Extracellular cyclophilins contribute to the regulation of inflammatory responses

Immunoregulatory cyclophilin a improves low-dose chemotherapy with a modulation of the immune tumor microenvironment in experimental models of melanoma B16 and lymphoma EL4 in vivo

PURPOSE

Different regimens of low-dose chemotherapy (LDC) are currently being actively developed and introduced into clinical practice. Along with its obvious advantages compared to conventional chemotherapy (low toxicity, prevention of drug resistance), LDC could also stimulate anti-tumor immune responses in a patient by activating effectors of innate and adaptive immunity and diminishing tumor-associated immunosuppression. As non-myeloablative, LDC could be successfully combined with different anti-cancer immunotherapeutic strategies, including immunoregulatory cytokines. Secreted cyclophilin A (CypA) is of particular interest in this respect. Previously, we showed that recombinant human CypA (rhCypA) had pleiotropic immunostimulatory activity and anti-tumor effects. Thus, rhCypA could be potentially proposed as a perspective component of combined therapy with LDC.

METHODS

In this work, we evaluated the anti-tumor effects of rhCypA combined with low doses of cyclophosphamide, doxorubicin, dacarbazine, and paclitaxel in the experimental mouse tumor models of melanoma B16 and lymphoma EL4 in vivo.

RESULTS

Synergic and potentiating effects of rhCypA combined with LDC were shown in these studies. Furthermore, as a monotherapeutic agent and a component of combined chemoimmunotherapy, rhCypA was shown to modulate the immune tumor microenvironment by enhancing tumor infiltration with macrophages, NK cells, and T cells. It was also found that rhCypA stimulated both systemic and local anti-tumor immune responses.

CONCLUSION

RhCypA could be potentially proposed as a perspective component of the combined cancer chemoimmunotherapy.

The extracellular cyclophilin A-integrin β2 complex as a therapeutic target of viral pneumonia

The acute respiratory virus infection can induce uncontrolled inflammatory responses, such as cytokine storm and viral pneumonia, which are the major causes of death in clinical cases. Cyclophilin A (CypA) is mainly distributed in the cytoplasm of resting cells and released into the extracellular space in response to inflammatory stimuli. Extracellular CypA (eCypA) is upregulated and promotes inflammatory response in severe COVID-19 patients. However, how eCypA promotes virus-induced inflammatory response remains elusive. Here, we observe that eCypA is induced by influenza A and B viruses and SARS-CoV-2 in cells, mice, or patients. Anti-CypA mAb reduces pro-inflammatory cytokines production, leukocytes infiltration, and lung injury in virus-infected mice. Mechanistically, eCypA binding to integrin β2 triggers integrin activation, thereby facilitating leukocyte trafficking and cytokines production via the focal adhesion kinase (FAK)/GTPase and FAK/ERK/P65 pathways, respectively. These functions are suppressed by the anti-CypA mAb that specifically blocks eCypA-integrin β2 interaction. Overall, our findings reveal that eCypA-integrin β2 signaling mediates virus-induced inflammatory response, indicating that eCypA is a potential target for antibody therapy against viral pneumonia.

Inhibitors of Cyclophilin A: Current and Anticipated Pharmaceutical Agents for Inflammatory Diseases and Cancers

Cyclophilin A, a widely prevalent cellular protein, exhibits peptidyl-prolyl cis-trans isomerase activity. This protein is predominantly located in the cytosol; additionally, it can be secreted by the cells in response to inflammatory stimuli. Cyclophilin A has been identified to be a key player in many of the biological events and is therefore involved in several diseases, including vascular and inflammatory diseases, immune disorders, aging, and cancers. It represents an attractive target for therapeutic intervention with small molecule inhibitors such as cyclosporin A. Recently, a number of novel inhibitors of cyclophilin A have emerged. However, it remains elusive whether and how many cyclophilin A inhibitors function in the inflammatory diseases and cancers. In this review, we discuss current available data about cyclophilin A inhibitors, including cyclosporin A and its derivatives, quinoxaline derivatives, and peptide analogues, and outline the most recent advances in clinical trials of these agents. Inhibitors of cyclophilin A are poised to enhance our comprehension of the molecular mechanisms that underpin inflammatory diseases and cancers associated with cyclophilin A. This advancement will aid in the development of innovative pharmaceutical treatments in the future.

Targeting cancer-derived extracellular vesicles by combining CD147 inhibition with tissue factor pathway inhibitor for the management of urothelial cancer cells

BACKGROUND

Extracellular vesicles (EVs), including microvesicles, hold promise for the management of bladder urothelial carcinoma (BLCA), particularly because of their utility in identifying therapeutic targets and their diagnostic potential using easily accessible urine samples. Among the transmembrane glycoproteins highly enriched in cancer-derived EVs, tissue factor (TF) and CD147 have been implicated in promoting tumor progression. In this in vitro study, we explored a novel approach to impede cancer cell migration and metastasis by simultaneously targeting these molecules on urothelial cancer-derived EVs.

METHODS

Cell culture supernatants from invasive and non-invasive bladder cancer cell lines and urine samples from patients with BLCA were collected. Large, microvesicle-like EVs were isolated using sequential centrifugation and characterized by electron microscopy, nanoparticle tracking analysis, and flow cytometry. The impact of urinary or cell supernatant-derived EVs on cellular phenotypes was evaluated using cell-based assays following combined treatment with a specific CD147 inhibitor alone or in combination with a tissue factor pathway inhibitor (TFPI), an endogenous anticoagulant protein that can be released by low-molecular-weight heparins.

RESULTS

We observed that EVs obtained from the urine samples of patients with muscle-invasive BLCA and from the aggressive bladder cancer cell line J82 exhibited higher TF activity and CD147 expression levels than did their non-invasive counterparts. The shedding of GFP-tagged CD147 into isolated vesicles demonstrated that the vesicles originated from plasma cell membranes. EVs originating from invasive cancer cells were found to trigger migration, secretion of matrix metalloproteinases (MMPs), and invasion. The same induction of MMP activity was replicated using EVs obtained from urine samples of patients with invasive BLCA. EVs derived from cancer cell clones overexpressing TF and CD147 were produced in higher quantities and exhibited a higher invasive potential than those from control cancer cells. TFPI interfered with the effect when used in conjunction with the CD147 inhibitor, further suppressing homotypic EV-induced migration, MMP production, and invasion.

CONCLUSIONS

Our findings suggest that combining a CD147 inhibitor with low molecular weight heparins to induce TFPI release may be a promising therapeutic approach for urothelial cancer management. This combination can potentially suppress the tumor-promoting actions of cancer-derived microvesicle-like EVs, including collective matrix invasion.

Pharmacokinetic Parameters of Recombinant Human Cyclophilin A in Mice

BACKGROUND AND OBJECTIVE

Cyclophilin A (CypA) is an isomerase that functions as a chaperone, housekeeping protein, and cyclosporine A (CsA) ligand. Secreted CypA is a proinflammatory factor, chemoattractant, immune regulator, and factor of antitumor immunity. Experimental data suggest clinical applications of recombinant human CypA (rhCypA) as a biotherapeutic for cancer immunotherapy, stimulation of tissue regeneration, treatment of brain pathologies, and as a supportive treatment for CsA-based therapies. The objective of this study is to analyze the pharmacokinetics of rhCypA in a mouse model.

METHODS

rhCypA was isotope-labeled with 125I and injected intraperitoneally (i.p.) or subcutaneously (s/c) into female mice as a single dose of 100 μg per mouse, equivalent to the estimated first-in-human dose. Analysis of 125I-rhCypA biodistribution and excretion was performed by direct radiometry of the blood, viscera, and urine of mice 0.5-72 h following its administration.

RESULTS

rhCypA showed rapid and even tissue-organ distribution, with the highest tropism (fT = 1.56) and accumulation (maximum concentration, Cmax = 137-167 μg/g) in the kidneys, its primary excretory organ. rhCypA showed the lowest tropism to the bone marrow and the brain (fT = 0.07) but the longest retention in these organs [mean retention time (MRT) = 25-28 h].

CONCLUSION

This study identified promising target organs for rhCypA's potential therapeutic effects. The mode of rhCypA accumulation and retention in organs could be primarily due to the expression of its receptors in them. For the first time, rhCypA was shown to cross the blood-brain barrier and accumulate in the brain. These rhCypA pharmacokinetic data could be extrapolated to humans as preliminary data for possible clinical trials.

