Role of the mechanisms for antibody repertoire diversification in monoclonal light chain deposition disorders: when a friend becomes foe.

The adaptive immune system of jawed vertebrates generates a highly diverse repertoire of antibodies to meet the antigenic challenges of a constantly evolving biological ecosystem. Most of the diversity is generated by two mechanisms: V(D)J gene recombination and somatic hypermutation (SHM). SHM introduces changes in the variable domain of antibodies, mostly in the regions that form the paratope, yielding antibodies with higher antigen binding affinity. However, antigen recognition is only possible if the antibody folds into a stable functional conformation. Therefore, a key force determining the survival of B cell clones undergoing somatic hypermutation is the ability of the mutated heavy and light chains to efficiently fold and assemble into a functional antibody. The antibody is the structural context where the selection of the somatic mutations occurs, and where both the heavy and light chains benefit from protective mechanisms that counteract the potentially deleterious impact of the changes. However, in patients with monoclonal gammopathies, the proliferating plasma cell clone may overproduce the light chain, which is then secreted into the bloodstream. This places the light chain out of the protective context provided by the quaternary structure of the antibody, increasing the risk of misfolding and aggregation due to destabilizing somatic mutations. Light chain-derived (AL) amyloidosis, light chain deposition disease (LCDD), Fanconi syndrome, and myeloma (cast) nephropathy are a diverse group of diseases derived from the pathologic aggregation of light chains, in which somatic mutations are recognized to play a role. In this review, we address the mechanisms by which somatic mutations promote the misfolding and pathological aggregation of the light chains, with an emphasis on AL amyloidosis. We also analyze the contribution of the variable domain (VL) gene segments and somatic mutations on light chain cytotoxicity, organ tropism, and structure of the AL fibrils. Finally, we analyze the most recent advances in the development of computational algorithms to predict the role of somatic mutations in the cardiotoxicity of amyloidogenic light chains and discuss the challenges and perspectives that this approach faces.

[Risk factors for metabolic dysfunction-associated fatty liver disease in the Hispanic-Mexican population.] / Factores de riesgo de la enfermedad hepática grasa asociada a disfunción metabólica en población hispano-mexicana.

OBJECTIVE: Metabolic dysfunction-associated fatty liver disease (MAFLD) is a poor attended disease, which has gained attention due the elevated number of cases in countries as Mexico, where the incidence is the number 4th globally. MAFLD develops in obese or overweighted individuals and is characterized by triglycerides accumulation in the liver, this condition can develop to hepatocellular carcinoma. It has been observed that MAFLD depends on the genetics and lifestyle. Due to the high prevalence of this disease among Hispanic population, we focused on this study in the characteristics and prevalence of MAFLD in Mexican patients. METHODS: In this study were included 572 overweighted and obese patients, who underwent a screening analysis using the fatty liver index (IHG), clinical parameters were analysed, demographic and comorbidities. Frequency of variables were obtained, and the data were analysed by Chi-square test or Fisher test, odd ratio (OR) and binary logistic regression. RESULTS: A MALFD prevalence of 37% were obtained, where the history of familiar obesity, paracetamol usage, carbohydrate and fat intake are shown to be risk factors. It was found that high blood pressure, central obesity and hypertriglyceridemia were also associated to the MAFLD development. On the other hand, physical exercise was a protector factor. CONCLUSIONS: Our results show the necessity to study the MAFLD causalities in Mexican patients, focused on the paracetamol intake.

