RESUMO
Treatment of multiple myeloma (MM) is complex; however, with equal access to care, clinical outcomes for Black patients match those in other patient groups. To reveal and begin to address clinical practice barriers to equitable, patient-centered MM care, this quality improvement (QI) initiative assessed patient electronic medical records (EMRs) and surveyed patients and providers at two large hospital systems and four community-based practices. For the educational intervention, providers participated in feedback-focused grand rounds sessions to reflect on system barriers and develop action plans to improve MM care. EMR reviews revealed infrequent documentation of cytogenetics and disease staging at community-based practices compared to large hospital systems. In surveys, providers from each care setting reported different challenges in MM care. Notably, the goals of treatment for patients and providers aligned at community clinics while providers and patients from large hospital systems had discordant perspectives. However, providers in community settings underreported race-associated barriers to care and identified different factors impacting treatment decision-making than Black patients. Relative to pre-session responses, providers were more likely to report high confidence after the educational sessions in aligning treatment decisions with guidelines and clinical evidence and shared decision-making (SDM). This QI study identified discordant perceptions among providers at large hospital systems and community-based practices in providing quality MM care. Provider education yielded increased confidence in and commitment to patient-centered care.
Assuntos
Mieloma Múltiplo , Melhoria de Qualidade , Humanos , Assistência Centrada no Paciente , Pacientes , Serviços de Saúde ComunitáriaRESUMO
State Medical Boards (SMBs) can take severe disciplinary actions (e.g., license revocation or suspension) against physicians who commit egregious wrongdoing in order to protect the public. However, there is noteworthy variability in the extent to which SMBs impose severe disciplinary action. In this manuscript, we present and synthesize a subset of 11 recommendations based on findings from our team's larger consensus-building project that identified a list of 56 policies and legal provisions SMBs can use to better protect patients from egregious wrongdoing by physicians.
Assuntos
Médicos , Má Conduta Profissional , Humanos , Licenciamento em MedicinaRESUMO
Although current implementations of super-resolution microscopy are technically approaching true molecular-scale resolution, this has not translated to imaging of biological specimens, because of the large size of conventional affinity reagents. Here we introduce slow off-rate modified aptamers (SOMAmers) as small and specific labeling reagents for use with DNA points accumulation in nanoscale topography (DNA-PAINT). To demonstrate the achievable resolution, specificity, and multiplexing capability of SOMAmers, we labeled and imaged both transmembrane and intracellular targets in fixed and live cells.
Assuntos
Aptâmeros de Nucleotídeos/química , Proteínas de Fluorescência Verde/química , Limite de Detecção , Microscopia de Fluorescência/métodosRESUMO
The nucleobases comprising DNA and RNA aptamers provide considerably less chemical diversity than protein-based ligands, limiting their versatility. The introduction of novel functional groups at just one of the four bases in modified aptamers has recently led to dramatic improvement in the success rate of identifying nucleic acid ligands to protein targets. Here we explore the benefits of additional enhancement in physicochemical diversity by selecting modified DNA aptamers that contain amino-acid-like modifications on both pyrimidine bases. Using proprotein convertase subtilisin/kexin type 9 as a representative protein target, we identify specific pairwise combinations of modifications that result in higher affinity, metabolic stability, and inhibitory potency compared with aptamers with single modifications. Such doubly modified aptamers are also more likely to be encoded in shorter sequences and occupy nonoverlapping epitopes more frequently than aptamers with single modifications. These highly modified DNA aptamers have broad utility in research, diagnostic, and therapeutic applications.