Secreted cyclophilin A is non-genotoxic but acts as a tumor promoter

Chronic inflammation is associated with malignant transformation and creates the microenvironment for tumor progression. Cyclophilin A (CypA) is one of the major pro-inflammatory mediators that accumulates and persists in the site of inflammation in high doses over time. According to multiomics analyses of transformed cells, CypA is widely recognized as a pro-oncogenic factor. Vast experimental data define the functions of intracellular CypA in carcinogenesis, but findings on the role of its secreted form in tumor formation and progression are scarce. In the studies here, we exploit short-term in vitro and in vivo tests to directly evaluate the mutagenic, recombinogenic, and blastomogenic effects, as well as the promoter activity of recombinant human CypA (rhCypA), an analogue of secreted CypA. Our findings showed that rhCypA had no genotoxicity and, thus, was neither involved in nor influenced the initiation stage of carcinogenesis. At high doses, rhCypA could disrupt gap junctions in rat liver epithelial IAR-2 cells in vitro by decreasing the expression of connexins 26 and 43 in these cells and inhibit A549 cell adhesion. These data suggested that rhCypA could contribute to epithelial-mesenchymal transition in malignant cells. The research presented here elucidated the role of secreted CypA in carcinogenesis, revealing that it is not a tumor initiator but can act as a tumor promoter at high concentrations.

PROTAC targeting cyclophilin A controls virus-induced cytokine storm

Cytokine storms caused by viruses are associated with elevated cytokine levels and uncontrolled inflammatory responses that can lead to acute respiratory distress syndrome. Current antiviral therapies are not sufficient to prevent or treat these complications. Cyclophilin A (CypA) is a key factor that regulates the production of multiple cytokines and could be a potential therapeutic target for cytokine storms. Here, three proteolysis targeting chimeras (PROTACs) targeting CypA were designed. These PROTACs bind to CypA, enhance its ubiquitination, and promote its degradation in both cell lines and mouse organs. During influenza B virus (IBV) infection, PROTAC-mediated CypA depletion reduces P65 phosphorylation and NF-κB-mediated proinflammatory cytokine production in A549 cells. Moreover, Comp-K targeting CypA suppresses excessive secretion of proinflammatory cytokines in bronchoalveolar lavage fluid, reduces lung injury, and enhances survival rates of IBV-infected mice. Collectively, we provide PROTACs targeting CypA, which are potential candidates for the control of cytokine storms.

Cyclophilin A as a Pro-Inflammatory Factor Exhibits Embryotoxic and Teratogenic Effects during Fetal Organogenesis

The precise balance of Th1, Th2, and Th17 cytokines is a key factor in successful pregnancy and normal embryonic development. However, to date, not all humoral factors that regulate and influence physiological pregnancy have been completely studied. Our data here pointed out cyclophilin A (CypA) as the adverse pro-inflammatory factor negatively affecting fetal development and associated with pregnancy complications. In different mouse models in vivo, we demonstrated dramatic embryotoxicity and teratogenicity of increased CypA levels during pregnancy. Using generated transgenic models, we showed that CypA overexpression in fetal tissues induced the death of all transgenic fetuses and complete miscarriage. Administration of recombinant human CypA in a high dose to pregnant females during fetal organogenesis (6.5-11.5 dpc) exhibited teratogenic effects, causing severe defects in the brain and bone development that could lead to malformations and postnatal behavioral and cognitive disorders in the offspring. Embryotoxic and teratogenic effects could be mediated by CypA-induced up-regulation of M1 macrophage polarization via activation of the STAT1/3 signaling pathways. Here, we propose secreted CypA as a novel marker of complicated pregnancy and a therapeutic target for the correction of pregnancy complications.

Inhibitor of CD147 Suppresses T Cell Activation and Recruitment in CVB3-Induced Acute Viral Myocarditis

Viral myocarditis (VMC) is a common disease characterized by cardiac inflammation. AC-73, an inhibitor of CD147, disrupts the dimerization of CD147, which participates in the regulation of inflammation. To explore whether AC-73 could alleviate cardiac inflammation induced by CVB3, mice were injected intraperitoneally with AC-73 on the fourth day post-infection (dpi) and sacrificed on the seventh dpi. Pathological changes in the myocardium, T cell activation or differentiation, and expression of cytokines were analyzed using H&E staining, flow cytometry, fluorescence staining and multiplex immunoassay. The results showed that AC-73 alleviated cardiac pathological injury and downregulated the percentage of CD45⁺CD3⁺ T cells in the CVB3-infected mice. The administration of AC-73 reduced the percentage of activated CD4⁺ and CD8⁺ T cells (CD69⁺ and/or CD38⁺) in the spleen, while the percentage of CD4⁺ T cell subsets in the spleen was not changed in the CVB3-infected mice. In addition, the infiltration of activated T cells (CD69⁺) and macrophages (F4/80⁺) in the myocardium also decreased after the AC-73 treatment. The results also showed that AC-73 inhibited the release of many cytokines and chemokines in the plasma of the CVB3-infected mice. In conclusion, AC-73 mitigated CVB3-induced myocarditis by inhibiting the activation of T cells and the recruitment of immune cells to the heart. Thus, CD147 may be a therapeutic target for virus-induced cardiac inflammation.

Recognition between CD147 and cyclophilin A deciphered by accelerated molecular dynamics simulations

CD147 functions as the receptor of extracellular cyclophilin A (CypA) in various diseases, and CD147-CypA binding ulteriorly underlies the pathological process of various viral infections including HIV-1, SARS, and SARS-CoV-2. Although CyPA has been identified as a key intermediate pro-inflammatory factor, the mechanism by which CD147 cooperates with CypA in the development of the cytokine storm remains largely unknown, and the binding profile of CD147 with CypA remains to be elucidated as well. Here, we prepared three binding models of the CD147-CypA complex, including the active site of CypA severally binding to the groove bound by the Ig1 and Ig2 domains (model-0), P180-G181 (model-1), and P211 (model-2) of CD147, as well as introducing mutations P180A-G181A and P211A individually in each model. All systems were studied using accelerated molecular dynamics simulations and the molecular mechanics generalized Born surface area (MM/GBSA) method. For model-0, CypA bound to the ectodomain of CD147 with the highest binding affinity. Moreover, mutations P180A-G181A of CD147 in model-0 decreased the binding affinity and weakened the dynamic correlation between CD147 and CypA, which resulted in CypA shifting from the initial binding location. Other residue mutations of CD147 did not significantly affect the CD147-CypA binding, as reflected by the energy and structural analyses. Compared with surface plasmon resonance results and nuclear magnetic resonance shift signals, CypA should tend to reciprocally bind to the groove of CD147, and the binding process might be modulated by P180-G181 rather than P211. Besides, residue R201 of CD147 is critical for CD147-CypA binding and needs further experimental verification. These findings further our understanding of the recruitment between CD147 and CypA and its potential role in the development of inflammation and viral infection.

Lipid-induced monokine cyclophilin-A promotes adipose tissue dysfunction implementing insulin resistance and type 2 diabetes in zebrafish and mice models of obesity

Several studies have implicated obesity-induced macrophage-adipocyte cross-talk in adipose tissue dysfunction and insulin resistance. However, the molecular cues involved in the cross-talk of macrophage and adipocyte causing insulin resistance are currently unknown. Here, we found that a lipid-induced monokine cyclophilin-A (CyPA) significantly attenuates adipocyte functions and insulin sensitivity. Targeted inhibition of CyPA in diet-induced obese zebrafish notably reduced adipose tissue inflammation and restored adipocyte function resulting in improvement of insulin sensitivity. Silencing of macrophage CyPA or pharmacological inhibition of CyPA by TMN355 effectively restored adipocytes' functions and insulin sensitivity. Interestingly, CyPA incubation markedly increased adipocyte inflammation along with an impairment of adipogenesis, however, mutation of its cognate receptor CD147 at P309A and G310A significantly waived CyPA's effect on adipocyte inflammation and its differentiation. Mechanistically, CyPA-CD147 interaction activates NF-κB signaling which promotes adipocyte inflammation by upregulating various pro-inflammatory cytokines gene expression and attenuates adipocyte differentiation by inhibiting PPARγ and C/EBPβ expression via LZTS2-mediated downregulation of β-catenin. Moreover, inhibition of CyPA or its receptor CD147 notably restored palmitate or CyPA-induced adipose tissue dysfunctions and insulin sensitivity. All these results indicate that obesity-induced macrophage-adipocyte cross-talk involving CyPA-CD147 could be a novel target for the management of insulin resistance and type 2 diabetes.

