Intravascular delivery of an MK2 inhibitory peptide to prevent restenosis after angioplasty.

Peripheral artery disease is commonly treated with balloon angioplasty, a procedure involving minimally invasive, transluminal insertion of a catheter to the site of stenosis, where a balloon is inflated to open the blockage, restoring blood flow. However, peripheral angioplasty has a high rate of restenosis, limiting long-term patency. Therefore, angioplasty is sometimes paired with delivery of cytotoxic drugs like paclitaxel to reduce neointimal tissue formation. We pursue intravascular drug delivery strategies that target the underlying cause of restenosis - intimal hyperplasia resulting from stress-induced vascular smooth muscle cell switching from the healthy contractile into a pathological synthetic phenotype. We have established MAPKAP kinase 2 (MK2) as a driver of this phenotype switch and seek to establish convective and contact transfer (coated balloon) methods for MK2 inhibitory peptide delivery to sites of angioplasty. Using a flow loop bioreactor, we showed MK2 inhibition in ex vivo arteries suppresses smooth muscle cell phenotype switching while preserving vessel contractility. A rat carotid artery balloon injury model demonstrated inhibition of intimal hyperplasia following MK2i coated balloon treatment in vivo. These studies establish both convective and drug coated balloon strategies as promising approaches for intravascular delivery of MK2 inhibitory formulations to improve efficacy of balloon angioplasty.

GSDMD KNOCKOUT ALLEVIATES SEPSIS-ASSOCIATED SKELETAL MUSCLE ATROPHY BY INHIBITING IL18/AMPK SIGNALING.

ABSTRACT: Background: Sepsis commonly leads to skeletal muscle atrophy, characterized by substantial muscle weakness and degeneration, ultimately contributing to an adverse prognosis. Studies have shown that programmed cell death is an important factor in the progression of muscle loss in sepsis. However, the precise role and mechanism of pyroptosis in skeletal muscle atrophy are not yet fully comprehended. Therefore, we aimed to examine the role and mechanism of action of the pyroptosis effector protein GSDMD in recognized cellular and mouse models of sepsis. Methods: The levels of GSDMD and N-GSDMD in skeletal muscle were evaluated 2, 4, and 8 days after cecal ligation and puncture. Sepsis was produced in mice that lacked the Gsdmd gene (Gsdmd knockout) and in mice with the normal Gsdmd gene (wild-type) using a procedure called cecal ligation and puncture. The degree of muscular atrophy in the gastrocnemius and tibialis anterior muscles was assessed 72 h after surgery in the septic mouse model. In addition, the architecture of skeletal muscles, protein expression, and markers associated with pathways leading to muscle atrophy were examined in mice from various groups 72 h after surgery. The in vitro investigations entailed the use of siRNA to suppress Gsdmd expression in C2C12 cells, followed by stimulation of these cells with lipopolysaccharide to evaluate the impact of Gsdmd downregulation on muscle atrophy and the related signaling cascades. Results: This study has demonstrated that the GSDMD protein, known as the "executive" protein of pyroptosis, plays a crucial role in the advancement of skeletal muscle atrophy in septic mice. The expression of N-GSDMD in the skeletal muscle of septic mice was markedly higher compared with the control group. The Gsdmd knockout mice exhibited notable enhancements in survival, muscle strength, and body weight compared with the septic mice. Deletion of the Gsdmd gene reduced muscular wasting in the gastrocnemius and tibialis anterior muscles caused by sepsis. Studies conducted in living organisms ( in vivo ) and in laboratory conditions ( in vitro ) have shown that the absence of the Gsdmd gene decreases indicators of muscle loss associated with sepsis by blocking the IL18/AMPK signaling pathway. Conclusion: The results of this study demonstrate that the lack of Gsdmd has a beneficial effect on septic skeletal muscle atrophy by reducing the activation of IL18/AMPK and inhibiting the ubiquitin-proteasome system and autophagy pathways. Therefore, our research provides vital insights into the role of pyroptosis in sepsis-related skeletal muscle wasting, which could potentially lead to the development of therapeutic and interventional approaches for preventing septic skeletal muscle atrophy.