Assuntos
Aptâmeros de Nucleotídeos , Técnica de Seleção de Aptâmeros , Linhagem Celular Tumoral , Desoxirribonucleases/metabolismo , Biblioteca Gênica , Humanos , Ligantes , Inibidores de PCSK9 , Pró-Proteína Convertase 9/química , Pró-Proteína Convertase 9/genéticaRESUMO
RATIONALE: National quality improvement initiatives emphasize building partnerships between patients and providers by promoting patient engagement through communication, shared decision-making, and self-care skills. Efforts to promote patient engagement are especially important for people with asthma. To cultivate effective partnerships in asthma care, patients and providers may benefit from understanding each other's values and perceptions regarding treatment goals, shared decision-making, as well as barriers to optimal care and outcomes. OBJECTIVES: We conducted a survey study to assess and compare asthma patient and provider perceptions of factors that are associated with effective partnerships and patient engagement. METHODS: Surveys were administered to adult patients with poorly controlled asthma (n = 328) and their physicians (n = 40) before they participated in collaborative learning sessions held in 40 allergy and immunology practices across the United States. The surveys included items for both groups to report their asthma-related treatment goals and perceptions about information needs and knowledge, shared decision-making, and barriers to medication adherence. RESULTS: Providers rated their knowledge about different aspects of their patients' health status (on a scale from 1 = poor knowledge to 5 = excellent knowledge). The lowest percentages of ratings 4 and 5 were for knowledge about patients' financial status (29%), adherence (42%), lifestyle (46%), and workplace situation (46%). The highest percentages of ratings 4 and 5 were for knowledge about patients' exacerbation history (75%), smoking status (76%), hospitalization history (79%), and comorbidities (79%). The percentages of patients and providers, respectively, who indicated the following treatment goals as important differed significantly: preventing exacerbations (62% and 83%; P = 0.01), preventing emergency department visits (44% and 76%; P < 0.01), and improving ability to perform daily activities (69% and 48%; P < 0.01). However, there were no significant differences in percentages of provider-reported goals and goals that providers estimated their patients would indicate as important. Disconnects were also observed for perceived barriers to asthma medication adherence. CONCLUSIONS: The observed disconnects in patient and provider perceptions may inform strategies for cultivating effective partnerships and patient engagement to improve care quality and outcomes for people with asthma.
Assuntos
Asma/tratamento farmacológico , Tomada de Decisões , Adesão à Medicação/estatística & dados numéricos , Participação do Paciente , Assistência Centrada no Paciente/normas , Atitude do Pessoal de Saúde , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Avaliação das Necessidades , Melhoria de Qualidade , Autocuidado , Inquéritos e Questionários , Estados UnidosRESUMO
BACKGROUND: Low rates of compliance with quality measures for inflammatory bowel disease (IBD) have been reported for US gastroenterologists. AIMS: We assessed the influence of quality improvement (QI) education on compliance with physician quality reporting system (PQRS) measures for IBD and measures related to National Quality Strategy (NQS) priorities. METHODS: Forty community-based gastroenterologists participated in the QI study; 20 were assigned to educational intervention and control groups, respectively. At baseline, randomly selected charts of patients with moderate-to-severe ulcerative colitis were retrospectively reviewed for the gastroenterologists' performance of 8 PQRS IBD measures and 4 NQS-related measures. The intervention group participated in a series of accredited continuing medical education (CME) activities focusing on QI. Follow-up chart reviews were conducted 6 months after the CME activities. Independent t tests were conducted to compare between-group differences in baseline-to-follow-up rates of documented compliance with each measure. RESULTS: The analysis included 299 baseline charts and 300 follow-up charts. The intervention group had significantly greater magnitudes of improvement than the control group for the following measures: assessment of IBD type, location, and activity (+14 %, p = 0.009); influenza vaccination (+13 %, p = 0.025); pneumococcal vaccination (+20 %, p = 0.003); testing for latent tuberculosis before anti-TNF-α therapy (+10 %, p = 0.028); assessment of hepatitis B virus status before anti-TNF-α therapy (+9 %, p = 0.010); assessment of side effects (+17 %, p = 0.048), and counseling patients about cancer risks (+13 %, p = 0.013). CONCLUSIONS: QI-focused CME improves community-based gastroenterologists' compliance with IBD quality measures and measures aligned with NQS priorities.
