Amplification of neurotoxic HTTex1 assemblies in human neurons.

Huntington's disease (HD) is a genetically inherited neurodegenerative disorder caused by expansion of a polyglutamine (polyQ) repeat in the exon-1 of huntingtin protein (HTT). The expanded polyQ enhances the amyloidogenic propensity of HTT exon 1 (HTTex1), which forms a heterogeneous mixture of assemblies with a broad neurotoxicity spectrum. While predominantly intracellular, monomeric and aggregated mutant HTT species are also present in the cerebrospinal fluids of HD patients, however, their biological properties are not well understood. To explore the role of extracellular mutant HTT in aggregation and toxicity, we investigated the uptake and amplification of recombinant HTTex1 assemblies in cell culture models. We find that small HTTex1 fibrils preferentially enter human neurons and trigger the amplification of neurotoxic assemblies; astrocytes or epithelial cells are not permissive. The amplification of HTTex1 in neurons depletes endogenous HTT protein with non-pathogenic polyQ repeat, activates apoptotic caspase-3 pathway and induces nuclear fragmentation. Using a panel of novel monoclonal antibodies and genetic mutation, we identified epitopes within the N-terminal 17 amino acids and proline-rich domain of HTTex1 to be critical in neural uptake and amplification. Synaptosome preparations from the brain homogenates of HD mice also contain mutant HTT species, which enter neurons and behave similar to small recombinant HTTex1 fibrils. These studies suggest that amyloidogenic extracellular mutant HTTex1 assemblies may preferentially enter neurons, propagate and promote neurodegeneration.

Identification of distinct conformations associated with monomers and fibril assemblies of mutant huntingtin.

The N-terminal fragments of mutant huntingtin (mHTT) misfold and assemble into oligomers, which ultimately bundle into insoluble fibrils. Conformations unique to various assemblies of mHTT remain unknown. Knowledge on the half-life of various multimeric structures of mHTT is also scarce. Using a panel of four new antibodies named PHP1-4, we have identified new conformations in monomers and assembled structures of mHTT. PHP1 and PHP2 bind to epitopes within the proline-rich domain (PRD), whereas PHP3 and PHP4 interact with motifs formed at the junction of polyglutamine (polyQ) and polyproline (polyP) repeats of HTT. The PHP1- and PHP2-reactive epitopes are exposed in fibrils of mHTT exon1 (mHTTx1) generated from recombinant proteins and mHTT assemblies, which progressively accumulate in the nuclei, cell bodies and neuropils in the brains of HD mouse models. Notably, electron microscopic examination of brain sections of HD mice revealed that PHP1- and PHP2-reactive mHTT assemblies are present in myelin sheath and in vesicle-like structures. Moreover, PHP1 and PHP2 antibodies block seeding and subsequent fibril assembly of mHTTx1 in vitro and in a cell culture model of HD. PHP3 and PHP4 bind to epitopes in full-length and N-terminal fragments of monomeric mHTT and binding diminishes as the mHTTx1 assembles into fibrils. Interestingly, PHP3 and PHP4 also prevent the aggregation of mHTTx1 in vitro highlighting a regulatory function for the polyQ-polyP motifs. These newly detected conformations may affect fibril assembly, stability and intercellular transport of mHTT.

IKKß and mutant huntingtin interactions regulate the expression of IL-34: implications for microglial-mediated neurodegeneration in HD.

Neuronal interleukin-34 (IL-34) promotes the expansion of microglia in the central nervous system-microglial activation and expansion are in turn implicated in the pathogenesis of Huntington's disease (HD). We thus examined whether the accumulation of an amyloidogenic exon-1 fragment of mutant huntingtin (mHTTx1) modulates the expression of IL-34 in dopaminergic neurons derived from a human embryonic stem cell line. We found that mHTTx1 aggregates induce IL-34 production selectively in post-mitotic neurons. Exposure of neurons to DNA damaging agents or the excitotoxin NMDA elicited similar results suggesting that IL-34 induction may be a general response to neuronal stress including the accumulation of misfolded mHTTx1. We further determined that knockdown or blocking the activity of IκB kinase beta (IKKß) prevented the aggregation of mHTTx1 and subsequent IL-34 production. While elevated IL-34 itself had no effect on the aggregation or the toxicity of mHTTx1 in neuronal culture, IL-34 expression in a rodent brain slice model with intact neuron-microglial networks exacerbated mHTTx1-induced degeneration of striatal medium-sized spiny neurons. Conversely, an inhibitor of the IL-34 receptor reduced microglial numbers and ameliorated mHTTx1-mediated neurodegeneration. Together, these findings uncover a novel function for IKKß/mHTTx1 interactions in regulating IL-34 production, and implicate a role for IL-34 in non-cell-autonomous, microglial-dependent neurodegeneration in HD.

