The impact of chronic pain on brain gene expression.

Background: Chronic pain affects one fifth of American adults, contributing significant public health burden. Chronic pain mechanisms can be further understood through investigating brain gene expression. Methods: We tested differentially expressed genes (DEGs) in chronic pain, migraine, lifetime fentanyl and oxymorphone use, and with chronic pain genetic risk in four brain regions (dACC, DLPFC, MeA, BLA) and imputed cell type expression data from 304 postmortem donors. We compared findings across traits and with independent transcriptomics resources, and performed gene-set enrichment. Results: We identified two chronic pain DEGs: B4GALT and VEGFB in bulk dACC. We found over 2000 (primarily BLA microglia) chronic pain cell type DEGs. Findings were enriched for mouse microglia pain genes, and for hypoxia and immune response. Cross-trait DEG overlap was minimal. Conclusions: Chronic pain-associated gene expression is heterogeneous across cell type, largely distinct from that in pain-related traits, and shows BLA microglia are a key cell type.

A brief note on substantial sub-daily arsenic variability in pumping drinking-water wells in New Hampshire.

Large variations in redox-related water parameters, like pH and dissolved oxygen (DO), have been documented in New Hampshire (United States) drinking-water wells over the course of a few hours under pumping conditions. These findings suggest that comparable sub-daily variability in dissolved concentrations of redox-reactive and toxic arsenic (As) also may occur, representing a potentially critical public-health data gap and a fundamental challenge for long-term As-trends monitoring. To test this hypothesis, discrete groundwater As samples were collected approximately hourly during one day in May and again in August 2019 from three New Hampshire drinking-water wells (2 public-supply, 1 private) under active pumping conditions. Collected samples were assessed by laboratory analysis (total As [AsTot], As(III), As(V)) and by field analysis (AsTot) using a novel integrated biosensor system. Laboratory analysis revealed sub-daily variability (range) in AsTot concentrations equivalent to 16 % - 36 % of that observed in the antecedent 3-year bimonthly trend monitoring. Thus, the results indicated that, along with previously demonstrated seasonality effects, the timing and duration of pumping are important considerations when assessing trends in drinking-water As exposures and concomitant risks. Results also illustrated the utility of the field sensor for monitoring and management of AsTot exposures in near-real-time.

Genetically Regulated Gene Expression in the Brain Associated With Chronic Pain: Relationships With Clinical Traits and Potential for Drug Repurposing.

BACKGROUND: Chronic pain is a common, poorly understood condition. Genetic studies including genome-wide association studies have identified many relevant variants, which have yet to be translated into full understanding of chronic pain. Transcriptome-wide association studies using transcriptomic imputation methods such as S-PrediXcan can help bridge this genotype-phenotype gap. METHODS: We carried out transcriptomic imputation using S-PrediXcan to identify genetically regulated gene expression associated with multisite chronic pain in 13 brain tissues and whole blood. Then, we imputed genetically regulated gene expression for over 31,000 Mount Sinai BioMe participants and performed a phenome-wide association study to investigate clinical relationships in chronic pain-associated gene expression changes. RESULTS: We identified 95 experiment-wide significant gene-tissue associations (p < 7.97 × 10-7), including 36 unique genes and an additional 134 gene-tissue associations reaching within-tissue significance, including 53 additional unique genes. Of the 89 unique genes in total, 59 were novel for multisite chronic pain and 18 are established drug targets. Chronic pain genetically regulated gene expression for 10 unique genes was significantly associated with cardiac dysrhythmia, metabolic syndrome, disc disorders/dorsopathies, joint/ligament sprain, anemias, and neurologic disorder phecodes. Phenome-wide association study analyses adjusting for mean pain score showed that associations were not driven by mean pain score. CONCLUSIONS: We carried out the largest transcriptomic imputation study of any chronic pain trait to date. Results highlight potential causal genes in chronic pain development and tissue and direction of effect. Several gene results were also drug targets. Phenome-wide association study results showed significant associations for phecodes including cardiac dysrhythmia and metabolic syndrome, thereby indicating potential shared mechanisms.

Polymerization of Physisorbed Molecular Monolayers via Overhanging Alkynyl Chains: Characterization of Polymerization Kinetics and Monolayer Durability.

