Utility of serum chemokine-like factor 1 as a biomarker of severity and prognosis after severe traumatic brain injury: A prospective observational study.

BACKGROUND: Chemokine-like factor 1 (CKLF1) may be involved in the inflammatory response and secondary brain injury after severe traumatic brain injury (sTBI). We determined serum CKLF1 levels of sTBI patients to further investigate the correlation of CKLF1 levels with disease severity, functional prognosis, and 180-day mortality of sTBI. METHODS: Serum CKLF1 levels were measured at admission in 119 sTBI patients and at entry into study in 119 healthy controls. Serum CKLF levels of 50 patients were also quantified at days 1-3, 5, and 7 after admission. Glasgow coma scale (GCS) scores and Rotterdam computerized tomography (CT) classification were utilized to assess disease severity. Extended Glasgow outcome scale (GOSE) scores were recorded to evaluate function prognosis at 180 days after sTBI. Relations of serum CKLF1 levels to 180-day poor prognosis (GOSE scores of 1-4) and 180-day mortality were analyzed using univariate analysis, followed by multivariate analysis. Receiver-operating characteristic (ROC) curve was built to investigate prognostic predictive capability. RESULTS: Serum CKLF1 levels of sTBI patients increased at admission, peaked at day 2, and then gradually decreased; they were significantly higher during the 7 days after sTBI than in healthy controls. Differences of areas under ROC curve (areas under the curve [AUCs]) were not significant among the six time points. Multivariate analysis showed that serum CKLF1 levels were independently correlated with GCS scores, Rotterdam CT classification, and GOSE scores. Serum CKLF1 levels were significantly higher in non-survivors than in survivors and in poor prognosis patients than in good prognosis patients. Serum CKLF1 levels independently predicted 180-day poor prognosis and 180-day mortality, and had high 180-day prognosis and mortality predictive abilities, and their AUCs were similar to those of GCS scores and Rotterdam CT classification. Combination model containing serum CKLF1, GCS scores, and Rotterdam CT classification performed more efficiently than any of them alone in predicting mortality and poor prognosis. The models were visually described using nomograms, which were comparatively stable under calibration curve and were relatively of clinical benefit under decision curve. CONCLUSION: Serum CKLF1 levels are significantly associated with disease severity, poor 180-day prognosis, and 180-day mortality in sTBI patients. Hence, complement CKLF1 may serve as a potential prognostic biomarker of sTBI.

CKLF induces microglial activation via triggering defective mitophagy and mitochondrial dysfunction.