Base excision repair and double strand break repair cooperate to modulate the formation of unrepaired double strand breaks in mouse brain.

We lack the fundamental information needed to understand how DNA damage in the brain is generated and how it is controlled over a lifetime in the absence of replication check points. To address these questions, here, we integrate cell-type and region-specific features of DNA repair activity in the normal brain. The brain has the same repair proteins as other tissues, but normal, canonical repair activity is unequal and is characterized by high base excision repair (BER) and low double strand break repair (DSBR). The natural imbalance creates conditions where single strand breaks (SSBs) can convert to double strand breaks (DSBs) and reversibly switch between states in response to oxidation both in vivo and in vitro. Our data suggest that, in a normal background of repair, SSBs and DSBs are in an equilibrium which is pushed or pulled by metabolic state. Interconversion of SSB to DSBs provides a physiological check point, which would allow the formation of unrepaired DSBs for productive functions, but would also restrict them from exceeding tolerable limits.

Clinical and neurocognitive profiles of subjects at high risk for psychosis with and without obsessive-compulsive symptoms.

OBJECTIVE: Obsessive-compulsive symptoms (OCS), which are common in psychotic-spectrum illnesses, are of clinical interest because of their association with poor prognosis or cognitive dysfunction. However, few studies on the clinical and neurocognitive implications of OCS in individuals at ultra-high risk for psychosis (UHR) have been conducted. METHOD: Sixty-five UHR subjects [24 with OCS (UHR+OCS), 41 without OCS (UHR-OCS)], and 40 healthy controls were assessed using clinical scales and neurocognitive tests. RESULTS: Those with UHR+OCS showed more severe clinical symptoms and poorer global functioning as compared to both healthy controls and the UHR-OCS group, according to the results of the Global Assessment of Functioning, the Comprehensive Assessment of At-Risk Mental States, and the Positive and Negative Syndrome Scale (total, negative, and general scores). In the neurocognitive domain, those in the UHR-OCS group showed notably greater latency in the Stroop task and more confabulation errors in immediate recall in the Rey-Osterrieth Complex Figure Test compared with those in UHR+OCS group, whose performance levels were similar to those of the healthy control group. CONCLUSIONS: The OCS manifested in UHR individuals was associated with a more severe clinical symptomatic presentation, including lower global functioning and more psychotic symptoms. On the other hand, those with UHR-OCS performed more poorly on some cognitive tests. The features that distinguish the groups can be used for developing prognoses and intervention strategies for the heterogeneous UHR group.

Gut Bacteria Regulate the Pathogenesis of Huntington's Disease in Drosophila Model.

Changes in the composition of gut microbiota are implicated in the pathogenesis of several neurodegenerative disorders. Here, we investigated whether gut bacteria affect the progression of Huntington's disease (HD) in transgenic Drosophila melanogaster (fruit fly) models expressing full-length or N-terminal fragments of human mutant huntingtin (HTT) protein. We find that elimination of commensal gut bacteria by antibiotics reduces the aggregation of amyloidogenic N-terminal fragments of HTT and delays the development of motor defects. Conversely, colonization of HD flies with Escherichia coli (E. coli), a known pathobiont of human gut with links to neurodegeneration and other morbidities, accelerates HTT aggregation, aggravates immobility, and shortens lifespan. Similar to antibiotics, treatment of HD flies with small compounds such as luteolin, a flavone, or crocin a beta-carotenoid, ameliorates disease phenotypes, and promotes survival. Crocin prevents colonization of E. coli in the gut and alters the levels of commensal bacteria, which may be linked to its protective effects. The opposing effects of E. coli and crocin on HTT aggregation, motor defects, and survival in transgenic Drosophila models support the involvement of gut-brain networks in the pathogenesis of HD.