Monolayers self-assembled by triphenyleneethynylene (TPE) compounds bearing two terminal alkynyl chains were polymerized by Glaser-Hay (G-H) alkyne coupling at the acetonitrile-HOPG interface. The alkynyl chains extend into the solution due to the monolayer's dense-packed morphology. Reacting substructures that have no morphology-determining roles is a potential strategy for preserving monolayer morphology throughout polymerization. Monolayer G-H reaction kinetics and polymerized monolayer durability were characterized by using mass spectrometry and fluorescence. Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) and time-of-flight (TOF) MS were used to identify TPE-oligomers in the monolayer and to track the monolayer populations of TPE-monomer, -dimer, and -trimer as a function of G-H reaction duration. Comparison of the observed kinetics to a Monte Carlo simulation provided evidence of step-growth polymerization. The durability of polymerized monolayers depended strongly on the length of the alkynyl chains linked by G-H reaction. Polymerized T6y monolayers (O(CH2)3C≡CH alkynyl chains) desorbed minimally during 16-h immersion in 90 °C o-dichlorobenzene (oDCB), whereas polymerized T8y (O(CH2)5C≡CH alkynyl chains) and polymerized T11y (O(CH2)8C≡CH alkynyl chains), desorbed 33 and 60%, respectively, of their TPE units after 4 h in 90 °C oDCB. All the polymerized monolayers are much more durable than unpolymerized monolayers, which desorb quantitatively from HOPG when rinsed with 25 µL of oDCB. Polymerized T6y monolayer is a highly durable anchor that may be adapted to build multilayer structures "permanently" attached to the HOPG surface. The alkynyl chain length dependence may be useful for tuning polymerized TPE monolayer durability for specific applications.

Comorbidity Profiles of Posttraumatic Stress Disorder Across the Medical Phenome.

Background: Prior epidemiological research has linked PTSD with specific physical health problems, but the comprehensive landscape of medical conditions associated with PTSD remains uncharacterized. Electronic health records (EHR) provide an opportunity to overcome prior clinical knowledge gaps and uncover associations with biological relevance that potentially vary by sex. Methods: PTSD was defined among biobank participants (total N=123,365) in a major healthcare system using two ICD code-based definitions: broad (1+ PTSD or acute stress codes versus 0; NCase=14,899) and narrow (2+ PTSD codes versus 0; NCase=3,026). Using a phenome-wide association (PheWAS) design, we tested associations between each PTSD definition and all prevalent disease umbrella categories, i.e., phecodes. We also conducted sex-stratified PheWAS analyses including a sex-by-diagnosis interaction term in each logistic regression. Results: A substantial number of phecodes were significantly associated with PTSDNarrow (61%) and PTSDBroad (83%). While top associations were shared between the two definitions, PTSDBroad captured 334 additional phecodes not significantly associated with PTSDNarrow and exhibited a wider range of significantly associated phecodes across various categories, including respiratory, genitourinary, and circulatory conditions. Sex differences were observed, in that PTSDBroad was more strongly associated with osteoporosis, respiratory failure, hemorrhage, and pulmonary heart disease among male patients, and with urinary tract infection, acute pharyngitis, respiratory infections, and overweight among female patients. Conclusions: This study provides valuable insights into a diverse range of comorbidities associated with PTSD, including both known and novel associations, while highlighting the influence of sex differences and the impact of defining PTSD using EHR.

Transcriptional signatures of heroin intake and relapse throughout the brain reward circuitry in male mice.

Opioid use disorder (OUD) looms as one of the most severe medical crises facing society. More effective therapeutics will require a deeper understanding of molecular changes supporting drug-taking and relapse. Here, we develop a brain reward circuit-wide atlas of opioid-induced transcriptional regulation by combining RNA sequencing (RNA-seq) and heroin self-administration in male mice modeling multiple OUD-relevant conditions: acute heroin exposure, chronic heroin intake, context-induced drug-seeking following abstinence, and relapse. Bioinformatics analysis of this rich dataset identified numerous patterns of transcriptional regulation, with both region-specific and pan-circuit biological domains affected by heroin. Integration of RNA-seq data with OUD-relevant behavioral outcomes uncovered region-specific molecular changes and biological processes that predispose to OUD vulnerability. Comparisons with human OUD RNA-seq and genome-wide association study data revealed convergent molecular abnormalities and gene candidates with high therapeutic potential. These studies outline molecular reprogramming underlying OUD and provide a foundational resource for future investigations into mechanisms and treatment strategies.

"When you hear the noise, you know it's love": Family Support in American Indian Communities.

