Identification of monocyte-associated pathways participated in the pathogenesis of pulmonary arterial hypertension based on omics-data.

Pulmonary arterial hypertension (PAH) is one kind of chronic and uncurable diseases that can cause heart failure. Immune microenvironment plays a significant role in PAH. The aim of this study was to assess the role of immune cell infiltration in the pathogenesis of PAH. Differentially expressed genes based on microarray data were enriched in several immune-related pathways. To evaluate the immune cell infiltration, based on the microarray data sets in the GEO database, we used both ssGSEA and the CIBERSORT algorithm. Additionally, single-cell RNA sequencing (scRNA-seq) data was used to further explicit the specific role and intercellular communications. Then receiver operating characteristic curves and least absolute shrinkage and selection operator were used to discover and test the potential diagnostic biomarkers for PAH. Both the immune cell infiltration analyses based on the microarray data sets and the cell proportion in scRNA-seq data exhibited a significant downregulation in the infiltration of monocytes in PAH. Then, the intercellular communications showed that the interaction weighs of most immune cells, including monocytes changed between the control and PAH groups, and the ITGAL-ITGB2 and ICAM signaling pathways played critical roles in this process. In addition, ITGAM and ICAM2 displayed good diagnosis values in PAH. This study implicated that the change of monocyte was one of the key immunologic features of PAH. Monocyte-associated ICAM-1 and ITGAL-ITGB2 signaling pathways might be involved in the pathogenesis of PAH.

Advances in stem cell therapy for peritoneal fibrosis: from mechanisms to therapeutics.

Peritoneal fibrosis (PF) is a pathophysiological condition caused by a variety of pathogenic factors. The most important features of PF are mesothelial-mesenchymal transition and accumulation of activated (myo-)fibroblasts, which hinder effective treatment; thus, it is critical to identify other practical approaches. Recently, stem cell (SC) therapy has been indicated to be a potential strategy for this disease. Increasing evidence suggests that many kinds of SCs alleviate PF mainly by differentiating into mesothelial cells; secreting cytokines and extracellular vesicles; or modulating immune cells, particularly macrophages. However, there are relatively few articles summarizing research in this direction. In this review, we summarize the risk factors for PF and discuss the therapeutic roles of SCs from different sources. In addition, we outline effective approaches and potential mechanisms of SC therapy for PF. We hope that our review of articles in this area will provide further inspiration for research on the use of SCs in PF treatment.

Tamoxifen exerts anti-peritoneal fibrosis effects by inhibiting H19-activated VEGFA transcription.

BACKGROUND: Peritoneal dialysis (PD) remains limited due to dialysis failure caused by peritoneal fibrosis. Tamoxifen (TAM), an inhibitor of estrogen receptor 1 (ESR1), has been reported to treat fibrosis, but the underlying mechanism remains unknown. In this study, we sought to explore whether tamoxifen played an anti-fibrotic role by affecting transcription factor ESR1. METHODS: ESR1 expression was detected in the human peritoneum. Mice were daily intraperitoneally injected with 4.25% glucose PD dialysate containing 40 mM methylglyoxal for 2 weeks to establish PD-induced peritoneal fibrosis. Tamoxifen was administrated by daily gavage, at the dose of 10 mg/kg. Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay were performed to validate ESR1 bound H19 promoter. Gain-of-function and loss-of-function experiments were performed to investigate the biological roles of H19 on the mesothelial-mesenchymal transition (MMT) of human peritoneal mesothelial cells (HPMCs). Intraperitoneal injection of nanomaterial-wrapped 2'-O-Me-modified small interfering RNA was applied to suppress H19 in the mouse peritoneum. RNA immunoprecipitation and RNA pull-down assays demonstrated binding between H19 and p300. Exfoliated peritoneal cells were obtained from peritoneal dialysis effluent to analyze the correlations between ESR1 (or H19) and peritoneal solute transfer rate (PSTR). RESULTS: ESR1 was increased significantly in the peritoneum after long-term exposure to PD dialysate. Tamoxifen treatment ameliorated high glucose-induced MMT of HPMCs, improved ultrafiltration rate, and decreased PSTR of mouse peritoneum. Tamoxifen reduced the H19 level by decreasing the ESR1 transcription of H19. Depletion of H19 reversed the pro-fibrotic effect of high glucose while ectopic expression of H19 exacerbated fibrotic pathological changes. Intraperitoneal injection of nanomaterial-wrapped 2'-O-Me-modified siRNAs targeting H19 mitigated PD-related fibrosis in mice. RNA immunoprecipitation (RIP) and RNA pull-down results delineated that H19 activated VEGFA expression by binding p300 to the VEGFA promoter and inducing histone acetylation of the VEGFA promoter. ESR1 and H19 were promising targets to predict peritoneal function. CONCLUSIONS: High glucose-induced MMT of peritoneal mesothelial cells in peritoneal dialysis via activating ESR1. In peritoneal mesothelial cells, ESR1 transcribed the H19 and H19 binds to transcription cofactor p300 to activate the VEGFA. Targeting ESR1/H19/VEGFA pathway provided new hope for patients undergoing peritoneal dialysis.