RACK1 and NEK7 mediate GSDMD-dependent macrophage pyroptosis upon Streptococcus suis infection.

Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen that induces an NLRP3-dependent cytokine storm. NLRP3 inflammasome activation triggers not only an inflammatory response but also pyroptosis. However, the exact mechanism underlying S. suis-induced macrophage pyroptosis is not clear. Our results showed that SS2 induced the expression of pyroptosis-associated factors, including lactate dehydrogenase (LDH) release, propidium iodide (PI) uptake and GSDMD-N expression, as well as NLRP3 inflammasome activation and IL-1ß secretion. However, GSDMD deficiency and NLRP3 inhibition using MCC950 attenuated the SS2-induced expression of pyroptosis-associated factors, suggesting that SS2 induces NLRP3-GSDMD-dependent pyroptosis. Furthermore, RACK1 knockdown also reduced the expression of pyroptosis-associated factors. In addition, RACK1 knockdown downregulated the expression of NLRP3 and Pro-IL-1ß as well as the phosphorylation of P65. Surprisingly, the interaction between RACK1 and P65 was detected by co-immunoprecipitation, indicating that RACK1 induces macrophage pyroptosis by mediating the phosphorylation of P65 to promote the transcription of NLRP3 and pro-IL-1ß. Similarly, NEK7 knockdown decreased the expression of pyroptosis-associated factors and ASC oligomerization. Moreover, the results of co-immunoprecipitation revealed the interaction of NEK7-RACK1-NLRP3 during SS2 infection, demonstrating that NEK7 mediates SS2-induced pyroptosis via the regulation of NLRP3 inflammasome assembly and activation. These results demonstrate the important role of RACK1 and NEK7 in SS2-induced pyroptosis. Our study provides new insight into SS2-induced cell death.

Avermectin B1 mediates antitumor activity and induces autophagy in osteosarcoma through the AMPK/ULK1 signaling pathway.

BACKGROUND: Osteosarcoma is the most common malignant bone tumor in children and adolescents. Conventional chemotherapy remains unsatisfactory due to drug toxicity and resistance issues. Therefore, there is an urgent need to develop more effective treatments for advanced osteosarcoma. In the current study, we focused on evaluating the anticancer efficacy of avermectin B1, a novel avermectin analog, against osteosarcoma cells. METHODS: The half-inhibitory concentration of avermectin B1 was calculated in three osteosarcoma cell lines. Then, functional experiments were conducted to evaluate the effects of avermectin B1 on cell proliferation, the cell cycle, apoptosis and autophagy. Moreover, the AMPK/ULK1 signaling pathway was detected by Western blot assay. Finally, the in vivo effect of avermectin B1 on tumor growth and metastasis was investigated using the xenograft mouse model. To examine the role of the AMPK/ULK1 pathway, an AMPK-specific inhibitor (dorsomorphin) was used in combination with avermectin B1. RESULTS: Avermectin B1 inhibited the proliferation of osteosarcoma cells in a dose-dependent manner based on CCK8 and colony formation assays. Then, it was found to inhibit migration and invasion by wound healing assay and cell migration and invasion assay. In addition, avermectin B1 induced osteosarcoma cell apoptosis and autophagy. In vivo, avermectin B1 effectively inhibited osteosarcoma cell growth and pulmonary metastasis. Mechanistically, avermectin B1 activated the AMPK/ULK1 pathway to exert antitumor activity in vitro and in vivo. Dorsomorphin significantly attenuated the Avermectin B1-induced antitumor activities. CONCLUSION: Our study suggests that avermectin B1 is a potential agent to treat osteosarcoma cells through the AMPK/ULK1 signaling pathway.

NLRC5 exerts anti-endometriosis effects through inhibiting ERß-mediated inflammatory response.

