Hypertrophic scars (HS) represent a significant clinical challenge due to their complex pathophysiology and resistance to conventional therapies, often resulting in persistent symptoms such as itching, pain, and impaired joint mobility that compromise patients' quality of life. Current treatment modalities, including compression therapy, pharmacological agents, radiation, silicone gel, and laser therapies, have faced limitations primarily due to inadequate drug penetration into the dense fibrotic scar tissue. In this context, microneedle-mediated controlled delivery systems have emerged as a promising pharmaceutical platform to enhance localized and sustained delivery of therapeutic agents, including small-molecule drugs, biologic proteins, small interfering RNA, and living cells, directly into HS. This article critically reviews the biological and formulation-related challenges associated with transdermal delivery in scar tissue and highlights recent innovations in microneedle design, material selection, and drug-loading techniques tailored for controlled release applications. Furthermore, it discusses the integration of proteins and cell-based therapies within microneedle platforms and their potential to modulate scar remodeling and inflammation. By addressing current limitations and exploring cutting-edge technologies, this review article aims to guide the development of effective microneedle-mediated strategies for pharmaceutical intervention in hypertrophic scar management.

Hypertrophic scars (HS) are pathological cutaneous scars characterized by excessive collagen deposition and fibrosis. Intralesional glucocorticoid injections remain the standard treatment for HS, but it is often associated with side effects. In this study, we developed a novel silk fibroin microneedle (SF-MN) loaded with prednisone for localized delivery and glucocorticoid metabolism. The SF-MNs were fabricated using 10 % (w/v) silk fibroin. Prednisone-loaded SF-MNs were characterized by SEM and evaluated for biocompatibility, mechanical strength, and preclinical efficacy. Overall, the results demonstrated that the SF-MN enhanced local expression of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), a specific enzyme that converting inactive glucocorticoids to its active form. SF-MN also achieved sustained in vitro release of prednisone over 7 days. Once released into local tissue, prednisone was rapidly converted to its active form, prednisolone. In the animal study, prednisone-SF-MNs effectively prevented scar formation during wound healing. Moreover, in the HS model, the prednisone-SF-MN accelerated scar remodelling, resulting in smaller scar size and decreased fibrosis. This targeted delivery strategy optimizes local glucocorticoid metabolism, enhance drug penetration, and minimize side effects associated with active glucocorticoid administration. These findings highlight the potential of SF microneedle-based drug delivery for improving HS treatment and support its future clinical translation.

Background:Excessive scarring and fibrosis are the most severe and common complications of burn injury. Prolonged exposure to high levels of glucocorticoids detrimentally impacts on skin, leading to skin thinning and impaired wound healing. Skin can generate active glucocorticoids locally through expression and activity of the 11β-hydroxysteroid dehydrogenase type 1 enzyme (11β-HSD1). We hypothesised that burn injury would induce 11β-HSD1 expression and local glucocorticoid metabolism, which would have important impacts on wound healing, fibrosis and scarring. We additionally proposed that pharmacological manipulation of this system could improve aspects of post-burn scarring.Methods:Skin 11β-HSD1 expression in burns patients and mice was examined. The impacts of 11β-HSD1 mediating glucocorticoid metabolism on burn wound healing, scar formation and scar elasticity and quality were additionally examined using a murine 11β-HSD1 genetic knockout model. Slow-release scaffolds containing therapeutic agents, including active and inactive glucocorticoids, were developed and pre-clinically tested in mice with burn injury.Results:We demonstrate that 11β-HSD1 expression levels increased substantially in both human and mouse skin after burn injury. 11β-HSD1 knockout mice experienced faster wound healing than wild type mice but the healed wounds manifested significantly more collagen deposition, tensile strength and stiffness, features characteristic of excessive scarring. Application of slow-release prednisone, an inactive glucocorticoid, slowed the initial rate of wound closure but significantly reduced post-burn scarring via reductions in inflammation, myofibroblast generation, collagen production and scar stiffness.Conclusions:Skin 11β-HSD1 expression is a key regulator of wound healing and scarring after burn injury. Application of an inactive glucocorticoid capable of activation by local 11β-HSD1 in skin slows the initial rate of wound closure but significantlyimproves scar characteristics post burn injury.