OBJETIVO: La enfermedad hepática grasa asociada a disfunción metabólica (MAFLD) es una enfermedad poco considerada, que ha recibido atención debido al número de casos en países como México, donde ocupa el 4º lugar mundial de incidencia. La MAFLD se desarrolla en personas con sobrepeso u obesidad y se caracteriza por la acumulación de triglicéridos en el hígado, donde puede evolucionar hacia carcinoma hepatocelular. Se ha observado que la MAFLD depende de la genética y del estilo de vida. Tomando en cuenta la alta prevalencia de MAFLD en la población hispana, nos enfocamos en este trabajo en estudiar la prevalencia y características relacionadas con esta enfermedad en pacientes mexicanos. METODOS: En este estudio se incluyeron 572 pacientes con sobrepeso u obesidad, a los cuales se les realizó un análisis de cribado mediante el índice de hígado graso (IHG), se analizaron parámetros clínicos, demográficos y comorbilidades. Se obtuvieron frecuencias de las variables y se analizaron los datos mediante chi cuadrado o exacta de Fisher, razón de momios (OR) y regresión logística binaria. RESULTADOS: Se obtuvo una prevalencia del 37% de MAFLD, donde la historia familiar de obesidad, el uso de paracetamol, así como el consumo de carbohidratos y grasas fueron factores de riesgo para su desarrollo. Se encontró que la hipertensión arterial, la obesidad visceral y la hipertrigliceridemia también estaban asociados al desarrollo de la MAFLD. Por otro lado, el ejercicio fue un factor protector. CONCLUSIONES: Nuestros resultados ponen de manifiesto la necesidad de realizar estudios relacionados con las causalidades de la MAFLD en los pacientes mexicanos, principalmente en el uso del paracetamol.

Efficacy of nutrition therapy with food rich in methionine for treating nonalcoholic fatty liver / Eficacia de la terapia nutricional con alimentos ricos en metionina para el tratamiento de hígado graso no alcohólico

Non-Alcoholic Fatty Liver disease (NAFLD) can lead to Non Alcoholic steatohepatitis (NASH), cirrhosis, and liver cancer. The treatment for NAFLD involves modification of caloric intake and physical activity. NAFLD has a pro-oxidant nature; therefore, it is logical to suppose that the antioxidant methionine can be used as a treatment for this disease. Aim. This study aimed to evaluate the effect of high-methionine dietary therapy on patients with NAFLD. Materials and methods. A randomized clinical study was conducted over three months. In this study, 121 NAFLD patients participated, and the age of the participants was ≥ 20 years (experimental group included 56 and control group 65), all of whom were randomized and matched by sex, recluted from the ISSSTE hospital in Xalapa, Mexico. The patients were instructed to consume food to cover the recommended methionine daily doses, and the daily amount consumed was calculated. Methionine effect was measured as NAFLD regression and quality of life improvement. Results. Nutritional therapy induced NAFLD regression and diminished central fat accumulation, blood pressure, and the fatty liver index. Some parameters, such as liver enzymes, did not changed. The quality of life of patients improved after treatment. Conclusions. In this study, we show a hepatoprotective effect induced only in three months of chances in the diet, thus, a longer diet may generate more relevant benefits in the resistant parameters of our study(AU)

La enfermedad del hígado graso no alcohólico (NAFLD) puede conducir a la esteatohepatitis no alcohólica (NASH), la cirrosis y el cáncer de hígado. El tratamiento para NAFLD es la modificación de la ingesta calórica y la actividad física. Debido a que NAFLD tiene una naturaleza pro-oxidante; es lógico suponer que el antioxidante metionina puede utilizarse en el tratamiento de esta enfermedad. Objetivo. el presente trabajo evaluó el papel de la terapia nutricional con alimentos ricos en metioninaen pacientes con NAFLD. Materiales y Métodos. Se realizó un ensayo clínico aleatorizado durante tres meses. Participaron en el estudio 121 pacientes con NAFLD con edad ≥ 20 años (56 en el grupo experimental y 65 en el control), todos aleatorizados y pareados por sexo, reclutados de la Clínica Hospital ISSTE en la ciudad de Xalapa, México, en el año 2015. Se instruyó a los pacientes en consumir los alimentos hasta completar la dosis diaria recomendada de metioninay se calculó la cantidad diaria consumida. Su efecto se midió como la regresión de NAFLD y la mejora de la calidad de vida. Resultados. La terapia nutricional retrocedió NAFLD; disminuyó la acumulación de grasa central, la presión arterial y el índice de hígado graso. Algunos parámetros, como las enzimas de la función hepática, no se modificaron con el tratamiento. Otro parámetro fue la mejora de la calidad de vida de los pacientes tratados. Conclusiones. En este trabajo mostramos un impacto hepatoprotector producido con tan solo tres meses de cambios en la dieta, por lo que una dieta más prolongada podría generar beneficios aún más significativos en los parámetros resistentes en nuestro protocolo(AU)

