Browsing by Author "Bohmwald, Karen"

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    BCG-Based Vaccines Elicit Antigen-Specific Adaptive and Trained Immunity against SARS-CoV-2 and Andes orthohantavirus
    (2022) Soto, Jorge A.; Díaz, Fabián E.; Retamal-Díaz, Angello; Gálvez, Nicolás M. S.; Melo-González, Felipe; Piña-Iturbe, Alejandro; Ramírez, Mario A.; Bohmwald, Karen; González, Pablo A.; Bueno Ramírez, Susan; Kalergis, Alexis M.
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    Contribution of Cytokines to Tissue Damage During Human Respiratory Syncytial Virus Infection.
    (2019) Bohmwald, Karen; Gálvez, Nicolás M. S.; Canedo-Marroquín, Gisela; Pizarro-Ortega, Magdalena S.; Andrade-Parra, Catalina; Gómez-Santander, Felipe; Kalergis, Alexis M.
    The human respiratory syncytial virus (hRSV) remains one of the leading pathogens causing acute respiratory tract infections (ARTIs) in children younger than 2 years old, worldwide. Hospitalizations during the winter season due to hRSV-induced bronchiolitis and pneumonia increase every year. Despite this, there are no available vaccines to mitigate the health and economic burden caused by hRSV infection. The pathology caused by hRSV induces significant damage to the pulmonary epithelium, due to an excessive inflammatory response at the airways. Cytokines are considered essential players for the establishment and modulation of the immune and inflammatory responses, which can either be beneficial or harmful for the host. The deleterious effect observed upon hRSV infection is mainly due to tissue damage caused by immune cells recruited to the site of infection. This cellular recruitment takes place due to an altered profile of cytokines secreted by epithelial cells. As a result of inflammatory cell recruitment, the amounts of cytokines, such as IL-1, IL-6, IL-10, and CCL5 are further increased, while IL-10 and IFN-γ are decreased. However, additional studies are required to elicit the mediators directly associated with hRSV damage entirely. In addition to the detrimental induction of inflammatory mediators in the respiratory tract caused by hRSV, reports indicating alterations in the central nervous system (CNS) have been published. Indeed, elevated levels of IL-6, IL-8 (CXCL8), CCL2, and CCL4 have been reported in cerebrospinal fluid from patients with severe bronchiolitis and hRSV-associated encephalopathy. In this review article, we provide an in-depth analysis of the role of cytokines secreted upon hRSV infection and their potentially harmful contribution to tissue damage of the respiratory tract and the CNS.
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    Gestational hypothyroxinemia induces ASD-like phenotypes in behavior, proinflammatory markers, and glutamatergic protein expression in mouse offspring of both sexes
    (2024) Gonzalez-Madrid, Enrique; Rangel-Ramirez, Ma. Andreina; Opazo, Maria C.; Mendez, Luis; Bohmwald, Karen; Bueno, Susan M.; Gonzalez, Pablo A.; Kalergis, Alexis M.; Riedel, Claudia A.
    Background The prevalence of autism spectrum disorder (ASD) has significantly risen in the past three decades, prompting researchers to explore the potential contributions of environmental factors during pregnancy to ASD development. One such factor of interest is gestational hypothyroxinemia (HTX), a frequent condition in pregnancy associated with cognitive impairments in the offspring. While retrospective human studies have linked gestational HTX to autistic traits, the cellular and molecular mechanisms underlying the development of ASD-like phenotypes remain poorly understood. This study used a mouse model of gestational HTX to evaluate ASD-like phenotypes in the offspring.Methods To induce gestational HTX, pregnant mice were treated with 2-mercapto-1-methylimidazole (MMI), a thyroid hormones synthesis inhibitor, in the tap-drinking water from embryonic days (E) 10 to E14. A separate group received MMI along with a daily subcutaneous injection of T4, while the control group received regular tap water during the entire pregnancy. Female and male offspring underwent assessments for repetitive, anxious, and social behaviors from postnatal day (P) 55 to P64. On P65, mice were euthanized for the evaluation of ASD-related inflammatory markers in blood, spleen, and specific brain regions. Additionally, the expression of glutamatergic proteins (NLGN3 and HOMER1) was analyzed in the prefrontal cortex and hippocampus.Results The HTX-offspring exhibited anxious-like behavior, a subordinate state, and impaired social interactions. Subsequently, both female and male HTX-offspring displayed elevated proinflammatory cytokines in blood, including IL-1 beta, IL-6, IL-17A, and TNF-alpha, while only males showed reduced levels of IL-10. The spleen of HTX-offspring of both sexes showed increased Th17/Treg ratio and M1-like macrophages. In the prefrontal cortex and hippocampus of male HTX-offspring, elevated levels of IL-17A and reduced IL-10 were observed, accompanied by increased expression of hippocampal NLGN3 and HOMER1. All these observations were compared to those observed in the Control-offspring. Notably, the supplementation with T4 during the MMI treatment prevents the development of the observed phenotypes. Correlation analysis revealed an association between maternal T4 levels and specific ASD-like outcomes.Discussion This study validates human observations, demonstrating for the first time that gestational HTX induces ASD-like phenotypes in the offspring, highlighting the need of monitoring thyroid function during pregnancy.