Endogenous glucocorticoids and commonly used oral glucocorticoids have the property of existing in an inactive and active form in vivo. The inactive form can be converted back to the active form, or 'recycled' in cells and tissues that express the 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) enzyme. This recycling provides an important contribution to the action of glucocorticoids. This review examines the literature relating to the importance of 11β-HSD1 activity during glucocorticoid treatment, with an emphasis on studies examining bone and joint disease and the ability of glucocorticoids to suppress inflammatory damage in models of arthritis. Animal models with global or selective deletion of 11β-HSD1 have determined the extent to which this recycling is important in normal physiology and during treatment with oral glucocorticoids. These studies demonstrate that 11β-HSD1-mediated recycling of inactive glucocorticoids has a substantial action and indeed is responsible for the majority of the effects of orally administered glucocorticoids on a range of tissues. Importantly, the anti-inflammatory actions of glucocorticoids appear largely through this mechanism such that mice that lack 11β-HSD1 are resistant to the anti-inflammatory actions of glucocorticoids. The recognition that to a large extent the circulating inactive counterpart of these glucocorticoids is more important to anti-inflammatory effects than the active glucocorticoid presents novel opportunities to more selectively target glucocorticoids to tissues or to reduce the likely side effects.

Objectives: Knowledge is limited regarding the adverse effects of therapeutic glucocorticoids on pediatric mental health outcomes. Glucocorticoid-induced psychosis (GIP) is a rare but severe side effect of high-dose glucocorticoid therapy in children and adolescents. This study identified reported pediatric cases of GIP, based on DSM-5 criteria, and defined its presentation, treatments, and outcomes.Methods: A systematic review was completed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, including pediatric patients with incident psychosis following glucocorticoid treatment. Patient demographics, clinical presentation, interventions, outcomes, and long-term management were extracted from individual cases.Results: Of 1131 articles screened, 28 reports were included, comprising of 31 patients. The mean age was 13 years, and 61% of patients were male. The most common medical illnesses requiring administration of high dose glucocorticoids were asthma (23%) and acute lymphoblastic leukemia (23%). The most common glucocorticoid used was prednisone (35%), and most patients (91%) received doses greater than or equal to 40 mg/day of prednisone. The range of time to symptom onset was 1 day to 7 months. Hallucinations alone (45%) were the most reported feature of GIP. Glucocorticoids were discontinued in 52% of cases, reduced in dosage in 32%, and 81% of affected patients were prescribed psychotropic medications. Long-term management plans and prophylactic psychotropic use were not mentioned in 52% of cases. Symptoms resolved in 90% of patients, and the majority (71%) had no recurrence of psychiatric symptoms.Conclusions: GIP can generally be managed by tapering the causative agent with adjunctive second-generation antipsychotics if psychotic symptoms persist. All patients in this review had complete resolution or improvement of their psychotic symptoms; however, there is likely reporting bias due to the expected underreporting of negative outcomes. Managing clinicians must take a circumspect approach when prescribing high-dose glucocorticoids to minimize the risk of serious but preventable side effects.

