Tissue Development, Repair, and Remodeling - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 721

Table 11.11. Leukotriene receptors (Source: [ 815 ]). These receptors have a tissue-specific ex-
pression pattern. They are classified into receptors for LTb4 (BLT 1 and BLT 2 ) and for cysteinyl
leukotrienes (LTc4, LTd4, and LTe4; CysLT 1 ,CysLT 2 , and LTe4-specific CysLT E ). Receptor
BLT 1 lodges mainly in leukocytes. BLT 2 Receptor is a low-affinity receptor or LTb4 and 12-
hydroxy-heptadecadienoic acid on leukocytes and other cell types. The CysLT receptors reside
on airway smooth myocytes, B lymphocytes, eosinophils, and monocytes (CysLT1), mastocytes
and macrophages ( CysLT1 and CysLT2), and endothelial cells (mainly CysLT 2).

Type Effect

BLT 1 Cell adhesion and chemotaxis (high affinity);

vasoconstriction

BLT 2 Leukocyte chemotaxis (low affinity)

CysLT 1 Monocyte migration;

bronchoconstriction

CysLT 2 Vascular permeability

CysLT E Eosinophil recruitment, vascular permeability

Table 11.12. Leukotriene function (Source: [ 815 ]). Leukotriene-B4 can bind to the nuclear
receptor PPAR α . Leukotrienes typically act as autacoids near their origin, via capillaries or

interstitial space.

Type Effect

5oxoETE Chemoattractant (granulocytes)

5HETE Weak activator of neutrophils and eosinophils;

pulmonary vasoconstriction

LTb4 Neutrophil chemotaxis and adhesion

CysLTs Postcapillary venule permeability;

vasoconstriction;
activation and chemotaxis of eosinophils and monocytes;
bronchoconstriction; mucus secretion

Lipoxins Reduction of neutrophil chemotaxis and extravasation;

monocyte attraction; stimulation of macrophage phagocytosis;
attenuation of edema

Leukotriene synthesis involves 5-lipoxygenase (5LOx), 5LOx-activating protein,
LTa4 hydrolase, and LTc4 synthase [ 815 ]. Messenger LTb4 targets BLT 1 and BLT 2
receptors. Leukotrienes LTc4, LTd4, and LTe4 that are designated as cysteinyl
leukotrienes (cysLT) bind to CysLT 1 ,CysLT 2 , and LTe4-specific CysLT E receptors
(Table 11.11 ). Leukotrienes possess more or less potent biological functions
(Table 11.12 ).
Prostaglandins are synthesized by cyclooxygenases. Neutrophil recruitment to
inflammatory sites by interleukins IL17 and IL23 is enhanced by prostaglandin
PGe2, but inhibited by IL12 and Ifn [ 1466 ]. Interleukin-17 is a chemoattractant for

neutrophils owing to CXC chemokines. Prostaglandin PGe2 raises IL17 production
induced by IL23 as it simultaneously impedes IL12 and Ifn

γ

γ synthesis.