Dealing with the family: CD147 interactions with cyclophilins

13C metabolite tracing reveals glutamine and acetate as critical in vivo fuels for CD8 T cells

Infusion of 13C-labeled metabolites provides a gold standard for understanding the metabolic processes used by T cells during immune responses in vivo. Through infusion of 13C-labeled metabolites (glucose, glutamine, and acetate) in Listeria monocytogenes-infected mice, we demonstrate that CD8 T effector (Teff) cells use metabolites for specific pathways during specific phases of activation. Highly proliferative early Teff cells in vivo shunt glucose primarily toward nucleotide synthesis and leverage glutamine anaplerosis in the tricarboxylic acid (TCA) cycle to support adenosine triphosphate and de novo pyrimidine synthesis. In addition, early Teff cells rely on glutamic-oxaloacetic transaminase 1 (Got1)-which regulates de novo aspartate synthesis-for effector cell expansion in vivo. CD8 Teff cells change fuel preference over the course of infection, switching from glutamine- to acetate-dependent TCA cycle metabolism late in infection. This study provides insights into the dynamics of Teff metabolism, illuminating distinct pathways of fuel consumption associated with CD8 Teff cell function in vivo.

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.

Multi-omic analysis characterizes molecular susceptibility of receptors to SARS-CoV-2 spike protein

In the post COVID-19 era, new SARS-CoV-2 variant strains may continue emerging and long COVID is poised to be another public health challenge. Deciphering the molecular susceptibility of receptors to SARS-CoV-2 spike protein is critical for understanding the immune responses in COVID-19 and the rationale of multi-organ injuries. Currently, such systematic exploration remains limited. Here, we conduct multi-omic analysis of protein binding affinities, transcriptomic expressions, and single-cell atlases to characterize the molecular susceptibility of receptors to SARS-CoV-2 spike protein. Initial affinity analysis explains the domination of delta and omicron variants and demonstrates the strongest affinities between BSG (CD147) receptor and most variants. Further transcriptomic data analysis on 4100 experimental samples and single-cell atlases of 1.4 million cells suggest the potential involvement of BSG in multi-organ injuries and long COVID, and explain the high prevalence of COVID-19 in elders as well as the different risks for patients with underlying diseases. Correlation analysis validated moderate associations between BSG and viral RNA abundance in multiple cell types. Moreover, similar patterns were observed in primates and validated in proteomic expressions. Overall, our findings implicate important therapeutic targets for the development of receptor-specific vaccines and drugs for COVID-19.

Cyclophilins modify their profile depending on the organ or tissue in a murine inflammatory model

Inflammation is the leading subjacent cause of many chronic diseases. Despite several studies in the last decades, the molecular mechanism involving its pathophysiology is not fully known. Recently, the implication of cyclophilins in inflammatory-based diseases has been demonstrated. However, the main role of cyclophilins in these processes remains elusive. Hence, a mouse model of systemic inflammation was used to better understand the relationship between cyclophilins and their tissue distribution. To induce inflammation, mice were fed with high-fat diet for 10 weeks. In these conditions, serum levels of interleukins 2 and 6, tumour necrosis factor-α, interferon-ϒ, and the monocyte chemoattractant protein 1 were elevated, evidencing a systemic inflammatory state. Then, in this inflammatory model, cyclophilins and CD147 profiles in the aorta, liver, and kidney were studied. The results demonstrate that, upon inflammatory conditions, cyclophilins A and C expression levels were increased in the aorta. Cyclophilins A and D were augmented in the liver, meanwhile, cyclophilins B and C were diminished. In the kidney, cyclophilins B and C levels were elevated. Furthermore, CD147 receptor was also increased in the aorta, liver, and kidney. In addition, when cyclophilin A was modulated, serum levels of inflammatory mediators were decreased, indicating a reduction in systemic inflammation. Besides, the expression levels of cyclophilin A and CD147 were also reduced in the aorta and liver, when cyclophilin A was modulated. Therefore, these results suggest that each cyclophilin has a different profile depending on the tissue, under inflammatory conditions.

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.

Effect of SARS-CoV-2 infection in pregnancy on CD147, ACE2 and HLA-G expression

INTRODUCTION

Recent studies reported a differential expression of both ACE2 and CD147 in pregnant women associated to SARS-CoV-2 placental infection. The aim of this study is to further investigate the placental SARS-CoV-2 infection and the potential effect on protein expression (ACE2, CD147, HLA-G and CD56).

METHODS

The study was on three subgroups: i) 18 subjects positive for SARS-CoV-2 swab at delivery; ii) 9 subjects that had a positive SARS-CoV-2 swab during pregnancy but resulted negative at delivery; iii) 11 control subjects with physiological pregnancy and with no previous or concomitant SARS-CoV-2 swab positivity. None of the subjects were vaccinated for SARS-CoV-2 infection. The placenta samples were analyzed for SARS-CoV-2 NP (Nucleocapsid protein) positivity and the expression of ACE2, CD147, HLA-G and CD56.

RESULTS

We observed a higher percentage of SARS-CoV-2 NP positive placenta samples in the group of SARS-CoV-2 PCR positive at delivery in comparison with SARS-CoV-2 PCR negative at delivery. The localization of SARS-CoV-2 NP positivity in placenta samples was mainly in syncytiotrophoblast (ST) of SARS-CoV-2 PCR positive at delivery group and in extra-villous trophoblast (EVT) of SARS-CoV-2 PCR negative at delivery group. CD147, HLA-G positivity was higher in ST of SARS-CoV-2 PCR positive at delivery group, while CD56-expressing immune cells were decreased in comparison with control subjects.

DISCUSSION

We confirmed the ability of SARS-CoV-2 to infect placenta tissues. The simultaneous SARS-CoV-2 swab positivity at delivery and the positivity of the placenta tissue for SARS-CoV-2 NP seems to create an environment that modifies the expression of specific molecules, as CD147 and HLA-G. These data suggest a possible impact of SARS-CoV-2 infection during pregnancy, that might be worthy to be monitored also in vaccinated subjects.

CD147 and MMPs as key factors in physiological and pathological processes

Cluster of differentiation 147 (CD147) or extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that induces the synthesis of matrix metalloproteinases (MMPs). MMPs, as zinc-dependent proteases and versatile enzymes, play critical roles in the degradation of the extracellular matrix (ECM) components, cleaving of the receptors of cellular surfaces, signaling molecules, and other precursor proteins, which may lead to attenuation or activation of such targets. CD147 and MMPs play essential roles in physiological and pathological conditions and any disorder in the expression, synthesis, or function of CD147 and MMPs may be associated with various types of disease. In this review, we have focused on the roles of CD147 and MMPs in some major physiological and pathological processes.

