Dual-locus, dual-HDR editing permits efficient generation of antigen-specific regulatory T cells with robust suppressive activity

Adoptive regulatory T (Treg) cell therapy is predicted to modulate immune tolerance in autoimmune diseases, including type 1 diabetes (T1D). However, the requirement for antigen (ag) specificity to optimally orchestrate tissue-specific, Treg cell-mediated tolerance limits effective clinical application. To address this challenge, we present a single-step, combinatorial gene editing strategy utilizing dual-locus, dual-homology-directed repair (HDR) to generate and specifically expand ag-specific engineered Treg (EngTreg) cells derived from donor CD4+ T cells. Concurrent delivery of CRISPR nucleases and recombinant (r)AAV homology donor templates targeting FOXP3 and TRAC was used to achieve three parallel goals: enforced, stable expression of FOXP3; replacement of the endogenous T cell receptor (TCR) with an islet-specific TCR; and selective enrichment of dual-edited cells. Each HDR donor template contained an alternative component of a heterodimeric chemically inducible signaling complex (CISC), designed to activate interleukin-2 (IL-2) signaling in response to rapamycin, promoting expansion of only dual-edited EngTreg cells. Using this approach, we generated purified, islet-specific EngTreg cells that mediated robust direct and bystander suppression of effector T (Teff) cells recognizing the same or a different islet antigen peptide, respectively. This platform is broadly adaptable for use with alternative TCRs or other targeting moieties for application in tissue-specific autoimmune or inflammatory diseases.

A membrane-associated MHC-I inhibitory axis for cancer immune evasion

Immune-checkpoint blockade has revolutionized cancer treatment, but some cancers, such as acute myeloid leukemia (AML), do not respond or develop resistance. A potential mode of resistance is immune evasion of T cell immunity involving aberrant major histocompatibility complex class I (MHC-I) antigen presentation (AP). To map such mechanisms of resistance, we identified key MHC-I regulators using specific peptide-MHC-I-guided CRISPR-Cas9 screens in AML. The top-ranked negative regulators were surface protein sushi domain containing 6 (SUSD6), transmembrane protein 127 (TMEM127), and the E3 ubiquitin ligase WWP2. SUSD6 is abundantly expressed in AML and multiple solid cancers, and its ablation enhanced MHC-I AP and reduced tumor growth in a CD8+ T cell-dependent manner. Mechanistically, SUSD6 forms a trimolecular complex with TMEM127 and MHC-I, which recruits WWP2 for MHC-I ubiquitination and lysosomal degradation. Together with the SUSD6/TMEM127/WWP2 gene signature, which negatively correlates with cancer survival, our findings define a membrane-associated MHC-I inhibitory axis as a potential therapeutic target for both leukemia and solid cancers.

A chemically inducible IL-2 receptor signaling complex allows for effective in vitro and in vivo selection of engineered CD4+ T cells

Engineered T cells represent an emerging therapeutic modality. However, complex engineering strategies can present a challenge for enriching and expanding therapeutic cells at clinical scale. In addition, lack of in vivo cytokine support can lead to poor engraftment of transferred T cells, including regulatory T cells (Treg). Here, we establish a cell-intrinsic selection system that leverages the dependency of primary T cells on IL-2 signaling. FRB-IL2RB and FKBP-IL2RG fusion proteins were identified permitting selective expansion of primary CD4+ T cells in rapamycin supplemented medium. This chemically inducible signaling complex (CISC) was subsequently incorporated into HDR donor templates designed to drive expression of the Treg master regulator FOXP3. Following editing of CD4+ T cells, CISC+ engineered Treg (CISC EngTreg) were selectively expanded using rapamycin and maintained Treg activity. Following transfer into immunodeficient mice treated with rapamycin, CISC EngTreg exhibited sustained engraftment in the absence of IL-2. Furthermore, in vivo CISC engagement increased the therapeutic activity of CISC EngTreg. Finally, an editing strategy targeting the TRAC locus permitted generation and selective enrichment of CISC+ functional CD19-CAR-T cells. Together, CISC provides a robust platform to achieve both in vitro enrichment and in vivo engraftment and activation, features likely beneficial across multiple gene-edited T cell applications.

Depression, anxiety and multiple sclerosis: Links with alexithymia

The aim of our study was to assess the prevalence of depression and anxiety in a population of patients treated for multiple sclerosis (MS) and their link with alexithymia.

Method

31 patients with MS according to McDonald's criteria, and followed in neurology department took part in the study. All patients were evaluated using a protocol to collect the epidemiological, clinical and evolution of the disease. We used versions of Arabized-Hospital Anxiety and Depression Scale (HADS) to assess the mood state and the Toronto Alexithymia Scale (TAS-20) for alexithymia.

Results and comments

Participants were divided on 18 women and 13 men with a mean age of 39 years. The prevalence of depression and anxiety were 42% and 52% respectively. The prevalence of alexithymia was 43%. The anxiety was correlated with the degree of disability and age of disease onset. Similarly, depression was more frequently observed in patients with higher EDSS, a long period of evolution. A positive correlation was found between alexithymia, depression and anxiety.

Our study showed that half of all MS patients have mood disorders. However, depression is the most common and most disabling psychiatric disorder in MS. The place of anxiety should not be neglected because in case of comorbidity with depression, can be an aggravating factor. The frequency of alexitymia is high and appears to be positively correlated with depression and anxiety.

