Development of a fluorescence-based in vivo phagocytosis assay to measure mononuclear phagocyte system function in the rat

Abstract

The mononuclear phagocyte system (MPS) which provides protection against infection is made up of phagocytic cells that engulf and digest bacteria or other foreign substances. Suppression of the MPS may lead to decreased clearance of pathogenic microbes. Drug delivery systems and immunomodulatory therapeutics that target phagocytes have a potential to inhibit MPS function. Available methods to measure inhibition of MPS function use uptake of radioactively-labeled cells or labor-intensive semi-quantitative histologic techniques. The objective of this work was to develop a non-radioactive quantitative method to measure MPS function in vivo by administering heat-killed E. coli conjugated to a pH-sensitive fluorescent dye (Bioparticles®). Fluorescence of the Bioparticles® is increased at low pH when they are in phagocytic lysosomes. The amount of Bioparticles® phagocytosed by MPS organs in rats was determined by measuring fluorescence intensity in livers and spleens ex vivo using an IVIS® Spectrum Pre-clinical In Vivo Imaging System. Phagocytosis of the particles by peripheral blood neutrophils was measured by flow cytometry. To assess method sensitivity, compounds likely to suppress the MPS [clodronate-containing liposomes, carboxylate-modified latex particles, maleic vinyl ether (MVE) polymer] were administered to rats prior to injection of the Bioparticles®. The E. coli particles consistently co-localized with macrophage markers in the liver but not in the spleen. All of the compounds tested decreased phagocytosis in the liver, but had no consistent effects on phagocytic activity in the spleen. In addition, administration of clodronate liposomes and MVE polymer increased the percentage of peripheral blood neutrophils that phagocytosed the Bioparticles®. In conclusion, an in vivo rat model was developed that measures phagocytosis of E. coli particles in the liver and may be used to assess the impact of test compounds on MPS function. Still, the detection of inhibition of splenic macrophage function will require further assay development.     

Interleukin-10 secreted by B-1 cells modulates the phagocytic activity of murine macrophages in vitro

As demonstrated previously in our laboratory, B-1 cells migrate from the peritoneal cavity of mice and home to a distant site of inflammation to become macrophage-like cells. However, the influence that these cells might have on the kinetics and fate of the inflammatory process is not known. Considering that macrophages are pivotal in the inflammatory reaction, we decided to investigate the possible influence B-1 cells could have on macrophage activities in vitro. Our results show that peritoneal macrophages from Xid mice, a mouse strain deprived of B-1 cells, have higher phagocytic indexes for zymozan particles when compared with macrophages from wild-type mice. Moreover, macrophages from wild-type mice have a lower ability to release nitric oxide and hydrogen peroxide when compared with macrophages from Xid mice. Experiments using cocultures of B-1 cells and macrophages from Xid mice in transwell plates demonstrated that B-1 cells down-regulate macrophage activities. These observations also indicate that this phenomenon is not due to a physical interaction between these two cell populations. As B-1 cells are one of the main sources of interleukin (IL)-10, we demonstrate in this study that adherent peritoneal cells from Xid mice produce significantly less amounts of this cytokine in culture when compared with IL-10 production by cells from wild-type mice. When B-1 cells from IL-10 knock-out mice and macrophages from wild-type mice were cocultured in transwell plates, the phagocytic index of macrophages was not altered demonstrating that B-1 cells can influence the effector functions of macrophages in vitro via IL-10 secretion.     

Functional comparison of the mouse DC-SIGN, SIGNR1, SIGNR3 and Langerin, C-type lectins