SARS-CoV-2 modulates virus receptor expression in placenta and can induce trophoblast fusion, inflammation and endothelial permeability

SARS-CoV-2 is a devastating virus that induces a range of immunopathological mechanisms including cytokine storm, apoptosis, inflammation and complement and coagulation pathway hyperactivation. However, how the infection impacts pregnant mothers is still being worked out due to evidence of vertical transmission of the SARS-CoV-2, and higher incidence of pre-eclampsia, preterm birth, caesarian section, and fetal mortality. In this study, we assessed the levels of the three main receptors of SARS-CoV-2 (ACE2, TMPRSS2 and CD147) in placentae derived from SARS-CoV-2 positive and negative mothers. Moreover, we measured the effects of Spike protein on placental cell lines, in addition to their susceptibility to infection. SARS-CoV-2 negative placentae showed elevated levels of CD147 and considerably low amount of TMPRSS2, making them non-permissive to infection. SARS-CoV-2 presence upregulated TMPRSS2 expression in syncytiotrophoblast and cytotrophoblast cells, thereby rendering them amenable to infection. The non-permissiveness of placental cells can be due to their less fusogenicity due to infection. We also found that Spike protein was capable of inducing pro-inflammatory cytokine production, syncytiotrophoblast apoptosis and increased vascular permeability. These events can elicit pre-eclampsia-like syndrome that marks a high percentage of pregnancies when mothers are infected with SARS-CoV-2. Our study raises important points relevant to SARS-CoV-2 mediated adverse pregnancy outcomes.

Regulatory Role of Apoptotic and Inflammasome Related Proteins and Their Possible Functional Aspect in Thiram Associated Tibial Dyschondroplasia of Poultry

Tibial dyschondroplasia debilities apoptotic and inflammasomal conditions that can further destroy chondrocytes. Inflammasomes are specialized protein complexes that process pro-inflammatory cytokines, e.g., interleukin-1β (IL-1β) and IL-18. Moreover, there is mounting evidence that many of the signaling molecules that govern programmed cell death also affect inflammasome activation in a cell-intrinsic way. During the last decade, apoptotic functions have been described for signaling molecules involving inflammatory responses and cell death pathways. Considering these exceptional developments in the knowledge of processes, this review gives a glimpse of the significance of these two pathways and their connected proteins in tibial dyschondroplasia. The current review deeply elaborates on the elevated level of signaling mediators of mitochondrial-mediated apoptosis and the inflammasome. Although investigating these pathways’ mechanisms has made significant progress, this review identifies areas where more study is especially required. It might lead to developing innovative therapeutics for tibial dyschondroplasia and other associated bone disorders, e.g., osteoporosis and osteoarthritis, where apoptosis and inflammasome are the significant pathways.

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.

Potentiality of Exosomal Proteins as Novel Cancer Biomarkers for Liquid Biopsy

Liquid biopsy has been rapidly developed in recent years due to its advantages of non-invasiveness and real-time sampling in cancer prognosis and diagnosis. Exosomes are nanosized extracellular vesicles secreted by all types of cells and abundantly distributed in all types of body fluid, carrying diverse cargos including proteins, DNA, and RNA, which transmit regulatory signals to recipient cells. Among the cargos, exosomal proteins have always been used as immunoaffinity binding targets for exosome isolation. Increasing evidence about the function of tumor-derived exosomes and their proteins is found to be massively associated with tumor initiation, progression, and metastasis in recent years. Therefore, exosomal proteins and some nucleic acids, such as miRNA, can be used not only as targets for exosome isolation but also as potential diagnostic markers in cancer research, especially for liquid biopsy. This review will discuss the existing protein-based methods for exosome isolation and characterization that are more appropriate for clinical use based on current knowledge of the exosomal biogenesis and function. Additionally, the recent studies for the use of exosomal proteins as cancer biomarkers are also discussed and summarized, which might contribute to the development of exosomal proteins as novel diagnostic tools for liquid biopsy.

Matrix Metalloproteinases and Their Inhibitors in Pulmonary Fibrosis: EMMPRIN/CD147 Comes into Play

Pulmonary fibrosis (PF) is characterized by aberrant extracellular matrix (ECM) deposition, activation of fibroblasts to myofibroblasts and parenchymal disorganization, which have an impact on the biomechanical traits of the lung. In this context, the balance between matrix metalloproteinases (MMPs) and their tissue inhibitors of metalloproteinases (TIMPs) is lost. Interestingly, several MMPs are overexpressed during PF and exhibit a clear profibrotic role (MMP-2, -3, -8, -11, -12 and -28), but a few are antifibrotic (MMP-19), have both profibrotic and antifibrotic capacity (MMP7), or execute an unclear (MMP-1, -9, -10, -13, -14) or unknown function. TIMPs are also overexpressed in PF; hence, the modulation and function of MMPs and TIMP are more complex than expected. EMMPRIN/CD147 (also known as basigin) is a transmembrane glycoprotein from the immunoglobulin superfamily (IgSF) that was first described to induce MMP activity in fibroblasts. It also interacts with other molecules to execute non-related MMP aactions well-described in cancer progression, migration, and invasion. Emerging evidence strongly suggests that CD147 plays a key role in PF not only by MMP induction but also by stimulating fibroblast myofibroblast transition. In this review, we study the structure and function of MMPs, TIMPs and CD147 in PF and their complex crosstalk between them.

In Silico Analysis of the Multi-Targeted Mode of Action of Ivermectin and Related Compounds

Some clinical studies have indicated activity of ivermectin, a macrocyclic lactone, against COVID-19, but a biological mechanism initially proposed for this anti-viral effect is not applicable at physiological concentrations. This in silico investigation explores potential modes of action of ivermectin and 14 related compounds, by which the infectivity and morbidity of the SARS-CoV-2 virus may be limited. Binding affinity computations were performed for these agents on several docking sites each for models of (1) the spike glycoprotein of the virus, (2) the CD147 receptor, which has been identified as a secondary attachment point for the virus, and (3) the alpha-7 nicotinic acetylcholine receptor (α7nAChr), an indicated point of viral penetration of neuronal tissue as well as an activation site for the cholinergic anti-inflammatory pathway controlled by the vagus nerve. Binding affinities were calculated for these multiple docking sites and binding modes of each compound. Our results indicate the high affinity of ivermectin, and even higher affinities for some of the other compounds evaluated, for all three of these molecular targets. These results suggest biological mechanisms by which ivermectin may limit the infectivity and morbidity of the SARS-CoV-2 virus and stimulate an α7nAChr-mediated anti-inflammatory pathway that could limit cytokine production by immune cells.

CD147-spike protein interaction in COVID-19: Get the ball rolling with a novel receptor and therapeutic target

The combat against the Corona virus disease of 2019 (COVID-19), has created a chaos among the healthcare institutions and researchers, in turn accelerating the dire need to curtail the infection spread. The already established entry mechanism, via ACE2 has not yet successfully aided in the development of a suitable and reliable therapy. Taking in account the constant progression and deterioration of the cases worldwide, a different perspective and mechanistic approach is required, which has thrown light onto the cluster of differentiation 147 (CD147) transmembrane protein, as a novel route for SARS-CoV-2 entry. Despite lesser affinity towards COVID-19 virus, as compared to ACE2, this receptor provides a suitable justification behind elevated blood glucose levels in infected patients, retarded COVID-19 risk in women, enhanced susceptibility in geriatrics, greater infection susceptibility of T cells, infection prevalence in non-susceptible human cardiac pericytes and so on. The manuscript invokes the title role and distribution of CD147 in COVID-19 as an entry receptor and mediator of endocytosis-promoted entry of the virus, along with the "catch and clump" hypothesis, thereby presenting its Fundamental significance as a therapeutic target for potential candidates, such as Azithromycin, melatonin, statins, beta adrenergic blockers, ivermectin, Meplazumab etc. Thus, the authors provide a comprehensive review of a different perspective in COVID-19 infection, aiming to aid the researchers and virologists in considering all aspects of viral entry, in order to develop a sustainable and potential cure for the 2019 COVID-19 disease.

