Modulación de la magnitud, afinidad y cambio de clase de los anticuerpos mediante la activación de células Natural Killer T por distintos ligandos glicolipídico
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Date
2023
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es
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Universidad Andrés Bello
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Abstract
La activación de células B por vía T dependiente promueve la secreción de citoquinas
por parte de los linfocitos T, y la producción de anticuerpos por parte de los linfocitos B.
Esta interacción inicia la Recombinación por cambio de clase (CSR), fenómeno que
modifica las funciones efectoras de los anticuerpos sin alterar la especificidad para el
antígeno inmunizante. Un tipo no convencional de células T, conocidos como células
Natural Killer T invariantes (iNKT), puede interactuar con las células B, desencadenando
la producción de anticuerpos y CSR. La activación de las células iNKT es mediada por
ligandos glicolipídicos presentados en una molécula tipo MHC-I llamada CD1d. El
principal ligando activador de las iNKT es α-Galactosilceramida (α-GalCer), se han
descrito ligandos capaces de activar iNKT generando diferentes perfiles de citoquinas;
conocidos como análogos de α-GalCer. Este trabajo propuso el uso de liposomas (LPs)
como vehículo para la entrega de glicolípidos, en conjunto a Ovoalbúmina (OVA) como
antígeno modelo para evaluar la generación de anticuerpos OVA-específicos y el cambio
de clase en un esquema de inmunización de 60 días en ratones C57BL/6. Se propone
que los análogos de α-GalCer: AH10-7 y OCH, descritos por generar un perfil de
citoquinas tipo Th1 y Th2 respectivamente, favorecerán el cambio de clase hacia los
isotipos IgG2c e IgG1 respectivamente. Se demostró que, en una cinética de 60 días, los
tratamientos con α-GalCer y AH10-7 generaron mayores títulos de anticuerpos que los
LPs con OCH para los subtipos de IgG estudiados (IgG1, IgG2b, IgG2c e IgG3); sin
embargo, los tratamientos presentan comportamientos similares a lo largo de la cinética,
pero con magnitudes distintas. Adicionalmente, al evaluar los títulos de anticuerpos y
CSR en ratones C57BL/6 Knock-out (KO) para CD1d, no se observaron diferencias
significativas en los títulos de anticuerpos entre los ratones KO inmunizados con AH10-7
y ratones inmunizados con LP OVA, determinando que las diferencias entre estos
tratamientos son dependientes de las células iNKT. Se evaluó maduración de afinidad
para IgG1 e IgG2c y se pudo observar mayor maduración en los tratamientos con αGalCer y AH10-7. La evidencia obtenida en este trabajo demuestra que las células B al
interactuar con iNKTs activadas por ligandos glicolipídicos no modifican los tipos de
anticuerpos producidos; sin embargo, poseen la capacidad de modular la magnitud en la
que se producen los distintos isotipos.
T-dependent B cell activation promotes cytokine secretion by T lymphocytes and antibody production by B lymphocytes. This interaction initiates Class Switch Recombination (CSR), a phenomenon that modifies the effector functions of antibodies without altering specificity for the immunizing antigen. An unconventional type of T cells, known as invariant Natural Killer T (iNKT) cells, can interact with B cells, triggering the production of antibodies and CSR. Activation of iNKT cells is mediated by glycolipid ligands presented on an MHC-I-like molecule called CD1d. The main activating ligand of iNKTs is αGalactosylceramide (α-GalCer), ligands capable of activating iNKTs generating different cytokine profiles have been described; known as α-GalCer analogues. This work proposed the use of liposomes (LPs) as a vehicle for glycolipid delivery, in conjunction with Ovalbumin (OVA) as a model antigen to evaluate OVA-specific antibody generation and class switching in a 60-day immunization scheme in C57BL/6 mice. It is proposed that the α-GalCer analogues AH10-7 and OCH, described to generate a Th1- and Th2- type cytokine profile, respectively, will favor class switching towards IgG2c and IgG1 isotypes, respectively. It was demonstrated that, in a 60-day kinetics, treatments with αGalCer and AH10-7 generated higher antibody titers than LPs with OCH for the IgG subtypes studied (IgG1, IgG2b, IgG2c and IgG3); however, the treatments present similar behaviors along the kinetics, but with different magnitudes. Additionally, when evaluating antibody titers and CSRs in C57BL/6 knock-out (KO) mice for CD1d, no significant differences in antibody titers were observed between KO mice immunized with AH10-7 and mice immunized with LP OVA, determining that the differences between these treatments are iNKT cell-dependent. Affinity maturation for IgG1 and IgG2c was evaluated and greater maturation could be observed in the α-GalCer and AH10-7 treatments. The evidence obtained in this work demonstrates that B cells interacting with iNKTs activated by glycolipid ligands do not modify the types of antibodies produced; however, they have the capacity to modulate the magnitude in which the different isotypes are produced.
T-dependent B cell activation promotes cytokine secretion by T lymphocytes and antibody production by B lymphocytes. This interaction initiates Class Switch Recombination (CSR), a phenomenon that modifies the effector functions of antibodies without altering specificity for the immunizing antigen. An unconventional type of T cells, known as invariant Natural Killer T (iNKT) cells, can interact with B cells, triggering the production of antibodies and CSR. Activation of iNKT cells is mediated by glycolipid ligands presented on an MHC-I-like molecule called CD1d. The main activating ligand of iNKTs is αGalactosylceramide (α-GalCer), ligands capable of activating iNKTs generating different cytokine profiles have been described; known as α-GalCer analogues. This work proposed the use of liposomes (LPs) as a vehicle for glycolipid delivery, in conjunction with Ovalbumin (OVA) as a model antigen to evaluate OVA-specific antibody generation and class switching in a 60-day immunization scheme in C57BL/6 mice. It is proposed that the α-GalCer analogues AH10-7 and OCH, described to generate a Th1- and Th2- type cytokine profile, respectively, will favor class switching towards IgG2c and IgG1 isotypes, respectively. It was demonstrated that, in a 60-day kinetics, treatments with αGalCer and AH10-7 generated higher antibody titers than LPs with OCH for the IgG subtypes studied (IgG1, IgG2b, IgG2c and IgG3); however, the treatments present similar behaviors along the kinetics, but with different magnitudes. Additionally, when evaluating antibody titers and CSRs in C57BL/6 knock-out (KO) mice for CD1d, no significant differences in antibody titers were observed between KO mice immunized with AH10-7 and mice immunized with LP OVA, determining that the differences between these treatments are iNKT cell-dependent. Affinity maturation for IgG1 and IgG2c was evaluated and greater maturation could be observed in the α-GalCer and AH10-7 treatments. The evidence obtained in this work demonstrates that B cells interacting with iNKTs activated by glycolipid ligands do not modify the types of antibodies produced; however, they have the capacity to modulate the magnitude in which the different isotypes are produced.
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Tesis (Ingeniero en Biotecnología)
Keywords
Células Asesinas Naturales, Anticuerpos, Ligandos