The integrated stress response promotes macrophage inflammation and migration in autoimmune diabetes

Cell Communication and Signaling · 2025-08-20 · 2 citations

Type 1 diabetes (T1D) is an autoimmune disease characterized by the destruction of insulin-producing pancreatic β-cells. Macrophages infiltrate islets early in T1D pathogenesis, preceding the influx of T- and B-lymphocytes. The integrated stress response (ISR), a cellular pathway activated during stress, coordinates adaptive changes in gene expression to maintain cell function and survival. To study the ISR in macrophages, bone-marrow-derived macrophages were treated with a pharmacological inhibitor of the ISR (ISRIB) and polarized to a proinflammatory M1-like state. We observed a reduction in the number of proinflammatory macrophages, as well as a decrease in iNOS mRNA and protein levels, following ISRIB treatment. RNA-sequencing revealed a reduction in pathways related to stress responses, including ER stress, reactive oxygen species (ROS) regulation, and autophagy, as well as migration pathway genes. ISRIB treatment led to decreased macrophage migration after stimulation in vitro and reduced migration of macrophages to the site of injury after tailfin injury in zebrafish in vivo. Interestingly, ISRIB mediated reduction of M1-like macrophages and reduction of migration was recapitulated by the inhibition of PKR but not PERK, both upstream ISR kinases, highlighting PKR as a key mediator of the ISR in macrophages. Pre-diabetic female non-obese diabetic (NOD) mice administered ISRIB demonstrated an overall reduction in the macrophage numbers in the pancreatic islets. Additionally, the insulitic area of pancreata from ISRIB treated NOD mice had increased PD-L1 levels. PD-L1 protein but not mRNA levels were increased in M1-like macrophages after ISR and PKR inhibition. Our findings identify the ISR, particularly via PKR, as a critical regulator of macrophage driven inflammation and migration in T1D. Our study offers new insights into ISR signaling in macrophages, demonstrating that the ISR may serve as a potential target for intervention in macrophages during early T1D pathogenesis.

Hypusinated and unhypusinated isoforms of the translation factor eIF5A exert distinct effects in models of pancreas development and function

Journal of Biological Chemistry · 2025-01-18 · 5 citations

Hypusination of eukaryotic translation initiation factor 5A (eIF5A) is essential for its role in translation elongation and termination. Although the function of hypusinated eIF5A (eIF5A^Hyp) in cellular proliferation is well characterized, the role of its unhypusinated form (eIF5A^Lys) remains unclear. We hypothesized that eIF5A^Lys exerts independent and negative effects on cellular replication and metabolism, distinct from the loss of eIF5A^Hyp. To test this hypothesis, we utilized zebrafish and mouse models with inducible knockdowns of deoxyhypusine synthase (DHPS) and eIF5A to investigate their roles in cellular growth. Gene expression analysis <i>via</i> RNA sequencing and morphometric measurements of pancreas and β-cell mass were performed to assess phenotypic changes and identify affected biological pathways. Loss of DHPS in zebrafish resulted in significant defects in pancreatic growth, accompanied by changes in gene expression related to mRNA translation, neurogenesis, and stress pathways. By contrast, knockdown of eIF5A had minimal impact on pancreas development, suggesting that the effects of DHPS loss are not solely because of the lack of eIF5A^Hyp. In mice, β-cell–specific deletion of DHPS impaired β-cell mass expansion and glucose tolerance, whereas eIF5A deletion had no statistically significant effects. These findings provide evidence for an independent role for eIF5A^Lys in regulating developmental and functional responses in pancreas health and disease.

