Angiopathic activity of LRG1 is induced by the IL-6/STAT3 pathway

Leucine-Rich Alpha-2-Glycoprotein 1 Promotes Metastatic Colorectal Cancer Growth Through Human Epidermal Growth Factor Receptor 3 Signaling

BACKGROUND & AIMS

Therapy failure in patients with metastatic colorectal cancer (mCRC, ∼80% occur in the liver) remains an overarching challenge. Preclinical studies demonstrated that human epidermal growth factor receptor 3 (HER3) promotes colorectal cancer (CRC) cell survival, but therapies blocking the neuregulin-induced canonical HER3 signaling have made little impact in the clinic. Recent studies suggest that the liver microenvironment promotes CRC growth by activating HER3 in a neuregulin-independent fashion, thus elucidation of these mechanisms may reveal new strategies for treating patients with mCRC.

METHODS

Patient-derived primary liver endothelial cells (ECs) were used to interrogate EC-CRC crosstalk. We conducted proteomic analysis to identify EC-secreted factor(s) that triggers noncanonical HER3 activation in CRC and determined the subsequent effects on mCRC using diverse murine mCRC models. In vitro studies with genetic and pharmacological interventions were used to map the noncanonical HER3 pathway.

RESULTS

We demonstrated that EC-secreted leucine-rich alpha-2-glycoprotein 1 (LRG1) directly binds and activates HER3 and promotes CRC growth distinct from neuregulin, the canonical HER3 ligand. Blocking host-derived LRG1 by gene knockout or a neutralizing antibody impaired mCRC outgrowth in the liver and prolonged mouse survival. We identified protein synthesis activated by the PI3K-PDK1-RSK-eIF4B axis as the biologically relevant signaling cascade downstream of the LRG1-HER3 interaction, which was not blocked by conventional HER3-specific antibodies that failed in prior clinical trials.

CONCLUSIONS

LRG1 is a novel HER3 ligand and mediates liver-mCRC crosstalk. The LRG1-HER3 signaling axis is distinct from canonical HER3 signaling and represents a new therapeutic opportunity to treat patients with mCRC, and potentially other types of liver metastases.

Gut commensal Alistipes as a potential pathogenic factor in colorectal cancer

Although previous research has shown that inflammation is associated with development of colorectal cancer (CRC), questions remain about whether inflammatory factor-secreting bacteria play a crucial role in CRC development. The potential role of gut microbiota in secreting inflammatory factors involved in the carcinogenesis of CRC among Chinese patients was explored in this study. 16S rRNA sequencing was utilized to evaluate the distinct microbial characteristics between patients with CRC and colorectal adenoma. The serum levels of TNF-α, IL-6 and IL-10 were measured using Enzyme-linked immunosorbent assay (ELISA), while the expression of LRG1 and TGF-β1 in tissues was evaluated by immunohistochemistry. The correlation between gut microbiota and inflammatory factor signaling was analyzed. Compared with the adenoma group, CRC patients exhibit distinct pathologies. Moreover, elevated levels of CEA, erythrocytes and haemoglobin in the blood of CRC patients were found. In addition, CRC patients have significantly higher levels of TNF-α, IL-6, IL-10, LRG1 and TGF-β1. Spearman correlation analysis revealed that LRG1 was positively related to IL-6 and TNF-α, respectively. The correlation analysis results of TGF-β1 were consistent with the above. The abundance of Blautia and Streptococcus was lower in CRC patients, while the relative abundance of Alistipes, Peptostreptococcus and Porphyromonas was significantly elevated. Moreover, positive correlations between Alistipes and inflammatory factor signaling were also found. Our results suggest that gut commensal Alistipes is a key bacterium with pro-inflammatory properties in the CRC carcinogenesis. TNF-α and IL-6 associated with Alistipes might activate LRG1/TGF-β1 signaling which contributed to the carcinogenesis of CRC.

