RESUMO
PANoptosis is a new type of cell death featured with pyroptosis, apoptosis and necroptosis, and is implicated in organ injury and mortality in various inflammatory diseases, such as sepsis and hemophagocytic lymphohistiocytosis (HLH). Reverse electron transport (RET)-mediated mitochondrial reactive oxygen species (mtROS) has been shown to contribute to pyroptosis and necroptosis. In this study we investigated the roles of mtROS and RET in PANoptosis induced by TGF-ß-activated kinase 1 (TAK1) inhibitor 5Z-7-oxozeaenol (Oxo) plus lipopolysaccharide (LPS) as well as the effects of anti-RET reagents on PANoptosis. We showed that pretreatment with anti-RET reagents 1-methoxy PMS (MPMS) or dimethyl fumarate (DMF) dose-dependently inhibited PANoptosis in macrophages BMDMs and J774A.1 cells induced by Oxo/LPS treatment assayed by propidium iodide (PI) staining. The three arms of the PANoptosis signaling pathway, namely pyroptosis, apoptosis and necroptosis signaling, as well as the formation of PANoptosomes were all inhibited by MPMS or DMF. We demonstrated that Oxo/LPS treatment induced RET and mtROS in BMDMs, which were reversed by MPMS or DMF pretreatment. Interestingly, the PANoptosome was co-located with mitochondria, in which the mitochondrial DNA was oxidized. MPMS and DMF fully blocked the mtROS production and the formation of PANoptosome induced by Oxo plus LPS treatment. An HLH mouse model was established by poly(I:C)/LPS challenge. Pretreatment with DMF (50 mg·kg-1·d-1, i.g. for 3 days) or MPMS (10 mg·kg-1·d-1, i.p. for 2 days) (DMF i.g. MPMS i.p.) effectively alleviated HLH lesions accompanied by decreased hallmarks of PANoptosis in the liver and kidney. Collectively, RET and mtDNA play crucial roles in PANoptosis induction and anti-RET reagents represent a novel class of PANoptosis inhibitors by blocking oxidation of mtDNA, highlighting their potential application in treating PANoptosis-related inflammatory diseases. PANoptotic stimulation induces reverse electron transport (RET) and reactive oxygen species (ROS) in mitochondia, while 1-methoxy PMS and dimethyl fumarate can inhibit PANoptosis by suppressing RETmediated oxidation of mitochondrial DNA.
Assuntos
DNA Mitocondrial , Fumarato de Dimetilo , Animais , Camundongos , Espécies Reativas de Oxigênio/metabolismo , Transporte de Elétrons , Fumarato de Dimetilo/metabolismo , Fumarato de Dimetilo/farmacologia , DNA Mitocondrial/metabolismo , Lipopolissacarídeos/farmacologia , Elétrons , Mitocôndrias , ApoptoseRESUMO
Macrophages represent the first lines of innate defense against pathogenic infections and are poised to undergo multiple forms of regulated cell death (RCD) upon infections or toxic stimuli, leading to multiple organ injury. Triptolide, an active compound isolated from Tripterygium wilfordii Hook F., possesses various pharmacological activities including anti-tumor and anti-inflammatory effects, but its applications have been hampered by toxic adverse effects. It remains unknown whether and how triptolide induces different forms of RCD in macrophages. In this study, we showed that triptolide exhibited significant cytotoxicity on cultured macrophages in vitro, which was associated with multiple forms of lytic cell death that could not be fully suppressed by any one specific inhibitor for a single form of RCD. Consistently, triptolide induced the simultaneous activation of pyroptotic, apoptotic and necroptotic hallmarks, which was accompanied by the co-localization of ASC specks respectively with RIPK3 or caspase-8 as well as their interaction with each other, indicating the formation of PANoptosome and thus the induction of PANoptosis. Triptolide-induced PANoptosis was associated with mitochondrial dysfunction and ROS production. PANoptosis was also induced by triptolide in mouse peritoneal macrophages in vivo. Furthermore, triptolide caused kidney and liver injury, which was associated with systemic inflammatory responses and the activation of hallmarks for PANoptosis in vivo. Collectively, our data reveal that triptolide induces PANoptosis in macrophages in vitro and exhibits nephrotoxicity and hepatotoxicity associated with induction of PANoptosis in vivo, suggesting a new avenue to alleviate triptolide's toxicity by harnessing PANoptosis.
