Kallistatin inhibits vascular inflammation by antagonizing tumor necrosis factor-alpha-induced nuclear factor kappaB activation

Practicability of Serum Kallistatin Levels as a Biomarker in the Diagnosis of Tubo-Ovarian Abscess

Objective: This study investigates the practicability of serum kallistatin as a biomarker in the diagnosis of tubo-ovarian abscess (TOA) because C-reactive protein (CRP) is insufficiently specific for diagnosis. Methods: Thirty patients (control group) who presented for elective gynecological surgeries and 30 who were hospitalized due to TOA (study group) at the Antalya Training and Research Hospital Gynecology Clinic, Türkiye, between January 1 and December 31, 2022, were included in the study. Blood samples were collected for the calculation of complete blood count, biochemistry, CRP, and serum kallistatin values, and the results were recorded in a database. Results: Although no significant differences were observed between the control and study groups in terms of age or body mass index, significant differences were observed in terms of marital status, number of pregnancies, parity number, intrauterine device history, and previous surgical history (p > 0.05). Serum hemoglobin levels (12.61 ± 1.30 vs. 11.47 ± 1.77; p = 0.008), white blood cell (7.9 [6.15 ± 9.7] vs. 17.0 [11.6-19.6]; p < 0.001), neutrophil (4.6 [3.6-6.12] vs. 13.6 [9.25-16.1]; p < 0.001), lymphocyte (2.51 ± 0.71 vs. 2.33 ± 0.69; p = 0.307), and platelet counts (285.63 ± 78.0 vs. 407.03 ± 131.96; p < 0.001), neutrophil-lymphocyte ratio (2.11 ± 0.93 vs. 6.18 ± 2.20; p < 0.001), neutrophil-lymphocyte ratio (123.16 ± 52.63 vs. 184.39 ± 63.90; p < 0.001), hs-CRP (1.20 [5.55-1.92] vs. 240 [138.25-291.0]; p < 0.001), kallistatin (7.18 ± 3.15 vs. 3.83 ± 3.69; p = 0.006), and urine leukocyte values (1 [0.75-3] vs. 3 [1-6.5]; p = 0.038) also differed significantly between the control and study groups. Conclusion: The study findings show that serum kallistatin levels can be used as a biomarker in the diagnosis of TOA. Further studies involving more participants are now needed to test the accuracy of our results.

MicroRNA-21 (miR-21) in breast cancer: From apoptosis dysregulation to therapeutic opportunities

Breast cancer, a pervasive and complex disease, continues to pose significant challenges in the field of oncology. Its heterogeneous nature and diverse molecular profiles necessitate a nuanced understanding of the underlying mechanisms driving tumorigenesis and progression. MicroRNA-21 (miR-21) has emerged as a crucial player in breast cancer development and progression by modulating apoptosis, a programmed cell death mechanism that eliminates aberrant cells. MiR-21 overexpression is a hallmark of breast cancer, and it is associated with poor prognosis and resistance to conventional therapies. This miRNA exerts its oncogenic effects by targeting various pro-apoptotic genes, including Fas ligand (FasL), programmed cell death protein 4 (PDCD4), and phosphatase and tensin homolog (PTEN). By suppressing these genes, miR-21 promotes breast cancer cell survival, proliferation, invasion, and metastasis. The identification of miR-21 as a critical regulator of apoptosis in breast cancer has opened new avenues for therapeutic intervention. This review investigates the intricate mechanisms through which miR-21 influences apoptosis, offering insights into the molecular pathways and signaling cascades involved. The dysregulation of apoptosis is a hallmark of cancer, and understanding the role of miR-21 in this context holds immense therapeutic potential. Additionally, the review highlights the clinical significance of miR-21 as a diagnostic and prognostic biomarker in breast cancer, underscoring its potential as a therapeutic target.

Associations between Serum Kallistatin Levels and Markers of Glucose Homeostasis, Inflammation, and Lipoprotein Metabolism in Patients with Type 2 Diabetes and Nondiabetic Obesity

Kallistatin is an endogenous serine proteinase inhibitor with various functions, including antioxidative, anti-inflammatory, and anti-atherosclerotic properties. To date, associations between kallistatin and lipoprotein subfractions are poorly investigated. In this study, we enrolled 62 obese patients with type 2 diabetes (T2D), 106 nondiabetic obese (NDO) subjects matched in gender, age, and body mass index, as well as 49 gender- and age-matched healthy, normal-weight controls. Serum kallistatin levels were measured with ELISA, and lipoprotein subfractions were analyzed using Lipoprint® (Quantimetrix Corp., Redondo Beach, CA, USA) gel electrophoresis. Kallistatin concentrations were significantly higher in T2D patients compared to NDO and control groups. We found significant positive correlations between very-low-density lipoprotein (VLDL), small high-density lipoprotein (HDL) subfractions, glucose, hemoglobin A1c (HbA1c), betatrophin, and kallistatin, while negative correlations were detected between mean low-density lipoprotein (LDL) size, large and intermediate HDL subfractions, and kallistatin in the whole study population. The best predictor of kallistatin was HbA1c in T2D patients, high-sensitivity C-reactive protein (hsCRP) and betatrophin in NDO patients, and hsCRP in controls. Our results indicate that kallistatin expression might be induced by persistent hyperglycemia in T2D, while in nondiabetic subjects, its production might be associated with systemic inflammation. The correlation of kallistatin with lipid subfractions may suggest its putative role in atherogenesis.

Protective role of kallistatin in oxygen-glucose deprivation and reoxygenation in human umbilical vein endothelial cells

OBJECTIVE

Ischemia-reperfusion (IR) injury is implicated in various clinical diseases. Kallistatin attenuates oxidative stress, and its deficiency has been associated with poor neurological outcomes after cardiac arrest. The present study investigated the antioxidant mechanism through which kallistatin prevents IR injury.

METHODS

Human umbilical vein endothelial cells (HUVECs) were transfected with small interfering RNA (siRNA) targeting the human kallistatin gene (SERPINA4). Following SERPINA4 knockdown, the level of kallistatin expression was measured. To induce IR injury, HUVECs were exposed to 24 h of oxygen-glucose deprivation and reoxygenation (OGD/R). To evaluate the effect of SERPINA4 knockdown on OGD/R, cell viability and the concentration of kallistatin, endothelial nitric oxide synthase (eNOS) and total NO were measured.

RESULTS

SERPINA4 siRNA transfection suppressed the expression of kallistatin in HUVECs. Exposure to OGD/R reduced cell viability, and this effect was more pronounced in SERPINA4 knockdown cells compared with controls. SERPINA4 knockdown significantly reduced kallistatin concentration regardless of OGD/R, with a more pronounced effect observed without OGD/R. Furthermore, SERPINA4 knockdown significantly decreased eNOS concentrations induced by OGD/R (P<0.01) but did not significantly affect the change in total NO concentration (P=0.728).

CONCLUSION

The knockdown of SERPINA4 resulted in increased vulnerability of HUVECs to OGD/R and significantly affected the change in eNOS level induced by OGD/R. These findings suggest that the protective effect of kallistatin against IR injury may contribute to its eNOS-promoting effect.

Kallistatin as an inhibitory protein against colorectal cancer cells through binding to LRP6

Kallistatin (KL) is a member of the serine proteinase inhibitor (serpin) family regulating oxidative stress, vascular relaxation, inflammation, angiogenesis, cell proliferation, and invasion. The heparin-binding site of Kallistatin has an important role in the interaction with LRP6 leading to the blockade of the Wnt signaling pathway. In this study, we aimed to explore the structural basis of the Kallistatin-LRP6E1E4 complex using in silico approaches and evaluating the anti-proliferative, apoptotic, and cell cycle arrest activities of Kallistatin in colon cancer lines. The molecular docking showed Kallistatin could bind to the LRP6E3E4 much stronger than LRP6E1E2. The Kallistatin-LRP6E1E2 and Kallistatin-LRP6E3E4 complexes were stable during Molecular Dynamics (MD) simulation. The Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) showed that the Kallistatin-LRP6E3E4 has a higher binding affinity compared to Kallistatin-LRP6E1E2. Kallistatin induced higher cytotoxicity and apoptosis in HCT116 compared to the SW480 cell line. This protein-induced cell-cycle arrest in both cell lines at the G1 phase. The B-catenin, cyclin D1, and c-Myc expression levels were decreased in response to treatment with Kallistatin in both cell lines while the LRP6 expression level was decreased in the HCT116 cell line. Kallistatin has a greater effect on the HCT116 cell line compared to the SW480 cell line. Kallistatin can be used as a cytotoxic and apoptotic-inducing agent in colorectal cancer cell lines.

