Mice Overexpressing Wild-Type RRAS2 Are a Novel Model for Preclinical Testing of Anti-Chronic Lymphocytic Leukemia Therapies.

B-cell chronic lymphocytic leukemia (B-CLL) is the most common type of leukemia in the Western world. Mutation in different genes, such as TP53 and ATM, and deletions at specific chromosomic regions, among which are 11q or 17p, have been described to be associated to worse disease prognosis. Recent research from our group has demonstrated that, contrary to what is the usual cancer development process through missense mutations, B-CLL is driven by the overexpression of the small GTPase RRAS2 in its wild-type form without activating mutations. Some mouse models of this disease have been developed to date and are commonly used in B-CLL research, but they present different disadvantages such as the long waiting period until the leukemia fully develops, the need to do cell engraftment or, in some cases, the fact that the model does not recapitulate the alterations found in human patients. We have recently described Rosa26-RRAS2fl/flxmb1-Cre as a new mouse model of B-CLL with a full penetrance of the disease. In this work, we have validated this mouse model as a novel tool for the development of new therapies for B-CLL, by testing two of the most broadly applied targeted agents: ibrutinib and venetoclax. This also opens the door to new targeted agents against R-RAS2 itself, an approach not yet explored in the clinic.

Fertilización asistida con óvulos donados: indicaciones y resultados

Las mujeres retrasan cada vez más la maternidad por diferentes motivos, lo que les ocasiona recurrir a tratamientos de fertilización in vitro (FIV) con óvulos propios u óvulos donados para conseguir embarazo. En los tratamientos de FIV con óvulos donados se realiza una selección estricta de las donantes, quienes son sometidas a estimulación ovárica con posterior aspiración de los folículos. La edad recomendada para donar es entre 21 y 34 años. Se recomienda un máximo de 6 donaciones por donante. La receptora es la persona a quien se le realizará la transferencia del embrión y llevará el embarazo. Las tasas de embarazo con esta técnica de reproducción asistida son altas y las indicaciones más frecuentes son edad materna avanzada y falla ovárica precoz.

Women are increasingly delaying childbearing for different reasons, which causes them to resort to in vitro fertilization (IVF) treatments with their own oocytes or donated oocytes to achieve pregnancy. In IVF treatments with donated oocytes, donors are strictly selected and undergo ovarian stimulation with subsequent follicle aspiration. The recommended age to donate is between 21-34 years old. A maximum of 6 donations per donor is recommended. The recipient is the person to whom the embryo transfer will be performed and who will carry the pregnancy. Pregnancy rates with this assisted reproduction technique are high and the most frequent indications are advanced maternal age and early ovarian failure.

Overexpression of wild type RRAS2, without oncogenic mutations, drives chronic lymphocytic leukemia.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is the most frequent, and still incurable, form of leukemia in the Western World. It is widely accepted that cancer results from an evolutionary process shaped by the acquisition of driver mutations which confer selective growth advantage to cells that harbor them. Clear examples are missense mutations in classic RAS genes (KRAS, HRAS and NRAS) that underlie the development of approximately 13% of human cancers. Although autonomous B cell antigen receptor (BCR) signaling is involved and mutations in many tumor suppressor genes and oncogenes have been identified, an oncogenic driver gene has not still been identified for CLL. METHODS: Conditional knock-in mice were generated to overexpress wild type RRAS2 and prove its driver role. RT-qPCR analysis of a human CLL sample cohort was carried out to measure RRAS2 transcriptional expression. Sanger DNA sequencing was used to identify a SNP in the 3'UTR region of RRAS2 in human CLL samples. RNAseq of murine CLL was carried out to identify activated pathways, molecular mechanisms and to pinpoint somatic mutations accompanying RRAS2 overexpression. Flow cytometry was used for phenotypic characterization and shRNA techniques to knockdown RRAS2 expression in human CLL. RESULTS: RRAS2 mRNA is found overexpressed in its wild type form in 82% of the human CLL samples analyzed (n = 178, mean and median = 5-fold) as well as in the explored metadata. A single nucleotide polymorphism (rs8570) in the 3'UTR of the RRAS2 mRNA has been identified in CLL patients, linking higher expression of RRAS2 with more aggressive disease. Deliberate overexpression of wild type RRAS2 in mice, but not an oncogenic Q72L mutation in the coding sequence, provokes the development of CLL. Overexpression of wild type RRAS2 in mice is accompanied by a strong convergent selection of somatic mutations in genes that have been identified in human CLL. R-RAS2 protein is physically bound to the BCR and mediates BCR signals in CLL. CONCLUSIONS: The results indicate that overexpression of wild type RRAS2 is behind the development of CLL.

Evolution of antibody immunity to SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected 78 million individuals and is responsible for over 1.7 million deaths to date. Infection is associated with the development of variable levels of antibodies with neutralizing activity, which can protect against infection in animal models1,2. Antibody levels decrease with time, but, to our knowledge, the nature and quality of the memory B cells that would be required to produce antibodies upon reinfection has not been examined. Here we report on the humoral memory response in a cohort of 87 individuals assessed at 1.3 and 6.2 months after infection with SARS-CoV-2. We find that titres of IgM and IgG antibodies against the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 decrease significantly over this time period, with IgA being less affected. Concurrently, neutralizing activity in plasma decreases by fivefold in pseudotype virus assays. By contrast, the number of RBD-specific memory B cells remains unchanged at 6.2 months after infection. Memory B cells display clonal turnover after 6.2 months, and the antibodies that they express have greater somatic hypermutation, resistance to RBD mutations and increased potency, indicative of continued evolution of the humoral response. Immunofluorescence and PCR analyses of intestinal biopsies obtained from asymptomatic individuals at 4 months after the onset of coronavirus disease 2019 (COVID-19) revealed the persistence of SARS-CoV-2 nucleic acids and immunoreactivity in the small bowel of 7 out of 14 individuals. We conclude that the memory B cell response to SARS-CoV-2 evolves between 1.3 and 6.2 months after infection in a manner that is consistent with antigen persistence.