Preparative Production and Purification of Recombinant Human Cyclophilin A

In this work, we developed the method of preparative production of recombinant human cyclophilin A (rhCypA) in Escherichia coli. The full-length cDNA encoding the gene of human CypA (CYPA) was amplified by RT-PCR from the total RNA of human T cell lymphoma Jurkat. The nucleotide sequence of CYPA was optimized to provide highly effective translation in E. coli. Recombinant CYPA DNA was cloned into the pET22b(+) vector, and the resulted expression plasmid was used to transform E. coli strain BL21(DE3)Gold. The recombinant producer strain of E. coli produced soluble rhCypA in the bacterial cytoplasm. The synthesis efficiency of rhCypA was up to 50% of the total cell protein allowing to produce rhCypA in the amount of 1 g per liter of the culture. We also developed the method for rhCypA purification, consisting of a single-step tandem anion exchange chromatography on DEAE- and Q-Sepharose columns. The protein purity was 95% according to electrophoresis (SDS-PAGE), and its contamination with endotoxin did not exceed 0.05 ng per 1 mg of the protein that met the requirements of European pharmacopoeia for injectable preparations. The produced recombinant protein exhibited functional features of native CypA, i.e., isomerase activity and chemokine activity as assessed by stimulation of migration of mouse bone marrow hematopoietic stem cells in vivo. The generated producer strain of E. coli is a super-producer and could be used for large-scale experimental studies of rhCypA and in its preclinical and clinical trials as a drug.

Cyclosporine A Inhibits Viral Infection and Release as Well as Cytokine Production in Lung Cells by Three SARS-CoV-2 Variants

In December 2019, a new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) started spreading worldwide causing the coronavirus disease 2019 (COVID-19) pandemic. The hyperactivation of the immune system has been proposed to account for disease severity and death in COVID-19 patients. Despite several approaches having been tested, no therapeutic protocol has been approved. Given that Cyclosporine A (CsA) is well-known to exert a strong antiviral activity on several viral strains and an anti-inflammatory role in different organs with relevant benefits in diverse pathological contexts, we tested its effects on SARS-CoV-2 infection of lung cells. We found that treatment with CsA either before or after infection of CaLu3 cells by three SARS-CoV-2 variants: (i) reduces the expression of both viral RNA and proteins in infected cells; (ii) decreases the number of progeny virions released by infected cells; (iii) dampens the virus-triggered synthesis of cytokines (including IL-6, IL-8, IL1α and TNF-α) that are involved in cytokine storm in patients. Altogether, these data provide a rationale for CsA repositioning for the treatment of severe COVID-19 patients.

IMPORTANCE SARS-CoV-2 is the most recently identified member of the betacoronavirus genus responsible for the COVID-19 pandemic. Repurposing of available drugs has been a “quick and dirty” approach to try to reduce mortality and severe symptoms in affected patients initially, and can still represent an undeniable and valuable approach to face COVID-19 as the continuous appearance and rapid diffusion of more “aggressive”/transmissible variants, capable of eluding antibody neutralization, challenges the effectiveness of some anti-SARS-CoV-2 vaccines. Here, we tested a known antiviral and anti-inflammatory drug, Cyclosporine A (CsA), and found that it dampens viral infection and cytokine release from lung cells upon exposure to three different SARS-CoV-2 variants. Knock down of the main intracellular target of CsA, Cyclophilin A, does not phenocopy the drug inhibition of viral infection. Altogether, these findings shed new light on the cellular mechanisms of SARS-CoV-2 infection and provide the rationale for CsA repositioning to treat severe COVID-19 patients.

The Effects of EMMPRIN/CD147 on Late Function and Histopathological Lesions of the Renal Graft

Simple Summary

This study provided innovatory data regarding the role of EMMPRIN in long-term renal graft function and renal biopsy specimens in the form of interstitial fibrosis/tubular atrophy. The main cause of renal fibrosis is identified to be the activation and accumulation of fibroblasts and myofibroblasts in the interstitium, surrounded by increased amounts of extracellular matrix, and EMMPRIN has been proposed as a contributor factor. The study has evidenced that EMMPRIN displays adverse effects on renal graft survival in terms of the frequent occurrence of DGF, poorer short-term and long-term renal graft function, more profound fibrotic lesions in biopsy specimens, and the degree of proteinuria. This represents an opportunity for more accurate prediction of the post-transplant period and early, non-invasive detection of kidney graft dysfunction. Future studies need to further investigate the clinical significance of the presented results.

Abstract

Chronic kidney disease (CKD) is associated with renal fibrosis, and develops with the participation of fibroblasts and myofibroblasts from epithelial-to-mesenchymal transition (EMT). In cancer research, the key role of the glycoprotein CD147/EMMPRIN (extracellular matrix metalloproteinase inducer) in EMT has been proven. In this study, we evaluate how serum CD147/EMMPRIN affects long-term renal graft function and renal biopsy specimen lesions. In total, 49 renal graft recipients who had a renal biopsy within the last 18 months were retrospectively reviewed. At their most recent appointments, their serum concentrations of CD147/EMMPRIN and renal function were assessed. The occurrence of delayed graft function (DGF), estimated glomerular filtration rate (eGFR) at 1-year post-kidney transplantation (Tx) and the subsequent years of the follow-up period, and renal biopsy specimen lesions, mainly those related to renal fibrosis and tubular atrophy, were also evaluated. Results: CD147/EMMPRIN serum concentration correlated negatively with eGFR at the most recent appointment (ME 69 months) and with eGFR at 1 and 2 years after Tx (p < 0.05, R = −0.69, R = −0.39, and R = −0.40, respectively). CD147/EMMPRIN serum levels correlated positively with urine protein concentrations (p < 0.05, R = 0.73). A positive correlation was further found with the severity of renal biopsy specimen lesions such as interstitial fibrosis (CI), tubular atrophy (CT), double contours of the GBM (CG), mesangial matrix expansion (MM), and arteriolar hyalinosis (AH) (p < 0.05, R = 0.39, R = 0.29, R = 0.41, R = 0.32 and R = 0.40, respectively). Patients with a history of DGF had higher CD147/EMMPRIN serum concentrations (<0.05). Conclusions: CD147/EMMPRIN is linked to poorer long-term renal graft function. Additionally, a high serum concentration of CD147/EMMPRIN affects interstitial fibrosis tubular atrophy (IF/TA) lesions and proteinuria.

Cyclophilin A is a key positive and negative feedback regulator within interleukin-6 trans-signaling pathway

Cyclophilin A (CypA), a member of the cyclophilin family, plays a vital role in microorganismal infections, inflammatory diseases, and cancers. Interleukin-6 (IL-6) is a pleiotropic cytokine, exerting variety of effects on inflammation, immune response, hematopoiesis, and tumor proliferation. Binding of IL-6 to soluble IL-6 receptor (sIL-6R) induces pro-inflammatory trans-signaling, which has been described to be stronger than anti-inflammatory classic signaling triggered by the binding of IL-6 to membrane-bound IL-6 receptor. Here we found that upon the treatment of IL-6 and sIL-6R, CypA inhibited the ubiquitination-mediated degradation of IL-6 membrane receptor gp130 and enhanced its dimerization, thereby positively regulated the IL-6 trans-signaling and increased the expression of downstream iNOS, IL-6, and CypA. Furthermore, CypA expression could be negatively regulated by suppressor of cytokine signaling 1 (SOCS1). The SH2 and Box domains of SOCS1 interacted with CypA and promoted its K48-linked ubiquitination-mediated degradation, which inhibited the IL-6 trans-signaling pathway. Collectively, our findings reveal an important role of CypA in the positive and negative feedback regulation of the IL-6 trans-signaling pathway.