Although microglial activation is induced by an increase in chemokines, the role of mitophagy in this process remains unclear. This study aimed to elucidate the role of microglial mitophagy in CKLF/CKLF1 (chemokine-like factor 1)-induced microglial activation and neuroinflammation, as well as the underlying molecular mechanisms following CKLF treatment. This study determined that CKLF, an inducible chemokine in the brain, leads to an increase in mitophagy markers, such as DNM1L, PINK1 (PTEN induced putative kinase 1), PRKN, and OPTN, along with a simultaneous increase in autophagosome formation, as evidenced by elevated levels of BECN1 and MAP1LC3B (microtubule-associated protein 1 light chain 3 beta)-II. However, SQSTM1, a substrate of autophagy, was also accumulated by CKLF treatment, suggesting that mitophagy flux was reduced and mitophagosomes accumulated. These findings were confirmed by transmission electron microscopy and confocal microscopy. The defective mitophagy observed in our study was caused by impaired lysosomal function, including mitophagosome-lysosome fusion, lysosome generation, and acidification, resulting in the accumulation of damaged mitochondria in microglial cells. Further analysis revealed that pharmacological blocking or gene-silencing of mitophagy inhibited CKLF-mediated microglial activation, as evidenced by the expression of the microglial marker AIF1 (allograft inflammatory factor 1) and the mRNA of proinflammatory cytokines (Tnf and Il6). Ultimately, defective mitophagy induced by CKLF results in microglial activation, as observed in the brains of adult mice. In summary, CKLF induces defective mitophagy, microglial activation, and inflammation, providing a potential approach for treating neuroinflammatory diseases.Abbreviation: 3-MA: 3-methyladenine; AIF1: allograft inflammatory factor 1; ANOVA: analysis of variance; BAF: bafilomycin A1; BSA: bovine serum albumin; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; cGAMP: cyclic GMP-AMP; CGAS: cyclic GMP-AMP synthase; CKLF/CKLF1: chemokine-like factor 1; CNS: central nervous system; DMEM: Dulbecco's Modified Eagle Medium; DNM1L: dynamin 1 like; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescence protein; IRF3: interferon regulatory factor 3; IgG: immunoglobulin G; LAMP1: lysosomal-associated membrane protein 1; LAPTM4A: lysosomal-associated protein transmembrane 4A; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; Mdivi-1: mitochondrial division inhibitor 1; mRFP: monomeric red fluorescent protein; mtDNA: mitochondrial DNA; MTORC1: mechanistic target of rapamycin kinase complex 1; OPTN: optineurin; PBS: phosphate-buffered saline; PCR: polymerase chain reaction; PINK1: PTEN induced putative kinase 1; PLL: poly-L-lysine; PRKN: parkin RBR E3 ubiquitin protein ligase; qPCR: quantitative polymerase chain reaction; ROS: reactive oxygen species; SQSTM1: sequestosome 1; TBK1: TANK-binding kinase 1; TFEB: transcription factor EB; VDAC: voltage-dependent anion channel.

Ginsenoside Rg1 treats ischemic stroke by regulating CKLF1/CCR5 axis-induced neuronal cell pyroptosis.

BACKGROUND: Ischemic stroke, a severe and life-threatening neurodegenerative condition, currently relies on thrombolytic therapy with limited therapeutic window and potential risks of hemorrhagic transformation. Thus, there is a crucial need to explore novel therapeutic agents for ischemic stroke. Ginsenoside Rg1 (Rg1), a potential neuroprotective agent, exhibits anti-ischemic effects attributed to its anti-inflammatory, anti-oxidant, and anti-apoptotic properties. Nevertheless, the precise underlying mechanism of action remains to be fully elucidated. PURPOSE: This study aimed to explore whether Rg1 exerts anti-ischemic stroke effects by inhibiting pyroptotic neuronal cell death through modulation of the chemokine like factor 1 (CKLF1)/ C-C chemokine receptor type 5 (CCR5) axis. METHODS: In this study, the MCAO model was used as an ischemic stroke model, and experimental tests were performed after 6 hours of ischemia. The anti-ischemic effect of Rg1 was examined by TTC staining, nissl-staining and neurobehavioral tests. In the in vitro experiments, PC12 cells were subjected to stimulation with CKLF1's mimetic peptide C27 to assess the potential of CKLF1 to induce focal neuronal cell death. Additionally, the impact of CKLF1 mimetic peptide C27, antagonistic peptide C19, and CCR5 inhibitor MVC on PC12 cells subjected to oxygen-glucose deprivation (OGD) and subsequently treated with Rg1 was investigated. In vivo, Rg1 treatment was examined by quantitative real-time PCR (qPCR), ELISA, immunohistochemistry (IHC), immunofluorescence (IF), western blot (WB), and co-immunoprecipitate (Co-IP) assays to perspective whether Rg1 treatment reduces CKLF1/CCR5 axis-induced pyroptotic neuronal cell death. In addition, to further explore the biological significance of CKLF1 in ischemic stroke, CKLF1-/- rats were used as the observation subjects in this study. RESULTS: The in vitro results suggested that CKLF1 was able to induce neuronal cells to undergo pyroptosis. In vivo pharmacodynamic results showed that Rg1 treatment was able to significantly improve symptoms in ischemic stroke rats. In addition, Rg1 treatment was able to inhibit the interaction between CKLF1 and CCR5 after ischemic stroke and inhibited CKLF1/CCR5 axis-induced pyroptosis. The results of related experiments in CKLF1-/- rats showed that Rg1 lost its therapeutic effect after CKLF1 knockdown. CONCLUSION: Our findings indicate that the activation of the NLRP3 inflammasome is initiated by the CKLF1/CCR5 axis, facilitated through the activation of the NF-κB pathway, ultimately resulting in the pyroptosis of neuronal cells. Conversely, Rg1 demonstrates the capability to mitigate neuronal cell damage following CKLF1-induced effects by suppressing the expression of CKLF1. Thus, CKLF1 represents a crucial target for Rg1 in the context of cerebral ischemia treatment, and it also holds promise as a potential target for drug screening in the management of ischemic stroke.

