TGF-β in the Secretome of Irradiated Peripheral Blood Mononuclear Cells Supports In Vitro Osteoclastogenesis

Abstract

Osteoclastogenesis required for bone remodeling is also a key pathologic mechanism of inflammatory osteolysis being controlled by paracrine factors released from dying cells. The secretome of irradiated, dying peripheral blood mononuclear cells (PBMCs) has a major impact on the differentiation of myeloid cells into dendritic cells, and macrophage polarization. The impact on osteoclastogenesis, however, has not been reported. For this aim, we used murine bone marrow macrophages exposed to RANKL and M-CSF to initiate osteoclastogenesis, with and without the secretome obtained from γ-irradiated PBMCs. We reported that the secretome significantly enhanced in vitro osteoclastogenesis as determined by means of histochemical staining of the tartrate-resistant acid phosphatase (TRAP), as well as the expression of the respective target genes, including TRAP and cathepsin K. Considering that TGF-β enhanced osteoclastogenesis, we confirmed the TGF-β activity in the secretome with a bioassay that was based on the increased expression of IL11 in fibroblasts. Neutralizing TGF-β by an antibody decreased the ability of the secretome to support osteoclastogenesis. These findings suggested that TGF-β released by irradiated PBMCs could enhance the process of osteoclastogenesis in vitro.

The effect of paracrine factors released by irradiated peripheral blood mononuclear cells on neutrophil extracellular trap formation

“…The tissue regenerative and anti-inflammatory action spectrum of PBMCsec is multifaceted (33,35,38,41,47,49,50), and most of its beneficial effects have been shown to require the interplay of several components of the secretome (34,63) . Indeed, we also found that NET formation was only fully inhibited when neutrophils Therefore, it is conceivable that the partial inhibition of NET formation observed by PBMCsec-lipids may be explained by the variety of resolvins found in PBMCsec (41).…”

“…The observed tissue-regenerative effect of PBMCsec is based on a complex interplay of various biologically active agents produced and released by stressed PBMCs (34,35,37). The broad action spectrum of PBMCsec has been intensively investigated and revealed promising treatment opportunities, where anti-inflammatory (49,50), anti-microbial (36), tissue-regenerative (35), pro-angiogenic (34,51) and vasodilatory (40) properties are important.…”

The secretome of irradiated peripheral blood mononuclear cells attenuates activation of mast cells and basophils

“… 24 Furthermore, potent anti-inflammatory actions of PBMCsec have been observed in myocarditis 25 and contact hypersensitivity. 26 Functional studies revealed a broad action spectrum of PBMCsec, which covers anti-inflammatory features, 27 , 28 tissue-regenerative, 29 anti-microbial, 30 vasodilatory, 31 and pro-angiogenic 24 , 32 properties. Though strong immunomodulatory effects have been attributed to PBMCsec, 25 potential anti-inflammatory actions in IgE-mediated allergic reactions have not been elucidated so far.…”

Secretome of Stressed Peripheral Blood Mononuclear Cells Alters Transcriptome Signature in Heart, Liver, and Spleen after an Experimental Acute Myocardial Infarction: An In Silico Analysis

“…In-depth analyses identified numerous biologically active constituents present in the secretome obtained from γ-irradiated PBMCs (PBMCsec), such as proteins, extracellular vesicles, and lipids [ 20 , 21 , 22 , 23 , 24 ]. Functional studies unveiled a diverse action spectrum of these pleiotropic substances, including anti-inflammatory [ 23 , 25 ], tissue-regenerative [ 20 ], anti-microbial [ 26 ], vasodilatory [ 27 ], and pro-angiogenic [ 28 ] properties. During the course of seminal research works, the therapeutic efficacy of the PBMCsec was successfully demonstrated in various ischemic indications, including AMI [ 22 , 29 ], chronic ischemic left ventricular dysfunction [ 30 ], and cerebral ischemia [ 31 ], but also numerous other conditions, such as autoimmune myocarditis [ 32 ], acute spinal cord injury [ 33 ], burn injury [ 34 ], diabetic wounds [ 24 ], and dendritic cell-mediated skin inflammation [ 21 ].…”