A murine transmembrane tumor necrosis factor (TNF) transgene induces arthritis by cooperative p55/p75 TNF receptor signaling

Abstract

The arthritogenic activities of tumor necrosis factor (TNF) and its p55TNF-receptor (R) have been well documented in experimental animal models of arthritis, and in transgenic mice expressing wild-type or mutant transmembrane human TNF proteins in their joints. In this study we show that chronic inflammatory arthritis also develops in transgenic mice made to overexpress a mutant transmembrane from of the murine TNF protein (muTNF delta 1-12) which is known to utilize efficiently both the p55 and the p75TNFR. Cross-breeding of the transgene into a TNF knockout background did not alter development of disease. Analysis of TNF bioactivity in sera from lipopolysaccharide-stimulated mice or ex vivo macrophage cultures demonstrated that the muTNF delta 1-12 protein accumulates on the cell surface and is not processed to bioactive soluble TNF, indicating that transmembrane TNF is by itself sufficient to mediate pathogenesis of arthritis. Furthermore, using TNFR knockout mice, it is shown that development of transmembrane TNF-mediated arthritis requires the presence of the p55TNFR but is significantly delayed in the absence of the p75TNFR, suggesting a positive cooperation between the two TNFR in the arthritogenic process. These results indicate that blocking the activities of both soluble and transmembrane TNF may be required to effectively neutralize the pathogenic potential of this cytokine in arthritis.

Transmembrane TNF protects mutant mice against intracellular bacterial infections, chronic inflammation and autoimmunity

“…Generation, phenotypic and functional characterization of tmTNF mutant mice CCE (129Sv) ES cells were electroporated with a targeting vector containing a floxed neo cassette in the first intron of the murine TNF gene and the D1-12 mutation that encodes an uncleavable tmTNF protein [13,36] (Fig. 1A).…”

“…Our previous work demonstrated that ectopic over-expression of human and mouse tmTNF can induce chronic arthritis in Tg mice [13]; however, the chimeric structure of the transgenes used in these studies, the increased copy number and the specific expression patterns attained precluded conclusive observations as to whether perturbations of endogenous tmTNF supports the development of arthritis. Furthermore, combinatorial inhibition of TACE and matrix metalloproteinases was reported to be highly effective in reducing collageninduced arthritis in mice [59], suggesting a possible non-pathogenic or even protective role of tmTNF in development of the disease.…”

“…The replacement-type targeting vector (Fig. 1) was made by replacing the 724 bp BglII-SmaI fragment containing the second and third exons of TNF with a mutated 511 bp BglII-SmaI fragment carrying a deletion of the first twelve amino acids of soluble TNF (TNF D1-12 ) [13]. A pL2neo [64] gene flanked by loxP sites was inserted into the first intron of the TNF gene at the BglII site, and a PGK tk gene [65] was inserted at the 5 0 end of the targeting vector for negative selection.…”

“…Indications for a role of tmTNF in vivo have been obtained in genetically modified Tg mice. Mice overexpressing tmTNF in various organs are prone to developing arthritis [13] and Con A-induced inflammatory liver disease [14], while astrocyte-specific expression of human tmTNF triggers a chronic inflammatory and demyelinating disease of the CNS [15]. In addition, overexpressed tmTNF appears fully capable of supporting p55TNFR-dependent follicular dendritic cell (FDC) and B cell follicle development [16].…”

Immuno- and genetic therapy in autoimmune diseases

“…149 It appears that local TNF is the driving force behind the chronic inflammation as it has been elegantly shown in arthritis models in transgenic and null mice where the immune system does not play an important role. [151][152][153][154] On the other hand it has also been shown that TNF plays an important role in the maturation of B cells and the formation of germinal centers 155 in mice. A chronic arthritis model has been developed by backcrossing a TCR V␤12 transgenic onto the DBA/1 background.…”