CKLF1 interference alleviates IL­1ß­induced inflammation, apoptosis and degradation of the extracellular matrix in chondrocytes via CCR5.

Osteoarthritis (OA) is a type of joint disease with a rising prevalence and incidence among the elderly across the global population. Chemokine-like factor 1 (CKLF1) is a human cytokine, which has been demonstrated to be involved in the progression of multiple human diseases. However, little attention has been paid to the impact of CKLF1 on OA. The present study was designed to identify the role of CKLF1 in OA and to clarify the regulatory mechanism. The expression levels of CKLF1 and its receptor CC chemokine receptor 5 (CCR5) were examined by reverse transcription-quantitative PCR (RT-qPCR) and western blotting. A Cell Counting Kit-8 assay was used to estimate cell viability. The levels and expression of inflammatory factors were determined by ELISA and RT-qPCR, respectively. Apoptosis was investigated by TUNEL assays and the protein levels of apoptosis-related factors were analyzed by western blotting. RT-qPCR and western blotting were used to examine the expression of extracellular matrix (ECM) degradation-associated proteins and ECM components. Dimethylmethylene blue analysis was used to analyze the production of soluble glycosamine sulfate additive. A co-immunoprecipitation assay was used to confirm the protein interaction between CKLF1 and CCR5. The results revealed that CKLF1 expression was increased in IL-1ß-exposed murine chondrogenic ATDC5 cells. Furthermore, CKLF1 silencing enhanced the viability of IL-1ß-induced ATDC5 cells, while inflammation, apoptosis and degradation of the ECM were reduced. Additionally, CKLF1 knockdown led to decreased CCR5 expression in IL-1ß-challenged ATDC5 cells, and CKLF1 bound with CCR5. The enhanced viability, as well as the suppressed inflammation, apoptosis and degradation of the ECM, following CKLF1 knockdown in the IL-1ß-induced ATDC5 cells were all restored after CCR5 was overexpressed. In conclusion, CKLF1 might serve a detrimental role in the development of OA by targeting its receptor CCR5.

Role of chemokine-like factor 1 as an inflammatory marker in diseases.

Immunoinflammatory mechanisms have been incrementally found to be involved in the pathogenesis of multiple diseases, with chemokines being the main drivers of immune cell infiltration in the inflammatory response. Chemokine-like factor 1 (CKLF1), a novel chemokine, is highly expressed in the human peripheral blood leukocytes and exerts broad-spectrum chemotactic and pro-proliferative effects by activating multiple downstream signaling pathways upon binding to its functional receptors. Furthermore, the relationship between CKLF1 overexpression and various systemic diseases has been demonstrated in both in vivo and in vitro experiments. In this context, it is promising that clarifying the downstream mechanism of CKLF1 and identifying its upstream regulatory sites can yield new strategies for targeted therapeutics of immunoinflammatory diseases.

Inhibition of CKLF1 ameliorates hepatic ischemia-reperfusion injury via MAPK pathway.