Assuntos
Diterpenos , Fenantrenos , Camundongos , Animais , Apoptose , Macrófagos/metabolismo , Diterpenos/efeitos adversos , Diterpenos/metabolismo , Fenantrenos/toxicidade , Fenantrenos/metabolismo , Compostos de Epóxi/toxicidade , Compostos de Epóxi/metabolismoRESUMO
Necroptosis has been implicated in various inflammatory diseases including tumor-necrosis factor-α (TNF-α)-induced systemic inflammatory response syndrome (SIRS). Dimethyl fumarate (DMF), a first-line drug for treating relapsing-remitting multiple sclerosis (RRMS), has been shown to be effective against various inflammatory diseases. However, it is still unclear whether DMF can inhibit necroptosis and confer protection against SIRS. In this study, we found that DMF significantly inhibited necroptotic cell death in macrophages induced by different necroptotic stimulations. Both the autophosphorylation of receptor-interacting serine/threonine kinase 1 (RIPK1) and RIPK3 and the downstream phosphorylation and oligomerization of MLKL were robustly suppressed by DMF. Accompanying the suppression of necroptotic signaling, DMF blocked the mitochondrial reverse electron transport (RET) induced by necroptotic stimulation, which was associated with its electrophilic property. Several well-known anti-RET reagents also markedly inhibited the activation of the RIPK1-RIPK3-MLKL axis accompanied by decreased necrotic cell death, indicating a critical role of RET in necroptotic signaling. DMF and other anti-RET reagents suppressed the ubiquitination of RIPK1 and RIPK3, and they attenuated the formation of necrosome. Moreover, oral administration of DMF significantly alleviated the severity of TNF-α-induced SIRS in mice. Consistent with this, DMF mitigated TNF-α-induced cecal, uterine, and lung damage accompanied by diminished RIPK3-MLKL signaling. Collectively, DMF represents a new necroptosis inhibitor that suppresses the RIPK1-RIPK3-MLKL axis through blocking mitochondrial RET. Our study highlights DMF's potential therapeutic applications for treating SIRS-associated diseases.
Assuntos
Proteínas Quinases , Fator de Necrose Tumoral alfa , Camundongos , Animais , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Quinases/metabolismo , Fumarato de Dimetilo , Necroptose , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Síndrome de Resposta Inflamatória Sistêmica , Fosforilação Oxidativa , ApoptoseRESUMO
Activation of NLR family pyrin domain-containing 3 (NLRP3) inflammasome plays important role in defending against infections, but its aberrant activation is causally linked to many inflammatory diseases, thus being a therapeutic target for these diseases. Theaflavin, one major ingredient of black tea, exhibits potent anti-inflammatory and anti-oxidative activities. In this study, we investigated the therapeutic effects of theaflavin against NLRP3 inflammasome activation in macrophages in vitro and in animal models of related diseases. We showed that theaflavin (50, 100, 200 µM) dose-dependently inhibited NLRP3 inflammasome activation in LPS-primed macrophages stimulated with ATP, nigericin or monosodium urate crystals (MSU), evidenced by reduced release of caspase-1p10 and mature interleukin-1ß (IL-1ß). Theaflavin treatment also inhibited pyroptosis as shown by decreased generation of N-terminal fragment of gasdermin D (GSDMD-NT) and propidium iodide incorporation. Consistent with these, theaflavin treatment suppressed ASC speck formation and oligomerization in macrophages stimulated with ATP or nigericin, suggesting reduced inflammasome assembly. We revealed that theaflavin-induced inhibition on NLRP3 inflammasome assembly and pyroptosis resulted from ameliorated mitochondrial dysfunction and reduced mitochondrial ROS production, thereby suppressing interaction between NLRP3 and NEK7 downstream of ROS. Moreover, we showed that oral administration of theaflavin significantly attenuated MSU-induced mouse peritonitis and improved the survival of mice with bacterial sepsis. Consistently, theaflavin administration significantly reduced serum levels of inflammatory cytokines including IL-1ß and attenuated liver inflammation and renal injury of mice with sepsis, concomitant with reduced generation of caspase-1p10 and GSDMD-NT in the liver and kidney. Together, we demonstrate that theaflavin suppresses NLRP3 inflammasome activation and pyroptosis by protecting mitochondrial function, thus mitigating acute gouty peritonitis and bacterial sepsis in mice, highlighting a potential application in treating NLRP3 inflammasome-related diseases.
