Now showing items 21-40 of 2974

    • Persistent False Positive Covid-19 Rapid Antigen Tests

      Herbert, Carly; McManus, David D; Soni, Apurv (2024-02-22)
      Rapid antigen tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are effective tools for the diagnosis of acute infection, particularly when used serially. The percentage of rapid antigen tests with false positive results is reported to be less than 1%. However, we have observed persons who repeatedly test positive with rapid antigen tests despite concurrent negative molecular tests; this infrequent phenomenon occurs predominantly among women and persons with autoimmune disorders.
    • Silencing Apoe with divalent-siRNAs improves amyloid burden and activates immune response pathways in Alzheimer's disease

      Ferguson, Chantal M; Hildebrand, Samuel; Godinho, Bruno M D C; Buchwald, Julianna; Echeverria, Dimas; Coles, Andrew; Grigorenko, Anastasia; Vangjeli, Lorenc; Sousa, Jacquelyn; McHugh, Nicholas; et al. (2024-02-20)
      Introduction: The most significant genetic risk factor for late-onset Alzheimer's disease (AD) is APOE4, with evidence for gain- and loss-of-function mechanisms. A clinical need remains for therapeutically relevant tools that potently modulate APOE expression. Methods: We optimized small interfering RNAs (di-siRNA, GalNAc) to potently silence brain or liver Apoe and evaluated the impact of each pool of Apoe on pathology. Results: In adult 5xFAD mice, siRNAs targeting CNS Apoe efficiently silenced Apoe expression and reduced amyloid burden without affecting systemic cholesterol, confirming that potent silencing of brain Apoe is sufficient to slow disease progression. Mechanistically, silencing Apoe reduced APOE-rich amyloid cores and activated immune system responses. Discussion: These results establish siRNA-based modulation of Apoe as a viable therapeutic approach, highlight immune activation as a key pathway affected by Apoe modulation, and provide the technology to further evaluate the impact of APOE silencing on neurodegeneration.
    • Domain-inlaid Nme2Cas9 adenine base editors with improved activity and targeting scope

      Bamidele, Nathan; Zhang, Han; Dong, Xiaolong; Cheng, Haoyang; Gaston, Nicholas; Feinzig, Hailey; Cao, Hanbing; Kelly, Karen; Watts, Jonathan K; Xie, Jun; et al. (2024-02-17)
      Nme2Cas9 has been established as a genome editing platform with compact size, high accuracy, and broad targeting range, including single-AAV-deliverable adenine base editors. Here, we engineer Nme2Cas9 to further increase the activity and targeting scope of compact Nme2Cas9 base editors. We first use domain insertion to position the deaminase domain nearer the displaced DNA strand in the target-bound complex. These domain-inlaid Nme2Cas9 variants exhibit shifted editing windows and increased activity in comparison to the N-terminally fused Nme2-ABE. We next expand the editing scope by swapping the Nme2Cas9 PAM-interacting domain with that of SmuCas9, which we had previously defined as recognizing a single-cytidine PAM. We then use these enhancements to introduce therapeutically relevant edits in a variety of cell types. Finally, we validate domain-inlaid Nme2-ABEs for single-AAV delivery in vivo.
    • Genome-wide kinetic profiling of pre-mRNA 3' end cleavage

      Torres Ulloa, Leslie; Calvo-Roitberg, Ezequiel; Pai, Athma A (2024-02-16)
      Cleavage and polyadenylation is necessary for the formation of mature mRNA molecules. The rate at which this process occurs can determine the temporal availability of mRNA for subsequent function throughout the cell and is likely tightly regulated. Despite advances in high-throughput approaches for global kinetic profiling of RNA maturation, genome-wide 3' end cleavage rates have never been measured. Here, we describe a novel approach to estimate the rates of cleavage, using metabolic labeling of nascent RNA, high-throughput sequencing, and mathematical modeling. Using in silico simulations of nascent RNA-seq data, we show that our approach can accurately and precisely estimate cleavage half-lives for both constitutive and alternative sites. We find that 3' end cleavage is fast on average, with half-lives under a minute, but highly variable across individual sites. Rapid cleavage is promoted by the presence of canonical sequence elements and an increased density of polyadenylation signals near a cleavage site. Finally, we find that cleavage rates are associated with the localization of RNA polymerase II at the end of a gene, and faster cleavage leads to quicker degradation of downstream readthrough RNA. Our findings shed light on the features important for efficient 3' end cleavage and the regulation of transcription termination.
    • Examining racial/ethnic inequities in treatment participation among perinatal individuals with depression