Assuntos
Educação Médica Continuada , Gastroenterologia/educação , Doenças Inflamatórias Intestinais/terapia , Auditoria Médica/estatística & dados numéricos , Melhoria de Qualidade/estatística & dados numéricos , Adulto , Feminino , Gastroenterologia/normas , Fidelidade a Diretrizes/estatística & dados numéricos , Humanos , Masculino , Estudos RetrospectivosRESUMO
The conformational landscape of HIV-1 protease (PR) can be experimentally characterized by pulsed-EPR double electron-electron resonance (DEER). For this characterization, nitroxide spin labels are attached to an engineered cysteine residue in the flap region of HIV-1 PR. DEER distance measurements from spin-labels contained within each flap of the homodimer provide a detailed description of the conformational sampling of apo-enzyme as well as induced conformational shifts as a function of inhibitor binding. The distance distribution profiles are further interpreted in terms of a conformational ensemble scheme that consists of four unique states termed "curled/tucked", "closed", "semi-open" and "wide-open" conformations. Reported here are the DEER results for a drug-resistant variant clinical isolate sequence, V6, in the presence of FDA approved protease inhibitors (PIs) as well as a non-hydrolyzable substrate mimic, CaP2. Results are interpreted in the context of the current understanding of the relationship between conformational sampling, drug resistance, and kinetic efficiency of HIV-1PR as derived from previous DEER and kinetic data for a series of HIV-1PR constructs that contain drug-pressure selected mutations or natural polymorphisms. Specifically, these collective results support the notion that inhibitor-induced closure of the flaps correlates with inhibitor efficiency and drug resistance. This body of work also suggests DEER as a tool for studying conformational sampling in flexible enzymes as it relates to function.
Assuntos
Espectroscopia de Ressonância de Spin Eletrônica , Protease de HIV/química , HIV-1/química , Sequência de Aminoácidos , Clonagem Molecular , Resistência a Medicamentos , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Protease de HIV/genética , HIV-1/efeitos dos fármacos , Humanos , Modelos Moleculares , Conformação ProteicaRESUMO
BACKGROUND: In recent years, leading organizations in inflammatory bowel disease (IBD) have developed quality measures for the care of adults with Crohn's disease or ulcerative colitis. We used chart audits to assess the impact of quality improvement educational activities on documented adherence to Physician Quality Reporting System measures for IBD. METHODS: Twenty community-based gastroenterologists were recruited to participate in baseline chart audits (n = 200), a series of 4 accredited educational activities with feedback, and follow-up chart audits (n = 200). Trained abstractors reviewed randomly selected charts of adults with moderate or severe Crohn's disease. The charts were retrospectively abstracted for physicians' documented performance of the 2013 Physician Quality Reporting System IBD quality measures. We compared the physicians' baseline and posteducation rates of documented adherence with 10 of these measures. In a secondary analysis, we compared preeducation with posteducation difference scores of low-performing physicians, those whose baseline documentation rates were in the lowest quartile, and the rest of the cohort. RESULTS: At baseline, documentation of mean provider-level adherence to the 10 quality measures ranged from 3% to 98% (grand mean = 35.8%). In the overall analysis, baseline and posteducation rates of documented adherence did not differ significantly for any of the measures. However, for 4 measures, preeducation to posteducation difference scores were significantly greater among low performers than physicians in the highest 3 quartiles. CONCLUSIONS: The results of this preliminary pragmatic study indicate that quality improvement education affords the potential to improve adherence to Physician Quality Reporting System quality measures for IBD among low-performing gastroenterologists.
