NKHs27, a sevenband grouper NK-Lysin peptide that possesses immunoregulatory and antimicrobial activity

As an effective and broad-spectrum antimicrobial peptide, NK-Lysin is attracted more and more attention at present. However, the functions and action mechanism of NK-Lysin peptides are still not comprehensive enough at present. In this study, a sevenband grouper (Hyporthodus septemfasciatus) NK-Lysin peptide, NKHs27, was identified and synthesized, and its biological functions were studied. The results indicated that NKHs27 shares 44.44%∼88.89% overall sequence identities with other teleost NK-Lysin peptides. The following antibacterial activity assay exhibited that NKHs27 was active against both Gram-negative and Gram-positive bacteria, including Staphylococcus aureus, Listonella anguillarum, Vibrio parahaemolyticus and Vibrio vulnificus. Additionally, NKHs27 showed a synergistic effect when it was combined with rifampicin or erythromycin. In the process of interaction with the L. anguillarum cells, NKHs27 changed the cell membrane permeability and retained its morphological integrity, then penetrated into the cytoplasm to act on genomic DNA or total RNA. Then, in vitro studies showed that NKHs27 could enhance the respiratory burst ability of macrophages and upregulate immune-related genes expression in it. Moreover, NKHs27 incubation improved the proliferation of peripheral blood leukocytes significantly. Finally, in vivo studies showed that administration of NKHs27 prior to bacterial infection significantly reduced pathogen dissemination and replication in tissues. In summary, these results provide new insights into the function of NK-Lysin peptides in teleost and support that NKHs27, as a novel broad-spectrum antibacterial peptide, has potential applications in aquaculture against pathogenic infections.

[Analysis of clinical features and treatment of pyoderma gangrenosum]

Objective: To explore the clinical features and treatment of pyoderma gangrenosum (PG). Methods: A retrospective observational study was conducted. From January 2012 to July 2021, 25 patients with PG who met the inclusion criteria were admitted to Beijing Fucheng Hospital, including 16 males and 9 females, with the age of onset of disease being 14 to 75 years. Among them, the classification of PG identified 17 cases of ulcerative type, 6 cases of pustular type, 1 case of proliferative type, and 1 case of bullous type. Six patients were accompanied with systemic diseases, while 19 patients were not accompanied with systemic diseases. At the same time of systemic treatment with glucocorticoids, dressing changes or surgical skin grafting was performed on the wounds. The results of laboratory and histopathological examinations, the overall curative effects and follow-up of patients, the wound healing time of patients with negative and positive microbial culture results of wound secretion specimens, and the curative effects of patients with and without systemic diseases were analyzed. Results: The results of blood routine examination of 19 patients were abnormal, and all the immunological indexes were normal in all the patients; the microbial culture results of wound secretion specimens were positive in 14 patients; and the histopathological examination results of ulcer boundary tissue in 15 patients with rapid wound progress were mainly local tissue inflammatory changes. The wounds were cured in 17 patients, mostly healed in 7 patients, and not healed in 1 patient. After one-year's follow-up, the PG in 3 patients relapsed due to self-discontinuation of medication after discharge, and the wounds were healed gradually after adjustment of medication, while the remaining patients had no relapse. The days of wound healing in 14 patients with positive microbial culture results of wound secretion specimens were 21-55 days, and the days of wound healing in 11 patients with negative microbial culture results in wound secretion specimens were 20-54 days. In the 6 patients with systemic diseases, the wounds of 3 patients were cured, and the wounds of the other 3 patients were mostly healed. In the 19 patients without systemic diseases, the wounds of 14 patients were cured, the wounds of 4 patients were mostly healed, and the wound of 1 patient was not healed. Conclusions: The laboratory examination and pathological manifestations of patients with PG lacks characteristics, and their clinical manifestations are rich and diverse, thus PG can be easily misdiagnosed. The glucocorticoids combined with immunosuppressive therapy have good effects on PG. Surgical intervention can be performed on the wounds. Specifically, excessive debridement is not recommended in the acute phase, but skin grafting can be performed in the contraction phase.

Antimicrobial and immunoregulatory activities of the derived peptide of a natural killer lysin from black rockfish (Sebastes schlegelii)