Association Between Plasma LRG1 and Lower Cognitive Function in Asians With Type 2 Diabetes Mellitus

CONTEXT

Leucine-rich α-2-glycoprotein 1 (LRG1) has been implicated in the pathogenesis of diabetic complications, but its association with cognitive function remains unclear.

OBJECTIVE

Our primary objective is to investigate the longitudinal association between LRG1 and cognitive function in patients with type 2 diabetes mellitus (T2DM). Secondarily, we determine the causal relationship using Mendelian randomization (MR) and the role of arterial stiffness as a potential mediator.

METHODS

T2DM patients (n = 1039; age = 64.1 ± 6.4 years) were followed-up for 5.3 ± 1.2 years. Plasma LRG1 was measured at baseline using enzyme-linked immunosorbent assay. Baseline and follow-up cognitive function was assessed using Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). One-sample MR was performed with rs4806985 as plasma LRG1-associated single-nucleotide polymorphism. Mediation analysis was performed to examine if pulse wave velocity (PWV), an arterial stiffness index, mediated the association between plasma LRG1 and follow-up cognitive function.

RESULTS

Elevated baseline natural log (Ln)-transformed LRG1 was inversely associated with baseline and follow-up RBANS total score with adjusted coefficients -1.38 (95% CI -2.55 to -.21; P = .021) and -1.38 (95% CI -2.70 to -.07; P = .039), respectively. Genetically predicted higher levels of plasma LRG1 was associated with lower follow-up RBANS total score with coefficient -7.44 (95% CI -14.14 to -.74; P = .030) per unit increase in LnLRG1. Higher PWV accounted for 27.7% of the association between LnLRG1 and follow-up RBANS total score.

CONCLUSION

Baseline plasma LRG1 was associated with lower cognitive function at follow-up in patients with T2DM, mediated by PWV. MR analysis provided evidence of an association between genetically influenced plasma LRG1 and lower cognitive function at follow-up.

The disruptive role of LRG1 on the vasculature and perivascular microenvironment

The establishment of new blood vessels, and their subsequent stabilization, is a critical process that facilitates tissue growth and organ development. Once established, vessels need to diversify to meet the specific needs of the local tissue and to maintain homeostasis. These processes are tightly regulated and fundamental to normal vessel and tissue function. The mechanisms that orchestrate angiogenesis and vessel maturation have been widely studied, with signaling crosstalk between endothelium and perivascular cells being identified as an essential component. In disease, however, new vessels develop abnormally, and existing vessels lose their specialization and function, which invariably contributes to disease progression. Despite considerable research into the vasculopathic mechanisms in disease, our knowledge remains incomplete. Accordingly, the identification of angiocrine and angiopathic molecules secreted by cells within the vascular microenvironment, and their effect on vessel behaviour, remains a major research objective. Over the last decade the secreted glycoprotein leucine-rich α-2 glycoprotein 1 (LRG1), has emerged as a significant vasculopathic molecule, stimulating defective angiogenesis, and destabilizing the existing vasculature mainly, but not uniquely, by altering both canonical and non-canonical TGF-β signaling in a highly cell and context dependent manner. Whilst LRG1 does not possess any overt homeostatic role in vessel development and maintenance, growing evidence provides a compelling case for LRG1 playing a pleiotropic role in disrupting the vasculature in many disease settings. Thus, LRG1 has now been reported to damage vessels in various disorders including cancer, diabetes, chronic kidney disease, ocular disease, and lung disease and the signaling processes that drive this dysfunction are being defined. Moreover, therapeutic targeting of LRG1 has been widely proposed to re-establish a quiescent endothelium and normalized vasculature. In this review, we consider the current status of our understanding of the role of LRG1 in vascular pathology, and its potential as a therapeutic target.