Family relationships are an important source of emotional and instrumental support. In American Indian (AI) communities, families often provide support for women during childbirth and childrearing. The present study sought to gain insight into the influence of family during the pregnancy, childbirth, and childrearing experiences of AI women from a Gulf Coast tribe. A qualitative descriptive research design was used, and 31 interviews were conducted with women from the tribe. The average age of participants was 51.17, and the majority of women had 2 to 3 children. Data was analyzed using a content analysis approach. Themes that emerged include: Influence of Childhood on Participant's Families and Parenting Styles, Significance of Family Emotional Closeness, Significance of Family Physical Closeness, Importance of Taking Care of Family Members, Importance of Family in Childbirth, and Generational Shifts in Caregiving. Results of the study may influence health interventions for this community, and results should encourage health care providers to consider positive implications of including family and community supports in care.

Integrating genetics and transcriptomics to study major depressive disorder: a conceptual framework, bioinformatic approaches, and recent findings.

Major depressive disorder (MDD) is a complex and heterogeneous psychiatric syndrome with genetic and environmental influences. In addition to neuroanatomical and circuit-level disturbances, dysregulation of the brain transcriptome is a key phenotypic signature of MDD. Postmortem brain gene expression data are uniquely valuable resources for identifying this signature and key genomic drivers in human depression; however, the scarcity of brain tissue limits our capacity to observe the dynamic transcriptional landscape of MDD. It is therefore crucial to explore and integrate depression and stress transcriptomic data from numerous, complementary perspectives to construct a richer understanding of the pathophysiology of depression. In this review, we discuss multiple approaches for exploring the brain transcriptome reflecting dynamic stages of MDD: predisposition, onset, and illness. We next highlight bioinformatic approaches for hypothesis-free, genome-wide analyses of genomic and transcriptomic data and their integration. Last, we summarize the findings of recent genetic and transcriptomic studies within this conceptual framework.

Convergent abnormalities in striatal gene networks in human cocaine use disorder and mouse cocaine administration models.

Cocaine use disorder (CUD) is an intractable syndrome, and rising overdose death rates represent a substantial public health crisis that exacts tremendous personal and financial costs on patients and society. Sharp increases in cocaine use drive the urgent need for better mechanistic insight into this chronic relapsing brain disorder that currently lacks effective treatment options. To investigate the transcriptomic changes involved, we conducted RNA sequencing on two striatal brain regions that are heavily implicated in CUD, the nucleus accumbens and caudate nucleus, from men suffering from CUD and matched controls. Weighted gene coexpression analyses identified CUD-specific gene networks enriched in ionotropic receptors and linked to lowered neuroinflammation, contrasting the proinflammatory responses found in opioid use disorder. Integration of comprehensive transcriptomic datasets from mouse cocaine self-administration models revealed evolutionarily conserved gene networks in CUD that implicate especially D1 medium spiny neurons as drivers of cocaine-induced plasticity.

Transcriptional signatures of heroin intake and seeking throughout the brain reward circuit.

Opioid use disorder (OUD) looms as one of the most severe medical crises currently facing society. More effective therapeutics for OUD requires in-depth understanding of molecular changes supporting drug-taking and relapse. Recent efforts have helped advance these aims, but studies have been limited in number and scope. Here, we develop a brain reward circuit-wide atlas of opioid-induced transcriptional regulation by combining RNA sequencing (RNAseq) and heroin self-administration in male mice modeling multiple OUD-relevant conditions: acute heroin exposure, chronic heroin intake, context-induced drug-seeking following prolonged abstinence, and heroin-primed drug-seeking (i.e., "relapse"). Bioinformatics analysis of this rich dataset identified numerous patterns of molecular changes, transcriptional regulation, brain-region-specific involvement in various aspects of OUD, and both region-specific and pan-circuit biological domains affected by heroin. Integrating RNAseq data with behavioral outcomes using factor analysis to generate an "addiction index" uncovered novel roles for particular brain regions in promoting addiction-relevant behavior, and implicated multi-regional changes in affected genes and biological processes. Comparisons with RNAseq and genome-wide association studies from humans with OUD reveal convergent molecular regulation that are implicated in drug-taking and relapse, and point to novel gene candidates with high therapeutic potential for OUD. These results outline broad molecular reprogramming that may directly promote the development and maintenance of OUD, and provide a foundational resource to the field for future research into OUD mechanisms and treatment strategies.

Thermo-responsive and mucoadhesive gels for the treatment of cystinosis.