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    Involvement of trained immunity during autoimmune responses
    (2023) Mora, Valentina P.; Loaiza, Ricardo A.; Soto, Jorge A.; Bohmwald, Karen; Kalergis, Alexis M.
    Recently, it has been described that innate immune cells such as monocytes, macrophages, and natural killer cells can develop a non-specific immune response induced by different stimuli, including lipopolysaccharides, Mycobacterium bovis Bacillus Calmette-Gue & PRIME;rin, and oxidized low-density lipoprotein. This non-specific immune response has been named "trained immunity," whose mechanism is essential for host defense and vaccine response, promoting better infection control. However, limited information about trained immunity in other noninfectious diseases, such as autoimmune illness, has been reported. The complexity of autoimmune pathology arises from dysfunctions in the innate and adaptive immune systems, triggering different clinical outcomes depending on the disease. Nevertheless, T and B cell function dysregulation is the most common characteristic associated with autoimmunity by promoting the escape from central and peripheral tolerance. Despite the importance of adaptative immunity to autoimmune diseases, the innate immune system also plays a prominent and understudied role in these pathologies. Accordingly, epigenetic and metabolic changes associated with innate immune cells that undergo a trained process are possible new therapeutic targets for autoimmune diseases. Even so, trained immunity can be beneficial or harmful in autoimmune diseases depending on several factors associated with the stimuli. Here, we reviewed the role of trained immunity over the innate immune system and the possible role of these changes in common autoimmune diseases, including Systemic Lupus Erythematosus, Rheumatoid Arthritis, Multiple Sclerosis, and Type 1 Diabetes.
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    Partial long-term clinical improvement after a BCG challenge in systemic lupus erythematosus-prone mice
    (2024) Mora, Valentina P.; Quero, Francisco B.; Troncoso-Bravo, Tays; Orellana, Claudia; Pereira, Patricia; Mackern-Oberti, Juan P.; Funes, Samanta C.; Soto, Jorge A.; Bohmwald, Karen; Bueno, Susan M.; Kalergis, Alexis M.
    Systemic Lupus Erythematosus (SLE) is an autoimmune disorder that causes a breakdown of immune tolerance. Current treatments mainly involve general immunosuppression, increasing the risk of infections. On the other hand, Bacillus Calmette-Gu & eacute;rin (BCG) has been investigated as a potential therapy for autoimmune diseases in recent years, prompting an ongoing investigation. This study aimed to evaluate the effect of BCG vaccination on early and late clinical presentation of SLE in a murine disease model. MRL/MPJ-Faslpr mice were immunized with BCG or treated with PBS as a control. The progress of the disease was evaluated at 27 days post-immunization (dpi) (early) and 56 dpi (late). Clinical parameters and proteinuria were monitored. Blood samples were collected for measurement of antinuclear antibodies (ANAs), anti-double-stranded DNA (anti-dsDNA), and cytokine determination was performed using ELISA. Samples collected from mice were analyzed by flow cytometry and histopathology. We observed a clinical improvement in BCG-treated mice, reduced proteinuria in the latter stages of the disease, and decreased TNF-alpha. However, BCG did not elicit significant changes in ANAs, anti-dsDNA, histopathological scores, or immune cell infiltration. BCG was only partially beneficial in an SLE mouse model, and further research is needed to determine whether the immunity induced by this vaccine can counteract lupus's autoimmune response.
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    Potential Neurocognitive Symptoms Due to Respiratory Syncytial Virus Infection
    (2021) Andrade, Catalina A.; Kalergis, Alexis; Bohmwald, Karen
    Respiratory infections are among the major public health burdens, especially during winter. Along these lines, the human respiratory syncytial virus (hRSV) is the principal viral agent causing acute lower respiratory tract infections leading to hospitalization. The pulmonary manifestations due to hRSV infection are bronchiolitis and pneumonia, where the population most affected are infants and the elderly. However, recent evidence suggests that hRSV infection can impact the mother and fetus during pregnancy. Studies have indicated that hRSV can infect different cell types from the placenta and even cross the placenta barrier and infect the fetus. In addition, it is known that infections during the gestational period can lead to severe consequences for the development of the fetus due not only to a direct viral infection but also because of maternal immune activation (MIA). Furthermore, it has been described that the development of the central nervous system (CNS) of the fetus can be affected by the inflammatory environment of the uterus caused by viral infections. Increasing evidence supports the notion that hRSV could invade the CNS and infect nervous cells, such as microglia, neurons, and astrocytes, promoting neuroinflammation. Moreover, it has been described that the hRSV infection can provoke neurological manifestations, including cognitive impairment and behavioral alterations. Here, we will review the potential effect of hRSV in brain development and the potential long-term neurological sequelae.
