Extracellular vesicles (EVs), including exosomes, are circulating nanoscale particles heavily implicated in cell signaling and can be isolated in vast numbers from human biofluids. Study of their ...molecular profiling and materials properties is currently underway for purposes of describing a variety of biological functions and diseases. However, the large, and as yet largely unquantified, variety of EV subpopulations differing in composition, size, and likely function necessitates characterization schemes capable of measuring single vesicles. Here we describe the first application of multispectral optical tweezers (MS-OTs) to single vesicles for molecular fingerprinting of EV subpopulations. This versatile imaging platform allows for sensitive measurement of Raman chemical composition (e.g., variation in protein, lipid, cholesterol, nucleic acids), coupled with discrimination by fluorescence markers. For exosomes isolated by ultracentrifugation, we use MS-OTs to interrogate the CD9-positive subpopulations via antibody fluorescence labeling and Raman spectra measurement. We report that the CD9-positive exosome subset exhibits reduced component concentration per vesicle and reduced chemical heterogeneity compared to the total purified EV population. We observed that specific vesicle subpopulations are present across exosomes isolated from cell culture supernatant of several clonal varieties of mesenchymal stromal cells and also from plasma and ascites isolated from human ovarian cancer patients.
Toll-like receptor-4 has been implicated in modulating ischemia-reperfusion injury in cardiac, hepatic, renal, and cerebral models. However, its role in lung ischemia-reperfusion injury is unknown. ...We hypothesize that toll-like receptor-4 has a key role in initiating the inflammatory cascade in lung ischemia-reperfusion injury.
We used toll-like receptor-4 specific short interference RNA to achieve toll-like receptor-4 knockdown in rats prior to undergoing ischemia and reperfusion. Lungs were explanted and studied for protein expression and markers of lung injury. Additional animals were evaluated for cellular uptake of toll-like receptor-4 short interference RNA. Toll-like receptor-4 short interference RNA localized to the alveolar macrophage.
In animals pretreated with toll-like receptor-4 short interference RNA, toll-like receptor-4 expression and mitogen-activated protein kinase phosphorylation were suppressed. Markers of lung injury including permeability index, myeloperoxidase content, and bronchoalveolar lavage inflammatory cell counts were all reduced with toll-like receptor-4 knockdown.
Toll-like receptor-4 is critical in the development of lung ischemia-reperfusion injury and its activation in the alveolar macrophage may be the initiating step.
Abstract Objective The requirement for toll-like receptors (TLRs) in lung ischemia reperfusion injury (LIRI) has been demonstrated but not fully characterized. Previously, we reported that TLR-4 is ...required by alveolar macrophages but not pulmonary endothelial or epithelial cells for development of LIRI. Additionally, we demonstrated differential patterns of mitogen-activated protein kinase (MAPK) activation and cytokine release in these cell types during LIRI. Here, we sought to determine whether these differences in activation responses are related to cell-specific TLR activation requirements. Methods Primary cultures of alveolar macrophages, pulmonary endothelial, and immortalized epithelial cells were pretreated with TLR-2 or TLR-4 short interference RNA (ribonucleic acid) before hypoxia and reoxygenation. Cell lysates and media were analyzed for receptor knockdown, MAPK activation, and cytokine production. Rats were pretreated with TLR-2 or TLR-4 short interference RNA before lung ischemia reperfusion and changes in lung vascular permeability were assessed. Results Knockdown of TLR-2 in alveolar macrophages did not affect MAPK phosphorylation or cytokine secretion. Conversely, TLR-2 knockdown in pulmonary endothelial and epithelial cells demonstrated significant reductions in extracellular signal-regulated kinase 1/2 activation and cytokine secretion. The lung permeability index in LIRI was decreased by TLR-4 but not TLR-2. Conclusions Differential TLR signaling and MAPK activation in response to LIRI seem to be cell specific. Short interference RNA provides an outstanding tool for examination of the underlying mechanism.
