Phenotype of Peripheral NK Cells in Latent, Active, and Meningeal Tuberculosis
José Alberto Choreño-Parra, Luis Jiménez-Álvarez, Ellis Daniela Maldonado-Díaz, Graciela Cárdenas, Luis Alejandro Fernández-López, José Luis Soto‐Hernández, Marcela Muñóz-Torrico, Gustavo Ramírez-Martínez, Alfredo Cruz‐Lagunas, Armando Vega‐López, María Lilia Domínguez‐López, Carlos Sánchez-Garibay, Parménides Guadarrama-Ortíz, Silvia Giono Cerezo, L Jiménez-Zamudio, Shabaana A. Khader, Ethel Garcı́a-Latorre, Citlaltepetl Salinas‐Lara, Joaquı́n Zúñiga
Abstract
The mechanisms underlying the immunopathology of tuberculous meningitis (TBM), the most severe clinical form of extrapulmonary tuberculosis (TB), are not understood. It is currently believed that the spread of Mycobacterium tuberculosis (Mtb) from the lung is an early event that occurs before the establishment of adaptive immunity. Hence, several innate immune mechanisms may participate in the containment of Mtb infection and prevent extrapulmonary disease manifestations. Natural killer (NK) cells participate in defensive processes that distinguish latent TB infection (LTBI) from active pulmonary TB (PTB). However, their role in TBM is unknown. Here, we performed a cross-sectional analysis of circulating NK cellCID="C008" value="s" phenotype in a prospective cohort of TBM patients ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mi>n</a:mi> <a:mo>=</a:mo> <a:mn>10</a:mn> </a:math> ) using flow cytometry. Also, we addressed the responses of memory-like NK cell subpopulations to the contact with Mtb antigens in vitro. Finally, we determined plasma levels of soluble NKG2D receptor ligands in our cohort of TBM patients by enzyme-linked immunosorbent assay (ELISA). Our comparative groups consisted of individuals with LTBI ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"> <c:mi>n</c:mi> <c:mo>=</c:mo> <c:mn>11</c:mn> </c:math> ) and PTB ( <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"> <e:mi>n</e:mi> <e:mo>=</e:mo> <e:mn>27</e:mn> </e:math> ) patients. We found that NK cells from TBM patients showed lower absolute frequencies, higher CD69 expression, and poor expansion of the CD45RO+ memory-like subpopulation upon Mtb exposure in vitro compared to LTBI individuals. In addition, a reduction in the frequency of CD56brightCD16- NK cells characterized TBM patients but not LTBI or PTB subjects. Our study expands on earlier reports about the role of NK cells in TBM showing a reduced frequency of cytokine-producing cells compared to LTBI and PTB.