InVivoMAb anti-mouse CD172a (SIRPα)

Nuclear receptors regulate key functions of mononuclear phagocytes and are critical components of the innate immune system, acting as regulators of organ health and disease. In healthy mice, the loss of the nuclear orphan receptor NR2F6 alters tissue-resident macrophage populations in the liver, lung, and spleen. In response to Salmonella Typhimurium infection, Nr2f6-deficient mice exhibit improved clinical outcomes, characterized by reduced weight loss, bacterial loads in the spleen and liver, and decreased plasma pro-inflammatory cytokines. Despite unchanged basal iron metabolism in the spleen and liver, iron regulatory proteins and the interleukin (IL)-6-hepcidin axis are altered in Nr2f6-deficient mice during Salmonella infection, reducing hypoferremia. Transcriptomic analysis of splenic red pulp macrophages reveals significant alterations of phagocytosis-related genes, including upregulation of signal-regulatory protein alpha (Sirpa). In vitro, phagocytosis of red blood cells, regulated by the inhibitory CD47-Sirpα axis, and Salmonella Typhimurium phagocytosis are significantly impaired in Nr2f6-deficient splenic macrophages. Blocking Sirpα in vitro restores the phagocytic activity of Nr2f6-deficient macrophages to wild-type levels. In vivo, Salmonella Typhimurium loads are partially increased post-infection in anti-Sirpα treated Nr2f6-deficient mice. These findings uncover a previously unrecognized role of NR2F6 in host-pathogen interactions, positioning it as a potential therapeutic target for infectious diseases.

Tumor-infiltrating myeloid cells (TIMs) are pivotal cell populations involved in the immunosuppressive tumor immune microenvironment (TIME). However, there has been little success in large-scale clinical trials of myeloid cell modulators. We aim to investigate potential molecular targets for TIMs and disclose the underlying mechanism. Using mass cytometry by time of flight (CyTOF), we analyzed 24 spontaneous HCC tissues from mouse. Orthotopic and subcutaneous tumor models were established with or without anti-SIRPα antibody treatment. Patient-derived tumor xenografts model (PDX) was used to identify the CD47-SIRPα axis blocked therapy. In 24 murine spontaneous HCC tissues, we observed that the proportion of myeloid-derived suppressor cells (MDSCs) plus macrophages accounts for 40-90% of TIMs and SIRPα was highly expressed in TIMs, especially in macrophages and MDSCs. Through in vivo experiments, we showed that anti-SIRPα therapy inhibited tumor growth, accompanied by increased CD8+ T cells infiltration and decreased TIMs including MDSCs and macrophages. We found that anti-SIRPα inhibited immunosuppressive function, migration and PD-L1 expression of myeloid cells. In a series of in vivo experiments, we demonstrated the anti-tumor and immune-active effect of SIRPα-blocked therapy. Mechanistically, anti-SIRPα inhibited the immunosuppressive function and PD-L1 expression of TIMs through downregulating PI3K/AKT signaling in myeloid cells. At last, anti-SIRPα enhanced the antitumor effect of anti-PD-L1 therapy in orthotopic and spontaneous murine models. Together, SIRPα blocked therapy reversed the immunosuppressive TIME, which provides a promising therapeutic rationale for increasing the efficacy of anti-PD-L1 therapy in treating HCC.

Tumor-infiltrating myeloid cells (TIMs) are pivotal cell populations involved in the immunosuppressive tumor immune microenvironment (TIME). However, there has been little success in large-scale clinical trials of myeloid cell modulators. We aim to investigate potential molecular targets for TIMs and disclose the underlying mechanism. Using mass cytometry by time of flight (CyTOF), we analyzed 24 spontaneous HCC tissues from mouse. Orthotopic and subcutaneous tumor models were established with or without anti-SIRPα antibody treatment. Patient-derived tumor xenografts model (PDX) was used to identify the CD47-SIRPα axis blocked therapy. In 24 murine spontaneous HCC tissues, we observed that the proportion of myeloid-derived suppressor cells (MDSCs) plus macrophages accounts for 40-90% of TIMs and SIRPα was highly expressed in TIMs, especially in macrophages and MDSCs. Through in vivo experiments, we showed that anti-SIRPα therapy inhibited tumor growth, accompanied by increased CD8+ T cells infiltration and decreased TIMs including MDSCs and macrophages. We found that anti-SIRPα inhibited immunosuppressive function, migration and PD-L1 expression of myeloid cells. In a series of in vivo experiments, we demonstrated the anti-tumor and immune-active effect of SIRPα-blocked therapy. Mechanistically, anti-SIRPα inhibited the immunosuppressive function and PD-L1 expression of TIMs through downregulating PI3K/AKT signaling in myeloid cells. At last, anti-SIRPα enhanced the antitumor effect of anti-PD-L1 therapy in orthotopic and spontaneous murine models. Together, SIRPα blocked therapy reversed the immunosuppressive TIME, which provides a promising therapeutic rationale for increasing the efficacy of anti-PD-L1 therapy in treating HCC.