Derivation and elimination of uremic toxins from kidney-gut axis.

Uremic toxins are chemicals, organic or inorganic, that accumulate in the body fluids of individuals with acute or chronic kidney disease and impaired renal function. More than 130 uremic solutions are included in the most comprehensive reviews to date by the European Uremic Toxins Work Group, and novel investigations are ongoing to increase this number. Although approaches to remove uremic toxins have emerged, recalcitrant toxins that injure the human body remain a difficult problem. Herein, we review the derivation and elimination of uremic toxins, outline kidney-gut axis function and relative toxin removal methods, and elucidate promising approaches to effectively remove toxins.

Vibrio harveyi co-infected with Cryptocaryon irritans to orange-spotted groupers Epinephelus coioides.

The orange-spotted grouper (Epinephelus coioides) is a high economic value aquacultural fish in China, however, it often suffers from the outbreak of parasitic ciliate Cryptocaryon irritans as well as bacterium Vibrio harveyi which bring great loss in grouper farming. In the present study, we established a high dose C. irritans local-infected model which caused the mortality of groupers which showed low vitality and histopathological analysis demonstrated inflammatory response and degeneration in infected skin, gill and liver. In addition, gene expression of inflammatory cytokines was detected to assist the estimate of inflammatory response. Furthermore, we also found that the activity of Na+/K+ ATPase in gill was decreased in groupers infected C. irritans and the concentration of Na+/Cl- in blood were varied. Base on the morbidity symptom occurring in noninfected organs, we hypothesized that the result of morbidity and mortality were due to secondary bacterial infection post parasitism of C. irritans. Moreover, four strains of bacteria were isolated from the infected site skin and liver of local-infected groupers which were identified as V. harveyi in accordance of phenotypic traits, biochemical characterization and molecular analysis of 16S rDNA genes, housekeeping genes (gyrB and cpn60) and species-specific gene Vhhp2. Regression tests of injecting the isolated strain V. harveyi has showed high pathogenicity to groupers. In conclusion, these findings provide the evidence of coinfections with C. irritans and V. harveyi in orange-spotted grouper.

Risk factors of osteoporosis in elderly inpatients: A cross-sectional single-centre study.

Objective: This study aimed to identify factors significantly associated with the occurrence of osteoporosis in elderly and very elderly patients. Methods: Elderly hospitalized patients who were older than 60 years old, from the Rehabilitation Hospital from December 2019 to December 2020 were selected. Barthel index (BI), nutritional assessment, the causes of bone mineral density (BMD) reductions in elderly and elderly patients were analysed. Results: A total of 94 patients (83.56 ± 8.37 years old) were enrolled. With increasing age, the BMD of the lumbar spine, femoral neck, and femoral shaft of elderly patients significantly decreased, and the incidence of osteoporosis (OP) significantly increased. The BMD of the lumbar spine was negatively correlated with female and positively correlated with serum 25-hydroxyvitamin D levels, the difference between actual body weight and ideal body weight, and blood uric acid levels; The BMD of the femoral neck was negatively correlated with age and female, and positively correlated with height and geriatric nutrition risk index score. The BMD of the femoral shaft was negatively correlated with female and positively correlated with BI. Conclusion: With increasing age, the BMD of the lumbar spine and the femoral shaft significantly decreased, and the incidence of OP significantly increased in elderly and very elderly patients. Aric acid may protect bone health in elderly patients. Early attention to the nutritional status, exercise capacity, 25-hydroxyvitamin D level, and blood uric acid level in the elderly population can help identify high-risk elderly patients with OP.

Serum metabolic alterations in peritoneal dialysis patients with excessive daytime sleepiness.

