Faculty Bibliography

Animals need daily intakes of three macronutrients: sugar, protein, and fat. Under fasted conditions, however, animals prioritize sugar as a primary source of energy. They must detect ingested sugar-specifically D-glucose-and quickly report its presence to the brain. Hypothalamic neurons that can respond to the caloric content in the gut regardless of the identity of macronutrient have been identified, but until now, the existence of neurons that can encode the specific macronutrients remained unknown. We found that a subset of corticotropin-releasing factor (CRF)-expressing neurons in the hypothalamic paraventricular nucleus (CRF^PVN) respond specifically to D-glucose in the gut, separately from other macronutrients or sugars. CRF^PVN neuronal activity is essential for fasted mice to develop a preference for D-glucose. These responses of CRF^PVN neurons to intestinal D-glucose require a specific spinal gut-brain pathway including the dorsal lateral parabrachial nuclei. These findings reveal the neural circuit that encodes the identity of D-glucose.

OBJECTIVE:This study examined racial and ethnic differences in percent total weight loss (%TWL) and glycemic improvement following sleeve gastrectomy (SG) and explored the role of socioeconomic and psychosocial factors in postsurgical outcomes. METHODS:This longitudinal study included patients who underwent SG between 2017 and 2020, with follow-up visits over 24 months. RESULTS:Non-Hispanic Black (NHB) participants had lower %TWL at 3, 12, and 24 months compared with Hispanic (H) and non-Hispanic White (NHW) participants. Fat mass index was initially lower in NHB, with smaller reductions over time and significant group differences persisting at 24 months. NHB participants had higher baseline fat-free mass index values; by 24 months, fat-free mass index values were lower in H participants. Hemoglobin A1c decreased across all groups but remained consistently higher in NHB and H compared with NHW at 24 months. NHB participants reported higher perceived discrimination, sleep disturbance, and perceived stress than H and NHW participants at all time points. Employment status predicted %TWL at 12 months. There was a significant interaction between race and ethnicity and employment status observed at 12 and 24 months, suggesting that employment-related disparities could impact surgical outcomes. CONCLUSIONS:NHB participants experienced less favorable outcomes following SG, emphasizing the need for tailored interventions addressing socioeconomic and psychosocial disparities.

Allergic contact dermatitis (ACD) is a delayed-type IV hypersensitivity response driven by innate and adaptive immune cells. While specific immune regulations of these cell types are amply elucidated, their regulations by extracellular matrix (ECM) components and T cell mediated adaptive immunity in ACD remains unclear. Lumican and biglycan are ECM proteoglycans abundant in the dermis and lymph node, known to regulate innate immune myeloid cells, but have not been investigated in lymphoid cell regulations in ACD. By immunohistology we localized lumican and biglycan in skin biopsies of psoriatic patients. Using wild type (WT), lumican and biglycan knockout mice, we investigated CD4⁺T cell infiltration, activation and proliferation in the skin and draining lymph node (dLN) of CHS-challenged mice by immunohistochemistry and flow cytometry. We used the OT-II adoptive transfer model to test antigen specific CD4⁺T cell activation. We assessed interactions of the proteoglycans with LFA-1 on T cells by confocal microscopy. Compared to WTs, the knockouts showed severe ear inflammation, with increased CD4⁺T cells infiltration in the dermis. CHS-challenged knockout mice dLN showed increased T-bet, STAT1 and -STAT4 signaling, indicating enhanced Th1 commitment and proliferation. We found that WT lymph node fibroblastic reticular cells (FRCs) secrete lumican, biglycan and decorin, a related proteoglycan, while none are expressed by naive or activated T cells. Lumican and biglycan interact with LFA-1 on T cell surfaces, and in vitro all three proteoglycans suppress CD4⁺T cell activation. Secreted by dLN FRCs, lumican, biglycan, and possibly decorin interact with LFA-1 on CD4⁺T cells to restrict its activation and reduce dermatitis severity.

AIM/OBJECTIVE:To investigate how psychosocial stress contributes to accelerated thrombosis, focusing on platelet activation and hyperreactivity. The specific objective was to identify novel platelet regulators involved in stress-mediated thrombosis, with a particular emphasis on the tetraspanin CD37. METHODS AND RESULTS/RESULTS:To explore how stress contributes to platelet hyperreactivity, platelets were isolated from (1) mice that experienced chronic variable stress and stress-free controls (n=8/group) and (2) human subjects with self-reported high and no stress levels (n=18/group), followed by RNA-sequencing. By comparing mutually expressed transcripts, a subset of genes differentially expressed following psychosocial stress was identified in both human and mouse platelets. In both mice and humans, platelet CD37 positively associates with platelet aggregation responses that underlie thrombosis, with Cd37-/- platelets exhibiting impaired integrin αIIbβ3 signaling, characterized by reduced platelet fibrinogen spreading and decreased agonist-induced αIIbβ3 activation. Consistent with a role for CD37 in regulating platelet activation responses, chimeric mice that received Cd37-/- bone marrow experienced a significantly increased time to vessel occlusion in the carotid artery FeCl3 model compared to mice reconstituted with wild-type bone marrow. CD37 deficiency did not alter hemostasis, as platelet count, coagulation metrics, prothrombin time, and partial thromboplastin time did not differ in Cd37-/- mice relative to wild-type mice. Consistent with this, bleeding time did not differ between wild-type and Cd37-/- mice following tail tip transection. CONCLUSIONS:This study provides new insights into the platelet-associated mechanisms underlying stress-mediated thrombosis. Identifying CD37 as a novel regulator of platelet activation responses offers potential therapeutic targets for reducing the thrombotic risk associated with psychosocial stress. The findings also contribute to understanding how psychosocial stress accelerates thrombotic events and underscore the importance of platelet activation in this process.

