Adjuvant conditioning induces an immunosuppressive milieu that delays alloislet rejection through the expansion of myeloid-derived suppressor cells.

Advances in immunosuppression have been relatively stagnant over the past 2 decades, and transplant recipients continue to experience long-term morbidity associated with immunosuppression regimens. Strategies to reduce or eliminate the dosage of immunosuppression medications are needed. We discovered a novel administration strategy using the classic adjuvant alum to condition murine islet transplant recipients, known as adjuvant conditioning (AC), to expand both polymorphonuclear and monocytic myeloid-derived suppressive cells (MDSCs) in vivo. These AC MDSCs potently suppress T cell proliferation when cultured together in vitro. AC MDSCs also facilitate naïve CD4+ T cells to differentiate into regulatory T cells. In addition, we were able to demonstrate a significant delay in alloislet rejection compared with that by saline-treated control following adjuvant treatment in a MDSC-dependent manner. Furthermore, AC MDSCs produce significantly more interleukin (IL)-10 than saline-treated controls, which we demonstrated to be critical for the increased T cell suppressor function of AC MDSCs as well as the observed protective effect of AC against alloislet rejection. Our data suggest that adjuvant-related therapeutics designed to expand MDSCs could be a useful strategy to prevent transplant rejection and curb the use of toxic immunosuppressive regimens currently used in transplant patients.

Bone Marrow Stem Cells Derived from Nerves Have Neurogenic Properties and Potential Utility for Regenerative Therapy.

Neurons and glia of the peripheral nervous system are derived from progenitor cell populations, originating from embryonic neural crest. The neural crest and vasculature are intimately associated during embryonic development and in the mature central nervous system, in which they form a neurovascular unit comprised of neurons, glia, pericytes, and vascular endothelial cells that play important roles in health and disease. Our group and others have previously reported that postnatal populations of stem cells originating from glia or Schwann cells possess neural stem cell qualities, including rapid proliferation and differentiation into mature glia and neurons. Bone marrow receives sensory and sympathetic innervation from the peripheral nervous system and is known to contain myelinating and unmyelinating Schwann cells. Herein, we describe a population of neural crest-derived Schwann cells residing in a neurovascular niche of bone marrow in association with nerve fibers. These Schwann cells can be isolated and expanded. They demonstrate plasticity in vitro, generating neural stem cells that exhibit neurogenic potential and form neural networks within the enteric nervous system in vivo following transplantation to the intestine. These cells represent a novel source of autologous neural stem cells for the treatment of neurointestinal disorders.

Triple gallbladder with heterotopic gastric mucosa: a case report.

BACKGROUND: Triple gallbladder is a rare congenital anomaly of the biliary tract that can be associated with heterotopic tissue. Gallbladder triplication results from the failure of rudimentary bile ducts to regress during embryological development, and can be difficult to distinguish from Todani type II choledochal cysts and biliary duplication cysts. CASE PRESENTATION: A 2-year-old patient presented to our institution with intermittent abdominal pain for 1 year. She had elevated transaminases with imaging concerning for a choledochal cyst. After assessment with magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography, she was diagnosed with a gallbladder multiplication and a common bile duct stricture. She underwent laparoscopic cholecystectomy, which confirmed the diagnosis of triple gallbladder. One of the three gallbladders demonstrated heterotopic gastric mucosa on final pathology, including at the cystic duct margin. Follow up testing with a technetium 99 m scan demonstrated a subtle focus of increased activity in the right upper abdomen at the expected location of the common bile duct, concerning for the presence of residual gastric mucosa. The patient remains well without abdominal pain. CONCLUSIONS: We describe the first case of heterotopic gastric mucosa in a triple gallbladder in a young patient presenting with chronic abdominal pain. We also demonstrate the safety and feasibility of laparoscopic cholecystectomy in young children with triple gallbladder. Finally, we propose an interdisciplinary approach to the management of common bile duct strictures in the setting of ectopic acid secretion, involving a combination of medical management, endoscopic intervention, and possible salvage laparoscopic Roux-en-Y hepaticojejunostomy.

c-MPL provides tumor-targeted T-cell receptor-transgenic T cells with costimulation and cytokine signals.