BACKGROUND: Hepatic ischemia/reperfusion (I/R) injury is a major complication of liver resection or transplantation. However, the mechanism underlying hepatic I/R injury remains obscure. The aim of the present study was to investigate the role of Chemokine-like factor 1 (CKLF1) in hepatic I/R injury. METHODS: Rats were subjected to 70% hepatic ischemia for 90 min, followed by 6, 12, 24, 48 and 96 h of reperfusion. The expression of CKLF1 was measured by real-time PCR and western blot. The effect of C19, an antagonism peptide of CKLF1, on hepatic I/R injury was investigated. RESULTS: After subjected to 70% hepatic ischemia and reperfusion, the ALT and AST were increased. H&E results showed serious liver damage. The mRNA and protein levels of CKLF1 expression were upregulated during hepatic I/R. Immunohistochemistry staining results showed that neutrophil infiltration was increased in the ischemia lobe. MPO activity was significantly higher post reperfusion. TNF-α and IL-1ß were upregulated during hepatic I/R. C19 administration significantly reduced the level of ALT and AST, decreased the necrosis area of liver tissue. Furthermore, C19 treatment inhibited neutrophil infiltration and reduced MPO activity. Meanwhile, C19 decreased the expression of TNF-α and IL-1ß. The phosphorylation of P38, JNK were inhibited by C19 treatment. CONCLUSION: CKLF1 was upregulated during hepatic I/R. Inhibiting CKLF1 by C19, an antagonism peptide of CKLF1, could alleviate hepatic I/R injury, reduce neutrophil infiltration, decrease inflammatory response. The protective effect of C19 may related to MAPK signaling pathway.

Chemokine-like factor 1 (CKLF1) aggravates neointimal hyperplasia through activating the NF-κB /VCAM-1 pathway.

Neointimal hyperplasia (NIH) is a complicated inflammatory process contributing to vascular restenosis. The present study aimed to explore whether chemokine-like factor 1 (CKLF1) aggravates NIH via the nuclear factor-kappa B (NF-κB)/vascular cell adhesion molecule-1 (VCAM-1) pathway. We found the expression of CKLF1 and VCAM-1 significantly increased in human carotid plaques compared to the control. In vivo, CKLF1 overexpression induced a thicker neointimal formation and VCAM-1 expression was correspondingly upregulated. In vitro, CKLF1 activated NF-κB and induced VCAM-1 upregulation in human aortic smooth muscle cells (HASMCs). Functional experiments demonstrated that CKLF1 promoted monocyte adhesion and HASMC migration via VCAM-1. These results suggest CKLF1 accelerates NIH by promoting monocyte adhesion and HASMC migration via the NF-κB/VCAM-1 pathway. Our findings contribute to a better understanding of the mechanisms underlying the causality of CKLF1 on NIH and could prove beneficial in designing therapeutic modalities with a focus on CKLF1.

Chemokine-like factor 1: A promising therapeutic target in human diseases.

IMPACT STATEMENT: CKLF1, a recently identified chemokine, has been reported by a number of studies to play important roles in quite many diseases. However, the potential pathways that CKLF1 may be involved are not manifested well yet. In our review, we showed the basic molecular structure and major functions of this novel chemokine, and implication in human diseases, such as tumors. To attract more attention, we summarized its signaling pathways and clearly present them in a set of figures. With the overview of the experimental trial of CKLF1-targeting medicines in animal models, we hope to provide a few important insights about CKLF1 to both medical researchers and pharmacy.

CKLF1 aggravates neointimal hyperplasia by inhibiting apoptosis of vascular smooth muscle cells through PI3K/AKT/NF-κB signaling.