Assuntos
Doença de Crohn , Gastroenterologia/normas , Fidelidade a Diretrizes/estatística & dados numéricos , Auditoria Médica/estatística & dados numéricos , Avaliação de Resultados da Assistência ao Paciente , Melhoria de Qualidade , Adulto , Idoso , Educação Médica Continuada/métodos , Educação Médica Continuada/estatística & dados numéricos , Feminino , Gastroenterologia/educação , Humanos , Masculino , Pessoa de Meia-Idade , Melhoria de Qualidade/estatística & dados numéricos , Estudos RetrospectivosRESUMO
Chemically-modified derivatives of cytidine, bearing a 5-(N-substituted-carboxamide) functional group, are new reagents for use in aptamer discovery via the SELEX process (Systematic Evolution of Ligands by EXponential enrichment). Herein, we disclose a practical synthesis of 5-(N-benzylcarboxamide)-2'-deoxycytidine, and the corresponding 5-(N-1-naphthylmethylcarboxamide)- and 5-(N-3-phenylpropylcarboxamide)-2'-deoxycytidine analogs, as both the suitably-protected 3'-O-cyanoethylphosphoramidite reagents (CEP; gram scale) and the 5'-O-triphosphate reagents (TPP; milligram-scale). The key step in the syntheses is a mild, palladium(0)-catalyzed carboxyamidation of an unprotected 5-iodo-cytidine. Use of the CEP reagents for solid-phase oligonucleotide synthesis was demonstrated and incorporation of the TPP reagents by KOD polymerase in a primer extension assay confirmed the utility of these reagents for SELEX. Finally, the carboxyamidation reaction was also used to prepare the nuclease-resistant sugar-variants: 5-(N-benzylcarboxamide)-2'-O-methyl-cytidine and 5-(N-3-phenylpropylcarboxamide)-2'-deoxy-2'-fluoro-cytidine.
Assuntos
Citidina/síntese química , Oligonucleotídeos/síntese química , Citidina/análogos & derivados , Citidina/química , Oligonucleotídeos/química , Técnicas de Síntese em Fase SólidaRESUMO
INTRODUCTION: In recent years researchers have reported deficits in the quality of care provided to patients with rheumatoid arthritis (RA), including low rates of performance on quality measures. We sought to determine the influence of a quality improvement (QI) continuing education program on rheumatologists' performance on national quality measures for RA, along with other measures aligned with National Quality Strategy priorities. Performance was assessed through baseline and post-education chart audits. METHODS: Twenty community-based rheumatologists across the United States were recruited to participate in the QI education program and chart audits. Charts were retrospectively audited before (n = 160 charts) and after (n = 160 charts) the rheumatologists participated in a series of accredited QI-focused educational activities that included private audit feedback, small-group webinars, and online- and mobile-accessible print and video activities. The charts were audited for patient demographics and the rheumatologists' documented performance on the 6 quality measures for RA included in the Physician Quality Reporting System (PQRS). In addition, charts were abstracted for documentation of patient counseling about medication benefits/risks and adherence, lifestyle modifications, and quality of life; assessment of RA medication side effects; and assessment of RA medication adherence. RESULTS: Mean rates of documented performance on 4 of the 6 PQRS measures for RA were significantly higher in the post-education versus baseline charts (absolute increases ranged from 9 to 24% of patient charts). In addition, after the intervention, significantly higher mean rates were observed for patient counseling about medications and quality of life, and for assessments of medication side effects and adherence (absolute increases ranged from 9 to 40% of patient charts). CONCLUSION: This pragmatic study provides preliminary evidence for the positive influence of QI-focused education in helping rheumatologists improve performance on national quality measures for RA.
RESUMO
Conformational sampling of pre- and post-therapy subtype B HIV-1 protease sequences derived from a pediatric subject infected via maternal transmission with HIV-1 were characterized by double electron-electron resonance spectroscopy. The conformational ensemble of the PRE construct resembles native-like inhibitor bound states. In contrast, the POST construct, which contains accumulated drug-pressure selected mutations, has a predominantly semi-open conformational ensemble, with increased populations of open-like states. The single point mutant L63P, which is contained in PRE and POST, has decreased dynamics, particularly in the flap region, and also displays a closed-like conformation of inhibitor-bound states. These findings support our hypothesis that secondary mutations accumulate in HIV-1 protease to shift conformational sampling to stabilize open-like conformations, while maintaining the predominant semi-open conformation for activity.
