Ability Of Phagocytic Cells Research Articles

Myeloid-specific knockout of SHP2 regulates PI3K/PLCγ signaling pathway to protect against early myocardial infarction injury.

To study the effects of myeloid-specific knockout of SHP2 on early myocardial infarction and explore its molecular mechanism. The model of myocardial infarction was established by using SHP2 in myeloid-specific knockout mice, and the effect of SHP2MAC-KO on myocardial function was detected by echocardiography. The effects of SHP2 on myocardial infarct size in myeloid-specific knockout mice was examined by TTC assay and Masson staining. Then, the detection of apoptosis was performed using TUNEL staining and inflammatory cell infiltration was observed using immunohistochemical staining. Moreover, macrophages in mouse hearts were selected by Flow Cytometry and treated with PI3K inhibitors respectively. Western blotting was then used to detect protein expression of p-SHP2 and PI3K/PLCγ signaling pathway. The phagocytic ability of cells was detected by endocytosis test, and the expression of inflammatory cytokines was detected by ELISA. Specific knockout of SHP2 in mice with myocardial infarction can improve the cardiac function, decrease infarct size, and reduce apoptosis as well as inflammatory cell infiltration. It also can mediate the PI3K/PLCγ signaling pathway in macrophages, which in turn enhances the endocytosis of macrophages and reduces the expression of inflammatory cytokines in macrophages. Myeloid-specific knockout of SHP2 regulates PI3K/PLCγ signaling pathway to protect against early myocardial infarction injury.

Endogenous expression of Notch pathway molecules in human trabecular meshwork cells

PurposeCells in the trabecular meshwork sense and respond to a myriad of physical forces through a process known as mechanotransduction. Whilst the effect of substratum stiffness or stretch on TM cells have been investigated in the context of transforming growth factor (TGF-β), Wnt and YAP/TAZ pathways, the role of Notch signaling, an evolutionarily conserved pathway, recently implicated in mechanotransduction, has not been investigated in trabecular meshwork (TM) cells. Here, we compare the endogenous expression of Notch pathway molecules in TM cells from glaucomatous and non-glaucomatous donors, segmental flow regions, and when subjected to cyclical strain, or grown on hydrogels of varying rigidity. MethodsPrimary TM from glaucomatous (GTM), non-glaucomatous (NTM) donors, and from segmental flow regions [high flow (HF), low flow (LF)], were utilized between passages 2–6. Cells were (i) plated on tissue culture plastic, (ii) subjected to cyclical strain (6 h and 24 h), or (iii) cultured on 3 kPa and 80 kPa hydrogels. mRNA levels of Notch receptors/ligands/effectors in the TM cells was determined by qRT-PCR. Phagocytosis was determined as a function of substratum stiffness in NTM-HF/LF cells in the presence or absence of 100 nM Dexamethasone treatment. ResultsInnate expression of Notch pathway genes were significantly overexpressed in GTM cells with no discernible differences observed between HF/LF cells in either NTM or GTM cells cultured on plastic substrates. With 6 h of cyclical strain, a subset of Notch pathway genes presented with altered expression. Expression of Notch receptors/ligands/receptors/inhibitors progressively declined with increasing stiffness and this correlated with phagocytic ability of NTM cells. Dexamethasone treatment decreased phagocytosis regardless of stiffness or cells isolated from segmental outflow regions. ConclusionsWe demonstrate here that the Notch expression in cultured TM cells differ intrinsically between GTM vs NTM, and by substratum cues (cyclical strain and stiffness). Of import, the most apparent differences in gene expression were observed as a function of substratum stiffness which closely followed phagocytic ability of cells. Interestingly, on soft substrates (mimicking normal TM stiffness) Notch expression and phagocytosis was highest, while both expression and phagocytosis was significantly lower on stiffer substrates (mimicking glaucomatous stiffness) regardless of DEX treatment. Such context dependent changes suggest Notch pathway may play differing roles in disease vs homeostasis. Studies focused on understanding the mechanistic role of Notch (if any) in outflow homeostasis are thus warranted.

