Investigating novel roles for exogenous and endogenous Galectin-3 in leukocyte recruitment to the inflamed microcirculation
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This study uses in vivo and ex vivo imaging to explore the hypothesis that
galectin-3 (Gal-3) acts as a positive regulator of leukocyte recruitment to
the inflamed microcirculation. In addition to this, due to its localisation
both within and outside the cell, the effect of exogenous as well as the
role of endogenous Gal-3 was investigated. Leukocyte recruitment in the
cremasteric microcirculation of wild-type (C57BL/6), Gal-3-/- and
CX3CR1gfp/+ mice was assessed by intravital microscopy following intrascrotal
injection of PBS, IL-1β, TNF-α or Gal-3 and intravenous
administration of anti-Ly6G to label neutrophils. Concurrently, these
responses were investigated further with the use of the parallel plate flow
chamber assay, confocal microscopy, flow cytometry, PCR analysis and
proteome profile array.
Treatment with IL-1β and TNF-α significantly reduced leukocyte rolling
velocities in WT mice, an effect that was absent in Gal-3-/- mice. These
observations were repeated in the flow chamber where Gal-3-/- leukocytes
did not capture to E-selectin and initiate downstream changes in their
activation state and cell morphology. Flow cytometric analysis showed
that Gal-3-/- neutrophils express reduced PSGL-1 in response to TNFα
and that basally both neutrophils and monocytes display reduced HPA
and PNA lectin binding – suggesting that the Gal-3-/- leukocytes have an
altered glycophenotype. Furthermore, Gal-3-/- neutrophils express
reduced CD11b basally and after TNFα treatment, though both Gal-3-/-
neutrophils and monocytes express comparable levels of L-selectin.Gal-3 did not increase ICAM-1 or E-selectin expression however,
treatment in vivo followed by confocal analysis indicated possible
increases in PECAM-1, VCAM-1 and E-selectin expression.
These data suggest the mechanisms mediating leukocyte rolling are
impaired in Gal-3 null-/- mice and support a role for Gal-3 as a positive
regulator of neutrophil and monocyte trafficking. In conclusion, this study
unveils novel biology for exogenous and endogenous Gal-3 in controlling
vascular inflammation.
Authors
Gittens, Beatrice RoseCollections
- Theses [4125]