N, B. V, S. R, A. S. COVID-19: Invasion, pathogenesis and possible cure - A review

Today, Coronavirus disease (COVID-19) which is believed to be transmitted from bats to humans where the people of Wuhan city, China exposed to the wet animal market is an important international public health anxiety (Xiong et al., 2020). Although, several measures were undertaken to treat the diseases by various medical advancements and by a variety of treatment procedures, still the mortality is higher. Hence, social distancing has been implemented to control the current outburst of this pandemic which spreads through human to human transmission. As a consequence, there is a need to completely understand the route of invasions of the virus into the humans and the target receptors besides the other factors leading to the disease. Several vaccines and drugs have been developed with its own pros and cons. Many are still under the various phase of R&D and clinical trials. Here we highlight the possible entry molecules, pathogenesis, symptomatology, probable cure and the recently developed vaccines for the existing pandemic due to the COVID-19.

CD147 expression lacks prognostic relevance in esophageal cancer

Introduction

The role of CD147 as an important indicator of tumor prognosis remains controversially discussed in literature. We focused on the prognostic significance of CD147 expression in esophageal cancer patients. While some studies report that CD147 is an unfavorable prognostic factor in esophageal squamous cell carcinoma, others showed no significant correlation. However, only one study draws attention to the significance of CD147 in esophageal adenocarcinoma, which is one of the most rapidly increasing neoplasms in the western world.

Methods

To finally clarify the impact of CD147 as a prognostic factor, especially for esophageal adenocarcinomas, we analyzed CD147 expression in a tissue microarray of 359 esophageal adenocarcinomas and 254 esophageal squamous cell cancer specimens. For the immuno-histochemical analysis, we used a primary antibody specific for CD147. Staining intensity and proportion of positive tumor cells were scored (negative, weak, moderate, strong staining). These findings were compared to normal esophageal tissue and correlated to the histopathological tumor phenotype and survival data.

Results

CD147 expression was detectable in weak intensities in benign esophageal tissue (85.78%) and expressed in predominately moderate to strong intensities in esophageal cancer (88.34%). Strong CD147 immunostaining was linked to increased infiltration depth (p = 0.015) and differentiation (p = 0.016) in esophageal squamous cell cancer but revealed no significant correlation with histopathology of adenocarcinoma. Moreover, CD147 intensity was unrelated to overall survival in this collective for both subtypes of esophageal cancer.

Conclusion

Thus, our data show that CD147 has no prognostic value, neither in esophageal adenocarcinoma nor squamous cell carcinoma.

Relevance of VEGF and CD147 in different SARS-CoV-2 positive digestive tracts characterized by thrombotic damage

Several evidence suggests that, in addition to the respiratory tract, also the gastrointestinal tract is a main site of severe acute respiratory syndrome CoronaVirus 2 (SARS-CoV-2) infection, as an example of a multi-organ vascular damage, likely associated with poor prognosis. To assess mechanisms SARS-CoV-2 responsible of tissue infection and vascular injury, correlating with thrombotic damage, specimens of the digestive tract positive for SARS-CoV-2 nucleocapsid protein were analyzed deriving from three patients, negative to naso-oro-pharyngeal swab for SARS-CoV-2. These COVID-19-negative patients came to clinical observation due to urgent abdominal surgery that removed different sections of the digestive tract after thrombotic events. Immunohistochemical for the expression of SARS-CoV-2 combined with a panel of SARS-CoV-2 related proteins angiotensin-converting enzyme 2 receptor, cluster of differentiation 147 (CD147), human leukocyte antigen-G (HLA-G), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 was performed. Tissue samples were also evaluated by electron microscopy for ultrastructural virus localization and cell characterization. The damage of the tissue was assessed by ultrastructural analysis. It has been observed that CD147 expression levels correlate with SARS-CoV-2 infection extent, vascular damage and an increased expression of VEGF and thrombosis. The confirmation of CD147 co-localization with SARS-CoV-2 Spike protein binding on gastrointestinal tissues and the reduction of the infection level in intestinal epithelial cells after CD147 neutralization, suggest CD147 as a possible key factor for viral susceptibility of gastrointestinal tissue. The presence of SARS-CoV-2 infection of gastrointestinal tissue might be consequently implicated in abdominal thrombosis, where VEGF might mediate the vascular damage.

Intravenous injection of cyclophilin A realizes the transient and reversible opening of barrier of neural vasculature through basigin in endothelial cells

Neural vasculature forms the blood–brain barrier against the delivery of systemically administered therapeutic drugs into parenchyma of neural tissues. Therefore, procedures to open the blood–brain barrier with minimal damage to tissues would lead to the great progress in therapeutic strategy for intractable neural diseases. In this study, through analyses with mouse in vitro brain microvascular endothelial cells and in vivo neural vasculature, we demonstrate that the administration of cyclophilin A (CypA), a ligand of basigin which is expressed in barrier-forming endothelial cells, realizes the artificial opening of blood–brain barrier. Monolayers of endothelial cells lost their barrier properties through the disappearance of claudin-5, an integral tight junction molecule, from cell membranes in a transient and reversible manner. Furthermore, the intravenous injection of a single dose of CypA into mice resulted in the opening of blood–brain barrier for a certain period which enabled the enhanced delivery of systemically administered doxorubicin into the parenchyma of neural tissues. These findings that the pre-injection of a single dose of CypA realizes an artificial, transient as well as reversible opening of blood–brain barrier are considered to be a great step toward the establishment of therapeutic protocols to overcome the intractability of neural diseases.

The diversity of lipocalin receptors

Lipocalins are important carriers of preferentially hydrophobic molecules, but they can also bind other ligands, like highly polar siderophores or intact proteins. Consequently, they are involved in a variety of physiological processes in many species. Since lipocalins are mainly extracellular proteins, they have to interact with cell receptors to exert their biological effects. In contrast to the large number of lipocalins identified in the last years, the number of receptors known is still limited. Nevertheless, some novel findings concerning the molecules involved in cellular uptake or signaling effects of lipocalins have been made recently. This review presents a detailed overview of the receptors identified so far. The methods used for isolation or identification are described and structural as well as functional information on these proteins is presented essentially in chronological order of their initial discovery.

Cyclophilin A is an endogenous ligand for the triggering receptor expressed on myeloid cells-2 (TREM2)

Triggering receptor expressed on myeloid cells 2 (TREM2) is a cell surface receptor expressed on macrophages, microglial cells, and pre-osteoclasts, and that participates in diverse cellular function, including inflammation, bone homeostasis, neurological development, and coagulation. In spite of the indispensable role of the TREM2 protein in the maintenance of immune homeostasis and osteoclast differentiation, the exact ligand for TREM2 has not yet been identified. Here, we report a putative TREM2 ligand which is secreted from MC38 cells and identified as a cyclophilin A (CypA). A specific interaction between CypA and TREM2 was shown at both protein and cellular levels. Exogenous CypA specifically interacted and co-localized with TREM2 in RAW264.7 cells, and the physical interactions were shown to regulate TREM2 signaling transduction. The Pro¹⁴⁴ residue in the extracellular domain of TREM2 was found to be the specific binding site of CypA. When considered together, this provides evidence that CypA interacts specifically with TREM2 as a potent ligand.

