describe a CRISPR-based gene correction permitting regulated expression of FOXP3 protein. We demonstrate that gene editing preserves HSPC differentiation potential, and that edited regulatory and effector T cells maintain their in vitro phenotype and function. Additionally, we show that this strategy is suitable for IPEX patient cells with diverse mutations. These results demonstrate the feasibility of gene correction, which will be instrumental for the development of therapeutic approaches for other genetic autoimmune diseases.

Interferon priming is essential for human CD34+ cell-derived plasmacytoid dendritic cell maturation and function

Plasmacytoid dendritic cells (pDC) are essential for immune competence. Here we show that pDC precursor differentiated from human CD34+ hematopoietic stem and progenitor cells (HSPC) has low surface expression of pDC markers, and has limited induction of type I interferon (IFN) and IL-6 upon TLR7 and TLR9 agonists treatment; by contrast, cGAS or RIG-I agonists-mediated activation is not altered. Importantly, after priming with type I and II IFN, these precursor pDCs attain a phenotype and functional activity similar to that of peripheral blood-derived pDCs. Data from CRISPR/Cas9-mediated genome editing of HSPCs further show that HSPC-pDCs with genetic modifications can be obtained, and that expression of the IFN-α receptor is essential for the optimal function, but dispensable for the differentiation, of HSPC-pDC percursor. Our results thus demonstrate the biological effects of IFNs for regulating pDC function, and provide the means of generating of gene-modified human pDCs.

Coccidioidal antigen reactive CD4+ T-lymphocytes in the cerebrospinal fluid in coccidioides immitis meningitis

CSF lymphocytes from patients with Coccidioides immitis meningitis exhibited a significant antigen-specific response to in vitro stimulation with C. immitis antigens. In some patients, lesser responses to control antigens (Candida and PPD) were also detected. Antigen-specific responses by CSF lymphocytes were seen early in the course of this disease as well as several years after patients had entered remission. When compared to CSF cells, the response of autologous peripheral blood mononuclear cells was similar but of a much smaller magnitude and at times undetectable. Fluorescence activated cell sorting revealed an increased percentage of CD3+ (T-cells), CD4+ (helper/inducer) and CD3+/HLA-DR+ (activated T-cell) cells in the CSF of C. immitis meningitis patients compared to their blood. Most of the antigen-specific proliferative response resided in the CD4+ lymphocyte subset. CSF T-cell proliferation assays may have a role in the diagnosis of C. immitis meningitis.

Deletion of chromosome 1p: a short review

A further patient with a deletion of 1p is described, bringing the number of reported cases to 13. The cytogenetic derivation of the deletions and the clinical phenotype are reviewed. The range of breakpoints and small number of cases result in no clearly defined phenotype. Facial dysmorphism, clinodactyly of the fifth finger, mental retardation and heart defects are, however, most frequently described, with a high-arched palate, in particular, seen in deletions distal to p34.

Validation of a model of non-rhegmatogenous retinal detachment

To study the movement of subretinal fluid, we have injected fluid into the subretinal space through a glass micropipette and monitored its resorption. This technique has been criticized as a model of non-rhegmatogenous detachment because the small retinal hole made by the micropipette might allow efflux of subretinal fluid into the vitreous. The present experiments answer this criticism: we found that sealing the micropipette hole with cyanoacrylate, mucilage or an air bubble had no effect on the rate of subretinal fluid resorption, and detachments with two to five micropipette holes did not resorb faster than those with only one.