The burden of the most common rheumatic disease in Colombia.

BACKGROUND: Estimating the burden of rheumatic diseases (RDs) requires proper evaluation of its lethal and nonlethal consequences. In Colombia, it is possible to find local data and Global Burden of Disease (GBD) reports that collect information from varied contexts and apply complex statistical models, but no on-site estimations are available. METHODS: This was a descriptive study on the burden of RD based on occurrence and mortality data in the general population during 2015, including information and prevalence estimations from the Community Oriented Program for the Control of Rheumatic Diseases (COPCORD) study. Disability-adjusted life years (DALYs) were estimated by combining measures of years of life lost (YLL) and years lived with disability (YLDs). For disability weight estimations among cases, different COPCORD responses were mapped using flowcharts to show the severity distribution according to GBD. All model parameters and results were validated through an expert consensus panel. RESULTS: Low back pain (LBP) was the RD with the greatest burden of disease, costing 606.05 (95% CI 502.76-716.58) DALYs per 100,000 inhabitants, followed by osteoarthritis (292.11; 95% CI 205.76-386.85) and rheumatoid arthritis (192.46, 95% CI 109.7-239.69). CONCLUSIONS: The burden of RD is as high in Colombia as in other countries of the region. The results offer an interesting tool for optimizing healthcare system design as well as for planning the distribution of human and economic resources to achieve early diagnosis and adequate care of these diseases.

Recomendaciones para reumatólogos sobre el manejo farmacológico durante la emergencia sanitaria por COVID-19: opinión de un grupo de expertos / Recommendations for rheumatologists on pharmacological management during the COVID-19 health emergency: Expert group opinion

RESUMEN La enfermedad por Coronavirus 2019 (COVID-19) es una pandemia inesperada que ha pro vocado un estado de emergencia y que ha generado cambios drásticos en los protocolos de atención clínica. Para su tratamiento se ha descrito el papel de algunos medicamen tos usados habitualmente en artritis reumatoide, lupus eritematoso sistémico y otras enfermedades autoinmunitarias sistémicas. Debido a ello, existe un inminente riesgo de desabastecimiento, por lo cual el objetivo de esta revisión narrativa y opinión de expertos es formular recomendaciones generales clínicas y administrativas sobre el manejo de pacien tes ambulatorios con enfermedad autoinmunitaria o inflamatoria sistémica en el contexto de la pandemia por COVID-19.

ABSTRACT Coronavirus 2019 (COVID-19) is an unexpected pandemic that has caused a state of emergency, as well as generating drastic changes in clinical care protocols. Some drugs commonly used in rheumatoid arthritis, systemic lupus erythematosus, and other systemic autoimmune diseases have been described for its treatment. Therefore, there is an imminent risk of shortages. The aim of this narrative review and expert opinion is to present general recommendations on the clinical and administrative management of outpatients with autoimmune or systemic inflammatory disease, in the context of the COVID-19 pandemic.

Pharmacogenetic aspects of methotrexate in a cohort of Colombian patients with rheumatoid arthritis.

Methotrexate (MTX) is the most commonly used disease-modifying antirheumatic drug for the treatment of rheumatoid arthritis (RA). However, over time, ~40% of patients may experience therapeutic failure or drug toxicity. The genetic variability of the enzymes involved in the MTX metabolic pathway seem to serve an important role in the eventual therapeutic failure or drug toxicity. Depending on the enzymes affected, the toxicity or the therapeutic response may change. The present study reports some of the polymorphisms identified in enzymes in the MTX metabolic pathway that are present in a group of Colombian patients with RA, and assesses the associations of these polymorphisms with toxicity or therapeutic response to the medication. A total of 400 patients with RA were evaluated, of which 76% were women. the average age was 60.7±13.9 years and the duration of the disease was 13.2±10.9 years. The disease activity scoring method, DAS28-CRP, was used to evaluate the therapeutic response. Toxicity was determined based on reports of adverse events during the evaluation of the patients. The single nucleotide polymorphisms (SNPs) assessed using reverse transcription-PCR in the present study were MTHFR C677T, A1298C, ATIC C347G, RFC-1-G80A, FPGS-AG and DHFR-CT. The SNPs of MTHFR C677T (P=0.05) and A1298C (P=0.048) were significantly associated with the efficacy of MTX, and DHFR-CT (P=0.01) and ATIC C347 (P=0.005) were significantly associated with documented toxicity. Haematological, hepatic or renal toxicity was not associated with any of the SNPs. The results obtained in Colombian patients with RA receiving MTX are similar to those reported in other populations; however, the SNPs associated with a lack of response previously reported in the literature were not observed in our data. The SNPs identified in the present study may be used as biomarkers to predict response to MTX in terms of efficacy and toxicity in Colombian patients with RA.