The mouse (m) DC-SIGN family consists of several homologous type II transmembrane proteins located in close proximity on chromosome 8 and having a single carboxyl terminal carbohydrate recognition domain. We first used transfected non-macrophage cell lines to compare the polysaccharide and microbial uptake capacities of three of these lectins--DC-SIGN, SIGNR1 and SIGNR3--to another homologue mLangerin. Each molecule shares a potential mannose-recognition EPN-motif in its carbohydrate recognition domain. Using an anti-Tag antibody to follow Tag-labeled transfectants, we found that each molecule could be internalized, although the rates differed. However, mDC-SIGN was unable to take up FITC-dextran, FITC-ovalbumin, zymosan or heat-killed Candida albicans. The other three lectins showed distinct carbohydrate recognition properties, assessed by blocking FITC-dextran uptake at 37 degrees C and by mannan binding activity at 4 degrees C. Furthermore, only SIGNR1 was efficient in mediating the capture by transfected cells of Gram-negative bacteria, such as Escherichia coli and Salmonella typhimurium, while none of the lectins tested were competent to capture Gram-positive bacteria, Staphylococcus aureus. Interestingly, transfectants with SIGNR1 lacking the cytoplasmic domain were capable of binding FITC-zymosan in a manner that was abolished by EDTA or mannan, but not laminarin. In addition, resident peritoneal CD11b+ cells expressing SIGNR1 bound zymosan at 4 degrees C in concert with a laminarin-sensitive receptor. Therefore these homologous C-type lectins have distinct recognition patters for microbes despite similarities in the carbohydrate recognition domains.     

Human peritoneal B-1 cells and the influence of continuous ambulatory peritoneal dialysis on peritoneal and peripheral blood mononuclear cell (PBMC) composition and immunoglobulin levels

In mice, peritoneal B cells are composed of a unique B-1 cell population which can repopulate the intestinal lamina propria with IgA-producing cells, as well as contribute to the majority of serum IgM. In this study, peritoneal lymphocytes from patients starting continuous ambulatory peritoneal dialysis (CAPD) and from women undergoing bilateral tubal ligation (BTL) were analysed for the presence of a B-1 cell population as well as the expression of potential homing receptors. Up to 63% of the peritoneal B cells express surface antigen CD5, and most peritoneal lymphocytes express the mucosal homing receptors, α4β7 and αEβ7. When analysing serial samples collected from patients from the beginning of dialysis to 1 year, no marked changes were observed in serum or salivary immunoglobulin levels, although the peritoneal lymphocyte population was reduced by 50%. These data suggest that the phenotype of human peritoneal B-1 cells is similar to that of mice, but the contributions to the immune system may differ.     

Tumorigenicity and metastasization of sthe cells,with a low level of malignancy,during in vitro selection by peritoneal exudate cells

Laboratory of Antitumor Immunity, Research Institute of Carcinogenesis, All-Union Oncologic Scientific Center-Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Trapeznikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol 112, No. 11, pp. 525–529, November, 1991.     

人脐血单个核细胞静脉移植联合培哚普利对急性心肌梗死炎症反应的影响

背景：近期报道骨髓间充质干细胞心肌内直接移植联合培哚普利治疗急性心肌梗死大鼠,可改善心肌组织内环境,并增强急性心肌梗死疗效。 目的：观察人脐血单个核细胞静脉移植联合血管紧张素转化酶抑制剂培哚普利对家兔急性心肌梗死心肌组织炎症反应与促炎因子白细胞介素6表达及心功能影响,并探讨联合治疗对急性心肌梗死可能的保护机制。 方法：人脐血单个核细胞取自健康足月分娩产妇脐血。60只健康家兔制备急性心肌梗死模型,建模成功后随机数字表法均分对照组、培哚普利组、单纯移植组和联合治疗组。每组随机选5只家兔分别于移植后1,2,4周超声心动图检测家兔心功能指标左室射血分数及左室短轴缩短率;苏木精-伊红染色光镜观察心肌病理变化和白细胞计数;免疫组化检测心肌组织白细胞介素6蛋白表达量;荧光显微镜观测绿色荧光蛋白阳性细胞。 结果与结论：①与对照组比较,培哚普利组、单纯移植组、联合治疗组治疗后1,2,4周心功能指标左室短轴缩短率及左室射血分数改善(P < 0.05),单纯移植组高于培哚普利组(P < 0.05),联合治疗组改善最显著(P < 0.05)。②与对照组比较,培哚普利组、单纯移植组、联合治疗组治疗后1,2,4周心肌组织白细胞计数及白细胞介素6的表达均显著减低(P < 0.05),且单纯移植组低于培哚普利组(P < 0.05),联合治疗组最低(P < 0.05)。③联合治疗组、单纯移植组治疗后1,2,4周均可见绿色荧光蛋白阳性细胞散在分布于梗死周边区域,且联合治疗组细胞计数多于单纯移植组(P < 0.05)。说明培哚普利联合人脐血单个核细胞静脉移植治疗急性心肌梗死实验动物,能提高移植细胞在心肌组织内存活率,并进一步改善心功能。其机制可能与联合治疗抑制心肌局部炎症反应及促炎因子白细胞介素6水平表达作用增强有关。     