Natural killer lysin (NK-lysin) is a small molecule antimicrobial peptide secreted by natural killer cells and T lymphocytes. In this study, we characterized a cDNA sequence encoding an NK-lysin homologue (SsNKL1) from black rockfish, Sebastes schlegelii. The open reading frame (ORF) of SsNKL1 encodes a putative protein of 149 amino acids and shares 44%-87% overall sequence identities with other teleost NK-lysins. SsNKL1 possesses conserved NK-lysin family features, including a signal sequence and a surfactant-associated protein B (SapB) domain, sequence analysis revealed that SsNKL1 is most closely related to false kelpfish (Sebastiscus marmoratus) NK-lysin (with 87% sequence identity). SsNKL1 transcripts were detected in all the tested tissues, with the highest level in the kidney, followed by the spleen and gills. Upon Listonella anguillarum infection, the mRNA expression of SsNKL1 in the black rockfish was significantly up-regulated in the liver and kidney. The derived peptide SsNKLP27 from SsNKL1 was synthesized, and its biological function was studied. SsNKLP27 showed direct antibacterial activity against Gram-negative and Gram-positive bacteria, including Staphylococcus aureus, Bacillus subtilis, L. anguillarum, Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio vulnificus. SsNKLP27 treatment facilitated the bactericidal process of erythromycin by enhancing the permeability of the outer membrane. In the process of interaction with the target bacterial cells, SsNKLP27 changed the permeability and retained the morphological integrity of the cell membrane, then penetrated into the cytoplasm, and induced the degradation of genomic DNA and total RNA. In vivo studies showed that administration of SsNKLP27 before bacterial and viral infection significantly reduced the transmission and replication of pathogens in tissues. In vitro analysis showed that SsNKLP27 could enhance the respiratory burst ability and regulate the expression of some immune-related genes of macrophages. In summary, these results provided new insights into the function of NK-lysins in teleost fish and support that SsNKLP27 is a new broad-spectrum antimicrobial peptide that has a potential application prospect in aquaculture against pathogenic infection.

Evaluation of the efficacy of a novel Vibrio vulnificus vaccine based on antibacterial peptide inactivation in turbot, Scophthalmus maximus

Tongue sole tissue factor pathway inhibitor 2 (TFPI-2) C-terminus derived peptide, TC38, has previously been shown to kill Vibrio vulnificus cells without lysing the cell membrane; thus, the remaining bacterial shell has potential application as an inactivated vaccine. Therefore, this study aimed to evaluate the immune response induced by the novel V. vulnificus vaccine. The protective potential of TC38-killed V. vulnificus cells (TKC) was examined in a turbot model. Fish were intramuscularly vaccinated with TKC or FKC (formalin-killed V. vulnificus cells) and challenged with a lethal-dose of V. vulnificus. The results showed that compared with FKC, TKC was effective in protecting fish against V. vulnificus infection, with relative percent of survival (RPS) rates of 53.29% and 63.64%, respectively. The immunological analysis revealed that compared with the FKC and control groups, the TKC group exhibited: 1) significantly higher respiratory burst ability and bactericidal activity of macrophages at 7 d post-vaccination; 2) increased alkaline phosphatase, acid phosphatase, lysozyme, and total superoxide dismutase levels post-vaccination; 3) higher serum agglutinating antibody titer with corresponding higher serum bactericidal ability, and a more potent serum agglutination effect, as well as an increased IgM expression level; 4) higher expression of immune relevant genes, which were involved in both innate and adaptive immunity. Taken together, this is the first study to develop a novel V. vulnificus inactivated vaccine based on AMP inactivation, and TKC is an effective vaccine against V. vulnificus infection for aquaculture.

A teleost bactericidal permeability-increasing protein-derived peptide that possesses a broad antibacterial spectrum and inhibits bacterial infection as well as human colon cancer cells growth

The bactericidal permeability-increasing protein (BPI) is a multifunctional cationic protein produced by neutrophils with antibacterial, antitumor, and LPS-neutralizing properties. In teleost, a number of BPIs have been reported, but their functions are very limited. In this study, an N-terminal peptide, BO18 (with 18 amino acids), derived from rock bream (Oplegnathus fasciatus) BPI, was synthesized and investigated for its antibacterial spectrum, action mechanism, immunoregulatory property as well as the inhibition effects on bacterial invasion and human colon cancer cells growth. The results showed that BO18 was active against Gram-positive bacteria Bscillus subiilis, Micrococcus luteus, and Staphylococcus aureus, as well as Gram-negative bacteria Vibrio alginolyticus, Vibrio litoralis, Vibrio parahaemolyticus and Vibrio vulnificus. BO18 treatment facilitated the bactericidal process of erythromycin and rifampicin by enhancing the permeability of the outer membrane. During its interaction with V. alginolyticus, BO18 exerted its antibacterial activity by destroying cell membrane integrity, penetrating into the cytoplasm and binding to genomic DNA and total RNA. In vitro analysis indicated BO18 could enhance the respiratory burst ability and regulate the expression of immune related genes of macrophages. In vivo detection showed the administration of fish with BO18 before bacterial infection significantly reduced pathogen dissemination and replication in tissues. In addition, BO18 exerted a cytotoxic effect on the growth of human colon cancer cells HT-29. Together, these results add new insights into the function of teleost BPIs, and support that BO18 is a novel and broad-spectrum antibacterial peptide with potential to apply in fighting pathogenic infection in aquaculture.

