Studies have begun to emerge showing the protumor effects of tumor-associated neutrophils (TANs) in tumorigenesis, which may involve dysfunction of NK cells. However, the mechanism through which these rebellious neutrophils modulate NK cell immunity in tumor-bearing state remains unclear. In the present study, we demonstrate that neutrophils can impair the cytotoxicity and infiltration capability of NK cells, and downregulate CCR1 resulting in the weakened infiltration capability of NK cells. Moreover, neutrophils can decrease the responsiveness of NK-activating receptors, NKp46 and NKG2D. Mechanistically, enhanced PD-L1 on neutrophils and PD-1 on NK cells, and subsequent PD-L1/PD-1 interactions were the main mechanisms determining the suppression of neutrophils in NK cell immunity. G-CSF/STAT3 pathway was responsible for PD-L1 upregulation on neutrophils, while IL-18 was essential for PD-1 enhancement on NK cells. The crosstalk between neutrophils and NK cells was cell-cell interaction-dependent. These findings suggest that neutrophils can suppress the antitumor immunity of NK cells in tumor-bearing status through the PD-L1/PD-1 axis, highlighting the importance of PD-L1/PD-1 in the inhibitory effect of neutrophils on NK cells. Targeting G-CSF/STAT3 and IL-18 signaling pathway may be potential strategies to inhibit residual tumor in tumor therapy.

No abstract

Preeclampsia (PE) remains a leading cause of maternal and neonatal morbidity and mortality. Numerous studies have shown that women with PE develop autoantibody, termed angiotensin II type 1 receptor autoantibody (AT1-AA), and key features of the disease result from it. Emerging evidence has indicated that inflammatory cell necrosis, such as pyroptosis, could lead to autoantigen exposure and stimulate autoantibody production. Caspase-1, the central enzyme of inflammasome and key target of pyroptosis, may play roles in AT1R exposure and AT1-AA production. Exploring endogenous regulator that could inhibit AT1-AA production by targeting pyroptosis will be essential for treating PE. Lipoxin A 4 (LXA 4), endogenous dual anti-inflammatory and proresolving lipid mediator, may inhibit AT1-AA production via modulating caspase-1. Thus, we explore whether caspase-1 is essential for AT1-AA production and LXA 4 inhibits AT1-AA via modulating caspase-1. PE patients and mice developed AT1-AA associated with caspase-1 activation. Caspase-1 deletion leaded to AT1-AA decrease in PE mice. Consistent with these findings, we confirmed caspase-1 activation, trophoblast pyroptosis and AT1R exposure in PE mice and trophoblast model, while caspase-1 deficiency showed decreased trophoblast pyroptosis and AT1R exposure in vitro and in vivo. Interestingly, LXA 4 could suppress AT1-AA production via regulating caspase-1 as well as enhancing phagocytosis of dead trophoblasts by macrophages. These results suggest that caspase-1 promotes AT1-AA production via inducing trophoblast pyroptosis and AT1R exposure, while LXA 4 suppresses AT1-AA production via modulating caspase-1, supporting caspase-1 serving as a therapeutic target for attenuating AT1-AA and LXA 4 protecting patients from AT1-AA and PE.

Unresolved inflammation, due to insufficient production of proresolving anti-inflammatory lipid mediators, can lead to tumorigenesis. Among these mediators, lipoxin A4 (LXA4) has potent anti-carcinogenic properties, and may serve as key target for modulating inflammation-associated cancer like colorectal cancer. The purpose of present study was to clarify the roles of LXA4 in colorectal cancer. We investigated the effects and underlying mechanisms of LXA4 in colorectal cancer and its relationship with tumor-associated inflammation and immune microenvironment by employing clinical samples and mouse colorectal cancer cell line CT26-bearing tumor model as well as colorectal cancer cells. It was found that colorectal cancer is associated with dysregulation of immune microenvironment and deficiency of LXA4 that could play different roles at different stages of tumor growth: inhibiting early but promoting late tumor growth. Analysis of peripheral immune cells in subcutaneous xenograft mice model disclosed that early LXA4 treatment induced lymphocytes and inhibited neutrophils and monocytes, while late LXA4 treatment induced neutrophils but inhibited lymphocytes. Detailed analysis of tumor microenvironment revealed that early LXA4 treatment could inhibit inflammatory mediators expressions and leukocytes infiltration into tumor. Furthermore, LXA4 could suppress the expressions of p-ERK, p-P38 and NF-κB in subcutaneous xenograft. Additionally, LXA4 could inhibit the proliferation and migration of colorectal cancer cells, and, meanwhile, inhibit the proliferation and migration of colorectal cancer cells stimulated by activated macrophage-conditioned media. These findings suggest that colorectal cancer is associated with a deficiency of LXA4 that could suppress colorectal cancer via modulating tumor-associated inflammation and immune microenvironment as well as inhibiting colorectal cancer cell development.