Advancements in GaN DFBs with embedded gratings and a path to higher power

2025-03-21

GaN-based distributed feedback (DFB) laser diodes are narrow linewidth sources promising for integration into low-size, weight, and power photonic circuits. There is a need to improve the linewidth, expand the availability of technologically useful wavelengths, and increase the power and efficiency for several applications. BluGlass presents advancements in visible wavelength DFB lasers. We will show measured device results achieving higher side-mode-suppression ratio of 40dB and a peak full-width half maximum under 3pm demonstrating near single frequency emission. Devices targeting critical atomic transition wavelengths for clocks, quantum computing, and other cold physics applications are covered spanning from 408nm to 470nm. A path toward narrow-band high-power DFB sources will be presented with preliminary data on gain in GaN-based semiconductor optical amplifiers.

The function of Cxcl12b in habenular axon projection in zebrafish

Proceedings of the West Virginia Academy of Science · 2025-04-04

The habenula is a structure found in the midbrain that is associated with regulating emotion and behavior. Research shows that chemokine signaling is involved in proper axon growth and direction as the habenula connects to its midbrain target, the interpeduncular nucleus (IPN). Transcripts of the chemokine receptor, cxcr4b, are found in precursors of the habenula, and Cxcr4b is present in newly formed habenular axons. The chemokine ligand Cxcl12b is expressed posterior to habenular axons as they extend toward the IPN. Previous work has shown that overexpression of cxcl12b coincides with abnormal axon development. The purpose of this research is to understand what affect loss of Cxcl12b has on proper axon projection from the habenula. We have produced fish with both a fluorescent marker of the habenula and a mutation in cxcl12b. After imaging their habenulae, we collect their DNA and genotype the larvae. The habenular axons of homozygous mutants will be compared to those of their heterozygous and wild type siblings. We hypothesize that cxcl12b mutation will result in improper habenular axon projection toward the IPN.

12-Lipoxygenase Inhibition Improves Glycemia and Obesity-associated Inflammation in Male Human Gene Replacement Mice

Endocrinology · 2025-04-05 · 3 citations

Obesity-associated inflammation is characterized by macrophage infiltration into peripheral tissues, contributing to the progression of prediabetes and type 2 diabetes. 12-lipoxygenase (12-LOX) catalyzes the formation of pro-inflammatory eicosanoids and promotes the migration of macrophages, yet its role in obesity-associated inflammation remains incompletely understood. Furthermore, differences between mouse and human orthologs of 12-LOX have limited efforts to study existing pharmacologic inhibitors of 12-LOX. In this study, we used a human gene replacement mouse model in which the gene encoding mouse 12-LOX (Alox15) is replaced by the human ALOX12 gene. As a model of obesity and dysglycemia, we administered male mice a high-fat diet. We subsequently investigated the effects of VLX-1005, a potent and selective small molecule inhibitor of human 12-LOX. Oral administration of VLX-1005 resulted in improved glucose homeostasis, decreased β-cell dedifferentiation, and reduced macrophage infiltration in islets and adipose tissue. Analysis of the stromal vascular fraction from adipose tissue showed a reduction in myeloid cells and cytokine expression with VLX-1005 treatment, indicating decreased adipose tissue inflammation. In a distinct mouse model in which Alox15 was selectively deleted in myeloid cells, we observed decreased β-cell dedifferentiation and reduced macrophage infiltration in both islets and adipose tissue, suggesting that the effects of VLX-1005 may relate to the inhibition of 12-LOX in macrophages. These findings highlight 12-LOX as a key factor in obesity-associated inflammation and suggest that 12-LOX inhibition could serve as a therapeutic strategy to improve glucose homeostasis and peripheral inflammation in the setting of obesity and type 2 diabetes.

