Marc van Regenmortel, personal recollections on a forward-thinking editor.

Marc van Regenmortel was the Editor-in-Chief of the Journal of Molecular Recognition for the last 25 years. Without attempting to summarize Marc's exceptional career and achievements, we would like to tell the story of the tortuous and contingent path to the unravelling of a key molecular recognition process in antigenicity. Life is indeed full of contingencies and scientific life, full of meetings and random encounters, is prone to contingencies, a key element in discovery and innovation.

P21 facilitates macrophage chemotaxis by promoting CCL7 in the lung epithelial cell lines treated with radiation and bleomycin.

BACKGROUND: Interstitial lung diseases (ILDs) can be induced and even exacerbated by radiotherapy in thoracic cancer patients. The roles of immune responses underlying the development of these severe lung injuries are still obscure and need to be investigated. METHODS: A severe lung damage murine model was established by delivering 16 Gy X-rays to the chest of mice that had been pre-treated with bleomycin (BLM) and thus hold ILDs. Bioinformatic analyses were performed on the GEO datasets of radiation-induced lung injury (RILI) and BLM-induced pulmonary fibrosis (BIPF), and RNA-sequencing data of the severely damaged lung tissues. The screened differentially expressed genes (DEGs) were verified in lung epithelial cell lines by qRT-PCR assay. The injured lung tissue pathology was analyzed with H&E and Masson's staining, and immunohistochemistry staining. The macrophage chemotaxis and activity promoted by the stressed epithelial cells were determined by using a cell co-culture system. The expressions of p21 in MLE-12 and Beas-2B cells were detected by qRT-PCR, western blot, and immunofluorescence. The concentration of CCL7 in cell supernatant was measured by ELISA assay. In some experiments, Beas-2B cells were transfected with p21-siRNA or CCL7-siRNA before irradiation and/or BLM treatment. RESULTS: After the treatment of irradiation and/or BLM, the inflammatory and immune responses, chemokine-mediated signaling pathways were steadily activated in the severely injured lung, and p21 was screened out by the bioinformatic analysis and further verified to be upregulated in both mouse and human lung epithelial cell lines. The expression of P21 was positively correlated with macrophage infiltration in the injured lung tissues. Co-culturing with stressed Beas-2B cells or its conditioned medium containing CCL7 protein, U937 macrophages were actively polarized to M1-phase and their migration ability was obviously increased along with the damage degree of Beas-2B cells. Furthermore, knockdown p21 reduced CCL7 expression in Beas-2B cells and then decreased the chemotaxis of co-cultured macrophages. CONCLUSIONS: P21 promoted CCL7 release from the severely injured lung epithelial cell lines and contributed to the macrophage chemotaxis in vitro, which provides new insights for better understanding the inflammatory responses in lung injury.

Staphylococcus aureus Infection Induces the Production of the Neutrophil Chemoattractants CXCL1, CXCL2, CXCL3, CXCL5, CCL3, and CCL7 by Murine Osteoblasts.

Staphylococcus aureus is the principal causative agent of osteomyelitis, a serious bacterial infection of bone that is associated with progressive inflammatory damage. Bone-forming osteoblasts have increasingly been recognized to play an important role in the initiation and progression of detrimental inflammation at sites of infection and have been demonstrated to release an array of inflammatory mediators and factors that promote osteoclastogenesis and leukocyte recruitment following bacterial challenge. In the present study, we describe elevated bone tissue levels of the potent neutrophil-attracting chemokines CXCL1, CXCL2, CXCL3, CXCL5, CCL3, and CCL7 in a murine model of posttraumatic staphylococcal osteomyelitis. RNA sequencing (RNA-Seq) gene ontology analysis of isolated primary murine osteoblasts showed enrichment in differentially expressed genes involved in cell migration and chemokine receptor binding and chemokine activity following S. aureus infection, and a rapid increase in the expression of mRNA encoding CXCL1, CXCL2, CXCL3, CXCL5, CCL3, and CCL7, in these cells. Importantly, we have confirmed that such upregulated gene expression results in protein production with the demonstration that S. aureus challenge elicits the rapid and robust release of these chemokines by osteoblasts and does so in a bacterial dose-dependent manner. Furthermore, we have confirmed the ability of soluble osteoblast-derived chemokines to elicit the migration of a neutrophil-like cell line. As such, these studies demonstrate the robust production of CXCL1, CXCL2, CXCL3, CXCL5, CCL3, and CCL7 by osteoblasts in response to S. aureus infection, and the release of such neutrophil-attracting chemokines provides an additional mechanism by which osteoblasts could drive the inflammatory bone loss associated with staphylococcal osteomyelitis.

