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| Author(s): |
Paulo José Basso
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI) |
| Defense date: | 2021-03-08 |
| Examining board members: |
Niels Olsen Saraiva Câmara;
Maria Bellio;
Ana Flavia Popi;
João Santana da Silva
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| Advisor: | Niels Olsen Saraiva Câmara; Rafael Ribeiro Almeida |
| Abstract | |
Its recent the concept of cells being able to modify their metabolic profile to perform specific functions under influence from environment. To this end, metabolic sensors such as AMPK and HIF-1 converge intra and extracellular signals to coordinate the cell fate, regulating cell energy, activation, growing and differentiation. However, the role of metabolic sensors on B cells has not been assessed. Our hypothesis was that modulation of AMPK and/or HIF-1α activity would change the metabolism, function, longevity and differentiation of B cells into antibody-secreting cells (ASCs) being able to modify the course of inflammatory diseases. Our results showed that LPS-stimulated AMPK-deficient B (AMPKB) cells increased glucose uptake, glycolytic activity and activation status by enhancing the expression of costimulatory molecules (CD40 and CD86), cytokine synthesis (IL-10 and IL-6) and antibody secretion by ASCs. In contrast to that, B cells treated with AMPK agonist metformin or B cells deficient in mTORC1, a protein negatively regulated by AMPK, decreased costimulatory molecule expression, cytokine synthesis and aerobic glycolysis. AMPKB cells also decreased mitochondrial mass, activity and respiratory capacity. In addition, AMPKB animals subjected to DSS-induced acute colitis had a significant improve in their clinical signs but had a worst prognosis in DSS-induced chronic colitis. Acute immunization experiments showed that AMPK-deficient B cells increased antibody secretion but decreased ULK1 expression, impairing the mitophagy process. As consequence, B cells increased ROS production and lipid peroxidation after recall antibody response decreasing both cell frequency and antibody synthesis. Using an in vitro -induced germinal center B cell culture system, it was found that hypoxia hindered class switching recombination (CSR) to IgG but it did not affect plasma cell differentiation. Moreover, HIF-1α overexpression or deletion decreased or increased, respectively, CSR to IgG1. At last, HIF-1α deletion in B cells eight weeks after being adoptively transferred into Rag2-/- recipient mice immunized with NP-KLH decreased the frequency of long-lived plasma cells in bone marrow and spleen. Altogether, AMPK coordinates the activation, metabolism, mitochondrial homeostasis and antibody production in B cells. AMPK in B cells is also a potential target to treat acute inflammatory diseases. HIF-1α, in turn, is a key regulator to long lived plasma cell maintenance but impairs CSR to IgG1. (AU) | |
| FAPESP's process: | 15/26682-6 - Evaluation of mTOR on energy metabolism and activation of B cells during experimental intestinal inflammation |
| Grantee: | Paulo José Basso |
| Support Opportunities: | Scholarships in Brazil - Doctorate |