Chlorpyrifos (CPF) biocide, exposure to which is mainly produced in the human population through diet, induces several neurotoxic effects. CPF single and repeated exposure induces memory and learning disorders, although the mechanisms that produce these outcomes are complex and not well understood. CPF treatment (single and repeated) of cholinergic septal SN56 cells induced an increase in phosphorylated-P38α levels that led to WNT/β-Catenin and NGF/P75^NTR/TrkA pathways disruption and cell death. These results provide new knowledge on the mechanisms that mediate CPF basal forebrain cholinergic neuronal loss induced by CPF single and repeated exposure and can help unravel the way through which this compound produces cognitive decline and develop efficient treatments against these effects.

Background: Perfluorooctane sulfonic acid (PFOS), a widely used industrial chemical, was reported to induce memory and learning process dysfunction. Some studies tried to reveal the mechanisms that mediate these effects, but how they are produced is still unknown. Basal forebrain cholinergic neurons (BFCN) maintain cognitive function and their selective neurodegeneration induces cognitive decline, as observed in Alzheimer’s disease. PFOS was reported to disrupt cholinergic and glutamatergic transmissions and thyroid hormone action, which regulate cognitive processes and maintain BFCN viability. Objective/Methods: To evaluate PFOS neurodegenerative effects on BFCN and the mechanisms that mediate them, SN56 cells (a neuroblastoma cholinergic cell line from the basal forebrain) were treated with PFOS (0.1 µM to 40 µM) with or without thyroxine (T3; 15 nM), MK-801 (20 µM) or acetylcholine (ACh; 10 µM). Results: In the present study, we found that PFOS treatment (1 or 14 days) decreased thyroid receptor α (TRα) activity by decreasing its protein levels and increased T3 metabolism through increased deiodinase 3 (D3) levels. Further, we observed that PFOS treatment disrupted cholinergic transmission by decreasing ACh content through decreased choline acetyltransferase (ChAT) activity and protein levels and through decreasing muscarinic receptor 1 (M1R) binding and protein levels. PFOS also disrupted glutamatergic transmission by decreasing glutamate content through increased glutaminase activity and protein levels and through decreasing N-methyl-D-aspartate receptor subunit 1 (NMDAR1); effects mediated through M1R disruption. All these effects were mediated through decreased T3 activity and T3 supplementation partially restored to the normal state. Conclusions: These findings may assist in understanding how PFOS induces neurodegeneration, and the mechanisms involved, especially in BFCN, to explain the process that could lead to cognitive dysfunction and provide new therapeutic tools to treat and prevent its neurotoxic effects.

Neuroendocrine carcinomas (NECs) of the head and neck (HN) account for <1% of HN cancers (HNCs), with a 5-year overall survival (OS) <20%. This is a retrospective study of HN NECs diagnosed at our institution between 2005 and 2022. Immunohistochemistry and next-generation sequencing (NGS) were used to evaluate neuroendocrine markers, tumor mutational burden (TMB), mutational profiles and T-cell receptor repertoires. Eleven patients with high-grade HN NECs were identified (male:female ratio 6:5; median age 61 (Min–Max: 31–86)): nasoethmoidal (3), parotid gland (3), submaxillary gland (1), larynx (3) and base of tongue (1). Among n = 8 stage II/IVA/B, all received (chemo)radiotherapy with/without prior surgery or induction chemotherapy, with complete response in 7/8 (87.5%). Among n = 6 recurrent/metastatic patients, three received anti-PD1 (nivolumab (2), pembrolizumab (1)): two achieved partial responses lasting 24 and 10 months. After a median follow-up of 30 and 23.5 months since diagnosis and since recurrent/metastatic, median OS was not reached. Median TMB (n = 7) was 6.72 Mut/Mb. The most common pathogenic variants were TP53, HNF1A, SMARCB1, CDKN2A, PIK3CA, RB1 and MYC. There were 224 median TCR clones (n = 5 pts). In one patient, TCR clones increased from 59 to 1446 after nivolumab. HN NECs may achieve long-lasting survival with multimodality treatment. They harbor moderate-high TMBs and large TCR repertoires, which may explain responses to anti-PD1 agents in two patients and justify the study of immunotherapy in this disease.

Butylparaben (BP), a widely used preservative, was implicated in cognitive impairment, though its neurotoxic mechanisms remain elusive. Basal forebrain cholinergic neurons (BFCN) are selectively lost in dementias, contributing to cognitive decline. To explore different mechanisms related with BFCN loss, we employed BF SN56 cholinergic wild-type or silenced cells for Tau, amyloid-beta precursor protein (βApp), acetylcholinesterase (AChE), or glycogen synthase kinase-3 beta (GSK3β) genes, exposing them to BP (0.1–80 µM) for 1 or 14 days alongside triiodothyronine (T3; 15 nM), N-acetylcysteine (NAC; 1 mM), or recombinant heat shock protein 70 (rHSP70; 30 µM). BP disrupted cholinergic transmission by AChE inhibition and provoked cell death through thyroid hormones (THs) pathway disruption, Aβ/p-Tau protein accumulation, AChE-S overexpression, and oxidative stress (OS). Aβ/p-Tau accumulation was correlated with HSP70 downregulation, OS exacerbation, and GSK3β hyperactivation (for p-Tau). BP-induced OS was mediated by reactive oxygen species (ROS) overproduction and nuclear factor erythroid 2-related factor 2 (NRF2) pathway disruption. All observed effects were contingent upon TH signaling impairment. These findings uncover novel mechanistic links between BP exposure and BFCN neurodegeneration, providing a framework for therapeutic strategies.

Background/Objectives: Perfluorooctane sulfonic acid (PFOS), a persistent industrial chemical, has been associated with impairments in cognition. While several studies have attempted to identify the underlying mechanisms, the precise pathways mediating these cognitive deficits remain incompletely understood. PFOS induces cell death in basal forebrain cholinergic neurons (BFCNs), a population critically involved in maintaining cognitive function, partially through the disruption of thyroid hormone signaling. These neurotoxic effects could be mediated through multiple interconnected pathways, including the generation of oxidative stress, dysregulation of prostaglandin E2 (PGE2) signaling, and disruption of nerve growth factor (NGF) homeostasis, all of which have been independently linked to BFCN degeneration and cognitive dysfunction and reported to be induced after PFOS exposure. Methods: To systematically evaluate PFOS-induced neurodegeneration in BFCNs, we employed the SN56 cholinergic cell line derived from the basal forebrain. Cells were exposed to PFOS across a concentration range (0.1–40 μM) in combination with various pharmacological agents: triiodothyronine (T3; 15 nM), recombinant NGF (20 μM), MF-63 (1 μM), and N-acetylcysteine (1 mM). Results: Our experimental results show that PFOS exposure (both single 1-day and repeated 14-day treatments) triggers oxidative stress through reactive oxygen species accumulation coupled with diminished NRF2 pathway activity. Furthermore, PFOS disrupts both PGE2 signaling and the NGF/TrkA/P75^NTR neurotrophic pathways, ultimately leading to BFCN cell death. These neurotoxic effects appear to be partially mitigated through T3 treatment, among other mechanisms. Conclusions: These findings provide valuable mechanistic insights into PFOS-induced BFCN neurodegeneration and the consequent cognitive decline while simultaneously suggesting potential therapeutic strategies to counteract these detrimental effects.