Type I gamma phosphatidylinositol phosphate 5-kinase i5 controls cell sensitivity to interferon

The interferon signaling pathway is critical for host defense by serving diverse functions in both innate and adaptive immune responses. Here, we show that type I gamma phosphatidylinositol phosphate 5-kinase i5 (PIPKIγi5), an enzyme that synthesizes phosphatidylinositol-4,5-bisphosphate (PI4,5P2), controls the sensitivity to interferon in both human and mouse cells. PIPKIγi5 directly binds to the interferon-gamma (IFN-γ) downstream effector signal transducer and activator of transcription 1 (STAT1), which suppresses the STAT1 dimerization, IFN-γ-induced STAT1 nuclear translocation, and transcription of IFN-γ-responsive genes. Depletion of PIPKIγi5 significantly enhances IFN-γ signaling and strengthens an antiviral response. In addition, PIPKIγi5-synthesized PI4,5P2 can bind to STAT1 and promote the PIPKIγi5-STAT1 interaction. Similar to its interaction with STAT1, PIPKIγi5 is capable of interacting with other members of the STAT family, including STAT2 and STAT3, thereby suppressing the expression of genes mediated by these transcription factors. These findings identify the function of PIPKIγi5 in immune regulation.

Fructose overconsumption accelerates renal dysfunction with aberrant glomerular endothelial-mesangial cell interactions in db/db mice

For the advancement of DKD treatment, identifying unrecognized residual risk factors is essential. We explored the impact of obesity diversity derived from different carbohydrate qualities, with an emphasis on the increasing trend of excessive fructose consumption and its effect on DKD progression. In this study, we utilized db/db mice to establish a novel diabetic model characterized by fructose overconsumption, aiming to uncover the underlying mechanisms of renal damage. Compared to the control diet group, the fructose-fed db/db mice exhibited more pronounced obesity yet demonstrated milder glucose intolerance. Plasma cystatin C levels were elevated in the fructose model compared to the control, and this elevation was accompanied by enhanced glomerular sclerosis, even though albuminuria levels and tubular lesions were comparable. Single-cell RNA sequencing of the whole kidney highlighted an increase in Lrg1 in glomerular endothelial cells (GECs) in the fructose model, which appeared to drive mesangial fibrosis through enhanced TGF-β1 signaling. Our findings suggest that excessive fructose intake exacerbates diabetic kidney disease progression, mediated by aberrant Lrg1-driven crosstalk between GECs and mesangial cells.

Mechanisms of blood-retinal barrier disruption related to intraocular inflammation and malignancy

Blood-retinal barrier (BRB) disruption is a common accompaniment of intermediate, posterior and panuveitis causing leakage into the retina and macular oedema resulting in vision loss. It is much less common in anterior uveitis or in patients with intraocular lymphoma who may have marked signs of intraocular inflammation. New drugs used for chemotherapy (cytarabine, immune checkpoint inhibitors, BRAF inhibitors, EGFR inhibitors, bispecific anti-EGFR inhibitors, MET receptor inhibitors and Bruton tyrosine kinase inhibitors) can also cause different types of uveitis and BRB disruption. As malignant disease itself can cause uveitis, particularly from breast, lung and gastrointestinal tract cancers, it can be clinically difficult to sort out the cause of BRB disruption. Immunosuppression due to malignant disease and/or chemotherapy can lead to infection which can also cause BRB disruption and intraocular infection. In this paper we address the pathophysiology of BRB disruption related to intraocular inflammation and malignancy, methods for estimating the extent and effect of the disruption and examine why some types of intraocular inflammation and malignancy cause BRB disruption and others do not. Understanding this may help sort and manage these patients, as well as devise future therapeutic approaches.

Prognostic potency of plasma LRG1 measurement at multiple time points in acute ischemic stroke patients

Objective: This study aimed to investigate the prognostic potency of LRG1 in acute ischemic stroke (AIS) patients. Methods: Plasma LRG1 levels were detected at admission and on days 3, 7 and 30 in 150 AIS patients. Results: LRG1 positively correlated with total cholesterol (p = 0.016), triglycerides (p = 0.046), C-reactive protein (p < 0.001), TNF-α (p = 0.001) and IL-6 (p = 0.004). After admission, LRG1 showed a decreasing trend (p < 0.001). Interestingly, LRG1 levels at admission (p = 0.014), day 3 (p = 0.027), day 7 (p = 0.008) and day 30 (p = 0.002) were higher in patients with modified Rankin scale score ≥2 versus those with scores <2. The LRG1 levels at day 7 (p = 0.032) and day 30 (p = 0.023) were higher in patients with recurrence versus no recurrence. Conclusion: LRG1 correlates with blood lipids, inflammation and short-term prognosis of AIS.

