Lentiviral Vector-Mediated Correction of a Mouse Model of Leukocyte Adhesion Deficiency Type I

Abstract

Leukocyte adhesion deficiency type I (LAD-I) is a primary immunodeficiency caused by mutations in the ITGB2 gene and is characterized by recurrent and life-threatening bacterial infections. These mutations lead to defective or absent expression of β2 integrins on the leukocyte surface, compromising adhesion and extravasation at sites of infection. Three different lentiviral vectors (LVs) conferring ubiquitous or preferential expression of CD18 in myeloid cells were constructed and tested in human and mouse LAD-I cells. All three hCD18-LVs restored CD18 and CD11a membrane expression in LAD-I patient-derived lymphoblastoid cells. Corrected cells recovered the ability to aggregate and bind to sICAM-1 after stimulation. All vectors induced stable hCD18 expression in hematopoietic cells from mice with a hypomorphic Itgb2 mutation (CD18HYP), both in vitro and in vivo after transplantation of corrected cells into primary and secondary CD18HYP recipients. hCD18+ hematopoietic cells from transplanted CD18HYP mice also showed restoration of mCD11a surface co-expression. The analysis of in vivo neutrophil migration in CD18HYP mice subjected to two different inflammation models demonstrated that the LV-mediated gene therapy completely restored neutrophil extravasation in response to inflammatory stimuli. Finally, these vectors were able to correct the phenotype of human myeloid cells derived from CD34+ progenitors defective in ITGB2 expression. These results support for the first time the use of hCD18-LVs for the treatment of LAD-I patients in clinical trials.

Lentiviral Vector Gene Therapy Protects XCGD Mice From Acute Staphylococcus aureus Pneumonia and Inflammatory Response

“…34 Our study included a wide distribution of VCN (ranging from 0.3 to 9.8). While these VCNs are in line with previous studies from our group and others [36][37][38] it is expected that lower VCNs would be observed in the clinical application based on our previous studies in human CD34+ cells, 23 and clinical trials in other therapeutic areas. 34,39 Unfortunately, no published data is available regarding the protection from the infections in clinical trials with lentiviral vectors encoding for gp91phox.…”

Evolving Gene Therapy in Primary Immunodeficiency

“…107 More recently, the canine (canine LAD [CLAD]) and murine models of disease have been successfully treated using HSCs transduced with either foamy or lentiviral vectors expressing CD18. 108,109 In many of these conditions, preclinical efficacy and safety studies using improved viral vectors, including vector platforms developed from other classes of retrovirus such as foamy and avian viruses (which may have enhanced safety in terms of genotoxicity), are currently being undertaken in order to determine clinical applicability.…”

Advances in the gene therapy of monogenic blood cell diseases

“…Our studies showed the efficacy and safety of a gene therapy approach in an LAD‐I mouse model using a SIN‐LV in which a chimeric internal promoter—already used in the gene therapy of X‐CGD patients—drives the expression of CD18. The Chim.hCD18‐LV conferred phenotypic correction in mouse LAD‐I leukocytes, which then expressed the heterodimer in their membrane and migrated to inflamed sites . Based on these experimental results it is expected that LAD‐I will be added to the list of PIDs successfully treated by gene therapy.…”

“…A very low and transient engraftment of corrected cells was observed in this trial, probably due to the absence of patient's conditioning and to the fact that corrected LAD‐I progenitor cells do not develop proliferative advantage. Recent experimental data have raised expectations for gene therapy in these patients. Our studies showed the efficacy and safety of a gene therapy approach in an LAD‐I mouse model using a SIN‐LV in which a chimeric internal promoter—already used in the gene therapy of X‐CGD patients—drives the expression of CD18.…”