Osteoid Osteoma of the Coracoid Process Presenting as Adhesive Capsulitis in a 10-Year-Old Male: A Case Report.

A 10-year-old male presented with symptoms in his right shoulder indicative of adhesive capsulitis. Radiographic films did not demonstrate any osseous abnormalities. Magnetic resonance imaging demonstrated the presence of an eccentric lesion within the coracoid process consistent with an osteoid osteoma. Six months after surgical removal the patient is back to full activities. For the pediatric population, surgeons must always consider diagnoses that could alter a patient's growth or result in long-term disability. In particular, an atypical presentation of musculoskeletal disease in a pediatric patient presenting with a disease that typically is seen in the older population warrants further workup.

Coracoclavicular Ligament Reconstruction Using TightRope for Delayed Grade III Acromioclavicular Joint Injury After Ipsilateral Diaphyseal Clavicle Fracture Fixation: Surgical Technique and Review of Current Literature.

Athletes commonly sustain high-energy direct impact injuries to the shoulder, with acromioclavicular joint (ACJ) injuries accounting for over half. Ipsilateral ACJ injury and diaphyseal clavicle fracture occur nearly 7% of the time. There is limited literature offering treatment suggestions for this unique injury pattern and limited evidence providing guidance to suggest which injury patterns should be treated operatively or nonoperatively. Here, we present successful treatment of a high-level athlete utilizing a Knotless TightRope XP placed through a superior clavicle plate with successful return to full activity at 6 months postoperation. The TightRope technique offers the ability to augment through a preexisting superior clavicular plate in a low-profile manner and promote easy suture tensioning to obtain and maintain reduction of the injured ACJ.

Outcomes following balloon tibioplasty versus conventional osteosynthesis techniques for Schatzker type III tibial plateau fractures: a systematic review.

INTRODUCTION: Schatzker type III fractures of the tibial plateau require elevation of the depressed portions to regain articular congruity. Balloon tibioplasty has been used as an alternative to conventional metal instruments for elevation of the lateral tibial plateau. This study compared functional outcomes following balloon tibioplasty or conventional osteosynthesis techniques in patients with type III fractures of the tibial plateau. MATERIALS AND METHODS: A systematic literature search was performed using PubMed, EMBASE, and Cochrane Library to identify studies published through March 29, 2021, pertaining to balloon tibioplasty or conventional osteosynthesis techniques for type III fractures. Non-human studies, opinion or editorial pieces, systematic reviews, case series (< 5 patients), and articles published in a non-English language were excluded. Primary outcomes were Rasmussen clinical score, range of motion, and Knee Society Score (KSS). A Joanna Briggs Institute (JBI) risk of bias assessment was performed for all studies. RESULTS: A total of 95 studies were identified, with 10 studies (and 132 total patients) meeting inclusion criteria: 1 study focused on balloon tibioplasty, 8 studies reported outcomes following conventional osteosynthesis, and 1 study compared outcomes of the two techniques. Mean follow-up times varied widely, from 4 to 76.3 months. Where reported, balloon tibioplasty resulted in good to excellent functional outcomes as indicated by Rasmussen clinical scores (mean 28.3 in a case series; mean 28.9 in a randomized controlled trial) and range of motion (≥ 140° in both studies) 1-2 years following surgery. KSS was not reported consistently enough for comparison. Studies ranged from low to high risk of bias according to the JBI assessment. CONCLUSIONS: Balloon tibioplasty can lead to excellent functional outcomes in patients with depression fractures of the lateral tibial plateau. More research is needed to directly compare outcomes following treatment with balloon tibioplasty or conventional osteosynthesis techniques.

An Assessment of the Impact of SARS-CoV-2 on a Level 1 Trauma Center Including Subgroup Analysis of Orthopedic Injuries and Mechanism of Injury.