12-Lipoxygenase inhibition improves glucose homeostasis and obesity-associated inflammation in human gene replacement mice

bioRxiv (Cold Spring Harbor Laboratory) · 2025-01-13

ABSTRACT Obesity-associated inflammation is characterized by macrophage infiltration into peripheral tissues, contributing to the progression of prediabetes and type 2 diabetes (T2D). The enzyme 12-lipoxygenase (12-LOX) catalyzes the formation of pro-inflammatory eicosanoids and is known to promote the migration of macrophages, yet its role in obesity-associated inflammation remains incompletely understood. Furthermore, differences between mouse and human orthologs of 12-LOX have limited efforts to study existing pharmacologic inhibitors of 12-LOX. In this study, we utilized a human gene replacement mouse model in which the gene encoding mouse 12-LOX ( Alox15 ) is replaced by the human ALOX12 gene. As a model of obesity and dysglycemia, we administered these mice a high-fat diet. We subsequently investigated the effects of VLX-1005, a potent and selective small molecule inhibitor of human 12-LOX. Oral administration of VLX-1005 resulted in improved glucose homeostasis, decreased β cell dedifferentiation, and reduced macrophage infiltration in islets and adipose tissue. Analysis of the stromal vascular fraction from adipose tissue showed a reduction in myeloid cells and cytokine expression with VLX-1005 treatment, indicating decreased adipose tissue inflammation. In a distinct mouse model in which Alox15 was selectively deleted in myeloid cells, we observed decreased β cell dedifferentiation and reduced macrophage infiltration in both islets and adipose tissue, suggesting that the effects of VLX-1005 may relate to the inhibition of 12-LOX in macrophages. These findings highlight 12-LOX as a key factor in obesity-associated inflammation and suggest that 12-LOX inhibition could serve as a therapeutic strategy to improve glucose homeostasis and peripheral inflammation in the setting of obesity and T2D.

Fabrication and linewidth characterization of III-nitride distributed feedback laser diodes with embedded surface gratings

2025-03-19

III-Nitride distributed feedback (DFB) laser diodes offer an elegant chip-scale solution for single-frequency blue and green photon sources, but are challenging to fabricate due to the narrow Fabry-Pérot mode spacing, delicate p-contact layer, and lattice mismatch in the nitride material system. Here, we present MOCVD-grown InGaN-based DFBs fabricated with first- and third-order SiOx surface gratings embedded in the ITO p-cladding layer. We compare two fabrication methods: first using electron beam lithography of hydrogen silsesquioxane (HSQ), then a more cost-effective and scalable fabrication using holographic lithography. Blue DFBs exhibit single longitudinal mode behavior with 5 pm (resolution-limited) full-width at half maximum and 25 dB side mode suppression. We characterize the free-running frequency noise power spectral density of a 443 nm InGaN DFB with a first-order grating using a correlated delayed self-heterodyne frequency discriminator, yielding a free-running intrinsic linewidth of 685 kHz and a β-separation line integrated linewidth of 3.47 MHz.

The G Protein-Coupled Receptor GPR31 Promotes Pro-inflammatory Responses in Pancreatic Islets and Macrophages

bioRxiv (Cold Spring Harbor Laboratory) · 2025-10-04

ABSTRACT In type 1 diabetes (T1D), the innate and adaptive immune systems attack and eventually destroy the insulin-secreting pancreatic β cells. During this process, β cells activate inflammatory signaling pathways that augment the dysfunction and destruction imposed by cellular autoimmunity. The 12-lipoxygenase (12-LOX) pathway produces the pro-inflammatory eicosanoid 12-HETE, which induces oxidative and endoplasmic reticulum stress and results in diminished insulin secretion and apoptosis. The G protein-coupled receptor GPR31 has been identified as a putative receptor for 12-HETE. In this study, we generated conventional GPR31 knockout (KO) mice on the C57BL/6J background. To interrogate the role of GPR31 in β cells, we treated islets from wildtype and Gpr31b KO mice with pro-inflammatory cytokines and subjected the islets to RNA sequencing. Differentially expressed pathways in Gpr31b KO islets included those pertaining to inflammation and oxidative stress, consistent with functional studies that demonstrated reduced cytokine-induced oxidative stress in Gpr31b KO islets compared to wildtype controls. Bone marrow-derived macrophages from Gpr31b KO mice showed reduced macrophage migration and decreased inflammatory IFN-α and IFN-γ signaling by RNA sequencing. To mimic islet and macrophage inflammation as seen in T1D, wildtype and Gpr31b KO mice were treated with the diabetogenic toxin streptozotocin. Compared to wildtype, Gpr31b KO mice had improved glucose tolerance and preserved β-cell mass. siRNA knockdown of Gpr31b in non-obese diabetic (NOD) mice reduced insulitis, macrophage infiltration, and oxidative stress. Collectively, these findings are consistent with previously published data using 12/15-LOX KO mice and suggest that GPR31 mediates the pro-inflammatory responses of 12-HETE in both β cells and macrophages.