Tumor-infiltrating myeloid cells (TIMs) are pivotal cell populations involved in the immunosuppressive tumor immune microenvironment (TIME). However, there has been little success in large-scale clinical trials of myeloid cell modulators. We aim to investigate potential molecular targets for TIMs and disclose the underlying mechanism. Using mass cytometry by time of flight (CyTOF), we analyzed 24 spontaneous HCC tissues from mouse. Orthotopic and subcutaneous tumor models were established with or without anti-SIRPα antibody treatment. Patient-derived tumor xenografts model (PDX) was used to identify the CD47-SIRPα axis blocked therapy. In 24 murine spontaneous HCC tissues, we observed that the proportion of myeloid-derived suppressor cells (MDSCs) plus macrophages accounts for 40-90% of TIMs and SIRPα was highly expressed in TIMs, especially in macrophages and MDSCs. Through in vivo experiments, we showed that anti-SIRPα therapy inhibited tumor growth, accompanied by increased CD8+ T cells infiltration and decreased TIMs including MDSCs and macrophages. We found that anti-SIRPα inhibited immunosuppressive function, migration and PD-L1 expression of myeloid cells. In a series of in vivo experiments, we demonstrated the anti-tumor and immune-active effect of SIRPα-blocked therapy. Mechanistically, anti-SIRPα inhibited the immunosuppressive function and PD-L1 expression of TIMs through downregulating PI3K/AKT signaling in myeloid cells. At last, anti-SIRPα enhanced the antitumor effect of anti-PD-L1 therapy in orthotopic and spontaneous murine models. Together, SIRPα blocked therapy reversed the immunosuppressive TIME, which provides a promising therapeutic rationale for increasing the efficacy of anti-PD-L1 therapy in treating HCC.

Tumor-infiltrating myeloid cells (TIMs) are pivotal cell populations involved in the immunosuppressive tumor immune microenvironment (TIME). However, there has been little success in large-scale clinical trials of myeloid cell modulators. We aim to investigate potential molecular targets for TIMs and disclose the underlying mechanism. Using mass cytometry by time of flight (CyTOF), we analyzed 24 spontaneous HCC tissues from mouse. Orthotopic and subcutaneous tumor models were established with or without anti-SIRPα antibody treatment. Patient-derived tumor xenografts model (PDX) was used to identify the CD47-SIRPα axis blocked therapy. In 24 murine spontaneous HCC tissues, we observed that the proportion of myeloid-derived suppressor cells (MDSCs) plus macrophages accounts for 40-90% of TIMs and SIRPα was highly expressed in TIMs, especially in macrophages and MDSCs. Through in vivo experiments, we showed that anti-SIRPα therapy inhibited tumor growth, accompanied by increased CD8+ T cells infiltration and decreased TIMs including MDSCs and macrophages. We found that anti-SIRPα inhibited immunosuppressive function, migration and PD-L1 expression of myeloid cells. In a series of in vivo experiments, we demonstrated the anti-tumor and immune-active effect of SIRPα-blocked therapy. Mechanistically, anti-SIRPα inhibited the immunosuppressive function and PD-L1 expression of TIMs through downregulating PI3K/AKT signaling in myeloid cells. At last, anti-SIRPα enhanced the antitumor effect of anti-PD-L1 therapy in orthotopic and spontaneous murine models. Together, SIRPα blocked therapy reversed the immunosuppressive TIME, which provides a promising therapeutic rationale for increasing the efficacy of anti-PD-L1 therapy in treating HCC.

Tumor-infiltrating myeloid cells (TIMs) are pivotal cell populations involved in the immunosuppressive tumor immune microenvironment (TIME). However, there has been little success in large-scale clinical trials of myeloid cell modulators. We aim to investigate potential molecular targets for TIMs and disclose the underlying mechanism. Using mass cytometry by time of flight (CyTOF), we analyzed 24 spontaneous HCC tissues from mouse. Orthotopic and subcutaneous tumor models were established with or without anti-SIRPα antibody treatment. Patient-derived tumor xenografts model (PDX) was used to identify the CD47-SIRPα axis blocked therapy. In 24 murine spontaneous HCC tissues, we observed that the proportion of myeloid-derived suppressor cells (MDSCs) plus macrophages accounts for 40-90% of TIMs and SIRPα was highly expressed in TIMs, especially in macrophages and MDSCs. Through in vivo experiments, we showed that anti-SIRPα therapy inhibited tumor growth, accompanied by increased CD8+ T cells infiltration and decreased TIMs including MDSCs and macrophages. We found that anti-SIRPα inhibited immunosuppressive function, migration and PD-L1 expression of myeloid cells. In a series of in vivo experiments, we demonstrated the anti-tumor and immune-active effect of SIRPα-blocked therapy. Mechanistically, anti-SIRPα inhibited the immunosuppressive function and PD-L1 expression of TIMs through downregulating PI3K/AKT signaling in myeloid cells. At last, anti-SIRPα enhanced the antitumor effect of anti-PD-L1 therapy in orthotopic and spontaneous murine models. Together, SIRPα blocked therapy reversed the immunosuppressive TIME, which provides a promising therapeutic rationale for increasing the efficacy of anti-PD-L1 therapy in treating HCC.