Secreted Extracellular Cyclophilin A Is a Novel Mediator of Ventilator-induced Lung Injury

Rationale: Mechanical ventilation is a mainstay of intensive care but contributes to the mortality of patients through ventilator-induced lung injury. eCypA (extracellular CypA [cyclophilin A]) is an emerging inflammatory mediator and metalloproteinase inducer, and the gene responsible for its expression has recently been linked to coronavirus disease (COVID-19). Objectives: To explore the involvement of eCypA in the pathophysiology of ventilator-induced lung injury. Methods: Mice were ventilated with a low or high Vt for up to 3 hours, with or without blockade of eCypA signaling, and lung injury and inflammation were evaluated. Human primary alveolar epithelial cells were exposed to in vitro stretching to explore the cellular source of eCypA, and CypA concentrations were measured in BAL fluid from patients with acute respiratory distress syndrome to evaluate the clinical relevance. Measurements and Main Results: High-Vt ventilation in mice provoked a rapid increase in soluble CypA concentration in the alveolar space but not in plasma. In vivo ventilation and in vitro stretching experiments indicated the alveolar epithelium as the likely major source. In vivo blockade of eCypA signaling substantially attenuated physiological dysfunction, macrophage activation, and MMPs (matrix metalloproteinases). Finally, we found that patients with acute respiratory distress syndrome showed markedly elevated concentrations of eCypA within BAL fluid. Conclusions: CypA is upregulated within the lungs of injuriously ventilated mice (and critically ill patients), where it plays a significant role in lung injury. eCypA represents an exciting novel target for pharmacological intervention.

Cyclophilin A is a factor of antitumor defense in the early stages of tumor development

Cyclophilin A (CypA) is a pro-inflammatory factor with multiple immunomodulating effects. Here, we investigated the effects of recombinant human CypA (rhCypA) as a factor of antitumor host defense. Our results demonstrated that rhCypA dramatically inhibited the growth of murine transplantable tumors (mammary adenocarcinoma Ca755, melanoma B16, Lewis lung carcinoma (LLC), and cervical cancer CC-5). In the B16 model, rhCypA effects were observed only when tumor cells were transplanted at the significantly reduced injection dose, indicating that antitumor properties of rhCypA are more effective at the initial stages of cancer development. Antitumor effect of rhCypA in the CC-5 model was comparable to the action of 5-fluorouracil (5FU), and rhCypA administration prevented 5FU - induced leukopenia in the blood of tumor-bearing mice. In the LLC model, rhCypA injection before but not after tumor resection significantly suppressed the formation of post-surgical metastases. RhCypA exhibited no direct cytotoxic effects in vitro on human leukemia cells (K-562, HL-60, KG-1), indicating that rhCypA antitumor action could be mediated by its immunomodulating activity. In the B16 model, rhCypA had no impact on tumor angiogenesis and gene expression of several MMPs, endogenous CypA, and CD147, which play a crucial role in cancer progression. However, in this model, rhCypA stimulated gene expression of MMPs 8, 9, and 12 that could contribute to malignancy growth inhibition. Here, our findings pointed out CypA as one of the factors of antitumor host defense that can effectively control the initial stages of tumor and metastases formation by regulating the action of MMPs and changing the tumor microenvironment.

Cyclophilins A, B, and C Role in Human T Lymphocytes Upon Inflammatory Conditions

Cyclophilins (Cyps) are a group of peptidyl-prolyl cis/trans isomerases that play crucial roles in regulatory mechanisms of cellular physiology and pathology in several inflammatory conditions. Their receptor, CD147, also participates in the development and progression of the inflammatory response. Nevertheless, the main function of Cyps and their receptor are yet to be deciphered. The release of CypA and the expression of the CD147 receptor in activated T lymphocytes were already described, however, no data are available about other Cyps in these cells. Therefore, in the present work intra and extracellular CypA, B and C levels were measured followed by induced inflammatory conditions. After activation of T lymphocytes by incubation with concanavalin A, both intra and extracellular Cyps levels and the CD147 membrane receptor expression were increased leading to cell migration towards circulating CypA and CypB as chemoattractants. When CypA was modulated by natural and synthetic compounds, the inflammatory cascade was avoided including T cell migration. Our results strengthen the relationship between CypA, B, and C, their receptor, and the inflammatory process in human T lymphocytes, associating CypC with these cells for the first time.

Crosstalk between cyclophilins and T lymphocytes in coronary artery disease

Cardiovascular diseases and atherosclerosis are currently some of the most widespread diseases of our time. Within cardiovascular disease, coronary artery disease and underlying atherosclerosis were recently linked with systemic and local inflammation. Cyclophilins participate in the initiation and progression of these inflammatory-related diseases. Cyclophilins are released into the extracellular space upon inflammatory stimuli and participate in the pathology of cardiovascular diseases. The cell surface receptor for extracellular cyclophilins, the CD147 receptor, also contributes to coronary artery disease pathogenesis. Nevertheless, the physiological relevance of cyclophilin's family and their receptor in cardiovascular diseases remains unclear. The present study aimed to better understand the role of cyclophilins in cardiovascular artery disease and their relationship with inflammation. Hence, cyclophilins and pro-inflammatory interleukins were measured in the serum of 30 subjects (divided into three groups according to coronary artery disease status: 10 patients with acute coronary syndrome, 10 patients with chronic coronary artery disease, and 10 control volunteers). In addition, cyclophilin levels and CD147 receptor expression were measured in T lymphocytes purified from these subjects. Cyclophilin A, B, and C, pro-inflammatory interleukins, and CD147 membrane expression were significantly elevated in patients with coronary artery disease.

Identification of Celastrol as a Novel Therapeutic Agent for Pulmonary Arterial Hypertension and Right Ventricular Failure Through Suppression of Bsg (Basigin)/CyPA (Cyclophilin A)

OBJECTIVE

Pulmonary arterial hypertension is characterized by abnormal proliferation of pulmonary artery smooth muscle cells and vascular remodeling, which leads to right ventricular (RV) failure. Bsg (Basigin) is a transmembrane glycoprotein that promotes myofibroblast differentiation, cell proliferation, and matrix metalloproteinase activation. CyPA (cyclophilin A) binds to its receptor Bsg and promotes pulmonary artery smooth muscle cell proliferation and inflammatory cell recruitment. We previously reported that Bsg promotes cardiac fibrosis and failure in the left ventricle in response to pressure-overload in mice. However, the roles of Bsg and CyPA in RV failure remain to be elucidated. Approach and Results: First, we found that protein levels of Bsg and CyPA were upregulated in the heart of hypoxia-induced pulmonary hypertension (PH) in mice and monocrotaline-induced PH in rats. Furthermore, cardiomyocyte-specific Bsg-overexpressing mice showed exacerbated RV hypertrophy, fibrosis, and dysfunction compared with their littermates under chronic hypoxia and pulmonary artery banding. Treatment with celastrol, which we identified as a suppressor of Bsg and CyPA by drug screening, decreased proliferation, reactive oxygen species, and inflammatory cytokines in pulmonary artery smooth muscle cells. Furthermore, celastrol treatment ameliorated RV systolic pressure, hypertrophy, fibrosis, and dysfunction in hypoxia-induced PH in mice and SU5416/hypoxia-induced PH in rats with reduced Bsg, CyPA, and inflammatory cytokines in the hearts and lungs.

CONCLUSIONS

These results indicate that elevated Bsg in pressure-overloaded RV exacerbates RV dysfunction and that celastrol ameliorates RV dysfunction in PH model animals by suppressing Bsg and its ligand CyPA. Thus, celastrol can be a novel drug for PH and RV failure that targets Bsg and CyPA. Graphic Abstract: A graphic abstract is available for this article.

Treatment with a triazole inhibitor of the mitochondrial permeability transition pore fully corrects the pathology of sapje zebrafish lacking dystrophin

High-throughput screening identified isoxazoles as potent but metabolically unstable inhibitors of the mitochondrial permeability transition pore (PTP). Here we have studied the effects of a metabolically stable triazole analog, TR001, which maintains the PTP inhibitory properties with an in vitro potency in the nanomolar range. We show that TR001 leads to recovery of muscle structure and function of sapje zebrafish, a severe model of Duchenne muscular dystrophy (DMD). PTP inhibition fully restores the otherwise defective respiration in vivo, allowing normal development of sapje individuals in spite of lack of dystrophin. About 80 % sapje zebrafish treated with TR001 are alive and normal at 18 days post fertilization (dpf), a point in time when not a single untreated sapje individual survives. Time to 50 % death of treated zebrafish increases from 5 to 28 dpf, a sizeable number of individuals becoming young adults in spite of the persistent lack of dystrophin expression. TR001 improves respiration of myoblasts and myotubes from DMD patients, suggesting that PTP-dependent dysfunction also occurs in the human disease and that mitochondrial therapy of DMD with PTP-inhibiting triazoles is a viable treatment option.