Adoptively transferred T-cell receptor (TCR)-engineered T cells depend on host-derived costimulation and cytokine signals for their full and sustained activation. However, in patients with cancer, both signals are frequently impaired. Hence, we developed a novel strategy that combines both essential signals in 1 transgene by expressing the nonlymphoid hematopoietic growth factor receptor c-MPL (myeloproliferative leukemia), the receptor for thrombopoietin (TPO), in T cells. c-MPL signaling activates pathways shared with conventional costimulatory and cytokine receptor signaling. Thus, we hypothesized that host-derived TPO, present in the tumor microenvironment, or pharmacological c-MPL agonists approved by the US Food and Drug Administration could deliver both signals to c-MPL-engineered TCR-transgenic T cells. We found that c-MPL+ polyclonal T cells expand and proliferate in response to TPO, and persist longer after adoptive transfer in immunodeficient human TPO-transgenic mice. In TCR-transgenic T cells, c-MPL activation enhances antitumor function, T-cell expansion, and cytokine production and preserves a central memory phenotype. c-MPL signaling also enables sequential tumor cell killing, enhances the formation of effective immune synapses, and improves antileukemic activity in vivo in a leukemia xenograft model. We identify the type 1 interferon pathway as a molecular mechanism by which c-MPL mediates immune stimulation in T cells. In conclusion, we present a novel immunotherapeutic strategy using c-MPL-enhanced transgenic T cells responding to either endogenously produced TPO (a microenvironment factor in hematologic malignancies) or c-MPL-targeted pharmacological agents.

Role of Noncanonical Wnt Signaling Pathway in Human Aortic Valve Calcification.

OBJECTIVE: The mechanisms underlying the pathogenesis of aortic valve calcification remain unclear. With accumulating evidence demonstrating that valve calcification recapitulates bone development, the crucial roles of noncanonical Wnt ligands WNT5a, WNT5b, and WNT11 in osteogenesis make them critical targets in the study of aortic valve calcification. APPROACH AND RESULTS: Using immunohistochemistry, real-time qPCR, Western blotting, and tissue culture, we examined the tissue distribution of WNT5a, WNT5b, and WNT11 in noncalcified and calcified aortic valves and their effects on human aortic valve interstitial cells (HAVICs). Only focal strong immunostaining for WNT5a was seen in and around areas of calcification. Abundant immunostaining for WNT5b and WNT11 was seen in inflammatory cells, fibrosis, and activated myofibroblasts in areas of calcified foci. There was significant correlation between WNT5b and WNT11 overall staining and presence of calcification, lipid score, fibrosis, and microvessels (P<0.05). Real-time qPCR and Western blotting revealed abundant expression of both Wnts in stenotic aortic valves, particularly in bicuspid valves. Incubation of HAVICs from noncalcified valves with the 3 noncanonical Wnts significantly increased cell apoptosis and calcification (P<0.05). Treatment of HAVICs with the mitogen-activated protein kinase-38ß and GSK3ß inhibitors significantly reduced their mineralization (P<0.01). Raman spectroscopy identified the inorganic phosphate deposits as hydroxyapatite and showed a significant increase in hydroxyapatite deposition in HAVICs in response to WNT5a and WNT11 (P<0.05). Similar crystallinity was seen in the deposits found in HAVICs treated with Wnts and in calcified human aortic valves. CONCLUSIONS: These findings suggest a potential role for noncanonical Wnt signaling in the pathogenesis of aortic valve calcification.

Optogenetic Activation of Cholinergic Enteric Neurons Reduces Inflammation in Experimental Colitis.

BACKGROUND & AIMS: Intestinal inflammation is associated with loss of enteric cholinergic neurons. Given the systemic anti-inflammatory role of cholinergic innervation, we hypothesized that enteric cholinergic neurons similarly possess anti-inflammatory properties and may represent a novel target to treat inflammatory bowel disease. METHODS: Mice were fed 2.5% dextran sodium sulfate (DSS) for 7 days to induce colitis. Cholinergic enteric neurons, which express choline acetyltransferase (ChAT), were focally ablated in the midcolon of ChAT::Cre;R26-iDTR mice by local injection of diphtheria toxin before colitis induction. Activation of enteric cholinergic neurons was achieved using ChAT::Cre;R26-ChR2 mice, in which ChAT+ neurons express channelrhodopsin-2, with daily blue light stimulation delivered via an intracolonic probe during the 7 days of DSS treatment. Colitis severity, ENS structure, and smooth muscle contractility were assessed by histology, immunohistochemistry, quantitative polymerase chain reaction, organ bath, and electromyography. In vitro studies assessed the anti-inflammatory role of enteric cholinergic neurons on cultured muscularis macrophages. RESULTS: Ablation of ChAT+ neurons in DSS-treated mice exacerbated colitis, as measured by weight loss, colon shortening, histologic inflammation, and CD45+ cell infiltration, and led to colonic dysmotility. Conversely, optogenetic activation of enteric cholinergic neurons improved colitis, preserved smooth muscle contractility, protected against loss of cholinergic neurons, and reduced proinflammatory cytokine production. Both acetylcholine and optogenetic cholinergic neuron activation in vitro reduced proinflammatory cytokine expression in lipopolysaccharide-stimulated muscularis macrophages. CONCLUSIONS: These findings show that enteric cholinergic neurons have an anti-inflammatory role in the colon and should be explored as a potential inflammatory bowel disease treatment.