Microvesicular fat, inter cellular adhesion molecule-1 and regulatory T-lymphocytes are of importance for the inflammatory process in livers with non-alcoholic steatohepatitis

Great progress has been made in understanding the development of non-alcoholic fatty liver disease (NAFLD) but less is known about the mechanisms underlying the progress from steatosis to steatohepatitis (NASH). Our aim was to evaluate if the amount and type of storage of fat in hepatocytes is of importance for hepatocyte injury. We also wanted to show if not only the innate immunity but also the adaptive immunity is involved in NASH. Thirty-one patients with NASH or borderline NASH and 18 non-NASH patients were investigated. Liver biopsies were scored for NASH according to Kleiner et al. Paraffin-embedded liver biopsies were stained with antibodies against CD3, TLR4, CD68, Cleaved Caspase-3, ICAM1, Foxp3 and ApopTag by immunohistochemistry. Serum soluble ICAM-1 (sICAM-1) were analysed by ELISA. The volume density of fat was 59% in the NASH patients and microvesicular fat, increased in high NAS score patients. ICAM-1 positive hepatocytes were seen in NASH patients and were localized in areas with microvesicular fat. Non-NASH biopsies were negative for ICAM-1 positive hepatocytes. The sICAM-1 were significantly higher in NASH-patients (339.8 ± 34.07) than in non-NASH patients (229.5 ± 12.14), p = 0.0015. Patients with NAS score over four had higher area of CD68 positive cells p = 0.0011 and Foxp3 positive cells (p = 0.024) than non-NASH patients. In liver tissue with NASH, hepatocytes with microvesicular steatosis seem to be expressing more inflammatory markers, and in this liver tissue an increased number of CD68 cells and regulatory T-cells (Tregs, e.g. Foxp3+ cells) were seen, indicating an involvement of, both the innate and the adaptive immunity.     

Defining the anatomical localisation of subsets of the murine mononuclear phagocyte system using integrin alpha X (Itgax, CD11c) and colony stimulating factor 1 receptor (Csf1r, CD115) expression fails to discriminate dendritic cells from macrophages

The murine mononuclear phagocyte (MNP) system comprises a diverse population of cells, including monocytes, dendritic cells (DC) and macrophages. Derived from the myeloid haematopoietic lineage, this group of cells express a variety of well characterized surface markers. Expression of the integrin alpha X (Itgax, CD11c) is commonly used to identify classical DC, and similarly expression of colony stimulating factor 1 receptor (Csf1r, CD115) to identify macrophages. We have characterized the expression of these markers using a variety of transgenic mouse models. We confirmed previous observations of Itgax expression in anatomically defined subsets of MNPs in secondary lymphoid organs, including all MNPs identified within the germinal centres. The majority of MNPs in the intestinal lamina propria and lung express Itgax. All mucosal Itgax expressing cells also express Csf1r suggesting Csf1-dependent haematopoietic derivation. This double-positive population included germinal centre MNPs. These data reveal that Itgax expression alone does not specifically define classical DC. These results suggest more cautious interpretation of Itgax-dependent experimentation and direct equation with uniquely DC-mediated activities, particularly in the functioning of non-lymphoid MNPs within the intestinal lamina propria.     

SIGN-R1, a novel C-type lectin expressed by marginal zone macrophages in spleen,mediates uptake of the polysaccharide dextran