Regulation of the NLRP3 inflammasome with natural products against chemical-induced liver injury

The past decades have witnessed significant progress in understanding the process of sterile inflammation, which is dependent on a cytosolic complex termed the nucleotide-binding oligomerization domain (NOD)-like receptor containing pyrin domain 3 (NLRP3) inflammasome. Activation of NLRP3 inflammasome requires two steps, including the activation of Toll-like receptor (TLR) by its ligands, resulting in transcriptional procytokine and inflammasome component activation, and the assembly and activation of NLRP3 inflammasome triggered by various danger signals, leading to caspase-1 activation, which could subsequently cleave procytokines into their active forms. Metabolic disorders, ischemia and reperfusion, viral infection and chemical insults are common pathogenic factors of liver-related diseases that usually cause tissue damage and cell death, providing numerous danger signals for the activation of NLRP3 inflammasome. Currently, natural products have attracted much attention as potential agents for the prevention and treatment of liver diseases due to their multitargets and nontoxic natures. A great number of natural products have been shown to exhibit beneficial effects on liver injury induced by various chemicals through regulating NLRP3 inflammasome pathways. In this review, the roles of the NLRP3 inflammasome in chemical-induced liver injury (CILI) and natural products that exhibit beneficial effects in CILI through the regulation of inflammasomes were systematically summarized.

CD147 regulates antitumor CD8+ T-cell responses to facilitate tumor-immune escape

Negative regulation of antitumor T-cell-immune responses facilitates tumor-immune escape. Here, we show that deletion of CD147, a type I transmembrane molecule, in T cells, strongly limits in vivo tumor growth of mouse melanoma and lung cancer in a CD8⁺ T-cell-dependent manner. In mouse tumor models, CD147 expression was upregulated on CD8⁺ tumor-infiltrating lymphocytes (TILs), and CD147 was coexpressed with two immune-checkpoint molecules, Tim-3 and PD-1. Mining publicly available gene-profiling data for CD8⁺ TILs in tumor biopsies from metastatic melanoma patients showed a higher level of CD147 expression in exhausted CD8⁺ TILs than in other subsets of CD8⁺ TILs, along with expression of PD-1 and TIM-3. Additionally, CD147 deletion increased the abundance of TILs, cytotoxic effector function of CD8⁺ T cells, and frequency of PD-1⁺ CD8⁺ TILs, and partly reversed the dysfunctional status of PD-1⁺Tim-3⁺CD8⁺ TILs. The cytotoxic transcription factors Runx3 and T-bet mediation enhanced antitumor responses by CD147^-/- CD8⁺ T cells. Moreover, CD147 deletion in T cells increased the frequency of T_RM-like cells and the expression of the T-cell chemokines CXCL9 and CXCL10 in the tumor microenvironment. Analysis of tumor tissue samples from patients with non-small-cell lung cancer showed negative correlations between CD147 expression on CD8⁺ TILs and the abundance of CD8⁺ TILs, histological grade of the tumor tissue samples, and survival of patients with advanced tumors. Altogether, we found a novel function of CD147 as a negative regulator of antitumor responses mediated by CD8⁺ TILs and identified CD147 as a potential target for cancer immunotherapy.

Oral Neutrophils: Underestimated Players in Oral Cancer

The composition of the oral milieu reflects oral health. Saliva provides an environment for multiple microorganisms, and contains soluble factors and immune cells. Neutrophils, which rapidly react on the changes in the microenvironment, are a major immune cell population in saliva and thus may serve as a biomarker for oral pathologies. This review focuses on salivary neutrophils in the oral cavity, their phenotype changes in physiological and pathological conditions, as well as on factors regulating oral neutrophil amount, activation and functionality, with special emphasis on oral cancer and its risk factors.

Cyclophilin A inhibits trophoblast migration and invasion in vitro and vivo through p38/ERK/JNK pathways and causes features of preeclampsia in mice

AIMS

Numerous studies suggest that excessive maternal inflammation and defective extravillous trophoblast (EVT) invasion could contribute to the development of preeclampsia (PE), but the underlying mechanism remains unclear. Some evidence suggests that CyPA is elevated in PE. This research aims to investigate the effect of recombinant human CyPA on trophoblast migration and invasion both in vitro and in vivo.

MATERIALS AND METHODS

We detected the expression and localization of CyPA in human placenta and explored the effects of CyPA on cell migration and invasion on HTR8/SVneo cell. Additionally, the expression levels of matrix metalloproteinase (MMP)-2/9 and molecules in the p38/ERK/JNK signaling pathway were detected. We established a mouse model by injecting pregnant mice with recombinant human CyPA and measured blood pressure, albumin/creatinine ratio, fetal and placenta weight of mice. Moreover, we examined the placental histology and MMP-2/9 and p38/ERK/JNK expression.

KEY FINDINGS

Our results showed that CyPA inhibited the migration and invasion of HTR8/SVneo cells in a dose-dependent manner, decreasing the expression of matrix metalloproteinase (MMP)-2/9 and molecules in the p38/ERK/JNK signaling pathway. Silencing CyPA could reverse the above effects. Moreover, CyPA could induce PE-like features in pregnant mice and disrupt the structure of the mouse placenta by reducing the junctional zone area. CyPA attenuated the trophoblast invasiveness in mice placenta by downregulating MMP-2/9 expression and p38/ERK/JNK pathway activity.

SIGNIFICANCE

We proposed that CyPA could inhibit trophoblast migration and invasion both in vitro and in vivo, which was involved in PE development.

Predictive value of early second trimester maternal serum cyclophilin A concentrations in women complicated with preeclampsia: a preliminary case-control study

OBJECTIVE

To investigate cyclophilin A in early second trimester of pregnancy before the onset of preeclampsia.

METHODS

In this prospective case-control study, 51 pregnant women whose serum were collected and stored and who developed preeclampsia in later follow-up and 41 pregnant women as control group were included.

RESULTS

Maternal serum cyclophilin A levels in the study group who developed preeclampsia in later follow-up were significantly higher than those of normal healthy pregnant women.

CONCLUSION

Cyclophilin A may be a valuable predictor for pregnant women who subsequently develop preeclampsia in their pregnancies.

Analyses of the toxic properties of recombinant human Cyclophilin A in mice

Cyclophilin A (CypA), an 18 kDa multi-functional protein with cis-trans isomerase activity, is both a ligand for cyclosporine A and a proinflammatory factor. CypA is also a chemoattractant for hemopoietic stem cells and progenitors of different lineages, and can mediate regenerative processes in an organism. Accumulated experimental data have suggested there are practical applications for this protein in the treatment of several diseases (i.e. neutralization of cyclosporine A side effects, etc.). However, the range of CypA safe doses as well as its toxic effects remain unknown. The study here investigated the acute toxicity of a single intraperitoneal (IP) or subcutaneous (SC) dosing of recombinant human CypA (rhCypA) in both female and male mice and its effect on gene expression of acute phase proteins (APP) in the female mice after IP treatment. The results showed that toxicity of rhCypA was most evident in female and male mice dosed IP with 750 mg/kg, and manifested as kidney injury and increased granulocyte/lymphocyte ratios in the blood. Enhanced expression of Sаа1 and Sаа2 genes was induced with doses of 0.1-2 mg/mouse of rhCypA. Injection of the maximal dose (750 mg/kg) significantly stimulated expression of all the APP genes studied.

The contribution of cyclophilin A to immune-mediated central nervous system inflammation

Cyclophilin A has multiple known functions in inflammation. Intracellular cyclophilin A modulates T helper 2 response (Th2) and extracellular cyclophilin A functions as a leukocyte chemotactic factor. The contribution of cyclophilin A to central nervous system (CNS) inflammation has not been reported. To test the hypothesis that inhibition of cyclophilin A would ameliorate immune-mediated CNS inflammation, we compared the course and neuroimmunology of experimental allergic encephalomyelitis (EAE) in cyclophilin A knockout mice and wild type littermates. There was a trend towards lower incidence of EAE in cyclophilin A knockout mice, but the clinical course of EAE among animals that manifested clinical signs of EAE was similar in cyclophilin A knockout and wild type littermates. Antigen recall response to myelin oligodendrocyte glycoprotein (MOG) peptide showed that interferon-γ release was lower in cyclophilin A knockout mice. Analysis of CNS inflammatory cells showed that CD3+ T cell infiltration into the CNS was lower in cyclophilin A knockout mice. These results showed that the loss of cyclophilin A results in altered peripheral immune activation and CNS leukocyte infiltration, but these changes did not result in a substantial change in the clinical course of EAE.

