Glycosphingolipids

H3K27M-mutant diffuse midline gliomas (DMGs) express high levels of the disialoganglioside GD2 (ref. 1). Chimeric antigen receptor-modified T cells targeting GD2 (GD2-CART) eradicated DMGs in preclinical models1. Arm A of Phase I trial no. NCT04196413 (ref. 2) administered one intravenous (IV) dose of autologous GD2-CART to patients with H3K27M-mutant pontine (DIPG) or spinal DMG (sDMG) at two dose levels (DL1, 1 × 106 kg-1; DL2, 3 × 106 kg-1) following lymphodepleting chemotherapy. Patients with clinical or imaging benefit were eligible for subsequent intracerebroventricular (ICV) intracranial infusions (10-30 × 106 GD2-CART). Primary objectives were manufacturing feasibility, tolerability and the identification of maximally tolerated IV dose. Secondary objectives included preliminary assessments of benefit. Thirteen patients enroled, with 11 receiving IV GD2-CART on study (n = 3 DL1 (3 DIPG); n = 8 DL2 (6 DIPG, 2 sDMG)). GD2-CART manufacture was successful for all patients. No dose-limiting toxicities occurred on DL1, but three patients experienced dose-limiting cytokine release syndrome on DL2, establishing DL1 as the maximally tolerated IV dose. Nine patients received ICV infusions, with no dose-limiting toxicities. All patients exhibited tumour inflammation-associated neurotoxicity, safely managed with intensive monitoring and care. Four patients demonstrated major volumetric tumour reductions (52, 54, 91 and 100%), with a further three patients exhibiting smaller reductions. One patient exhibited a complete response ongoing for over 30 months since enrolment. Nine patients demonstrated neurological benefit, as measured by a protocol-directed clinical improvement score. Sequential IV, followed by ICV GD2-CART, induced tumour regressions and neurological improvements in patients with DIPG and those with sDMG.

Although senescent cells can be eliminated by the immune system, they tend to accumulate with age in various tissues. Here we show that senescent cells can evade immune clearance by natural killer (NK) cells by upregulating the expression of the disialylated ganglioside GD3 at their surface. The increased level of GD3 expression on senescent cells that naturally occurs upon aging in liver, lung, kidney or bones leads to a strong suppression of NK-cell-mediated immunosurveillance. In mice, we found that targeting GD3+ senescent cells with anti-GD3 immunotherapy attenuated the development of experimentally induced or age-related lung and liver fibrosis and age-related bone remodeling. These results demonstrate that GD3 upregulation confers immune privilege to senescent cells. We propose that GD3 acts as a senescence immune checkpoint (SIC) that allows senescent cells to escape immunosurveillance and to trigger immune anergy during aging.

As tissue-resident macrophages of the central nervous system parenchyma, microglia perform diverse essential functions during homeostasis and perturbations1. They primarily interact with neurons by means of synaptic engulfment and through the rapid elimination of apoptotic cells and non-functional synapses2. Here, by combining unbiased lipidomics and high-resolution spatial lipid imaging, deep single-cell transcriptome analysis and novel cell-type-specific mutants, we identified a previously unknown mode of microglial interaction with neurons. During homeostasis, microglia deliver the lysosomal enzyme β-hexosaminidase to neurons for the degradation of the ganglioside GM2 that is integral to maintaining cell membrane organization and function. Absence of Hexb, encoding the β subunit of β-hexosaminidase, in both mice and patients with neurodegenerative Sandhoff disease leads to a massive accumulation of GM2 derivatives in a characteristic spatiotemporal manner3. In mice, neuronal GM2 gangliosides subsequently engage the macrophage galactose-type lectin 2 receptor on microglia through N-acetylgalactosamine residues, leading to lethal neurodegeneration. Notably, replacement of microglia with peripherally derived microglia-like cells is able to break this degenerative cycle and fully restore central nervous system homeostasis. Our results reveal a mode of bidirectional microglia-neuron communication centred around GM2 ganglioside turnover, identify a microgliopathy and offer therapeutic avenues for these maladies.

Amyotrophic Lateral Sclerosis (ALS) is a progressive and fatal condition marked by the degeneration of motor neurons. ALS has been linked to numerous genes with diverse biological roles, reflecting a highly intricate and multifaceted disease process. This diversity poses significant challenges in developing universally effective and bioavailable treatments. Advancing therapeutic strategies require uncovering molecular pathways that are major drivers of ALS. We conducted proteomic analyses of human iPSC-derived motor neurons carrying C9ORF72 mutations, alongside spinal ventral horns from mice with pathogenic C9orf72-mutations. This cross-species approach revealed disruptions in synaptic vesicle release, endoplasmic reticulum (ER) and mitochondrial stress responses as conserved ALS pathogenic mechanisms. Disease progression was associated with accumulation of cytotoxic protein aggregates and oxidative stress. We analyzed the potential of GM1, an established neuroprotective molecule, to reverse these pathogenic features. To enhance the pharmacokinetics of GM1, we developed Talineuren (TLN), a nanoliposome-based formulation of the active pharmaceutical ingredient GM1 ganglioside that improves its bioavailability. GM1 stabilized mitochondrial Ca2⁺ handling, improved energy metabolism, and alleviated ER stress, preventing protein aggregation and restoring cellular proteostasis and counteracted behavioral deficits in C9orf72 and SOD1-G93A mouse models. Together, these findings underscore the central, convergent role for cellular disruptions in ALS and position TLN as a promising therapeutic candidate.