RESUMEN
DNA-modifying technologies, such as the CRISPR-Cas9 system, are promising tools in the field of gene and cell therapies. However, high and prolonged expression of DNA-modifying enzymes may cause cytotoxic and genotoxic side effects and is therefore unwanted in therapeutic approaches. Consequently, development of new and potent short-term delivery methods is of utmost importance. Recently, we developed non-integrating gammaretrovirus- and MS2 bacteriophage-based Gag.MS2 (g.Gag.MS2) particles for transient transfer of non-retroviral CRISPR-Cas9 RNA into target cells. In the present study, we further improved the technique by transferring the system to the alpharetroviral vector platform (a.Gag.MS2), which significantly increased CRISPR-Cas9 delivery into target cells and allowed efficient targeted knockout of endogenous TP53/Trp53 genes in primary murine fibroblasts as well as primary human fibroblasts, hepatocytes, and cord-blood-derived CD34+ stem and progenitor cells. Strikingly, co-packaging of Cas9 mRNA and multiple single guide RNAs (sgRNAs) into a.Gag.MS2 chimera displayed efficient targeted knockout of up to three genes. Co-transfection of single-stranded DNA donor oligonucleotides during CRISPR-Cas9 particle production generated all-in-one particles, which mediated up to 12.5% of homology-directed repair in primary cell cultures. In summary, optimized a.Gag.MS2 particles represent a versatile tool for short-term delivery of DNA-modifying enzymes into a variety of target cells, including primary murine and human cells.
RESUMEN
Patient material from rare diseases such as very early-onset inflammatory bowel disease (VEO-IBD) is often limited. The use of patient-derived induced pluripotent stem cells (iPSCs) for disease modeling is a promising approach to investigate disease pathomechanisms and therapeutic strategies. We successfully developed VEO-IBD patient-derived iPSC lines harboring a mutation in the IL-10 receptor ß-chain (IL-10RB) associated with defective IL-10 signaling. To characterize the disease phenotype, healthy control and VEO-IBD iPSCs were differentiated into macrophages. IL-10 stimulation induced characteristic signal transducer and activator of transcription 3 (STAT3) and suppressor of cytokine signaling 3 (SOCS3) downstream signaling and anti-inflammatory regulation of lipopolysaccharide (LPS)-mediated cytokine secretion in healthy control iPSC-derived macrophages. In contrast, IL-10 stimulation of macrophages derived from patient iPSCs did not result in STAT3 phosphorylation and subsequent SOCS3 expression, recapitulating the phenotype of cells from patients with IL-10RB deficiency. In line with this, LPS-induced cytokine secretion (e.g., IL-6 and tumor necrosis factor-α (TNF-α)) could not be downregulated by exogenous IL-10 stimulation in VEO-IBD iPSC-derived macrophages. Correction of the IL-10RB defect via lentiviral gene therapy or genome editing in the adeno-associated virus integration site 1 (AAVS1) safe harbor locus led to reconstitution of the anti-inflammatory response. Corrected cells showed IL-10RB expression, IL-10-inducible phosphorylation of STAT3, and subsequent SOCS3 expression. Furthermore, LPS-mediated TNF-α secretion could be modulated by IL-10 stimulation in gene-edited VEO-IBD iPSC-derived macrophages. Our established disease models provide the opportunity to identify and validate new curative molecular therapies and to investigate phenotypes and consequences of additional individual IL-10 signaling pathway-dependent VEO-IBD mutations.
RESUMEN
Samples from patients with rare diseases, such as primary immunodeficiencies, are often limited, which hampers careful analysis of the pathomechanisms involved in immune cell dysregulation. To overcome this issue, induced pluripotent stem cells (iPSCs) represent an almost inexhaustible cell source and thus provide an excellent opportunity to generate disease models for rare diseases and to validate new therapeutic approaches. To obtain a better understanding of primary immunodeficiencies associated with the interleukin (IL)-10 signaling pathway, for example, very-early-onset inflammatory bowel disease (VEO-IBD), we generated genetic knockouts (KOs) of IL-10RA (IL-10 receptor α-chain) and IL-10RB (IL-10 receptor ß-chain) as well as the downstream targets of the IL-10-receptor (IL-10R) signal transducers and activators of transcription (STAT)1 and STAT3 via an sgRNA (single-guide RNA)-CRISPR-Cas9-expressing lentiviral system. IL-10 signaling-associated KO models and a VEO-IBD patient-derived iPSC clone were differentiated into macrophages for disease models. IL-10R- or STAT3-deficient disease models showed no IL-10-induced BCL3 or SOCS3 expression, whereas lipopolysaccharide (LPS) stimulation induced IL-10R independently of BCL3 and SOCS3 expression. Cytokine secretion profiles from iPSC-derived macrophage disease models showed that IL-10 was involved in many inflammatory cytokine secretions, which indicated formation of both anti- and proinflammatory macrophage phenotypes. Macrophage-secreted cytokines were separated into IL-10R- and STAT3-dependent (IL-6, TNF-α), or into IL-10R-, STAT1-, and STAT3-dependent cytokines (CCL2, CXCL10). Importantly, lentiviral correction restored IL-10-mediated regulation of LPS-induced cytokine secretion in corrected IL-10RB, STAT1, and VEO-IBD patient-derived disease models. Furthermore, treatment of IL-10RB-deficient macrophages with anti-inflammatory small molecules (SB202190, filgotinib) reduced proinflammatory cytokine secretion patterns. Taken together, the described iPSC KO models gave new insights into the pathomechanisms of immune cell dysregulation and served as model systems to test potential therapeutic approaches, including lentiviral gene therapy and targeted small-molecule treatment.