CD147 self-regulates matrix metalloproteinase-2 release in gingival fibroblasts after coculturing with U937 monocytic cells

BACKGROUND

Cluster of differentiation 147 (CD147) is a multifunctional glycoprotein that functions as an inducer of matrix metalloproteinase (MMP) expression in fibroblasts. Synergistically enhanced MMP-2 expression was recently observed in the coculture of human gingival fibroblasts (HGFs) and U937 human monocytic cells; however, the responsible mechanisms have not yet been fully established. The aim of this study was to evaluate the release of soluble CD147 in HGFs after coculturing with U937 cells and its functional effect on the enhancement of MMP-2 expression in HGFs.

METHODS

Enzyme-linked immunosorbent assay was used to determine the amount of CD147 protein in media, whereas real-time polymerase chain reaction was performed to evaluate the mRNA levels of CD147 and MMP-2 in HGFs and U937 cells. The enzyme activities of MMP-2 released from cells were examined by zymography. Transwell coculturing and conditioned media treatments were selected to rule out the effect of direct contact of HGFs and U937 cells.

RESULTS

The protein and mRNA expression of CD147 in HGFs were enhanced after transwell coculturing with U937 cells and exposure to U937-conditioned medium. MMP-2 enzyme activities in HGFs were also significantly increased by the coculturing methods. Administration of exogenous CD147 enhanced MMP-2 expression in HGFs, whereas treatment with cyclosporine-A, which inhibited CD147 expression, reduced U937-enhanced MMP-2 expression in HGFs.

CONCLUSIONS

CD147 can interact with fibroblasts to stimulate the expression of MMPs associated with periodontal extracellular matrix degradation. This study has demonstrated that CD147 released from fibroblasts might play a role in monocyte-enhanced MMP-2 expression in HGFs.

Cyclophilin A and matrix metalloproteinase-9: Their relationship, association with, and diagnostic relevance in stable coronary artery disease

Objectives

Data about the circulating levels of cyclophilin A and matrix metalloproteinase-9 in stable coronary artery disease are contradictory. Moreover, their relationship in this disease is not established yet. Thus, this study was designed to assess the relationship between the circulating levels of cyclophilin A and matrix metalloproteinase-9 in coronary artery disease patients with and without type 2 diabetes mellitus (T2DM).

Methods

Serum levels of cyclophilin A, matrix metalloproteinase-9, and high sensitive C-reactive protein (hsCRP) along with fasting blood glucose, glycated hemoglobin, serum lipids, and the anthropometric parameters were measured in 120 participants who were divided equally into four groups (i) normal controls, (ii) T2DM patients, (iii) stable coronary artery disease patients with T2DM, and (iv) stable coronary artery disease patients without T2DM.

Results

Levels of cyclophilin A and matrix metalloproteinase-9 were significantly elevated in sera of coronary artery disease patients with and without T2DM compared to normal controls and T2DM patients. In multiple linear regression models, only cyclophilin A was observed in the final model where it explained the 24.9% variability of matrix metalloproteinase-9. Additionally, high circulating levels of cyclophilin A and matrix metalloproteinase-9 were associated with an increased risk of developing stable coronary artery disease. Finally, the diagnostic efficacy of cyclophilin A and matrix metalloproteinase-9 to discriminate stable coronary artery disease patients with and without T2DM from subjects without coronary artery disease was found to be higher than that of hsCRP.

Conclusion

Serum level of cyclophilin A might be a determinant factor of matrix metalloproteinase-9 level; both may contribute to the pathogenesis of stable coronary artery disease and they appear to be valuable diagnostic biomarkers of stable coronary artery disease with and without T2DM.

Expression of REGγ in atherosclerotic plaques and promotes endothelial cells apoptosis via the cyclophilin A pathway indicates functional implications in atherogenesis

REGγ is a member of the 11S regulatory particles family of proteasome activators and has been shown to promote the degradation of intact cellular proteins in a ubiquitin- and ATP-independent manner in the progression of various diseases. Our previous studies showed that REGγ-proteasome promotes Protein kinase A catalytic subunit α (PKAcα) turnover to modulate Forkhead box protein O1 (FoxO1) cellular activity in vascular endothelial cell migration and angiogenesis. We, therefore, studied the expression and novel functional implications and pathways involving REGγ in atherogenesis. We studied the expression of REGγ in atherosclerotic plaques in the ApoE-/- mouse model. Using immunohistochemistry, we showed that REGγ was highly expressed in these plaques, and the result of RNA-seq in Human umbilical vein endothelial cells (HUVECs), led us to explore and indentify that REGγ significantly promoted cyclophilin A (CyPA) expression, which is a proinflammatory and proapoptotic molecule in atherosclerosis progression. Next, we studied the regulation of REGγ in CyPA expression, and the proapoptotic effect on Endothelial cells (ECs). REGγ promoted CyPA expression via the REGγ-PKA-FoxO1-CyPA axis, and stimulated CyPA-dependent ECs apoptosis in vitro. Our data indicated that REGγ had proapoptotic effects on ECs depends on CyPA pathway in vitro and functional implications in atherogenesis in vivo.

Synovial fluid proteome changes in ACL injury-induced posttraumatic osteoarthritis: Proteomics analysis of porcine knee synovial fluid

Surgical transection of the anterior cruciate ligament (ACL) in the porcine model leads to posttraumatic osteoarthritis if left untreated. However, a recently developed surgical treatment, bridge-enhanced ACL repair, prevents further cartilage damage. Since the synovial fluid bathes all the intrinsic structures of knee, we reasoned that a comparative analysis of synovial fluid protein contents could help to better understand the observed chondroprotective effects of the bridge-enhanced ACL repair. We hypothesized that post-surgical changes in the synovial fluid proteome would be different in the untreated and repaired knees, and those changes would correlate with the degree of cartilage damage. Thirty adolescent Yucatan mini-pigs underwent unilateral ACL transection and were randomly assigned to either no further treatment (ACLT, n = 14) or bridge-enhanced ACL repair (BEAR, n = 16). We used an isotopically labeled high resolution LC MS/MS-based proteomics approach to analyze the protein profile of synovial fluid at 6 and 12 months after ACL transection in untreated and repaired porcine knees. A linear mixed effect model was used to compare the normalized protein abundance levels between the groups at each time point. Bivariate linear regression analyses were used to assess the correlations between the macroscopic cartilage damage (total lesion area) and normalized abundance levels of each of the identified secreted proteins. There were no significant differences in cartilage lesion area or quantitative abundance levels of the secreted proteins between the ACLT and BEAR groups at 6 months. However, by 12 months, greater cartilage damage was seen in the ACLT group compared to the BEAR group (p = 0.005). This damage was accompanied by differences in the abundance levels of secreted proteins, with higher levels of Vitamin K-dependent protein C (p = 0.001), and lower levels of Apolipoprotein A4 (p = 0.021) and Cartilage intermediate layer protein 1 (p = 0.049) in the ACLT group compared to the BEAR group. There were also group differences in the secreted proteins that significantly changed in abundance between 6 and 12 months in ACLT and BEAR knees. Increased concentration of Ig lambda-1 chain C regions and decreased concentration of Hemopexin, Clusterin, Coagulation factor 12 and Cartilage intermediate layer protein 1 were associated with greater cartilage lesion area. In general, ACLT knees had higher concentrations of pro-inflammatory proteins and lower concentrations of anti-inflammatory proteins than BEAR group. In addition, the ACLT group had a lower and declining synovial concentrations of CILP, in contrast to a consistently high abundance of CILP in repaired knees. These differences suggest that the knees treated with bridge-enhanced ACL repair may be maintaining an environment that is more protective of the extracellular matrix, a function which is not seen in the ACLT knees.