      Boama-Nyarko, Esther; Flahive, Julie; Zimmermann, Martha; Allison, Jeroan J.; Person, Sharina D.; Moore Simas, Tiffany A; Byatt, Nancy (2024-02-15)
      Objective: A cluster randomized controlled trial (RCT) of two interventions for addressing perinatal depression treatment in obstetric settings was conducted. This secondary analysis compared treatment referral and participation among Minoritized perinatal individuals compared to their non-Hispanic white counterparts. Methods: Among perinatal individuals with depression symptoms, we examined rates of treatment 1) referral (i.e., offered medications or referred to mental health clinician), 2) initiation (i.e., attended ≥1 mental health visit or reported prescribed antidepressant medication), and 3) sustainment (i.e., attended >1 mental health visit per study month or prescribed antidepressant medication at time of study interviews). We compared non-Hispanic white (NHW) (n = 149) vs. Minoritized perinatal individuals (Black, Asian, Hispanic/Latina, Pacific Islander, Native American, Multiracial, and white Hispanic/Latina n = 157). We calculated adjusted odds ratios (aOR) for each outcome. Results: Minoritized perinatal individuals across both interventions had significantly lower odds of treatment referral (aOR = 0.48;95% CI = 0.27-0.88) than their NHW counterparts. There were no statistically significant differences in the odds of treatment initiation (aOR = 0.64 95% CI:0.36-1.2) or sustainment (aOR = 0.54;95% CI = 0.28-1.1) by race/ethnicity. Conclusions: Perinatal mental healthcare inequities are associated with disparities in treatment referrals. Interventions focusing on referral disparities across race and ethnicity are needed.
    • Microglia-astrocyte crosstalk regulates synapse remodeling via Wnt signaling [preprint]

      Faust, Travis E; Lee, Yi-Han; O'Connor, Ciara; Boyle, Margaret A; Gunner, Georgia; Badimon, Ana; Ayata, Pinar; Schaefer, Anne; Schafer, Dorothy P (2024-02-09)
      Astrocytes and microglia are emerging key regulators of activity-dependent synapse remodeling that engulf and remove synapses in response to changes in neural activity. Yet, the degree to which these cells communicate to coordinate this process remains an open question. Here, we use whisker removal in postnatal mice to induce activity-dependent synapse removal in the barrel cortex. We show that astrocytes do not engulf synapses in this paradigm. Instead, astrocytes reduce their contact with synapses prior to microglia-mediated synapse engulfment. We further show that reduced astrocyte-contact with synapses is dependent on microglial CX3CL1-CX3CR1 signaling and release of Wnts from microglia following whisker removal. These results demonstrate an activity-dependent mechanism by which microglia instruct astrocyte-synapse interactions, which then provides a permissive environment for microglia to remove synapses. We further show that this mechanism is critical to remodel synapses in a changing sensory environment and this signaling is upregulated in several disease contexts.
    • Clocks at sea: the genome-editing tide is rising