The marginal zone macrophages of the spleen are implicated in the clearance of polysaccharides, but underlying mechanisms need to be pinpointed. SIGN-R1 is one of five recently identified mouse genes that are homologous to human DC-SIGN and encode a single, external, C-terminal C-type lectin domain. We find that a polyclonal antibody to a specific SIGN-R1 peptide reacts primarily and strongly with a subset of macrophages in the marginal zone of spleen and lymph node medulla. In both sites, SIGN-R1 exists primarily in an aggregated form, resistant to dissociation into monomers upon boiling in SDS under reducing conditions. Upon transfection into three different cell lines, high-mol.-wt forms bearing SIGN-R1 are expressed, as well as reactivity with ER-TR9, a mAb previously described to react selectively with marginal zone macrophages. SIGN-R1-expressing macrophages preferentially sequester dextrans following i.v. injection. Likewise, when phagocytic cells are enriched from spleen and tested in culture, dextran is selectively endocytosed by a subset of very large SIGN-R1(+) cells representing approximately 5% of total released macrophages. Uptake of FITC-dextran by these macrophages in vivo and in vitro is blocked by ER-TR9 and polyclonal anti-SIGN-R1 antibodies. Following transfection with SIGN-R1, cell lines become competent to endocytose dextrans. The dextran localizes primarily to compartments lacking transferrin receptor and the LAMP-1 CD107a panlysosomal antigen. Therefore, SIGN-R1 mediates the uptake of dextran polysaccharides, and it is predominantly expressed in the macrophages of the splenic marginal zone and lymph node medulla.     

Pulmonary response to surface-coated nanotitanium dioxide particles includes induction of acute phase response genes, inflammatory cascades, and changes in microRNAs: a toxicogenomic study

Titanium dioxide nanoparticles (nanoTiO(2) ) are used in various applications including in paints. NanoTiO(2) inhalation may induce pulmonary toxicity and systemic effects. However, the underlying molecular mechanisms are poorly understood. In this study, the effects of inhaled surface-coated nanoTiO(2) on pulmonary global messenger RNA (mRNA) and microRNA (miRNA) expression in mouse were characterized to provide insight into the molecular response. Female C57BL/6BomTac mice were exposed for 1 hr daily to 42.4 ± 2.9 (SEM) mg surface-coated nanoTiO(2) /m(3) for 11 consecutive days by inhalation and were sacrificed 5 days following the last exposure. Physicochemical properties of the particles were determined. Pulmonary response to nanoTiO(2) was characterized using DNA microarrays and pathway-specific PCR arrays and related to data on pulmonary inflammation from bronchial lavages. NanoTiO(2) exposure resulted in increased levels of mRNA for acute phase markers serum amyloid A-1 (Saa1) and serum amyloid A-3 (Saa3), several C-X-C and C-C motif chemokines, and cytokine tumor necrosis factor genes. Protein analysis of Saa1 and 3 showed selective upregulation of Saa3 in lung tissues. Sixteen miRNAs were induced by more than 1.2-fold (adjusted P-value < 0.05) following exposure. Real time polymerase chain reaction confirmed the upregulation of miR-1, miR-449a and revealed dramatic induction of miR-135b (60-fold). Thus, inhalation of surface-coated nanoTiO(2) results in changes in the expression of genes associated with acute phase, inflammation and immune response 5 days post exposure with concomitant changes in several miRNAs. The role of these miRNAs in pulmonary response to inhaled particles is unknown and warrants further research.     

人脐血单个核细胞移植治疗急性一氧化碳中毒后迟发脑病1年随访

背景：研究报道在特定的体内外环境下,脐血间充质干细胞能够诱导分化成为包括神经干细胞在内的多种组织细胞。 目的：评价人脐血单个核细胞经腰穿途径移植后治疗急性一氧化碳中毒后迟发性脑病的疗效及安全性。 方法：一氧化碳中毒后迟发性脑病患者60例随机分为2组。对照组给予高压氧及药物治疗;治疗组采用鞘内注射法将经密度梯度离心法分离出的人脐血单个核细胞移植到一氧化碳中毒性脑病患者的蛛网膜下腔,余治疗方法同对照组。分别于人脐血单个核细胞移植前、移植后3,9,12个月对患者进行简易精神状态检查法、改良Asworth肌肉痉挛程度分级及日常生活量表评分检查;比较两组患者MRI变化;同时对随诊患者行胸片、心电图及血生化检查,客观评价人脐血单个核细胞移植的安全性。 结果与结论：人脐血单个核细胞移植3,9,12个月,治疗组Asworth肌肉痉挛程度分级评分均显著低于对照组(P=0.032);移植后9,12个月简易智力状况检查法及日常生活量表评分均显著高于对照组(P < 0.05);两组患者神经功能在各时间点的变化趋势相似。人脐血单个核细胞移植后12个月MRI检查结果显示,治疗组患者MRI改善程度较对照组明显。提示鞘内注射移植人脐血单个核细胞治疗一氧化碳中毒后迟发脑病疗效优于高压氧治疗。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