Cyclophilin A and CD147 associate with progression of diabetic nephropathy

To find the associations of circulating cyclophilin A (CyP A) and CD147/EMMPRIN with renal outcomes in type 2 diabetes patients and possible pathogenesis involved. Total 131 patients were recruited since 2004. Glycated hemoglobin, blood glucose and urine albumin-creatinine ratio levels at baseline and every 3 months were measured. Plasma CyP A and CD147 were also measured at baseline. Patients were divided into two groups based upon the median level of the baseline plasma CyP A value: < 93.64 ng/mL (group A, n = 65), ≥ 93.64 ng/mL (group B, n = 66). The estimated glomerular filtration rate was calculated at each follow-up visit. Besides, mitochondrial function assay by cellular mitochondrial energy utility was studied when cells were exposed to glucose or exogenous CyP A or both. Multivariate analysis, using median level (93.64) ng/mL as the cut-off value, revealed that circulating CyP A and CD147 levels at baseline were associated with the baseline estimated glomerular filtration rate (eGFR) (p = .042 and p = .001 separately) in cross-sectional analysis. Longitudinally, higher baseline plasma CyP A level was also correlated to a rapid decline in eGFR (p = .016). The results were also significant when using the continuous plasma CyP A level (p = .003). In cells exposed to glucose, results of oxygen consumption rate (OCR) showed a significant reduction in basal respiration, maximal respiration and ATP production. Depressed OCR further occurred when incubated with both of CyP A and glucose. Plasma CyP A and CD147 can serve as indicators of renal disease progression in type 2 diabetes patients.

EMMPRIN-CypA contributes to the inflammatory processes in human periodontitis through infiltrating CD68+ inflammatory cells

Extracellular matrix metalloproteinase inducer (EMMPRIN) and its ligand cyclophilin A (CypA) levels increase in human inflammatory diseases, but EMMPRIN-CypA interactions and cell types expressing EMMPRIN and CypA in the pathogenesis of periodontitis are uncertain. Immunohistochemistry, immunofluorescence and western blotting revealed the level of EMMPRIN, CypA, and CD68 in human periodontitis. Double labelled immunofluorescence colocalized the expression of CD68 and CypA, and CD68 and EMMPRIN. Further investigation of EMMPRIN-CypA interactions and CD68⁺ infiltrating cells was applied using mouse monocyte cell line RAW264.7 in vitro. A higher level of EMMPRIN and CypA staining was detected in human periodontitis, compared with healthy gingiva. Many inflammatory cells, including CD68⁺ cells, infiltrated gingival tissues of human periodontitis. Both EMMPRIN and CypA could be localized in the CD68⁺ infiltrating cells. CypA could induce NF-κB activation by increasing expression of NFκB p-p65 in the nucleus of mouse monocytic cells RAW264.7 in vitro. EMMPRIN-CypA may contribute to the inflammatory processes in human periodontitis through infiltrating CD68⁺ inflammatory cells.

Predictive value of serum cyclophilin A concentrations after acute pancreatitis

BACKGROUND

Cyclophilin A is identified as a biomarker for inflammation. We elucidated prognostic significance of serum cyclophilin A (CypA) concentrations in acute pancreatitis (AP).

METHODS

In this prospective and observational study, serum CypA concentrations were quantified in 210 AP patients and 100 healthy controls. We recorded local complication, in-hospital mortality and organ failure. Disease severity was assessed using the traditional predictors, namely Acute Physiology and Chronic Health Care Evaluation II score, Ranson score, multiple organ dysfunction score and sequential organ failure assessment score.

RESULTS

Serum CypA concentrations were significantly lower in controls than in AP group. CypA concentrations after AP were highly correlated with the traditional predictors and other inflammatory mediators, including blood erythrocyte sedimentation rate, procalcitonin levels, white blood cell count and C-reactive protein levels. Serum CypA emerged as an independent predictor for in-hospital local complication, organ failure and mortality. Under receiver operating characteristic curve, serum CypA possessed similar prognostic ability, as compared to the traditional predictors. Its predictive ability was almost similar to that of procalcitonin levels and significantly exceeded those of the other inflammatory mediators. Also, it significantly improved prognostic performance of the traditional predictors.

CONCLUSIONS

Increased serum CypA concentrations have close relation to the severity, inflammation and prognosis, substantializing CypA as a potential prognostic biomarker of AP.

Extracellular and Intracellular Cyclophilin A, Native and Post-Translationally Modified, Show Diverse and Specific Pathological Roles in Diseases

CypA (cyclophilin A) is a ubiquitous and highly conserved protein with peptidyl prolyl isomerase activity. Because of its highly abundant level in the cytoplasm, most studies have focused on the roles of CypA as an intracellular protein. However, emerging evidence suggests an important role for extracellular CypA in the pathogenesis of several diseases through receptor (CD147 or other)-mediated autocrine and paracrine signaling pathways. In this review, we will discuss the shared and unique pathological roles of extracellular and intracellular CypA in human cardiovascular diseases. In addition, the evolving role of post-translational modifications of CypA in the pathogenesis of disease is discussed. Finally, recent studies with drugs specific for extracellular CypA show its importance in disease pathogenesis in several animal models and make extracellular CypA a new therapeutic target.

A critical epitope in CD147 facilitates memory CD4+ T-cell hyper-activation in rheumatoid arthritis

The abnormal activation of CD4⁺CD45RO⁺ memory T (Tm) cells plays an important role in the pathogenesis of rheumatoid arthritis (RA). Previous studies have shown that CD147 participates in T-cell activation. However, it remains unclear whether CD147 is involved in abnormal Tm-cell activation in RA patients. In this study, we demonstrated that CD147 was predominantly upregulated in Tm cells derived from RA patients. The anti-CD147 mAb 5A12 specifically inhibited Tm-cell activation and proliferation and further restrained osteoclastogenesis. Using a structural-functional approach, we depicted the interface between 5A12 and CD147. This allowed us to identify two critical residues, Lys63 and Asp65, as potential targets for RA treatment, as the double mutation K63A/D65A inhibited Tm-cell activation, mimicking the neutralization by 5A12. This study provides not only a theoretical basis for a "CD147-Tm/Osteoclast-RA chain" for the potential prevention and treatment of RA or other T-cell-mediated autoimmune diseases but also a new target for related drug design and development.

Extracellular Matrix Metalloproteinase Inducer EMMPRIN (CD147) in Cardiovascular Disease

The receptor EMMPRIN is involved in the development and progression of cardiovascular diseases and in the pathogenesis of myocardial infarction. There are several binding partners of EMMPRIN mediating the effects of EMMPRIN in cardiovascular diseases. EMMPRIN interaction with most binding partners leads to disease progression by mediating cytokine or chemokine release, the activation of platelets and monocytes, as well as the formation of monocyte-platelet aggregates (MPAs). EMMPRIN is also involved in atherosclerosis by mediating the infiltration of pro-inflammatory cells. There is also evidence that EMMPRIN controls energy metabolism of cells and that EMMPRIN binding partners modulate intracellular glycosylation and trafficking of EMMPRIN towards the cell membrane. In this review, we systematically discuss these multifaceted roles of EMMPRIN and its interaction partners, such as Cyclophilins, in cardiovascular disease.

Cyclophilin A as a target in the treatment of cytomegalovirus infections

BACKGROUND

Viruses are obligate parasites that depend on the cellular machinery of the host to regenerate and manufacture their proteins. Most antiviral drugs on the market today target viral proteins. However, the more recent strategies involve targeting the host cell proteins or pathways that mediate viral replication. This new approach would be effective for most viruses while minimizing drug resistance and toxicity.

METHODS

Cytomegalovirus replication, latency, and immune response are mediated by the intermediate early protein 2, the main protein that determines the effectiveness of drugs in cytomegalovirus inhibition. This review explains how intermediate early protein 2 can modify the action of cyclosporin A, an immunosuppressive, and antiviral drug. It also links all the pathways mediated by cyclosporin A, cytomegalovirus replication, and its encoded proteins.

RESULTS

Intermediate early protein 2 can influence the cellular cyclophilin A pathway, affecting cyclosporin A as a mediator of viral replication or anti-cytomegalovirus drug.

CONCLUSION

Cyclosporin A has a dual function in cytomegalovirus pathogenesis. It has the immunosuppressive effect that establishes virus replication through the inhibition of T-cell function. It also has an anti-cytomegalovirus effect mediated by intermediate early protein 2. Both of these functions involve cyclophilin A pathway.