      Kwiatkowski, Erica R; Rosenthal, Joshua J C; Emery, Patrick (2024-02-08)
      The coastline is a particularly challenging environment for its inhabitants. Not only do they have to cope with the solar day and the passing of seasons, but they must also deal with tides. In addition, many marine species track the phase of the moon, especially to coordinate reproduction. Marine animals show remarkable behavioral and physiological adaptability, using biological clocks to anticipate specific environmental cycles. Presently, we lack a basic understanding of the molecular mechanisms underlying circatidal and circalunar clocks. Recent advances in genome engineering and the development of genetically tractable marine model organisms are transforming how we study these timekeeping mechanisms and opening a novel era in marine chronobiology.
    • Bigtools: a high-performance BigWig and BigBed library in Rust [preprint]

      Huey, Jack; Abdennur, Nezar (2024-02-08)
      The BigWig and BigBed file formats were originally designed for the visualization of next-generation sequencing data through a genome browser. Due to their versatility, these formats have long since become ubiquitous for the storage of processed sequencing data and regularly serve as the basis for downstream data analysis. As the number and size of sequencing experiments continues to accelerate, there is an increasing demand to efficiently generate and query BigWig and BigBed files in a scalable and robust manner, and to efficiently integrate these functionalities into data analysis environments and third-party applications. Here, we present Bigtools, a feature-complete, high-performance, and integrable software library for generating and querying both BigWig and BigBed files. Bigtools is written in the Rust programming language and includes a flexible suite of command line tools as well as bindings to Python. Bigtools is cross-platform and released under the MIT license. It is distributed on Crates.io and the Python Package Index, and the source code is available at https://github.com/jackh726/bigtools.
    • Microbiota encoded fatty-acid metabolism expands tuft cells to protect tissues homeostasis during infection in the large intestine [preprint]

      Kellogg, Tasia D; Ceglia, Simona; Mortzfeld, Benedikt M; Zeamer, Abigail L; Foley, Sage E; Ward, Doyle V; Bhattarai, Shakti K; McCormick, Beth A; Reboldi, Andrea; Bucci, Vanni (2024-01-31)
      Metabolic byproducts of the intestinal microbiota are crucial in maintaining host immune tone and shaping inter-species ecological dynamics. Among these metabolites, succinate is a driver of tuft cell (TC) differentiation and consequent type 2 immunity-dependent protection against invading parasites in the small intestine. Succinate is also a growth enhancer of the nosocomial pathogen Clostridioides difficile in the large intestine. To date, no research has shown the role of succinate in modulating TC dynamics in the large intestine, or the relevance of this immune pathway to C. difficile pathophysiology. Here we reveal the existence of a three-way circuit between commensal microbes, C. difficile and host epithelial cells which centers around succinate. Through selective microbiota depletion experiments we demonstrate higher levels of type 2 cytokines leading to expansion of TCs in the colon. We then demonstrate the causal role of the microbiome in modulating colonic TC abundance and subsequent type 2 cytokine induction using rational supplementation experiments with fecal transplants and microbial consortia of succinate-producing bacteria. We show that administration of a succinate-deficient Bacteroides thetaiotaomicron knockout (Δfrd) significantly reduces the enhanced type 2 immunity in mono-colonized mice. Finally, we demonstrate that mice prophylactically administered with the consortium of succinate-producing bacteria show reduced C. difficile-induced morbidity and mortality compared to mice administered with heat-killed bacteria or the vehicle. This effect is reduced in a partial tuft cell knockout mouse, Pou2f3+/-, and nullified in the tuft cell knockout mouse, Pou2f3-/-, confirming that the observed protection occurs via the TC pathway. Succinate is an intermediary metabolite of the production of short-chain fatty acids, and its concentration often increases during dysbiosis. The first barrier to enteric pathogens alike is the intestinal epithelial barrier, and host maintenance and strengthening of barrier integrity is vital to homeostasis. Considering our data, we propose that activation of TC by the microbiota-produced succinate in the colon is a mechanism evolved by the host to counterbalance microbiome-derived cues that facilitate invasion by intestinal pathogens.
    • Association of spatial proximity to fixed-site syringe services programs with HCV serostatus and injection equipment sharing practices among people who inject drugs in rural New England, United States