Kallistatin attenuates inflammatory response in rheumatoid arthritis via the NF-κB signaling pathway

Cartilage degeneration and inflammation are important features of rheumatoid arthritis (RA). Chondrocyte inflammation and apoptosis have been increasingly demonstrated to be related to cartilage decomposition. In this study, we analyzed the protective role of kallistatin against RA and its associated mechanisms. We obtained in vitro and in vivo RA models using IL-1β and heat-inactivated Mycobacterium tuberculosis, respectively. Our results showed that kallistatin mitigated IL-1β-mediated chondrocyte apoptosis and inhibited the synthesis of ECM-degrading generation, like matrix metalloproteinase (MMP)-3/13 and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4/5, in IL-1β-mediated chondrocytes. Furthermore, kallistatin markedly suppressed IL-1β-mediated inflammation while decreasing the levels of inflammatory factors and mediators via the NF-κB pathway. Daily administration of kallistatin reduced the expression levels of PGE2, TNF-α, IL-1β, and IL-6. Histochemical analysis revealed that the kallistatin-treated rats exhibited reduced RA severity compared with control mice. In summary, kallistatin suppressed IL-1β-mediated inflammation in chondrocytes via the NF-κB pathway. Administration of kallistatin remarkably inhibited RA development, accompanied by reduced inflammation and apoptosis. Therefore, kallistatin administration can be used as a candidate therapeutic strategy for RA.

Pentosan Polysulfate Affords Pleotropic Protection to Multiple Cells and Tissues

Pentosan polysulfate (PPS), a small semi-synthetic highly sulfated heparan sulfate (HS)-like molecule, shares many of the interactive properties of HS. The aim of this review was to outline the potential of PPS as an interventional therapeutic protective agent in physiological processes affecting pathological tissues. PPS is a multifunctional molecule with diverse therapeutic actions against many disease processes. PPS has been used for decades in the treatment of interstitial cystitis and painful bowel disease, it has tissue-protective properties as a protease inhibitor in cartilage, tendon and IVD, and it has been used as a cell-directive component in bioscaffolds in tissue engineering applications. PPS regulates complement activation, coagulation, fibrinolysis and thrombocytopenia, and it promotes the synthesis of hyaluronan. Nerve growth factor production in osteocytes is inhibited by PPS, reducing bone pain in osteoarthritis and rheumatoid arthritis (OA/RA). PPS also removes fatty compounds from lipid-engorged subchondral blood vessels in OA/RA cartilage, reducing joint pain. PPS regulates cytokine and inflammatory mediator production and is also an anti-tumor agent that promotes the proliferation and differentiation of mesenchymal stem cells and the development of progenitor cell lineages that have proven to be useful in strategies designed to effect repair of the degenerate intervertebral disc (IVD) and OA cartilage. PPS stimulates proteoglycan synthesis by chondrocytes in the presence or absence of interleukin (IL)-1, and stimulates hyaluronan production by synoviocytes. PPS is thus a multifunctional tissue-protective molecule of potential therapeutic application for a diverse range of disease processes.

Diagnostic circulating biomarkers to detect vision-threatening diabetic retinopathy: Potential screening tool of the future?

With the increasing prevalence of diabetes in developing and developed countries, the socio-economic burden of diabetic retinopathy (DR), the leading complication of diabetes, is growing. Diabetic retinopathy (DR) is currently one of the leading causes of blindness in working-age adults worldwide. Robust methodologies exist to detect and monitor DR; however, these rely on specialist imaging techniques and qualified practitioners. This makes detecting and monitoring DR expensive and time-consuming, which is particularly problematic in developing countries where many patients will be remote and have little contact with specialist medical centres. Diabetic retinopathy (DR) is largely asymptomatic until late in the pathology. Therefore, early identification and stratification of vision-threatening DR (VTDR) is highly desirable and will ameliorate the global impact of this disease. A simple, reliable and more cost-effective test would greatly assist in decreasing the burden of DR around the world. Here, we evaluate and review data on circulating protein biomarkers, which have been verified in the context of DR. We also discuss the challenges and developments necessary to translate these promising data into clinically useful assays, to detect VTDR, and their potential integration into simple point-of-care testing devices.

Kallistatin in follicular fluid of women with endometriosis and its correlation with IVF outcome

BACKGROUND

Endometriosis (EM) affects 10% women of reproductive age and alters fertility. Its management is still debated notably the timing of surgery and ART in infertility. Kallistatin (KS) is an endogenous protein that regulates differential signaling pathways and biological functions. However, the function and the underlying molecular mechanism in EM and its correlation with in vitro fertilization (IVF) outcome have not been determined. The purpose of this study was to evaluate KS concentrations in follicular fluid (FF) of women with EM and controls women without EM who underwent IVF with embryo transfer (IVF-ET).

METHODS

FF KS concentrations from 40 patients with EM and 40 non-EM patients were measured by ELISA.

RESULTS

Compared with the non-EM patients, patients with EM had lower KS levels in FF (281.67 ± 104.60 vs. 490.70 ± 216.33 pg/ml). The rates of fertilization (61.64 ± 22.42 vs. 71.00 ± 24.39%), available embryo (45.96 ± 19.83 vs. 50.61 ± 26.26%), and top-quality embryo (12.71 ± 21.01 vs. 16.04 ± 16.87%) were significantly lower in the EM group than in the control group. The KS concentrations in the FF of women who conceived consequent to the treatment were significantly higher than those from women who did not in the combined EM and control groups.

CONCLUSIONS

These results indicate that the KS concentration in FF could be used as a predictor for IVF-ET outcomes. This may contribute to the pathologic mechanism responsible for the poor outcome of IVF in patients with EM.

Overexpressing Kallistatin Aggravates Experimental Autoimmune Uveitis Through Promoting Th17 Differentiation

Kallistatin or kallikrein-binding protein (KBP) has been reported to regulate angiogenesis, inflammation and tumor progression. Autoimmune uveitis is a common, sight-threatening inflammatory intraocular disease. However, the roles of kallistatin in autoimmunity and autoreactive T cells are poorly investigated. Compared to non-uveitis controls, we found that plasma levels of kallistatin were significantly upregulated in patients with Vogt-Koyanagi-Harada (VKH) disease, one of the non-infectious uveitis. Using an experimental autoimmune uveitis (EAU) model induced by human interphotoreceptor retinoid-binding protein peptide 651-670 (hIRBP_651-670), we examined the effects of kallistatin on the pathogenesis of autoimmune diseases. Compared to wild type (WT) mice, kallistatin transgenic (KS) mice developed severe uveitis with dominant Th17 infiltrates in the eye. In addition, the proliferative antigen-specific T cells isolated from KS EAU mice produced increased levels of IL-17A, but not IFN-γ or IL-10 cytokines. Moreover, splenic CD4⁺ T cells from naïve KS mice expressed higher levels of Il17a mRNA compared to WT naïve mice. Under Th17 polarization conditions, KS mice exhibited enhanced differentiation of naïve CD4⁺ T cells into Th17 cells compared to WT controls. Together, our results indicate that kallistatin promotes Th17 differentiation and is a key regulator of aggravating autoinflammation in EAU. Targeting kallistatin might be a potential to treat autoimmune disease.

Kallistatin limits abdominal aortic aneurysm by attenuating generation of reactive oxygen species and apoptosis

Inflammation, vascular smooth muscle cell apoptosis and oxidative stress are believed to play important roles in abdominal aortic aneurysm (AAA) pathogenesis. Human kallistatin (KAL; gene SERPINA4) is a serine proteinase inhibitor previously shown to inhibit inflammation, apoptosis and oxidative stress. The aim of this study was to investigate the role of KAL in AAA through studies in experimental mouse models and patients. Serum KAL concentration was negatively associated with the diagnosis and growth of human AAA. Transgenic overexpression of the human KAL gene (KS-Tg) or administration of recombinant human KAL (rhKAL) inhibited AAA in the calcium phosphate (CaPO₄) and subcutaneous angiotensin II (AngII) infusion mouse models. Upregulation of KAL in both models resulted in reduction in the severity of aortic elastin degradation, reduced markers of oxidative stress and less vascular smooth muscle apoptosis within the aorta. Administration of rhKAL to vascular smooth muscle cells incubated in the presence of AngII or in human AAA thrombus-conditioned media reduced apoptosis and downregulated markers of oxidative stress. These effects of KAL were associated with upregulation of Sirtuin 1 activity within the aortas of both KS-Tg mice and rodents receiving rhKAL. These results suggest KAL-Sirtuin 1 signalling limits aortic wall remodelling and aneurysm development through reductions in oxidative stress and vascular smooth muscle cell apoptosis. Upregulating KAL may be a novel therapeutic strategy for AAA.

Genetic Susceptibility to Acute Kidney Injury

Acute kidney injury (AKI) is a widely held concern related to a substantial burden of morbidity, mortality and expenditure in the healthcare system. AKI is not a simple illness but a complex conglomeration of syndromes that often occurs as part of other syndromes in its wide clinical spectrum of the disease. Genetic factors have been suggested as potentially responsible for its susceptibility and severity. As there is no current cure nor an effective treatment other than generally accepted supportive measures and renal replacement therapy, updated knowledge of the genetic implications may serve as a strategic tactic to counteract its dire consequences. Further understanding of the genetics that predispose AKI may shed light on novel approaches for the prevention and treatment of this condition. This review attempts to address the role of key genes in the appearance and development of AKI, providing not only a comprehensive update of the intertwined process involved but also identifying specific markers that could serve as precise targets for further AKI therapies.

