Innate immune inflammatory cell death: PANoptosis and PANoptosomes in host defense and disease

Regulated cell death (RCD) triggered by innate immune activation is an important strategy for host survival during pathogen invasion and perturbations of cellular homeostasis. There are two main categories of RCD, including nonlytic and lytic pathways. Apoptosis is the most well-characterized nonlytic RCD, and the inflammatory pyroptosis and necroptosis pathways are among the best known lytic forms. While these were historically viewed as independent RCD pathways, extensive evidence of cross-talk among their molecular components created a knowledge gap in our mechanistic understanding of RCD and innate immune pathway components, which led to the identification of PANoptosis. PANoptosis is a unique innate immune inflammatory RCD pathway that is regulated by PANoptosome complexes upon sensing pathogens, pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs) or the cytokines produced downstream. Cytosolic innate immune sensors and regulators, such as ZBP1, AIM2 and RIPK1, promote the assembly of PANoptosomes to drive PANoptosis. In this review, we discuss the molecular components of the known PANoptosomes and highlight the mechanisms of PANoptosome assembly, activation and regulation identified to date. We also discuss how PANoptosomes and mutations in PANoptosome components are linked to diseases. Given the impact of RCD, and PANoptosis specifically, across the disease spectrum, improved understanding of PANoptosomes and their regulation will be critical for identifying new therapeutic targets and strategies.     

Antiproliferative activity and standardization of Tecomella undulata bark extract on K562 cells

Ethnopharmacological relevance

The bark of Tecomella undulata is primarily used in the treatment of syphilis, painful swellings and cancer by traditional healers. Also, it is claimed to be useful in treating urinary discharges, enlargement of spleen, leucorrhoea, leukoderma, tumors, liver disorders, gonorrhea, gout and promotes wound healing in Indian traditional system of medicine.

Aim

To establish a scientific validation for the antitumor effects of Tecomella undulata bark and explore the mechanistic pathway in chronic myeloid leukemia cell line, K562. The study was further extended to standardize the extract using quercetin as biomarker.

Methods

Induction of apoptosis by chloroform extract of Tecomella undulata bark (CTUB) was determined by MTT, Annexin V and caspase activation assays. The cell cycle analysis was done by flow cytometer and nuclear staining by DAPI. The standardization of the extract was performed through reverse phase-HPLC method under PDA detection.

Result

Results clearly showed the induction of apoptosis by CTUB in K562 cells. The effect was found to be dose dependent, having IC₅₀ of 30 μg/ml with activation of FAS, FADD, caspase 8, caspase 3/7 and fragmentation of DNA. The bioactive CTUB was determined to possess 0.03% (w/w) of quercetin.

Conclusion

The investigation clearly demonstrated the potential antitumor effect of CTUB, thereby validating the traditional claim. Quercetin, known to have anticancer activity is being reported and quantified for the first time from the bark of Tecomella undulata.     

缬草波春联合Caspases抑制剂诱导MKN45胃癌细胞凋亡

目的 研究中草药缬草提取物缬草波春联合Caspases抑制剂诱导MKN45胃癌细胞凋亡的作用。方法 将MKN45胃癌细胞分成4组:第1组加入同体积的生理盐水为对照;第2组分别加入浓度为10μM的Caspases-3、-8、-9抑制剂;第3组加入浓度为100 mg／L的缬草波春;第4组加入浓度为10 μM的Caspases-3、-8、-9抑制剂+浓度为100 mg／L的缬草波春混合物。药物作用24小时、48小时、72小时后,用流式细胞计分别检测凋亡率。结果　24、48、72小时作用后,第2组诱导MKN45细胞的凋亡率与对照组相似(P>0.05);第3组诱导MKN45细胞的凋亡率明显高于照组相(P<0.01);第4组中缬革波春联合Caspases-3、-9抑制剂诱导MKN45细胞的凋亡率均与对照组相似(P>0.05);缬草波存与Caspases-8抑制剂联合应用组诱导MKN45细胞的凋亡率明显高于对照组比(P<0.01),与第2组相似(P>0.05)。结论 缬草波春能诱导MKN45胃癌细胞凋亡,诱导凋亡能被Caspases-3、-9抑制剂抑制,Casoases-8抑制剂对缬草波春诱导的调亡无影响。     

Localization of apoptotic and proliferating cells and mRNA expression of caspases and Bcl-2 in gonads of chicken embryos