Context The causative link between circulating glucocorticoid excess and osteoporosis is well-established. The enzyme 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) increases local cortisol production, is expressed in human osteoblasts and its activity increases with age. We hypothesized that local 11 beta-HSD1 might mediate an age-related decrease in bone formation and that selective 11 beta-HSD1 inhibition may enhance bone formation. Methods A twin-centre phase II randomized, double-blind, placebo-controlled trial of 90 days' treatment with AZD4017 (a selective 11 beta-HSD1 inhibitor) was conducted. 55 post-menopausal women with osteopenia were recruited. Participants received 400mg twice daily of oral AZD4017 compared to matched placebo over 90 days. The primary outcome measure was the impact on the bone formation marker, osteocalcin. Secondary objectives included correlation with 11 beta-HSD1 activity. Results At 90 days the levels of osteocalcin did not differ between the treatment groups, active [mean 22.3 (SD 8.6) ng/ml, n=22] and placebo [21.7 (SD 9.2) ng/ml, n=24], with an adjusted for baseline treatment effect of 0.95 (95% CI: -2.69, 4.60). The results from the urinary [THF+alloTHF]/THE ratio (index of 11 beta-Fispi activity) and the urinary cortisol/cortisone ratio (index of 11 beta-HSD2 activity), confirmed a >90% inhibition of 11 beta-HSD1 but no change in activity of 1113-HSD2. Conclusion This trial demonstrates that AZD 4017 selectively inhibits 11 beta-HSD1 activity in vivo in a safe and reversible manner. Following treatment for 90 days there is no effect on bone formation, indicating that the relative impairment of bone mineral density in post-menopausal women is not mediated by local intracellular production of cortisol, under normal physiological concentrations.

Therapeutic glucocorticoids (GCs) are powerful anti-inflammatory tools in the management of chronic inflammatory diseases such as rheumatoid arthritis (RA). However, their actions on bone in this context are complex. The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is a mediator of the anti-inflammatory actions of therapeutic glucocorticoids (GCs) in vivo. In this study we delineate the role of 11β-HSD1 in the effects of GC on bone during inflammatory polyarthritis. Its function was assessed in bone biopsies from patients with RA and osteoarthritis, and in primary osteoblasts and osteoclasts. Bone metabolism was assessed in the TNF-tg model of polyarthritis treated with oral GC (corticosterone), in animals with global (TNF-tg11βKO), mesenchymal (including osteoblast) (TNF-tg11βflx/tw2cre) and myeloid (including osteoclast) (TNF-tg11βflx/LysMcre) deletion. Bone parameters were assessed by micro-CT, static histomorphometry and serum metabolism markers. We observed a marked increase in 11β-HSD1 activity in bone in RA relative to osteoarthritis bone, whilst the pro-inflammatory cytokine TNFα upregulated 11β-HSD1 within osteoblasts and osteoclasts. In osteoclasts, 11β-HSD1 mediated the suppression of bone resorption by GCs. Whilst corticosterone prevented the inflammatory loss of trabecular bone in TNF-tg animals, counterparts with global deletion of 11β-HSD1 were resistant to these protective actions, characterised by increased osteoclastic bone resorption. Targeted deletion of 11β-HSD1 within osteoclasts and myeloid derived cells partially reproduced the GC resistant phenotype. These data reveal the critical role of 11β-HSD1 within bone and osteoclasts in mediating the suppression of inflammatory bone loss in response to therapeutic GCs in chronic inflammatory disease.

Wound healing is a complex process involving multiple independent and overlapping sequential physiological mechanisms. In addition to cutaneous injury, a severe burn stimulates physiological derangements that induce a systemic hypermetabolic response resulting in impaired wound healing. Topical application of the anti-androgen drug, flutamide accelerates cutaneous wound healing, whereas paradoxically systemic dihydrotestosterone (DHT) improves burn wound healing. We developed and characterized a PCL scaffold that is capable of controlled release of androgen (DHT) and anti-androgen (F) individually or together. This study aims to investigate whether local modification of androgen actions has an impact on burn injury wound healing. In a full-thickness burn wound healing, mouse model, DHT/F-scaffold showed a significantly faster wound healing compared with F-scaffold or DHT-scaffold. Histology analysis confirmed that DHT/F-scaffold exhibited higher re-epithelization, cell proliferation, angiogenesis, and collagen deposition. Dual release of DHT and F from PCL scaffolds promoted cell proliferation of human keratinocytes and alters the keratinocyte cell cycle. Lastly, no adverse effects on androgen-dependent organs, spleen and liver were observed. In conclusion, we demonstrated DHT plus F load PCL scaffolds accelerated burn wound healing when loading alone did not. These findings point to a complex role of androgens in burn wound healing and open novel therapeutic avenues for treating severe burn patients.

