Gasdermins gone wild: new roles for GSDMs in regulating cellular homeostasis

Pulmonary damage induction upon Acrylic amide exposure via activating miRNA-223-3p and miRNA-325-3p inflammasome/pyroptosis and fibrosis signaling pathway: New mechanistic approaches of A green-synthesized extract

Exposure to acrylic amide (AD) has garnered worldwide attention due to its potential adverse health effects, prompting calls from the World Health Organization for intensified research into associated risks. Despite this, the relationship between oral acrylic amide (acrylamide) (AD) exposure and pulmonary dysfunction remains poorly understood. Our study aimed to investigate the correlation between internal oral exposure to AD and the decline in lung function, while exploring potential mediating factors such as tissue inflammation, oxidative stress, pyroptosis, and apoptosis. Additionally, we aimed to evaluate the potential protective effect of zinc oxide nanoparticles green-synthesized moringa extract (ZNO-MONPs) (10 mg/kg b.wt) against ACR toxicity and conducted comprehensive miRNA expression profiling to uncover novel targets and mechanisms of AD toxicity (miRNA 223-3 P and miRNA 325-3 P). Furthermore, we employed computational techniques to predict the interactions between acrylic amide and/or MO-extract components and tissue proteins. Using a rat model, we exposed animals to oral acrylamide (20 mg/kg b.wt for 2 months). Our findings revealed that AD significantly downregulated the expression of miRNA 223-3 P and miRNA 325-3 P, targeting NLRP-3 & GSDMD, respectively, indicating the induction of pyroptosis in pulmonary tissue via an inflammasome activating pathway. Moreover, AD exposure resulted in lipid peroxidative damage and reduced levels of GPX, CAT, GSH, and GSSG. Notably, AD exposure upregulated apoptotic, pyroptotic, and inflammatory genes, accompanied by histopathological damage in lung tissue. Immunohistochemical and immunofluorescence techniques detected elevated levels of indicative harmful proteins including vimentin and 4HNE. Conversely, concurrent administration of ZNO-MONPs with AD significantly elevated the expression of miRNA 223-3 P and miRNA 325-3 P, protecting against oxidative stress, apoptosis, pyroptosis, inflammation, and fibrosis in rat lungs. In conclusion, our study highlights the efficacy of ZNO-MONPs NPs in protecting pulmonary tissue against the detrimental impacts of foodborne toxin AD.

Gasdermin-B (GSDMB) takes center stage in antibacterial defense, inflammatory diseases, and cancer

One of the hottest topics in biomedical research is to decipher the functional implications of the Gasdermin (GSDM) protein family in human pathologies. These proteins are the key effectors of a lytic and pro-inflammatory cell death type termed pyroptosis (also known as "Gasdermin-mediated programmed cell death"). However, ever-growing evidence showed that GSDMs can play multiple and complex roles in a context-dependent manner. In this sense, Gasdermin-B (GSDMB; the only GSDM gene absent in mice and rats) has been implicated in antibacterial defense, numerous inflammatory pathologies (e.g., asthma, ulcerative colitis), and cancer, but both cell death-dependent and -independent functions have been reported in these diseases, fueling the debate on whether GSDMB has genuine pyroptotic capacity. Recently, a series of seminal papers cast light on the GSDMB multitasking capacity by showing that different GSDMB transcriptional isoforms have distinct biological activities. Nonetheless, there are still obscure areas to be clarified on the precise functional involvement of GSDMB translated variants in physiological and pathological conditions. In this viewpoint, we critically discuss the most recent and exciting data on this topic and propose a series of relevant challenges that need to be overcome before GSDMB-driven biomedical applications (as a biomarker of disease risk/progression/outcome or as specific therapeutic target) become a reality in clinical settings.