Mucoadhesive thermogels were developed by crosslinking poly(n-isopropylacrylamide) based polymers with chitosan and incorporating disulfide bridges, capable of releasing cysteamine upon interaction with mucin, for the treatment of cystinosis. Through crosslinking with chitosan and incorporating varying concentrations of the disulfide monomer into the polymer backbone, the extent of how mucoadhesive the developed thermogels were could be controlled. Through disulfide bridging with mucin, the thermogels released 6 to 10 µg of the conjugate model 2-mercaptopyridine over five days. Utilizing chitosan as the crosslinker, the developed thermogels were shown to degrade to a statistically higher extent following incubation with lysozyme, the highest concentration tear enzyme, by gravimetric and rheologic analysis. The developed thermogels were extensively tested in vivo utilizing a rat model in which materials were applied directly to the corneal surface and a rabbit model in which thermogels were applied to the inferior fornix. With the developed models, there was no adverse reactions or visual discomfort incurred following application of the thermogels. It has been demonstrated that the thermogels produced can be applied to the inferior fornix and release the stable conjugated payload over several days. The developed thermogel was designed to improve upon the current clinical treatment options for ocular cystinosis which are acidic topical formulations that require reapplication multiple times a day.

Common genetic variation impacts stress response in the brain.

To explain why individuals exposed to identical stressors experience divergent clinical outcomes, we determine how molecular encoding of stress modifies genetic risk for brain disorders. Analysis of post-mortem brain (n=304) revealed 8557 stress-interactive expression quantitative trait loci (eQTLs) that dysregulate expression of 915 eGenes in response to stress, and lie in stress-related transcription factor binding sites. Response to stress is robust across experimental paradigms: up to 50% of stress-interactive eGenes validate in glucocorticoid treated hiPSC-derived neurons (n=39 donors). Stress-interactive eGenes show brain region- and cell type-specificity, and, in post-mortem brain, implicate glial and endothelial mechanisms. Stress dysregulates long-term expression of disorder risk genes in a genotype-dependent manner; stress-interactive transcriptomic imputation uncovered 139 novel genes conferring brain disorder risk only in the context of traumatic stress. Molecular stress-encoding explains individualized responses to traumatic stress; incorporating trauma into genomic studies of brain disorders is likely to improve diagnosis, prognosis, and drug discovery.

"Sympathy" vs."Empathy": Comparing experiences of I2Audits and disability simulations.

People with disability often experience stigma and discrimination, and people with disability in rural areas may experience these at higher rates. Additionally, people with disability in rural areas may have fewer opportunities for physical and social participation due to barriers in the built environment. Activities such as disability simulations and inclusive, interdisciplinary community planning workshops (i.e., I2Audits) seek to draw awareness to and address these problematic experiences. The present study used thematic analysis from qualitative research to examine the advantages and disadvantages of using disability simulations and I2Audits in rural communities. Findings suggest that disability simulations increase stigmatization, lead to feelings of embarrassment and discomfort, and do not capture the experiences of people with disability. On the other hand, I2Audits lead to meaningful environmental changes, create feelings of empowerment, and center the lived experiences of people with disability within a bio-psycho-social model of disability. Results suggest that not only can I2Audits be a powerful tool to draw attention to physical barriers that people with disability face, but they also draw attention to the multi-level changes needed to increase opportunities for participation and address sources of stigma and discrimination in rural areas.

The intersection of disability status and rurality in American Indian/Alaskan Native communities.

There is a noteworthy gap in the literature regarding disability in rural American Indian/Alaskan Native (AI/AN) communities. This is significant, as many tribal lands are in rural areas and AI/AN individuals experience some of the highest prevalence rates of disability. To address this gap, we used descriptive statistics to examine the intersection of AI/AN and rurality in disability prevalence. Results indicate that rural counties have the highest prevalence of disability for both Whites and AI/ANs and that AI/ANs experience higher prevalence rates than Whites. However, further analysis indicates that county makeup (counties with high prevalence of AI/AN in the general population) moderated this relationship. Specifically, rural counties with populations of at least 5% AI/AN had lower prevalence of AI/AN disability compared to counties with populations with less than 5% AI/AN. Further analysis is needed to unpack this relationship, but results might suggest that AI/AN communities may feature resilient and protective attributes, moderating the amount of disability experienced in rural AI/AN communities.

Exploring environmental measures in disability: Using Google Earth and Street View to conduct remote assessments of access and participation in urban and rural communities.