Abstract Objective Mesenchymal stromal cell–based therapies have demonstrated efficacy in treating a variety of diseases. Despite the potential benefits, there are still significant hurdles that need ...to be overcome for clinical use. We describe a cell-free–based immunotherapy approach for inducing pulmonary ischemic tolerance by using mesenchymal stromal cell–conditioned media. Methods In our well-established lung ischemia–reperfusion model, we pretreated with mesenchymal stromal cell–conditioned media 30 minutes before injury. To determine the degree of lung injury, we assessed for changes in lung vascular permeability, proinflammatory cytokines and cellular infiltrates in bronchoalveolar lavage, and histopathology. Macrophage and T-cell subsets were assessed by immunohistochemistry. Results Pretreatment with mesenchymal stromal cell–conditioned media conferred protection against lung ischemia–reperfusion injury. This protection is characterized by a significant reduction in proinflammatory cytokines, a decrease in infiltrating inflammatory cells, and increases in M2-like macrophages and regulatory T cells. Conclusions Cell-free mesenchymal stromal cell–conditioned media therapy confers pulmonary ischemic tolerance. This therapy uses paracrine factors that provide beneficial protective effects by immunomodulating the inflammatory response in resident and infiltrating cell subsets.
Abstract Objective Short interfering RNA is an effective method for target gene knockdown. However, concerns surround the design, administration, efficacy, specificity, and immunostimulatory ...potential. Although uptake by alveolar macrophages has been demonstrated, studies have not examined its use in lung ischemia–reperfusion injury. We describe the validation of short interference RNA as a novel technique for cell-specific target gene knockdown in our model of lung ischemia–reperfusion injury. Methods Dose-response experiments were performed, and 3 distinct sequences of toll-like receptor-4, toll-like receptor-2, and myeloid differentiation factor-88 short interference RNA were tested for efficacy of knockdown. Saline, lipid vector, and noncoding short interference RNA controls were used. Similar experiments were performed in primary cultures of resident pulmonary cells. Target protein knockdown was assessed by Western blot. Rat serum and cell culture media were assessed for interferon and cytokine production. Biotin labeling was used to assess short interference RNA uptake. Results Target protein expression was significantly reduced using short interference RNA. However, toll-like receptor-4 knockdown was isolated to alveolar macrophages, and biotin labeling confirmed toll-like receptor-4 short interference RNA localization to alveolar macrophages. There was significant knockdown of toll-like receptor-4 expression in cultured cells treated with toll-like receptor-4 short interference RNA. There was no significant change in interferon production after short interference RNA treatment. There was effective target protein knockdown with each sequence used. Conclusions Short interference RNA is a valid method for achieving target protein knockdown in alveolar macrophages and is an important tool in the evaluation of its role in the development of lung ischemia–reperfusion injury.
It has been presumed that antibody-mediated selective costimulatory molecule blockade of CD28 is superior to cytotoxic T lymphocyte antigen 4 (CTLA4)-Ig. This is based on the premise that ...specifically blocking CD28 allows inhibitory signals through CTLA-4 to proceed, which furthermore suppresses T-cell function.
The extracelluar domain of canine (ca)CD28 was cloned from dog peripheral blood mononuclear cells. Mice were immunized with a caCD28/murine IgG2a fusion protein. Hybridomas were produced by fusing splenocytes with mouse NSO cells and screened for caCD28 binding by ELISA. Agonistic and antagonistic activities of the monoclonal antibodies (mAb) were tested in mixed leukocyte reactions. Canine regulatory T cells were expanded using plate-bound anti-CD3 and an anti-CD28 agonist mAb.
One agonistic and seven antagonistic mAbs to canine (ca)CD28 were cloned. Binding studies indicated that an agonistic (5B8) and an antagonistic (1C6) mAb bound equally well to a caCD28/caIgG1 fusion protein and to CD28 expressed on CD4+ and CD8+ peripheral blood T cells. Antagonistic antibody blocked mixed lymphocyte reactions (MLR) in a dose-dependent manner similar to CTLA4-Ig, whereas the agonistic antibody to caCD28 enhanced MLR. The 5B8 was superior to 1C6 when either was combined with anti-caCD3 to stimulate lymphocyte proliferation. Furthermore, the agonistic mAb, 5B8, together with anti-CD3 mAb induced 100-fold proliferation of canine regulatory T cells. Relative to untreated control cells, anti-caCD28 (1C6) and CTLA4-Ig equivalently inhibited cytotoxic T lymphocyte-mediated killing of alloreactive target cells.