The role of tissue specific metabolism of endogenous glucocorticoids (GCs) in the pathogenesis of human disease has been a field of intense interest over the last 20 years, fuelling clinical trials of metabolism inhibitors in the treatment of an array of metabolic diseases. Localised pre-receptor metabolism of endogenous and therapeutic GCs by the 11β-hydroxysteroid dehydrogenase (11β-HSD) enzymes (which interconvert endogenous GCs between their inactive and active forms) are increasingly recognised as being critical in mediating both their positive and negative actions on bone homeostasis. In this review we explore the roles of endogenous and therapeutic GC metabolism by the 11β-HSD enzymes in the context of bone metabolism and bone cell function, and consider future strategies aimed at modulating this system in order to manage and treat various bone diseases.

Abstract Wound healing is a complex process involving four overlapping phases: haemostasis, inflammation, cell recruitment and matrix remodeling. In mouse models, surgical, pharmacological and genetic approaches targeting androgen actions in skin have shown that androgens increase interleukin-6 and tumor necrosis factor-α production and reduce wound re-epithelization and matrix deposition, retarding cutaneous wound healing. Similarly, clinical studies have shown that cutaneous wound healing is slower in men compared to women. However, in major burn injury, which triggers not only local wound-healing processes but also systemic hypermetabolism, the role of androgens is poorly understood. Recent studies have claimed that a synthetic androgen, oxandrolone, increases protein synthesis, improves lean body mass and shortens length of hospital stay. However, the possible mechanisms by which oxandrolone regulates major burn injury have not been reported. In this review, we summarize the current findings on the roles of androgens in cutaneous and major burn wound healing, as well as androgens as a potential therapeutic treatment option for patients with major burn injuries.

Glucocorticoids provide indispensable anti-inflammatory therapies. However, metabolic adverse effects including muscle wasting restrict their use. The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) modulates peripheral glucocorticoid responses through pre-receptor metabolism. This study investigates how 11β-HSD1 influences skeletal muscle responses to glucocorticoid therapy for chronic inflammation. We assessed human skeletal muscle biopsies from patients with rheumatoid arthritis and osteoarthritis for 11β-HSD1 activity ex vivo. Using the TNF-α-transgenic mouse model (TNF-tg) of chronic inflammation, we examined the effects of corticosterone treatment and 11β-HSD1 global knock-out (11βKO) on skeletal muscle, measuring anti-inflammatory gene expression, muscle weights, fiber size distribution, and catabolic pathways. Muscle 11β-HSD1 activity was elevated in patients with rheumatoid arthritis and correlated with inflammation markers. In murine skeletal muscle, glucocorticoid administration suppressed IL6 expression in TNF-tg mice but not in TNF-tg11βKO mice. TNF-tg mice exhibited reductions in muscle weight and fiber size with glucocorticoid therapy. In contrast, TNF-tg11βKO mice were protected against glucocorticoid-induced muscle atrophy. Glucocorticoid-mediated activation of catabolic mediators (FoxO1, Trim63) was also diminished in TNF-tg11βKO compared to TNF-tg mice. In summary, 11β-HSD1 knock-out prevents muscle atrophy associated with glucocorticoid therapy in a model of chronic inflammation. Targeting 11β-HSD1 may offer a strategy to refine the safety of glucocorticoids.