The Americans with Disabilities Act has been in place since 1990. Yet, we still do not know the actual levels of accessibility in the nation, how access varies across communities or over time, or how it influences participation in community life. The present two studies explored the use of Google Earth (GE) and Google Street View (GSV) imagery as a database for examining the accessibility of rural and urban cities and towns in the United States. We developed procedures for selecting places in a community to observe multiple access features. Study 1 reports the findings from assessments of 25 communities across 17 states. We observed ≈50,000 m (31 miles) of pathways through the observed places. The Combined Access Score (CAS) averaged 65% across these communities. In Study 2, we evaluated 22 towns and cities in a large rural state. We observed ≈77,000 m (48 miles) of pathways through the Central Business Districts observed as core areas connecting people to community life. The CAS averaged 83.9% across these communities. We noted a Rural Access Penalty (RAP), such that rural areas tended to be less accessible, leading to less community participation. The method for using GSV to examine accessibility is discussed. This study demonstrates an inexpensive and reliable method for evaluating the accessibility of communities and participation in them. Future research should be conducted to gather a larger sample of communities in order to create a baseline from which to monitor changes in accessibility of infrastructure over time.

Hypoxia-Mediated ATF4 Induction Promotes Survival in Detached Conditions in Metastatic Murine Mammary Cancer Cells.

Regions of hypoxia are common in solid tumors and drive changes in gene expression that increase risk of cancer metastasis. Tumor cells must respond to the stress of hypoxia by activating genes to modify cell metabolism and antioxidant response to improve survival. The goal of the current study was to determine the effect of hypoxia on cell metabolism and markers of oxidative stress in metastatic (metM-Wntlung) compared with nonmetastatic (M-Wnt) murine mammary cancer cell lines. We show that hypoxia induced a greater suppression of glutamine to glutamate conversion in metastatic cells (13% in metastatic cells compared to 7% in nonmetastatic cells). We also show that hypoxia increased expression of genes involved in antioxidant response in metastatic compared to nonmetastatic cells, including glutamate cysteine ligase catalytic and modifier subunits and malic enzyme 1. Interestingly, hypoxia increased the mRNA level of the transaminase glutamic pyruvic transaminase 2 (Gpt2, 7.7-fold) only in metM-Wntlung cells. The change in Gpt2 expression was accompanied by transcriptional (4.2-fold) and translational (6.5-fold) induction of the integrated stress response effector protein activating transcription factor 4 (ATF4). Genetic depletion ATF4 demonstrated importance of this molecule for survival of hypoxic metastatic cells in detached conditions. These findings indicate that more aggressive, metastatic cancer cells utilize hypoxia for metabolic reprogramming and induction of antioxidant defense, including activation of ATF4, for survival in detached conditions.

Identification of Aloe-derived natural products as prospective lead scaffolds for SARS-CoV-2 main protease (Mpro) inhibitors.

In the past two years, the COVID-19 pandemic has caused over 5 million deaths and 250 million infections worldwide. Despite successful vaccination efforts and emergency approval of small molecule therapies, a diverse range of antivirals is still needed to combat the inevitable resistance that will arise from new SARS-CoV-2 variants. The main protease of SARS-CoV-2 (Mpro) is an attractive drug target due to the clinical success of protease inhibitors against other viruses, such as HIV and HCV. However, in order to combat resistance, various chemical scaffolds need to be identified that have the potential to be developed into potent inhibitors. To this end, we screened a high-content protease inhibitor library against Mproin vitro, in order to identify structurally diverse compounds that could be further developed into antiviral leads. Our high-content screening efforts retrieved 27 hits each with > 50% inhibition in our Mpro FRET assay. Of these, four of the top inhibitor compounds were chosen for follow-up due to their potency and drugability (Lipinski's rules of five criteria): anacardic acid, aloesin, aloeresin D, and TCID. Further analysis via dose response curves revealed IC50 values of 6.8 µM, 38.9 µM, 125.3 µM, and 138.0 µM for each compound, respectively. Molecular docking studies demonstrated that the four inhibitors bound at the catalytic active site of Mpro with varying binding energies (-7.5 to -5.6 kcal/mol). Furthermore, Mpro FRET assay kinetic studies demonstrated that Mpro catalysis is better represented by a sigmoidal Hill model than the standard Michaelis-Menten hyperbola, indicating substantial cooperativity of the active enzyme dimer. This result suggests that the dimerization interface could be an attractive target for allosteric inhibitors. In conclusion, we identified two closely-related natural product compounds from the Aloe plant (aloesin and aloeresin D) that may serve as novel scaffolds for Mpro inhibitor design and additionally confirmed the strongly cooperative kinetics of Mpro proteolysis. These results further advance our knowledge of structure-function relationships in Mpro and offer new molecular scaffolds for inhibitor design.