      Romo, Eric; Stopka, Thomas J; Jesdale, Bill M; Wang, Bo; Mazor, Kathleen M; Friedmann, Peter D (2024-01-28)
      Background: Hepatitis C virus (HCV) disproportionately affects rural communities, where health services are geographically dispersed. It remains unknown whether proximity to a syringe services program (SSP) is associated with HCV infection among rural people who inject drugs (PWID). Methods: Data are from a cross-sectional sample of adults who reported injecting drugs in the past 30 days recruited from rural counties in New Hampshire, Vermont, and Massachusetts (2018-2019). We calculated the road network distance between each participant's address and the nearest fixed-site SSP, categorized as ≤ 1 mile, 1-3 miles, 3-10 miles, and > 10 miles. Staff performed HCV antibody tests and a survey assessed past 30-day injection equipment sharing practices: borrowing used syringes, borrowing other used injection equipment, and backloading. Mixed effects modified Poisson regression estimated prevalence ratios (aPR) and 95% confidence intervals (95% CI). Analyses were also stratified by means of transportation. Results: Among 330 PWID, 25% lived ≤ 1 mile of the nearest SSP, 17% lived 1-3 miles of an SSP, 12% lived 3-10 miles of an SSP, and 46% lived > 10 miles from an SSP. In multivariable models, compared to PWID who lived within 1 mile of an SSP, those who lived 3 to 10 miles away had a higher prevalence of HCV seropositivity (aPR: 1.25, 95% CI 1.06-1.46), borrowing other used injection equipment (aPR: 1.23, 95% CI 1.04-1.46), and backloading (aPR: 1.48, 95% CI 1.17-1.88). Similar results were observed for PWID living > 10 miles from an SSP: aPR [HCV]: 1.19, 95% CI 1.01-1.40; aPR [borrowing other used equipment]:1.45, 95% CI 1.29-1.63; and aPR [backloading]: 1.59, 95% CI 1.13-2.24. Associations between living 1 to 3 miles of an SSP and each outcome did not reach statistical significance. When stratified by means of transportation, associations between distance to SSP and each outcome (except borrowing other used injection equipment) were only observed among PWID who traveled by other means (versus traveled by automobile). Conclusions: Among PWID in rural New England, living farther from a fixed-site SSP was associated with a higher prevalence of HCV seropositivity, borrowing other used injection equipment, and backloading, reinforcing the need to increase SSP accessibility in rural areas. Means of transportation may modify this relationship.
    • Investigating the etiologies of non-malarial febrile illness in Senegal using metagenomic sequencing

      Levine, Zoë C; Sene, Aita; Mkandawire, Winnie; Deme, Awa B; Ndiaye, Tolla; Sy, Mouhamad; Gaye, Amy; Diedhiou, Younouss; Mbaye, Amadou M; Ndiaye, Ibrahima M; et al. (2024-01-25)
      The worldwide decline in malaria incidence is revealing the extensive burden of non-malarial febrile illness (NMFI), which remains poorly understood and difficult to diagnose. To characterize NMFI in Senegal, we collected venous blood and clinical metadata in a cross-sectional study of febrile patients and healthy controls in a low malaria burden area. Using 16S and untargeted sequencing, we detected viral, bacterial, or eukaryotic pathogens in 23% (38/163) of NMFI cases. Bacteria were the most common, with relapsing fever Borrelia and spotted fever Rickettsia found in 15.5% and 3.8% of cases, respectively. Four viral pathogens were found in a total of 7 febrile cases (3.5%). Sequencing also detected undiagnosed Plasmodium, including one putative P. ovale infection. We developed a logistic regression model that can distinguish Borrelia from NMFIs with similar presentation based on symptoms and vital signs (F1 score: 0.823). These results highlight the challenge and importance of improved diagnostics, especially for Borrelia, to support diagnosis and surveillance.
    • Practice Site Heterogeneity within and between Medicaid Accountable Care Organizations