Protective role of kallistatin in renal fibrosis via modulation of Wnt/β-catenin signaling

Kallistatin is a multiple functional serine protease inhibitor that protects against vascular injury, organ damage and tumor progression. Kallistatin treatment reduces inflammation and fibrosis in the progression of chronic kidney disease (CKD), but the molecular mechanisms underlying this protective process and whether kallistatin plays an endogenous role are incompletely understood. In the present study, we observed that renal kallistatin levels were significantly lower in patients with CKD. It was also positively correlated with estimated glomerular filtration rate (eGFR) and negatively correlated with serum creatinine level. Unilateral ureteral obstruction (UUO) in animals also led to down-regulation of kallistatin protein in the kidney, and depletion of endogenous kallistatin by antibody injection resulted in aggravated renal fibrosis, which was accompanied by enhanced Wnt/β-catenin activation. Conversely, overexpression of kallistatin attenuated renal inflammation, interstitial fibroblast activation and tubular injury in UUO mice. The protective effect of kallistatin was due to the suppression of TGF-β and β-catenin signaling pathways and subsequent inhibition of epithelial-to-mesenchymal transition (EMT) in cultured tubular cells. In addition, kallistatin could inhibit TGF-β-mediated fibroblast activation via modulation of Wnt4/β-catenin signaling pathway. Therefore, endogenous kallistatin protects against renal fibrosis by modulating Wnt/β-catenin-mediated EMT and fibroblast activation. Down-regulation of kallistatin in the progression of renal fibrosis underlies its potential as a valuable clinical biomarker and therapeutic target in CKD.

Kallistatin Attenuates Experimental Autoimmune Uveitis by Inhibiting Activation of T Cells

Experimental autoimmune uveoretinitis (EAU) is a mouse model of human autoimmune uveitis. EAU spontaneously resolves and is marked by ocular autoantigen-specific regulatory immunity in the spleen. Kallikrein binding protein (KBP) or kallistatin is a serine proteinase inhibitor that inhibits angiogenesis and inflammation, but its role in autoimmune uveitis has not been explored. We report that T cells activation is inhibited and EAU is attenuated in human KBP (HKBP) mice with no significant difference in the Treg population that we previously identified both before and after recovery from EAU. Moreover, following EAU immunization HKBP mice have potent ocular autoantigen specific regulatory immunity that is functionally suppressive.

Diabetes-induced upregulation of kallistatin levels exacerbates diabetic nephropathy via RAS activation

Kallistatin is an inhibitor of tissue kallikrein and also inhibits the Wnt pathway. Its role in diabetic nephropathy (DN) is uncertain. Here we reported that serum kallistatin levels were significantly increased in diabetic patients with DN compared to those in diabetic patients without DN and healthy controls, and positively correlated with urinary albumin excretion. In addition, renal kallistatin levels were significantly upregulated in mouse models of type 1 (Akita, OVE26) and type 2 diabetes (db/db). To unveil the effects of kallistatin on DN and its underlying mechanism, we crossed transgenic mice overexpressing kallistatin with OVE26 mice (KS‐tg/OVE). Kallistatin overexpression exacerbated albuminuria, renal fibrosis, inflammation, and oxidative stress in diabetes. Kallikrein activity was inhibited while the renin‐angiotensin system (RAS) upregulated in the kidney of KS‐tg/OVE mice compared to WT/OVE mice, suggesting a disturbed balance between the RAS and kallikrein‐kinin systems. As shown by immunostaining of endothelial makers, renal vascular densities were decreased accompanied by increased HIF‐1α and erythropoietin levels in the kidneys of KS‐tg/OVE mice. Taken together, high levels of kallistatin exacerbate DN at least partly by inducing RAS overactivation and hypoxia. The present study demonstrated a positive correlation between kallistatin levels and DN, suggesting a potential biomarker for prognosis of DN.

Kallistatin correlates with inflammation in abdominal aortic aneurysm and suppresses its formation in mice

Background

Kallistatin (KS), encoded by SERPINA4, was suggested to play a protective role in many cardiovascular diseases. However, its role in the pathogenesis of abdominal aortic aneurysm (AAA) remains unclear. The aim of this study was to examine the potential association of KS with AAA pathogenesis.

Methods

We examined KS (SERPINA4) expression in human AAA by PCR, immunohistochemistry, western blotting, and enzyme-linked immunosorbent assay (ELISA) and analyzed correlations between kallistain and clinical data. We then analyzed the effect of recombinant KS on AAA formation and the Wingless (Wnt) signaling pathway in a mouse AAA model developed by angiotensin II (AngII) infusion to apolipoprotein E-deficient (ApoE^-/-) mice.

Results

In AAA tissue samples, KS was significantly increased compared with samples from the control group (P<0.001, P<0.001, respectively). Clinically, decreased SERPINA4 expression in AAA tissue samples represented an increased rate of iliac artery aneurysm [odds ratio (OR): 0.017; P=0.040]. And decreased plasma KS level represented a high risk for rupture (OR: 0.837; P=0.034). KS inhibited AAA formation and blocked the Wnt signaling pathway in AngII-infused ApoE^-/- mice.

Conclusions

The present study demonstrates that aberrant changes in KS expression occur in AAA. KS plays an important anti-inflammatory role and showed important clinical correlations in AAA. Decreased KS (SERPINA4) level is a risk factor of AAA rupture. Our pre-clinical animal experiments indicate that treatment with recombination KS suppresses AngII-induced aortic aneurysm formation and might be a new target for the drug therapy of AAA.

Kallistatin inhibits tumour progression and platinum resistance in high-grade serous ovarian cancer

Ovarian cancer is the most lethal gynaecologic malignancy. Although there are various subtypes of ovarian cancer, high-grade serous ovarian cancer (HGSOC) accounts for 70% of ovarian cancer deaths. Chemoresistance is the primary reason for the unfavourable prognosis of HGSOC. Kallistatin (KAL), also known as SERPINA4, is part of the serpin family. Kallistatin has been discovered to exert multiple effects on angiogenesis, inflammation and tumour progression. However, the roles and clinical significance of kallistatin in HGSOC remain unclear. Here, we showed that kallistatin was significantly downregulated in HGSOC compared to normal fallopian tube (FT) tissues. Low expression of kallistatin was associated with unfavourable prognosis and platinum resistance in HGSOC. Overexpression of kallistatin significantly inhibited proliferation and metastasis, and enhanced platinum sensitivity and apoptosis in ovarian cancer cells. Collectively, these findings demonstrate that kallistatin serves as a prognostic predictor and provide a potential therapeutic target for HGSOC.

Protective Role of Endogenous Kallistatin in Vascular Injury and Senescence by Inhibiting Oxidative Stress and Inflammation

Kallistatin was identified in human plasma as a tissue kallikrein-binding protein and a serine proteinase inhibitor. Kallistatin exerts pleiotropic effects on angiogenesis, oxidative stress, inflammation, apoptosis, fibrosis, and tumor growth. Kallistatin levels are markedly reduced in patients with coronary artery disease, sepsis, diabetic retinopathy, inflammatory bowel disease, pneumonia, and cancer. Moreover, plasma kallistatin levels are positively associated with leukocyte telomere length in young African Americans, indicating the involvement of kallistatin in aging. In addition, kallistatin treatment promotes vascular repair by increasing the migration and function of endothelial progenitor cells (EPCs). Kallistatin via its heparin-binding site antagonizes TNF-α-induced senescence and superoxide formation, while kallistatin's active site is essential for inhibiting miR-34a synthesis, thus elevating sirtuin 1 (SIRT1)/eNOS synthesis in EPCs. Kallistatin inhibits oxidative stress-induced cellular senescence by upregulating Let-7g synthesis, leading to modulate Let-7g-mediated miR-34a-SIRT1-eNOS signaling pathway in human endothelial cells. Exogenous kallistatin administration attenuates vascular injury and senescence in association with increased SIRT1 and eNOS levels and reduced miR-34a synthesis and NADPH oxidase activity, as well as TNF-α and ICAM-1 expression in the aortas of streptozotocin- (STZ-) induced diabetic mice. Conversely, endothelial-specific depletion of kallistatin aggravates vascular senescence, oxidative stress, and inflammation, with further reduction of Let-7g, SIRT1, and eNOS and elevation of miR-34a in mouse lung endothelial cells. Furthermore, systemic depletion of kallistatin exacerbates aortic injury, senescence, NADPH oxidase activity, and inflammatory gene expression in STZ-induced diabetic mice. These findings indicate that endogenous kallistatin displays a novel role in protection against vascular injury and senescence by inhibiting oxidative stress and inflammation.

Kallistatin Inhibits Atherosclerotic Inflammation by Regulating Macrophage Polarization

Kallistatin (KS) has been recognized as a plasma protein with anti-inflammatory functions. Macrophages are the primary inflammatory cells in atherosclerotic plaques. However, it is unknown whether KS plays a role in macrophage development and the pathogenesis of atherosclerosis. This study investigated the role of KS in macrophage development, a key pathological process in atherosclerosis. An atherosclerosis model was established in ApoE^-/- mice via partial left carotid artery (PLCA) ligation. An adenovirus vector (Ad. HKS) containing the human KS gene was delivered via the tail vein before PLCA ligation. The mice were divided into two groups: the PLCA + Ad. HKS and PLCA + adenovirus vector (Ad. Null) groups and followed for 2 and 4 weeks. Human KS was expressed in the mice after KS gene delivery. In addition, KS significantly inhibited plaque formation and reduced inflammation in the plaques and liver 4 weeks after gene delivery. Moreover, KS gene delivery significantly increased the expression of interleukin-10 and Arginase 1, which are M2 macrophage markers, and reduced the expression of inducible nitric oxide synthase and monocyte chemotactic protein 1, which are M1 macrophage markers. Furthermore, in cultured RAW 264.7 macrophages, KS significantly stimulated M2 marker expression and differentiation and decreased M1 marker expression, as determined by flow cytometry and real-time polymerase chain reaction. These effects were blocked by Krüppel-like factor 4 small-interfering RNA oligonucleotides. These findings demonstrate that KS inhibits atherosclerotic plaque formation and regulates M1/M2 macrophage polarization via Krüppel-like factor 4 activation.