BACKGROUND: Endometriosis is well known as a chronic inflammatory disease. The development of endometriosis is heavily influenced by the estrogen receptor ß (ERß), while NOD-like receptors (NLRs) family CARD domain-containing 5 (NLRC5) exhibits anti-inflammatory properties during endometriosis. However, whether NLRC5-mediated anti-inflammation is involved in the ERß-mediated endometriosis is still uncertain. This study aimed to assess that relation. METHODS: Nine cases of eutopic endometrial tissue and ten cases of ectopic endometrial tissue were collected from patients with endometriosis, and endometrial samples from ten healthy fertile women were analyzed, and the expression levels of ERß were quantified using immunohistochemistry (IHC). Subsequently, we constructed mouse model of endometriosis by intraperitoneal injection. We detected the expression of ERß, NLRC5, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-10 and measured the volume of ectopic lesions in mice with endometriosis. In vitro, human endometrial stromal cells (hESCs) were transfected respectively with ERß-overexpressing and NLRC5-overexpressing plasmids. We then assessed the expression of ERß and NLRC5 using quantitative real-time PCR (qRT-PCR) and western blot analysis. Furthermore, we measured the concentrations of TNF-α, IL-6, and IL-10 in the cell culture supernatant through enzyme-linked immunosorbent assay (ELISA). Additionally, we evaluated the migration and invasion ability of hESCs using transwell and wound healing assays. RESULTS: Inhibition of NLRC5 expression promotes the development of ectopic lesions in mice with endometriosis, upregulates the expression of pro-inflammatory factors TNF-α and IL-6, and downregulates the expression of anti-inflammatory factor IL-10. The high expression of NLRC5 in endometriosis depended on the ERß overexpression. And ERß promoted the migration of hESCs partially depend on inflammatory microenvironment. Lastly, NLRC5 overexpression inhibited ERß-mediated development and inflammatory response of endometriosis. CONCLUSIONS: Our results suggest that the innate immune molecule NLRC5-mediated anti-inflammation participates in ERß-mediated endometriosis development, and partly clarifies the pathological mechanism of endometriosis, expanding our knowledge of the specific molecules related to the inflammatory response involved in endometriosis and potentially providing a new therapeutic target for endometriosis.

RMRP accelerates ligamentum flavum hypertrophy by regulating GSDMD-mediated pyroptosis through Gli1 SUMOylation.

Hypertrophy of ligamentum flavum (LF) is a significant contributing factor to lumbar spinal canal stenosis (LSCS). lncRNA plays a vital role in organ fibrosis, but its role in LF fibrosis remains unclear. Our previous findings have demonstrated that Hedgehog-Gli1 signaling is a critical driver leading to LF hypertrophy. Through the RIP experiment, our group found lnc-RMRP was physically associated with Gli1 and exhibited enrichment in Gli1-activated LF cells. Histological studies revealed elevated expression of RMRP in hypertrophic LF. In vitro experiments further confirmed that RMRP promoted Gli1 SUMO modification and nucleus transfer. Mechanistically, RMRP induced GSDMD-mediated pyroptosis, proinflammatory activation, and collagen expression through the Hedgehog pathway. Notably, the mechanical stress-induced hypertrophy of LF in rabbit exhibited analogous pathological changes of LF fibrosis occurred in human and showed enhanced levels of collagen and α-SMA. Knockdown of RMRP resulted in the decreased expression of fibrosis and pyroptosis-related proteins, ultimately ameliorating fibrosis. The above data concluded that RMRP exerts a crucial role in regulating GSDMD-mediated pyroptosis of LF cells via Gli1 SUMOylation, thus indicating that targeting RMRP could serve as a potential and effective therapeutic strategy for LF hypertrophy and fibrosis.

Paeoniflorin inhibited GSDMD to alleviate ANIT-induced cholestasis via pyroptosis signaling pathway.

