Browsing by Author "Hormazábal, Juan"
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Item Chaperone mediated autophagy contributes to the newly synthesized histones H3 and H4 quality control(2022) Hormazábal, Juan; Saavedra, Francisco; Espinoza, Claudia; Martínez, Nicolás; Cruces, Tatiana; Iván, Alfaro; Loyola, AlejandraAlthough there are several pathways to ensure that proteins are folded properly in the cell, little is known about the molecular mechanisms regulating histone folding and proteostasis. In this work, we identified that chaperone-mediated autophagy (CMA) is the main pathway involved in the degradation of newly synthesized histones H3 and H4. This degradation is finely regulated by the interplay between HSC70 and tNASP, two histone interacting proteins. tNASP stabilizes histone H3 levels by blocking the direct transport of histone H3 into lysosomes. We further demonstrate that CMA degrades unfolded histone H3. Thus, we reveal that CMA is the main degradation pathway involved in the quality control of histone biogenesis, evidencing an additional mechanism in the intricate network of histone cellular proteostasis.Item Chaperone Mediated Autophagy Degrades TDP-43 Protein and Is Affected by TDP-43 Aggregation(2020) Alfaro, Iván; Ormeño, Fernando; Hormazábal, Juan; Moreno, José; Riquelme, Felipe; Ríos, Javiera; Criollo, Alfredo; Albornoz, Amelina; Budini, MauricioTAR DNA binding protein 43 kDa (TDP-43) is a ribonuclear protein regulating many aspects of RNA metabolism. Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Lobar Degeneration (FTLD) are fatal neurodegenerative diseases with the presence of TDP-43 aggregates in neuronal cells. Chaperone Mediated Autophagy (CMA) is a lysosomal degradation pathway participating in the proteostasis of several cytosolic proteins including neurodegenerative associated proteins. In addition, protein oligomers or aggregates can affect the status of CMA. In this work, we studied the relationship between CMA and the physiological and pathological forms of TDP-43. First, we found that recombinant TDP-43 was specifically degraded by rat liver’s CMA+ lysosomes and that endogenous TDP-43 is localized in rat brain’s CMA+ lysosomes, indicating that TDP-43 can be a CMA substrate in vivo. Next, by using a previously reported TDP-43 aggregation model, we have shown that wild-type and an aggregate-prone form of TDP-43 are detected in CMA+ lysosomes isolated from cell cultures. In addition, their protein levels increased in cells displaying CMA down-regulation, indicating that these two TDP-43 forms are CMA substrates in vitro. Finally, we observed that the aggregate-prone form of TDP-43 is able to interact with Hsc70, to co-localize with Lamp2A, and to up-regulate the levels of these molecular components of CMA. The latter was followed by an up-regulation of the CMA activity and lysosomal damage. Altogether our data shows that: (i) TDP-43 is a CMA substrate; (ii) CMA can contribute to control the turnover of physiological and pathological forms of TDP-43; and (iii) TDP-43 aggregation can affect CMA performance. Overall, this work contributes to understanding how a dysregulation between CMA and TDP-43 would participate in neuropathological mechanisms associated with TDP-43 aggregation.Publication Deep immunophenotyping reveals biomarkers of multisystemic inflammatory syndrome in children in a Latin American cohort(2022) Rey, Emma; Espinosa, Yazmin; Astudillo, Camila; Jimena, Lina; Hormazábal, Juan; Noguera, Loreani; Cofré, Fernanda; Piñera, Cecilia; González, Ricardo; Bataszew, Alexander; Muñoz, Paula; Benadof, Dona; Álvarez, Patricia; Acevedo, Valeria; Vial, Pablo; Vial, Cecilia; Poli, CeciliaBackground: Multisystemic inflammatory syndrome in children (MIS-C) is a life-threatening disease that occurs 2-5 weeks after severe acute respiratory syndrome coronavirus 2 exposure and is characterized by severe multisystemic inflammation. Early recognition of MIS-C is key to prognosis; therefore, establishing clinical and laboratory biomarkers that predict complications is urgently needed. Objective: We characterized the immune response and clinical features of patients with acute MIS-C and determined biomarkers of disease in a cohort of 42 Latin American patients. Methods: Immune characterization was performed using flow cytometry from peripheral mononuclear cells and severe acute respiratory syndrome coronavirus 2-specific humoral and cellular response was performed using flow cytometry, enzyme-linked immunospot, enzyme-linked immunosorbent assay, and neutralizing antibody assays. Results: MIS-C is characterized by robust T-cell activation and cytokine