R-spondin 2 mediates neutrophil egress into the alveolar space through increased lung permeability

Endothelial RSPO3 mediates pulmonary endothelial regeneration by LGR4-dependent activation of β-catenin and ILK signaling pathways after inflammatory vascular injury

Endothelial repair is essential for restoring tissue fluid homeostasis following lung injury. R-spondin3 (RSPO3), a secreted protein mainly produced by endothelial cells (ECs), has shown its protective effect on endothelium. However, the specific mechanisms remain unknown. To explore whether and how RSPO3 regulates endothelial regeneration after inflammatory vascular injury, the role of RSPO3 in sepsis-induced pulmonary endothelial injury was investigated in EC-specific RSPO3 knockdown, inducible EC-specific RSPO3 deletion mice, EC-specific RSPO3 overexpression mice, systemic RSPO3-administration mice, in isolated mouse lung vascular endothelial cells (MLVECs), and in plasma from septic patients. Here we show that plasma RSPO3 levels are decreased in septic patients and correlated with endothelial injury markers and PaO2/FiO2 index. Both pulmonary EC-specific knockdown of RSPO3 and inducible EC-specific RSPO3 deletion inhibit pulmonary ECs proliferation and exacerbate ECs injury, whereas intra-pulmonary EC-specific RSPO3 overexpression promotes endothelial recovery and attenuates ECs injury during endotoxemia. We show that RSPO3 mediates pulmonary endothelial regeneration by a LGR4-dependent manner. Except for β-catenin, integrin-linked kinase (ILK)/Akt is also identified as a novel downstream effector of RSPO3/LGR4 signaling. These results conclude that EC-derived RSPO3 mediates pulmonary endothelial regeneration by LGR4-dependent activation of β-catenin and ILK signaling pathways after inflammatory vascular injury.

The biological functions and related signaling pathways of SPON2

Spondin-2 (SPON2), also referred to as M-spondin or DIL-1, is a member of the extracellular matrix protein family known as Mindin-F-spondin (FS). SPON2 can be used as a broad-spectrum tumor marker for more than a dozen tumors, mainly prostate cancer. Meanwhile, SPON2 is also a potential biomarker for the diagnosis of certain non-tumor diseases. Additionally, SPON2 plays a pivotal role in regulating tumor metastasis and progression. In normal tissues, SPON2 has a variety of biological functions represented by promoting growth and development and cell proliferation. This paper presents a comprehensive overview of the regulatory mechanisms, diagnostic potential as a broad-spectrum biomarker, diverse biological functions, involvement in various signaling pathways, and clinical applications of SPON2.

Serum Spondin-2 expression, tumor invasion, and antitumor immune response in patients with cervical cancer

BACKGROUND

Cervical cancer is a gynecological malignancy common in middle-aged and older patients, with a high mortality rate. Spondin-2 is an extracellular matrix protein that involved in innate and acquired immune responses. Herein, we investigated the relationship between serum Spondin-2 expression, tumor invasion and infiltration, and immune response in patients with cervical cancer and provided a theoretical basis for clinical practice.

AIM

To investigate the relationship between serum Spondin-2 expression and cervical cancer-related indicators.

METHODS

Overall, 147 patients with cervical cancer who were admitted to our institution between January 2019 and August 2019 were assigned to the cervical cancer group, and 92 patients with benign uterine lesions and 86 healthy individuals were assigned to the benign and control groups, respectively. In each group, serum Spondin-2 expression was measured, and the receiver operating characteristic (ROC) curve was determined. Patients with cervical cancer were classified into high or low Spondin-2 groups depending on the Spondin-2 threshold value used for diagnosing cervical cancer. Patient’s clinical data were collected to compare the clinicopathologic characteristics, immune cytokine levels, and prognosis of patients with varying Spondin-2 expression levels.