Assuntos
Gota , Peritonite , Sepse , Camundongos , Animais , Inflamassomos/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Espécies Reativas de Oxigênio , Nigericina/uso terapêutico , Peritonite/tratamento farmacológico , Antioxidantes/uso terapêutico , Sepse/complicações , Sepse/tratamento farmacológico , Caspases , Trifosfato de Adenosina , Interleucina-1beta/metabolismoRESUMO
PANoptosis is manifested with simultaneous activation of biomarkers for both pyroptotic, apoptotic and necroptotic signaling via the molecular platform PANoptosome and it is involved in pathologies of various inflammatory diseases including hemophagocytic lymphohistiocytosis (HLH). Scutellarin is a flavonoid isolated from herbal Erigeron breviscapus (Vant.) Hand.-Mazz. and has been shown to possess multiple pharmacological effects, but it is unknown whether scutellarin has any effects on PANoptosis and related inflammatory diseases. In this study, we found that scutellarin inhibited cell death in bone marrow-derived macrophages (BMDMs) and J774A.1 cells treated with TGF-ß-activated kinase 1 (TAK1) inhibitor 5Z-7-oxozeaenol (OXO) plus lipopolysaccharide (LPS), which has been commonly used to induce PANoptosis. Western blotting showed that scutellarin dose-dependently inhibited the activation biomarkers for pyroptotic (Caspase-1p10 and GSDMD-NT), apoptotic (cleaved Casp3/8/9 and GSDME-NT), and necroptotic (phosphorylated MLKL) signaling. The inhibitory effect of scutellarin was unaffected by NLRP3 or Caspase-1 deletion. Interestingly, scutellarin blocked the assembly of PANoptosome that encompasses ASC, RIPK3, Caspase-8 and ZBP1, suggesting its action on upstream signaling. Consistent with this, scutellarin inhibited mitochondrial damage and mitochondrial reactive oxygen species (mtROS) generation in cells treated with OXO+LPS. Further, mito-TEMPO that can scavenge mtROS significantly inhibited OXO+LPS-induced PANoptotic cell death. In line with the in vitro results, scutellarin markedly alleviated systemic inflammation, multiple organ injury, and activation of PANoptotic biomarkers in mice with HLH. Collectively, our data suggest that scutellarin can inhibit PANoptosis by suppressing mitochondrial damage and mtROS generation and thereby mitigating multiple organ injury in mice with inflammatory disorders.