The aim of the present study was to analyze participation of apoptosis and proliferation in gonadal development in the chicken embryo by: (1) localization of apoptotic (TUNEL) and proliferating (PCNA immunoassay) cells in male and female gonads and (2) examination of mRNA expression (RT-PCR) of caspase-3, caspase-6 and Bcl-2 in the ovary and testis during the second half of embryogenesis and in newly hatched chickens. Apoptotic cells were found in gonads of both sexes. At E18 the percentage of apoptotic cells (the apoptotic index, AI) in the ovarian medulla and the testis was lower (p < 0.05) than in the ovarian cortex. In the ovarian medulla, the AI at E18 was lower (p < 0.05) than on E12. In the testis, the AI was significantly lower (p < 0.05) at E18 than at E15 and 1D. The percentage of proliferating cells (the proliferation index: PI) within the ovary significantly increased from E15 to 1D in the cortex, while proliferating cells in the medulla were detected only at E15. In the testis, the PI gradually increased from E12 to 1D. The mRNA expression of caspase-3 and -6 as well as Bcl-2 was detected in male and female gonads at days 12 (E12), 15 (E15) and 18 (E18) of embryogenesis and the day after hatching (1D). The expression of all analyzed genes on E12 was significantly higher (p < 0.05) in female than in male gonads. This difference was also observed at E15 and E18, but only for the caspase-6. The results obtained showed tissue- and sex-dependent differences in the number of apoptotic and proliferating cells as well as mRNA expression of caspase-3, -6 and Bcl-2 genes in the gonads of chicken embryos. Significant increase in the number of proliferating cells in the ovarian cortex and lack of these cells in the ovarian medulla (stages E12, E18, 1D) simultaneous with decrease in the intensity of apoptosis only in the medulla indicates that proliferation is the dominant process involved in the cortical development, which constitutes the majority of the functional structure of the fully developed ovary. No pronounced changes in the expression of apoptosis-related genes found during embryogenesis suggest that they cannot be considered as important indicators of gonad development. The molecular mechanisms of the regulation of balance between apoptosis and proliferation in developing avian gonads need to be further investigated.     

Active caspase 3 and DNA fragmentation as markers for apoptotic cell death in primary and metastatic liver tumours

AIMS: The induction of tumour cell death by apoptosis is a major goal of cancer therapy and the in situ detection of apoptosis in tumour tissue has become an important diagnostic parameter. Different apoptosis detection methods assess distinct biochemical processes in the dying cell. Thus, their direct comparison is mandatory to evaluate their diagnostic value. The aim of this study was to compare the immunohistochemical detection of active caspase 3 and single-stranded DNA in primary and metastatic liver tumours as markers of apoptotic cell death. METHODS: We studied detection of active caspase 3 and single-stranded DNA in 20 primary hepatocellular carcinomas (HCC) and 20 liver metastases from colorectal carcinomas (CRC) using immunohistochemistry on paraffin sections. RESULTS: Our results reveal that both methods are suitable and sensitive techniques for the in situ detection of apoptosis, however, they also demonstrate that immunohistochemistry for active caspase 3 and single-stranded DNA have differential sensitivities in HCC and CRC. CONCLUSION: The sensitivity of apoptosis detection using immunohistochemistry for active caspase 3 and single-stranded DNA may be tumour cell type dependent.     

Aspartame-induced apoptosis in PC12 cells

Aspartame is an artificial sweetner added to many low-calorie foods. The safety of aspartame remains controversial even though there are many studies on its risks. In this study, to understand the physiological effects of trace amounts of artificial sweetners on cells, the effects of aspartame on apoptosis were investigated using a PC12 cell system. In addition, the mechanism of apoptosis induced by aspartame in PC12 cells and effects on apoptotic factors such as cytochrome c, apoptosis-inducing factor, and caspase family proteins were studied by Western blotting and RT-PCR.Aspartame-induced apoptosis in PC12 cells in a dose-dependent manner. In addition, aspartame exposure increased the expressions of caspases 8 and 9, and cytochrome c. These results indicate that aspartame induces apoptosis mainly via mitochondrial pathway involved in apoptosis due to oxigen toxicity.     

Apoptotic mechanisms of the biotechnologically produced arylnaphtalene lignan justicidin B in the acute myeloid leukemia-derived cell line HL-60

BackgroundThe present study aimed at optimization of the biotechnological production of the lignan justicidin B by genetically transformed cultures of Linum leonii and the pharmacological evaluation of the pro-apoptotic effects of the compound in HL-60 cells.MethodsA rapidly growing selected root line of L. leonii was grown in 2-L bioreactor for period of 40 days and the protocols for obtaining of the compound have been optimized. The pharmacological study included evaluation of the cytotoxicity of the compound in HL-60 cells (MTT-assay), its apoptogenic effects and its effects on caspase 3,8 and 9 activation.ResultsAfter 40 days of sterile run scale up of hairy root culture in bioreactor, 27.2 g/L dry weight of root biomass was harvested from the bioreactor culture vessel, recording about nine times increase over initial inoculum (3.0 g), with 1.55% ± 0.07 Justicidin B, greater than yields from 300 ml flasks. Our findings are the first work toward the scale up of L. leonii hairy roots-based biotechnological production of Justicidin B, employing bioreactors for high biomass production to meet the industrial requirement. The results from the pharmacological evaluation have shown that the tested arylnaphtalene lignan is a potent cytotoxic and proapoptotic agent against HL-60. The induction of apoptosis proceeds via activation of the intrinsic mitochondrial cell-death signaling pathways.ConclusionThe potent activity at low micromolar concentration and the feasibility of biotechnological production of justicidin B implies that there is enormous scope in its further evaluation as possible antineoplastic drug candidate.     