Assuntos
Fármacos Anti-HIV/farmacologia , Protease de HIV/química , Protease de HIV/genética , HIV-1/efeitos dos fármacos , HIV-1/enzimologia , Mutação , Farmacorresistência Viral/genética , HIV-1/genética , Modelos Moleculares , Mutação Puntual , Conformação Proteica , Fatores de TempoRESUMO
Interleukin-6 (IL-6) is a pleiotropic cytokine that regulates immune and inflammatory responses, and its overproduction is a hallmark of inflammatory diseases. Inhibition of IL-6 signaling with the anti-IL-6 receptor antibody tocilizumab has provided some clinical benefit to patients; however, direct cytokine inhibition may be a more effective option. We used the systematic evolution of ligands by exponential enrichment (SELEX) process to discover slow off-rate modified aptamers (SOMAmers) with hydrophobic base modifications that inhibit IL-6 signaling in vitro. Two classes of IL-6 SOMAmers were isolated from modified DNA libraries containing 40 random positions and either 5-(N-benzylcarboxamide)-2'-deoxyuridine (Bn-dU) or 5-[N-(1-naphthylmethyl)carboxamide]-2'-deoxyuridine (Nap-dU) replacing dT. These modifications facilitate the high affinity binding interaction with IL-6 and provide resistance against degradation by serum endonucleases. Post-SELEX optimization of one Bn-dU and one Nap-dU SOMAmer led to improvements in IL-6 binding (10-fold) and inhibition activity (greater than 20-fold), resulting in lead SOMAmers with sub-nanomolar affinity (Kd = 0.2 nm) and potency (IC50 = 0.2 nm). Although similar in inhibition properties, the two SOMAmers have unique sequences and different ortholog specificities. Furthermore, these SOMAmers were stable in human serum in vitro for more than 48 h. Both SOMAmers prevented IL-6 signaling by blocking the interaction of IL-6 with its receptor and inhibited the proliferation of tumor cells in vitro as effectively as tocilizumab. This new class of IL-6 inhibitor may be an effective therapeutic alternative for patients suffering from inflammatory diseases.
Assuntos
Anti-Inflamatórios/farmacologia , Aptâmeros de Nucleotídeos/farmacologia , Interleucina-6/antagonistas & inibidores , Interleucina-6/imunologia , Receptores de Interleucina-6/imunologia , Sequência de Aminoácidos , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/metabolismo , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/metabolismo , Sequência de Bases , Células CHO , Cricetulus , Descoberta de Drogas , Humanos , Interleucina-6/química , Interleucina-6/metabolismo , Macaca fascicularis , Camundongos , Dados de Sequência Molecular , Ratos , Técnica de Seleção de Aptâmeros/métodos , Soro/metabolismoRESUMO
IL-6 is a secreted cytokine that functions through binding two cell surface receptors, IL-6Rα and gp130. Because of its involvement in the progression of several chronic inflammatory diseases, IL-6 is a target of pharmacologic interest. We have recently identified a novel class of ligands called SOMAmers (S low Off-rate Modified Aptamers) that bind IL-6 and inhibit its biologic activity. SOMAmers exploit the chemical diversity of protein-like side chains assembled on flexible nucleic acid scaffolds, resulting in an expanded repertoire of intra- and intermolecular interactions not achievable with conventional aptamers. Here, we report the co-crystal structure of a high affinity SOMAmer (Kd = 0.20 nm) modified at the 5-position of deoxyuridine in a complex with IL-6. The SOMAmer, comprised of a G-quartet domain and a stem-loop domain, engages IL-6 in a clamp-like manner over an extended surface exhibiting close shape complementarity with the protein. The interface is characterized by substantial hydrophobic interactions overlapping the binding surfaces of the IL-6Rα and gp130 receptors. The G-quartet domain retains considerable binding activity as a disconnected autonomous fragment (Kd = 270 nm). A single substitution from our diversely modified nucleotide library leads to a 37-fold enhancement in binding affinity of the G-quartet fragment (Kd = 7.4 nm). The ability to probe ligand surfaces in this manner is a powerful tool in the development of new therapeutic reagents with improved pharmacologic properties. The SOMAmer·IL-6 structure also expands our understanding of the diverse structural motifs achievable with modified nucleic acid libraries and elucidates the nature with which these unique ligands interact with their protein targets.