Innate immune cellular therapeutics in transplantation.

Successful organ transplantation provides an opportunity to extend the lives of patients with end-stage organ failure. Selectively suppressing the donor-specific alloimmune response, however, remains challenging without the continuous use of non-specific immunosuppressive medications, which have multiple adverse effects including elevated risks of infection, chronic kidney injury, cardiovascular disease, and cancer. Efforts to promote allograft tolerance have focused on manipulating the adaptive immune response, but long-term allograft survival rates remain disappointing. In recent years, the innate immune system has become an attractive therapeutic target for the prevention and treatment of transplant organ rejection. Indeed, contemporary studies demonstrate that innate immune cells participate in both the initial alloimmune response and chronic allograft rejection and undergo non-permanent functional reprogramming in a phenomenon termed "trained immunity." Several types of innate immune cells are currently under investigation as potential therapeutics in transplantation, including myeloid-derived suppressor cells, dendritic cells, regulatory macrophages, natural killer cells, and innate lymphoid cells. In this review, we discuss the features and functions of these cell types, with a focus on their role in the alloimmune response. We examine their potential application as therapeutics to prevent or treat allograft rejection, as well as challenges in their clinical translation and future directions for investigation.

The Oxidative Stress and Nervous Distress Connection in Gastrointestinal Disorders.

Oxidative stress is increasingly recognized as a central player in a range of gastrointestinal (GI) disorders, as well as complications stemming from therapeutic interventions. This article presents an overview of the mechanisms of oxidative stress in GI conditions and highlights a link between oxidative insult and disruption to the enteric nervous system (ENS), which controls GI functions. The dysfunction of the ENS is characteristic of a spectrum of disorders, including neurointestinal diseases and conditions such as inflammatory bowel disease (IBD), diabetic gastroparesis, and chemotherapy-induced GI side effects. Neurons in the ENS, while essential for normal gut function, appear particularly vulnerable to oxidative damage. Mechanistically, oxidative stress in enteric neurons can result from intrinsic nitrosative injury, mitochondrial dysfunction, or inflammation-related pathways. Although antioxidant-based therapies have shown limited efficacy, recognizing the multifaceted role of oxidative stress in GI diseases offers a promising avenue for future interventions. This comprehensive review summarizes the literature to date implicating oxidative stress as a critical player in the pathophysiology of GI disorders, with a focus on its role in ENS injury and dysfunction, and highlights opportunities for the development of targeted therapeutics for these diseases.

Oxidative Stress and Neural Dysfunction in Gastrointestinal Diseases: Can Stem Cells Offer a Solution?

Oxidative stress is involved in many gastrointestinal (GI) disorders as either the primary pathogenesis (radiation, chemotherapy, toxicity, ischemia-reperfusion) or a secondary driving force of disease progression (inflammation and diabetes). The GI tract is innervated intrinsically by the enteric nervous system (ENS) with a diverse role in maintaining gut homeostasis and GI motility. Complications in the physiological functioning of the ENS results in GI dysfunction that can result in debilitating sequelae from dysmotility greatly impacting quality of life and leading to potentially fatal complications. Therapeutics to remedy either oxidative stress or enteric neuronal dysfunction are severely limited, resulting in a critical gap in clinical care for GI disease and neurointestinal complications. Stem cell therapies have shown great promise in the treatment of several gut disorders via mechanisms including cell regeneration, anti-inflammatory activity, providing trophic support, and emerging evidence of antioxidant and neuroprotective functions. The potential of mesenchymal stem cell (MSC) therapies and recent evidence of their antioxidant and neuroprotective activity in several GI conditions are discussed. Finally, future therapeutic aspects of stem cell-based tools for combatting oxidative stress and enteric neuropathies in GI disease are considered.

Organ allocation in pediatric abdominal transplant.

Pediatric patients constitute an important group within the general transplant population, given the opportunity to significantly extend their lives with successful transplantation. Children have historically received special consideration under the various abdominal solid organ allocation algorithms, but matching patients with size and weight restrictions with appropriate donors remains an ongoing issue. Here, we describe the historical trends in pediatric organ allocation policies for liver, kidney, intestine, and pancreas transplantation. We also review recent changes to these allocation policies, with particular attention to recent amendments to geographical prioritization, with the dissolution of donor service areas and United Network for Organ Sharing (UNOS) regions and the subsequent creation of acuity circles.

Best Study Strategy for the NBME Clinical Science Surgery Exam.