Reduced Plasma Kallistatin Is Associated With the Severity of Coronary Artery Disease, and Kallistatin Treatment Attenuates Atherosclerotic Plaque Formation in Mice

Background Kallistatin exerts beneficial effects on organ injury by inhibiting oxidative stress and inflammation. However, the role of kallistatin in atherosclerosis is largely unknown. Here, we investigated the role and mechanisms of kallistatin in patients with coronary artery disease ( CAD ), atherosclerotic plaques of apoE-/- mice, and endothelial activation. Methods and Results Plasma kallistatin levels were analyzed in 453 patients at different stages of CAD . Kallistatin levels were significantly lower in patients with CAD and negatively associated with CAD severity and oxidative stress. Human kallistatin cDNA in an adenoviral vector was injected intravenously into apoE-/- mice after partial carotid ligation, with or without nitric oxide synthase inhibitor (Nω-nitro-L-arginine methyl ester) or sirtuin 1 inhibitor (nicotinamide). Kallistatin gene delivery significantly reduced macrophage deposition, oxidative stress, and plaque volume in the carotid artery, compared with control adenoviral injection. Kallistatin administration increased endothelial nitrous oxide synthase, sirtuin 1, interleukin-10, superoxide dismutase 2, and catalase expression in carotid plaques. The beneficial effects of kallistatin in mice were mitigated by Nω-nitro-L-arginine methyl ester or nicotinamide. Furthermore, human kallistatin protein suppressed tumor necrosis factor-α-induced NADPH oxidase activity and increased endothelial nitrous oxide synthase and sirtuin 1 expression in cultured human endothelial cells. These effects were also abolished by Nω-nitro-L-arginine methyl ester or nicotinamide. Conclusions This was the first study to demonstrate that reduced plasma kallistatin levels in patients are associated with CAD severity and oxidative stress. Kallistatin treatment prevents carotid atherosclerotic plaque formation in mice by stimulating the sirtuin 1/endothelial nitrous oxide synthase pathway. These findings indicate the potential protective effects of kallistatin on atherosclerosis in human subjects and mouse models.

Novel protective role of kallistatin in obesity by limiting adipose tissue low grade inflammation and oxidative stress

OBJECTIVE

Kallistatin plays an important role in the inhibition of inflammation, oxidative stress, fibrosis and angiogenesis. We aimed to determine the impact of kallistatin on obesity and its associated metabolic alterations as well as its role in adipocyte inflammation and oxidative stress.

METHODS

Samples obtained from 95 subjects were used in a case-control study. Circulating concentrations and expression levels of kallistatin as well as key inflammation, oxidative stress and extracellular matrix remodelling-related genes were analyzed. Circulating kallistatin concentrations were measured before and after weight loss achieved by Roux-en-Y gastric bypass (RYGB). The impact of kallistatin on lipopolysaccharide (LPS)- and tumour necrosis factor (TNF)-α-mediated inflammatory as well as oxidative stress signalling pathways was evaluated.

RESULTS

We show that the reduced (P < 0.00001) circulating levels of kallistatin in obese patients increased (P < 0.00001) after RYGB. Moreover, gene expression levels of SERPINA4, the gene coding for kallistatin, were downregulated (P < 0.01) in the liver from obese subjects with non-alcoholic fatty liver disease. Additionally, we revealed that kallistatin reduced (P < 0.05) the expression of inflammation-related genes (CCL2, IL1B, IL6, IL8, TNFA, TGFB) and, conversely, upregulated (P < 0.05) mRNA levels of ADIPOQ and KLF4 in human adipocytes in culture. Kallistatin inhibited (P < 0.05) LPS- and TNF-α-induced inflammation in human adipocytes via downregulating the expression and secretion of key inflammatory markers. Furthermore, kallistatin also blocked (P < 0.05) TNF-α-mediated lipid peroxidation as well as NOX2 and HIF1A expression while stimulating (P < 0.05) the expression of SIRT1 and FOXO1.

CONCLUSIONS

These findings provide, for the first time, evidence of a novel role of kallistatin in obesity and its associated comorbidities by limiting adipose tissue inflammation and oxidative stress.

Lower serum kallistatin level is associated with 28-day mortality in patients with septic shock

PURPOSE

Investigation for whether serum levels of kallistatin, vascular cell adhesion molecule-1 (VCAM-1), and E-selectin are associated with outcomes in patients with septic shock MATERIAL AND METHODS: Biomarker levels were measured using blood samples from patients with septic shock at admission, 24 h, and 72 h and from healthy volunteers. The primary outcome was 28-day mortality.

RESULTS

Fifty-eight survivors, fourteen non-survivors, and six healthy volunteers were enrolled. Serum kallistatin level was lower and serum VCAM-1 and E-selectin levels were higher in patients at admission compared with healthy volunteers. Serum kallistatin levels were higher in survivors compared with non-survivors at all time points (4.4 μg/mL [2.9-6.1] vs. 2.5 μg/mL [2.1-5.0], P = 0.019 at admission; 4.3 μg/mL [3.3-5.2] vs. 3.2 μg/mL [2.2-3.8], P = 0.004 at 24 h; 3.1 μg/mL [2.5-4.2] vs. 2.3 μg/mL [1.7-3.1], P = 0.012 at 72 h), while VCAM-1 and E-selectin levels showed no difference. In the multivariable analysis, serum kallistatin level at 24 h was independently associated with 28-day mortality (OR, 0.29; 95% CI, 0.08-0.69, P = 0.024).

CONCLUSIONS

Lower serum kallistatin level at 24 h was independently associated with 28-day mortality in patients with septic shock.

Kallistatin attenuates endothelial senescence by modulating Let-7g-mediated miR-34a-SIRT1-eNOS pathway

Kallistatin, a plasma protein, protects against vascular and organ injury. This study is aimed to investigate the role and mechanism of kallistatin in endothelial senescence. Kallistatin inhibited H2 O2 -induced senescence in human endothelial cells, as indicated by reduced senescence-associated-β-galactosidase activity, p16INK4a and plasminogen activator inhibitor-1 expression, and elevated telomerase activity. Kallistatin blocked H2 O2 -induced superoxide formation, NADPH oxidase levels and VCAM-1, ICAM-1, IL-6 and miR-34a synthesis. Kallistatin reversed H2 O2 -mediated inhibition of endothelial nitric oxide synthase (eNOS), SIRT1, catalase and superoxide dismutase (SOD)-2 expression, and kallistatin alone stimulated the synthesis of these antioxidant enzymes. Moreover, kallistatin's anti-senescence and anti-oxidant effects were attributed to SIRT1-mediated eNOS pathway. Kallistatin, via interaction with tyrosine kinase, up-regulated Let-7g, whereas Let-7g inhibitor abolished kallistatin's effects on miR-34a and SIRT1/eNOS synthesis, leading to inhibition of senescence, oxidative stress and inflammation. Furthermore, lung endothelial cells isolated from endothelium-specific kallistatin knockout mice displayed marked reduction in mouse kallistatin levels. Kallistatin deficiency in mouse endothelial cells exacerbated senescence, oxidative stress and inflammation compared to wild-type mouse endothelial cells, and H2 O2 treatment further magnified these effects. Kallistatin deficiency caused marked reduction in Let-7g, SIRT1, eNOS, catalase and SOD-1 mRNA levels, and elevated miR-34a synthesis in mouse endothelial cells. These findings indicate that endogenous kallistatin through novel mechanisms protects against endothelial senescence by modulating Let-7g-mediated miR-34a-SIRT1-eNOS pathway.

Kallistatin inhibits lymphangiogenesis and lymphatic metastasis of gastric cancer by downregulating VEGF-C expression and secretion

BACKGROUND

Tumor-induced lymphangiogenesis and lymphatic metastasis are predominant during the metastasis of many types of cancers. However, the endogenous inhibitors that counterbalance the lymphangiogenesis and lymphatic metastasis of tumors have not been well evaluated. Kallistatin has been recognized as an endogenous angiogenesis inhibitor.

METHODS AND RESULTS

Our recent study showed for the first time that the lymphatic vessel density (LVD) was reduced in lung and stomach sections from kallistatin-overexpressing transgenic mice. Kallistatin expresses anti-lymphangiogenic activity by inhibiting the proliferation, migration, and tube formation of human lymphatic endothelial cells (hLECs). Therefore, the present study focuses on the relationships of changes in kallistatin expression with the lymphangiogenesis and lymphatic metastasis of gastric cancer and its underlying mechanisms. Our results revealed that the expression of kallistatin in cancer tissues, metastatic lymph nodes, and plasma of gastric cancer patients was significantly downregulated and that the plasma level of kallistatin was negatively associated with the phase of lymph node metastasis. Furthermore, treatment with kallistatin recombinant protein decreased LVD and lymph node metastases in the implanted gastric xenograft tumors of nude mice. Mechanically, kallistatin suppressed the lymphangiogenesis and lymphatic metastasis by downregulating VEGF-C expression and secretion through the LRP6/IKK/IҡB/NF-ҡB signaling pathway in gastric cancer cells.