Dickkopf 1 protein circulating levels as a possible biomarker of functional disability and chronic damage in patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is an inflammatory disease characterized by joint destruction, deformity, lower functionality, and decrease in life expectancy. Wingless signaling pathway (Wnt) has been recently involved in bone homeostasis. Studies suggest that overexpression of the pathway inhibitors, like the Dickkopf 1 protein (DKK1), has been implicated in bone destruction. The objective of this study is to compare circulating levels of DKK1 in different groups of patients with disease activity (remission, low, moderate, high activity,) and functionality status. Three hundred seventy-nine patients with RA were evaluated between March 2015 and November 2016. Disease activity was evaluated by disease activity score 28 with C-reactive protein (DAS28CPR), simplified and clinical disease activity scores (SDAI, CDAI), routine assessment of patient index data 3 (RAPID3), functional status using Multidimensional Health Assessment Questionnaire (MD-HAQ), and the Steinbrocker functional classification. DKK1 levels were measured by ELISA. The mean age was 60.7 ± 13.9 years. Disease duration was 13.2 ± 10.9 years. Higher levels of DKK1 were not associated with disease activity by CDAI (p = 0.70), SDAI (p = 0.84), DAS28CRP (p = 0.80), or RAPID3 (p = 0.70). Interestingly higher levels of DKK1 were significantly associated to lower functional status evaluating by the Steinbrocker classification (p = 0,013), severe disability by MD-HAQ (p = 0,004), and variables associated with joint destruction like osteoporosis, higher titles of rheumatoid factor, smoking, and increased hospital admissions related to RA. Higher levels of DKK1 were found in patients with lower functional status. This association was not found in patients with greater disease activity by CDAI, SDAI, DAS28, and RAPID3. This could be explained by more structural damage; DKK1 could be used as a biomarker of joint destruction in RA.

Non-cytotoxic copper overload boosts mitochondrial energy metabolism to modulate cell proliferation and differentiation in the human erythroleukemic cell line K562.

Copper is integral to the mitochondrial respiratory complex IV and contributes to proliferation and differentiation, metabolic reprogramming and mitochondrial function. The K562 cell line was exposed to a non-cytotoxic copper overload to evaluate mitochondrial dynamics, function and cell fate. This induced higher rates of mitochondrial turnover given by an increase in mitochondrial fusion and fission events and in the autophagic flux. The appearance of smaller and condensed mitochondria was also observed. Bioenergetics activity included more respiratory complexes, higher oxygen consumption rate, superoxide production and ATP synthesis, with no decrease in membrane potential. Increased cell proliferation and inhibited differentiation also occurred. Non-cytotoxic copper levels can modify mitochondrial metabolism and cell fate, which could be used in cancer biology and regenerative medicine.

Adaptive responses of mitochondria to mild copper deprivation involve changes in morphology, OXPHOS remodeling and bioenergetics.

Copper is an essential cofactor of complex IV of the electron transfer chain, and it is directly involved in the generation of mitochondrial membrane potential. Its deficiency induces the formation of ROS, large mitochondria and anemia. Thus, there is a connection between copper metabolism and bioenergetics, mitochondrial dynamics and erythropoiesis. Copper depletion might end in cellular apoptosis or necrosis. However, before entering into those irreversible processes, mitochondria may execute a series of adaptive responses. Mitochondrial adaptive responses (MAR) may involve multiple and diverse mechanisms for preserving cell life, such as mitochondrial dynamics, OXPHOS remodeling and bioenergetics output. In this study, a mild copper deficiency was produced in an animal model through intraperitoneal injections of bathocuproine disulfonate in order to study the MAR. Under these conditions, a new type of mitochondrial morphology was discovered in the liver. Termed the "butternut squash" mitochondria, it coexisted with normal and swollen mitochondria. Western blot analyses of mitochondrial dynamics proteins showed an up-regulation of MFN-2 and OPA1 fusion proteins. Furthermore, isolated liver mitochondria displayed OXPHOS remodeling through a decrease in supercomplex activity with a concomitant increase at an individual level of complexes I and IV, higher respiratory rates at complex I and II levels, higher oligomycin-insensitive respiration, and lower respiratory control ratio values when compared to the control group. As expected, total ATP and ATP/ADP values were not significantly different, since animal's health was not compromised. As a whole, these results describe a compensatory and adaptive response of metabolism and bioenergetics under copper deprivation.