INTRODUCTION: Providing medical students with effective study strategies is paramount in fostering their success on the NBME Clinical Science Surgery exam. As of yet, there has not been a comprehensive inquiry into a study strategy for this exam. We aim to identify if the following are associated with higher NBME raw exam scores: (1) the use of popular study materials, (2) the number of study materials used, and (3) the amount of time spent studying throughout the clerkship. METHODS: Over the period of 1 academic year, third-year medical students at our institution were administered a survey during their surgical clerkship inquiring about study materials used and hours spent studying per week. The data were then matched to students' raw NBME scores and then depersonalized. A total of 82 of 193 (42%) students responded with an overall average raw score of 76.74 on the NBME Clinical Science Surgery exam. By comparing our data to the NBME national average of 70 with a standard deviation of 8, a z test was used to compare the population mean to our sample means. RESULTS: When investigating resources used, the combination of using an online question bank and a high yield review book yielded a high z score (6.23) and using 4 resources yielded the highest z score (6.28). Regarding study hours, the highest z scores were seen when students studied for 6 to 10 hours per week during the first half of the clerkship, and 11 to 15 hours per week during the second half of the clerkship (5.76 and 6.02, respectively). CONCLUSIONS: In conclusion, higher NBME Clinical Science Surgery exam scores were correlated with the use of multiple and varied types of resources and increasing study time closer to the exam date. The resources and methods utilized by students achieving the highest exam scores can be recommended by surgical educators and employed by other medical students to foster academic success.

Endovascular Management of Multiple Dysplastic Aneurysms in a Young Man with an Unknown Underlying Cause: A Case Report and Review of the Literature.

BACKGROUND: Intracranial aneurysms are the leading cause of nontraumatic subarachnoid hemorrhage and are most commonly associated with the anterior cerebral artery (ACA) and anterior communicating artery complex. We describe the presentation and management of a 27-year-old man with concurrent bilateral A1-2 junction aneurysms and fusiform intraorbital ophthalmic artery (OA) aneurysms. CASE DESCRIPTION: A 27-year-old man with no past medical history presented with 3 months of headaches. Imaging showed a large dysplastic left A1-2 junction aneurysm and a smaller saccular right A1-2 junction aneurysm, with potentially adherent domes. Two fusiform aneurysms of the intraorbital segment of the left OA were also identified. The patient underwent coil-assisted pipeline embolization of the left A1-A2 aneurysm, with complete obliteration and reconstitution of the normal parent vessel. The patient underwent coil embolization of the right A1-2 aneurysm 3 weeks later, which was found to have grown significantly at the time of treatment. Three-month follow-up showed spontaneous resolution of the OA aneurysms, persistent obliteration of the left aneurysm, and significant recurrence of the right aneurysm, which was treated with stent-assisted coil embolization. A second recurrence 3 months later was successfully treated with repeat coiling. At the time of this treatment, the patient was also found to have 2 de novo distal middle cerebral artery and ACA dysplastic aneurysms, which were not treated. Follow-up angiography 6 weeks later showed stable complete obliteration of the right A1-2 aneurysm and interval complete resolution of the dysplastic middle cerebral artery aneurysm. The distal ACA aneurysm was observed to have minimally increased in size; however, the parent vessel showed signs of interval partial thrombosis with contrast stasis within the aneurysm. This final aneurysm is being followed with serial imaging. The patient remains neurologically intact with complete resolution of his headaches. CONCLUSIONS: We report the case of a young man with no past medical history who presented with multiple dysplastic aneurysms. Successful staged endovascular intervention resulted in obliteration of aneurysms with spontaneous obliteration of the intraorbital OA aneurysms observed at 3 months. We present this case to review the multiple challenges of managing complex ACA aneurysms and to highlight the usefulness of endovascular intervention in their treatment.

Lipoprotein(a) Induces Human Aortic Valve Interstitial Cell Calcification.

Lipoprotein(a), or Lp(a), significantly increased alkaline phosphatase activity, release of phosphate, calcium deposition, hydroxyapatite, cell apoptosis, matrix vesicle formation, and phosphorylation of signal transduction proteins; increased expression of chondro-osteogenic mediators; and decreased SOX9 and matrix Gla protein (p < 0.001). Inhibition of MAPK38 and GSK3ß significantly reduced Lp(a)-induced calcification of human aortic valve interstitial cells (p < 0.001). There was abundant presence of Lp(a) and E06 immunoreactivity in diseased human aortic valves. The present study demonstrates a causal effect for Lp(a) in aortic valve calcification and suggests that interfering with the Lp(a)pathway could provide a novel therapeutic approach in the management of this debilitating disease.