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    TCR Repertoire Characterization for T Cells Expanded in Response to hRSV Infection in Mice Immunized with a Recombinant BCG Vaccine
    (2020) Rey-Jurado, Emma; Bohmwald, Karen; Correa, Hernan G.; Kalergis, Alexis M.
    T cells play an essential role in the immune response against the human respiratory syncytial virus (hRSV). It has been described that both CD4(+) and CD8(+) T cells can contribute to the clearance of the virus during an infection. However, for some individuals, such an immune response can lead to an exacerbated and detrimental inflammatory response with high recruitment of neutrophils to the lungs. The receptor of most T cells is a heterodimer consisting of alpha and beta chains (alpha beta TCR) that upon antigen engagement induces the activation of these cells. The alpha beta TCR molecule displays a broad sequence diversity that defines the T cell repertoire of an individual. In our laboratory, a recombinant Bacille Calmette-Guerin (BCG) vaccine expressing the nucleoprotein (N) of hRSV (rBCG-N-hRSV) was developed. Such a vaccine induces T cells with a Th1 polarized phenotype that promote the clearance of hRSV infection without causing inflammatory lung damage. Importantly, as part of this work, the T cell receptor (TCR) repertoire of T cells expanded after hRSV infection in naive and rBCG-N-hRSV-immunized mice was characterized. A more diverse TCR repertoire was observed in the lungs from rBCG-N-hRSV-immunized as compared to unimmunized hRSV-infected mice, suggesting that vaccination with the recombinant rBCG-N-hRSV vaccine triggers the expansion of T cell populations that recognize more viral epitopes. Furthermore, differential expansion of certain TCRV beta chains was found for hRSV infection (TCRV beta(+)8.3 and TCRV beta(+)5.1,5.2) as compared to rBCG-N-hRSV vaccination (TCRV beta(+)11 and TCRV beta(+)12). Our findings contribute to better understanding the T cell response during hRSV infection, as well as the functioning of a vaccine that induces a protective T cell immunity against this virus.
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    Transient gestational hypothyroxinemia accelerates and enhances ulcerative colitis-like disorder in the male offspring
    (2024) Rivera, Juan Carlos; Opazo, Ma. Cecilia; Hernandez-Armengol, Rosario; Alvarez, Oscar; Mendoza-Leon, Maria Jose; Caamano, Esteban; Gatica, Sebastian; Bohmwald, Karen; Bueno, Susan M.; Gonzalez, Pablo A.; Neunlist, Michel; Boudin, Helene; Kalergis, Alexis M.; Riedel, Claudia A.
    IntroductionGestational hypothyroxinemia (HTX) is a condition that occurs frequently at the beginning of pregnancy, and it correlates with cognitive impairment, autism, and attentional deficit in the offspring. Evidence in animal models suggests that gestational HTX can increase the susceptibility of the offspring to develop strong inflammation in immune-mediated inflammatory diseases. Ulcerative colitis (UC) is a frequent inflammatory bowel disease with unknown causes. Therefore, the intensity of ulcerative colitis-like disorder (UCLD) and the cellular and molecular factors involved in proinflammatory or anti-inflammatory responses were analyzed in the offspring gestated in HTX (HTX-offspring) and compared with the offspring gestated in euthyroidism (Control-offspring).MethodsGestational HTX was induced by the administration of 2-mercapto-1-methylimidazole in drinking water to pregnant mice during E10-E14. The HTX-offspring were induced with UCLD by the acute administration of dextran sodium sulfate (DSS). The score of UCLD symptomatology was registered every day, and colon histopathology, immune cells, and molecular factors involved in the inflammatory or anti-inflammatory response were analyzed on day 6 of DSS treatment.ResultsThe HTX-offspring displayed earlier UCLD pathological symptoms compared with the Control-offspring. After 6 days of DSS treatment, the HTX-offspring almost doubled the score of the Control-offspring. The histopathological analyses of the colon samples showed signs of inflammation at the distal and medial colon for both the HTX-offspring and Control-offspring. However, significantly more inflammatory features were detected in the proximal colon of the HTX-offspring induced with UCLD compared with the Control-offspring induced with UCLD. Significantly reduced mRNA contents encoding for protective molecules like glutamate-cysteine ligase catalytic subunit (GCLC) and mucin-2 (MUC-2) were found in the colon of the HTX-offspring as compared with the Control-offspring. Higher percentages of Th17 lymphocytes were detected in the colon tissues of the HTX-offspring induced or not with UCLD as compared with the Control-offspring.DiscussionGestational HTX accelerates the onset and increases the intensity of UCLD in the offspring. The low expression of MUC-2 and GCLC together with high levels of Th17 Lymphocytes in the colon tissue suggests that the HTX-offspring has molecular and cellular features that favor inflammation and tissue damage. These results are important evidence to be aware of the impact of gestational HTX as a risk factor for UCLD development in offspring.