Picroside II Improves Severe Acute Pancreatitis-Induced Hepatocellular Injury in Rats by Affecting JAK2/STAT3 Phosphorylation Signaling.

Picroside II is an important ingredient agent in Traditional Chinese medicine and hoped to reduce hepatocellular injury caused by severe acute pancreatitis (SAP). An SAP-induced hepatocellular injury model was established in rats by using pentobarbital sodium. 27 rats were divided into 3 groups: the sham group (SG), model group (MG), and Picroside groups (PG). SAP-induced hepatocellular injury was assessed using hematoxylin and eosin staining. We measured hepatocellular enzymes (amylase (AMY), alanine aminotransferase (ALT), and aspartate aminotransferase (AST)), oxidative stress factors (superoxidase dismutase (SOD) and malondialdehyde (MDA)), and inflammatory factors (tumor necrosis factor α (TNF-α), interleukin- (IL-) 6, and IL-10), apoptotic factors (BAX and cleaved caspase 3), and inflammatory signaling (Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3), p-JAK2, and p-STAT3) in hepatocellular tissues. The SAP-induced hepatocellular injury model was successfully established. Picroside II treatment repaired hepatocellular injury by reducing the activities of AMY, ALT, and AST; reducing the levels of MDA, TNF-α, IL-1, IL-6, p-JAK2, p-STAT3, BAX, and cleaved caspase 3; and increasing the levels of SOD and IL-10. Picroside II exerted protective function for the SAP-induced hepatocellular injury model. Picroside II improved SAP-induced hepatocellular injury and antioxidant and anti-inflammatory properties by affecting JAK2/STAT3 phosphorylation signaling.

Kuijieyuan Decoction Improved Intestinal Barrier Injury of Ulcerative Colitis by Affecting TLR4-Dependent PI3K/AKT/NF-κB Oxidative and Inflammatory Signaling and Gut Microbiota.

ETHNOPHARMACOLOGICAL RELEVANCE: In Traditional Chinese medicine (TCM) theory, ulcerative colitis (UC) is associated with damp-heat, blood stasis, and intestinal vascular ischemia. Kuijieyuan decoction (KD) is a traditional Chinese medicine based on the above theory and used clinically to alleviate UC injury. METHODS: The main components of KD were analyzed by using high-pressure liquid chromatography (HPLC) and confirmed by UPLC-MS/MS. A UC model was established in rats by using dextran sulfate sodium (DSS) and dead rats (caused by DSS) were excluded from the study. Forty-eight rats were divided into 6 groups, health control (CG), UC model (UG), sulfasalazine (SG), low-dose KD (LG), middle-dose KD (MG), and high-dose KD (HG) groups. UC damage was assessed by hematoxylin and eosin staining and scan electron microscopy. We measured Toll-like receptor 4 (TLR4), p-phosphatidylinositol 3-kinase (PI3K), PI3K, p-Protein kinase B (AKT), AKT, p-nuclear factor kappa B (NF-κB), NF-κB, oxidative stress marker (superoxidase dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), and malondialdehyde) and inflammatory markers (tumor necrosis factor α (TNFα), interleukin (IL)-1, IL-6 and IL-10) in UC tissues. Gut microbiota was analyzed through16S rRNA sequencing. RESULTS: The main components of KD consist of gallic acid, paeoniflorin, emodin, berberine, coptisine, palmatine, jatrorrhizine, baicalein and baicalin. The UC model was successfully established by causing intestinal barrier injury with the loss of intestinal villi and destructed mitochondria of intestinal epithelial cells. Both sulfasalazine and KD treatment repaired UC injury, reduced the levels of malondialdehyde, TNFα, IL-1, IL-6, TLR4, p-PI3K, p-AKT, and p-NF-κB, and increased the levels of SOD, GPx, CAT, and IL-10. KD showed a protective function for the UC model in a dose-dependent way. The serum levels of paeoniflorin and baicalin had a strong relationship with the levels of inflammatory and oxidative stress biomarkers. KD treatment increased the proportion of Alloprevotella, Treponema, Prevotellaceae, and Prevotella, and reduced the proportion of Escherichia_Shigella and Desulfovibrio in gut microbiota. CONCLUSIONS: KD improved intestinal barrier injury of ulcerative colitis, antioxidant and anti-inflammatory properties by affecting TLR4-dependent PI3K/AKT/NF-κB signaling possibly through the combination of its main compounds, and improving gut microbiota.

