Rapamycin Controls Lymphoproliferation and Reverses T-Cell Responses in a Patient with a Novel STIM1 Loss-of-Function Deletion.

PURPOSE: Deficiency of stromal interaction molecule 1 (STIM1) results in combined immunodeficiency accompanied by extra-immunological findings like enamel defects and myopathy. We here studied a patient with a STIM1 loss-of-function mutation who presented with severe lymphoproliferation. We sought to explore the efficacy of the mTOR inhibitor rapamycin in controlling disease manifestations and reversing aberrant T-cell subsets and functions, which has never been used previously in this disorder. METHODS: Clinical findings of the patient were collected over time. We performed immunological evaluations before and after initiation of rapamycin treatment, including detailed lymphocyte subset analyses, alterations in frequencies of circulating T follicular helper (cTFH) and regulatory T (Treg) cells and their subtypes as well as T cell activation and proliferation capacities. RESULTS: A novel homozygous exon 2 deletion in STIM1 was detected in a 3-year-old girl with severe lymphoproliferation, recurrent infections, myopathy, iris hypoplasia, and enamel hypoplasia. Lymphoproliferation was associated with severe T-cell infiltrates. The deletion resulted in a complete loss of protein expression, associated with a lack of store-operated calcium entry response, defective T-cell activation, proliferation, and cytokine production. Interestingly, patient blood contained fewer cTFH and increased circulating follicular regulatory (cTFR) cells. Abnormal skewing towards TH2-like responses in certain T-cell subpopulations like cTFH, non-cTFH memory T-helper, and Treg cells was associated with increased eosinophil numbers and serum IgE levels. Treatment with rapamycin controlled lymphoproliferation, improved T-cell activation and proliferation capacities, reversed T-cell responses, and repressed high IgE levels and eosinophilia. CONCLUSIONS: This study enhances our understanding of STIM1 deficiency by uncovering additional abnormal T-cell responses, and reveals for the first time the potential therapeutic utility of rapamycin for this disorder.

Diverse Clinical and Immunological Profiles in Patients with IPEX Syndrome: a Multicenter Analysis from Turkey.

PURPOSE: Immunodysregulation, Polyendocrinopathy, Enteropathy, and X-linked syndrome (IPEX), caused by pathogenic FOXP3 variants, is a rare autoimmune disorder with diverse clinical features, including early-onset diabetes, eczema, and enteropathy. Atypical cases show milder symptoms and unique signs, requiring different treatments. Therefore, there are ambiguities in the accurate diagnosis and management of IPEX. We sought to present clinical, genetic, and immunological assessments of 12 IPEX patients with long-term follow-up to facilitate the diagnosis and management of the disease. METHODS: Clinical findings and treatment options of the patients were collected over time. Lymphocyte subpopulations, protein expressions, regulatory T (Treg) and circulating T follicular helper (cTFH) cells, and T-cell proliferation were analyzed. RESULTS: Predominant presentations included autoimmunity (91.6%), failure to thrive (66.7%), and eczema (58.3%). There were four classical and eight atypical IPEX individuals. Allergic manifestations were more common in atypical patients. Notably, chronic diarrhea demonstrated heightened severity compared to other manifestations. Four patients (33.3%) demonstrated eosinophilia, and nine (75%) showed high serum IgE levels. Most patients exhibited normal percentages of Treg cells with reduced CD25, FOXP3, and CTLA-4 expressions, corrected after hematopoietic stem cell transplantation (HSCT). Compared to healthy controls, the TH2-like skewing accompanied by reduced TH17-like responses was observed in cTFH and Treg cells of patients. Overall, nine patients (75%) received immunosuppressants (ISs), and six (50%) underwent HSCT, which was the only treatment revealing sustained control. Sirolimus was used in six patients and showed better control than other ISs. CONCLUSIONS: The first cohort from Turkey with long-term follow-up results, comparing typical and atypical cases, provides insights into the outcomes of different therapeutic modalities and T- cell subtype changes in IPEX syndrome.

Expanding the clinical and immunological phenotypes of PAX1-deficient SCID and CID patients.

Paired box 1 (PAX1) deficiency has been reported in a small number of patients diagnosed with otofaciocervical syndrome type 2 (OFCS2). We described six new patients who demonstrated variable clinical penetrance. Reduced transcriptional activity of pathogenic variants confirmed partial or complete PAX1 deficiency. Thymic aplasia and hypoplasia were associated with impaired T cell immunity. Corrective treatment was required in 4/6 patients. Hematopoietic stem cell transplantation resulted in poor immune reconstitution with absent naïve T cells, contrasting with the superior recovery of T cell immunity after thymus transplantation. Normal ex vivo differentiation of PAX1-deficient CD34+ cells into mature T cells demonstrated the absence of a hematopoietic cell-intrinsic defect. New overlapping features with DiGeorge syndrome included primary hypoparathyroidism (n = 5) and congenital heart defects (n = 2), in line with PAX1 expression during early embryogenesis. Our results highlight new features of PAX1 deficiency, which are relevant to improving early diagnosis and identifying patients requiring corrective treatment.

Tau immunotherapy in Alzheimer's disease and progressive supranuclear palsy.

Tubulin-associated unit (tau) has been associated with more than 25 neurological disorders-the so-called tauopathies. Hence, finding a novel therapeutic agent targeting tau to halt the progression of diseases has been of interest. Alzheimer's disease (AD) and progressive supranuclear palsy (PSP) are the most studied tauopathies. AD is characterized by two cardinal pathological mechanisms: amyloid ß (Aß) plaques and neurofibrillary tangles (NFTs), leading to atrophy of the brain. Over the last few years, attention has been on NFTs composed of the hyperphosphorylated microtubule-associated protein tau. Tau contributes to the synaptic plasticity of axons; hyperphosphorylated and aggregated tau have been shown to increase the likelihood of cognitive impairments. PSP is also associated with tau accumulation in NFTs and neuropil threads, making this condition a candidate for tau-targeted therapies. Many tau-targeting therapies have been developed, and clinical trials are being conducted. Tau-targeting drugs are classified into four subgroups based on the pathological target: tau phosphorylation inhibitors, stabilizers of microtubules, enhancing tau clearance, and tau aggregation inhibitors. On the other hand, the desired specificity and sensitivity of tau immunotherapy agents without interrupting normal proteome are the fundamental point of tremendous attention. Starting with animal studies of these therapies to clinical trials, both are divided into passive and active immunotherapies, while passive immunotherapies are the method of desire. Targeting aggregation and phosphorylation sites of tau is the chief target of therapies. This article reviews the latest animal and clinical studies of tau-based immunotherapies and tau-targeted drugs for AD and PSP.