Deficiency of IKKß in neurons ameliorates Alzheimer's disease pathology in APP- and tau-transgenic mice.

In Alzheimer's disease (AD) brain, inflammatory activation regulates protein levels of amyloid-ß-peptide (Aß) and phosphorylated tau (p-tau), as well as neurodegeneration; however, the regulatory mechanisms remain unclear. We constructed APP- and tau-transgenic AD mice with deletion of IKKß specifically in neurons, and observed that IKKß deficiency reduced cerebral Aß and p-tau, and modified inflammatory activation in both AD mice. However, neuronal deficiency of IKKß decreased apoptosis and maintained synaptic proteins (e.g., PSD-95 and Munc18-1) in the brain and improved cognitive function only in APP-transgenic mice, but not in tau-transgenic mice. Additionally, IKKß deficiency decreased BACE1 protein and activity in APP-transgenic mouse brain and cultured SH-SY5Y cells. IKKß deficiency increased expression of PP2A catalytic subunit isoform A, an enzyme dephosphorylating cerebral p-tau, in the brain of tau-transgenic mice. Interestingly, deficiency of IKKß in neurons enhanced autophagy as indicated by the increased ratio of LC3B-II/I in brains of both APP- and tau-transgenic mice. Thus, IKKß deficiency in neurons ameliorates AD-associated pathology in APP- and tau-transgenic mice, perhaps by decreasing Aß production, increasing p-tau dephosphorylation, and promoting autophagy-mediated degradation of BACE1 and p-tau aggregates in the brain. However, IKKß deficiency differently protects neurons in APP- and tau-transgenic mice. Further studies are needed, particularly in the context of interaction between Aß and p-tau, before IKKß/NF-κB can be targeted for AD therapies.

P38α-MAPK phosphorylates Snapin and reduces Snapin-mediated BACE1 transportation in APP-transgenic mice.

Amyloid ß peptide (Aß) is the major pathogenic molecule in Alzheimer's disease (AD). BACE1 enzyme is essential for the generation of Aß. Deficiency of p38α-MAPK in neurons increases lysosomal degradation of BACE1 and decreases Aß deposition in the brain of APP-transgenic mice. However, the mechanisms mediating effects of p38α-MAPK are largely unknown. In this study, we used APP-transgenic mice and cultured neurons and observed that deletion of p38α-MAPK specifically in neurons decreased phosphorylation of Snapin at serine, increased retrograde transportation of BACE1 in axons and reduced BACE1 at synaptic terminals, which suggests that p38α-MAPK deficiency promotes axonal transportation of BACE1 from its predominant locations, axonal terminals, to lysosomes in the cell body. In vitro kinase assay revealed that p38α-MAPK directly phosphorylates Snapin. By further performing mass spectrometry analysis and site-directed mutagenic experiments in SH-SY5Y cell lines, we identified serine residue 112 as a p38α-MAPK-phosphorylating site on Snapin. Replacement of serine 112 with alanine did abolish p38α-MAPK knockdown-induced reduction of BACE1 activity and protein level, and transportation to lysosomes in SH-SY5Y cells. Taken together, our study suggests that activation of p38α-MAPK phosphorylates Snapin and inhibits the retrograde transportation of BACE1 in axons, which might exaggerate amyloid pathology in AD brain.

Neuronal deficiency of p38α-MAPK ameliorates symptoms and pathology of APP or Tau-transgenic Alzheimer's mouse models.

Alzheimer's disease (AD) is the leading cause of dementia with very limited therapeutic options. Amyloid ß (Aß) and phosphorylated Tau (p-Tau) are key pathogenic molecules in AD. P38α-MAPK is specifically activated in AD lesion sites. However, its effects on AD pathogenesis, especially on p-Tau-associated brain pathology, and the underlying molecular mechanisms remain unclear. We mated human APP-transgenic mice and human P301S Tau-transgenic mice with mapk14-floxed and neuron-specific Cre-knock-in mice. We observed that deletion of p38α-MAPK specifically in neurons improves the cognitive function of both 9-month-old APP and Tau-transgenic AD mice, which is associated with decreased Aß and p-Tau load in the brain. We further used next-generation sequencing to analyze the gene transcription in brains of p38α-MAPK deficient and wild-type APP-transgenic mice, which indicated that deletion of p38α-MAPK regulates the transcription of calcium homeostasis-related genes, especially downregulates the expression of grin2a, a gene encoding NMDAR subunit NR2A. Cell culture experiments further verified that deletion of p38α-MAPK inhibits NMDA-triggered calcium influx and neuronal apoptosis. Our systemic studies of AD pathogenic mechanisms using both APP- and Tau-transgenic mice suggested that deletion of neuronal p38α-MAPK attenuates AD-associated brain pathology and protects neurons in AD pathogenesis. This study supports p38α-MAPK as a novel target for AD therapy.

Deficiency of Neuronal p38α MAPK Attenuates Amyloid Pathology in Alzheimer Disease Mouse and Cell Models through Facilitating Lysosomal Degradation of BACE1.

Amyloid ß (Aß) damages neurons and triggers microglial inflammatory activation in the Alzheimer disease (AD) brain. BACE1 is the primary enzyme in Aß generation. Neuroinflammation potentially up-regulates BACE1 expression and increases Aß production. In Alzheimer amyloid precursor protein-transgenic mice and SH-SY5Y cell models, we specifically knocked out or knocked down gene expression of mapk14, which encodes p38α MAPK, a kinase sensitive to inflammatory and oxidative stimuli. Using immunological and biochemical methods, we observed that reduction of p38α MAPK expression facilitated the lysosomal degradation of BACE1, decreased BACE1 protein and activity, and subsequently attenuated Aß generation in the AD mouse brain. Inhibition of p38α MAPK also enhanced autophagy. Blocking autophagy by treating cells with 3-methyladenine or overexpressing dominant-negative ATG5 abolished the deficiency of the p38α MAPK-induced BACE1 protein reduction in cultured cells. Thus, our study demonstrates that p38α MAPK plays a critical role in the regulation of BACE1 degradation and Aß generation in AD pathogenesis.