Background and objective There is a paucity of medical literature describing the preparedness of hospital institutions to withstand the population effects of a pandemic. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), has had a global impact on all facets of medicine, which has ultimately affected the medical community in a significant manner. Furthermore, there is a scarcity of research regarding the effects of COVID-19 on trauma and acute care surgery injury and admission rates. We conducted this study to examine the effects of the COVID-19 pandemic on both pediatric and adult trauma admissions, injury types, and mechanisms of injury. Materials and methods Data from the Trauma Registry was extracted for all adult (>15 years) and pediatric (<15 years) patients who consulted trauma surgery, acute care surgery, or orthopedic surgery at our center in the year immediately prior to the pandemic (March 1, 2019-February 29, 2020) and during the COVID-19 pandemic (March 1, 2020-February 28, 2021). Patient demographics, cause of injury, injury type and mechanism, and procedures performed were recorded. Results We documented a 4.2% increase in adult encounters compared to the preceding year. There was a significant difference in the distribution of mechanism of injury of adult patients between the two time periods, with the most changes seen in motor-vehicle auto, gunshot, and other vehicle injuries. However, no significant difference was seen in trauma type or intent (assault, self-inflicted, unintentional). Pediatric encounters increased by 6.4% during the COVID-19 pandemic compared to the pre-COVID-19 period. Overall, there was no detectable association between the distribution of encounters by the mechanism of injury and the time period for pediatric encounters. Conclusion This retrospective review of trauma encounters through both pre-COVID-19 and COVID-19 periods outlines the differences in factors such as demographics, injury mechanisms, and injury types between the two time periods. Overall, we expected a decrease in orthopedic-related trauma admissions during the COVID-19 pandemic; however, there was actually an increase of 4.1% in adult encounters and that of 6.4% in pediatric encounters. Our study lays out possible trends in injury patterns that can be correlated with the COVID-19 pandemic and the lockdown period. This information is useful for the healthcare system in that it demonstrates that resources should not be cut down or removed from surgical specialties. At level I facilities, resources need to be allocated for and continued to be provided to emergency rooms and operative services, including supplies and staffing. These departments need to be well-equipped to handle an increased number of trauma patients.

Does shoulder stability differ with or without subscapularis repair after primary reverse total shoulder arthroplasty? A systematic review.

The use of reverse total shoulder arthroplasty (RTSA) has expanded from its original indication as a rotator cuff arthropathy treatment to include a large variety of pathologies. A frequently reported complication with this surgery is postoperative shoulder instability with reported incidence varying widely from 2.3 to 38%. The etiology for this instability is broad and includes prosthesis design, mechanical impingement, surgical technique, and axillary/deltoid function. A PROSPERO-registered systematic review was performed utilizing PRISMA guidelines using Cochrane, PUBMED, Embase, and Eline. Of the 1442 studies initially identified, 7 studies met all inclusion criteria, all of which were level III or IV evidence. All 7 studies evaluated postoperative instability, but no study reported a statistically significant difference in instability rates between the groups. Dislocations occurred in 5 patients (5/679, 0.7%) with subscapularis repair and 8 patients (8/527, 1.5%) without repair. A nonsignificant difference in the risk of instability for surgeries with repair compared to surgeries without repair was found (overall risk difference: 0.01, random effects 95% confidence interval: -0.00 to 0.02, P = .11). This review suggests no difference in postoperative shoulder instability rates between patients that underwent primary RTSA with or without subsequent repair of the subscapularis tendon. Interestingly, one study comparing implants with a medialized or nonlateralized implant showed a significantly increased rate of dislocation with the medialized group compared to the lateralized group. When these groups were then stratified based on subscapularis repair status, there was no increased risk with a nonrepaired tendon. This study suggests that implant design may have more influence on the stability of RTSA than subscapularis status. However, overall, there does appear to be a trend suggesting improved postoperative clinical outcomes and active range of motion for patients with a subscapularis repair vs. without a repair. Further research is needed to better elucidate the ideal combination of surgical technique and implant design to minimize postoperative glenohumeral joint instability while optimizing postoperative clinical outcomes and range of motion after primary RTSA.

The effect of instrumentation staging on patient outcomes in pyogenic vertebral osteomyelitis: A systematic review.