Combination anti-HIV-1 antibody therapy is associated with increased virus-specific T cell immunity.

Combination antiretroviral therapy (ART) is highly effective in controlling human immunodeficiency virus (HIV)-1 but requires lifelong medication due to the existence of a latent viral reservoir1,2. Potent broadly neutralizing antibodies (bNAbs) represent a potential alternative or adjuvant to ART. In addition to suppressing viremia, bNAbs may have T cell immunomodulatory effects as seen for other forms of immunotherapy3. However, this has not been established in individuals who are infected with HIV-1. Here, we document increased HIV-1 Gag-specific CD8+ T cell responses in the peripheral blood of all nine study participants who were infected with HIV-1 with suppressed blood viremia, while receiving bNAb therapy during ART interruption4. Increased CD4+ T cell responses were detected in eight individuals. The increased T cell responses were due both to newly detectable reactivity to HIV-1 Gag epitopes and the expansion of pre-existing measurable responses. These data demonstrate that bNAb therapy during ART interruption is associated with enhanced HIV-1-specific T cell responses. Whether these augmented T cell responses can contribute to bNAb-mediated viral control remains to be determined.

R-Ras2 is required for germinal center formation to aid B cells during energetically demanding processes.

Upon antigen recognition within peripheral lymphoid organs, B cells interact with T cells and other immune cells to transiently form morphological structures called germinal centers (GCs), which are required for B cell clonal expansion, immunoglobulin class switching, and affinity maturation. This process, known as the GC response, is an energetically demanding process that requires the metabolic reprogramming of B cells. We showed that the Ras-related guanosine triphosphate hydrolase (GTPase) R-Ras2 (also known as TC21) plays an essential, nonredundant, and B cell-intrinsic role in the GC response. Both the conversion of B cells into GC B cells and their expansion were impaired in mice lacking R-Ras2, but not in those lacking a highly related R-Ras subfamily member or both the classic H-Ras and N-Ras GTPases. In the absence of R-Ras2, activated B cells did not exhibit increased oxidative phosphorylation or aerobic glycolysis. We showed that R-Ras2 was an effector of both the B cell receptor (BCR) and CD40 and that, in its absence, B cells exhibited impaired activation of the PI3K-Akt-mTORC1 pathway, reduced mitochondrial DNA replication, and decreased expression of genes involved in glucose metabolism. Because most human B cell lymphomas originate from GC B cells or B cells that have undergone the GC response, our data suggest that R-Ras2 may also regulate metabolism in B cell malignancies.

Identificación de plantas medicinales usadas en fitoterapia animal, en la ciudad de Jenaro Herrera, bajo Ucayali, Loreto. Perú. 2015 / Identification of medicinal plants used in animal herbal medicine, in the city of Jenaro Herrera, under Ucayali, Loreto. Peru. 2015

El área de estudio se localiza en el distrito de Jenaro Herrera, el cual se ubica en la margen derecha del río Ucayali, al norte de la provincia de Requena, Región Loreto. La capital del distrito es la localidad de Villa Jenaro Herrera y está ubicado en las siguientes coordenadas: 04°54 ´13.2" de latitud sur y 73°40 ´13.6" de longitud oeste, con una altitud de 98 m.s.n.m. El objetico del presente estudio fue Identificar especies vegetales de uso medicinal veterinario, formas de aprovechamiento e impacto de la extracción en la ciudad de Jenaro Herrera. 2015. Las plantas medicinales se extraen sin depredar las mismas, puesto que se extrae lo necesario sin alterar la especie. Como no existen empresas farmacéuticas dedicadas al rubro las especies se mantienen constante siempre en sus hábitats. Según sea la parte ha utilizar se extrae el recurso, en el caso de cortezas, solo se extraen partes del tallo o se rallan los mismos en el árbol de pie. Los frutos se cosechan maduros o se espera que los mismos se desprendan naturalmente y se recogen del suelo. Las hojas se recolectan manualmente y solo lo necesario, si se cosecha la planta se deja los "hijuelos" matas, para que continúe la regeneración espontánea. Se registraron 31 especies de flora utilizadas para medicina veterinaria. Se encuentran destacándose según los encuestados el 76,3% para el tratamiento de males y 23,7% en actividades de shamanismo. Destacan como la más usada y conocida el ajo sacha (Mansoa alliaceae) y otras especies como la malva (Malchra alicifolia Jacq) y mucura (Petiveria alliaceae L). Las partes más utilizadas son las hojas, frutos y corteza. La mayor utilización que las personas de esta comunidad dan a las plantas está dirigida al tratamiento de enfermedades gastrointestinales como las diarreas, bronquitis o tos y micosis. Las dosis o medidas corresponden a unidades como: cucharadas soperas (90 gotas 0 15 cc), puñados (45.50 gramos), vaso de vidrio común (150 cc), gramo de agua (20 gotas), 1 cucharita de té (20 gotas o 5 cc).