Alternatively Activated Macrophages Differentially Express Fibronectin and Its Splice Variants and the Extracellular Matrix Protein βIG‐H3

Abstract

Alternative activation of macrophages, induced by Th 2 cytokines and glucocorticoids, is essential for the proper functioning of anti-inflammatory immune reactions. To this end, alternatively activated macrophages (aaMF) express a not yet fully unravelled set of genes including cytokines such as alternative macrophage activation-associated CC-chemokine (AMAC)-1 and pattern recognition molecules such as the scavenger receptor CD163. In order to further characterize the molecular repertoire of aaMF, differential gene expression was analyzed by combining subtractive suppression cloning and differential hybridization. We show here that aaMF induced by interleukin (IL)-4 overexpress the prototype extracellular matrix (ECM) protein fibronectin on the mRNA and protein level. This overall increase is accompanied by a shift in fibronectin splice variants from an embryonic to a mature pattern. In addition, the expression of another ECM protein, bIG-H3, is also upregulated by IL-4 in aaMF. In contrast to IL-4 and in line with its inhibitory effect on wound healing, dexamethasone exerts a strongly suppressive effect on fibronectin and bIG-H3 expression. In conclusion, overexpression of ECM proteins induced by IL-4 in macrophages suggests that aaMF may be involved in ECM deposition and tissue remodelling during the healing phase of acute inflammatory reactions and in chronic inflammatory diseases.

Alternative activation deprives macrophages of a coordinated defense program to Mycobacterium tuberculosis

“…This corresponds to the reciprocal regulation of Fcc receptors by IL-4 and IFN-c in human macrophages [28,29]. The preponderance of transcripts for the prototypic extracellular matrix protein fibronectin and platelet-derived growth factor in alternatively activated macrophages is consistent with previous observations and the involvement of IL-4-activated macrophages in extracellular matrix remodeling and fibrogenesis [30,31]. Alternatively activated macrophages were further characterized by the abundance of Comparison of the total numbers of transcripts that were significantly changed by infection revealed that alternatively activated macrophages displayed a diminished response over the time course, part of which was shared by classically activated macrophages (Fig.…”

Alternatively activated macrophages in helminth infections

“…Molecules with well-established roles in wound repair and tissue remodeling are also expressed by AAMΦs. IL-4 activation of human macrophages leads to upregulation of: extracellular matrix proteins fibronectin, tenascin-C, and βIG-H3 [42]; degradative enzymes MMP-1 and MMP-12; and the matrix cross-linking enzyme tissue transglutamase (tTG) [14]. The expression of these factors by AAMΦs was largely inhibited by dexamethasone, consistent with the inhibitory role of glucocorticoids in wound healing.…”

Human adipose tissue macrophages are of an anti-inflammatory phenotype but capable of excessive pro-inflammatory mediator production

“…M1, M2(IL-4) and M2(IL-10) macrophages were generated in vitro according to the literature [18][19][20] by incubation of PBMs in 1000 U/ml IFN-g, 10 ng/ml IL-4 and 10 ng/ml IL-10 (all R&D Systems, Minneapolis, MN, USA), respectively, for 5-6 days in culture medium (RPMI 1640 supplemented with 2 mM L-glutamine, 50 mg/ml streptomycin, 50 U/ml penicillin (all Invitrogen, Carlsbad, CA, USA) and 10% fetal calf serum (Hyclone; Logan, UT, USA)). Before further analyses, cells were treated with liberase and DNAse as described for SVC isolation to allow comparisons with ATderived cells.…”