BACKGROUND: Pyogenic vertebral osteomyelitis is a bacterial infection of the vertebral body that is often treatable with antibiotics, but some cases require additional surgical debridement of the infected tissue. Instrumentation is often utilized for stabilization of the spine as part of the surgical treatment, but controversy remains over the relative risks and benefits of acute instrumentation performed simultaneously with debridement versus delayed instrumentation performed days or weeks after debridement. The purpose of this review was to investigate the relative effects of acute and delayed instrumentation in treatment for pyogenic vertebral osteomyelitis on patient outcomes. METHODS: A PRISMA-compliant systematic literature review was conducted to identify studies published between January 1, 1997 and July 23, 2021. Studies were screened for pre-defined inclusion and exclusion criteria. The primary outcome of interest was reinfection. Other outcomes of interest included neurological status, pain, progression of kyphosis, fusion, hardware failure, length of hospitalization, and mortality at two years. Due to the limited multi-armed studies available that distinguish between patients with acute and delayed instrumentation, inferential statistics were not performed, and data are expressed as descriptive statistics. RESULTS: A total of 9 studies met our inclusion criteria, comprising 299 patients, including 113 (37.8%) with surgical treatment without fixation, 138 (46.2%) with acute instrumentation, and 48 (16.1%) with delayed instrumentation. Reinfection rates were 60.0% (15/25) for surgical treatment without fixation, 28.6% (2/7) for the acute instrumentation, and 14.3% (1/7) for the delayed instrumentation group. Pain was present after surgery in 52.0% (13/25) of the surgical treatment without fixation group, 14.3% (1/7) of the acute instrumentation group, and 0% (0/7) of the delayed instrumentation group. CONCLUSIONS: No major differences in patient outcomes were apparent between acute and delayed instrumentation groups. Further research is needed to determine whether instrumentation staging has a significant impact on patient outcomes.

Tranexamic acid dosing strategies and blood loss reduction in multilevel spine surgery: A systematic review and network meta-analysis: Tranexamic acid for multilevel spine surgery.

BACKGROUND: For adults undergoing complex, multilevel spinal surgery, tranexamic acid (TXA) is an antifibrinolytic agent used to reduce blood loss. The optimal dosing of intravenous TXA remains unclear. This systematic review and meta-analysis compare various dosing regimens of intravenous TXA used in patients undergoing multilevel spine surgery (≥2 levels). METHODS: PubMed, Cochrane, and EMBASE databases were searched for English language studies published January 2001 through May 2021 reporting use of TXA versus placebo for multilevel spine surgery. Primary outcomes of interest were intraoperative blood loss volume (BLV) and total BLV. A separate random effects model was fit for each outcome measure. Effect sizes were calculated as pooled mean differences (Diff) with corresponding 95% confidence intervals (CIs). Random effects network meta-analyses assessed whether the specific TXA dosing regimen influenced BLV. RESULTS: Seven studies with 441 patients were included for meta-analysis. Four different TXA dosing regimens were found: 1) 10 mg/kg + 1 mg/kg/h, 2) 10 mg/kg + 2 mg/kg/h, 3) 15 mg/kg, 4) 15 mg/kg + 1 mg/kg/h. Compared to placebo, patients treated with TXA had reduced intraoperative BLV (Diff = -185.0 ml; 95% CI: -302.1, -67.9) and reduced total BLV (Diff = -439.0 ml; 95% CI: -838.5, -39.6). No significant differences in intraoperative BLV among any of the TXA treatment groups was found. Patients given a TXA dose of 15 mg/kg + 1 mg/kg/h had significantly reduced total BLV in comparison to both placebo (Diff = -823.1 ml; 95% CI: -1249.8, -396.4) and a dose of 15 mg/kg (Diff = -581.2; 95% CI: -1106.8, -55.7). CONCLUSIONS: This study found that intravenous TXA is associated with reduced intraoperative and total BLV, but it remains unclear whether there is an optimal TXA dose. Additional trials directly comparing different TXA regimens and administration routes are needed.

Image-Based Profiling of Patient-Derived Pancreatic Tumor-Stromal Cell Interactions Within a Micropatterned Tumor Model.