      Dyer, Zachary; Alcusky, Matthew J; Himmelstein, Jay; Ash, Arlene S.; Kerrissey, Michaela (2024-01-20)
      The existing literature has considered accountable care organizations (ACOs) as whole entities, neglecting potentially important variations in the characteristics and experiences of the individual practice sites that comprise them. In this observational cross-sectional study, our aim is to characterize the experience, capacity, and process heterogeneity at the practice site level within and between Medicaid ACOs, drawing on the Massachusetts Medicaid and Children's Health Insurance Program (MassHealth), which launched an ACO reform effort in 2018. We used a 2019 survey of a representative sample of administrators from practice sites participating in Medicaid ACOs in Massachusetts (n = 225). We quantified the clustering of responses by practice site within all 17 Medicaid ACOs in Massachusetts for measures of process change, previous experience with alternative payment models, and changes in the practices' ability to deliver high-quality care. Using multilevel logistic models, we calculated median odds ratios (MORs) and intraclass correlation coefficients (ICCs) to quantify the variation within and between ACOs for each measure. We found greater heterogeneity within the ACOs than between them for all measures, regardless of practice site and ACO characteristics (all ICCs ≤ 0.26). Our research indicates diverse experience with, and capacity for, implementing ACO initiatives across practice sites in Medicaid ACOs. Future research and program design should account for characteristics of practice sites within ACOs.
    • mRNA initiation and termination are spatially coordinated [preprint]

      Calvo-Roitberg, Ezequiel; Carroll, Christine L; Venev, Sergey V; Kim, GyeungYun; Mick, Steven T; Dekker, Job; Fiszbein, Ana; Pai, Athma A (2024-01-07)
      The expression of a precise mRNA transcriptome is crucial for establishing cell identity and function, with dozens of alternative isoforms produced for a single gene sequence. The regulation of mRNA isoform usage occurs by the coordination of co-transcriptional mRNA processing mechanisms across a gene. Decisions involved in mRNA initiation and termination underlie the largest extent of mRNA isoform diversity, but little is known about any relationships between decisions at both ends of mRNA molecules. Here, we systematically profile the joint usage of mRNA transcription start sites (TSSs) and polyadenylation sites (PASs) across tissues and species. Using both short and long read RNA-seq data, we observe that mRNAs preferentially using upstream TSSs also tend to use upstream PASs, and congruently, the usage of downstream sites is similarly paired. This observation suggests that mRNA 5' end choice may directly influence mRNA 3' ends. Our results suggest a novel "Positional Initiation-Termination Axis" (PITA), in which the usage of alternative terminal sites are coupled based on the order in which they appear in the genome. PITA isoforms are more likely to encode alternative protein domains and use conserved sites. PITA is strongly associated with the length of genomic features, such that PITA is enriched in longer genes with more area devoted to regions that regulate alternative 5' or 3' ends. Strikingly, we found that PITA genes are more likely than non-PITA genes to have multiple, overlapping chromatin structural domains related to pairing of ordinally coupled start and end sites. In turn, PITA coupling is also associated with fast RNA Polymerase II (RNAPII) trafficking across these long gene regions. Our findings indicate that a combination of spatial and kinetic mechanisms couple transcription initiation and mRNA 3' end decisions based on ordinal position to define the expression mRNA isoforms.
    • Spatial characterization of interface dermatitis in cutaneous lupus reveals novel chemokine ligand-receptor pairs that drive disease [preprint]