Copper deficiency alters cell bioenergetics and induces mitochondrial fusion through up-regulation of MFN2 and OPA1 in erythropoietic cells.

Copper is essential in cell physiology, participating in numerous enzyme reactions. In mitochondria, copper is a cofactor for respiratory complex IV, the cytochrome c oxidase. Low copper content is associated with anemia and the appearance of enlarged mitochondria in erythropoietic cells. These findings suggest a connection between copper metabolism and bioenergetics, mitochondrial dynamics and erythropoiesis, which has not been explored so far. Here, we describe that bathocuproine disulfonate-induced copper deficiency does not alter erythropoietic cell proliferation nor induce apoptosis. However it does impair erythroid differentiation, which is associated with a metabolic switch between the two main energy-generating pathways. That is, from mitochondrial function to glycolysis. Switching off mitochondria implies a reduction in oxygen consumption and ROS generation along with an increase in mitochondrial membrane potential. Mitochondrial fusion proteins MFN2 and OPA1 were up-regulated along with the ability of mitochondria to fuse. Morphometric analysis of mitochondria did not show changes in total mitochondrial biomass but rather bigger mitochondria because of increased fusion. Similar results were also obtained with human CD34+, which were induced to differentiate into red blood cells. In all, we have shown that adequate copper levels are important for maintaining proper mitochondrial function and for erythroid differentiation where the energy metabolic switch plus the up-regulation of fusion proteins define an adaptive response to copper deprivation to keep cells alive.

Apical targeting and Golgi retention signals reside within a 9-amino acid sequence in the copper-ATPase, ATP7B.

ATP7B is a copper-transporting P-type ATPase present predominantly in liver. In basal copper, hepatic ATP7B is in a post-trans-Golgi network (TGN) compartment where it loads cytoplasmic Cu(I) onto newly synthesized ceruloplasmin. When copper levels rise, the protein redistributes via unique vesicles to the apical periphery where it exports intracellular Cu(I) into bile. We want to understand the mechanisms regulating the copper-sensitive trafficking of ATP7B. Earlier, our laboratory reported the presence of apical targeting/TGN retention information within residues 1-63 of human ATP7B; deletion of these residues resulted in a mutant protein that was not efficiently retained in the post-TGN in low copper and constitutively trafficked to the basolateral membrane of polarized, hepatic WIF-B cells with and without copper (13). In this study, we used mutagenesis and adenovirus infection of WIF-B cells followed by confocal immunofluorescence microscopy analysis to identify the precise retention/targeting sequences in the context of full-length ATP7B. We also analyzed the expression of selected mutants in livers of copper-deficient and -loaded mice. Our combined results clearly demonstrate that nine amino acids, F(37)AFDNVGYE(45), comprise an essential apical targeting determinant for ATP7B in elevated copper and participate in the TGN retention of the protein under low-copper conditions. The signal is novel, does not require phosphorylation, and is highly conserved in approximately 24 species of ATP7B. Furthermore, N41S, which is part of the signal we identified, is the first and only Wilson disease-causing missense mutation in residues 1-63 of ATP7B. Expression of N41S-ATP7B in WIF-B cells severely disabled the targeting and retention of the protein. We present a working model of how this physiologically relevant signal might work.

Coordination of Rho and Rac GTPase function via p190B RhoGAP.

The Rac GTPase regulates Rho signaling in a broad range of physiological settings and in oncogenic transformation [1-3]. Here, we report a novel mechanism by which crosstalk between Rac and Rho GTPases is achieved. Activated Rac1 binds directly to p190B Rho GTPase-activating protein (RhoGAP), a major modulator of Rho signaling. p190B colocalizes with constitutively active Rac1 in membrane ruffles. Moreover, activated Rac1 is sufficient to recruit p190B into a detergent-insoluble membrane fraction, a process that is accompanied by a decrease in GTP-bound RhoA from membranes. p190B is recruited to the plasma membrane in response to integrin engagement [4]. We demonstrate that collagen type I, a potent inducer of Rac1-dependent cell motility in HeLa cells, counteracts cytoskeletal collapse resulting from overexpression of wild-type p190B, but not that resulting from overexpression of a p190B mutant specifically lacking the Rac1-binding sequence. Furthermore, this p190B mutant exhibits dramatically enhanced RhoGAP activity, consistent with a model whereby binding of Rac1 relieves autoinhibition of p190B RhoGAP function. Collectively, these observations establish that activated Rac1, through direct interaction with p190B, modulates subcellular RhoGAP localization and activity, thereby providing a novel mechanism for Rac control of Rho signaling in a broad range of physiological processes.