Pancreatic cancer is one of the most aggressive cancers with a 5-year patient survival rate of 8.2% and limited availability of therapeutic agents to target metastatic disease. Pancreatic cancer is characterized by a dense stromal cell population with unknown contribution to the progression or suppression of tumor growth. In this study, we describe a microengineered tumor stromal assay of patient-derived pancreatic cancer cells to study the heterotypic interactions of patient pancreatic cancer cells with different types of stromal fibroblasts under basal and drug-treated conditions. The population dynamics of tumor cells in terms of migration and viability were visualized as a functional end point. Coculture with cancer-associated fibroblasts increased the migration of cancer cells when compared to dermal fibroblasts. Finally, we imaged the response of a bromodomain and extraterminal inhibitor on the viability of pancreatic cancer clusters surrounding by stroma in microengineered tumor stromal assay. We visualized a codynamic reduction in both cancer and stromal cells with bromodomain and extraterminal treatment compared to the dimethyl sulfoxide-treated group. This study demonstrates the ability to engineer tumor-stromal assays with patient-derived cells, study the role of diverse types of stromal cells on cancer progression, and precisely visualize a coculture during the screening of therapeutic compounds.

Artificial T Cell Mimetics to Combat Melanoma Tumor Growth.

Despite recent breakthroughs in melanoma treatment with anti-PD-1 immunotherapy, innovative approaches are needed to improve off-target effects. In this study, we report a T cell mimetic microparticle delivery of soluble PD1 aiming at providing a carrier substrate for future combinatorial and targeting efforts. Microparticles of sizes varying from (5 µm to-7 µm) were conjugated with soluble mouse or human PD-1 through nearly irreversible binding between streptavidin and biotin. PD-1 conjugated microparticles (PDMPs) suppressed 3-dimensional tumor growth of human A375 and mouse B16-F10 melanoma cells compared to control microparticles conjugated with the Fc portion of human IgG1 (IgG1MPs). This can be attributed to competitive inhibition by PDMPs on a melanoma cell-intrinsic PD-1/PD-L1 pathway. A single, local administration of mPDMPs in a B16-F10 mouse melanoma model inhibited tumor growth significantly compared to control IgMPs at the same dose. CD45+ immune cells were found to infiltrate tumors treated with mPDMPs as a mechanism for tumor control. These results collectively suggest that PDMPs can target the melanoma cell-intrinsic PD-1/PD-L1 pathway and that these artificial T cell mimetics can be the scaffold for further improvements in anti-tumor immunotherapy.

Therapeutic Delivery Specifications Identified Through Compartmental Analysis of a Mesenchymal Stromal Cell-Immune Reaction.

Despite widespread preclinical success, mesenchymal stromal cell (MSC) therapy has not reached consistent pivotal clinical endpoints in primary indications of autoinflammatory diseases. Numerous studies aim to uncover specific mechanisms of action towards better control of therapy using in vitro immunomodulation assays. However, many of these immunomodulation assays are imperfectly designed to accurately recapitulate microenvironment conditions where MSCs act. To increase our understanding of MSC efficacy, we herein conduct a systems level microenvironment approach to define compartmental features that can influence the delivery of MSCs' immunomodulatory effect in vitro in a more quantitative manner than ever before. Using this approach, we notably uncover an improved MSC quantification method with predictive cross-study applicability and unveil the key importance of system volume, time exposure to MSCs, and cross-communication between MSC and T cell populations to realize full therapeutic effect. The application of these compartmental analysis can improve our understanding of MSC mechanism(s) of action and further lead to administration methods that deliver MSCs within a compartment for predictable potency.

Stromalized microreactor supports murine hematopoietic progenitor enrichment.

There is an emerging need to process, expand, and even genetically engineer hematopoietic stem and progenitor cells (HSPCs) prior to administration for blood reconstitution therapy. A closed-system and automated solution for ex vivo HSC processing can improve adoption and standardize processing techniques. Here, we report a recirculating flow bioreactor where HSCs are stabilized and enriched for short-term processing by indirect fibroblast feeder coculture. Mouse 3 T3 fibroblasts were seeded on the extraluminal membrane surface of a hollow fiber micro-bioreactor and were found to support HSPC cell number compared to unsupported BMCs. CFSE analysis indicates that 3 T3-support was essential for the enhanced intrinsic cell cycling of HSPCs. This enhanced support was specific to the HSPC population with little to no effect seen with the Lineagepositive and Lineagenegative cells. Together, these data suggest that stromal-seeded hollow fiber micro-reactors represent a platform to screening various conditions that support the expansion and bioprocessing of HSPCs ex vivo.