CONCLUSIONS

These findings demonstrated that kallistatin functions as an endogenous lymphangiogenesis inhibitor and has an important part in the lymphatic metastasis of gastric cancer.

Therapeutic effects of simvastatin combined with kallistatin treatment for pediatric burn patients with sepsis

The aim of the present study was to examine the combined efficacy of simvastatin and kallistatin treatment for pediatric burn sepsis. A total of 72 pediatric patients with burn sepsis were recruited and randomly divided into 3 groups, receiving simvastatin (40 mg/day), kallistatin (20 mg/day) or combined treatment. ELISA, reverse transcription-quantitative polymerase chain reaction, western blotting and flow cytometry were used to analyze the therapeutic effects of simvastatin and kallistatin. The results revealed that combined treatment in pediatric burn sepsis patients decreased the inflammatory cytokine tumor necrosis factor α and interleukin (IL)-1β serum levels, whereas it increased IL-10 and human leukocyte antigen-D related levels. In addition, administration of combined simvastatin and kallistatin decreased the blood urea nitrogen and serum creatinine levels in the patients. It was also demonstrated that Toll-like receptor 4 expression on the surface of monocytes was markedly decreased, while suppressor of cytokine signaling-3 expression was increased in the combined treatment group as compared with the kallistatin or simvastatin treatment alone. Combined treatment also promoted human endothelial cell (HEC) growth compared with the single treatment groups and inhibited the high mobility group box-1 (HMGB1) levels, HMGB1-induced nuclear factor-κB activation and inflammatory gene expression levels in these cells. The study further demonstrated that combined treatment significantly decreased HEC apoptosis through the upregulation of B-cell lymphoma 2 (Bcl-2) and P53 expression levels, as well as downregulation of Bcl-2-associated X protein and caspase-3 levels. In conclusion, these observations indicated that combined treatment with simvastatin and kallistatin inhibited HEC apoptosis, which may be a potential therapeutic strategy for the treatment of pediatric burn sepsis patients.

Cell surface expression of nucleolin mediates the antiangiogenic and antitumor activities of kallistatin

Kallistatin is a unique serine proteinase inhibitor and heparin-binding protein. A previous study conducted by our group indicated that kallistatin has antiangiogenic and antitumoral activities. In the present study, we report that kallistatin specifically binds to membrane surface-expressed nucleolin with high affinity. Antibody-mediated neutralization or siRNA-induced nucleolin knockdown results in loss of kallistatin suppression of endothelial cell proliferation and migration in vitro and tumor angiogenesis and growth in vivo. In addition, we show that kallistatin is internalized and transported into cell nuclei of endothelial cells via nucleolin. Within the nucleus, kallistatin inhibits the phosphorylation of nucleolin, which is a critical step required for cell proliferation. Thus, we demonstrate that nucleolin is a novel functional receptor of kallistatin that mediates its antiangiogenic and antitumor activities. These findings provide mechanistic insights into the inhibitory effects of kallistatin on endothelial cell growth, tumor cell proliferation, and tumor-related angiogenesis.

Opposing Effects of Oxygen Regulation on Kallistatin Expression: Kallistatin as a Novel Mediator of Oxygen-Induced HIF-1-eNOS-NO Pathway

Oxidative stress has both detrimental and beneficial effects. Kallistatin, a key component of circulation, protects against vascular and organ injury. Serum kallistatin levels are reduced in patients and animal models with hypertension, diabetes, obesity, and cancer. Reduction of kallistatin levels is inversely associated with elevated thiobarbituric acid-reactive substance. Kallistatin therapy attenuates oxidative stress and increases endothelial nitric oxide synthase (eNOS) and NO levels in animal models. However, kallistatin administration increases reactive oxygen species formation in immune cells and bacterial killing activity in septic mice. High oxygen inhibits kallistatin expression via activating the JNK-FOXO1 pathway in endothelial cells. Conversely, mild oxygen/hyperoxia stimulates kallistatin, eNOS, and hypoxia-inducible factor-1 (HIF-1) expression in endothelial cells and in the kidney of normal mice. Likewise, kallistatin stimulates eNOS and HIF-1, and kallistatin antisense RNA abolishes oxygen-induced eNOS and HIF-1 expression, indicating a role of kallistatin in mediating mild oxygen's stimulation on antioxidant genes. Protein kinase C (PKC) activation mediates HIF-1-induced eNOS synthesis in response to hyperoxia/exercise; thus, mild oxygen through PKC activation stimulates kallistatin-mediated HIF-1 and eNOS synthesis. In summary, oxidative stress induces down- or upregulation of kallistatin expression, depending on oxygen concentration, and kallistatin plays a novel role in mediating oxygen/exercise-induced HIF-1-eNOS-NO pathway.

Kallistatin: double-edged role in angiogenesis, apoptosis and oxidative stress

Kallistatin, via its two structural elements – an active site and a heparin-binding domain – displays a double-edged function in angiogenesis, apoptosis and oxidative stress. First, kallistatin has both anti-angiogenic and pro-angiogenic effects. Kallistatin treatment attenuates angiogenesis and tumor growth in cancer-bearing mice. Kallistatin via its heparin-binding site inhibits angiogenesis by blocking vascular endothelial growth factor (VEGF)-induced growth, migration and adhesion of endothelial cells. Conversely, kallistatin via the active site promotes neovascularization by stimulating VEGF levels in endothelial progenitor cells. Second, kallistatin inhibits or induces apoptosis depending on cell types. Kallistatin attenuates organ injury and apoptosis in animal models, and its heparin-binding site is essential for blocking tumor necrosis factor (TNF)-α-induced apoptosis in endothelial cells. However, kallistatin via its active site induces apoptosis in breast cancer cells by up-regulating miR-34a and down-regulating miR-21 and miR-203 synthesis. Third, kallistatin can act as an antioxidant or pro-oxidant. Kallistatin treatment inhibits oxidative stress and tissue damage in animal models and cultured cells. Kallistatin via the heparin-binding domain antagonizes TNF-α-induced oxidative stress, whereas its active site is crucial for stimulating antioxidant enzyme expression. In contrast, kallistatin provokes oxidant formation, leading to blood pressure reduction and bacterial killing. Kallistatin-mediated vasodilation is partly mediated by H2O2, as the effect is abolished by the antioxidant enzyme catalase. Moreover, kallistatin exerts a bactericidal effect by stimulating superoxide production in neutrophils of mice with microbial infection as well as in cultured immune cells. Thus, kallistatin’s dual roles in angiogenesis, apoptosis and oxidative stress contribute to its beneficial effects in various diseases.

Kallistatin reduces vascular senescence and aging by regulating microRNA-34a-SIRT1 pathway

Kallistatin, an endogenous protein, protects against vascular injury by inhibiting oxidative stress and inflammation in hypertensive rats and enhancing the mobility and function of endothelial progenitor cells (EPCs). We aimed to determine the role and mechanism of kallistatin in vascular senescence and aging using cultured EPCs, streptozotocin (STZ)‐induced diabetic mice, and Caenorhabditis elegans (C. elegans). Human kallistatin significantly decreased TNF‐α‐induced cellular senescence in EPCs, as indicated by reduced senescence‐associated β‐galactosidase activity and plasminogen activator inhibitor‐1 expression, and elevated telomerase activity. Kallistatin blocked TNF‐α‐induced superoxide levels, NADPH oxidase activity, and microRNA‐21 (miR‐21) and p16^INK4a synthesis. Kallistatin prevented TNF‐α‐mediated inhibition of SIRT1, eNOS, and catalase, and directly stimulated the expression of these antioxidant enzymes. Moreover, kallistatin inhibited miR‐34a synthesis, whereas miR‐34a overexpression abolished kallistatin‐induced antioxidant gene expression and antisenescence activity. Kallistatin via its active site inhibited miR‐34a, and stimulated SIRT1 and eNOS synthesis in EPCs, which was abolished by genistein, indicating an event mediated by tyrosine kinase. Moreover, kallistatin administration attenuated STZ‐induced aortic senescence, oxidative stress, and miR‐34a and miR‐21 synthesis, and increased SIRT1, eNOS, and catalase levels in diabetic mice. Furthermore, kallistatin treatment reduced superoxide formation and prolonged wild‐type C. elegans lifespan under oxidative or heat stress, although kallistatin's protective effect was abolished in miR‐34 or sir‐2.1 (SIRT1 homolog) mutant C. elegans. Kallistatin inhibited miR‐34, but stimulated sir‐2.1 and sod‐3 synthesis in C. elegans. These in vitro and in vivo studies provide significant insights into the role and mechanism of kallistatin in vascular senescence and aging by regulating miR‐34a‐SIRT1 pathway.