BACKGROUND: Cholestasis (CT) is a group of disorders caused by impaired production, secretion or excretion of bile. This may result in the deposition of bile components in the blood and liver, which in turn causes damage to liver cells and other tissues. If untreated, CT can progress to severe complications, including cirrhosis, liver failure, and potentially life-threatening conditions. OBJECTIVE: This research was intended to elucidate the function and mechanism of Paeoniflorin (PF) in ameliorating ANIT-induced pyroptosis in CT. METHODS: CT models were established in SD rats and HepG2 cells through ANIT treatment. Histological examination was conducted using haematoxylin and eosin (HE) staining to assess the histopathological alterations in the liver. Network pharmacology was employed to identify potential PF targets in CT treatment. To evaluate pyroptosis levels, various methods were used, including serum biochemical analysis, Enzyme-Linked Immunosorbent Assay (ELISA), immunofluorescence (IF), immunohistochemistry (IHC), Western blotting, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The HuProt™ 20K Chip was utilized to pinpoint potential PF-binding targets. PF's direct mechanisms in CT treatment were explored using molecular docking (MD), molecular dynamics simulations (MDS), Cellular Thermal Shift Assay (CETSA), and Surface Plasmon Resonance (SPR). RESULTS: PF administration was found to alleviate ANIT-induced liver pathology, enhance liver function markers, and improve cell viability. Network pharmacology and pyroptosis inhibitor studies suggested that PF might mitigate CT via the NLRP3-dependent pyroptosis pathway. This hypothesis was further supported by Western blotting, IF, and IHC analyses, which indicated PF's potential to inhibit NLRP3-dependent pyroptosis in CT. GSDMD was identified as a target through HuProt™ 20K Chip screening. The binding affinity of PF to GSDMD was validated through MD, MDS, CETSA, and SPR techniques. Additionally, the regulatory impact of GSDMD on downstream inflammatory pathways was confirmed by ELISA and IHC. CONCLUSION: PF exhibited a hepatoprotective effect in ANIT-induced CT, primarily by targeting GSDMD, thereby suppressing ANIT-induced pyroptosis and the subsequent release of inflammatory mediators.

Gasdermin D and Gasdermin E Are Dispensable for Silica-Mediated IL-1ß Secretion from Mouse Macrophages.

Silica crystals activate the NLRP3 inflammasome in macrophages, resulting in the caspase-1-dependent secretion of the proinflammatory cytokine IL-1ß. Caspase-1-mediated cleavage of gasdermin D (GSDMD) triggers the formation of GSDMD pores, which drive pyroptotic cell death and facilitate the rapid release of IL-1ß. However, the role of GSDMD in silica-induced lung injury is unclear. In this study, we show that although silica-induced lung injury is dependent on the inflammasome adaptor ASC and IL-1R1 signaling, GSDMD is dispensable for acute lung injury. Although the early rapid secretion of IL-1ß in response to ATP and nigericin was GSDMD dependent, GSDMD was not required for IL-1ß release at later time points. Similarly, secretion of IL-1ß from macrophages in response to silica and alum proceeded in a GSDMD-independent manner. We further found that gasdermin E did not contribute to macrophage IL-1ß secretion in the absence of GSDMD in vitro and was also not necessary for silica-induced acute lung injury in vivo. These findings demonstrate that GSDMD and gasdermin E are dispensable for IL-1ß secretion in response to silica in vitro and in silica-induced acute lung injury in vivo.

In silico comparative analysis of cestode and human NPC1 provides insights for ezetimibe repurposing to visceral cestodiases treatment.

Visceral cestodiases, like cysticercoses and echinococcoses, are caused by cystic larvae from parasites of the Cestoda class and are endemic or hyperendemic in many areas of the world. Current therapeutic approaches for these diseases are complex and present limitations and risks. Therefore, new safer and more effective treatments are urgently needed. The Niemann-Pick C1 (NPC1) protein is a cholesterol transporter that, based on genomic data, would be the solely responsible for cholesterol uptake in cestodes. Considering that human NPC1L1 is a known target of ezetimibe, used in the treatment of hypercholesterolemia, it has the potential for repurposing for the treatment of visceral cestodiases. Here, phylogenetic, selective pressure and structural in silico analyses were carried out to assess NPC1 evolutive and structural conservation, especially between cestode and human orthologs. Two NPC1 orthologs were identified in cestode species (NPC1A and NPC1B), which likely underwent functional divergence, leading to the loss of cholesterol transport capacity in NPC1A. Comparative interaction analyses performed by molecular docking of ezetimibe with human NPC1L1 and cestode NPC1B pointed out to similarities that consolidate the idea of cestode NPC1B as a target for the repurposing of ezetimibe as a drug for the treatment of visceral cestodiases.