Assuntos
Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/farmacologia , Interleucina-6/química , Interleucina-6/metabolismo , Cristalografia por Raios X , Descoberta de Drogas , Humanos , Ligantes , Modelos Moleculares , Conformação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Técnica de Seleção de AptâmerosRESUMO
Elevated levels of circulating proinflammatory cytokines are associated with obesity and increased risk of type 2 diabetes, but the mechanism is unknown. We tested whether proinflammatory cytokines IL-1B+IL-6 at low picogram per milliliter concentrations (consistent with serum levels) could directly trigger pancreatic islet dysfunction. Overnight exposure to IL-1B+IL-6 in islets isolated from normal mice and humans disrupted glucose-stimulated intracellular calcium responses; cytokine-induced effects were more severe among islets from prediabetic db/db mice that otherwise showed no signs of dysfunction. IL-1B+IL-6 exposure reduced endoplasmic reticulum (ER) calcium storage, activated ER stress responses (Nos2, Bip, Atf4, and Ddit3 [CHOP]), impaired glucose-stimulated insulin secretion, and increased cell death only in islets from prediabetic db/db mice. Furthermore, we found increased serum levels of IL-1B and IL-6 in diabetes-prone mice at an age before hyperglycemia was exhibited, suggesting that low-grade systemic inflammation develops early in the disease process. In addition, we implanted normal outbred and inbred mice with subcutaneous osmotic mini-pumps containing IL-1B+IL-6 to mimic the serum increases found in prediabetic db/db mice. Both IL-1B and IL-6 were elevated in serum from cytokine-pump mice, but glucose tolerance and blood glucose levels did not differ from controls. However, when compared with controls, isolated islets from cytokine-pump mice showed deficiencies in calcium handling and insulin secretion that were similar to observations with islets exposed to cytokines in vitro. These findings provide proof of principle that low-grade systemic inflammation is present early in the development of type 2 diabetes and can trigger ER stress-mediated islet dysfunction that can lead to islet failure.
Assuntos
Estresse do Retículo Endoplasmático , Insulina/metabolismo , Interleucina-1beta/sangue , Interleucina-6/sangue , Ilhotas Pancreáticas/metabolismo , Estado Pré-Diabético/sangue , Animais , Animais não Endogâmicos , Apoptose/efeitos dos fármacos , Sinalização do Cálcio/efeitos dos fármacos , Implantes de Medicamento , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/imunologia , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Glucose/metabolismo , Humanos , Infusões Subcutâneas , Insulina/sangue , Secreção de Insulina , Interleucina-1beta/administração & dosagem , Interleucina-1beta/efeitos adversos , Interleucina-6/administração & dosagem , Interleucina-6/efeitos adversos , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/imunologia , Masculino , Camundongos , Camundongos Endogâmicos , Camundongos Mutantes , Estado Pré-Diabético/metabolismo , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/efeitos adversos , Organismos Livres de Patógenos Específicos , Técnicas de Cultura de TecidosRESUMO
Selection of aptamers from nucleic acid libraries by in vitro evolution represents a powerful method of identifying high-affinity ligands for a broad range of molecular targets. Nevertheless, a sizeable fraction of proteins remain difficult targets due to inherently limited chemical diversity of nucleic acids. We have exploited synthetic nucleotide modifications that confer protein-like diversity on a nucleic acid scaffold, resulting in a new generation of binding reagents called SOMAmers (Slow Off-rate Modified Aptamers). Here we report a unique crystal structure of a SOMAmer bound to its target, platelet-derived growth factor B (PDGF-BB). The SOMAmer folds into a compact structure and exhibits a hydrophobic binding surface that mimics the interface between PDGF-BB and its receptor, contrasting sharply with mainly polar interactions seen in traditional protein-binding aptamers. The modified nucleotides circumvent the intrinsic diversity constraints of natural nucleic acids, thereby greatly expanding the structural vocabulary of nucleic acid ligands and considerably broadening the range of accessible protein targets.