Chemokine CCL7 mediates trigeminal neuropathic pain via CCR2/CCR3-ERK pathway in the trigeminal ganglion of mice.

BACKGROUND: Chemokine-mediated neuroinflammation plays an important role in the pathogenesis of neuropathic pain. The chemokine CC motif ligand 7 (CCL7) and its receptor CCR2 have been reported to contribute to neuropathic pain via astrocyte-microglial interaction in the spinal cord. Whether CCL7 in the trigeminal ganglion (TG) involves in trigeminal neuropathic pain and the involved mechanism remain largely unknown. METHODS: The partial infraorbital nerve transection (pIONT) was used to induce trigeminal neuropathic pain in mice. The expression of Ccl7, Ccr1, Ccr2, and Ccr3 was examined by real-time quantitative polymerase chain reaction. The distribution of CCL7, CCR2, and CCR3 was detected by immunofluorescence double-staining. The activation of extracellular signal-regulated kinase (ERK) was examined by Western blot and immunofluorescence. The effect of CCL7 on neuronal excitability was tested by whole-cell patch clamp recording. The effect of selective antagonists for CCR1, CCR2, and CCR3 on pain hypersensitivity was checked by behavioral testing. RESULTS: Ccl7 was persistently increased in neurons of TG after pIONT, and specific inhibition of CCL7 in the TG effectively relieved pIONT-induced orofacial mechanical allodynia. Intra-TG injection of recombinant CCL7 induced mechanical allodynia and increased the phosphorylation of ERK in the TG. Incubation of CCL7 with TG neurons also dose-dependently enhanced the neuronal excitability. Furthermore, pIONT increased the expression of CCL7 receptors Ccr1, Ccr2, and Ccr3. The intra-TG injection of the specific antagonist of CCR2 or CCR3 but not of CCR1 alleviated pIONT-induced orofacial mechanical allodynia and reduced ERK activation. Immunostaining showed that CCR2 and CCR3 are expressed in TG neurons, and CCL7-induced hyperexcitability of TG neurons was decreased by antagonists of CCR2 or CCR3. CONCLUSION: CCL7 activates ERK in TG neurons via CCR2 and CCR3 to enhance neuronal excitability, which contributes to the maintenance of trigeminal neuropathic pain. CCL7-CCR2/CCR3-ERK pathway may be potential targets for treating trigeminal neuropathic pain.

Serum CCL7 Is a Novel Prognostic Biomarker of Metastatic Colorectal Cancer.

BACKGROUND/AIM: Colorectal cancer is the third most common cancer globally, and the poor prognosis of patients with metastatic colorectal cancer (mCRC) warrants urgent attention. We previously obtained 10 candidate serum biomarkers for mCRC. Our aim with this study was to determine the prognostic performance of the pre-treatment serum C-C motif chemokine ligand 7 (CCL7) concentration in patients with mCRC. PATIENTS AND METHODS: Protein concentrations of CCL7 were examined using ELISA and immunohistochemistry for serum (n=110) and surgical specimens (n=85), respectively, of patients with mCRC. The relationship between protein concentration and prognosis was examined using Cox regression analysis, receiver operator characteristic curve analysis and the Kaplan-Meier method. RESULTS: The overall survival (OS) of patients with high concentrations of serum CCL7 was significantly poorer than that of patients with low concentrations. Patients with a high CCL7 concentration in the stroma had significantly poorer outcomes than those with a low concentration. The concentrations of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 were significantly higher in the high-CCL7 group, compared to those in the low-CCL7 group. Univariate and multivariate analysis revealed that serum CCL7 concentration was a significant prognostic factor for mCRC. The combination of serum CCL and CEA concentrations was also useful in this regard (area under the curve=0.71). CONCLUSION: The combined pre-treatment serum levels of CCL7 and CEA are useful prognostic biomarkers for mCRC.

