Granulocyte-macrophage colony-stimulating factor: Conductor of the wound healing orchestra?

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein and is derived from both hemopoietic and nonhemopoietic sources which exert immunomodulatory properties. Various theories have been proposed to explain why some wounds become chronic and non-healing. Generalized suppression of inflammation locally or systemically may impede the body's physiological healing response by crippling the activity of reparative cells within the wound ecosystem. Thus, highlighting the importance of promoting host-directed therapeutics with immunomodulatory properties. The temporal and spatial expression of GM-CSF and GM-CSF receptors in the integumentary system suggests that epithelial-derived GM-CSF functions in an autocrine/paracrine manner. This may positively affect wound healing physiology via local inflammatory regulation promoting macrophage survival. Although diabetes negatively affects multiple aspects of wound healing GM-CSF activation is particularly impacted. Compared to acute/healthy wounds diabetic foot ulcers (DFU) only partially activate GM-CSF activity. There is a deleterious chain of events associated with this unfortunate sequala. DFUs also have a high proportion of monocytes and an absence of activated macrophages which results in an impaired inflammatory response. This may potentially serve as a vital point for GM-CSF to act as a companion diagnostic/theragnostic modality to help modulate the inflammatory response in wound healing. Correcting macrophage immune dysfunction with exogenous GM-CSF may help restore the immune balance in the wound ecosystem and jumpstart the wound healing cascade. Thus, the recognized beneficial role of GM-CSF in immune regulation across many studies provides a rationale for the initiation of the ongoing randomized controlled trials using GM-CSF.     

NKG2D 配体在肿瘤免疫中作用新进展

NKG2D系自然杀伤性细胞(NK)和CD8+T淋巴细胞表面的激活受体。NKG2D配体分子可被细胞在应急状态和发生感染的情况下诱导表达。在肿瘤免疫监视和肿瘤免疫治疗,进行了大量的研究。NKG2D与其配体分子的结合能够激活NK细胞,并为T细胞提供协同刺激,继而激活机体体液免疫和细胞免疫机制,诱导机体的免疫杀伤作用。活化的NK细胞通过IL-15加强来自供体或受体的抗原递呈细胞(APCs)对T细胞的反应,导致机体对移植物的排斥反应。从另一面来说,经NKG2D受体激活NK细胞后,T调节细胞的数量可减小,这种调节T细胞免疫的能力下降。增加NKG2D与其配体分子的结合,可为寻找新的肿瘤免疫治疗提供研究思路。加强对这方面的研究为提高肿瘤存活期具有重要的临床价值。     

Ethanol-exposed lung fibroblasts cause airway epithelial barrier dysfunction

Background

Chronic alcohol ingestion predisposes to lung injury and disrepair during sepsis. Our previous studies outlined roles for transforming growth factor-beta 1 (TGFβ1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in epithelial barrier homeostasis and how alcohol perturbs their expression and signaling. Here we hypothesize that ethanol-exposed lung fibroblasts (LF) are a source of dysregulated TGFβ1 and GM-CSF and thereby alter airway epithelial barrier function.

Methods

Human or rat LF were cultured ± ethanol for 2 weeks and then co-cultured with human or rat airway epithelial cells (AEC) seeded on Transwell permeable supports. In selected groups, a TGFβ1 receptor type 1 (TGFβR1) inhibitor (SB431542) or a TGFβ1 neutralizing antibody was applied. Transepithelial electrical resistance (TER) was measured prior to co-culture and on day 5 of co-culture. AEC were then analyzed for the expression of selected tight junction and mesenchymal proteins, and transwell membranes were analyzed by immunofluorescence microscopy for ZO-1 expression and localization. TGFβ1 and GM-CSF levels in conditioned media from the co-cultures were quantified by ELISA.

Results

AEC co-cultured with ethanol-exposed LF (ELF) showed a significant reduction in TER and corresponding decreases in ZO-1 expression, whereas collagen type 1A1 and α-smooth muscle actin protein expression were increased. In parallel, in conditioned media from the ELF + AEC co-cultures, activated TGFβ1 levels increased and GM-CSF levels decreased. Notably, all the effects of ELF on the AEC were prevented by blocking TGFβ1 activity.

Conclusions

Prior ethanol exposure to LF induces barrier dysfunction in naive AEC in a paracrine fashion through activation of TGFβ1 signaling and suppression of GM-CSF. These experimental findings provide a potential mechanism by which chronic alcohol ingestion impairs airway epithelial integrity and renders individuals susceptible to lung injury.     

Clinical uses of recombinant haematopoietic growth factors in paediatrics

The formation of blood cells, haematopoiesis, is regulated by a family of extracellular glycosylated proteins called haematopoietic growth factors. Over the past four decades their identification, purification and cloning has led to the development of recombinant haematopoietic growth factors for medicinal use. These growth factors play a valuable role in treatment of a variety of childhood conditions, ranging from anaemia of chronic kidney disease through to rare congenital bone marrow failure syndromes. Erythropoietin and granulocyte-colony stimulating factor are the two recombinant haematopoietic growth factors in most widespread use in paediatrics and paediatricians should be aware of their indications and their side effects when managing patients. This review articles gives an overview of the major recombinant haematopoietic growth factors used in children, their indications, and their toxicities.