Proteomics of purified lamellocytes from Drosophila melanogaster HopTum-l identifies new membrane proteins and networks involved in their functions

In healthy Drosophila melanogaster larvae, plasmatocytes and crystal cells account for 95% and 5% of the hemocytes, respectively. A third type of hemocytes, lamellocytes, are rare, but their number increases after oviposition by parasitoid wasps. The lamellocytes form successive layers around the parasitoid egg, leading to its encapsulation and melanization, and finally the death of this intruder. However, the total number of lamellocytes per larva remains quite low even after parasitoid infestation, making direct biochemical studies difficult. Here, we used the Hop^Tum-l mutant strain that constitutively produces large numbers of lamellocytes to set up a purification method and analyzed their major proteins by 2D gel electrophoresis and their plasma membrane surface proteins by 1D SDS-PAGE after affinity purification. Mass spectrometry identified 430 proteins from 2D spots and 344 affinity-purified proteins from 1D bands, for a total of 639 unique proteins. Known lamellocyte markers such as PPO3 and the myospheroid integrin were among the components identified with specific chaperone proteins. Affinity purification detected other integrins, as well as a wide range of integrin-associated proteins involved in the formation and function of cell-cell junctions. Overall, the newly identified proteins indicate that these cells are highly adapted to the encapsulation process (recognition, motility, adhesion, signaling), but may also have several other physiological functions (such as secretion and internalization of vesicles) under different signaling pathways. These results provide the basis for further in vivo and in vitro studies of lamellocytes, including the development of new markers to identify coexisting populations and their respective origins and functions in Drosophila immunity.

Role of host factors in SARS-CoV-2 entry

The zoonotic transmission of highly pathogenic coronaviruses into the human population is a pressing concern highlighted by the ongoing SARS-CoV-2 pandemic. Recent work has helped to illuminate much about the mechanisms of SARS-CoV-2 entry into the cell, which determines host- and tissue-specific tropism, pathogenicity, and zoonotic transmission. Here we discuss current findings on the factors governing SARS-CoV-2 entry. We first reviewed key features of the viral spike protein (S) mediating fusion of the viral envelope and host cell membrane through binding to the SARS-CoV-2 receptor, angiotensin-converting enzyme 2. We then examined the roles of host proteases including transmembrane protease serine 2 and cathepsins in processing S for virus entry and the impact of this processing on endosomal and plasma membrane virus entry routes. We further discussed recent work on several host cofactors that enhance SARS-CoV-2 entry including Neuropilin-1, CD147, phosphatidylserine receptors, heparan sulfate proteoglycans, sialic acids, and C-type lectins. Finally, we discussed two key host restriction factors, i.e., interferon-induced transmembrane proteins and lymphocyte antigen 6 complex locus E, which can disrupt SARS-CoV-2 entry. The features of SARS-CoV-2 are presented in the context of other human coronaviruses, highlighting unique aspects. In addition, we identify the gaps in understanding of SARS-CoV-2 entry that will need to be addressed by future studies.

SARS-CoV-2-Morphology, Transmission and Diagnosis during Pandemic, Review with Element of Meta-Analysis

The outbreak of Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2). Thus far, the virus has killed over 2,782,112 people and infected over 126,842,694 in the world (state 27 March 2021), resulting in a pandemic for humans. Based on the present data, SARS-CoV-2 transmission from animals to humans cannot be excluded. If mutations allowing breaking of the species barrier and enhancing transmissibility occurred, next changes in the SARS-CoV-2 genome, leading to easier spreading and greater pathogenicity, could happen. The environment and saliva might play an important role in virus transmission. Therefore, there is a need for strict regimes in terms of personal hygiene, including hand washing and surface disinfection. The presence of viral RNA is not an equivalent of active viral infection. The positive result of the RT-PCR method may represent either viral residues or infectious virus particles. RNA-based tests should not be used in patients after the decline of disease symptoms to confirm convalescence. It has been proposed to use the test based on viral, sub-genomic mRNA, or serological methods to find the immune response to infection. Vertical transmission of SARS-CoV-2 is still a little-known issue. In our review, we have prepared a meta-analysis of the transmission of SARS-CoV-2 from mother to child depending on the type of delivery. Our study indicated that the transmission of the virus from mother to child is rare, and the infection rate is not higher in the case of natural childbirth, breastfeeding, or contact with the mother. We hope that this review and meta-analysis will help to systemize knowledge about SARS-CoV-2 with an emphasis on diagnostic implications and transmission routes, in particular, mother-to-child transmission.

Molecular Mechanisms of Canine Osteosarcoma Metastasis

Osteosarcoma (OSA) represents the most common bone tumor in dogs. The malignancy is highly aggressive, and most of the dogs die due to metastasis, especially to the lungs. The metastatic process is complex and consists of several main steps. Assessment of the molecular mechanisms of metastasis requires in vitro and especially in vivo studies for a full evaluation of the process. The molecular and biological resemblance of canine OSA to its human counterpart enables the utilization of dogs as a spontaneous model of this disease in humans. The aim of the present review article is to summarize the knowledge of genes and proteins, including p63, signal transducer and activator of transcription 3 (STAT3), Snail2, ezrin, phosphorylated ezrin-radixin-moesin (p-ERM), hepatocyte growth factor-scatter factor (HGF-SF), epidermal growth factor receptor (EGFR), miR-9, and miR-34a, that are proven, by in vitro and/or in vivo studies, to be potentially involved in the metastatic cascade of canine OSA. The determination of molecular targets of metastatic disease may enhance the development of new therapeutic strategies.

Eyes on coronavirus

Recently, coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has spread around the world and is receiving worldwide attention. Approximately 20% of infected patients are suffering from severe disease of multiple systems and in danger of death, while the ocular complications of SARS-CoV-2-infected patients have not been reported generally. Herein, we focus on two major receptors of SARS-CoV-2, ACE2 and CD147 (BSG), in human ocular cells, and interpret the potential roles of coronaviruses in human ocular tissues and diseases.

Screening druggable targets and predicting therapeutic drugs for COVID-19 via integrated bioinformatics analysis

BACKGROUND

Since the outbreak of coronavirus disease 2019 (COVID-19) in China, numerous research institutions have invested in the development of anti-COVID-19 vaccines and screening for efficacious drugs to manage the virus.

OBJECTIVE

To explore the potential targets and therapeutic drugs for the prevention and treatment of COVID-19 through data mining and bioinformatics.

METHODS

We integrated and profoundly analyzed 10 drugs previously assessed to have promising therapeutic potential in COVID-19 management, and have been recommended for clinical trials. To explore the mechanisms by which these drugs may be involved in the treatment of COVID-19, gene-drug interactions were identified using the DGIdb database after which functional enrichment analysis, protein-protein interaction (PPI) network, and miRNA-gene network construction were performed. We adopted the DGIdb database to explore the candidate drugs for COVID-19.

RESULTS

A total of 43 genes associated with the 10 potential COVID-19 drugs were identified. Function enrichment analysis revealed that these genes were mainly enriched in response to other invasions, toll-like receptor pathways, and they play positive roles in the production of cytokines such as IL-6, IL-8, and INF-β. TNF, TLR3, TLR7, TLR9, and CXCL10 were identified as crucial genes in COVID-19. Through the DGIdb database, we predicted 87 molecules as promising druggable molecules for managing COVID-19.

CONCLUSIONS

Findings from this work may provide new insights into COVID-19 mechanisms and treatments. Further, the already identified candidate drugs may improve the efficiency of pharmaceutical treatment in this rapidly evolving global situation.