OBJECTIVE:Aging and chronic glucocorticoid excess share a number of critical features, including the development of central obesity, insulin resistance and osteoporosis. Previous studies have shown that skeletal glucocorticoid signalling increases with aging and that osteoblasts mediate the detrimental skeletal and metabolic effects of chronic glucocorticoid excess. Here, we investigated whether endogenous glucocorticoid action in the skeleton contributes to metabolic dysfunction during normal aging.METHODS:Mice lacking glucocorticoid signalling in osteoblasts and osteocytes (HSD2OB/OCY-tg mice) and their wild-type littermates were studied until 3, 6, 12 and 18 months of age. Body composition, adipose tissue morphology, skeletal gene expression and glucose/insulin tolerance were assessed at each timepoint. Leptin sensitivity was assessed by arcuate nucleus STAT3 phosphorylation and inhibition of feeding following leptin administration. Tissue-specific glucose uptake and adipose tissue oxygen consumption rate were also measured.RESULTS:As they aged, wild-type mice became obese and insulin-resistant. In contrast, HSD2OB/OCY-tg mice remained lean and insulin-sensitive during aging. Obesity in wild-type mice was due to leptin resistance, evidenced by an impaired ability of exogenous leptin to suppress food intake and phosphorylate hypothalamic STAT3, from 6 months of age onwards. In contrast, HSD2OB/OCY-tg mice remained leptin-sensitive throughout the study. Compared to HSD2OB/OCY-tg mice, leptin-resistant wild-type mice displayed attenuated sympathetic outflow, with reduced tyrosine hydroxylase expression in both the hypothalamus and thermogenic adipose tissues. Adipose tissue oxygen consumption rate declined progressively in aging wild-type mice but was maintained in HSD2OB/OCY-tg mice. At 18 months of age, adipose tissue glucose uptake was increased 3.7-fold in HSD2OB/OCY-tg mice, compared to wild-type mice.CONCLUSIONS:Skeletal glucocorticoid signalling is critical for the development of leptin resistance, obesity and insulin resistance during aging. These findings underscore the skeleton's importance in the regulation of body weight and implicate osteoblastic/osteocytic glucocorticoid signalling in the aetiology of aging-related obesity and metabolic disease.

Objective: To estimate the level of dispensing of oral corticosteroids (OCS) for managing asthma in Australia, with a particular focus on the cumulative dispensing of doses associated with long term toxicity (>= 1000 mg prednisolone-equivalent). Design: Retrospective cohort study; analysis of 10% random sample of Pharmaceutical Benefits Scheme (PBS) dispensing data. Participants, setting: People aged 12 years or more treated for asthma during 2014-2018, according to dispensing of controller inhaled corticosteroids (ICS). Main outcome measures: Number of people dispensed OCS for managing asthma during 2014-2018; proportion who were cumulatively dispensed at least 1000 mg prednisolone-equivalent. The secondary outcome was the number of people dispensed at least 1000 mg prednisolone-equivalent during 2018, stratified by inhaler controller dose and use. Results: 124 011 people had been dispensed at least two prescriptions of ICS during 2014-2018 and met the study definition for asthma, of whom 64 112 (51.7%) had also been dispensed OCS, including 34 580 (27.9% of the asthma group) cumulatively dispensed 1000 mg prednisolone-equivalent or more. Of 138 073 people dispensed OCS at this level, 68 077 (49%) were patients with airway diseases. Dispensing of diabetes and osteoporosis medications was more common for people cumulatively dispensed 1000 mg prednisolone-equivalent or more. During 2018, 4633 people with asthma using high dose ICS controllers were dispensed 1000 mg prednisolone-equivalent or more, for 2316 of whom (50%) controller use was inadequate. Conclusions: Cumulative exposure to OCS in Australia reaches levels associated with toxicity in one-quarter of patients with asthma using ICS. Cumulative dispensing of potentially toxic OCS amounts often accompanies inadequate inhaler controller dispensing. Better approaches are needed to improve adherence to controller therapy, improve outcomes for people with asthma, and to minimise the use and toxicity of OCS.