WNT7A promotes tumorigenesis of head and neck squamous cell carcinoma via activating FZD7/JAK1/STAT3 signaling

Wnt signaling are critical pathway involved in organ development, tumorigenesis, and cancer progression. WNT7A, a member of the Wnt family, remains poorly understood in terms of its role and the underlying molecular mechanisms it entails in head and neck squamous cell carcinoma (HNSCC). According to the Cancer Genome Atlas (TCGA), transcriptome sequencing data of HNSCC, the expression level of WNT7A in tumors was found to be higher than in adjacent normal tissues, which was validated using Real-time RT-PCR and immunohistochemistry. Unexpectedly, overexpression of WNT7A did not activate the canonical Wnt-β-catenin pathway in HNSCC. Instead, our findings suggested that WNT7A potentially activated the FZD7/JAK1/STAT3 signaling pathway, leading to enhanced cell proliferation, self-renewal, and resistance to apoptosis. Furthermore, in a patient-derived xenograft (PDX) tumor model, high expression of WNT7A and phosphorylated STAT3 was observed, which positively correlated with tumor progression. These findings underscore the significance of WNT7A in HNSCC progression and propose the targeting of key molecules within the FZD7/JAK1/STAT3 pathway as a promising strategy for precise treatment of HNSCC.

Application of LRG mechanism in normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is a prevalent type of hydrocephalus, including secondary normal pressure hydrocephalus (SNPH) and idiopathic normal pressure hydrocephalus (INPH). However, its clinical diagnosis and pathological mechanism are still unclear. Leucine-rich α-2 glycoprotein (LRG) is involved in various human diseases, including cancer, diabetes, cardiovascular disease, and nervous system diseases. Now the physiological mechanism of LRG is still being explored. According to the current research results on LRG, we found that the agency of LRG has much to do with the known pathological process of NPH. This review focuses on analyzing the LRG signaling pathways and the pathological mechanism of NPH. According to the collected literature evidence, we speculated that LRG probably be involved in the pathological process of NPH. Finally, based on the mechanism of LRG and NPH, we also summarized the evidence of molecular targeted therapies for future research and clinical application.

LRG1 Associates with Iron Deficiency Anemia Markers in Adolescents

Leucine-rich α-2 glycoprotein1 (LRG1) has been shown to be associated with several health conditions; however, its association with iron deficiency anemia, especially in children, has not been previously explored. In this study, we investigated the association between LRG1 and several iron deficiency anemia markers, including hemoglobin (Hb), albumin, red cell distribution width (RDW), iron, ferritin, and Hb transferrin saturation. A total of 431 participants were included in this analysis aged between 11 and 14 years. Higher LRG1 levels were observed in children diagnosed with anemia [31.1 (24.6, 43.2) µg/mL] compared to non-anemic children [29.2 (22.7-35.95) µg/mL]. Statistically significant differences of LRG1 level across the three groups (tertiles) of Hb, iron, transferrin saturation, albumin, RDW, ferritin, and WBC were observed. Strong negative correlations were observed between LRG1 and Hb (Spearman's rho = -0.11, p = 0.021), albumin (Spearman's rho = -0.24, p < 0.001), iron (Spearman's rho = -0.25, p < 0.001), and Hb transferrin saturation (Spearman's rho = -0.24, p < 0.001), whereas circulating LRG1 levels were positively associated with RDW (Spearman's rho = 0.21, p < 0.001). In conclusion, our findings demonstrate for the first time the strong association between iron deficiency anemia markers and LRG1 in otherwise healthy school-aged children. However, further studies are needed to corroborate those results and to look for similar associations in other population subgroups.