The Role of circHIPK3 in Tumorigenesis and Its Potential as a Biomarker in Lung Cancer.

Lung cancer treatment and detection can be improved by the identification of new biomarkers. Novel approaches in investigating circular RNAs (circRNAs) as biomarkers have yielded promising results. A circRNA molecule circHIPK3 was found to be widely expressed in non-small-cell lung cancer (NSCLC) cells, where it plays a crucial role in lung cancer tumorigenesis. CircHIPK3 promotes lung cancer progression by sponging oncosuppressive miRNAs such as miR-124, miR-381-3p, miR-149, and miR-107, which results in increased cell proliferation, migration, and resistance to therapies. Inhibiting circHIPK3 has been demonstrated to suppress tumour growth and induce apoptosis, which suggests its potential use in the development of new lung cancer treatment strategies targeting circHIPK3-related pathways. As a biomarker, circHIPK3 shows promise for early detection and monitoring of lung cancer. CircHIPK3 increased expression levels in lung cancer cells, and its potential link to metastasis risk highlights its clinical relevance. Given the promising preliminary findings, more clinical trials are needed to validate circHIPK3 efficacy as a biomarker. Moreover, future research should determine if the mechanisms discovered in NSCLC apply to small cell lung cancer (SCLC) to investigate circHIPK3-targeted therapies for SCLC.

Antagonistic nanobodies implicate mechanism of GSDMD pore formation and potential therapeutic application.

Inflammasome activation results in the cleavage of gasdermin D (GSDMD) by pro-inflammatory caspases. The N-terminal domains (GSDMDNT) oligomerize and assemble pores penetrating the target membrane. As methods to study pore formation in living cells are insufficient, the order of conformational changes, oligomerization, and membrane insertion remained unclear. We have raised nanobodies (VHHs) against human GSDMD and find that cytosolic expression of VHHGSDMD-1 and VHHGSDMD-2 prevents oligomerization of GSDMDNT and pyroptosis. The nanobody-stabilized GSDMDNT monomers partition into the plasma membrane, suggesting that membrane insertion precedes oligomerization. Inhibition of GSDMD pore formation switches cell death from pyroptosis to apoptosis, likely driven by the enhanced caspase-1 activity required to activate caspase-3. Recombinant antagonistic nanobodies added to the extracellular space prevent pyroptosis and exhibit unexpected therapeutic potential. They may thus be suitable to treat the ever-growing list of diseases caused by activation of (non-) canonical inflammasomes.

NLRP1-dependent activation of Gasdermin D in neutrophils controls cutaneous leishmaniasis.

Intracellular pathogens that replicate in host myeloid cells have devised ways to inhibit the cell's killing machinery. Pyroptosis is one of the host strategies used to reduce the pathogen replicating niche and thereby control its expansion. The intracellular Leishmania parasites can survive and use neutrophils as a silent entry niche, favoring subsequent parasite dissemination into the host. Here, we show that Leishmania mexicana induces NLRP1- and caspase-1-dependent Gasdermin D (GSDMD)-mediated pyroptosis in neutrophils, a process critical to control the parasite-induced pathology. In the absence of GSDMD, we observe an increased number of infected dermal neutrophils two days post-infection. Using adoptive neutrophil transfer in neutropenic mice, we show that pyroptosis contributes to the regulation of the neutrophil niche early after infection. The critical role of neutrophil pyroptosis and its positive influence on the regulation of the disease outcome was further demonstrated following infection of mice with neutrophil-specific deletion of GSDMD. Thus, our study establishes neutrophil pyroptosis as a critical regulator of leishmaniasis pathology.