Orthogonal potency analysis of mesenchymal stromal cell function during ex vivo expansion.

Adult bone marrow mesenchymal stromal cells (MSCs) have cross-functional, intrinsic potency that is of therapeutic interest. Their ability to regenerate bone, fat, and cartilage, modulate the immune system, and nurture the growth and function of other bone marrow hematopoietic stem/progenitor cells have all been evaluated by transplant applications of MSCs. These applications require the isolation and expansion scaled cell production. To investigate biophysical properties of MSCs that can be feasibly utilized as predictors of bioactivity during biomanufacturing, we used a low-density seeding model to drive MSCs into proliferative stress and exhibit the hallmark characteristics of in vitro aging. A low-density seeding method was used to generate MSCs from passages 1-7 to simulate serial expansion of these cells to maximize yield from a single donor. MSCs were subjected to three bioactivity assays in parallel to ascertain whether patterns in MSC age, size, and shape were associated with the outcomes of the potency assays. MSC age was found to be a predictor of adipogenesis, while cell and nuclear shape was strongly associated to hematopoietic-supportive potency. Together, these data evaluate morphological changes associated with cell potency and highlight new strategies for purification or alternatives to assessing MSC quality.

An engineered biomarker system to monitor and modulate immune clearance of cell therapies.

BACKGROUND AIMS: Cell transplants offer a new opportunity to deliver therapies with novel and complex mechanisms of action. Understanding the pharmacology of cell transplants is important to deliver this new therapy effectively. Currently, however, there are limited techniques to easily track cells after intravenous administration due to the dispersion of the graft throughout the entire body. METHODS: We herein developed an engineered cell system that secretes a luciferase enzyme to sensitively detect cell transplants independent of their locale by a simple blood test. We specifically studied a unique feature of cell transplant pharmacology-namely, immune clearance-using mesenchymal stromal cells (MSCs) as a proof-of-concept cell therapy. MSCs are a clinically relevant cell therapy that has been explored in several disease indications due to their innate properties of altering an immune response. RESULTS: Using this engineered reporter, we observed specific sensitivity of cell therapy exposure to the preparation of cells, cytolysis of MSCs in an allogeneic setting and a NK cell-mediated destruction of MSCs in an autologous setting. CONCLUSIONS: Our cellular tracking method has broader implications at large for assessing in vivo kinetics of various other cell therapies.

Intact soluble P-glycoprotein is secreted by sinonasal epithelial cells.

BACKGROUND: P-glycoprotein (P-gp) is a 170 kDa transmembrane efflux pump, which is upregulated in chronic rhinosinusitis. Studies of leukemia demonstrated that P-gp may also be secreted in an intact soluble form. The purpose of this study was to explore whether sinonasal epithelial cells were capable of secreting soluble P-gp and whether P-gp has any functional role. METHODS: Soluble and cytoplasmic P-gp were quantified in vehicle and lipopolysaccharide exposed cultures by enzyme-linked immunosorbent assay. The molecular weight of the soluble P-gp was determined by Western blot. Naive cultures were exposed to recombinant human P-gp at 0-2000 ng/mL. The degree of membranous interpolation was determined by quantitative fluorescent immunocytochemistry and function was determined by a calcein acetoxymethyl ester assay. RESULTS: Soluble P-gp was secreted intact at 170 kDa. Mean (standard deviation) secretion was detected within vehicle wells at 55.43 ± 26.26 ng/mL, which significantly increased to 333.27 ± 305.98 ng/mL (p < 0.001) after lipopolysaccharide stimulation. Soluble P-gp strongly and significantly correlated with cytoplasmic P-gp (r = 0.57, p = 0.000001). Exposure to 2000 ng/mL of recombinant P-gp significantly increased corrected total cell fluorescence (1.34 ± 1.85) relative to vehicle control 0.29 ± 0.26 (p = 0.01) and significantly reduced calcein acetoxymethyl ester fluorescence (82.03 ± 43.69) relative to 100 ng/mL recombinant P-gp exposed cells (123.11 ± 42.16, p = 0.001). CONCLUSION: Cultured sinonasal epithelial cells were able to both secrete intact P-gp and could functionally interpolate soluble P-gp into their cell membrane. These in vitro findings indicated that soluble P-gp may be present in nasal mucus as a biomarker and could participate in the maintenance of P-gp overexpression in chronic rhinosinusitis and associated inflammation.