Human Cytomegalovirus Encoded miR-US25-1-5p Attenuates CD147/EMMPRIN-Mediated Early Antiviral Response

Cellular receptor-mediated signaling pathways play critical roles during the initial immune response to Human Cytomegalovirus (HCMV) infection. However, the involvement of type-I transmembrane glycoprotein CD147/EMMPRIN (extracellular matrix metalloproteinase inducer) in the antiviral response to HCMV infection is still unknown. Here, we demonstrated the specific knockdown of CD147 significantly decreased HCMV-induced activation of NF-κB and Interferon-beta (IFN-β), which contribute to the cellular antiviral responses. Next, we confirmed that HCMV-encoded miR-US25-1-5p could target the 3′ UTR (Untranslated Region) of CD147 mRNA, and thus facilitate HCMV lytic propagation at a low multiplicity of infection (MOI). The expression and secretion of Cyclophilin A (sCyPA), as a ligand for CD147 and a proinflammatory cytokine, were up-regulated in response to HCMV stimuli. Finally, we confirmed that CD147 mediated HCMV-triggered antiviral signaling via the sCyPA-CD147-ERK (extracellular regulated protein kinases)/NF-κB axis signaling pathway. These findings reveal an important HCMV mechanism for evading antiviral innate immunity through its encoded microRNA by targeting transmembrane glycoprotein CD147, and a potential cause of HCMV inflammatory disorders due to the secretion of proinflammatory cytokine CyPA.

Extracellular Cyclophilin A Augments Platelet-Dependent Thrombosis and Thromboinflammation

Cyclophilin A (CyPA) is involved in the pathophysiology of several inflammatory and cardiovascular diseases. To our knowledge, there is no specific inhibitor targeting extracellular CyPA without affecting other extracellular cyclophilins or intracellular CyPA functions. In this study, we developed an antibody-based inhibitor of extracellular CyPA and analysed its effects in vitro and in vivo. To generate a specific antibody, mice and rats were immunized with a peptide containing the extracellular matrix metalloproteinase inducer binding site and various antibody clones were selected and purified. At first, antibodies were tested for their binding capacity to recombinant CyPA and their functional activity. The clone 8H7-mAb was chosen for further experiments. 8H7-mAb reduced the CyPA-induced migration of inflammatory cells in vitro and in vivo. Furthermore, 8H7-mAb revealed strong antithrombotic effects by inhibiting CyPA-dependent activation of platelets and thrombus formation in vitro and in vivo. Surprisingly, 8H7-mAb did not influence in vivo tail bleeding time or in vitro whole blood coagulation parameters. Our study provides first evidence that antibody-based inhibition of extracellular CyPA inhibits thrombosis and thromboinflammation without affecting blood homeostasis. Thus, 8H7-mAb may be a promising compound for thrombi modulation in inflammatory diseases to prevent organ dysfunction.

A Novel Cyclophilin B Gene in the Red Tide Dinoflagellate Cochlodinium polykrikoides: Molecular Characterizations and Transcriptional Responses to Environmental Stresses

The marine dinoflagellate Cochlodinium polykrikoides is one of the most common ichthyotoxic species that causes harmful algal blooms (HABs), which leads to ecological damage and huge economic loss in aquaculture industries. Cyclophilins (CYPs) belong to the immunophilin superfamily, and they may play a role in the survival mechanisms of the dinoflagellate in stress environments. In the present study, we identified a novel cyclophilin gene from C. polykrikoides and examined physiological and gene transcriptional responses to biocides copper sulphate (CuSO₄) and sodium hypochlorite (NaOCl). The full length of CpCYP was 903 bp, ranging from the dinoflagellate splice leader (DinoSL) sequence to the polyA tail, comprising a 639 bp ORF, a 117 bp 5′-UTR, and a 147 bp 3′-UTR. Motif and phylogenetic comparisons showed that CpCYP was affiliated to group B of CYP. In biocide stressors, cell counts, chlorophyll a, and photosynthetic efficiency (Fv/Fm) of C. polykrikoides were considerably decreased in both exposure time- and dose-dependent manners. In addition, CpCYP gene expression was significantly induced after 24 h exposure to the biocide-treated stress conditions. These results indicate an effect of the biocides on the cell physiology and expression profile of CpCYP, suggesting that the gene may play a role in environmental stress responses.

Cyclophilin inhibitor NIM811 ameliorates experimental allergic encephalomyelitis

Cyclophilins have diverse functions that may affect the course of central nervous system (CNS) inflammatory disorders. Anti-inflammatory and neuroprotective mechanisms may be targeted by inhibition of cyclophilin A-dependent and cyclophilin D-dependent functions, respectively. We tested the effect of cyclophilin inhibition on CNS inflammation by administering N-methyl-4-isoleucine-cyclosporin (NIM811) to mice undergoing experimental allergic encephalomyelitis (EAE). Treatment with NIM811 resulted in significant reduction of EAE clinical severity. Analysis of mitochondrial calcium retention capacity and the course of EAE in cyclophilin D knockout mice indicated that the effect of NIM811 on EAE was not entirely cyclophilin D-dependent. NIM811-treated EAE animals showed reduction in interleukin-2 expression and reduction in CNS inflammatory infiltrates. These results indicate that anti-inflammatory rather than neuroprotective mechanisms associated with cyclophilins are likely involved in the mechanism of NIM811 in EAE.

Cyclophilin B facilitates the replication of Orf virus

BACKGROUND

Viruses interact with host cellular factors to construct a more favourable environment for their efficient replication. Expression of cyclophilin B (CypB), a cellular peptidyl-prolyl cis-trans isomerase (PPIase), was found to be significantly up-regulated. Recently, a number of studies have shown that CypB is important in the replication of several viruses, including Japanese encephalitis virus (JEV), hepatitis C virus (HCV) and human papillomavirus type 16 (HPV 16). However, the function of cellular CypB in ORFV replication has not yet been explored.

METHODS

Suppression subtractive hybridization (SSH) technique was applied to identify genes differentially expressed in the ORFV-infected MDBK cells at an early phase of infection. Cellular CypB was confirmed to be significantly up-regulated by quantitative reverse transcription-PCR (qRT-PCR) analysis and Western blotting. The role of CypB in ORFV infection was further determined using Cyclosporin A (CsA) and RNA interference (RNAi). Effect of CypB gene silencing on ORFV replication by 50% tissue culture infectious dose (TCID₅₀) assay and qRT-PCR detection.

RESULTS

In the present study, CypB was found to be significantly up-regulated in the ORFV-infected MDBK cells at an early phase of infection. Cyclosporin A (CsA) exhibited suppressive effects on ORFV replication through the inhibition of CypB. Silencing of CypB gene inhibited the replication of ORFV in MDBK cells. In conclusion, these data suggest that CypB is critical for the efficient replication of the ORFV genome.

CONCLUSIONS

Cellular CypB was confirmed to be significantly up-regulated in the ORFV-infected MDBK cells at an early phase of infection, which could effectively facilitate the replication of ORFV.

A 2-year Double-Blind RCT Follow-up Study with Fermented Papaya Preparation (FPP) Modulating Key Markers in Middle-Age Subjects with Clustered Neurodegenerative Disease-Risk Factors

In recent years a number of studies have reported the significant relationship between metabolic syndrome and neurodegenerative disease. There is accumulating evidence that the interplay of combined genetic and environmental risk factors (from diet to life style to pollutants) to intrinsic age-related oxi-inflammatory changes may be advocated for to explain the pandemic of neurodegenerative diseases. In recent years a specific Fermented Papaya Preparation (FPP) has been shown to significantly affect a number of redox signalling abnormalities in a variety of chronic diseases and as well in aging mechanisms either on experimental and on clinical ground. The aim of the present study was to evaluate FPP use in impending metabolic disease patients with potentially neurodegenerative disease clustered risk factors. The study population consisted of 90 patients aged 45-65 years old, with impending metabolic syndrome and previously selected as to be ApoE4 genotype negative. By applying a RCT, double-blind method, one group received FPP 4.5 g twice a day (the most common dosage utilized in prior clinical studies) while the other received an oral antioxidant cocktail (trans-resveratrol, selenium, vitamin E, vitamin C). Then, after 21 month treatment period, a selected heavy metal chelator was added at the dosage of 3 g/nocte for the final 3 months study treatment. The parameters tested were: routine tests oxidized LDL-cholesterol, anti-oxidised LDL, Cyclophilin-A (CyPA), plasminogen activator inhibitor-1 and CyPA gene expression. From this study it would appear that FPP, unlike the control antioxidant, significantly decreased oxidized-LDL and near normalizing the anti-Ox-LDL/Ox-LDL ratio (p<0.001) although unaffecting the lipid profile per sè. Moreover, only FPP decreased cyclophilin-A plasma level and plasminogen activator-inhibitor (p<0.01) together with downregulating cyclophilin-A gene expression (p<0.01). Insulin resistance was only mildly improved. Heavy metals gut clearance proved to be effectively enhanced by the chelator (p<0.01) and this was not affected by any of the nutraceuticals, nor it added any further benefit to the biological action of FPP.