Aberrant hyperexpression of the RNA binding protein FMRP in tumors mediates immune evasion.

Many human cancers manifest the capability to circumvent attack by the adaptive immune system. In this work, we identified a component of immune evasion that involves frequent up-regulation of fragile X mental retardation protein (FMRP) in solid tumors. FMRP represses immune attack, as revealed by cancer cells engineered to lack its expression. FMRP-deficient tumors were infiltrated by activated T cells that impaired tumor growth and enhanced survival in mice. Mechanistically, FMRP's immunosuppression was multifactorial, involving repression of the chemoattractant C-C motif chemokine ligand 7 (CCL7) concomitant with up-regulation of three immunomodulators-interleukin-33 (IL-33), tumor-secreted protein S (PROS1), and extracellular vesicles. Gene signatures associate FMRP's cancer network with poor prognosis and response to therapy in cancer patients. Collectively, FMRP is implicated as a regulator that orchestrates a multifaceted barrier to antitumor immune responses.

KLF15 suppresses tumor growth and metastasis in Triple-Negative Breast Cancer by downregulating CCL2 and CCL7.

Kruppel like factor 15 (KLF15), a transcriptional factor belonging to the Kruppel-like factor (KLF) family of genes, has recently been reported as a tumor suppressor gene in breast cancer. However, the specific mechanisms by which KLF15 inhibits BrCa have not been elucidated. Here we investigated the role and mechanism of KLF15 in triple-negative breast cancer (TNBC). KLF15 expression and methylation were detected by RT-qPCR, RT-PCR and methylation-specific PCR in breast cancer cell lines and tissues. The effects of KLF15 on TNBC cell functions were examined via various cellular function assays. The specific anti-tumor mechanisms of KLF15 were further investigated by RNA sequence, RT-qPCR, Western blotting, luciferase assay, ChIP, and bioinformatics analysis. As the results showed that KLF15 is significantly downregulated in breast cancer cell lines and tissues, which promoter methylation of KLF15 partially contributes to. Exogenous expression of KLF15 induced apoptosis and G2/M phase cell cycle arrest, suppressed cell proliferation, metastasis and in vivo tumorigenesis of TNBC cells. Mechanism studies revealed that KLF15 targeted and downregulated C-C motif chemokine ligand 2 (CCL2) and CCL7. Moreover, transcriptome and metabolome analysis revealed that KLF15 is involved in key anti-tumor regulatory and metabolic pathways in TNBC. In conclusion, KLF15 suppresses cell growth and metastasis in TNBC by downregulating CCL2 and CCL7. KLF15 may be a prognostic biomarker in TNBC.

Connexin 37 Regulates the Kv1.3 Pathway and Promotes the Development of Atherosclerosis.