Genetic analysis of the human microglial transcriptome across brain regions, aging and disease pathologies.

Microglia have emerged as important players in brain aging and pathology. To understand how genetic risk for neurological and psychiatric disorders is related to microglial function, large transcriptome studies are essential. Here we describe the transcriptome analysis of 255 primary human microglial samples isolated at autopsy from multiple brain regions of 100 individuals. We performed systematic analyses to investigate various aspects of microglial heterogeneities, including brain region and aging. We mapped expression and splicing quantitative trait loci and showed that many neurological disease susceptibility loci are mediated through gene expression or splicing in microglia. Fine-mapping of these loci nominated candidate causal variants that are within microglia-specific enhancers, finding associations with microglial expression of USP6NL for Alzheimer's disease and P2RY12 for Parkinson's disease. We have built the most comprehensive catalog to date of genetic effects on the microglial transcriptome and propose candidate functional variants in neurological and psychiatric disorders.

Thermo-sensitivity and erosion of chitosan crosslinked poly[N-isopropylacrylamide-co-(acrylic acid)-co-(methyl methacrylate)] hydrogels for application to the inferior fornix.

Thermo-gels based on chitosan crosslinked poly(N-isopropylacrylamide) were developed as alternatives to conventional eye drops for the sustained release of ketotifen fumarate in the treatment of allergic conjunctivitis. The thermo-gelling properties of the base polymer were altered prior to crosslinking with chitosan by incorporation of the hydrophilic and hydrophobic comonomers acrylic acid and methyl methacrylate respectively. Varying amounts of chitosan were incorporated by ionic interaction to produce polyelectrolyte complexes or by carbodiimide chemistry to produce covalently crosslinked networks. The lower critical solution temperature of all the chitosan crosslinked thermo-gels produced was below the surface temperature of the eye. All the chitosan crosslinked thermo-gels were found to have greater than 80% equilibrium water contents following gelation. The method and amount of chitosan incorporation allowed for tailor-ability of material rheologic properties, with full degradation occurring over a one-to-four-day period, and tailorable rates of release of 40-60% of the loaded allergy medication ketotifen fumarate. The chitosan crosslinked thermo-gels were demonstrated to be nontoxic both in vitro and in vivo. It was demonstrated that the synthesized materials could be applied to the inferior fornix of eye, sustaining a multiple day release of ketotifen fumarate, as an alternative to conventional eyedrops. STATEMENT OF SIGNIFICANCE: Topical eyedrops are the main treatment modality for anterior ocular conditions. However, due to the natural clearance mechanisms of the eye, topical eyedrops are well established to be largely ineffective as a method of drug delivery. Herein, we investigate a method of altering thermo-gel properties of an n-isopropylacrylamide based polymer to enable the incorporation of greater amounts of chitosan by different methods of crosslinking. By controlling the synthesis parameters, final material properties can be tailored to impart ideal spreading, retention on the eye, and the rate of degradation and drug release over several days. This work also focuses on studying the rheological properties of the chitosan crosslinked thermo-gels which has not been investigated previously.

Polymer-free corticosteroid dimer implants for controlled and sustained drug delivery.

Polymeric drug carriers are widely used for providing temporal and/or spatial control of drug delivery, with corticosteroids being one class of drugs that have benefitted from their use for the treatment of inflammatory-mediated conditions. However, these polymer-based systems often have limited drug-loading capacity, suboptimal release kinetics, and/or promote adverse inflammatory responses. This manuscript investigates and describes a strategy for achieving controlled delivery of corticosteroids, based on a discovery that low molecular weight corticosteroid dimers can be processed into drug delivery implant materials using a broad range of established fabrication methods, without the use of polymers or excipients. These implants undergo surface erosion, achieving tightly controlled and reproducible drug release kinetics in vitro. As an example, when used as ocular implants in rats, a dexamethasone dimer implant is shown to effectively inhibit inflammation induced by lipopolysaccharide. In a rabbit model, dexamethasone dimer intravitreal implants demonstrate predictable pharmacokinetics and significantly extend drug release duration and efficacy (>6 months) compared to a leading commercial polymeric dexamethasone-releasing implant.