Acute anoxia stimulates proliferation in adult neural stem cells from the rat brain

Hypoxic-ischemic damage is a major challenge for neuronal tissue. In the present study, we investigated the effects of anoxia and glucose deprivation on adult neural stem cells (NSCs) in vitro. We assessed glucose deprivation, anoxia and the combination of the latter separately. After 24 h of anoxia, cell numbers increased up to 60% compared to normoxic controls. Whereas nearly all normoxic cells incorporated the mitotic marker BrdU (99%), only 85% of the anoxic cells were BrdU-positive. Counting of interphase chromosomes showed 8-fold higher cell division activity after anoxia. The number of necrotic cells doubled after anoxia (14% compared to 7% after normoxia). Apoptosis was measured by two distinct caspases assays. Whereas the total caspase activity was reduced after anoxia, caspase 3/7 showed no alterations. Glucose deprivation and oxygen glucose deprivation both reduced cell viability by 56 and 53%, respectively. Under these conditions, total caspases activity doubled, but caspase 3/7 activity remained unchanged. Erythropoietin, which was reported as neuroprotective, did not increase cell viability in normoxia, but moderately under oxygen glucose deprivation by up to 6%. Erythropoietin reduced total caspase activity by nearly 30% under all the conditions, whereas caspase 3/7 activity was not affected. Our results show that anoxia increases proliferation and viability of adult NSCs, although a fraction of NSCs does not divide during anoxia. In conclusion, anoxia increased cell viability, cell number and proliferation in NSCs from the rat brain. Anoxia turned out to be a highly stimulating environmental for NSCs and NSCs died only when deprived of glucose. We conclude that the availability of glucose but not of oxygen is a crucial factor for NSC survival, regulating apoptotic pathways via caspases activity other than the caspases 3/7 pathway. Therefore, we conclude that NSCs are dying from glucose deprivation, not from hypoxic-ischemic damage.     

Induction of apoptosis in human hepatocarcinoma SMMC-7721 cells in vitro by flavonoids from Astragalus complanatus

Aim of the study

Flavonoids extracted from the seeds of Astragalus complanatus R.Br. reduce the proliferation of many cancer cells. The present study was carried out to evaluate the effects of these flavonoids from Astragalus complanatus (FAC) on human hepatocarcinoma cell viability and apoptosis and to investigate its mechanisms of action in SMMC-7721 cells.

Materials and methods

Cell viability was measured using the MTT assay. To detect apoptotic cells, SMMC-7721 cells treated with FAC were stained with Hoechst 33258 and subjected to agarose gel electrophoresis. Quantitative detection of apoptotic cells was performed by flow cytometry. The effects of FAC on apoptosis and cell cycle regulatory genes and proteins in SMMC-7721 cells were examined using an S series apoptosis and cell cycle gene array and Western blot analysis.

Results

The growth of SMMC-7721 and HepG2 cells was inhibited by treatment with FAC. Cell death induced by FAC was characterized by nuclear condensation and DNA fragmentation. Moreover, the cell cycle was arrested in the G0/G1 and S phases in FAC-treated SMMC-7721 cells. A sub-G1 peak with reduced DNA content was also formed. The activity of caspase-3 was significantly increased following FAC treatment. Microarray data indicated that the expression levels of 76 genes were changed in SMMC-7721 cells treated with FAC: 35 genes were up-regulated and 41 were down-regulated. Western blot analysis showed that caspase-3, caspase-8, Bax, P21, and P27 protein levels in SMMC-7721 cells were increased after 48 h of FAC treatment, while cyclinB1, cyclinD1, CDK1, and CDK4 protein levels were decreased.

Conclusions

These results suggest that FAC may play an important role in tumor growth suppression by inducing apoptosis in human hepatocarcinoma cells via mitochondria-dependent and death receptor-dependent apoptotic pathways.     

氨溴索对大鼠肝脏缺血再灌注损伤的保护作用

目的：探讨氨溴索对大鼠肝脏缺血再灌注损伤（I/RI）的保护作用及其机制。方法：18只雄性Wistar大鼠被随机均分为假手术组、肝I/RI模型组（模型组）、氨溴索预处理+肝I/RI模型组（氨溴索预处理组）。肝I/RI模型采用阻断入肝血流30 min后再灌注方法诱导,氨溴索预处理组于缺血前20 min尾静脉注射氨溴索（100 mg/kg）,而模型组给予等体积生理盐水。术后6 h处死大鼠,检测血清丙氨酸转氨酶（ALT）和天冬氨酸转氨酶（AST）水平和肝组织病理学改变,同时检测肝组织超氧化物岐化酶（SOD）,谷胱甘肽（GSH）,丙二醛（MDA）含量,caspase-3的活化水平。结果：与假手术组比较,模型组与氨溴索预处理组血清ALT和AST水平明显升高（均P<0.05）;肝组织出现明显的病理学改变;肝组织SOD和GSH含量明显下降,而MDA水平明显升高（均P<0.05）;肝组织caspase-3活化水平明显升高（均P<0.05）。与模型组比较,氨溴索预处理组以上各项指标的变化均明显减弱（均P<0.05）。结论：氨溴索预处理能减轻大鼠肝脏I/RI,机制可能与其调控抗氧化和抗凋亡信号通路有关。