Objective: To investigate the mechanism of Connexin 37 (Cx37) and Kv1.3 pathways in atherosclerosis (AS). Methods: ApoE-/- mice were given a high-fat diet to establish atherosclerosis (AS) model, and macrophages in mice were isolated and extracted to transfect Cx37 vectors with silencing or overexpressing, and Kv1.3 pathway blockers were used to inhibit the pathway activity. The indexes of body weight, blood glucose, and blood lipid of mice were collected. The protein and mRNA expression levels of Cx37 and Kv1.3 were detected by reverse transcription-PCR (RT-PCR), Western blot, and immunofluorescence technique. Oil red O staining was used to observe plaque area. Masson staining was used to detect collagen content. The concentrations of chemokine CCL7 were quantified using the ELISA kits. CCK8 was used to detect cell proliferation. Results: Cx37 and Kv1.3 were highly expressed in macrophages of AS mice, and the expression of Kv1.3 and CCL7 decreased after Cx37 was silenced, and the proliferation of macrophages was also decreased. Wild-type mice and AS model mice were treated with Cx37 overexpression vectors and Kv1.3 pathway blocking, and it was found that Cx37 overexpression could improve the blood lipid and blood glucose levels and increase the area of AS in AS mice. However, blocking the activity of Kv1.3 pathway can reduce the levels of blood lipid and blood glucose, increase the body weight of mice, and reduce the area of AS mice. Blocking the activity of Kv1.3 pathway can slow down the plaque development of AS mice and make its indexes close to wild-type mice. And the use of Kv1.3 pathway blockers on the basis of overexpression of Cx37 indicated that inhibition of Kv1.3 pathway activity did not affect the expression of Cx37, but could inhibit the collagen content in the plaque area of AS mice, inhibit the expression of chemokine CCL7, and reverse the effect of Cx37 overexpression. Conclusion: Cx37 can improve the activity of macrophages by regulating the expression of chemokines and the activity of Kv1.3 pathway in AS mice, and enrich macrophages in inflammatory tissues and expand the area of plaque formation.

The role of CCL2, CCL7, ICAM-1, and VCAM-1 in interaction of endothelial cells and natural killer cells.

Natural killer (NK) cell-based therapy has been studied for the treatment of patients with cancers, but the inadequate infiltration of NK cells into solid tumors remains a big challenge to its clinical application. In this study, we examined the interaction between NK cells and endothelial cells, which might play a major role in NK cell homing to solid tumors. We found that endothelial cells were activated by TNF-α and IL-1ß, which were produced by tumor-associated CD11b+ cells, which included F4/80+ macrophages. TNF-α-treated endothelial cells increased NK cell migration by producing CCL2 and CCL7, which was proved by transwell and imaging assays. TNF-α-treated endothelial cells adhered well to NK cells, which was due to a TNF-α-induced increase in ICAM-1 and VCAM-1 expression on endothelial cells. Imaging data confirmed that TNF-α-treated endothelial cells transfected with ICAM-1 or VCAM-1 siRNAs did not establish stable contacts with NK cells. Taken together, our data suggest that CCL2, CCL7, ICAM-1, and VCAM-1 expressed by endothelial cells will be potential targets to guide adequate interaction with NK cells, which is a crucial step for NK cell homing to the tumor microenvironment.

3,5-Dicaffeoylquinic acid attenuates microglial activation-mediated inflammatory pain by enhancing autophagy through the suppression of MCP3/JAK2/STAT3 signaling.

Microglial activation in the spinal cord contributes to the development of inflammatory pain. Monocyte chemotactic protein 3 (MCP3) can induce microglial activation, resulting in increased pain sensitivity; however, the underlying mechanism remains poorly understood. 3,5-dicaffeoylquinic acid (3,5-DCQA) has shown protective effects against inflammation-related diseases, but the effect of 3,5-DCQA on microglial activation and inflammatory pain is not evaluated. This study aimed to investigate the effects of 3,5-DCQA on microglial activation-induced inflammatory pain. Furthermore, the underlying mechanism inhibited by 3,5-DCQA via MCP3 suppression was studied. To induce microglial activation, LPS was treated in BV2 microglial cells. The LPS-induced microglial activation and pro-inflammatory cytokines production were significantly reduced by 3,5-DCQA treatment in BV2 cells. Moreover, 3,5-DCQA suppressed LPS-induced MCP3 expression, resulting in reduced phosphorylation of JAK2/STAT3. Interestingly, the suppressed JAK2/STAT3 signaling enhanced autophagy induction in BV2 cells. The increased autophagy by 3,5-DCQA and knockout of MCP3 inhibited LPS-induced inflammatory response in BV2 cells. To establish the inflammatory pain, CFA was injected into the right paw of mice. The CFA-induced pain hypersensitivity and foot swelling were attenuated by the oral administration of 3,5-DCQA. Moreover, CFA-induced microglial activation was reduced and the autophagy markers were recovered in the spinal cord of 3,5-DCQA-administered mice. Similar results were observed in cultured primary microglia. Our findings indicate that 3,5-DCQA attenuates inflammation-mediated pain hypersensitivity by enhancing autophagy through inhibition of MCP3-induced JAK2/STAT3 signaling. Therefore, 3,5-DCQA could be a potential therapeutic agent for alleviating inflammatory pain.