Inflammation dysregulation in placenta is implicated in the pathogenesis of numerous pregnancy complications. Glucocorticoids (GCs), universally considered anti-inflammatory, can also exert proinflammatory actions under some conditions, whereas whether and how GCs promote placental inflammation have not been intensively investigated. In this paper we report the opposing regulation of rat placental inflammation by synthetic GC dexamethasone (Dex). When Dex was subcutaneously injected 1 h after we administered an intraperitoneal lipopolysaccharide (LPS) challenge, neutrophil infiltration and proinflammatory Il1b, Il6, and Tnfa expression in rat placenta were significantly reduced. In contrast, Dex pretreatment for 24 h potentiated rat placental proinflammatory response to LPS and delayed inflammation resolution, which involved MAPKs and NF-kappaB activation. Mechanically, Dex pretreatment promoted 5-lipoxygenase (ALOX5) activation and increased leukotriene B4 production, whereas it inhibited the anti-inflammatory and proresolving lipid mediator lipoxin A4 (LXA4) biosynthesis in rat placenta via downregulating ALOX15 and ALOX15B expression. Moreover, LXA4 supplementation dampened Dex-potentiated placental inflammation and suppressed Dex-mediated ALOX5 activation in vivo and in vitro. Taken together, these findings suggest that GCs exposure could promote placental inflammation initiation and delay resolution via disrupting LXA4 biosynthesis.

The pathogenesis of preeclampsia (PE) involves a number of biological processes that may be directly or indirectly affected by glucocorticoid (GC) and vitamin D. GC exposure increases the risk of PE, and 1,25-dihydroxyvitamin D (1,25-(OH)D) deficiency may result in PE. The purpose of the present study was to confirm the involvement of GC/1,25-(OH)D axis in the pathogenesis of PE. In the study, cortisol levels of PE patients were found to be higher than that of non-complicated pregnancies, while 1,25-(OH)D were decreased in both PE women and GC-induced PE rats. Mechanically, GC reduced 1,25-(OH)D levels via disturbing its biosynthetic and catabolic enzymes, including Cyp3a1,Cyp24a1 and Cyp27b1, especially enhancing the expressions of Cyp3a1, the dominant enzyme for vitamin D degeneration. Moreover, replenishing 1,25-(OH)D ameliorated the symptoms and placental oxidative stress of GC-induced rat PE. The protective actions of 1,25-(OH)D might be explained by its roles in antagonizing the effects of GC on trophoblast proliferation and apoptosis. Together, these findings suggest that GC exposure could lead to PE via dampening 1,25-(OH)D biosynthesis, and GC/1,25-(OH)D axis might represent a common pathway through which PE occurs.

To the best of our knowledge, this is the first time to generate fluorescent HBV virions with biarsenical labelling and to visualize their trafficking in living cells. The fluorescent HBV may become one highly valuable tool for further studying detailed dynamic processes of HBV life cycle and interaction of HBV with host in live-imaging approach.

The pathogenesis of preeclampsia (PE) involves several pathophysiological processes that may be affected by glucocorticoid (GC). We confirmed previously that GC exposure could result in PE, while PE is linked to a deficiency of lipoxin A 4 (LXA 4), an endogenous dual anti-inflammatory and proresolving mediator. The present study was to investigate whether GC exposure induces PE via dampening LXA 4. In the study, cortisol levels of PE women were higher than those of normal pregnancies, LXA 4 levels were downregulated in both PE patients and GC-mediated PE rats, and leukotriene B 4 (LTB 4) levels were upregulated in both PE patients and GC-mediated PE rats. Moreover, cortisol levels were negatively correlated to LXA 4 levels, while positively correlated to LTB 4 levels in PE patients. Mechanically, GC downregulated LXA 4 via disturbing its biosynthetic enzymes, including ALOX15, ALOX5B and ALOX5, especially activating ALOX5, the key enzyme for class switching between LXA 4 and LTB 4. Importantly, replenishing LXA 4 could ameliorate PE-related symptoms and placental oxidative stress in PE rat model induced by GC. Moreover, LXA 4 could inhibit GC-mediated ALOX5 activation and LTB 4 increase, and also suppress 11b-HSD2 expression and corticosterone upregulation. The protective actions of LXA 4 might be explained by its roles in antagonizing the adverse effects of GC on trophoblast development. Together, our findings indicate that GC exposure could contribute to PE through dampening LXA 4 , and GC/LXA 4 axis may represent a common pathway through which PE occurs.