Chemokine-like factor 1 (CKLF1) is a cytokine, which has a detrimental effect on the multiple disease progression. Our previous studies reported that arterial injury induced the upregulation of CKLF1 expression in artery at 7-14 days after injury. Here, using a rat carotid balloon injury model, we found that CKLF1 knockdown in the injured site abolished neointimal formation and even decreased medial area; contrarily, CKLF1 overexpression developed a thicker neointima than controls, demonstrating that CKLF1 exerted positive effects on neointimal hyperplasia and the accumulation of vascular smooth muscle cells (VSMC). The mechanism study indicated that CKLF1 reduced susceptibility to the cell cycle G2/M arrest and apoptosis, and thereby speeding up VSMC accumulation. This role of CKLF1 was tightly associated with phosphatidylinositol (PI) 3-kinase signaling pathway. CKLF1 increased the expression of four isoforms of the PI3-kinase catalytic subunits, which in turn activated its downstream targets Akt and an effector NF-κB accepted as critical transcription factors of cell survival and proliferation. Furthermore, RNA-sequencing analysis revealed that CKLF1 had wide-ranging roles in regulating the expression of genes that mainly engaged in cell apoptosis and innate immune response. Collectively, the data allow us to conclude that high level CKLF1 after artery injury switches the balance of VSMC proliferation and apoptosis through PI3K/AKT/NF-κB signaling and consequently leads to neointimal hyperplasia. The findings shed insight into new treatment strategies to limit restenosis based on CKLF1 as a future target.

IMM-H004 therapy for permanent focal ischemic cerebral injury via CKLF1/CCR4-mediated NLRP3 inflammasome activation.

Chemokine-like factor 1 (CKLF1) is a potential target for ischemic stroke therapy. The NOD-like receptor protein 3 (NLRP3) inflammasome has been postulated to mediate inflammatory responses during ischemic/reperfusion (I/R) injury. The compound IMM-H004 is a novel coumarin derivative that can improve cerebral I/R injury. This study aims to investigate the effects of IMM-H004 on ischemia stroke injury and further elucidate the molecular mechanisms. The standard pMCAO model of focal ischemia was used in this paper. Drugs were administered at 6 hours after ischemia, and behavioral assessment, euthanasia, and outcome measures were evaluated at 9 hours after ischemia. The effects of IMM-H004 on ischemic stroke injury were determined using 2,3,5-triphenyltetrazolium chloride (TTC) staining, behavioral tests, enzyme-linked immunosorbent assay (ELISA), and Nissl staining. Immunohistologic staining, immunofluorescence staining, quantitative RT-PCR (qPCR), western blotting, and coimmunoprecipitation (CO-IP) assays were used to elucidate the underlying mechanisms. IMM-H004 treatment provided significant protection against ischemia stroke through a CKLF1-dependent anti-inflammatory pathway in rats. IMM-H004 downregulated the amount of CKLF1 binding with C-C chemokine receptor type 4, further suppressing the activation of NLRP3 inflammasome and the following inflammatory response, ultimately protecting the ischemic brain. This preclinical study established the efficacy of IMM-H004 as a potential therapeutic medicine for permanent cerebral ischemia. These results support further efforts to develop IMM-H004 for human clinical trials in acute cerebral ischemia, particularly for patients who are not suitable for reperfusion therapy.

Progress in pharmacological research of chemokine like factor 1 (CKLF1).

Currently, the research of chemokines has penetrated into many fields of life science. A new kind of chemokines, chemokine like factor 1 (CKLF1), which is cloned through suppression subtractive hybridisation (SSH) technology is expressed widely in human body, especially in the lung and peripheral blood leukocytes. CKLF1 has a broad spectrum of chemotaxic activity for many cells, such as lymphocytes, macrophages, bone marrow cells, nerve cells and so on. In addition, CKLF1 also stimulates the regeneration of skeletal muscle cells in vivo. Collecting data derived from our and other laboratories show that CKLF1 has an important relationship with allergic diseases, autoimmune diseases, tumors, cardio-cerebrovascular diseases and so on. Therefore, there be an important theoretical purport and applied value to make a summary of pharmacological progress of CKLF1.

Inhibition of chemokine-like factor 1 improves blood-brain barrier dysfunction in rats following focal cerebral ischemia.