Excessive daytime sleepiness (EDS) is associated with quality of life and all-cause mortality in the end-stage renal disease population. This study aims to identify biomarkers and reveal the underlying mechanisms of EDS in peritoneal dialysis (PD) patients. A total of 48 nondiabetic continuous ambulatory peritoneal dialysis patients were assigned to the EDS group and the non-EDS group according to the Epworth Sleepiness Scale (ESS). Ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) was used to identify the differential metabolites. Twenty-seven (male/female, 15/12; age, 60.1 ± 16.2 years) PD patients with ESS ≥ 10 were assigned to the EDS group, while twenty-one (male/female, 13/8; age, 57.9 ± 10.1 years) PD patients with ESS < 10 were defined as the non-EDS group. With UHPLC-Q-TOF/MS, 39 metabolites with significant differences between the two groups were found, 9 of which had good correlations with disease severity and were further classified into amino acid, lipid and organic acid metabolism. A total of 103 overlapping target proteins of the differential metabolites and EDS were found. Then, the EDS-metabolite-target network and the protein-protein interaction network were constructed. The metabolomics approach integrated with network pharmacology provides new insights into the early diagnosis and mechanisms of EDS in PD patients.

The Relationship Between Serum Folate Level and Residual Renal Function in CAPD Patients.

Objective: To investigate the relationship between serum folate (FA) levels and residual renal function (RRF) in continuous ambulatory peritoneal dialysis (CAPD) patients. Methods: Clinical data were collected from 180 hospitalized patients who received CAPD regularly. Patients were divided into the FA deficiency group and the FA non-deficiency group according to serum FA level. Data on age, sex, PD vintage, hemoglobin, mean corpuscular volume, serum FA, total Kt/V, residual kidney Kt/V, peritoneum Kt/V, creatinine clearance (Ccr), ultrafiltration volume, cystatin C (cytC), serum creatinine (Scr), urea nitrogen, retinol-binding protein and the primary disease were gathered from 2 groups. Statistical methods were used to analyze the relationship between serum FA level and RRF. Results: Peritoneal Kt/V, cytC, Scr were higher, and residual kidney Kt/V was lower in FA deficiency group than in non-deficiency group. Univariate correlation showed the peritoneal Kt/V, cytC, Scr negatively correlated with serum FA while residual kidney Kt/V positively correlated with serum FA, and there was a simple linear regression relationship between serum FA and residual kidney Kt/V. Differences were statistically significant (P<0.05). Conclusion: There is a relationship between serum FA and RRF in CAPD patients. Prospective studies or trials should be performed to clarify the importance of FA supplementation on RRF during peritoneal dialysis.

Mucosal immunoglobulin response in Epinephelus coioides after Cryptocaryon irritans infection.

The teleost mucosal immune system consists mainly of the skin, gills and gut, which play crucial roles in local immune responses against invading organisms. Immunoglobulins are essential molecules in adaptive immunity that perform crucial biological functions. In our study, a mucosal immunity model was constructed in Epinephelus coioides groupers after Cryptocaryon irritans infection, according to previous experience. Total IgM and IgT in the groupers increased in the serum and mucus in the immune group, whereas only pathogen-specific IgM were detected existence. More critically, pathogen-specific IgM was detected in the head kidney, gill and skin supernatants, thus suggesting that the systematic immune and mucosal immune system secreted immunoglobulins. Furthermore, an early response in the skin was observed, on the basis of the detection of pathogen-specific IgM in the skin supernatant. In conclusion, this research characterized the grouper IgM and IgT in mucosal immune responses to pathogens in the gills and skin, thus providing a theoretical basis for future studies on vaccines against C. irritans.

The Relationship Between Vitamin D and Activity of Daily Living in the Elderly.

Objective: To analyze the association between vitamin D and the performance of activity of daily living in the elderly. Methods: A total of 94 patients over the age of 65 were eligible to participate if they had undergone a bone mineral density test and if they were in a stable health condition. Subjects were further divided into two groups according to activity of daily living (ADL): the score over 40 of the patients as the high ADL group and the below as the low ADL group. Results: According to univariate analysis, the mean of total hip T score, serum creatinine/cystatin C ratio (CCR), and vitamin D were significantly different between the two groups (P=0.024, 0.008, 0.010). Multivariate ORs showed that the CCR (OR: 0.948; 95%CI: 0.910-0.989; P=0.013) and vitamin D (OR: 865; 95%CI: 0.752-0.994; P=0.047) were inversely associated with having low ADL. Furthermore, on multiple linear regression analysis, the Barthel ADL index was related to geriatric nutritional risk index (GNRI), CCR and vitamin D but independent of patients' age with the slope of 0.732, 0.539, and 0.689 separately, reflected the stronger relative within the variables. Conclusion: We demonstrated that there is a negative correlation of CCR and vitamin D with having low ADL in elderly population. Monitoring the trend of serum vitamin D and CCR, may have a role in the early detection of low ADL with loss of muscle mass and strength in the population of the elderly.