Deficiency of IκB Kinase ß in Myeloid Cells Reduces Severity of Experimental Autoimmune Encephalomyelitis.

In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), peripherally developed myelin-reactive T lymphocytes stimulate myeloid cells (ie, microglia and infiltrated macrophages) to trigger an inflammatory reaction in the central nervous system, resulting in demyelination and neurodegeneration. IκB kinase ß (IKKß) is a kinase that modulates transcription of inflammatory genes. To investigate the pathogenic role of IKKß in MS, we developed strains in which IKKß was conditionally ablated in myeloid cells and established active or passive EAE in these animals. Deficiency of IKKß in myeloid cells ameliorated EAE symptoms and suppressed neuroinflammation, as shown by decreased infiltration of T lymphocytes and macrophages and reduced inflammatory gene transcription in the spinal cord at the peak or end stage of EAE. Myeloid deficiency of IKKß also reduced the transcription of Rorc or Il17 genes in T lymphocytes isolated from lymph nodes, spleen, and spinal cord of EAE mice. Moreover, cultured splenocytes isolated from myeloid IKKß-deficient EAE mice released less IL-17, interferon-γ, and granulocyte-macrophage colony-stimulating factor after treatment with myelin peptide than splenocytes from IKKß wild-type EAE mice. Thus, deficiency of myeloid IKKß attenuates the severity of EAE by inhibiting both the neuroinflammatory activity and the activation of encephalitogenic T lymphocytes. These results suggest IKKß may be a potential target for MS patients, especially when neuroinflammation is the primary problem.

Impact of the COVID-19 Pandemic on Tumor Stage and Pathohistological Parameters of Vulvar Cancer.

Background/Objectives: Vulvar cancer (VC) comprises a small fraction of female neoplasms with notable high-incidence clusters among German regions. Despite a proposed impact of nationwide lockdowns in response to the COVID-19 pandemic on oncological diseases, the effect on VC staging and tumor characteristics remains yet to be resolved; therefore, analyzing pathological data from patients with squamous cell VC pre-, during, and post-COVID in a high-incidence region may offer insights into potential epidemiological and clinical trends. Methods: We identified a total of 90 patients who were diagnosed at the Institute of Pathology, University Hospital Saarland, between 2018 and 2023, and defined three distinct cohorts: a pre-COVID cohort (2018-2019), a COVID cohort (2020-2021), and a post-COVID cohort (2022-2023). Histomorphological data were collected from the individual patient reports and statistically analyzed using Fisher's exact test or the Kruskal-Wallis test. Results: Although we found no statistically significant differences in age, T-stage, perineural infiltration, blood vessel infiltration, resection status, grading, or resection margin between our three cohorts, surprisingly, we determined a greater extent of lymphovascular infiltration (Fisher's exact test; p = 0.041), as well as deeper tumor infiltration depth (Kruskal-Wallis test; p < 0.001) before the COVID-19 pandemic. Furthermore, we did not identify any soft indications of abnormalities in patient care within our center (unchanged status of the resection margins across all three cohorts). Conclusions: Our results clearly do not support a negative affection of clinical or pathobiological characteristics of VC during or after the pandemic. However, final assessments regarding the pandemic's effect on VC require additional study approaches in various regions, preferably with future extended timeframes of a longer follow-up.

p38α-MAPK-deficient myeloid cells ameliorate symptoms and pathology of APP-transgenic Alzheimer's disease mice.

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is pathologically characterized by extracellular deposition of amyloid-ß peptides (Aß) and microglia-dominated inflammatory activation in the brain. p38α-MAPK is activated in both neurons and microglia. How p38α-MAPK in microglia contributes to AD pathogenesis remains unclear. In this study, we conditionally knocked out p38α-MAPK in all myeloid cells or specifically in microglia of APP-transgenic mice, and examined animals for AD-associated pathologies (i.e., cognitive deficits, Aß pathology, and neuroinflammation) and individual microglia for their inflammatory activation and Aß internalization at different disease stages (e.g., at 4 and 9 months of age). Our experiments showed that p38α-MAPK-deficient myeloid cells were more effective than p38α-MAPK-deficient microglia in reducing cerebral Aß and neuronal impairment in APP-transgenic mice. Deficiency of p38α-MAPK in myeloid cells inhibited inflammatory activation of individual microglia at 4 months but enhanced it at 9 months. Inflammatory activation promoted microglial internalization of Aß. Interestingly, p38α-MAPK-deficient myeloid cells reduced IL-17a-expressing CD4-positive lymphocytes in 9 but not 4-month-old APP-transgenic mice. By cross-breeding APP-transgenic mice with Il-17a-knockout mice, we observed that IL-17a deficiency potentially activated microglia and reduced Aß deposition in the brain as shown in 9-month-old myeloid p38α-MAPK-deficient AD mice. Thus, p38α-MAPK deficiency in all myeloid cells, but not only in microglia, prevents AD progression. IL-17a-expressing lymphocytes may partially mediate the pathogenic role of p38α-MAPK in peripheral myeloid cells. Our study supports p38α-MAPK as a therapeutic target for AD patients.