Disruption of blood-brain barrier (BBB) and subsequent edema are major contributors to the pathogenesis of ischemic stroke, and the current clinical therapy remains unsatisfied. Chemokine-like factor 1 (CKLF1), as a novel C-C chemokine, plays important roles in immune response. The expression of CKLF1 increased after focal cerebral ischemia and inhibition of CKLF1 activity showed neuroprotective effect by alleviating infiltration of neutrophil and neuron apoptosis in cerebral ischemia. However, few studies have focused on the role of CKLF1 on BBB integrity. The objective of present study was to investigate the role of CKLF1 on BBB integrity by applying anti-CKLF1 antibodies in rat focal cerebral ischemia and reperfusion model. Brain water content, Evans blue leakage and the expression of aquaporin-4 (AQP-4), matrix metalloproteinase-9 (MMP-9), Zonula Occludens-1 (ZO-1) and Occludin were measured. After treatment with anti-CKLF1 antibody, brain water content and Evans blue leakage in ipsilateral hemisphere were decreased in a dose-dependent manner at 24h after reperfusion, but not changed in contralateral hemisphere. Anti-CKLF1 antibody reduced the expression of AQP-4 and MMP-9, and upregulated the expression of ZO-1 and Occludin. These results suggest that CKLF1 is involved in BBB disruption after reperfusion. Inhibition of CKLF1 protects against cerebral ischemia by maintaining BBB integrity, possibly via inhibiting the expression of AQP-4 and MMP-9, and increasing the expression of tight junction protein.

Distinct expression of chemokine-like factor 1 in synovium of osteoarthritis, rheumatoid arthritis and ankylosing spondylitis.

Chemokine-like factor 1 (CKLF1) is a newly cloned chemotactic cytokine with CCR4 being its functional receptor. Recent evidence demonstrates a role of CKLF1 in arthritis. The aim of this study was to quantify the expression of CKLF1 as well as assess the correlation between CKLF1 and plasma acute-phase markers. Synovium was obtained from 16 osteoarthritis (OA), 15 rheumatoid arthritis (RA) and 10 ankylosing spondylitis (AS) patients undergoing total joint arthroplasty, with other 11 patients treated for meniscal tears during sport accidents serving as normal controls. Levels of CKLF1 and CCR4 mRNA were detected by qRT-PCR, and the expression of CKLF1 was investigated by immunohistochemistry staining, subsequently analyzed with semiquantitative scores. Plasma acute-phase markers of inflammation were determined by ELISA. CKLF1 was found with a particularly up-regulated expression in synovim from AS and RA patients, and CCR4 mRNA levels increased in RA patients, not in OA or AS patients. Elevated levels of plasma markers of inflammation including CRP, ESR and D-dimer were observed in RA. Further, significantly positive correlations between relative expression levels of CKLF1 and CRP/ESR in RA patients and a positive correlation between CKLF1 and ESR in AS patients were found. There was no detectable correlation between CKLF1 and plasma D-dimer. This study confirms an increased but different level of CKLF1 in RA, OA and AS patients, all significantly higher than that in controls. Additionally, the significant positive correlations between CKLF1 levels and CRP/ESR in RA and between CKLF1 and ESR suggest that CKLF1 might contribute to the inflammation state and clinical symptoms in these rheumatic diseases. Further studies are required to investigate the utility of targeting specific CKLF1 for symptom control or disease modification in RA and AS.

Study of the functional mechanisms of osteopontin and chemokine-like factor 1 in the development and progression of abdominal aortic aneurysms in rats.