Starvation-induced phosphorylation activates gasdermin A to initiate pyroptosis.

Pyroptosis, a pro-inflammatory form of programmed cell death, is crucial for host defense against pathogens and danger signals. Proteolytic cleavage of gasdermin proteins B-E (GSDMB-GSDME) is well established as a trigger for pyroptosis, but the intracellular activation mechanism of GSDMA remains elusive. Here, we demonstrate that severe starvation induces pyroptosis through phosphorylation-induced activation of GSDMA. Nutrient stresses stimulate GSDMA activation via phosphorylation mediated by Unc-51-like autophagy-activating kinase 1 (ULK1). Phosphorylation of Ser353 on human GSDMA by ULK1 or the phospho-mimetic Ser353Asp mutant of GSDMA liberates GSDMA from auto-inhibition, facilitating its membrane targeting and initiation of pyroptosis. To further validate the significance of GSDMA phosphorylation, we generated a constitutively active mutant Ser354Asp of mouse Gsdma, which induced skin inflammation and hyperplasia in mice, reminiscent of phenotypes with activated Gsdma. This study uncovers phosphorylation of GSDMA as a mechanism underlying pyroptosis initiation and cellular response to nutrient stress.

Pericentriolar material 1 promotes intestinal inflammation in ulcerative colitis by activating NLRP3/gasdermin D-mediated macrophage pyroptosis.

Excessive proinflammatory cytokine release induced by pyroptosis plays a vital role in intestinal mucosal inflammation in ulcerative colitis (UC). Several pyroptosis-related factors are regulated by the centrosome. Pericentriolar material 1 (PCM1) is a primary component of centriolar satellites that is present as cytoplasmic granules around the centrosome. Our previous study revealed that PCM1 was highly expressed in UC patients, but the role of PCM1 in UC remains unknown. This study aimed to elucidate the role of PCM1 in the development of UC, especially the mechanism in pyroptosis process of UC. Clinical mucosal sample and dextran sulfate sodium (DSS)-induced colitis mouse were used to reveal the association between PCM1 and intestinal inflammation. Intestinal epithelial cell-specific PCM1-knockout mice were constructed to determine the role of PCM1 in colitis. Finally, PCM1 RNA interference and overexpression assays in THP1 cells were employed to study the molecular mechanisms of PCM1 in inflammatory responses and pyroptosis. We found that PCM1 expression was upregulated in the colonic mucosa of UC patients and positively correlated with inflammatory indicators. PCM1 expression was elevated in DSS-induced colitis mice and was reduced after methylprednisolone treatment. In the DSS colitis model, intestinal-specific PCM1-knockout mice exhibited milder intestinal inflammation and lower pyroptosis levels than wild-type mice. In cell level, PCM1 exerted a proinflammatory effect by activating the NLRP3 inflammasome and triggering subsequent gasdermin D-mediated pyroptosis to release IL-1ß and IL-18. In conclusion, PCM1 mediates activation of the NLRP3 inflammasome and gasdermin D-dependent pyroptosis, ultimately accelerating intestinal inflammation in UC. These findings revealed a previously unknown role of PCM1 in initiating intestinal mucosal inflammation and pyroptosis in UC, and this factor is expected to be a regulator in the complex inflammatory network of UC.

LncRNA SLNCR1 facilitates angiogenesis and tumor growth in melanoma via DNMT1-mediated epigenetically silencing SPRY2.