Contribution of tumor necrosis factor α and interleukin-1 α on the production of macrophage inflammatory protein-2 in response to respiratory syncytial virus infection in a murine macrophage cell line,RAW264.7

The production of several inflammatory cytokines, such as murine macrophage inflammatory protein-2 (MIP-2), tumor necrosis factor (TNF), and interleukin (IL)-1, was investigated in response to respiratory syncytial virus (RSV) infection in a murine macrophage cell line, RAW264.7, with special reference to mutual relation of their productions. The kinetics of MIP-2 production showed a trend for a biphasic pattern, that is, MIP-2 levels became detectable from 2 h postinfection (p.i.) and increased markedly until 8 h p.i. Thereafter, this level fell to the same level until 16 h p.i. and then increased again. TNF α was also detectable at 2 h p.i. and then increased sharply until 8 h p.i., when the peak level attained. Compared with the levels of MIP-2 and TNF α, that of IL-1 α/β, especially IL-1 β, was lower (ng versus pg/ml order). The presence of anti-TNF α or anti-IL-1 α antibody did not influence the early phase of MIP-2 production but significantly inhibited the late phase, suggesting that MIP-2 is induced by the combined effects of RSV infection via direct induction and indirectly after initial induction of TNF α and IL-1 α productions. Although RSV-infected RAW264.7 cells had no alteration inviability compared with mock-infected control, these data demonstrate that RSV is a potent inducer of inflammatory cytokines by direct induction and indirectly via the initial production of other cytokines. J. Med. Virol. 53:145–149, 1997. © 1997 Wiley-Liss, Inc.     

Serological and cellular definition of a new HLA-DR associated determinant, MC1, and its association with rheumatoid arthritis

A new serological HLA-DR associated determinant was defined by a cluster of six B cell alloantisera. This determinant, designated as MC1, was strongly associated with DR1 and DR4 and appeared unrelated to MB, MT, and SB. The antigen frequency of MC1 was 47% in Caucasoids and 43% in Blacks. Mixed leukocyte culture cloning yielded an alloreactive T cell clone with PLT specificity associated with MC1. We have also observed that certain alloreactive clones may also acquire expression of MC1 but not DR4 during long-term culture maintenance in the presence of DR4, MC1-positive feeder cells. Disease association studies showed a significantly increased frequency of MC1 in adult rheumatoid arthritis patients (93.5% vs 47.4% in normals; relative risk 16.1). These findings suggest that MC1 represents a novel HLA-D encoded determinant.     

Liposomes of phosphatidylcholine and cholesterol induce an M2-like macrophage phenotype reprogrammable to M1 pattern with the involvement of B-1 cells

Macrophages respond to endogenous and non-self stimuli acquiring the M1 or M2 phenotypes, corresponding to classical or alternative activation, respectively. The role of B-1 cells in the regulation of macrophage polarization through the secretion of interleukin (IL)-10 has been demonstrated. However, the influence of B-1 cells on macrophage phenotype induction by an immunogen that suppress their ability to secrete IL-10 has not been explored. Here, we studied the peritoneal macrophage pattern induced by liposomes comprised of dipalmitoylphosphatidylcholine (DPPC) and cholesterol (Chol) carrying ovalbumin (OVA) (Lp DPPC/OVA), and the involvement of B-1 cells in macrophage polarization. Peritoneal cells from BALB/c, B-1 cells-deficient BALB/xid and C57BL/6 mice immunized with Lp DPPC/OVA and OVA in soluble form (PBS/OVA) were analyzed and stimulated or not in vitro with lipopolysaccharide (LPS). Peritoneal macrophages from BALB/c and C57BL/6 mice immunized with Lp DPPC/OVA showed an M2-like phenotype as evidenced by their high arginase activity without LPS stimulation. Upon stimulation, these macrophages were reprogrammable toward the M1 phenotype with the upregulation of nitric oxide (NO) and a decrease in IL-10 secretion. In addition, high IFN-γ levels were detected in the culture supernatant of peritoneal cells from BALB/c and C57BL/6 mice immunized with Lp DPPC/OVA. Nevertheless, still high levels of arginase activity and undetectable levels of IL-12 were found, indicating that the switch to a classical activation state was not complete. In the peritoneal cells from liposomes-immunized BALB/xid mice, levels of arginase activity, NO, and IL-6 were below those from wild type animals, but the last two products were restored upon adoptive transfer of B-1 cells, together with an increase in IFN-γ secretion. Summarizing, we have demonstrated that Lp DPPC/OVA induce an M2-like pattern in peritoneal macrophages reprogrammable to M1 phenotype after LPS stimulation, with the involvement of B-1 cells.     