Picroside II Improves Severe Acute Pancreatitis-Induced Intestinal Barrier Injury by Inactivating Oxidative and Inflammatory TLR4-Dependent PI3K/AKT/NF-κB Signaling and Improving Gut Microbiota.

BACKGROUND: Picroside II exerts anti-inflammatory and antidiarrheal effects for treating the diseases associated with oxidative injury. However, its function on pancreatitis-induced intestinal barrier injury remains unclear. Hypothesis/Purpose. We hypothesized that picroside II will have protective effects against pancreatitis-induced intestinal barrier injury by affecting oxidative and inflammatory signaling (Toll-like receptor 4- (TLR4-) dependent phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and nuclear factor kappa B (NF-κB)). Study Design and Methods. A Sprague-Dawley (SD) rat model with severe acute pancreatitis (SAP) was induced via the injection of sodium taurocholate (4% wt/vol; 1 mL/kg). All rats were divided into 3 groups: sham (CG), SAP-induced intestinal barrier injury (MG), and picroside II (PG) groups. Intestinal barrier injury was assessed by scanning electron microscopy (SEM), hematoxylin and eosin staining, and pathological scores. We measured the levels of pancreatitis biomarkers (amylase and lipase), oxidative and inflammatory signaling (TLR4-dependent PI3K/AKT/NF-κB), oxidative stress marker (superoxidase dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), and malondialdehyde), and inflammatory markers (tumor necrosis factor α (TNFα), interleukin- (IL-) 1, IL-6, and IL-10) in serum and/or gut tissues. Gut microbiota composition in feces was measured by using 16S rRNA sequencing. RESULTS: SEM showed that intestinal barrier injury was caused with the loss of intestinal villi and mitochondria destruction, and pathological scores were increased in the MG group. The levels of amylase, lipase, malondialdehyde, TNFα, IL-1, IL-6, TLR4, PI3K, AKT, and NF-κB were increased, and the levels of SOD, GPx, CAT, and IL-10 was reduced in the MG group when compared with CG group (P < 0.05). Picroside II treatment inhibited the symptoms in the MG group and showed antioxidant and anti-inflammatory activities. The serum levels of picroside II had strong correlation with the levels of inflammatory and oxidative stress biomarkers (P < 0.05). Picroside II treatment increased the proportion of Lactobacillus and Prevotella and decreased the proportion of Helicobacter and Escherichia_Shigella in the model. CONCLUSIONS: Picroside II improved the SAP-induced intestinal barrier injury in the rat model by inactivating oxidant and inflammatory signaling and improving gut microbiota.

Hydrostatin-SN10 Ameliorates Pancreatitis-Induced Lung Injury by Affecting IL-6-Induced JAK2/STAT3-Associated Inflammation and Oxidative Stress.