Assuntos
Apigenina , Glucuronatos , Lipopolissacarídeos , Camundongos Endogâmicos C57BL , Mitocôndrias , Espécies Reativas de Oxigênio , Apigenina/farmacologia , Apigenina/uso terapêutico , Glucuronatos/farmacologia , Glucuronatos/uso terapêutico , Animais , Espécies Reativas de Oxigênio/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Camundongos , Linhagem Celular , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/imunologia , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Necroptose/efeitos dos fármacos , Masculino , MAP Quinase Quinase Quinases/metabolismo , Inflamação/tratamento farmacológico , Transdução de Sinais/efeitos dos fármacos , Zearalenona/administração & dosagem , Lactonas , ResorcinóisRESUMO
Necroptosis is a necrotic form of regulated cell death, which is primarily mediated by the receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like (MLKL) pathway in a caspase-independent manner. Necroptosis has been found to occur in virtually all tissues and diseases evaluated, including pancreatitis. Celastrol, a pentacyclic triterpene extracted from the roots of Tripterygium wilfordii (thunder god vine), possesses potent anti-inflammatory and anti-oxidative activities. Yet, it is unclear whether celastrol has any effects on necroptosis and necroptotic-related diseases. Here we showed that celastrol significantly suppressed necroptosis induced by lipopolysaccharide (LPS) plus pan-caspase inhibitor (IDN-6556) or by tumor-necrosis factor-α in combination with LCL-161 (Smac mimetic) and IDN-6556 (TSI). In these in vitro cellular models, celastrol inhibited the phosphorylation of RIPK1, RIPK3, and MLKL and the formation of necrosome during necroptotic induction, suggesting its possible action on upstream signaling of the necroptotic pathway. Consistent with the known role of mitochondrial dysfunction in necroptosis, we found that celastrol significantly rescued TSI-induced loss of mitochondrial membrane potential. TSI-induced intracellular and mitochondrial reactive oxygen species (mtROS), which are involved in the autophosphorylation of RIPK1 and recruitment of RIPK3, were significantly attenuated by celastrol. Moreover, in a mouse model of acute pancreatitis that is associated with necroptosis, celastrol administration significantly reduced the severity of caerulein-induced acute pancreatitis accompanied by decreased phosphorylation of MLKL in pancreatic tissues. Collectively, celastrol can attenuate the activation of RIPK1/RIPK3/MLKL signaling likely by attenuating mtROS production, thereby inhibiting necroptosis and conferring protection against caerulein-induced pancreatitis in mice.
Assuntos
Pancreatite , Camundongos , Animais , Pancreatite/induzido quimicamente , Pancreatite/tratamento farmacológico , Proteínas Quinases/metabolismo , Necroptose , Ceruletídeo , Doença Aguda , Triterpenos Pentacíclicos , Caspases/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , ApoptoseRESUMO
Discovery of anti-inflammatory drugs that can suppress T lymphocyte activation and proliferation by inhibiting TCR/CD3 and IL-2/IL-2R signaling is still needed in clinic, though rapamycin and other related reagents have made great success. Taraxasterol (TAS) is an active ingredient of dandelion, an anti-inflammatory medicinal herb with low in vivo toxicity that has long been used in China. Yet the action mechanism of TAS on lymphocytes remains elusive. The anti-inflammatory effects of TAS were evaluated in C57BL/6 mouse primary lymphocytes stimulated with concanavalin A (Con A) in vitro and in mouse model of Con A-induced acute hepatitis in vivo. Our results showed that TAS significantly suppressed Con A-induced acute hepatitis in a mouse model, reducing the hepatic necrosis areas, the release of aminotransferases, and the production of IL-2 and other inflammatory cytokines. Supporting this, in vitro study also showed that TAS reduced the production of IL-2 and the expression of IL-2 receptor subunit α (CD25) upon the stimulation of Con A, which was likely mediated by suppressing NF-κB activation. The downstream pathways of IL-2/IL-2R signaling, including the activation of PI3K/PDK1/mTOR, STAT3 and STAT5, were also suppressed by TAS. Consistently, Con A-induced T cell proliferation was also inhibited by TAS in vitro. Our data indicate that TAS can suppress both T lymphocyte activation and cell proliferation by down-regulating IL-2 expression and its signaling pathway thereby ameliorating Con A-induced acute hepatitis, highlighting TAS as a potential drug candidate for treating inflammatory diseases including autoimmune hepatitis.