The Spatial Distribution of Renal Fibrosis Investigated by Micro-probe Terahertz Spectroscopy System.

Renal fibrosis, which is characterized as progressive extracellular matrix accumulation, is a common feature of different stages of chronic kidney disease, and the degree of fibrosis is strongly associated with renal function. In clinical practice, precise understanding of the space distribution of fibrosis is extremely important for the diagnosis and prognosis of renal disease. Rapid advances in terahertz (THz) technology have been made, and this technology has a broad application in bio-detection, as it can interact and measure the collective vibrations and rotations of molecular groups. It is well known that hydroxyproline (HYP) is the key component of collagen, which is synthesized by fibroblasts to maintain the extracellular matrix, and HYP content detection in tissue homogenate can be achieved by classical biochemistry method. In this study, a THz microprobe system was employed to conduct THz microspatial scanning with a resolution of 20 µm. Both the content and distribution of HYP were directly characterized by the THz absorption spectrum. The absorption intensity in the THz spectrum was used to determine HYP density in renal tissues; therefore, the fibrosis change in the kidneys can be determined using THz scanning at micrometer resolution, which provides more possibilities for precise diagnosis of renal fibrosis.

Protection of Grouper Against Cryptocaryon irritans by Immunization With Tetrahymena thermophila and Protective Cross-Reactive Antigen Identification.

Vaccination is an effective method to prevent Cryptocaryon irritans infection. Although some vaccines have been developed, large-scale production of these vaccines is costly. Development of a heterogenous vaccine generated by low-cost antigens is an alternative method. In the present study, grouper immunized with Tetrahymena thermophila, a free-living ciliate that easily grows in inexpensive culture media at high density, showed protective immunity against C. irritans infection. Higher immobilization against C. irritans theronts was detected in T. thermophila-immunized grouper serum, which suggested the existence of a cross-reactive antibody in the serum. By immunoprecipitation and mass spectrometry analyses, tubulin was identified as a potential cross-reactive antigen between C. irritans and T. thermophila. Recombinant T. thermophila tubulin protein (rTt-tubulin) and its antibody were prepared, and immunofluorescence showed that both C. irritans and T. thermophila cilia were stained by the anti-rTt-tubulin antibody. Grouper immunized with rTt-tubulin showed a reduced infective rate after the C. irritans challenge. An enhanced level of C. irritans-binding immunoglobulin M (IgM) antibody was detected in serum from rTt-tubulin-immunized grouper. Moreover, specific antibodies were also found in the mucus and tissue culture medium from rTt-tubulin-immunized grouper. Overall, these findings suggested that vaccination with T. thermophila elicits cross-reactive protective immunity in grouper against C. irritans, and T. thermophila may be a potential heterologous antigen for vaccine development.

Production of monoclonal antibody against grouper (Epinephelus coioides) CD4-1 and the distribution of CD4-1+ cells.

CD4-a transmembrane glycoprotein molecule expressed on the surface of helper T (Th) cells-plays a central role in adaptive immune protection. In the current study, we developed a monoclonal antibody (mAb) against the grouper CD4-1. Western blotting and immunohistochemistry results revealed that the CD4-1 mAb could recognize the recombinant and natural protein of grouper CD4-1 as well as the CD4-1+ cells in the various tissues from grouper. Tissue distribution analyses revealed that the grouper CD4-1+ cells were expressed in all tissues tested in the healthy grouper, with greater localization in the thymus, head kidney, and spleen tissues. In addition, we tested the changes in the proportion of CD4-1+ cells in the thymus, head kidney, and the gills of grouper post the infection by C. irritans. Our data suggest that the CD4-1 mAb produced against grouper in the current study can be used as a tool to characterize CD4-1+ cells and to investigate the functions of the grouper CD4-1+ cells in the host response against pathogens infection.

Transcriptomic analysis reveals innate immune mechanisms of an underlying parasite-resistant grouper hybrid (Epinephelus fuscogutatus × Epinephelus lanceolatus).