Hydrostatin-SN1 (peptide sequence, DEQHLETELHTLTSVLTANGFQ), a kind of peptides extracted from snake venom, has been reported to have anti-inflammatory effect, but its truncated mutant hydrostatin-SN10 (peptide sequence, DEQHLETELH) on pancreatitis-induced acute lung injury has not been well documented. Interleukin- (IL-) 6-induced Janus Kinase 2/Signal Transducer and Activator of Transcription 3 (JAK2/STAT3) pathway is involved with inflammatory and oxidative stress activities and may be associated with the pathogenesis of lung injury, and related molecules were measured. Taurocholate-induced pancreatitis associated with acute lung injury was established and treated with hydrostatin-SN10. Pancreatitis was confirmed by measuring the serum levels of amylase, lipase, and trypsinogen and urinary amylase. Lung injury was determined by histologically assessing acinar cell changes. The related molecules of IL-6-induced JAK2/STAT3-associated inflammation and oxidative stress were quantitated by real time-PCR, Western blot, and/or immunochemical assay. Hydrostatin-SN10 reduced the levels of serum amylase, lipase, and trypsinogen and urinary amylase when compared with the model group (p < 0.05). Hydrostatin-SN10 significantly inhibited the IL-6-stimulated JAK2/STAT3 pathway and reduced the number of apoptotic cells via the downregulation of caspase 3 and BAX (proapoptotic) and upregulation of Bcl2 (antiapoptotic) (p < 0.05). IL-6 induced the increase in the levels of JAK2 and STAT3, which was reversed by hydrostatin-SN10 treatment (p < 0.05). In addition, hydrostatin-SN10 reduced the expression of IL-6 and TNF- (tumor necrosis factor-) α and increased the level of IL-10 (p < 0.05). On the other hand, hydrostatin-SN10 treatment increased the levels of superoxide dismutase (SOD) and reduced glutathione (GSH) and the levels of malondialdehyde (MDA) and alanine aminotransferase (ALT) (p < 0.05). These results suggest that hydrostatin-SN10 may inhibit pancreatitis-induced acute lung injury by affecting IL-6-mediated JAK2/STAT3 pathway-associated inflammation and oxidative stress.

Blockade of TNF receptor superfamily 1 (TNFR1)-dependent and TNFR1-independent cell death is crucial for normal epidermal differentiation.

BACKGROUND: A delicate balance between cell death and keratinocyte proliferation is crucial for normal skin development. Previous studies have reported that cellular FLICE (FADD-like ICE)-inhibitory protein plays a crucial role in prevention of keratinocytes from TNF-α-dependent apoptosis and blocking of dermatitis. However, a role for cellular FLICE-inhibitory protein in TNF-α-independent cell death remains unclear. OBJECTIVE: We investigated contribution of TNF-α-dependent and TNF-α-independent signals to the development of dermatitis in epidermis-specific Cflar-deficient (CflarE-KO) mice. METHODS: We examined the histology and expression of epidermal differentiation markers and inflammatory cytokines in the skin of CflarE-KO;Tnfrsf1a+/- and CflarE-KO;Tnfrsf1a-/- mice. Mice were treated with neutralizing antibodies against Fas ligand and TNF-related apoptosis-inducing ligand to block TNF-α-independent cell death of CflarE-KO;Tnfrsf1a-/- mice. RESULTS: CflarE-KO;Tnfrsf1a-/- mice were born but experienced severe dermatitis and succumbed soon after birth. CflarE-KO;Tnfrsf1a+/- mice exhibited embryonic lethality caused by massive keratinocyte apoptosis. Although keratinocytes from CflarE-KO;Tnfrsf1a-/- mice still died of apoptosis, neutralizing antibodies against Fas ligand and TNF-related apoptosis-inducing ligand substantially prolonged survival of CflarE-KO;Tnfrsf1a-/- mice. Expression of inflammatory cytokines, such as Il6 and Il17a was increased; conversely, expression of epidermal differentiation markers was severely downregulated in the skin of CflarE-KO;Tnfrsf1a-/- mice. Treatment of primary keratinocytes with IL-6 and, to a lesser extent, IL-17A suppressed expression of epidermal differentiation markers. CONCLUSION: TNF receptor superfamily 1 (TNFR1)-dependent or TNFR1-independent apoptosis of keratinocytes promotes inflammatory cytokine production, which subsequently blocks epidermal differentiation. Thus blockade of both TNFR1-dependent and TNFR1-independent cell death might be an alternative strategy to treat skin diseases when treatment with anti-TNF-α antibody alone is not sufficient.

1-Deoxynojirimycin (DNJ) Ameliorates Indomethacin-Induced Gastric Ulcer in Mice by Affecting NF-kappaB Signaling Pathway.

