Darier disease (DD) is a rare, inherited multi-organ disorder associated with mutations in the ATP2A2 gene. DD patients often have skin involvement characterized by malodorous, inflamed skin and recurrent, severe infections. Therapeutic options are limited and inadequate for the long-term management of this chronic disease. The aim of this study was to characterize the cutaneous immune infiltrate in DD skin lesions in detail and to identify new therapeutic targets. Using gene and protein expression profiling assays including scRNA sequencing, we demonstrate enhanced expression of Th17-related genes and cytokines and increased numbers of Th17 cells in six DD patients. We provide evidence that targeting the IL-17/IL-23 axis in a case series of three DD patients with monoclonal antibodies is efficacious with significant clinical improvement. As DD is a chronic, relapsing disease, our findings might pave the way toward additional options for the long-term management of skin inflammation in patients with DD.

Subpial demyelination is a specific hallmark of multiple sclerosis and a correlate of disease progression. Although the mechanism(s) that mediate pathogenesis in the subpial compartment remain unclear, it has been speculated that inflammation in the overlying meninges may be associated with subpial injury. Here we show that adoptive transfer of proteolipid protein–primed Th17 cells into SJL/J recipient mice induces subpial demyelination associated with microglial/macrophage activation, disruption of the glial limitans, and evidence of an oxidative stress response. This pathology was topologically associated with foci of immune cells in the meninges and occurred in the absence of measurable anti–myelin oligodendrocyte glycoprotein IgM or IgG antibodies. To test the role of brain-infiltrating leukocytes on subpial injury, we modulated sphingosine 1-phosphate (S1P) receptor _1,5 activity with BAF312 (siponimod) treatment. Administration of BAF312, even after adoptively transferred T cells had entered the brain, significantly ameliorated clinical experimental autoimmune encephalomyelitis and diminished subpial pathology, concomitant with a selective reduction in the capacity of transferred T cells to make Th17 cytokines. We conclude that sustained subpial cortical injury is associated with the capacity for brain-resident T cells to produce Th17 cytokines, and this pathological process occurs in an S1P receptor _1,5 –dependent manner.

People living with multiple sclerosis (MS) experience episodic CNS white matter lesions instigated by autoreactive T cells. With age, patients with MS show evidence of gray matter demyelination and experience devastating nonremitting symptomology. What drives progression is unclear and studying this has been hampered by the lack of suitable animal models. Here, we show that passive experimental autoimmune encephalomyelitis (EAE) induced by an adoptive transfer of young Th17 cells induced a nonremitting clinical phenotype that was associated with persistent leptomeningeal inflammation and cortical pathology in old, but not young, SJL/J mice. Although the quantity and quality of T cells did not differ in the brains of old versus young EAE mice, an increase in neutrophils and a decrease in B cells were observed in the brains of old mice. Neutrophils were also found in the leptomeninges of a subset of progressive MS patient brains that showed evidence of leptomeningeal inflammation and subpial cortical demyelination. Taken together, our data show that while Th17 cells initiate CNS inflammation, subsequent clinical symptoms and gray matter pathology are dictated by age and associated with other immune cells, such as neutrophils.

Type 1 diabetes (T1D) is a multifactorial autoimmune disorder where pancreatic beta cells are lost before the clinical manifestations of the disease. Administration of mesenchymal stem cells (MSCs) or MSCs differentiated into insulin-producing cells (IPCs) have yielded limited success when used therapeutically. We have evaluated the immunoprophylactic potentials of precursors to insulin-producing cells (pIPCs) and IPCs in nonobese diabetic (NOD) mice to ask a basic question: do we need to differentiate MSCs into IPCs or will pIPCs suffice to attenuate autoimmune responses in T1D? Bone marrow-derived MSCs from Balb/c mice were characterized following the International Society for Cellular Therapy (ISCT) guidelines. MSCs cultured in high-glucose media for 11 to 13 passages were characterized for the expression of pancreatic lineage genes using real-time polymerase chain reaction. Expression of the PDX1 gene in pIPCs was assessed using Western blot and fluorescence-activated cell sorting (FACS). Triple-positive MSCs were differentiated into IPCs using a three-step protocol after sorting them for cell surface markers, i.e. CD29, CD44, and SCA-1. Nonobese diabetic mice were administered pIPCs, IPCs, or phosphate-buffered saline (PBS) into the tail vein at weeks 9 or 10 and followed-up for 29–30 weeks for fasting blood glucose levels. Two consecutive blood sugar levels of more than 250 mg/dl were considered diabetic. MSCs grown in high-glucose media for 11 to 13 passages expressed genes of the pancreatic lineage such as PDX1, beta2, neurogenin, PAX4, Insulin, and glucagon. Furthermore, Western blot and FACS analysis for PDX-1, a transcription factor necessary for beta cell maturation, confirmed that these cells were precursors of insulin-producing cells (pIPCs). NOD mice administered with pIPCs were better protected from developing diabetes with a protective efficacy of 78.4% (p < 0.009); however, administration of IPCs gave protective efficacy of 55% at the end of 28–30 weeks. Precursors to insulin-producing cells seem to have better potential to arrest autoimmune response in type 1 diabetes when administered before the onset of the disease in NOD mice. When translated to humans, autologous mesenchymal stem cells grown in high-glucose media for 10 to 13 passages may have beneficial effects in individuals at high risk of developing type 1 diabetes.

Genodermatoses represent a large group of inherited skin disorders encompassing clinically-heterogeneous conditions that manifest in the skin and other organs. Depending on disease variant, associated clinical manifestations and secondary complications can severely impact patients' quality of life and currently available treatments are transient and not curative. Multiple emerging approaches using CRISPR-based technologies offer promising prospects for therapy. Here, we explore current advances and challenges related to gene editing in rare skin diseases, including different strategies tailored to mutation type and structural organization of the affected gene, considerations for in vivo and ex vivo applications, the critical issue of delivery into the skin, and immune aspects of therapy. Against the backdrop of a landmark FDA approval for the first re-dosable gene replacement therapy for a rare genetic skin disorder, gene editing approaches are inching closer to the clinics and the possibility of a local permanent cure for patients affected by these disorders.