C1q,a subunit of the first component of complement,enhances antibody-mediated apoptosis of cultured rat glomerular mesangial cells

We have shown previously that IgG2a anti-Thy-1 MoAb (ER4G) induces apoptosis of rat mesangial cells (GMC) in vitro. Since the classical complement pathway plays an essential role in Thy-1 nephritis, we analysed whether C1q, a subunit of the first component of complement, enhances the ER4G-mediated apoptosis of rat GMC. Two different subclasses of anti-Thy-1 MoAb, ER4G (IgG2a) and ER14 (IgG1), were used. It was established that ER4G binds C1q efficiently, while ER14 reacts poorly with C1q. For the experiments of apoptosis, quiescent rat GMC were exposed for 1 h at 37°C to a fixed concentration of anti-Thy-1 MoAb and incubated further for 16 h at 37°C in the presence or absence of C1q. GMC exposed to medium (M-GMC) followed by incubation of the cells with medium alone was used as controls. Apoptosis was assessed by morphological studies and quantitative analysis on FACS using FITC-annexin V (the annexin V methods) or bicolour FACS analysis using FITC-annexin V and propidium iodide (the annexin V/PI method). With the annexin V method, M-GMC revealed 9.4 ± 1.4% apoptosis. C1q had only marginal effects on apoptosis of M-GMC. GMC exposed to ER4G (ER4G-GMC) and further incubated with medium in the absence of C1q resulted in 25.7 ± 5.7% apoptosis (P < 0.01 relative to control). Incubation of ER4G-GMC together with 100 μg/ml of C1q significantly increased GMC-apoptosis up to 39.4 ± 4.9% (P < 0.01 relative to ER4G-GMC incubated in the absence of C1q). This enhancing effect of C1q on apoptosis of ER4G-GMC was time- and dose-dependent. In contrast, C1q did not significantly alter the apoptosis of either GMC exposed to ER14 (ER14-GMC) or to F(ab′)₂-ER4G (F(ab′)₂-ER4G-GMC), while ER14-GMC or F(ab′)₂-ER4G-GMC incubated with medium resulted in significant apoptosis compared with control. These results were supported by morphological studies and bicolour FACS analyses in time course experiments using the annexin V/PI method. The effect of C1q is dependent on the presence of intact C1q-containing globular heads and does not occur with collagen-like fragments of C1q. Furthermore, incubation of ER4G-GMC with anti-mouse κ-chain antibodies also increased ER4G-mediated GMC-apoptosis. These results indicate for the first time that C1q enhances antibody-mediated apoptosis of rat GMC in vitro, presumably by its binding to ER4G and probably by additional cross-linking of Thy-1 on the surface of GMC.     

PYNOD, a novel Apaf-1/CED4-like protein is an inhibitor of ASC and caspase-1

Recently, a large subfamily of nucleotide-binding and oligomerization domain-containing proteins that have an N-terminal pyrin-like domain and C-terminal leucine-rich repeats has been described. In this study, we identified PYNOD, a novel member of this family that lacks the leucine-rich repeats. We found that human PYNOD mRNA is expressed in various tissues and at high levels in heart, skeletal muscle and brain. It is also expressed in various cell lines, including haematopoietic cell lines. PYNOD oligomerizes and binds to ASC, an adaptor protein that plays a role in apoptotic and inflammatory signal transduction, and to caspase-1 and IL-1beta. PYNOD inhibits apoptosis-associated speck-like protein containing a CARD (ASC)-mediated NF-kappaB activation and apoptosis, and caspase-1-mediated IL-1beta maturation, and it does so in the presence and absence of constitutively active mutants of CARD12 and PYPAF1, which are enhancers of these processes. Thus, PYNOD is a novel regulator of apoptosis and inflammation.