      Shakiba, Saeed; Haddadi, Nazgol-Sadat; Afshari, Khashayar; Lubov, Janet E; Raef, Haya S; Li, Robert; Yildiz-Altay, Ümmügülsüm; Daga, Mridushi; Refat, Maggi Ahmed; Kim, Evangeline; et al. (2024-01-06)
      Chemokines play critical roles in the recruitment and activation of immune cells in both homeostatic and pathologic conditions. Here, we examined chemokine ligand-receptor pairs to better understand the immunopathogenesis of cutaneous lupus erythematosus (CLE), a complex autoimmune connective tissue disorder. We used suction blister biopsies to measure cellular infiltrates with spectral flow cytometry in the interface dermatitis reaction, as well as 184 protein analytes in interstitial skin fluid using Olink targeted proteomics. Flow and Olink data concordantly demonstrated significant increases in T cells and antigen presenting cells (APCs). We also performed spatial transcriptomics and spatial proteomics of punch biopsies using digital spatial profiling (DSP) technology on CLE skin and healthy margin controls to examine discreet locations within the tissue. Spatial and Olink data confirmed elevation of interferon (IFN) and IFN-inducible CXCR3 chemokine ligands. Comparing involved versus uninvolved keratinocytes in CLE samples revealed upregulation of essential inflammatory response genes in areas near interface dermatitis, including AIM2. Our Olink data confirmed upregulation of Caspase 8, IL-18 which is the final product of AIM2 activation, and induced chemokines including CCL8 and CXCL6 in CLE lesional samples. Chemotaxis assays using PBMCs from healthy and CLE donors revealed that T cells are equally poised to respond to CXCR3 ligands, whereas CD14+CD16+ APC populations are more sensitive to CXCL6 via CXCR1 and CD14+ are more sensitive to CCL8 via CCR2. Taken together, our data map a pathway from keratinocyte injury to lymphocyte recruitment in CLE via AIM2-Casp8-IL-18-CXCL6/CXCR1 and CCL8/CCR2, and IFNG/IFNL1-CXCL9/CXCL11-CXCR3.
    • Derivation and Internal Validation of a Mortality Prognostication Machine Learning Model in Ebola Virus Disease Based on Iterative Point-of-Care Biomarkers

      Bearnot, Courtney J; Mbong, Eta N; Muhayangabo, Rigo F; Laghari, Razia; Butler, Kelsey M.; Gainey, Monique; Perera, Shiromi M; Michelow, Ian C; Tang, Oliver Y; Levine, Adam C; et al. (2024-01-05)
      Background: Although multiple prognostic models exist for Ebola virus disease mortality, few incorporate biomarkers, and none has used longitudinal point-of-care serum testing throughout Ebola treatment center care. Methods: This retrospective study evaluated adult patients with Ebola virus disease during the 10th outbreak in the Democratic Republic of Congo. Ebola virus cycle threshold (Ct; based on reverse transcriptase polymerase chain reaction) and point-of-care serum biomarker values were collected throughout Ebola treatment center care. Four iterative machine learning models were created for prognosis of mortality. The base model used age and admission Ct as predictors. Ct and biomarkers from treatment days 1 and 2, days 3 and 4, and days 5 and 6 associated with mortality were iteratively added to the model to yield mortality risk estimates. Receiver operating characteristic curves for each iteration provided period-specific areas under curve with 95% CIs. Results: Of 310 cases positive for Ebola virus disease, mortality occurred in 46.5%. Biomarkers predictive of mortality were elevated creatinine kinase, aspartate aminotransferase, blood urea nitrogen (BUN), alanine aminotransferase, and potassium; low albumin during days 1 and 2; elevated C-reactive protein, BUN, and potassium during days 3 and 4; and elevated C-reactive protein and BUN during days 5 and 6. The area under curve substantially improved with each iteration: base model, 0.74 (95% CI, .69-.80); days 1 and 2, 0.84 (95% CI, .73-.94); days 3 and 4, 0.94 (95% CI, .88-1.0); and days 5 and 6, 0.96 (95% CI, .90-1.0). Conclusions: This is the first study to utilize iterative point-of-care biomarkers to derive dynamic prognostic mortality models. This novel approach demonstrates that utilizing biomarkers drastically improved prognostication up to 6 days into patient care.
    • Change in Sexual and Reproductive Health Knowledge among Young Women Using the Conversational Agent "Nthabi" in Lesotho: A Clinical Trial [preprint]