Assuntos
Anti-Inflamatórios/uso terapêutico , Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Interleucina-2/imunologia , Esteróis/uso terapêutico , Linfócitos T/efeitos dos fármacos , Triterpenos/uso terapêutico , Animais , Anti-Inflamatórios/farmacologia , Proliferação de Células/efeitos dos fármacos , Doença Hepática Induzida por Substâncias e Drogas/sangue , Doença Hepática Induzida por Substâncias e Drogas/imunologia , Doença Hepática Induzida por Substâncias e Drogas/patologia , Concanavalina A , Citocinas/sangue , Feminino , Fígado/efeitos dos fármacos , Fígado/imunologia , Fígado/patologia , Camundongos Endogâmicos C57BL , Transdução de Sinais/efeitos dos fármacos , Esteróis/farmacologia , Linfócitos T/imunologia , Triterpenos/farmacologiaRESUMO
Colonic patches, the counterparts of Peyer's patches in the small intestine, are dynamically regulated lymphoid tissues in the colon that have an important role in defensing against microbial infections. Berberine is an isoquinoline alkaloid extracted from medicinal herbs including Rhizoma coptidis and has long been used for the treatment of infectious gastroenteritis, but its impact on the colonic lymphoid tissues (such as colonic patches) is unknown. In this study, we aimed to investigate whether berberine had any influences on the colonic patches in mice with bacterial infection. The results showed that oral berberine administration in bacterial infected mice substantially enhanced the hypertrophy of colonic patches, which usually possessed the features of two large B-cell follicles with a separate T-cell area. Moreover, the colonic patches displayed follicular dendritic cell networks within the B-cell follicles, indicative of mature colonic patches containing germinal centers. Concomitant with enlarged colonic patches, the cultured colon of infected mice treated with berberine secreted significantly higher levels of interleukin-1ß (IL-1ß), IL-6, TNF-α, and CCL-2, while NLRP3 inhibitor MMC950 or knockout of NLRP3 gene abrogated berberine-induced hypertrophy of colonic patches, suggesting the involvement of the NLRP3 signaling pathway in this process. Functionally, oral administration of berberine ameliorated liver inflammation and improved formed feces in the colon. Altogether, these results indicated that berberine was able to augment the hypertrophy of colonic patches in mice with bacterial infection probably through enhancing local inflammatory responses in the colon.
Assuntos
Infecções Bacterianas/patologia , Berberina/uso terapêutico , Colo/efeitos dos fármacos , Tecido Linfoide/efeitos dos fármacos , Doenças Peritoneais/patologia , Animais , Linfócitos B/efeitos dos fármacos , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/metabolismo , Colo/crescimento & desenvolvimento , Colo/patologia , Citocinas/metabolismo , Células Dendríticas/efeitos dos fármacos , Feminino , Gastroenterite/tratamento farmacológico , Tecido Linfoide/crescimento & desenvolvimento , Tecido Linfoide/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR/antagonistas & inibidores , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Doenças Peritoneais/tratamento farmacológico , Doenças Peritoneais/metabolismo , Linfócitos T/efeitos dos fármacosRESUMO
The flavonoid baicalin has been reported to possess potent anti-inflammatory activities by suppressing inflammatory signaling pathways. However, whether baicalin can suppress the activation of NOD-like receptor (NLR) family, pyrin containing domain 3 (NLRP3) inflammasome in macrophages is largely unknown. Here, we showed that baicalin treatment dose-dependently inhibited adenosine triphosphate (ATP) or nigericin-induced NLRP3 inflammasome activation, as revealed by the decreased release of mature interleukin (IL)-1ß, active caspase-1p10, and high-mobility group box-1 protein from lipopolysaccharide (LPS)-primed bone marrow-derived macrophages. The formation of ASC specks, a critical marker of NLRP3 inflammasome assembly, was robustly inhibited by baicalin in the macrophages upon ATP or nigericin stimulation. All these inhibitory effects of baicalin could be partly reversed by MDL12330A or H89, both of which are inhibitors of the protein kinase A (PKA) signaling pathway. Consistent with this, baicalin strongly enhanced PKA-mediated phosphorylation of NLRP3, which has been suggested to prevent ASC recruitment into the inflammasome. Of note, the PKA inhibitor H89 could block baicalin-induced NLRP3 phosphorylation on PKA-specific sites, further supporting PKA's role in this process. In addition, we showed that when administered pre and post exposure to Escherichia coli infection baicalin treatment significantly improved mouse survival in bacterial sepsis. Baicalin administration also significantly reduced IL-1ß levels in the sera of bacterial infected mice. Altogether, our results revealed that baicalin inhibited NLRP3 inflammasome activation at least partly through augmenting PKA signaling, highlighting its therapeutic potential for the treatment of NLRP3-related inflammatory diseases.
