Characterization of the Antigenic Heterogeneity of Lipoarabinomannan, the Major Surface Glycolipid of Mycobacterium tuberculosis, and Complexity of Antibody Specificities toward This Antigen

Abstract

Lipoarabinomannan (LAM), the major antigenic glycolipid of Mycobacterium tuberculosis, is an important immunodiagnostic target for detecting tuberculosis (TB) infection in HIV-1–coinfected patients, and is believed to mediate a number of functions that promote infection and disease development. To probe the human humoral response against LAM during TB infection, several novel LAM-specific human mAbs were molecularly cloned from memory B cells isolated from infected patients and grown in vitro. The fine epitope specificities of these Abs, along with those of a panel of previously described murine and phage-derived LAM-specific mAbs, were mapped using binding assays against LAM Ags from several mycobacterial species and a panel of synthetic glycans and glycoconjugates that represented diverse carbohydrate structures present in LAM. Multiple reactivity patterns were seen that differed in their specificity for LAM from different species, as well as in their dependence on arabinofuranoside branching and nature of capping at the nonreducing termini. Competition studies with mAbs and soluble glycans further defined these epitope specificities and guided the design of highly sensitive immunodetection assays capable of detecting LAM in urine of TB patients, even in the absence of HIV-1 coinfection. These results highlighted the complexity of the antigenic structure of LAM and the diversity of the natural Ab response against this target. The information and novel reagents described in this study will allow further optimization of diagnostic assays for LAM and may facilitate the development of potential immunotherapeutic approaches to inhibit the functional activities of specific structural motifs in LAM.

Surface‐enhanced resonance Raman scattering for the sensitive detection of a tuberculosis biomarker in human serum

“…As before, the spectral intensities increase with the concentration of ManLAM in the sample but below the levels found for the buffer matrix in Figure . This is consistent with recent observations made by our laboratory and is in large part attributed to the labile nature of the arabinan domains of ManLAM with respect to acid hydrolysis …”

“…A list of reagents, materials, and procedures for the pretreatment of the serum samples and the SERS immunoassay have been reported in detail previously and are presented in the Supporting Information . As discussed in the Supporting Information, this work utilized a commercially available polyclonal antibody as the capture reagent.…”

“…As discussed in the Supporting Information, this work utilized a commercially available polyclonal antibody as the capture reagent. A monoclonal antibody specific to ManLAM was provided by Dr. Abraham Pinter at Rutgers University . This antibody has been shown to be particularly selective to the branched arabinan domains and capping motifs of ManLAM .…”

“…A monoclonal antibody specific to ManLAM was provided by Dr. Abraham Pinter at Rutgers University . This antibody has been shown to be particularly selective to the branched arabinan domains and capping motifs of ManLAM . ManLAM was isolated and purified by Dr. Delphi Chatterjee at Colorado State University …”

Avaliação do eixo IL-1/IL-1R na comorbidade obesidade e tuberculose

“…Além da sua capacidade de multiplicação em ambientes com baixo teor de oxigênio, sua membrana celular é rica em lipídeos. Dentre todas as moléculas, as lipomananas e lipoarabinomananas possuem alta variabilidade química estrutural (Cole et al 1998;Choudhary et al 2018) e interagem com diferentes receptores do sistema imunológico, como os receptores do tipo Toll (Toll-Like Receptors) e as lectinas tipo-c (A. K. Mishra et al 2011). Em termos simplificados, pode-se considerar que estes lipídios, proteínas e lipoglicanas fazem parte da sinalização de moléculas efetoras no processo da doença (Brennan 2003).…”