Induction of thromboxane A2 synthesizing enzymes in DMSO-induced granulocytic differentiation of HL-60 cells

Optimization of cell-based assays to quantify the anti-inflammatory/allergic potential of test substances in 96-well format

OBJECTIVE

There is an insistent need for robust, reliable, and optimized assays for screening novel drugs targeting the inflammatory/allergic markers. The present study describes about the optimization of eight cell-based assays utilizing mammalian cell lines in 96-well format for quantifying anti-inflammatory/allergic drug candidates.

MATERIALS AND METHODS

We estimated the inhibitory response of reference compounds: 1400 W dihydrochloride on LPS-induced NO release, celecoxib on LPS-induced PGE(2) production and dexamethasone on LPS-induced pro-inflammatory cytokines IL-1 beta, IL-6, and TNF-alpha production by J774A.1 murine macrophages. Response of acetylsalicylic acid and celecoxib was studied on A23187-induced TXB(2) production; captopril on A23187-stimulated LTB(4) production by HL-60 cells. Effect of ketotifen fumarate was evaluated on A23187-elicited histamine release by RBL-2H3 cells. Each experiment was repeated twice to assess the reproducibility and suitability of the assays by determining appropriate statistical tools viz. %CV, S/B and Z' factor.

RESULTS

1400 W dihydrochloride was capable of inhibiting LPS-induced NO levels (IC(50) = 10.7 μM). Dexamethasone attenuated LPS-induced IL-1 beta (IC(50) = 70 nM), IL-6 (IC(50) = 58 nM) and TNF-alpha (IC(50) = 44 nM) release, whereas celecoxib, a specific COX-2 inhibitor showed marked reduction in LPS-induced PGE(2) (IC(50) = 23 nM) production. Captopril (IC(50) = 48 μM) and ketotifen fumarate (IC(50) = 36.4 μM) demonstrated potent inhibitory effect against A23187-stimulated LTB(4) and histamine levels, respectively. Both acetylsalicylic acid (IC(50) = 5.5 μM) and celecoxib (IC(50) = 7.9 nM) exhibited concentration-dependent decrease in TXB(2) production. Results for all the cell assays from two experiments showed a Z' factor varying from 0.30 to 0.99; the S/B ratio ranged from 2.39 to 24.92; %CV ranged between 1.52 and 20.14.

CONCLUSION

The results proclaim that these cell-based assays can act as ideal tools for screening new anti-inflammatory/anti-allergic compounds.

Lipid mediators and human leukemic blasts

Some of the most potent inflammatory mediators share a lipid origin. They regulate a wide spectrum of cellular processes including cell proliferation and apoptosis. However, the precise roles and ways (if any) in which these compounds impact the growth and apoptosis of leukemic blasts remain incompletely resolved. In spite of this, significant advances have been recently made. Here we briefly review the current knowledge about the production of lipid mediators (prostaglandins, leukotrienes, platelet-activating factor) by leukemic blasts, the enzymatic activities (phospholipase A₂, cyclooxygenases, lipoxygenases) involved in their productions and their effects (through specific membrane bound receptors) on the growth, and apoptosis of leukemic blasts.

Effect of an extract of Andrographis paniculata leaves on inflammatory and allergic mediators in vitro

AIM OF STUDY

Andrographis paniculata has been known to possess widespread traditional application in the treatment of allergy and inflammatory diseases. In the current study, we sought to examine the effects of an extract of Andrographis paniculata leaves on inhibition of lipopolysaccharide (LPS) induced [nitric oxide (NO), prostaglandin E(2) (PGE(2)), interleukin-1beta (IL-1 beta), and interleukin-6 (IL-6)] and calcimycin (A23187) induced [leukotriene B(4) (LTB(4)), thromboxane B(2) (TXB(2)) and histamine] mediators in diverse cell based models.

MATERIALS AND METHODS

Effect of an extract of Andrographis paniculata leaves (AP) was studied on inhibition of LPS induced NO, PGE(2), IL-1 beta and IL-6 in J774A.1 murine macrophages; A23187 induced LTB(4) and TXB(2) in HL-60 promyelocytic leukemic cells and histamine in RBL-2H3 rat basophilic leukemia cells.

RESULTS AND CONCLUSION

AP illustrated significant alleviation of pro-inflammatory, inflammatory, and allergic mediators. However, no inhibition was observed against histamine release. This outcome has been summed up to deduce that AP is fairly potent in attenuating the inflammation by inhibiting pro-inflammatory (NO, IL-1 beta and IL-6), inflammatory (PGE(2) and TXB(2)) and allergic (LTB(4)) mediators.