The aim of the study was to investigate the functional mechanisms of osteopontin (Opn) and chemokine-like factor 1 (Cklf1) during the development and progression of abdominal aortic aneurysms (AAA) in rats. Healthy adult Sprague-Dawley rats (n=30) were randomly divided into the AAA, control and sham groups (10 rats/group) and experimental rat models of AAA were generated by enzyme perfusion in abdominal aorta for 30 min. The AAA formation was assessed by measuring the aortal diameter and hematoxylin and eosin staining as well as specific staining to detect the structural changes of the aorta and inflammatory cell infiltration. Immunohistochemistry, western blot analysis and statistical analysis were also performed to examine the expression levels of Opn, Cklf1 and matrix metalloproteinase (MMP)-2 in the arterial tissue. Rat models of AAA were successfully established by protease perfusion. After perfusion, the diameter expansion rate of abdominal aorta was significantly higher (P<0.01) compared to controls, elastin present at the middle layer was significantly reduced and inflammatory cell infiltration was significantly higher in AAA rats. The expression of Opn, Cklf1 and MMP-2 in the AAA group was significantly increased compared to the control group (P<0.05) as revealed by immunohistochemical staining. The western blot analysis revealed that, the expression levels of Opn, Cklf1 and MMP-2 in the AAA group were significantly higher than the sham and control groups (P<0.01). We also found that the expression of Opn and MMP-2 was positively correlated. In conclusion, in rat models of AAA, Opn and Cklf1 function synergistically to upregulate the expression of MMP-2, causing accelerated degradation of extracellular matrix and eventually leading to the development and progression of AAA.

Inhibition of chemokine-like factor 1 protects against focal cerebral ischemia through the promotion of energy metabolism and anti-apoptotic effect.

Chemokine-like factor 1 (CKLF1) is a novel C-C chemokine, and plays important roles in immune response and brain development. In previous study, we have found that the expression of CKLF1 increased after focal cerebral ischemia and inhibition of CKLF1 using antagonist C19 peptide protected against cerebral ischemia. However, few studies have focused on the role of CKLF1 on neuronal apoptosis. The objective of present study is to investigate the role of CKLF1 on neuronal apoptosis by applying anti-CKLF1 antibodies in rat focal cerebral ischemia and reperfusion model. Antibodies against CKLF1 was applied to the right cerebral ventricle immediately after transient middle cerebral artery occlusion (MCAO), and infarct volume, neurological score, glucose metabolism and apoptosis-related protein were measured. Treatment with anti-CKLF1 antibody decreased infarct volume and neurological score, and inhibited neuronal apoptosis in a dose-dependent manner at 24h after reperfusion. Anti-CKLF1 antibody also reduced the level of phosphorylation of Akt (P-Akt), and led to decrease of pro-apoptotic protein Bcl-2 associated X protein (Bax) and increase of anti-apoptotic protein B cell lymphoma-2 protein (Bcl-2) and the ratio of Bcl-2/Bax, and inhibited caspase-3 at last. In addition, positron emission tomography (PET) indicated that anti-CKLF1 antibody increased glucose metabolism in ischemic hemisphere. These results suggest that CKLF1 is associated with neuronal apoptosis after cerebral ischemia and reperfusion. Neutralization of CKLF1 with antibodies shows neuroprotective effects against cerebral ischemia, which may be involved in inhibition of Akt pathway, regulation of apoptosis-related protein expression, and improvement glucose metabolism in ischemic hemisphere. Therefore, CKLF1 may be a novel target for the treatment of stroke.

The chemokine-like factor 1 induces asthmatic pathological change by activating nuclear factor-κB signaling pathway.

CKLF1, which exhibits chemotactic activities on a wide spectrum of leukocytes, is up-regulated during the progress of asthma. It plays a vital role in the pathogenesis of pulmonary disease. Here, we report that CKLF1 has the capability to activate the NF-κB signaling pathway leading to the pathological change in the lung. The HEK293-CCR4 cell line, which expressed CCR4 stably, was established and screened. Western blot analysis was performed to determine the expression of NF-κB in HEK293-CCR4 and A549 cells following the C27 (10µg/ml) added in each well at different times. These results showed that C27 (10µg/ml) time-dependently induced the accumulation of NF-κB in the nucleus of HEK293-CCR4 and A549 cells. In addition, CKLF1 plasmid (100µg) injection and electroporation led to the asthmatic change in the lung in mice as shown by HE and PAS staining. Furthermore, it was confirmed that CKLF1 significantly up-regulated the p-IκB expression, decreased the IκB expression, and suppressed the NF-κB expression in the cytoplasm of pulmonary tissue in vivo study. Intriguingly, an enhanced nuclear accumulation of NF-κB was observed in the lung of pCDI-CKLF1 electroporated mice, compared to that in the sham group. Therefore, the NF-κB signaling pathway was involved in the asthmatic change induced by CKLF1, among which CCR4 might play a crucial role.