Role of Kallistatin Treatment in Aging and Cancer by Modulating miR-34a and miR-21 Expression

Kallistatin is an endogenous protein that regulates differential signaling pathways and a wide spectrum of biological activities via its two structural elements: an active site and a heparin-binding domain. Kallistatin via its heparin-binding site inhibits vascular inflammation and oxidative stress by antagonizing TNF-α-induced NADPH oxidase activity, NF-κB activation, and inflammatory gene expression in endothelial cells. Moreover, kallistatin via its active site inhibits microRNA-34a (miR-34a) synthesis and stimulates eNOS and SIRT1 expression in endothelial progenitor cells, whereas its heparin-binding site is crucial for blocking TNF-α-induced miR-21 expression and oxidative stress, thus reducing cellular senescence. By downregulating miR-34a and miR-21 expression, kallistatin treatment attenuates oxidative damage and aortic senescence in streptozotocin-induced diabetic mice and extends Caenorhabditis elegans lifespan under stress conditions. Likewise, kallistatin through the heparin-binding site inhibits TGF-β-induced miR-21 synthesis and oxidative stress in endothelial cells, resulting in inhibition of endothelial-mesenchymal transition, a process contributing to fibrosis and cancer. Furthermore, kallistatin's active site is essential for stimulating miR-34a and p53 expression and inhibiting the miR-21-Akt-Bcl-2 signaling pathway, thus inducing apoptosis in breast cancer cells. These findings reveal novel mechanisms of kallistatin in protection against senescence, aging, and cancer development by modulating miR-34a and miR-21 levels and inhibiting oxidative stress.

Increased kallistatin levels in patients with obesity and prediabetes compared to normal glucose tolerance

PURPOSE

Kallistatin is a member of serine protease inhibitors (SERPIN) family, which has various functions such as regulation of cardiovascular function and blood vessels development. Its levels are elevated in patients with type 1 and type 2 diabetes with chronic diabetic complications. The aim of the present study was to compare serum kallistatin levels between obese subjects with prediabetes and with normal glucose tolerance.

METHODS

In this study we included 80 subjects at mean age of 50.4 ± 10.6 years, divided into two age and BMI-matched groups - group 1 with obesity without glycemic disturbances (n = 41) and group 2 with obesity and prediabetes (n = 39). Oral glucose tolerance test with measurement of immunoreactive insulin was performed in all participants and levels of kallistatin were measured using ELISA method.

RESULTS

We found significantly higher levels of kallistatin in patients with prediabetes compared to controls (data are presented as median (min; max) because data were not normally distributed) (6.3 (4.4; 9.0) vs. 5.6 (3.1; 8.7) ng/ml; p = 0.022) and in patients with metabolic syndrome compared to those without (6.0 (4.9; 9.0) vs. 5.5 (3.1; 7.7); p = 0.006), but the levels were similar in patients with and without insulin resistance.

CONCLUSIONS

The levels of kallistatin are higher in individuals with prediabetes, but are similar in subjects with and without insulin resistance, which indicates that the main factor for its increased levels may be hyperglycemia and not insulin sensitivity state.

Kallistatin suppresses cancer development by multi-factorial actions

Kallistatin was first identified in human plasma as a tissue kallikrein-binding protein and a serine proteinase inhibitor. Kallistatin via its two structural elements regulates differential signaling cascades, and thus a wide spectrum of biological functions. Kallistatin's active site is essential for: inhibiting tissue kallikrein's activity; stimulating endothelial nitric oxide synthase and sirtuin 1 expression and activation; and modulating the synthesis of the microRNAs, miR-34a, miR-21 and miR-203. Kallistatin's heparin-binding site is crucial for antagonizing the signaling pathways of vascular endothelial growth factor, tumor necrosis factor-α, Wnt, transforming growth factor-β and epidermal growth factor. Circulating kallistatin levels are markedly reduced in patients with prostate and colon cancer. Kallistatin administration attenuates angiogenesis, inflammation, tumor growth and invasion in animal models and cultured cells. Therefore, tumor progression may be substantially suppressed by kallistatin's pleiotropic activities. In this review, we will discuss the role and mechanisms of kallistatin in the regulation of cancer development.

Kallistatin protects against bleomycin-induced idiopathic pulmonary fibrosis by inhibiting angiogenesis and inflammation

Aberrant angiogenesis and vascular remodeling are the main features of idiopathic pulmonary fibrosis. Kallistatin is an anti-angiogenic peptide with known effects on endothelial cells. This study aimed to demonstrate that kallistatin has beneficial effects on bleomycin (BLM)-induced pulmonary fibrosis in a rat model by inhibiting angiogenesis. Twenty-five rats were randomly divided into five experimental groups: (A) Saline only (SA)-as the negative control, (B) BLM only (BLM)-as the model group, (C) BLM and 0.1 mg/kg kallistatin (L-Kal), (D) BLM and 0.5 mg/kg kallistatin (M-Kal), and (E) BLM and 2.5 mg/kg kallistatin (H-Kal). Fibrillar collagen was quantified by Masson's trichrome and hematoxylin-eosin staining. Transforming growth factor-β1 (TGF-β1), α-smooth-muscle-actin (α-SMA) and microvascular density (MVD) were measured by immunohistochemistry. Vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGFR), and tumor necrosis factor-α (TNF-α) were assayed by Western immunoblotting or ELISA. Daily administration of kallistatin attenuated fibrosis in BLM-induced pulmonary fibrosis, as shown by histology. During inflammation from BLM-induced pulmonary fibrosis, kallistatin reduced the number of inflammatory cells infiltrating the bronchoalveolar lavage fluid. Kallistatin also inhibited VEGF expression and phosphorylation of VEGFR2 (Flk-1). In vitro, kallistatin blocked tube formation by inhibiting Flk-1 and GSK-3β phosphorylation. The results demonstrated that continuous administration of kallistatin attenuated BLM-induced pulmonary fibrosis and improved survival of BLM rats. Reducing pulmonary fibrosis was achieved by partial inhibition of pulmonary inflammation and angiogenesis.

Kallistatin protects against diabetic nephropathy in db/db mice by suppressing AGE-RAGE-induced oxidative stress

Kallistatin is a serine protease inhibitor with anti-inflammatory, anti-angiogenic, and anti-oxidative properties. Since oxidative stress plays a critical role in the pathogenesis of diabetic nephropathy, we studied the effect and mechanisms of action of kallistatin superinduction. Using ultrasound-microbubble-mediated gene transfer, kallistatin overexpression was induced in kidney tubules. In db/db mice, kallistatin overexpression reduced serum creatinine and BUN levels, ameliorated glomerulosclerosis and tubulointerstitial injury, and attenuated renal fibrosis by inhibiting TGF-β signaling. Additionally, downstream PAI-1 and collagens I and IV expression were reduced and kallistatin partially suppressed renal inflammation by inhibiting NF-κB signaling and decreasing tissue kallikrein activity. Kallistatin lowered blood pressure and attenuated oxidative stress as evidenced by suppressed levels of NADPH oxidase 4, and oxidative markers (nitrotyrosine, 8-hydroxydeoxyguanosine, and malondialdehyde) in diabetic renal tissue. Kallistatin also inhibited RAGE expression in the diabetic kidney and AGE-stimulated cultured proximal tubular cells. Reduced AGE-induced reactive oxygen species generation reflected an anti-oxidative mechanism via the AGE-RAGE-reactive oxygen species axis. These results indicate a renoprotective role of kallistatin against diabetic nephropathy by multiple mechanisms including suppression of oxidative stress, anti-fibrotic and anti-inflammatory actions, and blood pressure lowering.

Kallistatin Suppresses Cell Proliferation and Invasion and Promotes Apoptosis in Cervical Cancer Through Blocking NF-κB Signaling

Kallistatin has been recognized as an endogenous angiogenesis inhibitor and exerts pleiotropic effects in inhibiting tumor growth, migration, apoptosis, and inflammation. The purpose of the present study was to investigate the potential role and mechanisms of kallistatin in cervical cancer. We demonstrated that kallistatin effectively inhibited cell proliferation and enhanced apoptosis in a dose-dependent manner. Additionally, kallistatin suppressed migration and invasion activities and markedly reduced the expression of matrix-degrading metalloproteinases, progelatinase (MMP-2), MMP-9, and urokinase-type PA (uPA). Kallistatin reversed the epithelial-mesenchymal transition (EMT) and caused the upregulation of epithelial markers such as E-cadherin and inhibited mesenchymal markers such as N-cadherin and vimentin. Moreover, kallistatin led to a marked decrease in the expression of vascular endothelial growth factor (VEGF) and HIF-1α. In a xenograft mouse model, kallistatin treatment reduced tumor growth. Importantly, kallistatin strikingly impeded NF-κB activation by suppressing IκBα degradation and the level of phosphorylation of p65. Interestingly, similar to kallistatin, treatment with PDTC (an inhibitor of NF-κB) also attenuated cell invasion and migration. Taken together, these findings suggest that kallistatin suppresses cervical cancer cell proliferation, migration, and EMT and promotes cell apoptosis by blocking the NF-κB signaling pathway, suggesting that kallistatin may be a novel therapeutic target for cervical cancer treatment.