An updated review of the association of host genetic factors with susceptibility and resistance to COVID-19

The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human populations sparked a global pandemic of the coronavirus disease 2019 (COVID-19). According to preliminary data, about 14% of cases are considered severe and 5% of cases result in critical illness and, reported case fatality rates vary from 1% to more than 7%. However, the symptoms of the disease and the clinical outcome are very different in infected people. In view of these differences, it is clearly apparent that to gain insight into the biology of the SARS-CoV-2, it is important to study not just the infectious particle in itself but also to investigate the virus-host cell interactions that occur during infection. This review seeks to consider the various aspects of genetic factors in determining the susceptibility and host resistance to SARS-CoV-2 throughout the recently published literature.

Primer on the Pathogenesis of Severe COVID-19: Part One

In Part One of this exploration of the pathogenesis of coronavirus disease (COVID-19), the author will evaluate the viral and cellular immunological basis for the condition. The virus demonstrates a remarkable capability not just to evade, but to exploit host immune characteristics to perpetuate viral replication. In this regard, severe acute respiratory syndrome (SARS)/severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disables most antiviral mechanisms, including the early interferon response, and avoids detection to permit unimpeded viral multiplication. Consequently, antigen-presenting cells fail to adequately stimulate the T-cell receptor. As a consequence, T-cell p53 remains highly expressed, which in turn disables an adequate effector T-cell response. Replicating SARS-CoV-2 double-strand RNA robustly activates protein kinase R (PKR)/PKR-like endoplasmic reticulum kinase (PERK). While the virus is grossly invulnerable to its antiviral effects, PKR is crucial for effecting the cytokine milieu in COVID-19. PERK is a component of the unfolded protein response, which eventuates in autophagy. SARS virions use double-membrane vesicles and adapt PERK signalling not only to avoid autophagy, but to facilitate replication. Viral activation of PKR/PERK is mutually exclusive to NLRP3 stimulation. The NLRP3 pathway elaborates IL-1β. This is chiefly a feature of paediatric SARS/SARS-CoV-2 cases. The difficulties encountered in predicting outcome and forging effective therapeutics speaks to the breadth of complexity of the immunopathogenesis of this virus.

Increased expression of extracellular matrix metalloproteinase inducer (EMMPRIN) and MMP10, MMP23 in inflammatory bowel disease: Cross-sectional study

It has been reported that EMMPRIN is involved in the regulation of immune response and the induction of MMPs production by fibroblasts. The aim of this study was to describe the intestinal gene expression and protein production of EMMPRIN, MMP23 and MMP10 in patients with ulcerative colitis (UC) and Crohn's disease (CD) and compared them with a control group. Gene expression of EMMPRIN, MMP10 and MMP23B was measured by RT-PCR. In order to determine EMMPRIN and MMP protein expression, colonic tissues were immunostained. The results of the study showed EMMPRIN gene expression was upregulated in rectal mucosa from active (a)UC versus aCD patients (P = .045), remission (r)CD group (P = .0009) and controls (P < .0001). We detected differences between rUC and aCD (P = .004), rCD (P < .0001) or control group (P < .0001). EMMPRIN showed a higher expression in mucosa (intraepithelial lymphocytes), submucosa and adventitia (endothelial cells) from aCD patients. MMP23 levels were increased in aUC and aCD compared to rUC and rCD and the control group (P = .0001). EMMPRIN+/MMP23+─expressing cells were localized mainly in mucosa, muscular and adventitia from active UC patients. MMP10 gene expression was increased in aUC versus CD patients and the control group (P = .0001). MMP10 gene expression is associated with inflammation in UC patients (P = .0001, r²  = .585). EMMPRIN+/MMP10+─producing cells were found mainly in all intestinal layers and perivascular inflammatory infiltrates from aUC patients. In conclusion, EMMPRIN, MMP23 and MMP10 were upregulated in patients with active UC versus remission UC , CD and control groups suggesting that, they are involved in the inflammatory process.

Outbreak of COVID-19: An emerging global pandemic threat

Since the first outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Wuhan, Hubei, China in December 2019, it is now recognized as a pandemic by the World Health Organization (WHO) as more than 200 countries and territories worldwide are affected with an increasing incidence. The SARS-CoV-2 infection results in a spectrum of non-specific signs and symptoms, ranging from asymptomatic infection, to flu-like illness such as fever, cough, dry cough and fatigue, to pneumonia, acute respiratory distress syndrome, and even multi-organ failures with high morbidity and mortality. SARS-CoV-2 is mainly transmitted through respiratory droplets that infected people exhale during incubation and onset period. By 12 June 2020, over 7.5 million confirmed cases of Coronavirus disease 2019 (COVID-19) with more than 421,000 deaths in the world have been reported to the WHO. No specific medication is approved to treat COVID-19, raising the urgent need for antiviral drug development. By 12 June 2020, there are over 1000 clinical trials registered in clinicaltrials.gov for treatment of COVID-19. This review summarizes the epidemiology, virology, clinical presentation, pathophysiology, diagnosis, and particularly the antiviral drugs currently under clinical trials for treatment of SARS-CoV-2 infection, together with the challenges and perspectives of this disease are also discussed.

Downregulation of CyclophilinA/CD147 Axis Induces Cell Apoptosis and Inhibits Glioma Aggressiveness

Gliomas are the most common primary tumors in the brain with poor prognosis. Previous studies have detected high expression of Cyclophilin A (CyPA) and CD147, respectively, in glioma. However, the correlation between their expressions and glioma prognosis remains unclear. Here, we investigated the expression of CyPA and CD147 in different types of glioma and characterized their relationships with clinical features, prognosis, and cell proliferation. Results showed that CyPA and CD147 expressions were elevated in higher grade gliomas. Moreover, the knockdown of CyPA and CD147 by RNA interference significantly induced cell express apoptosis biomarkers such as Annexin V and inhibited proliferation biomarkers like EdU in glioma cells. In summary, our findings revealed that high expression of CyPA and CD147 correlated with glioma grades. Moreover, downregulation of the Cyclophilin A/CD147 axis induces cell apoptosis and inhibits glioma aggressiveness. Those indicating CyPA and CD147 could be used as both potential predictive biomarkers and a potential therapeutic target.

Ehrlichia chaffeensis Uses an Invasin To Suppress Reactive Oxygen Species Generation by Macrophages via CD147-Dependent Inhibition of Vav1 To Block Rac1 Activation