A mouse ear skin model to study the dynamics of innate immune responses against Staphylococcus aureus biofilms

BackgroundStaphylococcus aureus is a human pathogen that is a common cause of nosocomial infections and infections on indwelling medical devices, mainly due to its ability to shift between the planktonic and the biofilm/sessile lifestyle. Biofilm infections present a serious problem in human medicine as they often lead to bacterial persistence and thus to chronic infections. The immune responses elicited by biofilms have been described as specific and ineffective. In the few experiments performed in vivo, the importance of neutrophils and macrophages as a first line of defence against biofilm infections was clearly established. However, the bilateral interactions between biofilms and myeloid cells remain poorly studied and analysis of the dynamic processes at the cellular level in tissues inoculated with biofilm bacteria is still an unexplored field. It is urgent, therefore, to develop biologically sound experimental approaches in vivo designed to extract specific immune signatures from the planktonic and biofilm forms of bacteria.ResultsWe propose an in vivo transgenic mouse model, used in conjunction with intravital confocal microscopy to study the dynamics of host inflammatory responses to bacteria. Culture conditions were created to prepare calibrated inocula of fluorescent planktonic and biofilm forms of bacteria. A confocal imaging acquisition and analysis protocol was then drawn up to study the recruitment of innate immune cells in the skin of LysM-EGFP transgenic mice. Using the mouse ear pinna model, we showed that inflammatory responses to S. aureus can be quantified over time and that the dynamics of innate immune cells after injection of either the planktonic or biofilm form can be characterized. First results showed that the ability of phagocytic cells to infiltrate the injection site and their motility is not the same in planktonic and biofilm forms of bacteria despite the cells being considerably recruited in both cases.ConclusionWe developed a mouse model of infection to compare the dynamics of the inflammatory responses to planktonic and biofilm bacteria at the tissue and cellular levels. The mouse ear pinna model is a powerful imaging system to analyse the mechanisms of biofilm tolerance to immune attacks.

Successful hepatectomy for hepatic abscess with chronic granulomatous disease: a case report

BackgroundChronic granulomatous disease (CGD), a rare inherited disorder, is characterized by impaired ability of phagocytic cells to kill certain bacteria and fungi. Although liver abscess is a common manifestation of CGD, its optimal management in these patients is unknown. Here, we present a case of successful hepatectomy for hepatic abscess in a patient with CGD.Case presentationAn adolescent patient with previously diagnosed CGD presented to the pediatrics department of our institution with fever. Blood tests showed high concentrations of inflammatory markers. A computed tomography (CT) scan showed a multilocular mass measuring 52 mm × 34 mm in hepatic segment 4 (S4). Blood cultures were negative. Despite administration of antibiotics and γ-globulin, his fever and high concentrations of inflammatory markers persisted and the mass did not change on CT scan images. Because the medications had proved ineffective and percutaneous drainage would have been difficult because of the honeycombing in the abscess, we performed hepatic S4a + S5 anatomic resection and cholecystectomy. Culture of the excised specimen was negative. The patient’s postoperative course was uneventful. On day 62, CT showed no abscess around the resection stump. On day 81, he was transferred to undergo bone marrow transplantation.ConclusionsSurgical treatment for hepatic abscess can be effective when medical treatment has failed.

Nanoparticle interactions with zinc and iron: Implications for toxicology and inflammation