Assuntos
Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Proteínas Proto-Oncogênicas c-sis/metabolismo , Técnica de Seleção de Aptâmeros/métodos , Motivos de Aminoácidos/genética , Becaplermina , Cristalografia por Raios X , Primers do DNA/genética , Dados de Sequência Molecular , Estrutura Molecular , Fosforilação , Ligação Proteica , Proteínas Proto-Oncogênicas c-sis/química , Análise de Sequência de DNA , Temperatura de TransiçãoRESUMO
In obesity and the early stages of type 2 diabetes (T2D), proinflammatory cytokines are mildly elevated in the systemic circulation. This low-grade systemic inflammation exposes pancreatic islets to these circulating cytokines at much lower levels than seen within the islet during insulitis. These low-dose effects have not been well described. We examined mouse islets treated overnight with a low-dose cytokine combination commonly associated with inflammation (TNF-alpha, IL-1 beta, and IFN-gamma). We then examined islet function primarily using intracellular calcium ([Ca(2+)](i)), a key component of insulin secretion and cytokine signaling. Cytokine-treated islets demonstrated several features that suggested dysfunction including excess [Ca(2+)](i) in low physiological glucose (3mM), reduced responses to glucose stimulation, and disrupted [Ca(2+)](i) oscillations. Interestingly, islets taken from young db/db mice showed similar disruptions in [Ca(2+)](i) dynamics as cytokine-treated islets. Additional studies of control islets showed that the cytokine-induced elevation in basal [Ca(2+)](i) was due to both greater calcium influx through L-type-calcium-channels and reduced endoplasmic reticulum (ER) calcium storage. Many of these cytokine-induced disruptions could be reproduced by SERCA blockade. Our data suggest that chronic low-grade inflammation produces circulating cytokine levels that are sufficient to induce beta-cell dysfunction and may play a contributing role in beta-cell failure in early T2D.
Assuntos
Sinalização do Cálcio/fisiologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Mediadores da Inflamação/fisiologia , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Acidose/metabolismo , Acidose/patologia , Animais , Cálcio/metabolismo , Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo L/fisiologia , Citocinas/metabolismo , Citocinas/toxicidade , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/patologia , Glucose/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/antagonistas & inibidores , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismoRESUMO
The antioxidant and anti-inflammatory compound AGI-1067 (succinobucol) has potential as an oral anti-diabetic agent. AGI-1067 reduces H(b)A1c, improves fasting plasma glucose, and reduces new-onset diabetes. We investigated AGI-1067 for possible effects on mouse pancreatic islets in vitro. Pretreatment with 10 microM AGI-1067 increased glucose-stimulated insulin secretion (11 mM) without affecting secretion in basal (3 mM) glucose. AGI-1067 enhanced the intracellular calcium response to glucose stimulation in 7 mM and 11 mM glucose, but had no effect in 28 mM or basal glucose. AGI-1067-pretreated islets also showed enhanced calcium responses to methyl pyruvate and alpha-ketoisocaproate at low doses, but not high doses. The AGI-1067-mediated effects on glucose-stimulated calcium were maintained during continuous diazoxide exposure, suggesting effects on the K(ATP)-channel-independent pathway. AGI-1067 also reduced cytokine-induced islet cell death and expression of iNOS, a key component in cytokine signaling. This is the first report of direct stimulatory and protective effects of a first-in-class potential anti-diabetic agent on pancreatic islets.