Factores de riesgo de la enfermedad hepática grasa asociada a disfunción metabólica en población hispano-mexicana / Risk factors for metabolic dysfunction-associated fatty liver disease in the Hispanic-Mexican population

FUNDAMENTOS: La enfermedad hepática grasa asociada a disfunción metabólica (MAFLD) es una enfermedad poco considerada,que ha recibido atención debido al número de casos en países como México, donde ocupa el 4º lugar mundial de incidencia. La MAFLDse desarrolla en personas con sobrepeso u obesidad y se caracteriza por la acumulación de triglicéridos en el hígado, donde puedeevolucionar hacia carcinoma hepatocelular. Se ha observado que la MAFLD depende de la genética y del estilo de vida. Tomando encuenta la alta prevalencia de MAFLD en la población hispana, nos enfocamos en este trabajo en estudiar la prevalencia y características relacionadas con esta enfermedad en pacientes mexicanos. MÉTODOS: En este estudio se incluyeron 572 pacientes con sobrepeso u obesidad, a los cuales se les realizó un análisis de cribadomediante el índice de hígado graso (IHG), se analizaron parámetros clínicos, demográficos y comorbilidades. Se obtuvieron frecuenciasde las variables y se analizaron los datos mediante chi cuadrado o exacta de Fisher, razón de momios (OR) y regresión logística binaria. RESULTADOS: Se obtuvo una prevalencia del 37% de MAFLD, donde la historia familiar de obesidad, el uso de paracetamol, así comoel consumo de carbohidratos y grasas fueron factores de riesgo para su desarrollo. Se encontró que la hipertensión arterial, la obesidadvisceral y la hipertrigliceridemia también estaban asociados al desarrollo de la MAFLD. Por otro lado, el ejercicio fue un factor protector. CONCLUSIONES: Nuestros resultados ponen de manifiesto la necesidad de realizar estudios relacionados con las causalidades dela MAFLD en los pacientes mexicanos, principalmente en el uso del paracetamol.(AU)

BACKGROUND: Metabolic dysfunction-associated fatty liver disease (MAFLD) is a poor attended disease, which has gained at-tention due the elevated number of cases in countries as Mexico, where the incidence is the number 4 th globally. MAFLD developsin obese or overweighted individuals and is characterized by triglycerides accumulation in the liver, this condition can develop tohepatocellular carcinoma. It has been observed that MAFLD depends on the genetics and lifestyle. Due to the high prevalence of thisdisease among Hispanic population, we focused on this study in the characteristics and prevalence of MAFLD in Mexican patients. METHODS: In this study were included 572 overweighted and obese patients, who underwent a screening analysis using the fatty liverindex (IHG), clinical parameters were analysed, demographic and comorbidities. Frequency of variables were obtained, and the data wereanalysed by Chi-square test or Fisher test, odd ratio (OR) and binary logistic regression. RESULTS: A MALFD prevalence of 37% were obtained, where the history of familiar obesity, paracetamol usage, carbohydrate andfat intake are shown to be risk factors. It was found that high blood pressure, central obesity and hypertriglyceridemia were alsoassociated to the MAFLD development. On the other hand, physical exercise was a protector factor. CONCLUSIONS: Our results show the necessity to study the MAFLD causalities in Mexican patients, focused on the paracetamol intake.(AU)

Incorporation of Bifidobacterium sp. into powder products through a fluidized bed process for enteric targeted release.