Conformational Switch of a Peptide Provides a Novel Strategy to Design Peptide Loaded Porous Organic Polymer for Pyroptosis Pathway Mediated Cancer Therapy

While peptide-based drug development is extensively explored, this strategy has limitations due to rapid excretion from the body (or shorter half-life in the body) and vulnerability to protease-mediated degradation. To overcome these limitations, a novel strategy for the development of a peptide-based anticancer agent is introduced, utilizing the conformation switch property of a chameleon sequence stretch (PEP1) derived from a mycobacterium secretory protein, MPT63. The selected peptide is then loaded into a new porous organic polymer (PG-DFC-POP) synthesized using phloroglucinol and a cresol derivative via a condensation reaction to deliver the peptide selectively to cancer cells. Utilizing ensemble and single-molecule approaches, this peptide undergoes a transition from a disordered to an alpha-helical conformation, triggered by the acidic environment within cancer cells that is demonstrated. This adopted alpha-helical conformation resulted in the formation of proteolysis-resistant oligomers, which showed efficient membrane pore-forming activity selectively for negatively charged phospholipids accumulated in cancer cell membranes. The experimental results demonstrated that the peptide-loaded PG-DFC-POP-PEP1 exhibited significant cytotoxicity in cancer cells, leading to cell death through the Pyroptosis pathway, which is established by monitoring numerous associated events starting from lysosome membrane damage to GSDMD-induced cell membrane demolition. This novel conformational switch-based drug design strategy is believed to have great potential in endogenous environment-responsive cancer therapy and the development of future drug candidates to mitigate cancers.

Pyroptosis: A spoiler of peaceful coexistence between cells in degenerative bone and joint diseases

BACKGROUND

As people age, degenerative bone and joint diseases (DBJDs) become more prevalent. When middle-aged and elderly people are diagnosed with one or more disorders such as osteoporosis (OP), osteoarthritis (OA), and intervertebral disc degeneration (IVDD), it often signals the onset of prolonged pain and reduced functionality. Chronic inflammation has been identified as the underlying cause of various degenerative diseases, including DBJDs. Recently, excessive activation of pyroptosis, a form of programed cell death (PCD) mediated by inflammasomes, has emerged as a primary driver of harmful chronic inflammation. Consequently, pyroptosis has become a potential target for preventing and treating DBJDs.

AIM OF REVIEW

This review explored the physiological and pathological roles of the pyroptosis pathway in bone and joint development and its relation to DBJDs. Meanwhile, it elaborated the molecular mechanisms of pyroptosis within individual cell types in the bone marrow and joints, as well as the interplay among different cell types in the context of DBJDs. Furthermore, this review presented the latest compelling evidence supporting the idea of regulating the pyroptosis pathway for DBJDs treatment, and discussed the potential, limitations, and challenges of various therapeutic strategies involving pyroptosis regulation.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In summary, an interesting identity for the unregulated pyroptosis pathway in the context of DBJDs was proposed in this review, which was undertaken as a spoiler of peaceful coexistence between cells in a degenerative environment. Over the extended course of DBJDs, pyroptosis pathway perpetuated its activity through crosstalk among pyroptosis cascades in different cell types, thus exacerbating the inflammatory environment throughout the entire bone marrow and joint degeneration environment. Correspondingly, pyroptosis regulation therapy emerged as a promising option for clinical treatment of DBJDs.

Cell Membrane Perforation: Patterns, Mechanisms and Functions

Cell membrane is crucial for the cellular activities, and any disruption to it may affect the cells. It is demonstrated that cell membrane perforation is associated with some biological processes like programmed cell death (PCD) and infection of pathogens. Specific developments make it a promising technique to perforate the cell membrane controllably and precisely. The pores on the cell membrane provide direct pathways for the entry and exit of substances, and can also cause cell death, which means reasonable utilization of cell membrane perforation is able to assist intracellular delivery, eliminate diseased or cancerous cells, and bring about other benefits. This review classifies the patterns of cell membrane perforation based on the mechanisms into 1) physical patterns, 2) biological patterns, and 3) chemical patterns, introduces the characterization methods and then summarizes the functions according to the characteristics of reversible and irreversible pores, with the aim of providing a comprehensive summary of the knowledge related to cell membrane perforation and enlightening broad applications in biomedical science.