Gastric ulcer (GU) is a main threat to public health. 1-Deoxynojirimycin (DNJ) has antioxidant and anti-inflammatory properties and may prevent GU but related mechanism remains unclear. DNJ was extracted from the supernatants of Bacillus subtilis by using ethanol and purified by using CM-Sepharose chromatography. A GU mouse model was induced by indomethacin. The functional role of DNJ in GU mice was explored by measuring the main molecules in the NF-KappaB pathway. After the model establishment, 40 GU mice were evenly assigned into five categories: IG (received vehicle control), LG (10 µg DNJ daily), MG (20 µg DNJ daily), HG (40 µg DNJ daily), and RG (0.5 mg ranitidine daily). Meanwhile, eight healthy mice were assigned as a control group (CG). After 1-month therapy, weight and gastric volume were investigated. The levels of serum inflammatory cytokines (IL-6 and TNF-α), antioxidant indices [superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH)], and oxidant biomarker malondialdehyde (MDA) were examined via ELISA. Meanwhile, inflammatory cytokine (IL-6 and TNF-α) levels, and key molecules (NF-κB p65), cyclooxygenase 1 (COX-1 and COX2) involved in NF-κB pathway, were analyzed by using Western Blot. COX-1 and COX-2 levels were further measured by immunohistochemistry. The effects of DNJ on gastric functions were explored by measuring the changes of Motilin (MOT), Substance P (SP), Somatostatin (SS), and Vasoactive intestinal peptide (VIP) in GU mouse models with ELISA Kits. The results indicated that DNJ prevented indomethacin-caused increase of gastric volume. DNJ improved histopathology of GU mice when compared with the mice from IG group (P < 0.05). DNJ consumption decreased the levels of IL-6 and TNF-α (P < 0.05). DNJ increased antioxidant indices of GU mice by improving the activities of SOD, CAT and reduced GSH, and reduced MDA levels (P < 0.05). DNJ increased the levels of prostaglandin E2, COX-1, COX2, and reduced the levels of and NF-κB p65 (P < 0.05). DNJ showed protection for gastric functions of GU mice by reducing the levels of MOT and SP, and increasing the levels of SS and VIP. DNJ treatment inactivates NF-κB signaling pathway, and increases anti-ulceration ability of the models.

Root Extract of Polygonum cuspidatum Siebold & Zucc. Ameliorates DSS-Induced Ulcerative Colitis by Affecting NF-kappaB Signaling Pathway in a Mouse Model via Synergistic Effects of Polydatin, Resveratrol, and Emodin.

Background:Polygonum cuspidatum Siebold & Zucc. (PCS) has antibacterial properties and may prevent Ulcerative colitis (UC) but related molecular mechanism remains unknown. NF-κB signaling pathway is associated with inflammatory responses and its inactivation may be critical for effective therapy of UC. Methods: UC mouse (C57BL/6J) model was established by using dextran sulfate sodium (DSS). The extract of PCS (PCSE) was prepared by using ethanol and its main ingredients were measured by HPLC. Thirty-two UC mice were evenly assigned into DG (received vehicle control), LG (0.1 g/kg PCSE daily), MG (0.2 g/kg PCSE daily) and HG (0.4 g/kg PCSE daily) groups. Meanwhile, 8 healthy mice were assigned as a control group (CG). Serum pharmacokinetics of PCS was measured by using HPLC. After 8-day treatment, weight, colon length and disease activity index (DAI) were measured. Inflammatory cytokines and oxidant biomarkers were measured by ELISA kits. The levels of cytokines, and key molecules in NF-κB pathway, were measured by using Western Blot. The effects of main ingredients of PCSE on cytokines and NF-κB signaling pathway were explored by using intestinal cells of a mouse UC model. The normality criterion was evaluated using the Saphiro-Wilk test. The quantitative variables were compared using the paired Student's-t test. Results: The main ingredients of PCSE were polydatin, resveratrol and emodin. Polydatin may be transformed into resveratrol in the intestine of the mice. PCSE prevented DSS-caused weight loss and colon length reduction, and improved histopathology of UC mice (P < 0.05). PCSE treatment increased the serum levels of IL-10 and reduced the levels of IL-1 beta, IL-6 and TNF-α (P < 0.05). PCSE increased the activities of SOD, CAT, GPX and reduced the level of MDA, BCL-2, beta-arrestin, NF-κB p65 and the activity of MPO (P < 0.05). The combination of polydatin, resveratrol or emodin, and or PCSE exhibited higher inhibitory activities for cytokines and NF-κB signaling related molecules than any one of the three ingredients with same concentration treatment. Conclusion: Oral administration of PCSE suppressed NF-κB signaling pathway and exerts its anti-colitis effects via synergistic effects of polydatin, resveratrol or emodin.

