The adhesion receptor GPR56 is activated by extracellular matrix collagen III to improve ß-cell function.

AIMS: G-protein coupled receptor 56 (GPR56) is the most abundant islet-expressed G-protein coupled receptor, suggesting a potential role in islet function. This study evaluated islet expression of GPR56 and its endogenous ligand collagen III, and their effects on ß-cell function. METHODS: GPR56 and collagen III expression in mouse and human pancreas sections was determined by fluorescence immunohistochemistry. Effects of collagen III on ß-cell proliferation, apoptosis, intracellular calcium ([Ca2+]i) and insulin secretion were determined by cellular BrdU incorporation, caspase 3/7 activities, microfluorimetry and radioimmunoassay, respectively. The role of GPR56 in islet vascularisation and innervation was evaluated by immunohistochemical staining for CD31 and TUJ1, respectively, in pancreases from wildtype (WT) and Gpr56-/- mice, and the requirement of GPR56 for normal glucose homeostasis was determined by glucose tolerance tests in WT and Gpr56-/- mice. RESULTS: Immunostaining of mouse and human pancreases revealed that GPR56 was expressed by islet ß-cells while collagen III was confined to the peri-islet basement membrane and islet capillaries. Collagen III protected ß-cells from cytokine-induced apoptosis, triggered increases in [Ca2+]i and potentiated glucose-induced insulin secretion from WT islets but not from Gpr56-/- islets. Deletion of GPR56 did not affect glucose-induced insulin secretion in vitro and it did not impair glucose tolerance in adult mice. GPR56 was not required for normal islet vascularisation or innervation. CONCLUSION: We have demonstrated that collagen III improves islet function by increasing insulin secretion and protecting against apoptosis. Our data suggest that collagen III may be effective in optimising islet function to improve islet transplantation outcomes, and GPR56 may be a target for the treatment of type 2 diabetes.

The diet-derived short chain fatty acid propionate improves beta-cell function in humans and stimulates insulin secretion from human islets in vitro.

AIMS: Diet-derived short chain fatty acids (SCFAs) improve glucose homeostasis in vivo, but the role of individual SCFAs and their mechanisms of action have not been defined. This study evaluated the effects of increasing colonic delivery of the SCFA propionate on ß-cell function in humans and the direct effects of propionate on isolated human islets in vitro. MATERIALS AND METHODS: For 24 weeks human subjects ingested an inulin-propionate ester that delivers propionate to the colon. Acute insulin, GLP-1 and non-esterified fatty acid (NEFA) levels were quantified pre- and post-supplementation in response to a mixed meal test. Expression of the SCFA receptor FFAR2 in human islets was determined by western blotting and immunohistochemistry. Dynamic insulin secretion from perifused human islets was quantified by radioimmunoassay and islet apoptosis was determined by quantification of caspase 3/7 activities. RESULTS: Colonic propionate delivery in vivo was associated with improved ß-cell function with increased insulin secretion that was independent of changes in GLP-1 levels. Human islet ß-cells expressed FFAR2 and propionate potentiated dynamic glucose-stimulated insulin secretion in vitro, an effect that was dependent on signalling via protein kinase C. Propionate also protected human islets from apoptosis induced by the NEFA sodium palmitate and inflammatory cytokines. CONCLUSIONS: Our results indicate that propionate has beneficial effects on ß-cell function in vivo, and in vitro analyses demonstrated that it has direct effects to potentiate glucose-stimulated insulin release and maintain ß-cell mass through inhibition of apoptosis. These observations support ingestion of propiogenic dietary fibres to maintain healthy glucose homeostasis.

Splenic rupture after colorectal cancer screening.

The number of colonoscopies performed in recent years is increasing dramatically, specially those related to colorectal cancer screening programmes. For this reason, there is a direct relationship with the number of exceptional complications such as splenic rupture. We describe a clinical case of a splenic rupture with hemodynamic instability. Consequently, an emergency splenectomy was performed 6 hours after the colonoscopy was finished. Health staff should be aware of its existence, as an early reaction will avoid more severe problems.