Induction of IFIT1/IFIT3 and inhibition of Bcl-2 orchestrate the treatment of myeloma and leukemia via pyroptosis

Induction of pyroptosis is proposed as a promising strategy for the treatment of hematological malignancies, but little is known. In the present study, we find clioquinol (CLQ), an anti-parasitic drug, induces striking myeloma and leukemia cell pyroptosis on a drug screen. RNA sequencing reveals that the interferon-inducible genes IFIT1 and IFIT3 are markedly upregulated and are essential for CLQ-induced GSDME activation and cell pyroptosis. Specifically, IFIT1 and IFIT3 form a complex with BAX and N-GSDME therefore directing N-GSDME translocalization to mitochondria and increasing mitochondrial membrane permeabilization and triggering pyroptosis. Furthermore, venetoclax, an activator of BAX and an inhibitor of Bcl-2, displays strikingly synergistic effects with CLQ against leukemia and myeloma via pyroptosis. This study thus reveals a novel mechanism for mitochondrial GSDME in pyroptosis and it also illustrates that induction of IFIT1/T3 and inhibition of Bcl-2 orchestrate the treatment of leukemia and myeloma via pyroptosis.

Gasdermin D regulates soluble fms-like tyrosine kinase 1 release in macrophages

Preeclampsia (PE) is a serious complication, and soluble fms-like tyrosine kinase (sFLT1) released from the placenta is one of the causes of PE pathology. Trophoblasts are the primary source of sFLT1; however, monocytes/macrophages exist enough in the placenta can also secrete sFLT1. Sterile inflammatory responses, especially NLRP3 inflammasome and its downstream gasdermin D (GSDMD)-regulated pyroptosis, may be involved in the development of PE pathology. In this study, we investigated whether human monocyte/macrophage cell line THP-1 cells secrete sFLT1 depending on the NLRP3 inflammasome and GSDMD. To differentiate THP-1 monocytes into macrophages, treatment with phorbol 12-myristate 13-acetate (PMA) induced sFLT1 with interleukin (IL)- 1β, but did not induce cell lytic death. IL-1β secretion induced by PMA inhibited by deletion of NLRP3 and inhibitors of NLRP3 and caspase-1, but deletion of NLRP3 and these inhibitors did not affect sFLT1 secretion in THP-1 cells. Both gene deletion and inhibition of GSDMD dramatically decreased IL-1β and sFLT1 secretion from THP-1 cells. Treatment with CA074-ME (a cathepsin B inhibitor) also reduced the secretion of both sFLT1 and IL-1β in THP-1 cells. In conclusion, THP-1 macrophages release sFLT1 in a GSDMD-dependent manner, but not in the NLRP3 inflammasome-dependent manner, and this sFLT1 release may be associated with the non-lytic role of GSDMD. In addition, sFLT1 levels induced by PMA are associated with lysosomal cathepsin B in THP-1 macrophages. We suggest that sFLT1 synthesis regulated by GSDMD are involved in the pathology of PE.

Using CRISPR-Cas9/phosphoproteomics to identify substrates of calcium/calmodulin-dependent kinase 2δ