Picroside II Shows Protective Functions for Severe Acute Pancreatitis in Rats by Preventing NF-κB-Dependent Autophagy.

Picroside II, from the herb Picrorhiza scrophulariiflora Pennell, has antioxidant and anti-inflammatory activities. However, its function on severe acute pancreatitis (SAP) and molecular mechanism remains unknown. The effects of picroside II on the SAP induced by cerulean were investigated. SAP rats were treated with picroside II (25 mg/kg). The severity of SAP was evaluated by using biochemical and histological analyses. Pancreatic cancer cell PANC-1 was transfected with ptfLC3 (an indicator of autophagic activity), pcDNA3.1-NF-κB (nuclear factor kappa B), and pTZU6+1-NF-κB-shRNA and then treated with picroside II. Relative molecules related with NF-κB-dependent autophagy were detected by using Western blot. Autophagic activities were observed by phase-contrast and fluorescent microscopes. Acetylated LC3 was detected by immunoprecipitation. The results showed that picroside II treatment reduced the level of ALT, AST, NF-κB, IL-1ß, IL-6, TNF-α, and SIRT1 (NAD+-dependent deacetylase) and increased the level of SOD and GSH. The autophagic activity was reduced when NF-κB was silenced, and the levels of TNF-α and SIRT1 were reduced. In contrast, the overexpression of NF-κB increased autophagic activity and the level of TNF-α, which activated SIRT1. SIRT1 deacetylated LC3 and increased autophagic activities. Picroside II ameliorates SAP by improving antioxidant and anti-inflammtory activities of SAP models via NF-κB-dependent autophagy.

Cellular FLICE-Inhibitory Protein Regulates Tissue Homeostasis.

Cellular FLICE-inhibitory protein (cFLIP) is structurally related to caspase-8, but lacks its protease activity. Cflip gene encodes several splicing variants including short form (cFLIPs) and long form (cFLIPL). cFLIPL is composed of two death effector domains at the N terminus and a C-terminal caspase-like domain, and cFLIPs lacks the caspase-like domain. Our studies reveal that cFLIP plays a central role in NF-κB-dependent survival signals that control apoptosis and programmed necrosis. Germline deletion of Cflip results in embryonic lethality due to enhanced apoptosis and programmed necrosis; however, the combined deletion of the death-signaling regulators, Fadd and Ripk3, prevents embryonic lethality in Cflip-deficient mice. Moreover, tissue-specific deletion of Cflip reveals cFLIP as a crucial regulator that maintains tissue homeostasis of immune cells, hepatocytes, intestinal epithelial cells, and epidermal cells by preventing apoptosis and programmed necrosis.

Depletion of myeloid cells exacerbates hepatitis and induces an aberrant increase in histone H3 in mouse serum.