Background Particulate air pollution (PM 10) consists of a mixture of components, including nanoparticles and metals. Studies from our laboratory have demonstrated that transition metals can potentiate the ability of nanoparticles to induce lung inflammation and that the zinc content of PM 10 was largely responsible for their potential to induce inflammation. These results are also relevant to zinc-containing engineered nanoparticles. Objectives To investigate the potential of ZnCl 2 and FeCl 3 to interact with nanoparticle carbon black in cell-free and biological systems to generate ROS, express pro-inflammatory mediators and cytotoxic ability. Methods ROS production was examined using DCFH-DA. J774 cells were treated for 4 h with 14 nm CB and/or ZnCl 2 before measuring TNF-α by ELISA. Cytoskeletal changes were investigated using confocal microscopy. Flow cytometry was used to examine apoptotic/necrotic cells and phagocytic ability. Results In a cell-free system the particles generated significant ROS, whereas ZnCl 2 did not. Treatment of cells with 100 μM ZnCl 2, but not FeCl 3, increased TNF-α. Treatment with 14 nm CB alone induced TNF-α, which was synergistically enhanced by ZnCl 2. No interactions were observed in cells treated with 14 nm CB and FeCl 3. Cytoskeletal changes were observed with increasing concentrations of ZnCl 2. These results were confirmed by flow cytometry indicating that ZnCl 2 induced markers of apoptosis and necrosis. The phagocytic ability of cells was also significantly decreased. Nanoparticle carbon black alone did not induce changes in apoptosis/necrosis or the phagocytosis activity of the cells. Conclusion Despite an inability to induce ROS production, ZnCl 2 stimulated TNF-α production which was synergistically enhanced by 14 nm carbon black. The ability of zinc to induce morphological changes and cell death was not altered by nanoparticle treatment.

Excessive apoptosis of guinea pig colonocytes may lead to an imbalance between phagocytosis and degradation in vivo.

The success or failure of the clearance of apoptotic cell remains depends on the ability of phagocytic cells to recognize, phagocytoze, and digest these remains prior to their lysis, which would cause tissue inflammation. We have recently shown that, after mass-induced apoptosis of guinea pig colonocytes in vivo, phagocytosis by resident macrophages, although efficient, does not prevent a pre-inflammatory response of the mucosa. The present study has investigated the cause(s) of this clearance failure. Immunohistochemistry and transmission electron microscopy were applied. Antibodies directed against the epithelial plasma membrane protein E-cadherin, the lysosomal membrane protein LAMP-1, and the lysosomal matrix protease cathepsin-D were used. The results revealed that: (1) anti-E-cadherin labeled the membrane of epithelial apoptotic bodies internalized in macrophages, (2) double and triple labeling demonstrated that the anti-LAMP-1 and anti-cathepsin-D antibodies recognized and were co-localized in lysosomes and/or phagolysosomes in macrophages but left E-cadherin-positive structures unlabeled, (3) the more numerous were the E-cadherin-positive inclusions in macrophages, the smaller was the number of those that stained positive for lysosomal markers. In parallel with electron microscopy, these findings showed that not all apoptotic bodies phagocytozed by macrophages were subsequently digested, suggesting that the phagocytotic ability of these cells was not matched by their digestive capability.

Variations in Expression of Markers by Populations of Adherent Cells from Trypanosoma cruzi‐Infected Mice1

The kinetics of differentiation and maturation of phagocytic cells during the acute and chronic stages of experimental Chagas' disease was examined by monitoring changes in expression of peroxidase (PO), nonspecific esterase (NSE), C3b receptors (CR), Fc receptors (FcR), and phagocytic ability of cells in the blood, spleen, and peritoneal cavity. The significant changes recorded in the blood were: marked increases in the percentages of CR- and FcR-positive adherent cells during both the acute and chronic phase; Ia-positive cells increased two-fold in the acute period and remained elevated in the chronic stage. In the spleen, the major alterations recorded during both the acute and chronic stages were: two- to three-fold increases in the percentages of NSE- and PO-positive adherent cells and three- to four-fold increases in the proportions of CR- and FcR-positive cells. In addition, Ia-positive cells increased from 70% to approximately 90% of the adherent cell population. In the peritoneal cavity, a two- to four-fold elevation in the percentages of both PO- and NSE-positive cells was observed. The number of Ia-positive cells increased from 10% before infection to 85-90% during the acute phase and to 96-98% during the chronic period. All of the changes described above occurred in the absence of noticeable increases in phagocytic ability except for an elevation in the percentage of circulating latex-ingesting cells seen during chronicity. These results indicate that infection with Trypanosoma cruzi alters the pathways of differentiation of cells of the mononuclear phagocyte lineage.