CCL7 as a novel inflammatory mediator in cardiovascular disease, diabetes mellitus, and kidney disease.

Chemokines are key components in the pathology of chronic diseases. Chemokine CC motif ligand 7 (CCL7) is believed to be associated with cardiovascular disease, diabetes mellitus, and kidney disease. CCL7 may play a role in inflammatory events by attracting macrophages and monocytes to further amplify inflammatory processes and contribute to disease progression. However, CCL7-specific pathological signaling pathways need to be further confirmed in these chronic diseases. Given the multiple redundancy system among chemokines and their receptors, further experimental and clinical studies are needed to clarify whether direct CCL7 inhibition mechanisms could be a promising therapeutic approach to attenuating the development of cardiovascular disease, diabetes mellitus, and kidney disease.

LINC01094/SPI1/CCL7 Axis Promotes Macrophage Accumulation in Lung Adenocarcinoma and Tumor Cell Dissemination.

Objective: Infiltration of tumor-associated macrophages is closely linked to the malignant development of human cancers. This research studies the function of C-C motif chemokine ligand 7 (CCL7) in the macrophage accumulation in lung adenocarcinoma (LUAD) and the underpinning mechanism. Methods: The expression profile of CCL7 in LUAD and its correlations with patient's prognosis and macrophage infiltration were predicted via bioinformatics systems. Artificial up- or downregulation of CCL7 was induced in LUAD cells to explore its function in the mobility, EMT of cancer cells, and migration of M2 macrophages. Cancer cells were implanted in NOD/SCID mice to induce xenograft tumors. The CCL7-related transcription factors or factors were predicted by bioinformatic tools, and the molecular interactions were confirmed by immunoprecipitation or luciferase assays. Results: CCL7 was highly expressed in LUAD and linked to increased TAM infiltration. Knockdown of CCL7 suppressed the chemotaxis and M2 skewing of macrophages, and it blocked the EMT and mobility of LUAD cells. CCL7 downregulation also suppressed macrophage infiltration in xenograft tumors in mice. Spi-1 proto-oncogene (SPI1) was confirmed as an upstream factor activating CCL7 transcription, and LINC01094 was found to bind to SPI1 to promote its nuclear translocation. Upregulation of SPI1 restored the chemotactic migration and M2 polarization of macrophages in LUAD cells. Conclusion: This paper reveals that LINC01094 binds to SPI1 to promote its nuclear translocation, which further activates CCL7 transcription by binding to its promoter, leading to M2 macrophage accumulation and dissemination of tumor cells.

CCL7 playing a dominant role in recruiting early OCPs to facilitate osteolysis at metastatic site of colorectal cancer.

BACKGROUND: Chemoattractant is critical to recruitment of osteoclast precursors and stimulates tumor bone metastasis. However, the role of chemoattractant in bone metastasis of colorectal cancer (CRC) is still unclear. METHODS: Histochemistry analysis and TRAP staining were utilized to detect the bone resorption and activation of osteoclasts (OCs) after administration of CCL7 neutralizing antibody or CCR1 siRNA. qRT-PCR analysis and ELISA assay were performed to detect the mRNA level and protein level of chemoattractant. BrdU assay and Tunel assay were used to detect the proliferation and apoptosis of osteoclast precursors (OCPs). The migration of OCPs was detected by Transwell assay. Western blots assay was performed to examine the protein levels of pathways regulating the expression of CCL7 or CCR1. RESULTS: OCPs-derived CCL7 was significantly upregulated in bone marrow after bone metastasis of CRC. Blockage of CCL7 efficiently prevented bone resorption. Administration of CCL7 promoted the migration of OCPs. Lactate promoted the expression of CCL7 through JNK pathway. In addition, CCR1 was the most important receptor of CCL7. CONCLUSION: Our study indicates the essential role of CCL7-CCR1 signaling for recruitment of OCPs in early bone metastasis of CRC. Targeting CCL7 or CCR1 could restore the bone volume, which could be a potential therapeutical target. Video Abstract.