BACKGROUND: The malignancy of melanoma is attributed to its pronounced invasiveness, extensive vascularization, and rapid tumor cell growth and metastasis. LncRNA SLNCR1 is closely associated with a variety of aggressive tumors. However, our understanding of SLNCR1 influences on malignant melanoma growth metastasis mechanism especially proangiogenic mechanism remains unclear. METHODS: The expression of SLNCR1 was evaluated in melanoma tissues, adjacent tissues, melanoma cell lines. The abilities of SLNCR1 on proliferation, migration, and angiogenesis of HUVECs were detected by CCK-8, flow cytometry, and Western blot assays. The association between SLNCR1, DNMT1, and SPRY2 was assessed by ChIP, RIP, and Western blot assays. The effect of SLNCR1 on tumor growth was determined using a xenograft model in nude mice. RESULTS: SLNCR1 was confirmed to be highly expressed in melanoma tissues and cells. CM from melanoma cells transfected with sh-SLNCR1 attenuated proliferation, migration, and angiogenesis of HUVECs. Moreover, loss of SLNCR1 hindered tumor growth and metastasis, as evidenced by reduced tumor size and weight, as well as angiogenesis. Mechanistic studies revealed that SLNCR1 silenced SPRY2 expression, likely through enhancing DNMT1-mediated DNA methylation of SPRY2 promoter. CONCLUSION: SLNCR1 is an oncogene that interacts with DNMT1 to mediate SPRY2 methylation, thereby suppressing SPRY2 expression and promoting the angiogenesis and tumor growth in melanoma. SLNCR1 may serve as a potential target for melanoma treatment.

GSDMD is associated with survival in human breast cancer but does not impact anti-tumor immunity in a mouse breast cancer model.

Inflammation plays a pivotal role in cancer development, with chronic inflammation promoting tumor progression and treatment resistance, whereas acute inflammatory responses contribute to protective anti-tumor immunity. Gasdermin D (GSDMD) mediates the release of pro-inflammatory cytokines such as IL-1ß. While the release of IL-1ß is directly linked to the progression of several types of cancers, the role of GSDMD in cancer is less clear. In this study, we show that GSDMD expression is upregulated in human breast, kidney, liver, and prostate cancer. Higher GSDMD expression correlated with increased survival in primary breast invasive carcinoma (BRCA), but not in liver hepatocellular carcinoma (LIHC). In BRCA, but not in LIHC, high GSDMD expression correlated with a myeloid cell signature associated with improved prognosis. To further investigate the role of GSDMD in anticancer immunity, we induced breast cancer and hepatoma tumors in GSDMD-deficient mice. Contrary to our expectations, GSDMD deficiency had no effect on tumor growth, immune cell infiltration, or cytokine expression in the tumor microenvironment, except for Cxcl10 upregulation in hepatoma tumors. In vitro and in vivo innate immune activation with TLR ligands, that prime inflammatory responses, revealed no significant difference between GSDMD-deficient and wild-type mice. These results suggest that the impact of GSDMD on anticancer immunity is dependent on the tumor type. They underscore the complex role of inflammatory pathways in cancer, emphasizing the need for further exploration into the multifaceted effects of GSDMD in various tumor microenvironments. As several pharmacological modulators of GSDMD are available, this may lead to novel strategies for combination therapy in cancer.

Role of gasdermin D in inflammatory diseases: from mechanism to therapeutics.

Inflammatory diseases compromise a clinically common and diverse group of conditions, causing detrimental effects on body functions. Gasdermins (GSDM) are pore-forming proteins, playing pivotal roles in modulating inflammation. Belonging to the GSDM family, gasdermin D (GSDMD) actively mediates the pathogenesis of inflammatory diseases by mechanistically regulating different forms of cell death, particularly pyroptosis, and cytokine release, in an inflammasome-dependent manner. Aberrant activation of GSDMD in different types of cells, such as immune cells, cardiovascular cells, pancreatic cells and hepatocytes, critically contributes to the persistent inflammation in different tissues and organs. The contributory role of GSDMD has been implicated in diabetes mellitus, liver diseases, cardiovascular diseases, neurodegenerative diseases, and inflammatory bowel disease (IBD). Clinically, alterations in GSDMD levels are potentially indicative to the occurrence and severity of diseases. GSDMD inhibition might represent an attractive therapeutic direction to counteract the progression of inflammatory diseases, whereas a number of GSDMD inhibitors have been shown to restrain GSDMD-mediated pyroptosis through different mechanisms. This review discusses the current understanding and future perspectives on the role of GSDMD in the development of inflammatory diseases, as well as the clinical insights of GSDMD alterations, and therapeutic potential of GSDMD inhibitors against inflammatory diseases. Further investigation on the comprehensive role of GSDM shall deepen our understanding towards inflammation, opening up more diagnostic and therapeutic opportunities against inflammatory diseases.

