INHIBITION OF CLASS I SIRTUIN ACTIVITY PROMOTES NEUTROPHIL ACTIVATION AND SURVIVAL

BLEICHMAR, LUCÍA; MAZZITELLI, IGNACIO; MELUCCI GANZARAIN, CLAUDIA; GEFFNER, JORGE; DIAZ, FERNANDO ERRA

Congreso; REUNIÓN CONJUNTA SAIC SAI & FAIC SAFIS 2022; 2022

Sirtuins are a family of NAD dependent enzymes that control the acetylation state of a wide variety of histone and non-histone pro- teins. Due to their deacetylase activity, Sirtuins modulate many cel- lular functions and are known to participate in the regulation of cell metabolism and aging. Sirtuin family comprises SIRT1 to SIRT7 and it can be divided into four classes: class I (SIRT1-SIRT3), class II (SIRT4), class III (SIRT5) and class IV (SIRT6, SIRT7). Here we studied the effect of the class I Sirtuin inhibitor EX-527 on human neutrophils. Neutrophils were purified from peripheral blood by con- ventional procedures (% purity >97%). By qPCR we found that hu- man neutrophils express SIRT2, SIRT3, SIRT5 and SIRT6 genes. We also found that the class I SIRT inhibitor, compound EX-527 (100 μM), significantly increased (p=0.0313, n=6) the production of ROS evaluated by dihydrorhodamine oxidation and flow cytometry, induced by fMLP (100 nM), at 20 min of incubation: % increase = 220 ± 62. It also modestly increased the survival of resting neu- trophils (Annexin V/propidium staining and flow cytometry) evalu- ated at 18hs of culture: % viable neutrophils 24 ± 3.4 and 30 ± 3.8 (n=12, p=0.043), for cells cultured in the absence or presence of EX-527, respectively. Interestingly, this anti-apoptotic effect was further increased when neutrophils were cultured at pH values similar to those found in inflammatory tissues (pH 6.0): % viable neutrophils 40 ± 4.1 and 71 ± 3.3, for neutrophils cultured without or with EX- 527 (n=12, p=0.0005). Moreover, we found that EX-527 significantly (p