Hybridization is an artificial breeding strategy for generating potentially desirable offspring. Recently, a novel Hulong grouper hybrid (Epinephelus fuscogutatus × Epinephelus lanceolatus) yielded significant growth superiority over its parent. Improved innate immunity is considered as another desirable feature during hybridization. However, whether this Hulong grouper achieved disease resistance has not yet been revealed. In this study, we first examine the infection intensity of C. irritans in the Hulong grouper, and found that the Hulong grouper is less susceptible to C. irritans primary infection. A higher immobilization titer was found in the infected Hulong grouper at Day 2 when compared with the control grouper. Furthermore, severe hyperplasia was observed in the orange-spotted grouper, but not in the Hulong grouper's skin epidermis. To further understand the innate immune mechanism against C. irritans, we conducted a comparative transcriptome analysis of the Hulong grouper during the infection. There are 6464 differentially expressed genes (DEGs) identified in the skin between the control and infected Hulong grouper. This indicates that the innate immune components, such as the complement system, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, Interleukin 17 (IL-17) signaling pathway, and Toll-like receptor (TLR) signaling pathway were up-regulated during the infection. These results show that the C. irritans infection can induce a remarkable inflammatory response in the Hulong grouper. Moreover, a total of 75 pairs of orthologs with the ratio of nonsynonymous (Ka) to synonymous (Ks) substitutions ＞1, considered rapidly evolving genes (REGs), was identified between the Hulong and orange-spotted grouper. More critically, most REGs were enriched in the immune system, suggesting that rapid evolution of the immune system might occur in the Hulong grouper. These results provide a more comprehensive understanding of the innate immunity mechanism of the hybrid Hulong grouper.

Delayed bowel perforation after instilling over warmed peritoneal dialysate.

BACKGROUND: Peritoneal dialysis (PD) is a safe and home-based treatment for end-stage renal disease (ESRD) patients. The direct thermal damage of abdominal organs is very rare. CASE PRESENTATION: We report a peritoneal dialysis patient presented abdominal pain and feculent effluent 3 weeks after he instilled hot dialysis solution. In spite of emergency exploratory laparotomy and active treatment, the patient died of septic shock. Biopsy revealed necrosis and perforation of the intestines. CONCLUSIONS: Delayed bowel perforation by hot fluid is very rare. Standardized performance is of the first importance for peritoneal dialysis patients.

Characterization and functional analysis of hybrid pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀) complement C3 against Cryptocaryon irritans infection.

Pearl gentian grouper is a new aquacultural hybrid resulted from breeding of female tiger grouper (Epinephelus fuscogutattus) and male giant grouper (E. lanceolatus). Our preliminary study found that pearl gentian grouper exhibits less susceptible to the primary infection of Cryptocaryon irritans, which is an important parasitic ciliate in marine aquaculture, indicated that pearl gentian grouper might own a strong innate immune system. Complement system play key roles in innate immunity, whether pearl gentian grouper's complement component contribute for the defensing against the C. irritans infection remain unclear. In the present study, we found that C. irritans can be immobilized by untreated serum but not heat-treated serum from pearl gentian grouper, suggested that the heat-labile components in serum are responsible for the immobilization of C. irritans. Moreover, we cloned and characterized the encoding sequence of pearl gentian grouper complement C3 (PGC3), a key component in complement system. We also found that the expression level of PGC3 was increased in infected grouper serum when compared with that of control grouper. Furthermore, the binding of PGC3 on the surface of C. irritans trophonts located on the grouper skin was detected. These data suggested that pearl gentian grouper's complement system indeed play roles in the immune response against the C. irritans infection.

Recommendations for prevention and management of COVID-19 in peritoneal dialysis patients.

The World Health Organization characterized coronavirus disease (COVID-19) as a pandemic on March 11, 2020. Peritoneal dialysis patients have a weakened immune system that is associated with a high morbidity of infection. Thus, COVID-19 prevention measures and management for patients on peritoneal dialysis are urgent and critical. Based on published research on COVID-19 and previous clinical practices for similar coronavirus outbreaks, we aimed to make recommendations to manage patients undergoing peritoneal dialysis.

Molecular hydrogen regulates PTEN-AKT-mTOR signaling via ROS to alleviate peritoneal dialysis-related peritoneal fibrosis.

