ATR blockade reduces IFN-gamma production in lymphocytes in vivo and in vitro.
BACKGROUND
Type 1 angiotensin II (Ang II) receptor (AT(1)R) signaling induces proinflammatory responses. Recent studies suggest that T lymphocytes express AT(1)R; yet the effects of Ang II binding to AT(1)R on T cells are poorly understood. We examined the effect of AT(1)R blockade on release of the proinflammatory cytokine, interferon-gamma (IFN-gamma) by human lymphocytes in vivo and in vitro.


METHODS
We used an AT(1)R blocker losartan in a randomized clinical trial in kidney transplant recipients over a 12-month period [AT(1)R blocker (N= 11) and control (N= 10)]. Peripheral blood lymphocytes, isolated from both cohorts, were analyzed by enzyme-linked immunosorbent spot assays (ELISPOT) analyses and real-time reverse transcription-polymerase chain reaction (RT-PCR) to enumerate IFN-gamma producing T cells and IFN-gamma mRNA levels. The effects of AT(1)R blockade in vitro were assessed using human alloreactive T cells and an IFN-gamma producing human cytotoxic T-lymphocyte line. Alloreactive T cells were treated with losartan or candesartan and enzyme-linked immunosorbant assay (ELISA) was used to measure IFN-gamma protein release. The cytotoxic T-lymphocyte line also was AT(1)R blocker-treated prior to determining IFN-gamma producing cells by intracellular cytokine staining.


RESULTS
The AT(1)R blocker cohort had a significant decrease in IFN-gamma producing peripheral blood lymphocytes (P< or = 0.05 for each time point) and IFN-gamma mRNA levels (P= 0.01 vs. control patients). Losartan also decreased IFN-gamma production (P < 0.001) in purified alloreactive T cells in vitro as did candesartan. Moreover, Ang II amplified IFN-gamma generation (P < 0.05) in alloreactive T cells while AT(1)R blocker treatment inhibited Ang II's effect (P < 0.04). AT(1)R blocker treatment furthermore also inhibited IFN-gamma production in the cytotoxic T-lymphocyte line.


CONCLUSIONS
AT(1)R blockers may have a clinically relevant immunomodulatory role by blocking IFN-gamma production in T cells.
Weidanz
Jon A
JA
Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, Texas, USA.
Jacobson
Lynn M
LM
Muehrer
Rebecca J
RJ
Djamali
Arjang
A
Hullett
Debra A
DA
Sprague
Jenifer
J
Chiriva-Internati
Maurizio
M
Wittman
Vaughan
V
Thekkumkara
Thomas J
TJ
Becker
Bryan N
BN
D000328:Adult; D000368:Aged; D000804:Angiotensin II / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology; D001713:Biphenyl Compounds; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000235:genetics; D019808:Losartan / Q000494:pharmacology; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D013777:Tetrazoles / Q000494:pharmacology
D047228:Angiotensin II Type 1 Receptor Blockers; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D012333:RNA, Messenger; D013777:Tetrazoles; D000804:Angiotensin II; D007371:Interferon-gamma; D019808:Losartan; C081643:candesartan