TRIM44, a Novel Prognostic Marker, Supports the Survival of Proteasome-Resistant Multiple Myeloma Cells.

TRIM44, a tripartite motif (TRIM) family member, is pivotal in linking the ubiquitin-proteasome system (UPS) to autophagy in multiple myeloma (MM). However, its prognostic impact and therapeutic potential remain underexplored. Here, we report that TRIM44 overexpression is associated with poor prognosis in a Multiple Myeloma Research Foundation (MMRF) cohort of 858 patients, persisting across primary and recurrent MM cases. TRIM44 expression notably increases in advanced MM stages, indicating its potential role in disease progression. Single-cell RNA sequencing across MM stages showed significant TRIM44 upregulation in smoldering MM (SMM) and MM compared to normal bone marrow, especially in patients with t(4;14) cytogenetic abnormalities. This analysis further identified high TRIM44 expression as predictive of lower responsiveness to proteasome inhibitor (PI) treatments, underscoring its critical function in the unfolded protein response (UPR) in TRIM44-high MM cells. Our findings also demonstrate that TRIM44 facilitates SQSTM1 oligomerization under oxidative stress, essential for its phosphorylation and subsequent autophagic degradation. This process supports the survival of PI-resistant MM cells by activating the NRF2 pathway, which is crucial for oxidative stress response and, potentially, other chemotherapy-induced stressors. Additionally, TRIM44 counters the TRIM21-mediated suppression of the antioxidant response, enhancing MM cell survival under oxidative stress. Collectively, our discoveries highlight TRIM44's significant role in MM progression and resistance to therapy, suggesting its potential value as a therapeutic target.

SMAC mimetic drives microglia phenotype and glioblastoma immune microenvironment.

Tumor-associated macrophages/microglia (TAMs) are highly plastic and heterogeneous immune cells that can be immune-supportive or tumor-supportive depending of the microenvironment. TAMs are the most abundant immune cells in glioblastoma (GB), and play a key role in immunosuppression. Therefore, TAMs reprogramming toward immune-supportive cells is a promising strategy to overcome immunosuppression. By leveraging scRNAseq human GB databases, we identified that Inhibitor of Apoptosis Proteins (IAP) were expressed by TAMs. To investigate their role in TAMs-related immunosuppression, we antagonized IAP using the central nervous system permeant SMAC mimetic GDC-0152 (SMg). On explants and cultured immune cells isolated from human GB samples, SMg modified TAMs activity. We showed that SMg treatment promoted microglia pro-apoptotic and anti-tumoral function via caspase-3 pro-inflammatory cleavage and the inhibition of tumoroids growth. Then we designed a relevant immunogenic mouse GB model to decipher the spatio-temporal densities, distribution, phenotypes and function of TAMs with or without SMg treatment. We used 3D imaging techniques, a transgenic mouse with fluorescent TAM subsets and mass cytometry. We confirmed that SMg promoted microglia activation, antigen-presenting function and tumor infiltration. In addition, we observed a remodeling of blood vessels, a decrease in anti-inflammatory macrophages and an increased level of monocytes and their mo-DC progeny. This remodeling of the TAM landscape is associated with an increase in CD8 T cell density and activation. Altogether, these results demonstrated that SMg drives the immunosuppressive basal microglia toward an active phenotype with pro-apoptotic and anti-tumoral function and modifies the GB immune landscape. This identifies IAP as targets of choice for a potential mechanism-based therapeutic strategy and SMg as a promising molecule for this application.