IT administration of the PKCδ inhibitor attenuates sepsis-induced expression of the adhesion molecules ICAM-1 and VCAM-1 in the pulmonary endothelium. A: Immunohistochemical detection of ICAM-1 in representative lung tissue sections from 24 hours after surgery (minimum of n = 3 animals per group). After primary antibody incubation, ICAM-1 was visualized using HRP-conjugated secondary antibodies and the peroxidase substrate chromogen AEC, which produces a red reaction product. In the sham-surgery group, ICAM-1 staining was barely detectable, and lung architecture was normal. In the CLP+PBS group, robust ICAM-1 localization was observed throughout the distal lung tissue and in the large arteries accompanying the bronchial airways. In the CLP+PKCδ-TAT group, ICAM-1 staining was reduced to near the levels with sham surgery. B: Immunohistochemical detection of VCAM-1 in representative lung tissue sections from 24 hours after surgery (minimum of n = 3 animals per group). After primary antibody incubation, VCAM-1 was visualized using HRP-conjugated secondary antibodies and the peroxidase substrate chromogen AEC (red), which produces a red reaction product. B, top row: VCAM-1 staining was not detectable in the sham surgery group. A representative VCAM-1–positive small artery situated within the injured, inflamed parenchyma is shown for the CLP+PBS group; adhered leukocytes along the VCAM-1+ endothelium are shown at higher magnification in the inset. In the CLP+PKCδ-TAT image, VCAM-1 staining is absent in the endothelium of a similarly situated small artery in the distal parenchyma. B, bottom: Cropped views of venous and arterial localization of VCAM-1. Left to right: VCAM-1 staining in the venous endothelium (CLP+PBS); absence of VCAM-1 staining in the venous endothelium (CLP+PKCδ-TAT); a large pulmonary artery with VCAM-1+ endothelium and thickened underlying interstitium (CLP+PBS); and a large pulmonary artery with absent VCAM-1 staining in the endothelium, and with normal thickness of the underlying interstitium (CLP+PKCδ-TAT). Scale bars: 100 μm (A, top); 50 μm (A, bottom, and B, top). Original magnification, ×400 (B, bottom row). PA, pulmonary artery; PV, pulmonary vein.