      Nkabane-Nkholongo, Elizabeth; Mokgatle, Mathildah; Bickmore, Timothy; Julce, Clevanne; Thompson, David; Jack, Brian (2023-12-28)
      Background: Young women worldwide face problems like unwanted pregnancy and sexually transmitted infections. Providing sexual and reproductive health education to this population remains a priority. It is unknown if using digital health interventions to deliver health education in human resource-constrained settings is effective. Methods: We conducted a clinical trial of the Nthabi intervention to determine participant's knowledge before and after discussion of family planning, folic acid and healthy eating among young women aged 18-28 years in two rural districts of Lesotho who used the Nthabi conversational agent system on either smartphones or tablets for up to six weeks. The number of correct pre- and post-test responses were compared using generalized linear models that directly estimated the proportions and percentages of correct responses. Results: Of the 172 participants enrolled, the mean age was 22.5 years, 91% were unmarried, 69% completed high school, 23% were unemployed and 66% were students. The mean number of interactions with Nthabi was Family planning was chosen to be discussed by 82 (52.2%), of the 172 participants and of those, 49 (59.8%) completed the content on this topic, and 26 (53.1%) completed the post-test. For the 11 questions about family planning, there were 717 (76.6%) correct responses on the pre-test and 320 (89.9%) on the post-test (p = 0.0233). Folic acid was chosen to be discussed by 74 (47.1%) of 172 participants, and of those, 27 (36.5%) completed the content on this topic, and all 27 (100%) completed the post-test. For the 5 questions about folic acid use, there were 181 (45.3%) correct responses on the pre-test and 111 (71.6%) on the post-test (p < 0.0001). The number of correct responses on the post-test was positively associated with the number of sessions that the participant engaged with Nthabi. Conclusion: The Nthabi conversational agent system increased knowledge of family planning methods and folic acid use among young women in Lesotho. Digital health interventions like Nthabi offer new opportunities to deliver reproductive health information in countries that have limited human resources for health. Trial registration: ClinicalTrials.gov ID: NCT04354168.
    • Stem cells and pain

      da Silva, Matheus Deroco Veloso; Piva, Maiara; Martelossi-Cebinelli, Geovana; Stinglin Rosa Ribas, Mariana; Hoffmann Salles Bianchini, Beatriz; Heintz, Olivia K; Casagrande, Rubia; Verri, Waldiceu A (2023-12-26)
      Pain can be defined as an unpleasant sensory and emotional experience caused by either actual or potential tissue damage or even resemble that unpleasant experience. For years, science has sought to find treatment alternatives, with minimal side effects, to relieve pain. However, the currently available pharmacological options on the market show significant adverse events. Therefore, the search for a safer and highly efficient analgesic treatment has become a priority. Stem cells (SCs) are non-specialized cells with a high capacity for replication, self-renewal, and a wide range of differentiation possibilities. In this review, we provide evidence that the immune and neuromodulatory properties of SCs can be a valuable tool in the search for ideal treatment strategies for different types of pain. With the advantage of multiple administration routes and dosages, therapies based on SCs for pain relief have demonstrated meaningful results with few downsides. Nonetheless, there are still more questions than answers when it comes to the mechanisms and pathways of pain targeted by SCs. Thus, this is an evolving field that merits further investigation towards the development of SC-based analgesic therapies, and this review will approach all of these aspects.
    • Intraflagellar transport: A critical player in photoreceptor development and the pathogenesis of retinal degenerative diseases

      Gupta, Mohona; Pazour, Gregory J (2023-12-23)
      In vertebrate vision, photons are detected by highly specialized sensory cilia called outer segments. Photoreceptor outer segments form by remodeling the membrane of a primary cilium into a stack of flattened disks. Intraflagellar transport (IFT) is critical to the formation of most types of eukaryotic cilia including the outer segments. This review covers the state of knowledge of the role of IFT in the formation and maintenance of outer segments and the human diseases that result from mutations in genes encoding the IFT complex and associated motors.
    • ATXN2 is a target of N-terminal proteolysis