These studies demonstrated that mouse anti-caCD28 mAbs can be generated with agonistic or antagonistic function.
Innate and adaptive immunity both contribute to allorecognition mechanisms that drive rejection after lung transplantation. Classic allorecognition pathways have been extensively described, but there ...continues to be several unanswered questions. Exosome research appears to be a novel and potentially significant area of allorecognition research and could be the missing link that answers some existing questions. This article reviews literature that is associated with allorecognition pathways and the role of exosomes in alloreactivity.
A monoclonal antibody (mAb), P4A10, was made to the canine interleukin-2 receptor alpha chain (IL-2Rα; p55; Tac antigen; CD25) to facilitate studies of canine regulatory T-cells (Treg). By ...non-reduced Western blot, P4A10 bound to a 55
kDa protein, the size of human IL-2Rα. In flow cytometry assays, it reacted with a minor population of circulating dog CD3
+CD4
+ T-cells and the majority (>60%) of in vitro PMA-Ionomycin (PMA-IO)-activated canine CD3
+ T-cells. P4A10 recognized a hematopoietic cell population enriched for FoxP3+ cells as measured by flow cytometry. The P4A10-selected fractions of T-cells had significantly increased copy numbers of CD25, FoxP3, IL-10, and TGFβ as detected by RT-PCR (reverse transcriptase-PCR) compared to the negative fractions. The P4A10-selected cells inhibited
3H (tritiated) thymidine incorporation in a mixed leukocyte reaction (MLR) containing responders of the same origin. P4A10-selected T-cells from fresh peripheral blood mononuclear cells had less FoxP3 (
p
=
0.07) by qRT-PCR (quantitative RT-PCR) and were less suppressive (
p
=
0.01) than in vitro alloantigen-activated Treg. The mAb P4A10 is specific for canine CD25 and can be used to facilitate studies of CD25+FoxP3+ Treg in this clinically relevant large animal model.
Porous precision-templated scaffolds (PTS) with uniform, interconnected, 40 μm pores have shown favorable healing outcomes and a reduced foreign body reaction (FBR). Macrophage receptor with ...collagenous structure (MARCO) and toll-like receptors (TLRs) have been identified as key surface receptors in the initial inflammatory phase of wound healing. However, the role of MARCO and TLRs in modulating monocyte and macrophage phenotypes within PTS remains uncharacterized. In this study, we demonstrate a synergetic relationship between MARCO and TLR signaling in cells inhabiting PTS, where induction with TLR3 or TLR4 agonists to 40 μm scaffold-resident cells upregulates the transcription of MARCO. Upon deletion of MARCO, the prohealing phenotype within 40 μm PTS polarizes to a proinflammatory and profibrotic phenotype. Analysis of downstream TLR signaling shows that MARCO is required to attenuate nuclear factor kappa B (NF-κB) inflammation in 40 μm PTS by regulating the transcription of inhibitory NFKB inhibitor alpha (
) and interleukin-1 receptor-associated kinase 3 (
), primarily through a
-dependent signaling pathway. Investigation of implant outcome in the absence of MARCO demonstrates an increase in collagen deposition within the scaffold and the development of tissue fibrosis. Overall, these results further our understanding of the molecular mechanisms underlying MARCO and TLR signaling within PTS. Impact statement Monocyte and macrophage phenotypes in the foreign body reaction (FBR) are essential for the development of a proinflammatory, prohealing, or profibrotic response to implanted biomaterials. Identification of key surface receptors and signaling mechanisms that give rise to these phenotypes remain to be elucidated. In this study, we report a synergistic relationship between macrophage receptor with collagenous structure (MARCO) and toll-like receptor (TLR) signaling in scaffold-resident cells inhabiting porous precision-templated 40 μm pore scaffolds through a
-dependent pathway that promotes healing. These findings advance our understanding of the FBR and provide further evidence that suggests MARCO, TLRs, and fibrosis may be interconnected.
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