Ca2+/Calmodulin-dependent protein kinase 2 (CAMK2) family proteins are involved in the regulation of cellular processes in a variety of tissues including brain, heart, liver, and kidney. One member, CAMK2δ (CAMK2D), has been proposed to be involved in vasopressin signaling in the renal collecting duct, which controls water excretion through regulation of the water channel aquaporin-2 (AQP2). To identify CAMK2D target proteins in renal collecting duct cells (mpkCCD), we deleted Camk2d and carried out LC-MS/MS-based quantitative phosphoproteomics. Specifically, we used CRISPR/Cas9 with two different guide RNAs targeting the CAMK2D catalytic domain to create multiple CAMK2D KO cell lines. AQP2 protein abundance was lower in the CAMK2D KO cells than in CAMK2D-intact controls. AQP2 phosphorylation at Ser256 and Ser269 (normalized for total AQP2) was decreased. However, trafficking of AQP2 to and from the apical plasma membrane was sustained. Large-scale quantitative phosphoproteomic analysis (TMT-labeling) in the presence of the vasopressin analog dDAVP (0.1 nM, 30 min) allowed quantification of 11,570 phosphosites of which 169 were significantly decreased, while 206 were increased in abundance in CAMK2D KO clones. These data are available for browsing or download at https://esbl.nhlbi.nih.gov/Databases/CAMK2D-proteome/. Motif analysis of the decreased phosphorylation sites revealed a target preference of -(R/K)-X-X-p(S/T)-X-(D/E), matching the motif identified in previous in vitro phosphorylation studies using recombinant CAMK2D. Thirty five of the significantly downregulated phosphorylation sites in CAMK2D KO cells had exactly this motif and are judged to be likely direct CAMK2D targets. This adds to the list of known CAMK2D target proteins found in prior reductionist studies.

Toxoplasma gondii Induces Pyroptosis in Human Placental Trophoblast and Amniotic Cells by Inducing ROS Production and Activation of Cathepsin B and NLRP1/NLRP3/NLRC4/AIM2 Inflammasome

Toxoplasma gondii infection in pregnant women may cause fetal anomalies; however, the underlying mechanisms remain unclear. The current study investigated whether T. gondii induces pyroptosis in human placental cells and the underlying mechanisms. Human placental trophoblast (BeWo and HTR-8/SVneo) and amniotic (WISH) cells were infected with T. gondii, and then reactive oxygen species (ROS) production, cathepsin B (CatB) release, inflammasome activation, and pyroptosis induction were evaluated. The molecular mechanisms of these effects were investigated by treating the cells with ROS scavengers, a CatB inhibitor, or inflammasome-specific siRNA. T. gondii infection induced ROS generation and CatB release into the cytosol in placental cells but decreased mitochondrial membrane potential. T. gondii-infected human placental cells and villi exhibited NLRP1, NLRP3, NLRC4, and AIM2 inflammasome activation and subsequent pyroptosis induction, as evidenced by increased expression of ASC, cleaved caspase-1, and mature IL-1β and gasdermin D cleavage. In addition to inflammasome activation and pyroptosis induction, adverse pregnancy outcome was shown in a T. gondii-infected pregnant mouse model. Administration of ROS scavengers, CatB inhibitor, or inflammasome-specific siRNA into T. gondii-infected cells reversed these effects. Collectively, these findings show that T. gondii induces NLRP1/NLRP3/NLRC4/AIM2 inflammasome-dependent caspase-1-mediated pyroptosis via induction of ROS production and CatB activation in placental cells. This mechanism may play an important role in inducing cell injury in congenital toxoplasmosis.

Structural and functional insights into GSDMB isoforms complex roles in pathogenesis

SHADSGasdermins (GSDMs) have garnered significant scientific interest due to their protective and detrimental roles in innate immunity, host defense, inflammation, and cancer alongside with other pathologies. While GSDMs are mostly recognized as key effectors of a lytic type of pro-inflammatory cell death known as pyroptosis, they do also take part in other cell death processes (NETosis, secondary necrosis, or apoptosis) and exhibit cell-death independent functions depending on the cellular context. Among GSDMs, Gasdermin B (GSDMB) pyroptotic capacity has been a subject of conflicting findings in scientific literature even when its processing, and subsequent activation, by Granzyme A (GZMA) was decoded. Nevertheless, recent groundbreaking publications have shed light on the crucial role of alternative splicing in determining the pyroptotic capacity of GSDMB isoforms, which depends on the presence of exon 6-derived elements. This comprehensive review pays attention to the relevant structural differences among recently crystalized GSDMB isoforms. As a novelty, the structural aspects governing GSDMB isoform susceptibility to GZMA-mediated activation have been investigated. By elucidating the complex roles of GSDMB isoforms, this review aims to deepen the understanding of this multifunctional player and its potential implications in disease pathogenesis and therapeutic interventions. [Figure: see text].