P-glycoprotein regulates Staphylococcus aureus enterotoxin B-stimulated interleukin-5 and thymic stromal lymphopoietin secretion in organotypic mucosal explants.

BACKGROUND: T-helper 2 (Th2) inflammation is a hallmark of chronic rhinosinusitis with nasal polyps (CRSwNP) although the pathogenesis is poorly understood. P-glycoprotein (permeability glycoprotein, P-gp) is an efflux pump that is capable of regulating cytokine transport and is expressed within sinonasal mucosa. The purpose of this study was to examine if the oversecretion of interleukin 5 (IL-5) and thymic stromal lymphopoietin (TSLP) in CRSwNP could be explained through P-gp-mediated secretory pathways. METHODS: Fifteen ethmoid mucosal explants were harvested from patients with CRS (n = 10) and CRSwNP (n = 10) and stimulated with Staphylococcus aureus enterotoxin B (SEB). P-gp was inhibited using zosuquidar trihydrochloride (herein Zosuquidar). P-gp expression was measured using real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). IL-5, IL-8, and TSLP secretion were quantified using ELISA. RESULTS: P-gp protein was overexpressed in CRSwNP (28.32 ± 25.94 ng/mL per mg explant) as compared to CRS (10.74 ± 8.61; p = 0.01, 2-tailed Mann-Whitney U test). There was no difference in messenger RNA (mRNA) expression. SEB induced a significant increase in IL-5 and TSLP but not IL-8 secretion relative to control in the CRSwNP explants only. Subsequent P-gp inhibition significantly reduced IL-5 and TSLP secretion (p = 0.04 for both, 2-tailed Student t test) to control levels. The concentration of IL-5 and TSLP secretion were strongly and significantly correlated to the concentration of P-gp within the same explant (IL-5: r = 0.791, p = 0.001; TSLP: r = 0.687, p = 0.003; 2-tailed Spearman's rank-order correlation). CONCLUSION: P-gp protein is expressed at higher concentrations in CRSwNP as compared to CRS. This overexpression directly contributes to the relative hypersecretion of IL-5 and TSLP. These findings suggest a novel mechanism for Th2 skewing in CRSwNP.

Itraconazole and clarithromycin inhibit P-glycoprotein activity in primary human sinonasal epithelial cells.

BACKGROUND: Itraconazole and clarithromycin are clinically effective in the treatment of chronic rhinosinusitis (CRS) through incompletely understood anti-inflammatory properties. P-glycoprotein (P-gp) is overexpressed in CRS and inhibition results in decreased inflammatory cytokine secretion. Both itraconazole and clarithromycin have also been shown to have P-gp inhibitory properties in other tissues, suggesting a novel explanation for their immunomodulatory effects in CRS. The purpose of this study is to therefore confirm whether these drugs are capable of inhibiting P-gp specifically in sinonasal epithelial cells. METHODS: This was an institutional review board (IRB)-approved study in which primary sinonasal epithelial cells were cultured in 96-well plates. A Calcein AM assay was used to quantify P-gp inhibition as determined by an increase in intracellular fluorescence. A dose-response curve was generated for itraconazole and clarithromycin (maximal concentration 100 µM) and compared to that of Zosuquidar, a highly specific known P-gp inhibitor. Results were compared using a Student t test with a significance defined as p < 0.05. RESULTS: Both itraconazole and clarithromycin demonstrated a dose-response curve for P-gp inhibition similar to that of Zosuquidar. The respective maximal inhibitory concentrations of Zosuquidar, itraconazole, and clarithromycin prior to induction of cytotoxicity were 0.31, 3.13, and 1.56 µM, respectively, as demonstrated by a statistically significant increase in total intracellular fluorescence (p < 0.05 in all groups). CONCLUSION: Both itraconazole and clarithromycin are capable of inhibiting sinonasal epithelial cell associated P-gp. The anti-inflammatory effects of these agents in CRS may be attributable, in part, to their heretofore unrecognized P-gp modulatory properties.