storm. We uncovered that while C-X-C motif chemokine ligand (CXCL) 9, IL-10, CXCL8, CXCL10, IL-6, and IL-18 are significantly elevated in patients with shock, while CCL5 was increased in milder disease. Monocyte dysregulation was specifically associated with KD-like MIS-C. Interestingly, MIS-C patients show a natural killer cell degranulation defect that is persistent after 6 months of disease presentation, suggesting it could underlie disease susceptibility. Most MIS-C had gastrointestinal involvement, and higher levels of neopterin were identified in their stools, potentially representing a biomarker of intestinal inflammation in MIS-C. Severe acute respiratory syndrome coronavirus 2-specific cellular response and neutralizing antibodies were identifiable in convalescent MIS-C patients, suggesting sustained immunity. Conclusion: Clinical characterization and comprehensive immunophenotyping of Chilean MIS-C cohort provide valuable insights in understanding immune dysregulation in MIS-C and identify relevant biomarkers of disease that could be used to predict severity and organ involvement.Publication Evaluation of the Immune Response Induced by CoronaVac 28-Day Schedule Vaccination in a Healthy Population Group(2022) Escobar, Alejandro; Reyes, Felipe; Acevedo, Mónica; Alonso, Luis; Valiente, Fernando; Soto, Ricardo; Portillo, Hugo; Gatica, Jimena; Flores, Iván; Nova, Estefanía; Barrera, Carlos; Bono, María; Vargas, Leonardo; Simon, Valeska; Leiva, Elias; Vial, Cecilia; Hormazábal, Juan; Jimena, Lina; Valdés, Daniel; Sandino, Ana; Imarai, Mónica; Acuña, ClaudioCoronaVac vaccine from Sinovac Life Science is currently being used in several countries. In Chile, the effectiveness of preventing hospitalization is higher than 80% with a vaccination schedule. However, to date, there are no data about immune response induction or specific memory. For this reason, we recruited 15 volunteers without previous suspected/diagnosed COVID-19 and with negative PCR over time to evaluate the immune response to CoronaVac 28 and 90 days after the second immunization (dpi). The CoronaVac administration induces total and neutralizing anti-spike antibodies in all vaccinated volunteers at 28 and 90 dpi. Furthermore, using ELISpot analysis to assay cellular immune responses against SARS-CoV-2 spike protein, we found an increase in IFN-gamma- and Granzyme B-producing cells in vaccinated volunteers at 28 and 90 dpi. Together, our results indicate that CoronaVac induces a robust humoral immune response and cellular immune memory of at least 90 dpi.Publication Immunization and SARS-CoV-2 Antibody Seroprevalence in a Country with High Vaccination Coverage: Lessons from Chile(2022) Aguilera, Ximena; González, Claudia; Apablaza, Mauricio; Rubilar, Paola; Icaza, Gloria; Ramírez, Muriel; Pérez, Claudia; Cortes, Lina; Núñez, Loreto; Quezada, Rubén; Castillo, Carla; Correa, Juan; Said, Macarena; Hormazábal, Juan; Vial, Cecilia; Vial, PabloChile is among the most successful nations worldwide in terms of its COVID-19 vaccine rollout. By 31 December 2021, 84.1% of the population was fully vaccinated, and 56.1% received booster doses using different COVID-19 vaccines. In this context, we aimed to estimate the prevalence of anti-SARS-CoV-2 antibodies following the infection and vaccination campaign. Using a three-stage stratified sampling, we performed a population-based cross-sectional serosurvey based on a representative sample of three Chilean cities. Selected participants were blood-sampled on-site and answered a short COVID-19 and vaccination history questionnaire using Wantai SARS-CoV-2 Ab ELISA to determine seroprevalence. We recruited 2198 individuals aged 7-93 between 5 October and 25 November 2021; 2132 individuals received COVID-19 vaccinations (97%), 67 (3.1%) received one dose, 2065 (93.9%) received two doses, and 936 received the booster jab (42.6%). Antibody seroprevalence reached 97.3%, ranging from 40.9% among those not vaccinated to 99.8% in those with booster doses (OR = 674.6, 154.8-2938.5). SARS-CoV-2 antibodies were associated with vaccination, previous COVID-19 diagnosis, age group, and city of residence. In contrast, we found no significant differences in the type of vaccine used, education, nationality, or type of health insurance. We found a seroprevalence close to 100%, primarily due to the successful vaccination program, which strongly emphasizes universal access.Item Immunization and SARS-CoV-2 antibody seroprevalence in a country with high vaccination coverage: Lessons from Chile(2022) Aguilera, Ximena; González, Claudia; Apablaza, Mauricio; Rubilar, Paola; Icaza, Gloria; Ramírez-Santana, Muriel; Pérez, Claudia; Cortés, Lina