Interleukin 8

Interactions

Infiltrating T cells in IIMs are considered to be in their activated state because a vast majority of them are positive for HLA-DR Ag and LFA-1 and have a memory phenotype . In PM, infiltrating T cells express restricted TCRs with common CDR3 motifs . In vitro, CD8⁺ T cells expanded from muscle tissues of IIMs show cytotoxicity against autologous myotubes . CD4⁺ T cells obtained from normal human PBMC proliferate and secrete IFN-γ in response to allogenic myoblasts upon costimulation with anti-CD28 Ab . These results suggest the importance of T cells in the pathogenesis of IIMs. On the other hand, muscle cells of IIMs constitutively express various cell surface molecules, such as CD54, CD106, MHC class I and II Ags, and apoptosis-related molecules (i.e., CD95) . CD40 is a 50-kDa type I cell surface molecule originally identified on B cells and some epithelial carcinomas that interacts with CD40L expressed on activated T cells . In B cells, signals mediated by CD40-CD40L interaction induce B cell proliferation, differentiation, and Ig production and also rescue B cells from apoptosis . Recent studies have shown that nonlymphoid cells such as fibroblasts , epithelial cells , and endothelial cells also express CD40. In vitro, CD40 ligation results in up-regulation of several cell surface molecules and cytokine production in these cells. Several studies demonstrate that 1) muscle cells of PM/DM express CD40 and muscle-infiltrating mononuclear cells (MNCs) express CD40L; 2) CD40 is induced on cultured myoblasts by IFN-γ stimulation; and 3) CD40 ligation increases IL-8 and monocyte chemoattractant protein-1 (MCP-1) production by myoblasts. The results are discussed in terms of the implication of the roles of CD40-CD40L interaction in the immunopathogenesis of PM/DM. (1)

IL 8 Markers

Several studies on the pcr test shows the expression of the il-8

5′-GAAGAGCCCTCAGGCTGGACTG-3′; IL-8 forward (1) (this is the pcr marker)

A big study used elisa test to check the il-8 activity. For assessment of IL-8, ELISA plates were coated with anti-IL-8 mAb (1 μg/ml, mouse IgG; R&D Systems) overnight at 4°C. The plates were blocked with Tris-HCl containing 2% BSA (Sigma) for 2 h, and then rhIL-8 (R&D Systems) or diluted samples were applied. After an overnight incubation at 4°C, the plates were incubated with polyclonal rabbit anti-IL-8 Ab (2 μg/ml; Endogen, Woburn, MA) for 2 h at room temperature. Plates were then incubated with a 1/2000 dilution of alkaline phosphatase-conjugated goat anti-rabbit IgG (BioSource) for 1 h and reacted with a phosphate substrate (1.0 mg/ml of p-nitrophenylphosphate; Sigma). Absorbance was read at 405 nm (test wavelength) to 620 nm (reference wavelength). The sensitivity of the IL-8 ELISA was 15.6 pg/ml. (2). So this is another good test to check the il 8 activity.

Because the function of CD40 on myoblasts remains unknown in PM/DM, the next studies must investigate the effects of CD40 ligation on cytokine production by cultured normal myoblasts. was enhanced by CD40 ligation.

Conclusion

IL-8 and MCP-1 are cytokines that mainly induce chemotaxis of neutrophils and monocytes, respectively . Recent studies have revealed that these chemokines induce the expression of integrins such as LFA-1 on circulating leukocytes , which results in leukocyte adhesion to the vascular wall, extravasation, and infiltration of inflammatory foci. Specific Abs against IL-8 or MCP-1 have been shown to inhibit leukocyte infiltration in vivo . According to this data, it is plausible that the T cells infiltrating inflammatory foci in PM/DM stimulate the production of these chemokines by myoblasts via CD40-CD40L interaction, which further induces infiltration by MNCs around target muscle cells. This positive feedback loop may be relevant to the progression and perpetuation of inflammation in PM/DM. (4)(1)

 

Footnotes

1. Tomoko ,S. Increased CD40 Expression on Muscle Cells of Polymyositis and Dermatomyositis: Role of CD40-CD40 Ligand Interaction in IL-6, IL-8, IL-15, and Monocyte Chemoattractant Protein-1 Production¹ doi: 10.4049/​jimmunol.164.12.6593 The Journal of Immunology June 15, 2000 vol. 164 no. 12 6593-6600- http://www.jimmunol.org/content/164/12/6593.full

2. E.D. Carol^, Myositis in Children with Meningococcal Disease: A Role for Tumour Necrosis Factor-α and Interleukin-8?. Journal of Infection. Volume 44, Issue 1, January 2002, Pages 17–21. http://www.sciencedirect.com/science/article/pii/S0163445301909235

3. Shinobu F. Serum concentrations of the CXC chemokines interleukin 8 and growth-regulated oncogene-alpha are elevated in patients with systemic sclerosis. The Journal of Rheumatology vol. 30 no. 7 1524-1528. http://www.jrheum.org/content/30/7/1524.short

4. Cheng-Han W. Sjögren’s Syndrome Antigen B Acts as an Endogenous Danger Molecule to Induce Interleukin-8 Gene Expression in Polymorphonuclear Neutrophils.. Published: April 27, 2015.DOI: 10.1371/journal.pone.0125501 . http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0125501