ABSTRACT
Chronic immune activation despite long-term therapy poses an obstacle to immune recovery in HIV infection. The role of antigen presenting cells (APCs) in chronic immune activation during HIV infection remains to be fully determined. APCs, the frontline of immune defense against pathogens, are capable of distinguishing between pathogens and non-pathogenic, commensal bacteria. We hypothesized that HIV infection induces dysfunction in APC immune recognition and response to some commensal bacteria and that this may promote chronic immune activation. Therefore we examined APC inflammatory cytokine responses to commensal lactobacilli. We found that APCs from HIV-infected patients produced an enhanced inflammatory response to Lactobacillus plantarum WCFS1 as compared to APCs from healthy, HIV-negative controls. Increased APC expression of TLR2 and CD36, signaling through p38-MAPK, and decreased expression of MAP kinase phosphatase-1 (MKP-1) in HIV infection was associated with this heightened immune response. Our findings suggest that chronic HIV infection enhances the responsiveness of APCs to commensal lactobacilli, a mechanism that may partly contribute to chronic immune activation.
Subject(s)
Antigen-Presenting Cells/immunology , HIV Infections/blood , HIV Infections/immunology , Lactobacillus/immunology , Adult , Aged , CD36 Antigens/metabolism , Chronic Disease , Cohort Studies , Dendritic Cells/metabolism , Female , HIV Infections/enzymology , HIV Infections/microbiology , Humans , Immunity/immunology , Inflammation/blood , Inflammation/immunology , Inflammation/pathology , MAP Kinase Signaling System , Male , Middle Aged , Monocytes/metabolism , Phosphorylation , Receptors, Immunologic/metabolism , Toll-Like Receptor 2/metabolism , Young Adult , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
Polyol-responsive monoclonal antibodies (PR-mAbs) are useful for the purification of proteins in an easy, one step immunoaffinity step. These antibodies allow for gentle purification of proteins and protein complexes using a combination of a low molecular weight polyhydroxylated compound (polyol) and a nonchaotrophic salt in the eluting buffer. mAb 8RB13 has been characterized as one of these PR-mAbs and has been used to purify RNA polymerase from five species of bacteria. Here the epitope for 8RB13 has been identified as PEEKLLRAIFGEKAS, a sequence that is highly conserved in the ß-subunit of bacterial RNA polymerase. This sequence is located in the "beta-flap" domain of RNA polymerase (and essentially comprises the "flap-tip helix"), an important binding site for sigma70. This location explains why only the core RNAP is purified using this mAb. This amino acid sequence has been developed into an epitope tag that can be used to purify a target protein from either bacterial or eukaryotic cells when genetically fused to a protein of interest.
Subject(s)
Antibodies, Monoclonal/immunology , Bacterial Proteins/isolation & purification , Chromatography, Affinity/methods , DNA-Directed RNA Polymerases/isolation & purification , Immunosorbent Techniques , Amino Acid Sequence , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/genetics , Antibodies, Monoclonal/metabolism , Bacterial Proteins/immunology , Bacterial Proteins/metabolism , DNA-Directed RNA Polymerases/immunology , DNA-Directed RNA Polymerases/metabolism , Epitope Mapping , Epitopes , Escherichia coli , Green Fluorescent Proteins/isolation & purification , Green Fluorescent Proteins/metabolism , HEK293 Cells , Humans , Luminescent Proteins/isolation & purification , Luminescent Proteins/metabolism , Molecular Sequence Data , Polymers , Recombinant Fusion Proteins/immunology , Recombinant Fusion Proteins/isolation & purification , Recombinant Fusion Proteins/metabolism , Sequence AlignmentABSTRACT
Multipotent mesenchymal stromal cells (MSCs) home to damaged tissue by processes partly regulated by integrins. Integrin subunits expressed by MSCs were identified by flow cytometry (FC), immunocytochemistry (IC), and a panel of integrin-binding antibodies. In subconfluent cultures, over 80% of MSCs expressed integrin subunits beta1, beta2, and alpha3, 20%-55% expressed alpha1, alpha2, alpha4, alpha5, alpha6, and alphaV, and about 10% expressed beta3 when assayed by FC. None of the cells expressed significant levels of 13 other integrins as assayed by FC, but seven of the 13 integrins were detected by IC: beta5, alpha7, alpha8, alpha9, alpha11, alphaX, and alphaD. Expression of some integrins changed with MSC confluency: integrins beta3, alpha1, alpha3, alpha5, and alphaV increased, and alpha6 decreased. Furthermore, alpha4 was the only integrin to vary among preparations of MSCs from different donors. The results resolved some discrepancies in the literature concerning integrin expression by MSCs. We also investigated the role of specific integrins in MSC adhesion to endothelial cells (ECs) from the pulmonary artery (HPAEC), cardiac-derived microvasculature (HMVEC-C), and umbilical veins (HUVEC). In experiments with blocking antibodies to beta integrins, anti-beta5 reduced MSC adhesion to all types of ECs, anti-beta1 to both HUVEC and HPAEC, anti-beta3 to HUVEC, and anti-beta2 to HMVEC-C. With blocking antibodies to alpha integrins, anti-alphaX reduced adhesion to HPAEC and HMVEC-C, anti-alphaV to HPAEC, and both anti-alpha7 and anti-alphaD to HMVEC-C. Thus, MSCs use diverse integrins to adhere to EC from various blood vessels in vitro.
