A Disintegrin and Metalloprotease (ADAM) 10 and ADAM17 Are Major Sheddases of T Cell Immunoglobulin and Mucin Domain 3 (Tim-3)

Abstract

Background: Membrane-bound Tim-3 regulates immune responses. Results: Soluble Tim-3 is generated by A disintegrin and metalloprotease (ADAM) 10 and ADAM17. Conclusion: ADAM proteases are involved in Tim-3 processing. Significance: Shedding of Tim-3 influences immune cell activation.

Soluble T Cell Immunoglobulin Mucin Domain 3 Is Shed from CD8 + T Cells by the Sheddase ADAM10, Is Increased in Plasma during Untreated HIV Infection, and Correlates with HIV Disease Progression

“…As previously described by Moller-Hackbarth et al (33), human Tim-3 was shown to be shed from the surfaces of monocytes by the matrix metalloproteinases ADAM10 and ADAM17, in response to the stimuli PMA and ionomycin. Tim-3 is constitutively expressed on monocytes normally and is weakly expressed on T cells, but it is upregulated on T cells in chronic viral infections (13,38).…”

“…The inclusion of the ADAM10 inhibitor resulted in a significant reduction in the levels of sTim-3 produced across all populations (P ϭ 0.0264); however, it did not completely prevent the production of sTim-3. While this could be a dosing issue with the inhibitor, ADAM17 may have contributed to Tim-3 shedding, as previously described (33). However, inhibitors specific for ADAM17 are not currently commercially available.…”

“…The use of an ADAM10 inhibitor is not ideal for these experiments, as ADAM10-mediated cleavage is not exclusive toward Tim-3; the matrix metalloproteinase is able to cleave multiple substrates (15,36,(45)(46)(47)(48)(49)(50)(51). Ideal future experiments should employ Tim-3 knockout CD8 ϩ T cells, which ectopically express a wild-type or a cleavage-deficient mutant Tim-3 (33), in order to assess the effect of Tim-3 shedding on proliferation, similar to what has been performed with LAG-3 (15).…”

“…However, this plasma Tim-3 construct is poorly characterized, and it is unclear whether this soluble Tim-3 is elevated in chronic infections such as HIV. Interestingly, Möller-Hackbarth et al described a mechanism whereby full-length membrane Tim-3 can be cleaved from the cell surface by matrix metalloproteinases ADAM10 and ADAM17, yielding a soluble Tim-3 ectodomain (IgV-like domain and mucin domain) (33). Thus, it is unclear which construct, the alternatively spliced or the membrane-cleaved sTim-3, represents the sTim-3 form found in human plasma.…”

Shedding of Endogenous Interleukin-6 Receptor (IL-6R) Is Governed by A Disintegrin and Metalloproteinase (ADAM) Proteases while a Full-length IL-6R Isoform Localizes to Circulating Microvesicles

“…BMDMs were detached using Accutase (PAA Laboratories), seeded on 6-well plates at a density of 0.5 ϫ 10 6 cells/ml, and stimulated the next day as indicated. Primary human macrophages were generated as previously described (24). Briefly, peripheral blood mononuclear cells were isolated from human blood by density gradient centrifugation and monocytes were subsequently purified with CD14 MicroBeads according to the manufacturer's instructions (Miltenyi Biotec, Bergisch-Gladbach, Germany).…”