MRI morphometry of the anterior and posterior cerebellar vermis and its relationship to sensorimotor and cognitive functions in children

Developmental Cognitive Neuroscience · 2024-04-25 · 4 citations

INTRODUCTION: The human cerebellum emerges as a posterior brain structure integrating neural networks for sensorimotor, cognitive, and emotional processing across the lifespan. Developmental studies of the cerebellar anatomy and function are scant. We examine age-dependent MRI morphometry of the anterior cerebellar vermis, lobules I-V and posterior neocortical lobules VI-VII and their relationship to sensorimotor and cognitive functions. METHODS: Typically developing children (TDC; n=38; age 9-15) and healthy adults (HAC; n=31; 18-40) participated in high-resolution MRI. Rigorous anatomically informed morphometry of the vermis lobules I-V and VI-VII and total brain volume (TBV) employed manual segmentation computer-assisted FreeSurfer Image Analysis Program [http://surfer.nmr.mgh.harvard.edu]. The neuropsychological scores (WASI-II) were normalized and related to volumes of anterior, posterior vermis, and TBV. RESULTS: TBVs were age independent. Volumes of I-V and VI-VII were significantly reduced in TDC. The ratio of VI-VII to I-V (∼60%) was stable across age-groups; I-V correlated with visual-spatial-motor skills; VI-VII with verbal, visual-abstract and FSIQ. CONCLUSIONS: In TDC neither anterior I-V nor posterior VI-VII vermis attained adult volumes. The "inverted U" developmental trajectory of gray matter peaking in adolescence does not explain this finding. The hypothesis of protracted development of oligodendrocyte/myelination is suggested as a contributor to TDC's lower cerebellar vermis volumes.

Hypusinated and unhypusinated isoforms of eIF5A exert distinct effects in models of pancreas development and function

bioRxiv (Cold Spring Harbor Laboratory) · 2024-10-27

Abstract Hypusination of eukaryotic translation initiation factor 5A (eIF5A) is essential for its role in translation elongation and termination. Although the function of hypusinated eIF5A (eIF5A Hyp ) in cellular proliferation is well-characterized, the role of its unhypusinated form (eIF5A Lys ) remains unclear. We hypothesized that eIF5A Lys exerts independent effects on cellular replication and metabolism distinct from the loss of eIF5A Hyp . To test this hypothesis, we utilized zebrafish and mouse models with inducible knockdowns of deoxyhypusine synthase (DHPS) and eIF5A to investigate their roles in cellular growth. Gene expression analysis via RNA sequencing and morphometric measurements of pancreas and β-cell mass were performed to assess phenotypic changes and identify affected biological pathways. Loss of DHPS in zebrafish resulted in significant defects in pancreatic growth, accompanied by the dysregulation of mRNA translation, neurogenesis, and stress pathways. By contrast, knockdown of eIF5A had minimal impact on pancreas development, suggesting that the effects of DHPS loss are not solely due to the lack of eIF5A Hyp . In mice, β cell-specific deletion of DHPS impaired β cell mass expansion and glucose tolerance, while eIF5A deletion had no statistically significant effects. These findings reveal an independent role for eIF5A Lys in regulating developmental and functional responses and that a balance in levels of the hypusinated and unhypusinated isoforms of eIF5A may be pivotal in cellular phenotypes in health and disease.