Considering the increase in evidence regarding the benefits of probiotics on human health, there is interest in developing solid products with proper functional characteristics, such as temperature and pH stability, that can be added to oral solid dosage forms or to dairy products to release microorganisms directly at their site of action. The aim of this work was to develop a product with an enteric coat containing probiotics that is stable at room temperature and resists low pH to ensure that the probiotics are passed through the stomach and reach the colon. We obtained 2 enteric-release products based on the incorporation of Bifidobacterium sp. using commercial microcrystalline cellulose (BIP-Av) and prebiotic inulin (BIP-In) as cores. Both products had an initial concentration of approximately 1 × 108 bifidobacteria per gram (cfu/g) and showed a suitable resistance to acid; complete release from the products at a pH of 7.5 was observed at 120 min for BIP-In and 180 min for BIP-Av. The viability of bacteria in both products decreased by approximately 3 orders of magnitude. The death rate constant corresponded to 0.1143 for BIP-Av and 0.1466 for BIP-In, which means that in these storage conditions, the viability decreased slightly. Both products protected bifidobacteria for more than 2 yr, delivering a concentration of more than 1 × 105 cfu/g. Due to these characteristics, the products could be incorporated into solid pharmaceutical forms for oral administration. These products could have significant advantages over existing products on the market and provide protection for bacteria, allowing their passage through the stomach to reach the colon, and the viability of bacteria was maintained after storage at room temperature for more than 1 yr.

The CDR1 and Other Regions of Immunoglobulin Light Chains are Hot Spots for Amyloid Aggregation.

Immunoglobulin light chain-derived (AL) amyloidosis is a debilitating disease without known cure. Almost nothing is known about the structural factors driving the amyloidogenesis of the light chains. This study aimed to identify the fibrillogenic hotspots of the model protein 6aJL2 and in pursuing this goal, two complementary approaches were applied. One of them was based on several web-based computational tools optimized to predict fibrillogenic/aggregation-prone sequences based on different structural and biophysical properties of the polypeptide chain. Then, the predictions were confirmed with an ad-hoc synthetic peptide library. In the second approach, 6aJL2 protein was proteolyzed with trypsin, and the products incubated in aggregation-promoting conditions. Then, the aggregation-prone fragments were identified by combining standard proteomic methods, and the results validated with a set of synthetic peptides with the sequence of the tryptic fragments. Both strategies coincided to identify a fibrillogenic hotspot located at the CDR1 and ß-strand C of the protein, which was confirmed by scanning proline mutagenesis analysis. However, only the proteolysis-based strategy revealed additional fibrillogenic hotspots in two other regions of the protein. It was shown that a fibrillogenic hotspot associated to the CDR1 is also encoded by several κ and λ germline variable domain gene segments. Some parts of this study have been included in the chapter "The Structural Determinants of the Immunoglobulin Light Chain Amyloid Aggregation", published in Physical Biology of Proteins and Peptides, Springer 2015 (ISBN 978-3-319-21687-4).

The N-terminal strand modulates immunoglobulin light chain fibrillogenesis.

It has been suggested that the N-terminal strand of the light chain variable domain (V(L)) protects the molecule from aggregation by hindering spurious intermolecular contacts. We evaluated the impact of mutations in the N-terminal strand on the thermodynamic stability and kinetic of fibrillogenesis of the V(L) protein 6aJL2. Mutations in this strand destabilized the protein in a position-dependent manner, accelerating the fibrillogenesis by shortening the lag time; an effect that correlated with the extent of destabilization. In contrast, the effect on the kinetics of fibril elongation, as assessed in seeding experiments was of different nature, as it was not directly dependant on the degree of destabilization. This finding suggests different factors drive the nucleation-dependent and elongation phases of light chain fibrillogenesis. Finally, taking advantage of the dependence of the Trp fluorescence upon environment, four single Trp substitutions were made in the N-terminal strand, and changes in solvent exposure during aggregation were evaluated by acrylamide-quenching. The results suggest that the N-terminal strand is buried in the fibrillar state of 6aJL2 protein. This finding suggest a possible explanation for the modulating effect exerted by the mutations in this strand on the aggregation behavior of 6aJL2 protein.

