Project description:Phagocytosis requires the activation of a plethora of mechanisms that include the activation of the actin cytoskeleton guided by the Arp2/3 complex. These are promoted by activators such as the Wiskott Aldrich Syndrome Protein (WASP) family members. In order to further understand the molecular mechanisms involved in the early events leading the phagocytosis of the pathogenic Mycobacterium tuberculosis, we set out to examine potential roles of miRNAs in phagocytosis using genome-wide expression profiling to identify miRNAs differentially regulated following mycobacterial infection. One of the miRNAs activated upon infection of mouse macrophages with the non-pathogenic Mycobacterium smegmatis, the widely conserved miR-142-3p, was predicted and confirmed to target the Neural-WASP (N-WASP). Upregulating of miR-142-3p in mouse macrophages inversely correlated with levels of N-WASP, upon infection with live pathogenic and non-pathogenic mycobacteria, suggesting an active role of Mycobacterium tuberculosis on the regulation of phagocytosis, at the post-transcriptional level, in host cells. The reduction of N-WASP correlated with a reduced internalization of bacteria per macrophage, independently of the phagocytosis index. Furthermore, the downregulation of WASP levels accompanied those of N-WASP, at early but not at late time points, suggesting a closely regulatory mechanism among both family members, dependent on the time frame of the phagocytosis. Additionally, upregulating of miR-142-3p promoted the change in the protein levels of another predicted and confirmed target, the Cofilin2 protein, in a phagocytosis-independent fashion. Downregulation experiments promoted aberrant morphologic phenotypes in macrophages, similar to observed by others in PBMCs of humans with Wiskott Aldrich Syndrome, suggesting the strong involvement of miR-142-3p on the regulation of the actin machinery in macrophages. Altogether these results show for the first time that miRNAs are involved in the regulation of actin-mediated phagocytosis of pathogenic bacteria and that these are direct targets of Mycobacterium tuberculosis. Expression analysis of mouse macrophage cell line J774A.1 in response to infection with Mycobacterium smegmatis mc2155 EGFP. Three biological replicates each for uninfected and infected samples.

Project description:Osteonecrosis (ON) of the femoral head (ONFH) is a devastating bone disease affecting over 20 million people worldwide. ONFH is caused by a disruption of blood supply, leading to necrotic cell death and increased inflammation. Macrophages are the key cells mediating the inflamma-tory responses in ON. It is unclear what are the dynamic phenotypes of macrophages, and what mechanisms may affect macrophage polarization and therefore the healing process. In our pre-liminary study, we found that there is an invasion of macrophages in the repair tissue during ON healing. Interestingly, in both ONFH patient and the mouse ON model, fat was co-labeled within macrophages using immunofluorescence staining, indicating phagocytosis of fat by mac-rophages. To study the effects of fat phagocytosis on macrophage phenotype, we set up an in vitro macrophage and fat co-culture system. We found that fat phagocytosis significantly de-creased M1 markers expression such as IL1β and iNOS in macrophages. Whereas the expression of M2 marker Arg1 was significantly increased with fat phagocytosis. To investigate if the polar-ization change is indeed mediated by phagocytosis, we treated the cells with Latrunculin A (LA, a phagocytosis inhibitor). LA supplement significantly reversed the polarization marker gene changes induced by fat phagocytosis. To provide an unbiased transcriptional gene analysis, we submitted the RNA for bulk RNA sequencing. Differential gene expression (DGE) analysis re-vealed top up-regulated genes were related to anti-inflammatory responses, while pro-inflammatory genes were significantly downregulated. Additionally, using the pathway en-richment and network analyses (Metascape), we confirmed that gene enriched categories related to pro-inflammatory responses were significantly downregulated in macrophages with fat phagocytosis. Finally, we validated the similar macrophage phenotype changes in vivo. To sum-marize, we discovered that fat phagocytosis occurs in both ONFH patients and the mouse ON model, which inhibits pro-inflammatory responses with increased anabolic gene expressions of macrophages. This fat phagocytosis induced macrophage phenotype is consistent with the in vivo changes shown in the ON mice model. Our study reveals a novel phagocytosis mediated macro-phage polarization mechanism in ON, which fills in our knowledge gaps of macrophage func-tions and provides new concepts in macrophage immunomodulation as a promising treatment for ON.

Project description:Phagocytosis requires the activation of a plethora of mechanisms that include the activation of the actin cytoskeleton guided by the Arp2/3 complex. These are promoted by activators such as the Wiskott Aldrich Syndrome Protein (WASP) family members. In order to further understand the molecular mechanisms involved in the early events leading the phagocytosis of the pathogenic Mycobacterium tuberculosis, we set out to examine potential roles of miRNAs in phagocytosis using genome-wide expression profiling to identify miRNAs differentially regulated following mycobacterial infection. One of the miRNAs activated upon infection of mouse macrophages with the non-pathogenic Mycobacterium smegmatis, the widely conserved miR-142-3p, was predicted and confirmed to target the Neural-WASP (N-WASP). Upregulating of miR-142-3p in mouse macrophages inversely correlated with levels of N-WASP, upon infection with live pathogenic and non-pathogenic mycobacteria, suggesting an active role of Mycobacterium tuberculosis on the regulation of phagocytosis, at the post-transcriptional level, in host cells. The reduction of N-WASP correlated with a reduced internalization of bacteria per macrophage, independently of the phagocytosis index. Furthermore, the downregulation of WASP levels accompanied those of N-WASP, at early but not at late time points, suggesting a closely regulatory mechanism among both family members, dependent on the time frame of the phagocytosis. Additionally, upregulating of miR-142-3p promoted the change in the protein levels of another predicted and confirmed target, the Cofilin2 protein, in a phagocytosis-independent fashion. Downregulation experiments promoted aberrant morphologic phenotypes in macrophages, similar to observed by others in PBMCs of humans with Wiskott Aldrich Syndrome, suggesting the strong involvement of miR-142-3p on the regulation of the actin machinery in macrophages. Altogether these results show for the first time that miRNAs are involved in the regulation of actin-mediated phagocytosis of pathogenic bacteria and that these are direct targets of Mycobacterium tuberculosis.

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	sh_5282_HYK_100918_Mac_aSA_100mM.pride.mgf.gz	Mgf
	sh_5282_HYK_100918_Mac_aSA_100mM.pride.mztab.gz	Mztab
	sh_5282_HYK_100918_Mac_aSA_100mM.raw	Raw

Dataset Information

Ozone-derived oxisterols impair lung macrophage phagocytosis via adduction of phagocytosis receptors

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Ozone-derived oxysterols impair lung macrophage phagocytosis via adduction of some phagocytosis receptors.

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