The obligatory intracellular pathogen Ehrlichia chaffeensis lacks most factors that could respond to oxidative stress (a host cell defense mechanism). We previously found that the C terminus of Ehrlichia surface invasin, entry-triggering protein of Ehrlichia (EtpE; EtpE-C) directly binds mammalian DNase X, a glycosylphosphatidylinositol-anchored cell surface receptor and that binding is required to induce bacterial entry and simultaneously to block the generation of reactive oxygen species (ROS) by host monocytes and macrophages. However, how the EtpE-C-DNase X complex mediates the ROS blockade was unknown. A mammalian transmembrane glycoprotein CD147 (basigin) binds to the EtpE-DNase X complex and is required for Ehrlichia entry and infection of host cells. Here, we found that bone marrow-derived macrophages (BMDM) from myeloid cell lineage-selective CD147-null mice had significantly reduced Ehrlichia-induced or EtpE-C-induced blockade of ROS generation in response to phorbol myristate acetate. In BMDM from CD147-null mice, nucleofection with CD147 partially restored the Ehrlichia-mediated inhibition of ROS generation. Indeed, CD147-null mice as well as their BMDM were resistant to Ehrlichia infection. Moreover, in human monocytes, anti-CD147 partially abrogated EtpE-C-induced blockade of ROS generation. Both Ehrlichia and EtpE-C could block activation of the small GTPase Rac1 (which in turn activates phagocyte NADPH oxidase) and suppress activation of Vav1, a hematopoietic-specific Rho/Rac guanine nucleotide exchange factor by phorbol myristate acetate. Vav1 suppression by Ehrlichia was CD147 dependent. E. chaffeensis is the first example of pathogens that block Rac1 activation to colonize macrophages. Furthermore, Ehrlichia uses EtpE to hijack the unique host DNase X-CD147-Vav1 signaling to block Rac1 activation.IMPORTANCEEhrlichia chaffeensis is an obligatory intracellular bacterium with the capability of causing an emerging infectious disease called human monocytic ehrlichiosis. E. chaffeensis preferentially infects monocytes and macrophages, professional phagocytes, equipped with an arsenal of antimicrobial mechanisms, including rapid reactive oxygen species (ROS) generation upon encountering bacteria. As Ehrlichia isolated from host cells are readily killed upon exposure to ROS, Ehrlichia must have evolved a unique mechanism to safely enter phagocytes. We discovered that binding of the Ehrlichia surface invasin to the host cell surface receptor not only triggers Ehrlichia entry but also blocks ROS generation by the host cells by mobilizing a novel intracellular signaling pathway. Knowledge of the mechanisms by which ROS production is inhibited may lead to the development of therapeutics for ehrlichiosis as well as other ROS-related pathologies.

Cyclosporin A suppresses Porphyromonas gingivalis lipopolysaccharide induced matrix metalloproteinases activities in the co-culture of human gingival fibroblasts and monocyte cell line THP-1

Cyclosporine-A (CsA) is a widely used immunosuppressant. In this study, we explore the pathway through which CsA suppressed the Porphyromonas gingivalis lipopolysaccharide (P.g-LPS)-induced increase in matrix metalloproteinase (MMP) activities in co-cultured human gingival fibroblasts (HGFs) and THP-1 monocytes. In the co-culture, we found that CsA inhibited the expression of cyclophilin A (CyPA), CD147 and the activities of MMPs, which were all induced by P.g-LPS. We also found that P.g-LPS and recombinant human CyPA increased activation of ERK1/2 and IκB (an NF-κB inhibitory protein), but CsA and the anti-CD147 antibody significantly inhibited these effects. Taken together, CsA in the presence of P.g-LPS might suppress MMP activities by blocking the CyPA/CD147 interaction that results in the inhibition of ERK1/2 and NF-κB signaling by interfering with the phosphorylation of ERK1/2 and IκB.

CD147 deficiency in T cells prevents thymic involution by inhibiting the EMT process in TECs in the presence of TGFβ

Thymic involution during aging is a major cause of decreased T-cell production and reduced immunity. Here, we show that the loss of CD147 on T cells prevents thymic senescence, resulting in slowed shrinkage of the thymus with age and increased production of naive T cells. This phenotype is the result of slowing of the epithelial–mesenchymal transition (EMT) process in thymic epithelial cells (TECs), which eventually leads to reduced adipocyte accumulation. In an in vitro coculture system, we found that TGFβ is an important factor in the EMT process in TECs and that it can reduce the expression of E-cadherin through p-Smad2/FoxC2 signaling. Moreover, CD147 on T cells can accelerate the decline in E-cadherin expression by interacting with Annexin A2 on TECs. In the presence of TGFβ, Annexin A2 and E-cadherin colocalize on TECs. However, CD147 on T cells competitively binds to Annexin A2 on TECs, leading to the isolation of E-cadherin. Then, the isolated E-cadherin is easily phosphorylated by phosphorylated Src kinase, the phosphorylation of which was induced by TGFβ, and finally, p-E-cadherin is degraded. Thus, in the thymus, the interaction between T cells and TECs contributes to thymic involution with age. In this study, we illuminate the mechanism underlying the triggering of the EMT process in TECs and show that inhibiting TGFβ and/or CD147 may serve as a strategy to hinder age-related thymic involution.

High expression level of peptidylprolyl isomerase A is correlated with poor prognosis of liver hepatocellular carcinoma

Peptidylprolyl isomerase A (PPIA) has been reported to be correlated with cancer. The present study investigated the prognostic values of PPIA expression levels in cancer by comparing different types of cancer using databases. High expression levels of PPIA were observed in 17 out of 17 cancer types compared with normal adjacent tissues. High expression levels of PPIA were associated with decreased overall survival in low grade glioma, acute myeloid leukemia, lung adenocarcinoma, skin cutaneous melanoma and liver hepatocellular carcinoma (LIHC). The prognostic effect of PPIA expression in LIHC was independent of tumor grade. High expression levels of PPIA were of particular prognostic value in stage 3, American Joint Committee on Cancer Tumor 3, hepatitis B virus negative and sorafenib-administered subgroups in LIHC. The expression level of PPIA was significantly associated with levels of basigin and signal transducer and activator of transcription 3, which may be major effectors of PPIA in the progression of the cancer.

CD147 mediates intrahepatic leukocyte aggregation and determines the extent of liver injury

Background

Chronic inflammation is the driver of liver injury and results in progressive fibrosis and eventual cirrhosis with consequences including both liver failure and liver cancer. We have previously described increased expression of the highly multifunctional glycoprotein CD147 in liver injury. This work describes a novel role of CD147 in liver inflammation and the importance of leukocyte aggregates in determining the extent of liver injury.

Methods

Non-diseased, progressive injury, and cirrhotic liver from humans and mice were examined using a mAb targeting CD147. Inflammatory cell subsets were assessed by multiparameter flow cytometry.

Results

In liver injury, we observe abundant, intrahepatic leukocyte clusters defined as ≥5 adjacent CD45⁺ cells which we have termed “leukocyte aggregates”. We have shown that these leukocyte aggregates have a significant effect in determining the extent of liver injury. If CD147 is blocked in vivo, these leukocyte aggregates diminish in size and number, together with a marked significant reduction in liver injury including fibrosis. This is accompanied by no change in overall intrahepatic leukocyte numbers. Further, blocking of aggregation formation occurs prior to an appreciable increase in inflammatory markers or fibrosis. Additionally, there were no observed, “off-target” or unpredicted effects in targeting CD147.

Conclusion

CD147 mediates leukocyte aggregation which is associated with the development of liver injury. This is not a secondary effect, but a cause of injury as aggregate formation proceeds other markers of injury. Leukocyte aggregation has been previously described in inflammation dating back over many decades. Here we demonstrate that leukocyte aggregates determine the extent of liver injury.

Targeting gut microbiota as a possible therapy for mastitis

Mastitis, a disease that affects both dairy herds and humans, is recognized as the most common source of losses in the dairy industry. Antibiotics have been used for years as the primary treatment for mastitis. However, abuse of antibiotics has led to the emergence of resistant strains and the presence of drug residues and has increased the difficulty of curing this disease. In addition, antibiotics kill most of the microbes that are present in the digestive tract, leading to imbalances in the gut microbiome and destruction of the ecosystem that is normally present in the gut. Gut microbiota play an important role in the host's health and could be considered the "second brain" of the body. In recent years, the gut microbiota and their metabolites, including lipopolysaccharide (LPS) and short-chain fatty acids (SCFAs), have been shown to participate in the development of mastitis. LPS is the main component of the cell walls of gram-negative bacteria. Overproduction of rumen-derived LPS injures the rumen epithelium, resulting in the entry of LPS into the blood and damaged liver function; once in the blood, it circulates into the mammary gland, increasing blood-barrier permeability and leading to mammary gland inflammation. SCFAs, which are produced by gut microbiota as fermentation products, have a protective effect on mammary gland inflammatory responses and help maintain the function of the blood-milk barrier. Recently, increasing attention has been focused on the use of probiotics as a promising alternative for the treatment of mastitis. This review summarizes the effects of the gut microbiome and its metabolites on mastitis as well as the current of probiotics in mastitis. This work may provide a valuable theoretical foundation for the development of fresh ideas for the prevention and treatment of mastitis.