As a convenient, effective and economical kidney replacement therapy for end-stage renal disease (ESRD), peritoneal dialysis is available in approximately 11% of ESRD patients worldwide. However, long-term peritoneal dialysis treatment causes peritoneal fibrosis. In recent years, the application potential of molecular hydrogen in the biomedicine has been well recognized. Molecular hydrogen selectively scavenges cytotoxic reactive oxygen species (ROS) and acts as an antioxidant. In this experiment, a high glucose-induced peritoneal fibrosis mouse model was successfully established by intraperitoneal injection of high glucose peritoneal dialysate, and peritoneal fibrosis mice were treated with hydrogen-rich peritoneal dialysate. In addition, in vitro studies of high glucose-induced peritoneal fibrosis were performed using MeT-5A cells. In vitro and in vivo experiments show that molecular hydrogen could inhibit peritoneal fibrosis progress induced by high glucose effectively. Furthermore, it has been found that molecular hydrogen alleviate fibrosis by eliminating intracellular ROS and inhibiting the activation of the PTEN/AKT/mTOR pathway. The present data proposes that molecular hydrogen exerts the capacity of anti-peritoneal fibrosis through the ROS/PTEN/AKT/mTOR pathway. Therefore, molecule hydrogen is a potential, safe, and effective treatment agent, with peritoneal protective property and great clinical significance.

Hypoxia induces tumor cell growth and angiogenesis in non-small cell lung carcinoma via the Akt-PDK1-HIF1α-YKL-40 pathway.

BACKGROUND: As one of the most common forms of cancer, non-small cell lung carcinoma (NSCLC), is characterized by oxygen deprivation (hypoxia). The transcription factor hypoxia-inducible factor (HIF)-1α is a major mediator which responds hypoxia and regulates many contributing factors. The various modes of hypoxia regulation are frequently the focus of research studies. With reference to previous published research, we hypothesized that hypoxia promotes the growth and angiogenesis of NSCLC via the Akt-PDK1-HIF1α-YKL-40 pathway, and verified it. METHODS: We mainly investigated changes in related factor expression between differently treated CL1-5 cells. We carried out overexpression and underexpression transfection, Western blot, rt-PCR and ELISA, and observed cellular biological behaviors by CCK-8 migration and invasion assay, and tube formation assay. RESULTS: A hypoxic environment significantly increased the phosphorylation of Akt and PDK1 in mitochondria. The hypoxia-induced accumulation of p-Akt in mitochondria activated PDK1 phosphorylation, promoted the expression of HIF1α, and the expression of YKL-40. The overexpression of YKL-40 promoted the proliferation, migration, invasion and tubule formation of CL1-5 cells. CONCLUSIONS: A hypoxic tumor microenvironment can promote the expansion and angiogenesis of NSCLC cells through the Akt-PDK1-HIF1α-YKL-40 pathway. This may provide a new mechanism and potential interventional target for anti-vascular lung cancer therapy.

Identification and characterization of c-raf from orange-spotted grouper (Epinephelus coioides).

C-Raf proto-oncogene serine/threonine kinase is a mitogen-activated protein kinase (MAP) kinase kinase, which can initiate a mitogen-activated protein kinase (MAPK) cascade by phosphorylating the dual-specific MAP kinase kinases (MEK1/2), and in turn activate the extracellular signal-regulated kinases (ERK1/2). To study the function of c-Raf in teleost fish, a c-Raf cDNA sequence from orange-spotted grouper (Epinephelus coioides) was cloned. Ecc-Raf shared 81%-99% amino acid identity with other vertebrate c-Raf molecules, and shared the highest amino acid identity (99%) with Lates calcarifer c-Raf. Genomic structure analysis revealed that grouper c-Raf shared a conserved exon structure with other vertebrates. Tissue distribution showed that Ecc-Raf was mainly transcribed in systemic immune organs. Ecc-Raf was distributed throughout the cytoplasm of transfected GS cells and the overexpression of Ecc-Raf only slightly enhanced the activation of Activator protein 1. The phosphorylation levels of Ecc-Raf can be induced by PMA and H2O2 treatment, in contrast to DMSO or untreated HKLs. Moreover, the phosphorylation level of the Raf-MEK-ERK axis was downregulated after 24 h of SGIV infection. On the other hand, the total level and phosphorylation level of c-Raf significantly increased post C. irritans infection and showed an enhanced level post immunization. The results of this study suggested that the Raf-MEK-ERK cascade was involved in the response to viral or parasitic infections.