Verapamil modulates interleukin-5 and interleukin-6 secretion in organotypic human sinonasal polyp explants.

BACKGROUND: Verapamil is an L-type calcium channel blocker (CCB) that has been shown to have immunomodulatory properties in a variety of tissues. The goal of this study was determine whether verapamil is capable of regulating cytokine secretion in sinonasal polyps and to compare this effect to dexamethasone, an established immunosuppressive corticosteroid. METHODS: This was an institutional review board (IRB)-approved study in sinonasal polyp explants derived from 8 patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Polyps were incubated with dexamethasone or verapamil for 24 hours followed by an additional 24 hours with Staphylococcal enterotoxin B (SEB). Concentrations of secreted cytokines over each exposure period were determined by enzyme-linked immunosorbent assay (ELISA) and are expressed as a percent. Results were compared using a 2-tailed Student t test. RESULTS: The percent of SEB-stimulated interleukin-5 (IL-5) secretion (mean ± standard deviation [SD], 339.94% ± 315.48%) between the second and first treatment periods was significantly reduced following exposure to dexamethasone (74.08% ± 26.77%, p < 0.05) and verapamil (119.99% ± 69.32%, p < 0.05). The percent of SEB-stimulated IL-6 secretion (217.53% ± 89.51%) was also significantly reduced following exposure to verapamil (148.82% ± 79.15%, p < 0.05) but not dexamethasone (148.86% ± 145.24%). Finally, the percent of SEB-stimulated thymic stromal lymphopoietin (TSLP) secretion (37.86% ± 18.88%) demonstrated a nonsignificant trend toward reduction with both dexamethasone (31.15% ± 35.28%) and verapamil (20.14% ± 12.10%). CONCLUSION: Although the mechanism has yet to be fully understood, L-type CCBs are capable of reducing inflammation in multiple tissues. Verapamil was specifically found to reduce airway goblet cell hyperplasia and eosinophilic infiltration in a murine asthma model. Our data support these findings suggesting that verapamil can modulate T-helper cell type 2 (Th2)-associated cytokine secretion in sinonasal polyp explants. This data points to a possible therapeutic role for CCBs in the management of CRSwNP.

P-glycoprotein inhibition promotes prednisone retention in human sinonasal polyp explants.

BACKGROUND: P-glycoprotein (P-gp) is an efflux pump, which is part of the innate chemo-immunity defense system and is overexpressed in chronic rhinosinusitis with nasal polyps (CRSwNP). P-gp is capable of regulating corticosteroid retention and thus P-gp upregulation has been implicated in steroid resistance in several inflammatory disorders. The goal of this study is to determine whether P-gp regulates intracellular steroid retention in CRSwNP. METHODS: This was a Massachusetts Eye and Ear Infirmary Institutional Review Board (IRB)-approved study in nasal polyp explants. Polyps were exposed to 50 µg/mL of prednisone for 30 minutes with or without the presence of a P-gp inhibitor (Verapamil 12.5 µM or Zosuquidar 0.31 µM) followed by a 40-minute washout period (n = 16 per group). Intracellular steroid retention was determined by quantifying the concentration of both intracytoplasmic and secreted steroid using an enzyme-linked immunosorbent assay (ELISA). Concentrations relative to control were compared using a Student t test. RESULTS: The intracytoplasmic prednisone concentration was significantly greater relative to control following P-gp inhibition with Verapamil (155.28% ± 22.48%, p < 0.05) and Zosuquidar (125.81% ± 12.41%, p < 0.05). Similarly, the amount of prednisone secreted by the explant was significantly reduced at 30 minutes following P-gp inhibition with Zosuquidar (78.64% ± 2.98%, p < 0.05) and 40 minutes following P-gp inhibition with Verapamil (80.56% ± 5.02%, p < 0.05). CONCLUSION: Inhibition of P-gp enhances the intracellular accumulation of prednisone in nasal polyps. This suggests that P-gp participates in regulation of glucocorticoid retention in sinonasal mucosa. These findings, coupled with the known overexpression of P-gp in CRSwNP, may point to a possible mechanism for steroid resistance in this patient population.