Targeted therapies and immunotherapy have improved treatment outcomes for many melanoma patients. However, patients whose melanomas harbor driver mutations in the neurofibromin 1 (NF1) tumor suppressor gene often lack effective targeted treatment options when their tumors do not respond to immunotherapy. In this study, we utilized patient-derived short-term cultures (STCs) and multiomics approaches to identify molecular features that could inform the development of therapies for patients with NF1 mutant melanoma. Differential gene expression analysis revealed that the epidermal growth factor receptor (EGFR) is highly expressed and active in NF1 mutant melanoma cells, where it hyper-activates ERK and AKT, leading to increased tumor cell proliferation, survival, and growth. In contrast, genetic or pharmacological inhibition of EGFR hindered cell proliferation and survival and suppressed tumor growth in patient-derived NF1 mutant melanoma models but not in NF1 wild-type models. These results reveal a connection between NF1 loss and increased EGFR expression that is critical for the survival and growth of NF1 mutant melanoma cells in patient-derived culture and xenograft models, irrespective of their BRAF and NRAS mutation status.

The intestinal secretory lineage is thought to comprise four distinct cell types derived from one Atoh1⁺ progenitor, but the mechanisms that distinguish Paneth and goblet cells are unclear. Bhattacharya et al.¹ argue that these cells are instead phenotypic manifestations of a common terminal Atoh1⁺ cell, actively shaped by niche-derived signals.

BACKGROUND:/calmodulin-dependent protein kinase II and selected for probe collection. RESULTS:This approach significantly reduced the amount of FFPE tissue needed for robust single population RNA-seq. We demonstrate ~20 identified L3 or L5 pyramidal neurons or one lamina-specific cortical ribbon from a single 5µm thick section is sufficient to generate robust RNA-seq reads. Bioinformatic analysis of neurons and ribbons showed notable similarities and differences reflective of the single neuron and multiple admixed cell types within the former and latter, respectively. Comparison with existing methods Protocols exist for DSP of postmortem human FFPE brain tissue. However, this new approach enables profiling small groups of ~14-21 pyramidal neurons using the GeoMx DSP platform. CONCLUSIONS:This optimized DSP assay provides high resolution RNA-seq data demonstrating utility and versatility of the GeoMx platform for individually characterized neurons and isolated cortical ribbons within postmortem FFPE human brain tissue for downstream analyses.

Alzheimer's disease (AD) is characterized by the deposition of full-length and truncated amyloid beta (Aβ) species within brain parenchyma and cerebral vessels. However, Aβ truncated species remain understudied. Here, we present a protocol for culture and characterization of a mouse monoclonal antibody targeting N-terminally truncated proteoforms starting at position 4. We describe a detailed procedure for hybridoma culture, antibody collection, and isolation via affinity chromatography. We then describe steps for target validation via dot blot, as well as potential applications. For complete details on the use and execution of this protocol, please refer to Cabrera et al. and Rostagno et al.¹

BACKGROUND:Synovial fluid (SF) biomarkers demonstrate time-dependent variation after acute knee injury, and it is postulated that persistently elevated inflammatory markers may mediate worse long-term outcomes. PURPOSE/OBJECTIVE:This study investigated the relationship between biomarkers in SF at the time of meniscectomy and long-term patient-reported outcomes in patients with acute versus chronic meniscal injuries. STUDY DESIGN/METHODS:Cohort study; Level of evidence, 3. METHODS:This retrospective analysis included patients who underwent knee SF aspiration on the day of arthroscopic meniscectomy between October 2011 and October 2020 with minimum 4-year follow-up. SF aspirated from the operative knee was analyzed for 10 pro- and anti-inflammatory biomarkers. Patients completed the visual analog scale for pain, Lysholm Knee Questionnaire, Tegner Activity Scale, and Knee injury and Osteoarthritis Outcome Score-Physical Function Short-form (KOOS-PS) before surgery and at follow-up. Patients were categorized as having acute (<6 weeks) or chronic (>1 year) symptoms. K-means clustering analysis was performed using biomarker levels to group patients into distinct cohorts. RESULTS:= .020) than the low-inflammation cohort. CONCLUSION/CONCLUSIONS:In patients with chronic meniscal injury, those with a more proinflammatory SF biomarker profile at the time of meniscectomy had worse outcomes than those who had a low inflammatory profile. In acute meniscal injuries, most patients demonstrate a high inflammatory profile, which was not associated with a difference in long-term outcomes.