Tissue-resident macrophages and bone marrow (BM)-derived monocytes play a crucial role in the maintenance of tissue homeostasis; however, their contribution to recovery from acute tissue injury is not fully understood. To address this issue, we generated an acute murine liver injury model using hepatocyte-specific Cflar-deficient (CflarHep-low ) mice. Cellular FLICE-inhibitory protein expression was down-regulated in Cflar-deficient hepatocytes, which thereby increased susceptibility of hepatocytes to death receptor-induced apoptosis. CflarHep-low mice developed acute hepatitis and recovered with clearance of apoptotic hepatocytes at 24 hours after injection of low doses of tumor necrosis factor α (TNFα), which could not induce hepatitis in wild-type (WT) mice. Depletion of Kupffer cells (KCs) by clodronate liposomes did not impair clearance of dying hepatocytes or exacerbate hepatitis in CflarHep-low mice. To elucidate the roles of BM-derived monocytes and neutrophils in clearance of apoptotic hepatocytes, we examined the effect of depletion of these cells on TNFα-induced hepatitis in CflarHep-low mice. We reconstituted CflarHep-low mice with BM cells from transgenic mice in which human diphtheria toxin receptor (DTR) was expressed under control of the lysozyme M (LysM) promoter. TNFα-induced infiltration of myeloid cells, including monocytes and neutrophils, was completely ablated in LysM-DTR BM-reconstituted CflarHep-low mice pretreated with diphtheria toxin, whereas KCs remained present in the livers. Under these experimental conditions, LysM-DTR BM-reconstituted CflarHep-low mice rapidly developed severe hepatitis and succumbed within several hours of TNFα injection. We found that serum interleukin-6 (IL-6), TNFα, and histone H3 were aberrantly increased in LysM-DTR BM-reconstituted, but not in WT BM-reconstituted, CflarHep-low mice following TNFα injection. CONCLUSION: These findings indicate an unexpected role of myeloid cells in decreasing serum IL-6, TNFα, and histone H3 levels via the suppression of TNFα-induced hepatocyte apoptosis. (Hepatology 2017;65:237-252).

A New Chinese Medicine Intestine Formula Greatly Improves the Effect of Aminosalicylate on Ulcerative Colitis.

Ulcerative colitis (UC) is a chronic lifelong inflammatory disorder of the colon. Current medical treatment of UC relies predominantly on the use of traditional drugs, including aminosalicylates, corticosteroids, and immunosuppressants, which failed to effectively control this disease's progression and produced various side effects. Here, we report a new Chinese medicine intestine formula (CIF) which greatly improved the effect of mesalazine, an aminosalicylate, on UC. In the present study, 60 patients with chronic UC were treated with oral mesalazine alone or in combination with CIF enema. The combination of mesalazine and CIF greatly and significantly improved the clinical symptoms and colon mucosal condition and improved the Mayo Clinic Disease Activity Index and health-related quality of life, when compared to mesalazine alone. In particular, the addition of CIF further decreased serum levels of tumor necrosis factor-alpha and hypersensitivity C-reactive protein but in contrast increased interleukin-4. Thus, the results demonstrate the beneficial role of CIF in UC treatment, which may be mediated by the regulation of inflammation.

Ursolic acid protects against ulcerative colitis via anti-inflammatory and antioxidant effects in mice.

Ursolic acid (UA) has been reported to have a protective effect in colitis. However, the underlying mechanisms remain to be elucidated. In the present study, experimental ulcerative colitis was induced in male BALB/c mice by the administration of 5% dextran sulfate sodium (DSS) for 7 days, followed by treatment with UA for another 7 days. Hematoxylin & eosin staining was performed to evaluate colon tissue damage, and enzyme assays were used to measure malondialdehyde (MDA) content and superoxide dismutase (SOD) activity in colon homogenate. In addition, serum levels of interleukin (IL)­1ß and tumor necrosis factor (TNF)­α were measured using an ELISA, and the level of nuclear factor (NF)­κB p65 in the colonic tissues was assessed by western blotting. The 7­day DSS administration induced marked colon damage, increased the serum levels of IL­1ß and TNF­α, increased MDA content and decreased SOD activity in the colon homogenate. These changes were significantly improved by treatment with UA. UA also reduced the DSS­stimulated high nuclear level of NF­κB p65 in the colon tissues. These results demonstrate a protective role of UA in ulcerative colitis, and suggest that anti-inflammatory and antioxidant activities are involved in the underlying mechanisms.

Effect of herbal formula xiao pi-II on functional dyspepsia.