Assuntos
Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Probucol/análogos & derivados , Animais , Anti-Hipertensivos/farmacologia , Cálcio/metabolismo , Morte Celular/efeitos dos fármacos , Citocinas/metabolismo , Diazóxido/farmacologia , Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Humanos , Hipoglicemiantes/farmacologia , Secreção de Insulina , Ilhotas Pancreáticas/fisiologia , Cetoácidos/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico Sintase Tipo II/metabolismo , Canais de Potássio/metabolismo , Probucol/farmacologia , Tolbutamida/farmacologiaRESUMO
Obesity, hypertension, cardiovascular disease, and inflammation are closely associated with the rising incidence of diabetes mellitus. One pharmacological target that may have significant potential to lower the risk of obesity-related diseases is the angiotensin type 1 receptor (AT1R). We examined the hypothesis that the AT1R blocker valsartan reduces the metabolic consequences and inflammatory effects of a high-fat (Western) diet in mice. C57BL/6J mice were treated by oral gavage with 10 mg/kg per day of valsartan or vehicle and placed on either a standard chow or Western diet for 12 weeks. Western diet-fed mice given valsartan had improved glucose tolerance, reduced fasting blood glucose levels, and reduced serum insulin levels compared with mice fed a Western diet alone. Valsartan treatment also blocked Western diet-induced increases in serum levels of the proinflammatory cytokines interferon-gamma and monocyte chemotactic protein 1. In the pancreatic islets, valsartan enhanced mitochondrial function and prevented Western diet-induced decreases in glucose-stimulated insulin secretion. In adipose tissue, valsartan reduced Western diet-induced macrophage infiltration and expression of macrophage-derived monocyte chemotactic protein 1. In isolated adipocytes, valsartan treatment blocked or attenuated Western diet-induced changes in expression of several key inflammatory signals: interleukin 12p40, interleukin 12p35, tumor necrosis factor-alpha, interferon-gamma, adiponectin, platelet 12-lipoxygenase, collagen 6, inducible NO synthase, and AT1R. Our findings indicate that AT1R blockade with valsartan attenuated several deleterious effects of the Western diet at the systemic and local levels in islets and adipose tissue. This study suggests that AT1R blockers provide additional therapeutic benefits in the metabolic syndrome and other obesity-related disorders beyond lowering blood pressure.
Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Diabetes Mellitus Tipo 2/prevenção & controle , Gorduras na Dieta/farmacologia , Inflamação/prevenção & controle , Ilhotas Pancreáticas/efeitos dos fármacos , Tetrazóis/farmacologia , Valina/análogos & derivados , Adipócitos/efeitos dos fármacos , Adipócitos/imunologia , Adipócitos/metabolismo , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/imunologia , Tecido Adiposo/metabolismo , Ração Animal , Animais , Peso Corporal/efeitos dos fármacos , Citocinas/sangue , Citocinas/genética , Diabetes Mellitus Tipo 2/imunologia , Diabetes Mellitus Tipo 2/metabolismo , Modelos Animais de Doenças , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/imunologia , Intolerância à Glucose/imunologia , Intolerância à Glucose/metabolismo , Intolerância à Glucose/prevenção & controle , Inflamação/imunologia , Inflamação/metabolismo , Insulina/sangue , Insulina/metabolismo , Resistência à Insulina/imunologia , Secreção de Insulina , Ilhotas Pancreáticas/imunologia , Ilhotas Pancreáticas/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/metabolismo , Masculino , Síndrome Metabólica/imunologia , Síndrome Metabólica/metabolismo , Síndrome Metabólica/prevenção & controle , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Valina/farmacologia , ValsartanaRESUMO
Pancreatic islets of Langerhans secrete hormones that are vital to the regulation of blood glucose and are, therefore, a key focus of diabetes research. Purifying viable and functional islets from the pancreas for study is an intricate process. This review highlights the key elements involved with mouse and rat islet isolation, including choices of collagenase, the collagenase digestion process, purification of islets using a density gradient, and islet culture conditions. In addition, this paper reviews commonly used techniques for assessing islet viability and function, including visual assessment, fluorescent markers of cell death, glucose-stimulated insulin secretion, and intracellular calcium measurements. A detailed protocol is also included that describes a common method for rodent islet isolation that our laboratory uses to obtain viable and functional mouse islets for in vitro study of islet function, beta-cell physiology, and in vivo rodent islet transplantation. The purpose of this review is to serve as a resource and foundation for successfully procuring and purifying high-quality islets for research purposes.