[Clinical strategies for preservation of the exposed implant in chronic wounds and wound repair]

Objective: To explore the clinical strategies for preservation of the exposed implant in chronic wounds and wound repair. Methods: From January 2016 to January 2019, totally 8 patients (4 males and 4 females, aged 10 to 73 years) sustaining postoperative chronic wounds with exposed implants were admitted to the Fourth Medical Center of PLA General Hospital. There were 2 cases of abdominal patch exposure after abdominal trauma surgery, 2 cases of titanium plate exposure post craniocerebral surgery, 3 cases of internal fixator exposure post orthopedic surgery, and 1 case of cerebrospinal fluid drainage tube exposure after craniocerebral surgery. The wound exudate was collected for bacterial culture on admission. On the basis of glycemic control and correction of anemia and hypoproteinemia, thorough wound debridement was performed as soon as possible and the wound area after debridement ranged from 2.0 cm×0.5 cm to 6.0 cm×5.0 cm. The wounds of 4 patients were immediately closed after debridement, including 1 case by primary closure, 1 case by primary closure after local filling of platelet rich plasma gel, and 2 cases by local flap transplantation, with flap size of 10.0 cm×8.0 cm and 12.0 cm×8.0 cm, respectively. The donor sites of flaps were sutured directly and all the incisions were treated with continuous vacuum sealing drainage (VSD) after surgery. The other 4 patients were treated with continuous VSD after debridement to improve the wound bed. The wound of 1 case healed gradually, 1 case received direct wound suturing, and the wounds of 2 cases were repaired with thin split-thickness skin grafts from the thigh or the head. The results of bacterial culture of wound exudate on admission, wound healing post surgery, and follow-up were observed and recorded. Results: The bacterial culture of wound exudate on admission was positive in 6 patients, and 10 strains of bacteria were isolated with Staphylococcus epidermidis as the main pathogen. All the skin grafts or flaps of patients survived post surgery, with the incisions and wounds healed and all the implants preserved. After 1 to 3 years of follow-up, no recurrence of wound was found in any patient. Conclusions: The postoperative chronic wounds with exposed implants can be closed in primary stage by direct suturing or flap transplantation if it is clean enough on the basis of thorough debridement. The wounds with large defects or serious infection can be treated with continuous VSD firstly and then closed with direct suturing or skin grafting for delayed wound closure, thereby to reach the treatment goal of preserving the implants and repairing the wounds simultaneously.

TC26, a teleost TFPI-1 derived antibacterial peptide that induces degradation of bacterial nucleic acids and inhibits bacterial infection in vivo

At present, several reports have indicated that the C-terminal peptides of tissue factor pathway inhibitor 1 (TFPI-1) were active antibacterial peptides. However, the functions of TFPI-1 C-terminal peptides in teleost are still very limited. In this study, a C-terminal peptide, TC26 (with 26 amino acids), derived from common carp (Cyprinus carpio) TFPI-1, was synthesized and investigated for its antibacterial spectrum, action mechanism, as well as the in vivo effects on bacterial invasion. Our results showed that TC26 was active against Gram-positive bacteria Micrococcus luteus and Staphylococcus aureus, as well as Gram-negative bacterium Vibrio vulnificus. TC26 treatment facilitated the bactericidal process of erythromycin by enhancing the out-membrane permeability of V. vulnificus. During the bactericidal process, TC26 killed the target bacterial cells Vibrio vulnificus, by destroying cell membrane integrity, penetrating into the cytoplasm and inducing degradation of genomic DNA and total RNA. In vivo study showed that administration of turbot with TC26 before bacterial infection significantly reduced pathogen dissemination and replication in tissues. These results indicated that TC26 is a novel and active antibacterial peptide and may play a vital role in fighting pathogenic infection in aquaculture.

Metabolomic analysis of the toxic effect of chronic low-dose exposure to acephate on rats using ultra-performance liquid chromatography/mass spectrometry

To study the toxic effect of chronic exposure to acephate at low-dose levels, a metabolomics approach based on ultra-performance liquid chromatography/mass spectrometry (UPLC-MS) was applied. Three different doses of 0.5 mg/kg/day, 1.5 mg/kg/day, and 4.5 mg/kg/day acephate were administered to Wistar rats for 24 weeks. Endogenous metabolite profiles were obtained with UPLC-MS for all rats at six time points after treatment. Some metabolites like dimethylthiophosphate and uric acid in urine were detected at week 4. Dimethylthiophosphate, which had the most significant elevations compared with other biomarkers, was considered as an early, sensitive biomarker of exposure to acephate. Moreover, there were some endogenous metabolite changes, which demonstrated that the doses of 1.5 mg/kg/day and 4.5 mg/kg/day of acephate led to renal injury and perturbed the normal metabolic processes of rats, including glucose, nucleic acid, and protein metabolism. A connection between exposure to acephate and the metabolic disturbance has been found and interpreted. Our study indicates that the metabolomics approach based on UPLC-MS of urine provides more information on toxicity than the conventional toxicological evaluation methods in measuring changes and can be considered as a promising technique for the study of the toxic effect of acephate.