      Chitre, Monika; Emery, Patrick (2023-12-21)
      Spinocerebellar ataxia 2 (SCA2) is a neurodegenerative disorder caused by the expansion of the poly-glutamine (polyQ) tract of Ataxin-2 (ATXN2). Other polyQ-containing proteins such as ATXN7 and huntingtin are associated with the development of neurodegenerative diseases when their N-terminal polyQ domains are expanded. Furthermore, they undergo proteolytic processing events that produce N-terminal fragments that include the polyQ stretch, which are implicated in pathogenesis. Interestingly, N-terminal ATXN2 fragments were reported in a brain extract from a SCA2 patient, but it is currently unknown whether an expanded polyQ domain contributes to ATXN2 proteolytic susceptibility. Here, we used transient expression in HEK293 cells to determine whether ATXN2 is a target for specific N-terminal proteolysis. We found that ATXN2 proteins with either normal or expanded polyQ stretches undergo proteolytic cleavage releasing an N-terminal polyQ-containing fragment. We identified a short amino acid sequence downstream of the polyQ domain that is necessary for N-terminal cleavage of full-length ATXN2 and sufficient to induce proteolysis of a heterologous protein. However, this sequence is not required for cleavage of a short ATXN2 isoform produced from an alternative start codon located just upstream of the CAG repeats encoding the polyQ domain. Our study extends our understanding of ATXN2 posttranslational regulation by revealing that this protein can be the target of specific proteolytic cleavage events releasing polyQ-containing products that are modulated by the N-terminal domain of ATXN2. N-terminal ATXN2 proteolysis of expanded polyQ domains might contribute to SCA2 pathology, as observed in other neurodegenerative disorders caused by polyQ domain expansion.
    • Genetic ablation of Sarm1 attenuates expression and mislocalization of phosphorylated TDP-43 after mouse repetitive traumatic brain injury

      Dogan, Elif O; Bouley, James; Zhong, Jianjun; Harkins, Ashley L; Keeler, Allison M; Bosco, Daryl A; Brown, Robert H; Henninger, Nils (2023-12-20)
      Traumatic brain injury (TBI), particularly when moderate-to-severe and repetitive, is a strong environmental risk factor for several progressive neurodegenerative disorders. Mislocalization and deposition of transactive response DNA binding protein 43 (TDP-43) has been reported in both TBI and TBI-associated neurodegenerative diseases. It has been hypothesized that axonal pathology, an early event after TBI, may promote TDP-43 dysregulation and serve as a trigger for neurodegenerative processes. We sought to determine whether blocking the prodegenerative Sarm1 (sterile alpha and TIR motif containing 1) axon death pathway attenuates TDP-43 pathology after TBI. We subjected 111 male Sarm1 wild type, hemizygous, and knockout mice to moderate-to-severe repetitive TBI (rTBI) using a previously established injury paradigm. We conducted serial neurological assessments followed by histological analyses (NeuN, MBP, Iba-1, GFAP, pTDP-43, and AT8) at 1 month after rTBI. Genetic ablation of the Sarm1 gene attenuated the expression and mislocalization of phosphorylated TDP-43 (pTDP-43) and accumulation of pTau. In addition, Sarm1 knockout mice had significantly improved cortical neuronal and axonal integrity, functional deficits, and improved overall survival after rTBI. In contrast, removal of one Sarm1 allele delayed, but did not prevent, neurological deficits and neuroaxonal loss. Nevertheless, Sarm1 haploinsufficient mice showed significantly less microgliosis, pTDP-43 pathology, and pTau accumulation when compared to wild type mice. These data indicate that the Sarm1-mediated prodegenerative pathway contributes to pathogenesis in rTBI including the pathological accumulation of pTDP-43. This suggests that anti-Sarm1 therapeutics are a viable approach for preserving neurological function after moderate-to-severe rTBI.