CD147/Basigin Deficiency Prevents the Development of Podocyte Injury through FAK Signaling

Podocytes, which are susceptible to injury by various stimuli and stress, are critical regulators of proteinuric kidney diseases, regardless of the primary disease and pathogenesis. We further confirmed a significant correlation between urinary CD147/basigin (Bsg) levels and proteinuria in patients with focal segmental glomerulosclerosis. However, the molecular mechanism of podocyte injury involving Bsg is not fully understood. Here, the involvement of Bsg in the pathogenesis of podocyte injury was elucidated. Healthy podocytes rarely express Bsg protein. In two independent mouse models, including adriamycin-induced nephropathy and N^ω-nitro-l-arginine methyl ester (l-name)-induced endothelial dysfunction, Bsg induction in injured podocytes caused podocyte effacement, which led to development of proteinuria. Bsg silencing in cultured podocytes exposed to transforming growth factor-β suppressed focal adhesion rearrangement and cellular motility via the activation of β₁ integrin-focal adhesion kinase-matrix metallopeptidase signaling. In addition, induction of vascular endothelial growth factor and endothelin-1, which are implicated in podocyte-to-endothelial cross-communication, was lower in the supernatants of cultured Bsg-silenced podocytes stimulated with transforming growth factor-β. In this setting, Bsg may be involved in a physiological positive feedback loop that accelerates podocyte cell motility and depolarization. The current study thus suggests that Bsg silencing via suppression of β₁ integrin-focal adhesion kinase-matrix metallopeptidase signaling may be an attractive therapeutic strategy for the maintenance of podocytes in patients with proteinuric kidney diseases.

Generation and Characterization of Fibroblast-Specific Basigin Knockout Mice

Basigin is a well-known extracellular stimulator of fibroblasts and may confer resistance to apoptosis of fibroblasts in vitro under some pathological status, but its exact function in fibroblasts and the underlying mechanism remain poorly understood. The systematic Basigin gene knockout leads to the perinatal lethality of mice, which limits the delineation of its function in vivo. In this study, we generated a fibroblast-specific Basigin knock-out mouse model and demonstrated the successful deletion of Basigin in fibroblasts. The fibroblast-specific deletion of Basigin did not influence the growth, fertility and the general condition of the mice. No obvious differences were found in the size, morphology, and histological structure of the major organs, including heart, liver, spleen, lung and kidney, between the knockout mice and the control mice. The deletion of Basigin in fibroblasts did not induce apoptosis in the tissues of the major organs. These results provide the first evidence that the fibroblast-specific Basigin knock-out mice could be a useful tool for exploring the function of Basigin in fibroblasts in vivo.

Positive Correlation between Activated CypA/CD147 Signaling and MMP-9 Expression in Mice Inflammatory Periapical Lesion

Aim

Cyclophilin A (CypA)/CD147 signaling plays critical roles in the regulation of inflammation and bone metabolism. This study aimed to investigate the participation of CypA/CD147 in mice periapical lesions progression and its relationship with bone resorption.

Methodology

Periapical lesions were induced by pulp exposure in the first lower molars of 40 C57BL/6J mice. The mice were sacrificed on days 0, 7, 14, 21, 28, 35, 42, and 49. Mandibles were harvested for X-ray imaging, microcomputed tomography scanning, histologic observation, immunohistochemistry, enzyme histochemistry, and double immunofluorescence analysis. Western blot was employed to further detect the related molecular signaling pathways in LPS-stimulated RAW 264.7 cells treated with CypA inhibitor.

Results

The volume and area of the periapical lesions increased from day 0 to day 35 and remained comparably stable until day 49. Immunohistochemistry demonstrated that the CypA expression levels also increased from day 0 to day 35 and decreased until day 49, similar to CD147 expression (R² = 0.4423, P < 0.05), osteoclast number (R² = 0.5101, P < 0.01), and the expression of osteoclastogenesis-related matrix metalloproteinase 9 (MMP-9) (R² = 0.4715, P < 0.05). Serial sections further confirmed the colocalization of CypA and CD147 on osteoclasts with immunohistochemistry. And the distribution of CypA-positive or CD147-positive cells was positively correlated with the dynamics of MMP-9-positive cells by using immunofluorescence analysis. Furthermore, CD147 and MMP-9 expression in RAW 264.7 cells were both downregulated with CypA inhibitor treatment (P < 0.05).

Conclusions

The present study reveals the positive correlation of CypA/CD147 signaling and osteoclast-related MMP-9 expression in mice inflammatory periapical lesions progression. Therefore, intervention of CypA/CD147 signaling could probably provide a potential therapeutic target for attenuating inflammatory bone resorption.

Extracellular vesicles from Echinococcus granulosus larval stage: Isolation, characterization and uptake by dendritic cells

The secretion of extracellular vesicles (EVs) in helminth parasites is a constitutive mechanism that promotes survival by improving their colonization and adaptation in the host tissue. In the present study, we analyzed the production of EVs from supernatants of cultures of Echinococcus granulosus protoscoleces and metacestodes and their interaction with dendritic cells, which have the ability to efficiently uptake and process microbial antigens, activating T lymphocytes. To experimentally increase the release of EVs, we used loperamide, a calcium channel blocker that increases the cytosolic calcium level in protoscoleces and EV secretion. An exosome-like enriched EV fraction isolated from the parasite culture medium was characterized by dynamic light scattering, transmission electron microscopy, proteomic analysis and immunoblot. This allowed identifying many proteins including: small EV markers such as TSG101, SDCBP, ALIX, tetraspanins and 14-3-3 proteins; proteins involved in vesicle-related transport; orthologs of mammalian proteins involved in the immune response, such as basigin, Bp29 and maspardin; and parasite antigens such as antigen 5, P29 and endophilin-1, which are of special interest due to their role in the parasite-host relationship. Finally, studies on the EVs-host cell interaction demonstrated that E. granulosus exosome-like vesicles were internalized by murine dendritic cells, inducing their maturation with increase of CD86 and with a slight down-regulation in the expression of MHCII molecules. These data suggest that E. granulosus EVs could interfere with the antigen presentation pathway of murine dendritic cells inducing immunoregulation in the host. Further studies are needed to better understand the role of these vesicles in parasite survival and as diagnostic markers and new vaccines.

Human cystic echinococcosis, caused by chronic infection with the larval stage of Echinococcus granulosus, affects over 1 million people worldwide. This helminth parasite secretes numerous excretory/secretory products that are in contact with host tissues where it establishes hydatid cysts. In this study, we comprehensively characterized extracellular vesicles (EVs) from E. granulosus protoscoleces and metacestodes, and demonstrated for the first time that the exosome-like vesicles from helminths can interact with host dendritic cells and carry several immunoregulatory proteins. This study provides valuable data on cestode-host immune communication. Nevertheless, further research on EVs is needed to fully understand their role in the parasite-host interface and obtain new data concerning their function as therapeutic markers and diagnostic tools.