Bindarit Reduces Bone Loss in Ovariectomized Mice by Inhibiting CCL2 and CCL7 Expression via the NF-κB Signaling Pathway.

OBJECTIVE: To investigate the changes in proinflammatory cytokines and chemokines, namely, C-C motif ligand (CCL) 2 and CCL7, in postmenopausal osteoporosis (PMOP) and to develop a new drug, bindarit (Bnd), for PMOP in an ovariectomized (OVX) mouse model. METHODS: Bone marrow macrophages (BMMs) from the femurs of five women with PMOP and five premenopausal women without osteoporosis were detected by RNA sequencing. BMMs from mice were differentiated into osteoclasts and treated with a synthetic inhibitor of CCL2 and CCL7, Bnd, or 17 beta estradiol (E2 ). Mouse BMMs were differentiated into osteoclasts with or without Bnd for 7 days and analyzed by RNA sequencing. Osteoblasts of mice were induced to undergo osteoblastogenesis and treated with Bnd. OVX mice were treated with E2 or Bnd after surgery. The protein and mRNA expression of CCL2 and CCL7 was detected using immunostaining and qPCR, respectively, in OVX and aged mice and in cells cultured in vitro. Osteoclast formation was detected using a tartrate-resistant acid phosphatase (TRAP) assay in vitro and in vivo. Alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) were detected using immunostaining to evaluate osteogenesis. Microcomputed tomography was conducted to analyze trabecular bone parameters, the structure model index, bone mineral density and other variables. Nuclear factor-κB (NF-κB) signaling pathway-related protein phosphorylation of IKKα/ß (p-IKKα/ß) and p-NFκB p65 was examined using western blotting. RESULTS: CCL2, CCL7 and their receptor of C-C chemokine receptor-2 (CCR2), and the NF-κB signaling pathway, were significantly increased in women with PMOP. CCL2 and CCL7 protein and mRNA expression was increased in OVX mice and aged female mice, but the increases were attenuated by E2 and Bnd. E2 and Bnd effectively inhibited osteoclastogenesis and the protein expression of CCL2 and CCL7 both in vitro and in vivo and reduced bone loss in OVX mice. Bnd did not affect the mineralization of osteoblasts directly in vitro but reduced bone turnover in vivo. p-IKKα/ß and p-NFκB p65 levels were increased in BMMs of mice after differentiation into osteoclasts but were significantly decreased by Bnd. CONCLUSION: The proinflammatory cytokines and chemokines CCL2, CCL7 and CCR2 were correlated with PMOP. Bnd attenuated the increases in CCL2 and CCL7 levels to affect osteoporosis in OVX mice via the NFκB signaling pathway. Thus, Bnd may be useful as a new therapeutic for the prevention of PMOP.

CCL7 and TGF-ß secreted by MSCs play opposite roles in regulating CRC metastasis in a KLF5/CXCL5-dependent manner.

CXCL5 is overexpressed in colorectal cancer (CRC) and promotes distant metastasis and angiogenesis of tumors; however, the underlying mechanism that mediates CXCL5 overexpression in CRC remains unclear. Here, we successfully extracted and identified primary mesenchymal stromal cells (MSCs) and verified the promoting effects of tumor-associated MSCs on CRC proliferation and metastasis in vivo and in vitro. We found that MSCs not only promoted the expression of CXCL5 by secreting CCL7 but also secreted TGF-ß to inhibit this process. After secretion, CCL7/CCR1 activated downstream CBP/P300 to acetylate KLF5 to promote CXCL5 transcription, while TGF-ß reversed the effect of KLF5 on transcription activation by regulating SMAD4. Taken together, our results indicate that MSCs in the tumor microenvironment promoted the progression and metastasis of CRC and regulated the expression of CXCL5 in CRC cells by secreting CCL7 and TGF-ß. KLF5 is the key site of these processes and plays a dual role in CXCL5 regulation. MSCs and their secreted factors may serve as potential therapeutic targets in the tumor environment.