Androgens have been known to inhibit cutaneous wound healing in men and male mice. However, in children with major burn injuries, a synthetic androgen was reported clinically to improve wound healing. The aim of this study is to investigate the role of dihydrotestosterone (DHT) as a new therapeutic approach in treating major burn injury. In the present study, mice received systemic androgen treatment post major burn injury. Wound healing rate and body weight were monitored over 21 days. The serum level of inflammatory cytokines/chemokines were measured using multiplex immunoassays. In addition, splenocyte enumeration was performed by flow cytometry. Healing phases of inflammation, re-epithelialization, cell proliferation and collagen deposition were also examined. In results, DHT treated mice lost less weight and displayed accelerated wound healing but has no impact on hypermetabolism. Mice, after burn injury, displayed acute systemic inflammatory responses over 21 days. DHT treatment shortened the systemic inflammatory response with reduced splenic weight and monocyte numbers on day 14 and 21. DHT treatment also reduced wound infiltrating macrophage numbers. In conclusion, DHT treatment facilitates local wound healing by accelerating the resolution of inflammation, but not through alterations of post-burn hypermetabolic response.

Glucocorticoids are widely used for their unsurpassed antiinflammatory and immunomodulatory effects. While these beneficial effects can hardly be overestimated, the therapeutic use of glucocorticoids is almost always limited by significant adverse outcomes such as osteoporosis, diabetes, and abnormal fat accrual. In order to understand the pathogenesis of glucocorticoid-induced osteoporosis, it is important to realize that the actions of glucocorticoids on bone and mineral metabolism are strongly dose and time dependent. Thus, at physiological concentrations, glucocorticoids are key regulators of mesenchymal cell differentiation, bone development, and skeletal homeostasis, with additional regulatory roles in renal and intestinal calcium handling. At supraphysiological concentrations, however, glucocorticoids affect the very same systems in completely different and often unfavorable ways. For many years, these anabolic and catabolic actions of glucocorticoids on bone were considered paradoxical. This chapter discusses recent advances in our understanding of the mechanisms underlying the physiology and pathophysiology of glucocorticoid action on the skeleton and provides an account of current and future management strategies for glucocorticoid-induced osteoporosis.

Therapeutic glucocorticoids have been widely used in rheumatic diseases since they became available over 60 years ago. Despite the advent of more specific biologic therapies, a notable proportion of individuals with chronic rheumatic diseases continue to be treated with these drugs. Glucocorticoids are powerful, broad-spectrum anti-inflammatory agents, but their use is complicated by an equally broad range of adverse effects. The specific cellular mechanisms by which glucocorticoids have their therapeutic action have been difficult to identify, and attempts to develop more selective drugs on the basis of the action of glucocorticoids have proven difficult. The actions of glucocorticoids seem to be highly cell-type and context dependent. Despite emerging data on the effect of tissue-specific manipulation of glucocorticoid receptors in mouse models of inflammation, the cell types and intracellular targets of glucocorticoids in rheumatic diseases have not been fully identified. Although showing some signs of decline, the use of systemic glucocorticoids in rheumatology is likely to continue to be widespread, and careful consideration is required by rheumatologists to balance the beneficial effects and deleterious effects of these agents. Glucocorticoids are anti-inflammatory therapies commonly used in rheumatology, but have wide-ranging adverse effects. Understanding the pharmacokinetic properties and mechanisms of action of glucocorticoids could inform in the development of novel therapies with fewer adverse effects.