Mutational and genetic determinants of λ6 light chain amyloidogenesis.

Approximately 25% of the λ6 light chains have glycine rather than arginine at position 25, which is an allelic variant of the IGLV6-57 (6a) locus. The Gly25 variant has been shown to decrease the folding stability of the germline λ6 V(L) protein 6aJL2 by 1.7 kcal·mol(-1). In this work, we compared the thermodynamic and fibrillogenic properties of the amyloidosis (AL) derived recombinant (r) V(L) protein AR, which contains the allelic variant Gly25, with those of germline rV(L) 6aJL2-R25G and the λ6 disease-associated V(L) proteins Wil (AL) and Jto (myeloma). Our experiments show that of the four proteins AR is the least stable; forms amyloid fibrils at physiological temperature, pH and ionic strength; has the shortest lag time; and elongates homologous seeds most efficiently. We conclude that the Gly25 allelic variant, together with the somatic mutations, contributes importantly to the extremely low stability and high amyloidogenicity of the AL-derived protein AR.

Comparative proteomic analysis of thiol proteins in the liver after oxidative stress induced by diethylnitrosamine.

Conversion of protein -SH groups to disulfides is an early event during protein oxidation, which has prompted great interest in the study of thiol proteins. Chemical carcinogenesis is strongly associated with the formation of reactive oxygen species (ROS). The goal of this study was to detect thiol proteins that are sensitive to ROS generated during diethylnitrosamine (DEN) metabolism in the rat liver. DEN has been widely used to induce experimental hepatocellular carcinoma. We used modified redox-differential gel electrophoresis (redox-DIGE method) and mass spectrometry MALDI-TOF/TOF to identify differential oxidation protein profiles associated with carcinogen exposure. Our analysis revealed a time-dependent increase in the number of oxidized thiol proteins after carcinogen treatment; some of these proteins have antioxidant activity, including thioredoxin, peroxirredoxin 2, peroxiredoxin 6 and glutathione S-transferase alpha-3. According to functional classifications, the identified proteins in our study included chaperones, oxidoreductases, activity isomerases, hydrolases and other protein-binding partners. This study demonstrates that oxidative stress generated by DEN tends to increase gradually through DEN metabolism, causes time-dependent necrosis in the liver and has an oxidative effect on thiol proteins, thereby increasing the number of oxidized thiol proteins. Furthermore, these events occurred during the hepatocarcinogenesis initiation period.

Chemoprotective effect of caffeic acid phenethyl ester on promotion in a medium-term rat hepatocarcinogenesis assay.

Caffeic acid phenethyl ester (CAPE), a natural honeybee product exhibits a spectrum of biological activities including anti-microbial, anti-inflammatory, antioxidant and anti-tumoral actions. CAPE is also chemopreventive against intestinal, colon and skin cancer. Our aim was to extend the study of its chemoprotective features to the promotion of hepatocarcinogenesis. Male Wistar rats were subjected to a protocol under a modified promotion regimen of the resistant hepatocyte model. The altered hepatic foci (AHF) were quantitatively analyzed by histochemistry and image processing. When given during promotion, CAPE (20 mg/kg) decreased the expression of number and area gamma-glutamyl transpeptidase (GGT) positive AHF by 91% and 97%, respectively. When GGT expression was analyzed by RT-PCR, CAPE drastically decreased and prevented expression of almost all GGT transcripts at this stage of the carcinogenic process. Glutathione S-transferase placental form (GST-P), another protein marker for preneoplastic lesions was measured by Western blot and a decrease of 82% was observed. Additionally, we evaluated the effect of CAPE on the expression of nuclear factor NF-kappaB and found an 85% decrease in nuclear localization of the p65 subunit of NF-kappaB; however, their repressor, IkappaBalpha was not modified. Our results showed that CAPE given during promotion in hepatocarcinogenesis protects against induction of GGT-positive AHF, GST-P protein, GGT mRNA expression and translocation of p65. This phenomenon was independent of IkappaBalpha degradation.