Increased LRG1 Levels in Overweight and Obese Adolescents and Its Association with Obesity Markers, Including Leptin, Chemerin, and High Sensitivity C-Reactive Protein

Leucine-rich α-2 glycoprotein1 (LRG1) is a member of the leucine-rich repeat (LRR) family that is implicated in multiple diseases, including cancer, aging, and heart failure, as well as diabetes and obesity. LRG1 plays a key role in diet-induced hepatosteatosis and insulin resistance by mediating the crosstalk between adipocytes and hepatocytes. LRG1 also promotes hepatosteatosis by upregulating de novo lipogenesis in the liver and suppressing fatty acid β-oxidation. In this study, we investigated the association of LRG1 with obesity markers, including leptin and other adipokines in adolescents (11−14 years; n = 425). BMI-for-age classification based on WHO growth charts was used to define obesity. Plasma LRG1 was measured by ELISA, while other markers were measured by multiplexing assay. Median (IQR) of LRG1 levels was higher in obese (30 (25, 38) µg/mL) and overweight (30 (24, 39) µg/mL) adolescents, compared to normal-weight participants (27 (22, 35) µg/mL). The highest tertile of LRG1 had an OR [95% CI] of 2.55 [1.44, 4.53] for obesity. LRG1 was positively correlated to plasma levels of high sensitivity c-reactive protein (HsCRP) (ρ = 0.2), leptin (ρ = 0.2), and chemerin (ρ = 0.24) with p < 0.001. Additionally, it was positively associated with plasma level of IL6 (ρ = 0.17) and IL10 (ρ = 0.14) but not TNF-α. In conclusion, LRG1 levels are increased in obese adolescents and are associated with increased levels of adipogenic markers. These results suggest the usefulness of LRG1 as an early biomarker for obesity and its related pathologies in adolescents.

Association between Higher Circulating Leucine-Rich α-2 Glycoprotein 1 Concentrations and Specific Plasma Ceramides in Postmenopausal Women with Type 2 Diabetes

Background: Although ceramides are involved in the pathophysiology of cardiovascular disease and other inflammation-associated disorders, there is a paucity of data on the association between plasma ceramides and inflammatory biomarkers in type 2 diabetes mellitus (T2DM). Therefore, we explored whether there was an association between plasma leucine-rich α-2 glycoprotein 1 (LRG1) concentrations (i.e., a novel proinflammatory signaling molecule) and specific plasma ceramides in postmenopausal women with T2DM. Methods: We measured six previously identified plasma ceramides, which have been associated with increased cardiovascular risk [plasma Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/20:0), Cer(d18:1/22:0), Cer(d18:1/24:0) and Cer(d18:1/24:1)], amongst 99 Caucasian postmenopausal women with non-insulin-treated T2DM (mean age 72 ± 8 years, mean hemoglobin A1c 6.9 ± 0.7%), who consecutively attended our diabetes outpatient service during a 3-month period. Plasma ceramide and LRG1 concentrations were measured with a targeted liquid chromatography-tandem mass spectrometry assay and a Milliplex® MAP human cardiovascular disease magnetic bead kit, respectively. Results: In linear regression analyses, higher plasma LRG1 levels (1st tertile vs. 2nd and 3rd tertiles combined) were associated with higher levels of plasma Cer(d18:1/16:0) (standardized β coefficient: 0.289, p = 0.004), Cer(d18:1/18:0) (standardized β coefficient: 0.307, p = 0.002), Cer(d18:1/20:0) (standardized β coefficient: 0.261, p = 0.009) or Cer(d18:1/24:1) (standardized β coefficient: 0.343, p < 0.001). These associations remained significant even after adjusting for age, body mass index, systolic blood pressure, total cholesterol level, hemoglobin A1c, insulin resistance and statin use. Conclusions: The results of our pilot exploratory study suggest that higher plasma LRG1 concentration was associated with higher levels of specific high-risk plasma ceramide molecules in elderly postmenopausal women with metabolically well-controlled T2DM, even after adjusting for known cardiovascular risk factors and other potential confounding variables.