Tumor-infiltrating myeloid cells (TIMs) are pivotal cell populations involved in the immunosuppressive tumor immune microenvironment (TIME). However, there has been little success in large-scale clinical trials of myeloid cell modulators. We aim to investigate potential molecular targets for TIMs and disclose the underlying mechanism. Using mass cytometry by time of flight (CyTOF), we analyzed 24 spontaneous HCC tissues from mouse. Orthotopic and subcutaneous tumor models were established with or without anti-SIRPα antibody treatment. Patient-derived tumor xenografts model (PDX) was used to identify the CD47-SIRPα axis blocked therapy. In 24 murine spontaneous HCC tissues, we observed that the proportion of myeloid-derived suppressor cells (MDSCs) plus macrophages accounts for 40-90% of TIMs and SIRPα was highly expressed in TIMs, especially in macrophages and MDSCs. Through in vivo experiments, we showed that anti-SIRPα therapy inhibited tumor growth, accompanied by increased CD8+ T cells infiltration and decreased TIMs including MDSCs and macrophages. We found that anti-SIRPα inhibited immunosuppressive function, migration and PD-L1 expression of myeloid cells. In a series of in vivo experiments, we demonstrated the anti-tumor and immune-active effect of SIRPα-blocked therapy. Mechanistically, anti-SIRPα inhibited the immunosuppressive function and PD-L1 expression of TIMs through downregulating PI3K/AKT signaling in myeloid cells. At last, anti-SIRPα enhanced the antitumor effect of anti-PD-L1 therapy in orthotopic and spontaneous murine models. Together, SIRPα blocked therapy reversed the immunosuppressive TIME, which provides a promising therapeutic rationale for increasing the efficacy of anti-PD-L1 therapy in treating HCC.

Cancer cells can overexpress CD47, an innate immune checkpoint that prevents phagocytosis upon interaction with signal regulatory protein alpha (SIRPα) expressed in macrophages and other myeloid cells. Several clinical trials have reported that CD47 blockade reduces tumor growth in hematological malignancies. However, CD47 blockade has shown modest results in solid tumors, including melanoma. Our group has demonstrated that histone deacetylase 6 inhibitors (HDAC6is) have immunomodulatory properties, such as controlling macrophage phenotype and inflammatory properties. However, the molecular and cellular mechanisms controlling these processes are not fully understood. In this study, we evaluated the role of HDAC6 in regulating the CD47/SIRPα axis and phagocytosis in macrophages.

Mice with SHP1 proteins, which have a single amino acid substitution from tyrosine-208 residue to asparagine (hereafter Ptpn6spin mice), develop an autoinflammatory disease with inflamed footpads. Genetic crosses to study CD47 function in Ptpn6spin mice bred Ptpn6spin × Cd47-/- mice that were not born at the expected Mendelian ratio. Ptpn6spin bone marrow cells, when transferred into lethally irradiated Cd47-deficient mice, caused marked weight loss and subsequent death. At a cellular level, Ptpn6-deficient neutrophils promoted weight loss and death of the lethally irradiated Cd47-/- recipients. We posited that leakage of gut microbiota promotes morbidity and mortality in Cd47-/- mice receiving Ptpn6spin cells. Colonic cell death and gut leakage were substantially increased in the diseased Cd47-/- mice. Last, IL-1 blockade using anakinra rescued the morbidity and mortality observed in the diseased Cd47-/- mice. These data together demonstrate a protective role for CD47 in tempering pathogenic neutrophils in the Ptpn6spin mice.

Necroptosis contributes to hepatocyte death in nonalcoholic steatohepatitis (NASH), but the fate and roles of necroptotic hepatocytes (necHCs) in NASH remain unknown. We show here that the accumulation of necHCs in human and mouse NASH liver is associated with an up-regulation of the "don't-eat-me" ligand CD47 on necHCs, but not on apoptotic hepatocytes, and an increase in the CD47 receptor SIRPα on liver macrophages, consistent with impaired macrophage-mediated clearance of necHCs. In vitro, necHC clearance by primary liver macrophages was enhanced by treatment with either anti-CD47 or anti-SIRPα. In a proof-of-concept mouse model of inducible hepatocyte necroptosis, anti-CD47 antibody treatment increased necHC uptake by liver macrophages and inhibited markers of hepatic stellate cell (HSC) activation, which is responsible for liver fibrogenesis. Treatment of two mouse models of diet-induced NASH with anti-CD47, anti-SIRPα, or AAV8-H1-shCD47 to silence CD47 in hepatocytes increased the uptake of necHC by liver macrophages and decreased markers of HSC activation and liver fibrosis. Anti-SIRPα treatment avoided the adverse effect of anemia found in anti-CD47-treated mice. These findings provide evidence that impaired clearance of necHCs by liver macrophages due to CD47-SIRPα up-regulation contributes to fibrotic NASH, and suggest therapeutic blockade of the CD47-SIRPα axis as a strategy to decrease the accumulation of necHCs in NASH liver and dampen the progression of hepatic fibrosis.