SPG15 is the second most common cause of hereditary spastic paraplegia with thin corpus callosum

OBJECTIVE

Hereditary spastic paraplegias (HSPs) are very heterogeneous inherited neurodegenerative disorders. Our group recently identified ZFYVE26 as the gene responsible for one of the clinical and genetic entities, SPG15. Our aim was to describe its clinical and mutational spectra.

METHODS

We analyzed all exons of SPG15/ZFYVE26 gene by direct sequencing in a series of 60 non-SPG11 HSP subjects with associated mental or MRI abnormalities, including 30 isolated cases. The clinical data were collected through the SPATAX network.

RESULTS

We identified 13 novel truncating mutations in ZFYVE26, 12 of which segregated at the homozygous or compound heterozygous states in 8 new SPG15 families while 1 was found at the heterozygous state in a single family. Two of 3 splice site mutations were validated on mRNA of 2 patients. The SPG15 phenotype in 11 affected individuals was characterized by early onset HSP, severe progression of the disease, and mental impairment dominated by cognitive decline. Thin corpus callosum and white matter hyperintensities were MRI hallmarks of the disease in this series.

CONCLUSIONS

The mutations are truncating, private, and distributed along the entire coding sequence of ZFYVE26, which complicates the analysis of this gene in clinical practice. In our series of patients with hereditary spastic paraplegia-thin corpus callosum, the largest analyzed so far, SPG15 was the second most frequent form (11.5%) after SPG11. Both forms share similar clinical and imaging presentations with very few distinctions, which are, however, insufficient to infer the molecular diagnosis when faced with a single patient.

Tunisian hereditary spastic paraplegias: clinical variability supported by genetic heterogeneity

Hereditary spastic paraplegias (HSP) constitute a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by slowly progressive spasticity of the lower extremities. We performed the first clinical, epidemiological and genetic study of HSP in Southern Tunisia. We investigated 88 patients belonging to 38 unrelated Tunisian HSP families. We could establish the minimal prevalence of HSP in the district of Sfax at 5.75/100,000. Thirty-one percent of the families had a pure HSP, whereas 69% had a complicated form. The mode of inheritance was almost exclusively compatible with an autosomal recessive trait (97%, 37/38). Taking into account previously published results and new data generated in this work, genetic studies revealed significant or putative linkage to known HSP loci in 13 families (34.2%) to either SPG11 (7/38, 18.4%), SPG15 (4/38, 10.5%) or to SPG4 and SPG5 in one family each. The linkage results could be validated through the identification of two recurrent truncating mutations (R2034X and M245VfsX246) in the SPG11 gene, three different mutations (Q493X, F683LfsX685 and the novel S2004T/r.?) in the SPG15 gene, the recurrent R499C mutation in the SPG4 gene as well as the new R112X mutation in the SPG5 gene. SPG11 and SPG15 are the major responsible HSP genes in Tunisia.

Paraplégie spastique familiale avec amyotrophie sévère des mains (syndrome de Silver?)

Familial spastic paraplegia (FSP) with severe muscular atrophy of hands and feet is exceptional. Autosomal dominant forms were initially described by Silver in 1966. We report two cases, from the same Tunisian family, presenting FSP with severe amyotrophy of the hands. A brother and his sister, aged respectively 37 and 36 years old, presented practically the same clinical picture. Their parents were cousins. The female patient was hospitalized. Both patients developed gait disorders around the age of three years. Muscular atrophy of the hands arose much later, around the age of 20 years. The neurological examination disclosed a spastic gait with distal amyotrophy, severe in the hands and moderate in the feet. Sensitivity was preserved and there was no fasciculation. The spinal cord and cerebral MRI was normal. Electromyography (EMG) showed a neurogenic pattern in the distal muscles. Stimulation of the median, ulnar and sciatica nerves was ineffective. The somatosensory evoked potentials (EP) were delayed (upper limb) or desynchronised (lower limb). The auditory and visual EP were normal. The cerebrospinal fluid contained 1 mononuclear cell/mm3 and 10 mg protein/100 ml. Abnormalities of the cranio-vertebral junction, Arnold-Chiari malformation, syringomyelia and familial juvenile amyotrophic lateral sclerosis (ALS) were excluded and the diagnosis of Silver's syndrome was evoked.

[Primary pulmonary angiosarcoma]

Pulmonary angiosarcoma is an uncommon vascular and usually secondary tumor. Only a few primary cases of pulmonary angiosarcoma have been described. We report a case of primary pulmonary angiosarcoma in an adult man who presented with hemoptysis. Chest x-ray film and chest CT showed a right para-cardiac opacity associated with diffuse alveolar consolidation of the right basal lobe. Right inferior lobectomy has been performed. Pulmonary angiosarcoma was diagnosed on histological and immuno-histochemical studies of the operative specimen. The primitive character was retained after ruling out all other tumor localizations. The clinical outcome was rapidly fatal. This observation is added to the other rare cases published of primitive pulmonary angiosarcoma. It confirms the poor prognosis and the extremely hemorrhagic nature of this tumor. Isolated necrotic parenchymatous mass was an original radiological pattern observed in this patient.