Jimena; Núñez-Franz, Loreto; Quezada-Gaete, Rubén; Castillo-Laborde, Carla; Correa, Juan; Said, Macarena; Hormazábal, Juan; Vial, Cecilia; Vial, PabloObjective: Chile is among the most successful nations worldwide in COVID-19 vaccine rollout. By December 31st, 2021, 84.1% of the population was fully vaccinated, and 56.1% received booster doses using DIFFERENT TYPES OF COVID-19 VACCINES. In this context, we aimed to estimate the anti-SARSCoV-2 antibodies following the infection and vaccination campaign. Study design: Population-based cross-sectional serosurvey based on a representative sample of the cities of Santiago, Coquimbo/La Serena, and Talca used in a previous study. Methods: We selected the participants using a three-stage stratified sampling. They were blood-sampled on-site and answered a questionnaire regarding COVID-19-associated variables and vaccination antecedents using Wantai SARS-CoV-2 Ab ELISA to determine seroprevalence. This research followed the generic protocol of World Health Organization Unity studies. Results: We recruited 2,198 individuals aged 7-93 between October 5th and November 25th, 2021. In our sample, 2,132 individuals received COVID-19 vaccinations (97%); 67 (3.1%) received one dose; 2,065 (93.9%) received the complete scheme; and 936 received the booster jab (42.6%). Antibody seroprevalence reached 97.3%, ranging from 40.9% among those not vaccinated to 99.8% in those with booster doses (OR=674.6, 154.8-2938.5). SARS-CoV-2 antibodies were associated with vaccination, previous COVID-19 diagnosis, age group, and city of residence. In contrast, we found no significant differences in the type of vaccine used, education, nationality, or type of health insurance. Conclusion: We found a seroprevalence close to 100% in the population aged seven years and older, primarily due to the successful vaccination program, which has a strong emphasis on universal access.Item SARS-CoV-2 Neutralizing Antibodies in Chile after a Vaccination Campaign with Five Different Schemes(2022) Aguilera, Ximena; Hormazábal, Juan; Vial, Cecilia; Cortés, Lina Jimena; González, Claudia; Rubilar, Paola; Apablaza, Mauricio; Ramírez-Santana, Muriel; Icaza, Gloria; Núñez-Franz, Loreto; Castillo-Laborde, Carla; Ramírez-Riffo, Carolina; Pérez, Claudia; Quezada-Gate, Rubén; Said, Macarena; Vial, PabloUsing levels of neutralizing antibodies (nAbs), we evaluate the successful Chilean SARS-CoV-2 vaccine campaign, which combines different vaccine technologies and heterologous boosters. From a population-based study performed in November 2021, we randomly selected 120 seropositive individuals, organized into six groups of positive samples (20 subjects each) according to natural infection history and the five most frequent vaccination schemes. We conclude that the booster dose, regardless of vaccine technology or natural infection, and mRNA vaccines significantly improve nAbs response.Item Seroprevalence of Natural and Acquired Immunity against the SARS-CoV-2 Virus in a Population Cohort from Two Chilean Cities, 2020–2022(2023) Núñez-Franz, Loreto; Ramírez-Santana, Muriel; Rubilar, Paola; Vial, Cecilia; Apablaza, Mauricio; González, Claudia; Said, Macarena; Olivares, Kathya; Cortés, Lina Jimena; Hormazábal, Juan; Canales, Luis; Vial, Pablo; Icaza, Gloria; Quezada-Gaete, Rubén; Aguilera, XimenaBackground: Chile has achieved the highest coverage for vaccines against the SARS-CoV-2 virus worldwide. Objective: To assess the progression of immunity (natural and acquired by vaccine) in a cohort from two Chilean cities. Methods: Individuals (n = 386) who participated in three phases of population-based serial prevalence studies were included (2020–2021 and 2022). Presence of SARS-CoV-2 antibodies was measured in serum. Data including time of vaccination and type of vaccine received were analysed with descriptive statistics. Results: Seroprevalence was 3.6% in the first round and increased to 96.9% in the second and 98.7% in the third. In the third round, 75% of individuals who had received the basal full scheme were seropositive at 180 days or more since their last dose; 98% of individuals who received one booster dose were seropositive at 180 days or more, and 100% participants who received two boosters were seropositive, regardless of time since their last dose. Participants receiving mRNA vaccines had higher seroprevalence rates over time. Conclusions: The high vaccination coverage in Chile enabled the population to maintain high levels of antibodies. Vaccination boosters are essential to maintain immunity over time, which also depends on the type of vaccine administered.