OBJECTIVE: To investigate the therapeutic effect of the herbal medication Xiao Pi-II on the symptoms and gastric motility of patients with functional dysepsia (FD). METHODS: A total of 180 FD patients were divided randomly and equally into Xiao Pi-II and mosapride groups. The two groups were treated with Xiao Pi-II (100 mL, t.d.s., ante cibum) and mosapride (5 mg, t. d.s., ante cibum) for 2 weeks. Before treatment and 3 days after all medication was stopped, patients responded to a questionnaire evaluating gastrointestinal symptoms and were assessed with abdominal three dimensional ultrasonography (3D-US) for gastric motility. RESULTS: Gastrointestinal symptoms (especially bloating, post-prandial fullness and eructation) were improved significantly in FD patients treated with Xiao Pi-II (P < 0.05, P < 0.05, and P < 0.05), but no significant difference was found in the mosapride group (P > 0.05). The effective rates in the Xiao Pi-II and mosapride group were 86.7% and 60.0%, respectively (P < 0.05). The gastric liquid emptying rate (GLER) in the Xiao Pi-II group showed a significant increase (P < 0.01) after 2 weeks of treatment but there was no significant change (P > 0.05) of GLER in the mosapride group. CONCLUSION: Compared with mosapride, Xiao Pi-II improved symptoms and GLER significantly in FD patients with delayed gastric emptying.

c-FLIP maintains tissue homeostasis by preventing apoptosis and programmed necrosis.

As a catalytically inactive homolog of caspase-8, a proapoptotic initiator caspase, c-FLIP blocks apoptosis by binding to and inhibiting caspase-8. The transcription factor nuclear factor κB (NF-κB) plays a pivotal role in maintaining the homeostasis of the intestine and the liver by preventing death receptor-induced apoptosis, and c-FLIP plays a role in the NF-κB-dependent protection of cells from death receptor signaling. Because c-Flip-deficient mice die in utero, we generated conditional c-Flip-deficient mice to investigate the contribution of c-FLIP to homeostasis of the intestine and the liver at developmental and postnatal stages. Intestinal epithelial cell (IEC)- or hepatocyte-specific deletion of c-Flip resulted in perinatal lethality as a result of the enhanced apoptosis and programmed necrosis of the IECs and the hepatocytes. Deficiency in the gene encoding tumor necrosis factor-α (TNF-α) receptor 1 (Tnfr1) partially rescued perinatal lethality and the development of colitis in IEC-specific c-Flip-deficient mice but did not rescue perinatal lethality in hepatocyte-specific c-Flip-deficient mice. Moreover, adult mice with interferon (IFN)-inducible deficiency in c-Flip died from hepatitis soon after depletion of c-FLIP. Pretreatment of IFN-inducible c-Flip-deficient mice with a mixture of neutralizing antibodies against TNF-α, Fas ligand (FasL), and TNF-related apoptosis-inducing ligand (TRAIL) prevented hepatitis. Together, these results suggest that c-FLIP controls the homeostasis of IECs and hepatocytes by preventing cell death induced by TNF-α, FasL, and TRAIL.

Interleukin-11 links oxidative stress and compensatory proliferation.

Apoptotic cells can stimulate the compensatory proliferation of surrounding cells to maintain tissue homeostasis. Although oxidative stress is associated with apoptosis and necrosis, whether it contributes to compensatory proliferation is unknown. Here, we showed that interleukin-11 (IL-11), a member of the IL-6 family of proinflammatory cytokines, was produced by cells in an oxidative stress-dependent manner. IL-11 production depended on the activation in dying cells of extracellular signal-regulated kinase 2, which in turn caused the phosphorylation and accumulation of the transcription factor Fra-1 by preventing its proteasome-dependent degradation. Fra-1 was subsequently recruited to the Il11 promoter and activated gene transcription. Upon acute liver injury in mice, IL-11 was mainly produced by hepatocytes in response to reactive oxygen species that were presumably released from dying hepatocytes. IL-11 that was secreted by the dying cells then induced the phosphorylation of the transcription factor STAT3 in adjacent healthy hepatocytes, which resulted in their compensatory proliferation. Furthermore, an IL-11 receptor (IL-11R) agonist enhanced the proliferation of hepatocytes and ameliorated oxidative stress upon acetaminophen-induced liver injury. Conversely, the effects of acetaminophen were exacerbated in mice deficient in the IL-11R α subunit. Together, these results suggest that IL-11 provides a functional link between oxidative stress and compensatory proliferation.