RESULTS

The expression level of serum Spondin-2 was significantly higher in the cervical cancer group than in the benign and control groups (P < 0.05). According to the ROC curve, the cutoff value of Spondin-2 used in the diagnosis of cervical carcinoma was 25.68 ± 7.11 μg/L. The proportion of patients with Federation of Gynecology and Obstetrics stage III, nerve invasion, vascular invasion, and lymph node metastasis was higher in the high Spondin-2 group than in the low Spondin-2 group (P < 0.05). Interleukin-5 (IL-5) and IL-4 Levels were higher in the high Spondin-2 group than in the low Spondin-2 group. In contrast, IL-2 and tumor necrosis factor-α levels were lower in the high Spondin-2 group than in the low Spondin-2 group (P < 0.05). After 3 years of follow-up, progression-free survival and overall survival were significantly shorter in the high Spondin-2 group than in the low Spondin-2 group (P < 0.05).

CONCLUSION

The expression of serum Spondin-2 is upregulated in patients with cervical carcinoma and is related to tumor invasion and infiltration, antitumor immune response, and prognosis.

R-Spondin2, a Positive Canonical WNT Signaling Regulator, Controls the Expansion and Differentiation of Distal Lung Epithelial Stem/Progenitor Cells in Mice

The lungs have a remarkable ability to regenerate damaged tissues caused by acute injury. Many lung diseases, especially chronic lung diseases, are associated with a reduced or disrupted regeneration potential of the lungs. Therefore, understanding the underlying mechanisms of the regenerative capacity of the lungs offers the potential to identify novel therapeutic targets for these diseases. R-spondin2, a co-activator of WNT/β-catenin signaling, plays an important role in embryonic murine lung development. However, the role of Rspo2 in adult lung homeostasis and regeneration remains unknown. The aim of this study is to determine Rspo2 function in distal lung stem/progenitor cells and adult lung regeneration. In this study, we found that robust Rspo2 expression was detected in different epithelial cells, including airway club cells and alveolar type 2 (AT2) cells in the adult lungs. However, Rspo2 expression significantly decreased during the first week after naphthalene-induced airway injury and was restored by day 14 post-injury. In ex vivo 3D organoid culture, recombinant RSPO2 promoted the colony formation and differentiation of both club and AT2 cells through the activation of canonical WNT signaling. In contrast, Rspo2 ablation in club and AT2 cells significantly disrupted their expansion capacity in the ex vivo 3D organoid culture. Furthermore, mice lacking Rspo2 showed significant defects in airway regeneration after naphthalene-induced injury. Our results strongly suggest that RSPO2 plays a key role in the adult lung epithelial stem/progenitor cells during homeostasis and regeneration, and therefore, it may be a potential therapeutic target for chronic lung diseases with reduced regenerative capability.

Il4ra-independent vaginal eosinophil accumulation following helminth infection exacerbates epithelial ulcerative pathology of HSV-2 infection

How helminths influence the pathogenesis of sexually transmitted viral infections is not comprehensively understood. Here, we show that an acute helminth infection (Nippostrongylus brasiliensis [Nb]) induced a type 2 immune profile in the female genital tract (FGT). This leads to heightened epithelial ulceration and pathology in subsequent herpes simplex virus (HSV)-2 infection. This was IL-5-dependent but IL-4 receptor alpha (Il4ra) independent, associated with increased FGT eosinophils, raised vaginal IL-33, and enhanced epithelial necrosis. Vaginal eosinophil accumulation was promoted by IL-33 induction following targeted vaginal epithelium damage from a papain challenge. Inhibition of IL-33 protected against Nb-exacerbated HSV-2 pathology. Eosinophil depletion reduced IL-33 release and HSV-2 ulceration in Nb-infected mice. These findings demonstrate that Nb-initiated FGT eosinophil recruitment promotes an eosinophil, IL-33, and IL-5 inflammatory circuit that enhances vaginal epithelial necrosis and pathology following HSV-2 infection. These findings identify a mechanistic framework as to how helminth infections can exacerbate viral-induced vaginal pathology.