Targeted reduction of CCR4⁺ cells is sufficient to suppress allergic airway inflammation.

BACKGROUND: Bronchial asthma is characterized by allergic airway inflammation involving C-C chemokine receptor type 4 (CCR4)-positive Th2 cells. As such, we hypothesize that the disease can be alleviated by targeted-elimination of CCR4⁺ cells. Thymus and activation-regulated chemokine (TARC)-PE38, a TARC fused the exotoxin fragment PE38 from Pseudomonas aeruginosa, has been shown to efficiently kill CCR4⁺ cells by delivering the exotoxin fragment PE38 into CCR4⁺ cells. To test our hypothesis, we examined whether TARC-PE38 could suppress allergic airway inflammation in a mouse model of house dust mite (HDM)-induced allergic airway inflammation. METHODS: We evaluated the effect of TARC-PE38 on the major characteristics of HDM-induced allergic airway inflammation. Airway hyperresponsiveness, lung histopathology, lung Th1/Th2 cell populations, and concentrations of Th1/Th2 cytokines in the lungs were assessed in HDM-sensitized and challenged mice in the presence and absence of TARC-PE38. RESULTS: TARC-PE38 efficiently suppressed allergic airway inflammation by significantly reducing airway hyperresponsiveness, the overall area of inflammation, and goblet cell hyperplasia. In HDM-sensitized and challenged mice, TARC-PE38 specifically reduced the numbers of CCR4⁺ cells. This reduction was associated with a significant decrease in the production of Th2 cytokines in the airway,and a decrease in the number of leukocytes, including macrophages, eosinophils and lymphocytes, within the subepithelial area of the lungs and airway lumen. TARC-PE38 had noeffect on Th1 cells. CONCLUSION: Our data suggest that the elimination of CCR4⁺ cells via TARC-PE38 treatment is sufficient to control allergic airway inflammation and airway hyperresponsiveness.

Chemokine-like factor 1 (CLFK1) is over-expressed in patients with atopic dermatitis.

BACKGROUND: Human chemokine-like factor 1 (CKLF1), a recently discovered chemokine, has a broad spectrum of biological functions in immune-mediated diseases. It is highly expressed on Th2 lymphocytes and is a functional ligand for human CCR4. CKLF1 has a major role in the recruitment and activation of leucocytes, which plays an important role in the pathogenesis of allergic diseases. The present study was designed to determine the expression of CKLF1 in skin and serum in patients with atopic dermatitis (AD). METHODS: The CKLF1 protein expression in skin lesion was analyzed by immunohistochemistry and ELISA. The mRNA expression of CKLF1 in skin lesion was detected by Real-time PCR. The serum levels of CKLF1, IgE, eotaxin, IL-4, IL-5, and IL-13 were measured by ELISA. RESULTS: Histopathological changes in the skin of AD patients showed local inflammation with epidermal thickening and significant inflammatory cellular infiltration. Immunohistochemistry results demonstrated that CKLF1-staining positive cells were located in the epidermal and dermis, and that the CKLF1 expression in AD patients was significantly higher than that in normal control. The CKLF1 mRNA expression in AD patients was significantly higher than that in healthy controls. Serum CKLF1 and IgE levels were significantly increased in AD patients, as were the serum levels of IL-4, IL-5, IL-13 and eotaxin. CONCLUSIONS: Both CKLF1 protien and mRNA levels are overexpressed in the skin lesion of AD patients, along with an increase in serum CKLF1 level, indicating that CKLF1 may play an important role in the development of atopic dermatitis.