Background and aims: Cytokine production by endothelial cells, has, for practical reasons, been chiefly studied in human umbilical vein endothelial cells (HUVEC) but, because tissue-specific differences apparently exist, the role of human intestinal microvascular endothelial cells (HIMEC) as a source of mucosal cytokines was also assessed.
Methods: The expression of cytokine transcripts in HIMEC was screened by means of reverse transcription polymerase chain reaction (RT-PCR) and compared with cytokine profiles of HUVEC. Production of cytokines was investigated by bioassay and enzyme linked immunosorbent assay (ELISA).
Results: In the basal unstimulated state, HIMEC and HUVEC cultures contained detectable mRNA for interleukin (IL)-3, IL-7, IL-8, IL-11, IL-14, IL-15, tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and granulocytemacrophage colony stimulating factor (GM-CSF). However, message was undetectable for IL-2, IL-4, IL-5, IL-9, IL-10, IL-12p40, IL-13, and interferon (IFN)-gamma in the resting as well as the stimulated state. Stimulation of HIMEC and HUVEC with recombinant human (rh) IL-1 beta or rhTNF-alpha induced cell associated bioactive IL-1 alpha but not IL-1 beta, as well as enhanced secretion of both IL-6 and IL-8. Furthermore, transcript levels for GM-CSF and TNF-alpha were enhanced by rhIL-1 beta or rhTNF-alpha in both cell types. Supernatants from Th1-like or Th0-like gluten reactive intestinal T cell clones derived from patients with coeliac disease elicited cytokine profiles in both HIMEC and HUVEC similar to those revealed after rhIL-1 beta or rhTNF-alpha stimulation.
Conclusions: These data demonstrate that the intestinal microvascular endothelium may contribute to the cytokine network of the intestinal mucosa with the ability to respond to locally generated cytokines and to produce potent inflammatory mediators.