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.

The clinical relevance of plasma CD147/basigin in biopsy-proven kidney diseases

BACKGROUND

Precise understanding of kidney disease activity is needed to design therapeutic strategies. CD147/basigin is involved in the pathogenesis of acute kidney injury and renal fibrosis through inflammatory cell infiltration. The present study examined the clinical relevance of CD147 in biopsy-proven kidney diseases that lead to the progression of chronic kidney disease.

METHODS

Kidney biopsy specimens and plasma and urine samples were obtained from patients with kidney diseases, including IgA nephropathy (IgAN), Henoch-Schönlein purpura nephritis (HSPN), diabetic kidney disease (DKD), focal segmental glomerulosclerosis (FSGS), and membranous nephropathy (MN), who underwent renal biopsy between 2011 and 2014. Plasma and urinary CD147 levels were measured and evaluated for their ability to reflect histological features. Disease activity of IgAN tissues was evaluated according to the Oxford classification and the Japanese histological grading system.

RESULTS

In biopsy tissues, CD147 induction was detected in injured lesions representing renal inflammation. Plasma CD147 values correlated with eGFR in patients with inflammation-related kidney diseases such as IgAN, HSPN, and DKD. Particularly in IgAN patients, plasma CD147 levels were correlated with injured regions comprising more than 50% of glomeruli or with tubular atrophy/interstitial injury in biopsy tissues. Proteinuria showed a closer correlation with urinary values of CD147 and L-FABP. Of note, plasma and urinary CD147 levels showed a strong correlation with eGFR or proteinuria, respectively, only in DKD patients.

CONCLUSION

Evaluation of plasma and urinary CD147 levels might provide key insights for the understanding of the activity of various kidney diseases.

Human Cyclophilin B forms part of a multi-protein complex during erythrocyte invasion by Plasmodium falciparum

Invasion of human erythrocytes by Plasmodium falciparum merozoites involves multiple interactions between host receptors and their merozoite ligands. Here we report human Cyclophilin B as a receptor for PfRhopH3 during merozoite invasion. Localization and binding studies show that Cyclophilin B is present on the erythrocytes and binds strongly to merozoites. We demonstrate that PfRhopH3 binds to the RBCs and their treatment with Cyclosporin A prevents merozoite invasion. We also show a multi-protein complex involving Cyclophilin B and Basigin, as well as PfRhopH3 and PfRh5 that aids the invasion. Furthermore, we report identification of a de novo peptide CDP3 that binds Cyclophilin B and blocks invasion by up to 80%. Collectively, our data provide evidence of compounded interactions between host receptors and merozoite surface proteins and paves the way for developing peptide and small-molecules that inhibit the protein−protein interactions, individually or in toto, leading to abrogation of the invasion process.

Invasion of red blood cells by Plasmodium falciparum is a complex process and relies on several receptor-ligand interactions. Here, the authors show that human cyclophilin B binds Plasmodium surface protein PfRhopH3 and that interruption of this interaction reduces invasion by 80%.

The origin and evolution of Basigin(BSG) gene: A comparative genomic and phylogenetic analysis

Basigin (BSG), also known as extracellular matrix metalloproteinase inducer (EMMPRIN) or cluster of differentiation 147 (CD147), plays various fundamental roles in the intercellular recognition involved in immunologic phenomena, differentiation, and development. In this study, we aimed to compare the similarities and differences of BSG among organisms and explore possible evolutionary relationships based on the comparison result. We used the extensive BLAST tool to search the metazoan genomes, N-glycosylation sites, the transmembrane region and other functional sites. We then identified BSG homologs from genomic sequences and analyzed their phylogenetic relationships. We identified that BSG genes exist not only in the vertebrate metazoans but also in the invertebrate metazoans such as Amphioxus B. floridae, D. melanogaster, A. mellifera, S. japonicum, C. gigas, and T. patagoniensis. After sequence analysis, we confirmed that only vertebrate metazoans and Cephalochordate (amphioxus B. floridae) have the classic structure (a signal peptide, two Ig-like domains (IgC2 and IgI), a transmembrane region, and an intracellular domain). The invertebrate metazoans (excluding amphioxus B. floridae) lack the N-terminal signal peptides and IgC2 domain. We then generated a phylogenetic tree, genome organization comparison, and chromosomal disposition analysis based on the biological information obtained from the NCBI and Ensembl databases. Finally, we established the possible evolutionary scenario of the BSG gene, which showed the restricted exon rearrangement that has occurred during evolution, forming the present-day BSG gene.

Spongionella Secondary Metabolites, Promising Modulators of Immune Response through CD147 Receptor Modulation

The modulation of the immune system can have multiple applications such as cancer treatment, and a wide type of processes involving inflammation where the potent chemotactic agent cyclophilin A (Cyp A) is implicated. The Porifera phylum, in which Spongionella is encompassed, is the main producer of marine bioactive compounds. Four secondary metabolites obtained from Spongionella (Gracilin H, A, L, and Tetrahydroaplysulphurin-1) were described to hit Cyp A and to block the release of inflammation mediators. Based on these results, some role of Spongionella compounds on other steps of the signaling pathway mediated by this chemotactic agent can be hypothesized. In the present paper, we studied the effect of these four compounds on the surface membrane CD147 receptor expression, on the extracellular levels of Cyp A and on the ability to migrate of concanavalin (Con A)-activated T lymphocytes. Similar to a well-known immunosuppressive agent cyclosporine A (CsA), Gracilin H, A, L, and tetrahydroaplysulphurin-1 were able to reduce the CD147 membrane expression and to block the release of Cyp A to the medium. Besides, by using Cyp A as chemotactic agent, T cell migration was inhibited when cells were previously incubated with Gracilin A and Gracilin L. These positive results lead us to test the in vivo effect of Gracilin H and L in a mouse ear delayed hypersensitive reaction. Thus, both compounds efficiently reduce the ear swelling as well as the inflammatory cell infiltration. These results provide more evidences for their potential therapeutic application in immune-related diseases of Spongionella compounds.

Identification of low abundance cyclophilins in human plasma

Cylophilins (Cyps) belong to the ubiquitously distributed enzyme class of peptidyl prolyl cis/trans isomerases (EC5.2.1.8), which are foldases capable of accelerating slow steps in the refolding of denatured proteins. At least 20 different Cyp isoenzymes are broadly distributed among all organs and cellular compartments in humans. Extracellularly localized Cyps came into the scientific focus recently because of their involvement in the control of inflammatory diseases, as well as viral and bacterial infections. However, detailed insights into Cyp functions are often hampered by the lack of sensitive detection methods. We present an improved method for affinity purification and detection of Cyp in biotic samples in this manuscript. The procedure takes advantage of two novel cyclosporine A derivatives. Derivative 1 was used to capture Cyps from the sample while derivative 2 was applied for selective release from the affinity matrix. Using this approach, eight different Cyp (CypA, CypB, CypC, Cyp40 (PPID), CypE, CypD (PPIF), CypH, and CypL1) were unambiguously detected in healthy human blood plasma. Moreover, extracellular CypA was found to be partially modified by N^ε acetylation on residues Lys44, Lys133, Lys155, as well as N^α  acetylation at the N-terminal Val residue. N^α  acetylation of Ser2 residue was also found for Cyp40.