RESUMO
Pepper, a daily-used seasoning for promoting appetite, is widely used in folk medicine for treating gastrointestinal diseases. Piperine is the major alkaloid in pepper and possesses a wide range of pharmacological activities. However, the mechanism for linking metabolic and medicinal activities of piperine remains unknown. Here we report that piperine robustly boosts mTORC1 activity by recruiting more system L1 amino acid transporter (SLC7A5/SLC3A2) to the cell membrane, thus promoting amino acid metabolism. Piperine-induced increase of mTORC1 activity in resident peritoneal macrophages (pMΦs) is correlated with enhanced production of IL-6 and TNF-α upon LPS stimulation. Such an enhancement of cytokine production could be abrogated by inhibitors of the mTOR signaling pathway, indicating mTOR's action in this process. Moreover, piperine treatment protected resident pMΦs from bacterium-induced apoptosis and disappearance, and increased their bacterial phagocytic ability. Consequently, piperine administration conferred mice resistance against bacterial infection and even sepsis. Our data highlight that piperine has the capacity to metabolically reprogram peritoneal resident macrophages to fortify their innate functions against bacterial infection.
Assuntos
Alcaloides/farmacologia , Aminoácidos/metabolismo , Antibacterianos/farmacologia , Benzodioxóis/farmacologia , Infecções por Escherichia coli/prevenção & controle , Escherichia coli/efeitos dos fármacos , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/efeitos dos fármacos , Piperidinas/farmacologia , Alcamidas Poli-Insaturadas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Modelos Animais de Doenças , Escherichia coli/imunologia , Escherichia coli/patogenicidade , Infecções por Escherichia coli/imunologia , Infecções por Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/patologia , Feminino , Cadeia Pesada da Proteína-1 Reguladora de Fusão/metabolismo , Células HeLa , Humanos , Imunidade Inata/efeitos dos fármacos , Mediadores da Inflamação/metabolismo , Interleucina-6/metabolismo , Transportador 1 de Aminoácidos Neutros Grandes/genética , Transportador 1 de Aminoácidos Neutros Grandes/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/metabolismo , Macrófagos Peritoneais/microbiologia , Macrófagos Peritoneais/patologia , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Camundongos , Camundongos Endogâmicos C57BL , Complexos Multiproteicos/metabolismo , Fagocitose/efeitos dos fármacos , Células RAW 264.7 , Interferência de RNA , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Fatores de Tempo , Transfecção , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, has been proven to be an anti-cancer agent. Its anti-inflammatory activities have recently been observed both in in vitro and in vivo models. Yet its action on lymphocytes and the underlying mechanism are still not well known. In this study, in order to evaluate the anti-inflammatory function of SAHA, we analyzed the effects of SAHA on the proliferation, activation, cytokines secretion, cell cycle distribution and apoptosis of murine lymphocytes activated with concanavalin A (Con A). Our results demonstrated that SAHA inhibited the proliferation of Con A-activated lymphocytes in a dose-dependent manner. The expression of CD69 on CD3(+) T lymphocytes was significantly inhibited by SAHA. Intracellular cytokine staining analysis showed that SAHA could downregulate the expression of pro-inflammatory cytokines TNF-α, IL-6 and IFN-γ in T lymphocytes. Furthermore, analysis of sub-G(0)/G(1) peaks and annexin V binding populations revealed that SAHA induced apoptotic cell death in Con A-activated lymphocytes. Consistent with these results, SAHA treatment also induced a decrease of mitochondrial membrane potential and cleavage of caspase-3 and PARP in these cells. Moreover, SAHA caused an accumulation of phosphorylated histone H2A.X, indicating increased double strand DNA breaks. These findings suggest that induction of apoptosis through the mitochondrial pathway may contribute to the anti-inflammatory activities of SAHA on activated lymphocytes.