Investigating the dynamic nature of the ABC transporters: ABCB1 and MsbA as examples for the potential synergies of MD theory and EPR applications

ABC transporters are primary active transporters found in all kingdoms of life. Human multidrug resistance transporter ABCB1, or P-glycoprotein, has an extremely broad substrate spectrum and confers resistance against chemotherapy drug treatment in cancer cells. The bacterial ABC transporter MsbA is a lipid A flippase and a homolog to the human ABCB1 transporter, with which it partially shares its substrate spectrum. Crystal structures of MsbA and ABCB1 have been solved in multiple conformations, providing a glimpse into the possible conformational changes the transporter could be going through during the transport cycle. Crystal structures are inherently static, while a dynamic picture of the transporter in motion is needed for a complete understanding of transporter function. Molecular dynamics (MD) simulations and electron paramagnetic resonance (EPR) spectroscopy can provide structural information on ABC transporters, but the strength of these two methods lies in the potential to characterise the dynamic regime of these transporters. Information from the two methods is quite complementary. MD simulations provide an all atom dynamic picture of the time evolution of the molecular system, though with a narrow time window. EPR spectroscopy can probe structural, environmental and dynamic properties of the transporter in several time regimes, but only through the attachment sites of an exogenous spin label. In this review the synergistic effects that can be achieved by combining the two methods are highlighted, and a brief methodological background is also presented

American College of Rheumatology Provisional Criteria for Clinically Relevant Improvement in Children and Adolescents With Childhood-Onset Systemic Lupus Erythematosus

10.1002/acr.23834ARTHRITIS CARE & RESEARCH715579-59

American College of Rheumatology Provisional Criteria for Clinically Relevant Improvement in Children and Adolescents With Childhood-Onset Systemic Lupus Erythematosus

Objective: To develop a Childhood Lupus Improvement Index (CHILI) as a tool to measure response to therapy in childhood-onset systemic lupus erythematosus (cSLE), with a focus on clinically relevant improvement (CRI cSLE ). Methods: Pediatric nephrology and rheumatology subspecialists (n = 213) experienced in cSLE management were invited to define CRI cSLE and rate a total of 433 unique patient profiles for the presence/absence of CRI cSLE . Patient profiles included the following cSLE core response variables (CRVs): global assessment of patient well-being (patient-global), physician assessment of cSLE activity (MD-global), disease activity index score (here, we used the Systemic Lupus Erythematosus Disease Activity Index), urine protein-to-creatinine ratio, and Child Health Questionnaire physical summary score. Percentage and absolute changes in these cSLE-CRVs (baseline versus follow-up) were considered in order to develop candidate algorithms and validate their performance (sensitivity, specificity, area under the receiver operating characteristic curve [AUC]; range 0\u20131). Results: During an international consensus conference, unanimous agreement on a definition of CRI cSLE was achieved; cSLE experts (n = 13) concurred (100%) that the preferred CHILI algorithm considers absolute changes in the cSLE-CRVs. After transformation to a range of 0\u2013100, a CHILI score of 6554 had outstanding accuracy for identifying CRI cSLE (AUC 0.93, sensitivity 81.1%, and specificity 84.2%). CHILI scores also reflect minor, moderate, and major improvement for values exceeding 15, 68, and 92, respectively (all AUC 650.92, sensitivity 6593.1%, and specificity 6573.4%). Conclusion: The CHILI is a new, seemingly highly accurate index for measuring CRI in cSLE over time. This index is useful to categorize the degree of response to therapy in children and adolescents with cSLE

American college of rheumatology provisional criteria for clinically relevant improvement in children and adolescents with childhood-onset systemic Lupus erythematosus

To develop a Childhood Lupus Improvement Index (CHILI) as a tool to measure response to therapy in childhood-onset systemic lupus erythematosus (cSLE), with a focus on clinically relevant improvement (CRIcSLE). Methods Pediatric nephrology and rheumatology subspecialists (n = 213) experienced in cSLE management were invited to define CRIcSLE and rate a total of 433 unique patient profiles for the presence/absence of CRIcSLE. Patient profiles included the following cSLE core response variables (CRVs): global assessment of patient well-being (patient-global), physician assessment of cSLE activity (MD-global), disease activity index score (here, we used the Systemic Lupus Erythematosus Disease Activity Index), urine protein-to-creatinine ratio, and Child Health Questionnaire physical summary score. Percentage and absolute changes in these cSLE-CRVs (baseline versus follow-up) were considered in order to develop candidate algorithms and validate their performance (sensitivity, specificity, area under the receiver operating characteristic curve [AUC]; range 0-1). Results During an international consensus conference, unanimous agreement on a definition of CRIcSLE was achieved; cSLE experts (n = 13) concurred (100%) that the preferred CHILI algorithm considers absolute changes in the cSLE-CRVs. After transformation to a range of 0-100, a CHILI score of >= 54 had outstanding accuracy for identifying CRIcSLE (AUC 0.93, sensitivity 81.1%, and specificity 84.2%). CHILI scores also reflect minor, moderate, and major improvement for values exceeding 15, 68, and 92, respectively (all AUC >= 0.92, sensitivity >= 93.1%, and specificity >= 73.4%). Conclusion The CHILI is a new, seemingly highly accurate index for measuring CRI in cSLE over time. This index is useful to categorize the degree of response to therapy in children and adolescents with cSLE.715579590CNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo303422/2015-7; 7/2016-9; 304255/2015-7215/03756-