Clinical EndocrinologyVolume 91, Issue 3 p. 372-373 COMMENTARY Demystifying adrenal dysfunction in severe illness Mark S. Cooper, Corresponding Author Mark S. Cooper mark.cooper@sydney.edu.au orcid.org/0000-0003-3112-7728 Concord Clinical School, ANZAC Research Institute, The University of Sydney, Concord Hospital, Concord, New South Wales, Australia Correspondence Mark S Cooper, Concord Clinical School, ANZAC Research Institute, The University of Sydney, Concord Hospital, Concord, NSW 2139, Australia. Email: mark.cooper@sydney.edu.auSearch for more papers by this author Mark S. Cooper, Corresponding Author Mark S. Cooper mark.cooper@sydney.edu.au orcid.org/0000-0003-3112-7728 Concord Clinical School, ANZAC Research Institute, The University of Sydney, Concord Hospital, Concord, New South Wales, Australia Correspondence Mark S Cooper, Concord Clinical School, ANZAC Research Institute, The University of Sydney, Concord Hospital, Concord, NSW 2139, Australia. Email: mark.cooper@sydney.edu.auSearch for more papers by this author First published: 10 July 2019 https://doi.org/10.1111/cen.14054 Please see related paper on pages [374–382] of this issue. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume91, Issue3September 2019Pages 372-373 RelatedInformation

Accurate measurement of circulating glucocorticoid concentrations in rodents is often hampered by the stress-related activation of the hypothalamic-pituitaryadrenal axis during animal handling. The present study aims to identify methods of blood collection associated with minimal stress and thus artificial increases in plasma glucocorticoid levels. Using two strains of mice, we evaluated common laboratory methods of non-terminal (tail blood sampling with or without restraint; retro-orbital puncture) and terminal blood collection (cardiac puncture) and their immediate and prolonged effect on plasma corticosterone levels. Compared to retro-orbital and cardiac puncture, mice from both the unrestrained and restrained tail snip collection groups displayed the lowest plasma corticosterone levels in both mouse strains. Plasma corticosterone levels in samples obtained from retro-orbital and cardiac puncture collection were up to twenty times higher than those measured in mice undergoing blood collection via tail snip. Repeat tail snip collections (every 30 min for 120 min, or once after 120 min) revealed sustained hypercortisolaemia, compared to the initial collection. We conclude that blood sampling via tail snip without restraint remains the gold-standard method of collection that is associated with minimal stress-related artefacts and hence feasible for single time point corticosterone analyses.

Previous studies demonstrated that endogenous glucocorticoid signaling in osteoblasts promotes inflammation in murine immune arthritis. The current study determined whether disruption of endogenous glucocorticoid signaling in chondrocytes also modulates the course and severity of arthritis. Tamoxifen-inducible chondrocyte-targeted glucocorticoid receptor-knockout (chGRKO) mice were generated by breeding GRflox/flox mice with tamoxifen-inducible collagen 2a1 Cre (Col2a1-CreERT2) mice. Antigen-induced arthritis (AIA) and K/BxN serum transfer-induced arthritis (STIA) were induced in both chGRKO mice and their Cre-negative GRflox/flox littermates [wild type (WT)]. Arthritis was assessed by measurement of joint swelling and histology of joints collected at d 14. Neutrophil activity and gene expression patterns associated with cartilage damage were also evaluated. In both arthritis models clinical (joint swelling) and histologic indices of inflammatory activity were significantly greater in chGRKO than in WT mice. The STIA model was characterized by early up-regulation of CXCR2/CXCR2 ligand gene expression in ankle tissues, and significant and selective expansion of splenic CXCR2+ neutrophils in chGRKO arthritic compared to WT arthritic mice. At later stages, gene expression of enzymes involved in cartilage degradation was up-regulated in chGRKO but not WT arthritic mice. Therefore, we summarize that chondrocytes actively mitigate local joint inflammation, cartilage degradation and systemic neutrophil activity via a glucocorticoid-dependent pathway.-Tu, J., Stoner, S., Fromm, P. D., Wang, T., Chen, D., Tuckermann, J., Cooper, M. S., Seibel, M. J., Zhou, H. Endogenous glucocorticoid signaling in chondrocytes attenuates joint inflammation and damage.