Histiocitosis sinusal con linfadenopatía masiva en el hueso cuneiforme medial: reporte de un caso / Sinus histiocytosis with massive lymphadenopathy in the medial cuneiform bone: A case report

Introducción: la histiocitosis sinusal con linfadenopatía masiva (HSLM) es un trastorno histiocítico benigno que afecta con mayor frecuencia a adultos jóvenes. La afectación ósea es poco frecuente y se suele presentar en huesos largos. Presentación del caso: hombre de 38 años con diagnóstico de HSLM según biopsia de nódulo cutáneo. Seis meses después del diagnóstico, presentó dolor mecánico en el pie derecho, por lo que asistió a una nueva consulta. Se realizó exploración física y radiografía simple, encontrando una lesión lítica en el hueso cuneiforme medial que posteriormente fue confirmada con tomografía computarizada y resonancia magnética nuclear. Por lo anterior, se realizó la resección de la lesión lítica, curetaje y relleno con cemento de fosfato de calcio HydraSet (Stryker®). Se realizaron pruebas inmunohistoquímicas y estudio anatomopatológico en el tejido resecado, evidenciando tinción de proteínas CD68 y S100 positivas, y tinción de proteina CD1a negativa, así como proliferación histiocitaria. Un año después de la cirugía, el paciente se encontraba asintomático y realizaba actividades sin ninguna restricción.Conclusiones: esta enfermedad es poco frecuente; no obstante, debe considerarse en el diagnóstico diferencial de lesiones líticas en huesos, especialmente cuando hay lesiones en otras partes del cuerpo

Introduction: Sinus histiocytosis with massive lymphadenopathy (SHML), also known as Rosai-Dorfman disease, is a benign histiocytic disorder most commonly found in young adults. Bone involvement is rare and usually occurs in long bones.Case presentation: 38-year-old man diagnosed with SHML based on skin lesion biopsy. Six months after diagnosis, he presented with mechanical pain in the right foot, so he attended a new medical appointment. Physical examination and a non-enhanced X-ray were performed, finding a lytic lesion in the medial cuneiform bone, which was later confirmed with computed tomography and nuclear magnetic resonance imaging. The lytic lesion was excised, curetted and filled with calcium phosphate cement HydraSet (Stryker®). Immunohistochemical tests and anatomopathological study were performed on the excised tissue, evidencing positive CD68 and S100 protein staining and negative CD1a protein staining, as well as histiocyte proliferation. One year after surgery, the patient was asymptomatic and performed activities without any restriction.Conclusions: Even though HSLM is a rare disease, it should be considered in the differential diagnosis of lytic lesions in the bones, especially when there are lesions in other parts of the body

Fine tuning of insulin secretion by release of nerve growth factor from mouse and human islet ß-cells.

Nerve growth factor (NGF) is a protein required for neuronal development that also has regulatory functions in non-neuronal cells. Both NGF and its membrane receptors trkA and p75(NTR) are expressed by islet ß-cells. In this study we dynamically profiled NGF secretion from islets and used selective trkA and p75(NTR) inhibitors to identify the role of endogenous NGF in ß-cell stimulus-secretion coupling. NGF secretion from mouse islets was transient and did not accompany the sustained second phase of glucose-induced insulin secretion. Despite being present in human islets, NGF was not released at sufficient levels to be quantified. Inhibition of NGF signaling through trkA and p75(NTR) increased basal insulin secretion from both human and mouse islets, but impaired glucose-stimulated insulin secretion. These data support a role for islet NGF in fine-tuning insulin secretion, to both maintain a low basal level of insulin output and contribute to the biphasic secretory response to glucose.

Rotura esplénica tras colonoscopia de cribado de cáncer colorrectal / Splenic rupture after colorectal cancer screening

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Apendicitis de muñón. ¿Una realidad infravalorada? / Stump appendicitis. Underrated reality?

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