Increased levels of protein kinase C in lymphocytes in asthma: possible mechanism of regulation

Abstract

Asthma is an inflammatory disease of the airways. Activation of lymphocytes leads to elaboration of inflammatory mediators which are likely to initiate and perpetuate the asthmatic response. During activation of lymphocytes, the role of protein kinase C (PKC) has been emphasized. Therefore, changes in PKC activity in peripheral blood lymphocytes in bronchial asthma can be expected, which may be due to alterations in the regulatory mechanisms of the enzyme molecule. To understand the mechanism of regulation of PKC activity the effects of drugs, such as carbachol, histamine, sphingosine and disodium cromoglycate (DSCG), on the lymphocytes of healthy subjects were studied.The study included 27 asthmatic patients and 14 healthy volunteers. Disease was classified as mild, moderate-to-severe, and cases in remission. PKC activity was determined in peripheral blood lymphocytes by [ 3 H] phorbol 12,13-dibutyrate ([ 3 H]PDBu)-binding assay.A highly significant (p<0.001) increase was observed in total, cytosolic and membrane PKC activity in all of the asthmatic patients as compared to the healthy group. There was an increased translocation of PKC from cytosol to membrane in all of the groups, and the extent of translocation of the enzyme indicates physiological activation of the cells. A highly significant (p<0.001) reciprocal relationship (r=-0.47) existed between forced expiratory volume in one second (FEV1) as percentage predicted and total PKC activity in bronchial asthma. Carbachol and histamine significantly (p<0.001) increased PKC activity in lymphocytes, the increase being dose-dependent for histamine. Sphingosine or disodium cromoglycate (DSCG) brought about complete inhibition of PKC activity at 100 nM.We conclude that protein kinase C activity is increased in lymphocytes in bronchial asthma. Our findings suggest that the mediators (carbachol and histamine), and drugs (sphingosine and disodium cromoglycate) possibly exert their action on protein kinase C by influencing the regulatory domain of the enzyme.

Critical Role of Protein Kinase C (PKC) in the Onset of Airway Hypersensitivity in Ova-Sensitized Guinea Pig Model of Asthma

“…Previously, several investigators have suggested that PKC plays an active role in the progression and exacerbation of asthma [16,17]. We have also demonstrated acerbation of asthma [16,17]. We have also demonstrated that PKC antagonist sphingosine reduced the T lymphocytes activity isolated from asthmatic patients [16].…”

“…We, therefore, investigated the biochemical changes in airway hyper reactive guinea pig model of asthma and have presented evidence that PKC isoenzymes could be key mediators in the initiation of airway hypersensitivity during the onset of asthma. Previously, several investigators have suggested that PKC plays an active role in the progression and exacerbation of asthma [16,17]. We have also demonstrated acerbation of asthma [16,17].…”

“…The activation of protein kinase C (PKC) signaling pathway is one of the key players in asthma pathogenesis [14,15]. Previously, we and others have shown that inhibition of PKC reduces the activation of lymphocytes, inhibits the expression of Th2 cytokines by T lymphocytes from asthmatic patients [16,17], abolishes airway smooth muscles constriction [18], and inhibits the proliferation and structural changes in airway smooth muscle cells from asthmatic rats [19]. In another study, inhibition of PKC by calphostin-C, prevented proliferation of bovine tracheal smooth muscle cells following activation of mannose receptors by β-hexosaminidase and also abolished Ca 2+ -dependent and -independent PKC activity [20] which suggests involvement of different isoenzymes of PKC.…”

Histamine affects STAT6 phosphorylation via its effects on IL-4 secretion: Role of H1 receptors in the regulation of IL-4 production

“…It has been previously demonstrated that histamine H1 receptors can signal to the nucleus through the PKC [46] and consequently the effects of H1 receptors are PKC dependent. Elevated PKC levels were observed in lymphocytes of asthmatic patients and histamine reportedly exerted its action on the PKC activity by modulating the regulatory domain of the enzyme [47].…”

Changes in Adenosine Metabolism in Asthma. A Study on Adenosine, 5&amp;#39-NT, Adenosine Deaminase and Its Isoenzyme Levels in Serum, Lymphocytes and Erythrocytes

“…The pellet containing lymphocytes was washed twice with physiological saline. Contaminating erythrocytes were removed by giving osmotic shock to the pellet by the method of Bansal et al [37]. The cell suspension was centrifuged again, the pellet washed twice with physiological saline and resuspended in physiological saline.…”