Kallistatin levels in HIV-infected patients and effects of statin therapy

BACKGROUND

Kallistatin, a serine proteinase inhibitor, has vasodilatory and anti-inflammatory properties and is increased in other inflammatory conditions. We measured kallistatin in HIV for the first time, examined its relationship with inflammation, and determined if statin therapy affected levels.

METHODS

Kallistatin levels were measured in subjects from a randomized, double-blinded, placebo-controlled trial.

RESULTS

One hundred and thirty-five HIV-infected subjects were included. Kallistatin levels were 28.4 μg/mL at baseline and not affected by rosuvastatin. Levels were correlated with high-sensitivity C-reactive protein (hsCRP), interleukin-6, fibrinogen and insulin resistance.

CONCLUSIONS

Kallistatin levels were correlated with some markers of systemic inflammation and should be further explored in the HIV population.

The Potential Role of Kallistatin in the Development of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a vascular condition that causes permanent dilation of the abdominal aorta, which can lead to death due to aortic rupture. The only treatment for AAA is surgical repair, and there is no current drug treatment for AAA. Aortic inflammation, vascular smooth muscle cell apoptosis, angiogenesis, oxidative stress and vascular remodeling are implicated in AAA pathogenesis. Kallistatin is a serine proteinase inhibitor, which has been shown to have a variety of functions, potentially relevant in AAA pathogenesis. Kallistatin has been reported to have inhibitory effects on tumor necrosis factor alpha (TNF-α) signaling induced oxidative stress and apoptosis. Kallistatin also inhibits vascular endothelial growth factor (VEGF) and Wnt canonical signaling, which promote inflammation, angiogenesis, and vascular remodeling in various pre-clinical experimental models. This review explores the potential protective role of kallistatin in AAA pathogenesis.

SERPINA4 is a novel independent prognostic indicator and a potential therapeutic target for colorectal cancer

Serpina family A member 4 (SERPINA4), also known as kallistatin, exerts important effects in inhibiting tumor growth and angiogenesis in many malignancies. However, the precise role of SERPINA4 in CRC has not been fully elucidated. The present study aimed to investigate the expression of SERPINA4 and its clinical significance in CRC. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analyses showed that the mRNA and protein expression of SERPINA4 in colorectal cancer (CRC) specimens was significantly decreased than that in adjacent normal mucosa. Immunohistochemistry (IHC) was conducted to characterize the expression pattern of SERPINA4 by using a tissue microarray (TMA) containing 327 archived paraffin-embedded CRC specimens. Statistical analyses revealed that decreased SERPINA4 expression was significantly associated with invasion depth, nodal involvement, distant metastasis, American Joint Committee on Cancer (AJCC) stage, and tumor differentiation. SERPINA4 was also an independent prognostic indicator of disease-free survival and overall survival in patients with CRC. Furthermore, the impact of altered SERPINA4 expression on CRC cells was analyzed with a series of in vitro and in vivo assays. The results demonstrated that SERPINA4 significantly inhibits malignant tumor progression and serves as a novel prognostic indicator and a potential therapeutic target for CRC.

Global gene expression profiling using heterologous DNA microarrays to analyze alterations in the transcriptome of Mus spretus mice living in a heavily polluted environment

Microarray platforms are a good approach for assessing biological responses to pollution as they enable the simultaneous analyses of changes in the expression of thousands of genes. As an omic and non-targeted methodology, this technique is open to unforeseen responses under particular environmental conditions. In this study, we successfully apply a commercial oligonucleotide microarray containing Mus musculus whole-genome probes to compare and assess the biological effects of living in a heavily polluted settlement, the Domingo Rubio stream (DRS), at the Huelva Estuary (SW Spain), on inhabitant free-living Mus spretus mice. Our microarray results show that mice living in DRS suffer dramatic changes in gene and protein expression compared with reference specimens. DRS mice showed alteration in the oxidative status of hepatocytes, with activation of both the innate and the acquired immune responses and the induction of chronic inflammation, accompanied by metabolic alterations that imply the accumulation of lipids in the liver (hepatic steatosis). The identified deregulated genes may be useful as biomarkers of environmental pollution.

Kallistatin induces breast cancer cell apoptosis and autophagy by modulating Wnt signaling and microRNA synthesis

Kallistatin is an endogenous protein that regulates differential signaling pathways and biological functions. Our previous studies showed that kallistatin gene therapy inhibited angiogenesis, tumor growth and metastasis in mice, and kallistatin protein suppressed Wnt-mediated growth, migration and invasion by blocking Wnt/β-catenin signaling pathway in breast cancer cells. In this study, we show that kallistatin reduced cell viability, and increased apoptotic cell death and caspase-3 activity in MDA-MB-231 breast cancer cells. Kallistatin also induced cancer cell autophagy, as evidenced by increased LC3B levels and elevated Atg5 and Beclin-1 expression; however, co-administration of Wnt or PPARγ antagonist GW9662 abolished these effects. Moreover, kallistatin via its heparin-binding site antagonized Wnt3a-induced cancer cell proliferation and increased PPARγ expression. Kallistatin inhibited oncogenic miR-21 synthesis associated with reduced Akt phosphorylation and Bcl-2 synthesis, but increased BAX expression. Kallistatin via PKC-ERK activation reduced miR-203 levels, leading to increased expression of suppressor of cytokine signaling 3 (SOCS3), a tumor suppressor. Conversely, kallistatin stimulated expression of the tumorigenic suppressors miR-34a and p53. Kallistatin's active site is essential for suppressing miR-21 and miR-203, and stimulating miR-34a and SOCS3 expression. This is the first study to demonstrate that kallistatin's heparin-binding site is essential for inhibiting Wnt-mediated effects, and its active site plays a key role in regulating miR-21, miR-203, miR-34a and SOCS3 synthesis in breast cancer cells. These findings reveal novel mechanisms of kallistatin in inducing apoptosis and autophagy in breast cancer cells, thus inhibiting tumor progression by regulation of Wnt/PPARγ signaling, as well as miR-21, miR-203 and miR-34a synthesis.

Kallistatin ameliorates influenza virus pathogenesis by inhibition of kallikrein-related peptidase 1-mediated cleavage of viral hemagglutinin

Proteolytic cleavage of the hemagglutinin (HA) of influenza virus by host trypsin-like proteases is required for viral infectivity. Some serine proteases are capable of cleaving influenza virus HA, whereas some serine protease inhibitors (serpins) inhibit the HA cleavage in various cell types. Kallikrein-related peptidase 1 (KLK1, also known as tissue kallikrein) is a widely distributed serine protease. Kallistatin, a serpin synthesized mainly in the liver and rapidly secreted into the circulation, forms complexes with KLK1 and inhibits its activity. Here, we investigated the roles of KLK1 and kallistatin in influenza virus infection. We show that the levels of KLK1 increased, whereas those of kallistatin decreased, in the lungs of mice during influenza virus infection. KLK1 cleaved H1, H2, and H3 HA molecules and consequently enhanced viral production. In contrast, kallistatin inhibited KLK1-mediated HA cleavage and reduced viral production. Cells transduced with the kallistatin gene secreted kallistatin extracellularly, which rendered them more resistant to influenza virus infection. Furthermore, lentivirus-mediated kallistatin gene delivery protected mice against lethal influenza virus challenge by reducing the viral load, inflammation, and injury in the lung. Taking the data together, we determined that KLK1 and kallistatin contribute to the pathogenesis of influenza virus by affecting the cleavage of the HA peptide and inflammatory responses. This study provides a proof of principle for the potential therapeutic application of kallistatin or other KLK1 inhibitors for influenza. Since proteolytic activation also enhances the infectivity of some other viruses, kallistatin and other kallikrein inhibitors may be explored as antiviral agents against these viruses.

Kallistatin inhibits TGF-β-induced endothelial-mesenchymal transition by differential regulation of microRNA-21 and eNOS expression

Kallistatin, an endogenous protein, consists of two structural elements: active site and heparin-binding domain. Kallistatin exerts beneficial effects on fibrosis by suppressing transforming growth factor (TGF)-β synthesis in animal models. TGF-β is the most potent inducer of endothelial-mesenchymal transition (EndMT), which contributes to fibrosis and cancer. MicroRNA (miR)-21 is an important player in organ fibrosis and tumor invasion. Here we investigated the potential role of kallistatin in EndMT via modulation of miR-21 in endothelial cells. Human kallistatin treatment blocked TGF-β-induced EndMT, as evidenced by morphological changes as well as increased endothelial and reduced mesenchymal marker expression. Kallistatin also inhibited TGF-β-mediated reactive oxygen species (ROS) formation and NADPH oxidase expression and activity. Moreover, kallistatin antagonized TGF-β-induced miR-21 and Snail1 synthesis, Akt phosphorylation, NF-κB activation, and matrix metalloproteinase 2 (MMP2) synthesis and activation. Kallistatin via its heparin-binding site blocked TGF-β-induced miR-21, Snail1 expression, and ROS formation, as wild-type kallistatin, but not heparin-binding site mutant kallistatin, exerted the effect. Conversely, kallistatin through its active site stimulated the synthesis of endothelial nitric oxide synthase (eNOS), sirtuin 1 (Sirt1) and forkhead box O1 (FoxO1); however, these effects were blocked by genistein, a tyrosine kinase inhibitor. This is the first study to demonstrate that kallistatin's heparin-binding site is crucial for preventing TGF-β-induced miR-21 and oxidative stress, while its active site is key for stimulating the expression of antioxidant genes via interaction with an endothelial surface tyrosine kinase. These findings reveal novel mechanisms of kallistatin in protection against fibrosis and cancer by suppressing EndMT.