Corrigendum: Gut bacteria regulate the pathogenesis of Huntington's disease in Drosophila model.

[This corrects the article DOI: 10.3389/fnins.2022.902205.].

Peroxisome proliferator-activated receptor γ agonist suppresses human telomerase reverse transcriptase expression and aromatase activity in eutopic endometrial stromal cells from endometriosis.

OBJECTIVE: To investigate the effect of peroxisome proliferator activated receptor γ (PPARγ) agonist on the cell proliferation properties and expression of human telomerase reverse transcriptase (hTERT) and aromatase in cultured endometrial stromal cell (ESC) from patients with endometriosis. METHODS: Human endometrial tissues were obtained from women with endometriosis and healthy women (controls) using endometrial biopsy. Isolated ESCs were cultured and the cell proliferation was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay and expression of hTERT, aromatase, and cyclooxygenase (COX)-2 by western blotting according to the addition of rosiglitazone (PPARγ agonist). RESULTS: We demonstrate that the cultured ESCs of endometriosis showed hTERT protein overexpression and increased cellular proliferation, which was inhibited by rosiglitazone, in a dose-dependent manner. At the same time, PPARγ agonist also inhibited aromatase and COX-2 expression, resulting in decreased prostaglandin E2 production in the ESCs of endometriosis. CONCLUSION: This study suggests that PPARγ agonist plays an inhibitory role in the proliferative properties of eutopic endometrium with endometriosis by down-regulation of hTERT and COX-2 expression; this could be a new treatment target for endometriosis.

[Sigmoidovesical fistula caused by diverticulitis detected with sigmoidoscopy].

Enterovesical fistular is an abnormal communication between the intestine and the bladder. It represents a rare complication of intestinal diverticulitis, colorectal malignancy, bladder cancer, inflammatory bowel disease, radiotherapy, and trauma. The most common etiology is diverticular disease. A 70-year-old man came to our hospital due to frequent urinary tract infection, dysuria, pneumaturia and fecaluria. Sigmoidoscopy revealed a large diverticulum with impacted stool at the sigmoid colon. When the scope was inserted into the site, the patient complained of severe urgency and pneumaturia. CT scan was performed. 1.5 cm sized fistular tract between the sigmoid colon and bladder was noted. According to the endoscopy and CT finding, the diagnosis of colovesical fistula was made. The patient underwent surgical intervention. At laparotomy, there were multiple diverticula and fistular tract was noted.

Clinical characteristics of obese boys and girls in a high school: focused on abdominal fat indices, fatty liver and carotid intima-media thickness.

PURPOSE: Our study aimed to evaluated sex differences in clinical features of obese high school students. METHODS: One hundred three obese high school students (body mass index [BMI]≥85th percentile) and 51 control students (BMI<85th percentile) were enrolled in this study. Anthropometric measurements were performed. Fasting serum glucose, insulin, aspartate aminotransferase, alanine aminotransferase, total cholesterol, triglyceride, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and high-sensitive C-reactive protein were measured. Abdominal fat thickness, degree of fatty liver, and carotid intima-media thickness were measured by ultrasound. RESULTS: In control and obese groups, waist circumference was significantly longer in boys but body fat mass was significantly higher in girls. In the control group, total cholesterol and LDL-C were higher in girls. In the obese group, however, aspartate aminotransferase, alanine aminotransferase and triglyceride were higher and HDL-C was lower in boys. Preperitoneal fat thickness was significantly higher in obese girls. In obese group, the degree of fatty liver was significantly higher in boys. Carotid intima-media thickness was not significantly different between boys and girls. CONCLUSION: Obese adolescents had distinguishable sex differences in body measurements, metabolic abnormalities, abdominal fat thickness and fatty liver. We can infer that these characteristics may extend into adult obesity.