Journal: Molecular Neurobiology

Article Title: Neural Expression of IL-16 Mediates Neuropathic Pain after Sciatic Injury in Mice

doi: 10.1007/s12035-026-06280-2

Figure Lengend Snippet: Expression of IL-16 in axons and Schwann cells of injured sciatic nerves. Lack of effect of neutrophil depletion on thermal hyperalgesia and IL-16 labelling in nerves. ( a1 – a4 ) Representative examples of confocal images of cross sections of injured sciatic nerves labelled with DAPI (blue, a1 ), IL-16 (green, a2 ) and the neural marker βIII-tubulin (red, a3 ). The merged image shows the colocalization of IL-16 and βIII-tubulin (yellow, a4 ), and higher-magnification images of the yellow, blue and red boxes are shown in a5 ). The yellow box shows an axon double-positive for IL-16 and βIII-tubulin (yellow). The blue box contains two small-diameter axons, one of them double-positive for IL-16 and βIII-tubulin (yellow) and the other only positive for βIII-tubulin (red). The red box indicates a βIII-tubulin-positive axon surrounded by IL-16 immunoreactivity with a shape compatible with a Schwann cell (green). ( b1 – b4 ) Confocal images corresponding to cross sections in injured sciatic nerves labelled with DAPI (blue, b1 ), IL-16 (green, b2 ) and the Schwann cell marker S100β (red, b3 ). The merged image shows the colocalization of IL-16 and S100β (yellow, b4 ). Higher-magnification images of the cell contained in the red box appear in b5 , when labelled with IL-16 (green, left hand side), S100β (red, middle image) and the merged image with DAPI (yellow, right hand side). ( c1 ) Representative merged image of IL-16, Ly6G and DAPI immunofluorescence in a longitudinal section coming from an injured nerve showing the presence of some neutrophils in a square remarked by a white dashed line. ( c2 – c5 ) Higher-magnification images of cells contained in the box, when labelled with DAPI (blue, c2 ), IL-16 (green, c3 ), Ly6G (red, c4 ) and the merged image showing the colocalization of IL-16 + and Ly6G + cells (yellow, c5 ). ( d ) Schematic representation of the experimental procedure used to evaluate the functional effect of an anti-IL-16 antibody in neutrophil-depleted mice submitted to sciatic nerve ligation 2 days before. ( e ) Decreased withdrawal latencies are shown in neutrophil-depleted mice 2 days after nerve ligation. The s.c. administration of the anti-IL-16 antibody (10 µg/kg) reversed this thermal hyperalgesia measured by the unilateral hot plate test 1 h later. Means and their corresponding standard errors are represented, •• p < 0.01 compared with the contralateral paw; ** p < 0.01 compared with values obtained in injured mice treated with IgG2bκ, two-way ANOVA followed by Tukey’s test. ( f ) Representative immunofluorescent merged image of IL-16 + traits (green) and DAPI nuclear staining (blue) in a longitudinal section of the ligated sciatic nerve from a neutrophil-depleted mouse

Article Snippet: Sections were simultaneously incubated overnight at 4 °C in a humidified chamber with the rabbit polyclonal anti-IL-16 antibody (1:100) and a rat monoclonal anti-Ly6G antibody (1:200; Bio X Cell, BE0075-1).

Techniques: Expressing, Confocal, Marker, Immunofluorescence, Functional Assay, Ligation, Hot Plate Test, Staining