Kallistatin, a new and reliable biomarker for the diagnosis of liver cirrhosis

Kallistatin, which protects organs and cells against inflammation, fibrosis and oxidative stress, is mainly synthesized and secreted in liver. However, its relationship to human liver disease remains unclear. The purpose of this study was to explore the relationship between serum kallistatin and clinical evidence of both cirrhosis and hepatocellular carcinoma (HCC), and to determine if serum kallistatin levels could be used as a diagnostic indicator of hepatic health status, especially human liver cirrhosis (LC). Our cohort consisted of 115 patients with clinically proven liver fibrosis (LF), LC, or HCC by liver biopsies, and 31 healthy controls (CON). Serum kallistatin levels were quantified by ELISA. Results of the present study demonstrated that irrespective of the underlying etiology, serum kallistatin levels were significantly lower in the LF/LC group when compared with the CON group. A decrease in serum kallistatin levels appeared to reflect the extent of cirrhosis, with the lowest levels associated with higher grades of cirrhosis. Patients with LC had a noticeable correlation between serum kallistatin levels and other serum biochemical indicators. The area under the curve (AUC) for LC, viral liver cirrhosis (VLC) and alcoholic liver cirrhosis (ALC) was 0.845, 0.757 and 0.931, respectively. In conclusion, our findings demonstrated that kallistatin, a plasma protein produced by the liver, can be a useful and reliable diagnostic indicator of hepatic health status, especially for LC.

Kallistatin treatment attenuates lethality and organ injury in mouse models of established sepsis

INTRODUCTION

Kallistatin levels in the circulation are reduced in patients with sepsis and liver disease. Transgenic mice expressing kallistatin are resistant to lipopolysaccharide (LPS)-induced mortality. Here, we investigated the effect of kallistatin on survival and organ damage in mouse models of established sepsis.

METHODS

Mice were rendered septic by cecal ligation and puncture (CLP), or endotoxemic by LPS injection. Recombinant human kallistatin was administered intravenously six hours after CLP, or intraperitoneally four hours after LPS challenge. The effect of kallistatin treatment on organ damage was examined one day after sepsis initiation, and mouse survival was monitored for four to six days.

RESULTS

Human kallistatin was detected in mouse serum of kallistatin-treated mice. Kallistatin significantly reduced CLP-induced renal injury as well as blood urea nitrogen, serum creatinine, interleukin-6 (IL-6), and high mobility group box-1 (HMGB1) levels. In the lung, kallistatin decreased malondialdehyde levels and HMGB1 and toll-like receptor-4 (TLR4) synthesis, but increased suppressor of cytokine signaling-3 (SOCS3) expression. Moreover, kallistatin attenuated liver injury, serum alanine transaminase (ALT) levels and hepatic tumor necrosis factor-α (TNF-α) synthesis. Furthermore, delayed kallistatin administration improved survival in CLP mice by 38%, and LPS-treated mice by 42%. In LPS-induced endotoxemic mice, kallistatin attenuated kidney damage in association with reduced serum creatinine, IL-6 and HMGB1 levels, and increased renal SOCS3 expression. Kallistatin also decreased liver injury in conjunction with diminished serum ALT levels and hepatic TNF-α and TLR4 expression. In cultured macrophages, kallistatin through its active site increased SOCS3 expression, but this effect was blocked by inhibitors of tyrosine kinase, protein kinase C and extracellular signal-regulated kinase (ERK), indicating that kallistatin stimulates a tyrosine-kinase-protein kinase C-ERK signaling pathway.

CONCLUSIONS

This is the first study to demonstrate that delayed human kallistatin administration is effective in attenuating multi-organ injury, inflammation and mortality in mouse models of polymicrobial infection and endotoxemia. Thus, kallistatin therapy may provide a promising approach for the treatment of sepsis in humans.

Novel role of kallistatin in vascular repair by promoting mobility, viability, and function of endothelial progenitor cells

Background

Kallistatin exerts pleiotropic activities in inhibiting inflammation, apoptosis, and oxidative stress in endothelial cells. Because endothelial progenitor cells (EPCs) play a significant role in vascular repair, we investigated whether kallistatin contributes to vascular regeneration by enhancing EPC migration and function.

Methods and Results

We examined the effect of endogenous kallistatin on circulating EPCs in a rat model of vascular injury and the mechanisms of kallistatin on EPC mobility and function in vitro. In deoxycorticosterone acetate–salt hypertensive rats, we found that kallistatin depletion augmented glomerular endothelial cell loss and diminished circulating EPC number, whereas kallistatin gene delivery increased EPC levels. In cultured EPCs, kallistatin significantly reduced tumor necrosis factor‐α–induced apoptosis and caspase‐3 activity, but kallistatin's effects were blocked by phosphoinositide 3‐kinase inhibitor (LY294002) and nitric oxide (NO) synthase inhibitor (l‐NAME). Kallistatin stimulated the proliferation, migration, adhesion and tube formation of EPCs; however, kallistatin's actions were abolished by LY294002, l‐NAME, endothelial NO synthase–small interfering RNA, constitutively active glycogen synthase kinase‐3β, or vascular endothelial growth factor antibody. Kallistatin also increased Akt, glycogen synthase kinase‐3β, and endothelial NO synthase phosphorylation; endothelial NO synthase, vascular endothelial growth factor, and matrix metalloproteinase‐2 synthesis and activity; and NO and vascular endothelial growth factor levels. Kallistatin's actions on phosphoinositide 3‐kinase–Akt signaling were blocked by LY294002, l‐NAME, and anti–vascular endothelial growth factor antibody.

Conclusions

Endogenous kallistatin plays a novel role in protection against vascular injury in hypertensive rats by promoting the mobility, viability, and vasculogenic capacity of EPCs via enhancing NO and vascular endothelial growth factor levels through activation of phosphoinositide 3‐kinase–Akt signaling. Kallistatin therapy may be a promising approach in the treatment of vascular diseases.

Human kallistatin administration reduces organ injury and improves survival in a mouse model of polymicrobial sepsis

Kallistatin, a plasma protein, has been shown to exert multi-factorial functions including inhibition of inflammation, oxidative stress and apoptosis in animal models and cultured cells. Kallistatin levels are reduced in patients with sepsis and in lipopolysaccharide (LPS)-induced septic mice. Moreover, transgenic mice expressing kallistatin are more resistant to LPS-induced mortality. Here, we investigated the effects of human kallistatin on organ injury and survival in a mouse model of polymicrobial sepsis. In this study, mice were injected intravenously with recombinant kallistatin (KS3, 3 mg/kg; or KS10, 10 mg/kg body weight) and then rendered septic by caecal ligation and puncture 30 min later. Kallistatin administration resulted in a > 10-fold reduction of peritoneal bacterial counts, and significantly decreased serum tumour necrosis factor-α, interleukin-6 and high mobility group box-1 (HMGB1) levels. Kallistatin also inhibited HMGB1 and toll-like receptor-4 gene expression in the lung and kidney. Administration of kallistatin attenuated renal damage and decreased blood urea nitrogen and serum creatinine levels, but increased endothelial nitric oxide synthase and nitric oxide levels in the kidney. In cultured endothelial cells, human kallistatin via its heparin-binding site inhibited HMGB1-induced nuclear factor-κB activation and inflammatory gene expression. Moreover, kallistatin significantly reduced apoptosis and caspase-3 activity in the spleen. Furthermore, kallistatin treatment markedly improved the survival of septic mice by 23% (KS3) and 41% (KS10). These results indicate that kallistatin is a unique protecting agent in sepsis-induced organ damage and mortality by inhibiting inflammation and apoptosis, as well as enhancing bacterial clearance in a mouse model of polymicrobial sepsis.

Heterologous microarray analysis of transcriptome alterations in Mus spretus mice living in an industrial settlement

This work demonstrates the successful application of a commercial oligonucleotide microarray containing Mus musculus whole-genome probes to assess the biological effects of an industrial settlement on inhabitant Mus spretus mice. The transcriptomes of animals in the industrial settlement contrasted with those of specimens collected from a nearby protected ecosystem. Proteins encoded by the differentially expressed genes were broadly categorized into six main functional classes. Immune-associated genes were mostly induced and related to innate and acquired immunity and inflammation. Genes sorted into the stress-response category were mainly related to oxidative-stress tolerance and biotransformation. Metabolism-associated genes were mostly repressed and related to lipid metabolic pathways; these included genes that encoded 11 of the 20 cholesterol biosynthetic pathway enzymes. Crosstalk between members of different functional categories was also revealed, including the repression of serine-protease genes and the induction of protease-inhibitor genes to control the inflammatory response. Absolute quantification of selected transcripts was performed via RT-PCR to verify the microarray results and assess interindividual variability. Microarray data were further validated by immunoblotting and by cholesterol and protein-thiol oxidation level determinations. Reported data provide a broad impression of the biological consequences of residing in an industrial area.