Immunosuppressive tumor microenvironment in uterine serous carcinoma via CCL7 signal with myeloid-derived suppressor cells.

Serous carcinoma of the uterus (USC) is a pathological subtype of high-grade endometrial cancers, with no effective treatment for advanced cases. Since such refractory tumors frequently harbor antitumor immune tolerance, many immunotherapies have been investigated for various malignant tumors using immuno-competent animal models mimicking their local immunities. In this study, we established an orthotopic mouse model of high-grade endometrial cancer and evaluated the local tumor immunity to explore the efficacy of immunotherapies against USC. A multivariate analysis of 62 human USC cases revealed that the tumor-infiltrating cell status, few CD8+ cells and abundant myeloid-derived suppressor cells (MDSCs), was an independent prognostic factor (P < 0.005). A murine endometrial cancer cell (mECC) was obtained from C57BL/6 mice via endometrium-specific deletion of Pten and Tp53, and another high-grade cell (HPmECC) was established by further overexpressing Myc in mECCs. HPmECCs exhibited higher capacities of migration and anchorage-independent proliferation than mECCs (P < 0.01, P < 0.0001), and when both types of cells were inoculated into the uterus of C57BL/6 mice, the prognosis of mice bearing HPmECC-derived tumors was significantly poorer (P < 0.001). Histopathological analysis of HPmECC orthotopic tumors showed serous carcinoma-like features with prominent tumor infiltration of MDSCs (P < 0.05), and anti-Gr-1 antibody treatment significantly prolonged the prognosis of HPmECC-derived tumor-bearing mice (P < 0.05). High CCL7 expression was observed in human USC and HPmECC, and MDSCs migration was promoted in a CCL7 concentration-dependent manner. These results indicate that antitumor immunity is suppressed in USC due to increased number of tumor-infiltrating MDSCs via CCL signal.

ROS-induced PADI2 downregulation accelerates cellular senescence via the stimulation of SASP production and NFκB activation.

Cellular senescence is closely related to tissue aging including bone. Bone homeostasis is maintained by the tight balance between bone-forming osteoblasts and bone-resorbing osteoclasts, but it undergoes deregulation with age, causing age-associated osteoporosis, a main cause of which is osteoblast dysfunction. Oxidative stress caused by the accumulation of reactive oxygen species (ROS) in bone tissues with aging can accelerate osteoblast senescence and dysfunction. However, the regulatory mechanism that controls the ROS-induced senescence of osteoblasts is poorly understood. Here, we identified Peptidyl arginine deiminase 2 (PADI2), a post-translational modifying enzyme, as a regulator of ROS-accelerated senescence of osteoblasts via RNA-sequencing and further functional validations. PADI2 downregulation by treatment with H2O2 or its siRNA promoted cellular senescence and suppressed osteoblast differentiation. CCL2, 5, and 7 known as the elements of the senescence-associated secretory phenotype (SASP) which is a secretome including proinflammatory cytokines and chemokines emitted by senescent cells and a representative feature of senescence, were upregulated by H2O2 treatment or Padi2 knockdown. Furthermore, blocking these SASP factors with neutralizing antibodies or siRNAs alleviated the senescence and dysfunction of osteoblasts induced by H2O2 treatment or Padi2 knockdown. The elevated production of these SASP factors was mediated by the activation of NFκB signaling pathway. The inhibition of NFκB using the pharmacological inhibitor or siRNA effectively relieved H2O2 treatment- or Padi2 knockdown-induced senescence and osteoblast dysfunction. Together, our study for the first time uncover the role of PADI2 in ROS-accelerated cellular senescence of osteoblasts and provide new mechanistic and therapeutic insights into excessive ROS-promoted cellular senescence and aging-related bone diseases.

Oxidative stress induces inflammation of lens cells and triggers immune surveillance of ocular tissues.

Recent reports have challenged the notion that the lens is immune-privileged. However, these studies have not fully identified the molecular mechanism(s) that promote immune surveillance of the lens. Using a mouse model of targeted glutathione (GSH) deficiency in ocular surface tissues, we have investigated the role of oxidative stress in upregulating cytokine expression and promoting immune surveillance of the eye. RNA-sequencing of lenses from postnatal day (P) 1-aged Gclcf/f;Le-CreTg/- (KO) and Gclcf/f;Le-Cre-/- control (CON) mice revealed upregulation of many cytokines (e.g., CCL4, GDF15, CSF1) and immune response genes in the lenses of KO mice. The eyes of KO mice had a greater number of cells in the aqueous and vitreous humors at P1, P20 and P50 than age-matched CON and Gclcw/w;Le-CreTg/- (CRE) mice. Histological analyses revealed the presence of innate immune cells (i.e., macrophages, leukocytes) in ocular structures of the KO mice. At P20, the expression of cytokines and ROS content was higher in the lenses of KO mice than in those from age-matched CRE and CON mice, suggesting that oxidative stress may induce cytokine expression. In vitro administration of the oxidant, hydrogen peroxide, and the depletion of GSH (using buthionine sulfoximine (BSO)) in 21EM15 lens epithelial cells induced cytokine expression, an effect that was prevented by co-treatment of the cells with N-acetyl-l-cysteine (NAC), a antioxidant. The in vivo and ex vivo induction of cytokine expression by oxidative stress was associated with the expression of markers of epithelial-to-mesenchymal transition (EMT), α-SMA, in lens cells. Given that EMT of lens epithelial cells causes posterior capsule opacification (PCO), we propose that oxidative stress induces cytokine expression, EMT and the development of PCO in a positive feedback loop. Collectively these data indicate that oxidative stress induces inflammation of lens cells which promotes immune surveillance of ocular structures.

Glioma-derived CCL2 and CCL7 mediate migration of immune suppressive CCR2+/CX3CR1+ M-MDSCs into the tumor microenvironment in a redundant manner.

Glioblastoma (GBM) is the most common and malignant primary brain tumor, resulting in poor survival despite aggressive therapies. GBM is characterized in part by a highly heterogeneous and immunosuppressive tumor microenvironment (TME) made up predominantly of infiltrating peripheral immune cells. One significant immune cell type that contributes to glioma immune evasion is a population of immunosuppressive, hematopoietic cells, termed myeloid-derived suppressor cells (MDSCs). Previous studies suggest that a potent subset of myeloid cells, expressing monocytic (M)-MDSC markers, distinguished by dual expression of chemokine receptors CCR2 and CX3CR1, utilize CCR2 to infiltrate into the TME. This study evaluated the T cell suppressive function and migratory properties of CCR2+/CX3CR1+ MDSCs. Bone marrow-derived CCR2+/CX3CR1+ cells adopt an immune suppressive cell phenotype when cultured with glioma-derived factors. Recombinant and glioma-derived CCL2 and CCL7 induce the migration of CCR2+/CX3CR1+ MDSCs with similar efficacy. KR158B-CCL2 and -CCL7 knockdown murine gliomas contain equivalent percentages of CCR2+/CX3CR1+ MDSCs compared to KR158B gliomas. Combined neutralization of CCL2 and CCL7 completely blocks CCR2-expressing cell migration to KR158B cell conditioned media. CCR2+/CX3CR1+ cells are also reduced within KR158B gliomas upon combination targeting of CCL2 and CCL7. High levels of CCL2 and CCL7 are also associated with negative prognostic outcomes in GBM patients. These data provide a more comprehensive understanding of the function of CCR2+/CX3CR1+ MDSCs and the role of CCL2 and CCL7 in the recruitment of these immune suppressive cells and further support the significance of targeting this chemokine axis in GBM.