Spatiotemporal characteristics of eustachian tube development in C57BL/6 mice: Correlation between morphological and functional maturation.

BACKGROUND: The eustachian tube (ET), a critical conduit connecting the middle ear and nasopharynx, is essential for normal middle ear function. However, it remains one of the least understood anatomical structures due to its complexity and the challenges of in vitro manipulation. Historically, these challenges have hindered research into the morphology and function development of the ET. This study elucidates the spatiotemporal relationship of ET morpho-functional maturation in mice, identifying key periods and factors that lay the theoretical foundation for exploring the molecular mechanisms of ET-related diseases. RESULTS: We comprehensively characterized the ET development in C57BL/6 mice from embryonic day (E) 12.5 to postnatal day (P) 30, focusing on the development of cilia, secretory cells, surrounding glands, and macrophages. Immunostaining identified the localization and secretion patterns of the mucins Muc5b and Muc5ac within the ET. Additionally, using improved ET function assessment tools, we evaluated the developmental features of ET mucociliary clearance and ventilation functions. CONCLUSIONS: In C57BL/6 mice, E16.5 marks a critical period for middle ear cavity and ET formation. Muc5b plays a foundational role during early stages, while Muc5ac enhances function in later stages. During P7-11, despite morphological maturity, ET function remains underdeveloped but continues to improve with growth.

Caerin 1.1 and 1.9 peptides halt B16 melanoma metastatic tumours via expanding cDC1 and reprogramming tumour macrophages.

BACKGROUND: Cancer immunotherapy, particularly immune checkpoint inhibitors (ICBs) such as anti-PD-1 antibodies, has revolutionised cancer treatment, although response rates vary among patients. Previous studies have demonstrated that caerin 1.1 and 1.9, host-defence peptides from the Australian tree frog, enhance the effectiveness of anti-PD-1 and therapeutic vaccines in a murine TC-1 model by activating tumour-associated macrophages intratumorally. METHODS: We employed a murine B16 melanoma model to investigate the therapeutic potential of caerin 1.1 and 1.9 in combination with anti-CD47 and a therapeutic vaccine (triple therapy, TT). Tumour growth of caerin-injected primary tumours and distant metastatic tumours was assessed, and survival analysis conducted. Single-cell RNA sequencing (scRNAseq) of CD45+ cells isolated from distant tumours was performed to elucidate changes in the tumour microenvironment induced by TT. RESULTS: The TT treatment significantly reduced tumour volumes on the treated side compared to untreated and control groups, with notable effects observed by Day 21. Survival analysis indicated extended survival in mice receiving TT, both on the treated and distant sides. scRNAseq revealed a notable expansion of conventional type 1 dendritic cells (cDC1s) and CD4+CD8+ T cells in the TT group. Tumour-associated macrophages in the TT group shifted toward a more immune-responsive M1 phenotype, with enhanced communication observed between cDC1s and CD8+ and CD4+CD25+ T cells. Additionally, TT downregulated M2-like macrophage marker genes, particularly in MHCIIhi and tissue-resident macrophages, suppressing Cd68 and Arg1 expression across all macrophage types. Differential gene expression analysis highlighted pathway alterations, including upregulation of oxidative phosphorylation and MYC target V1 in Arg1hi macrophages, and activation of pro-inflammatory pathways in MHCIIhi and tissue-resident macrophages. CONCLUSION: Our findings suggest that caerin 1.1 and 1.9, combined with immunotherapy, effectively modulate the tumour microenvironment in primary and secondary tumours, leading to reduced tumour growth and enhanced systemic immunity. Further investigation into these mechanisms could pave the way for improved combination therapies in advanced melanoma treatment.

PEGylated IL-10: Clinical Development in Cancer Immunotherapy, Where to Go?

PURPOSEOF REVIEW: The purpose of this review is to discuss the current understanding of the pegilodecakin (PEGylated interleukin 10) and its role in the inhibition of tumour growth and metastasis. This review also focuses on clinical data published to date that have evaluated the efficacy and safety of pegilodecakin. RECENT FINDINGS: Pegilodecakin has shown significant promise in preclinical models, notable for decreased tumour burden and fewer sites of metastatic disease across various malignancies. It has been most widely assessed in a phase I/Ib clinical trial against several solid tumours, leading to the phase II and III clinical trials containing pegilodecakin and its combination with other current treatments. However, the updated data have not shown higher efficacy in renal cell carcinoma, metastatic non-small cell lung cancer or pancreatic cancer, with respect to the controls, yet the adverse events presented more mixed results. Further investigation into combination therapies including pegilodecakin is ongoing. Pegilodecakin showed promise in preclinical and phase I clinical trials on its efficacy in several solid tumours, with expected regulation of IL-10 signalling pathway observed. However, the phase II and III trials did not justify its application as potential immunotherapy in selected cancers. Further evaluation of pegilodecakin's efficacy in other cancers, either as monotherapy or in combination with the current treatments, is worth investigating clinically, which warrants to better understand its potential clinical utility.

SIRT3/GLUT4 signaling activation by metformin protect against cisplatin-induced ototoxicity in vitro.

Cisplatin is highly effective for killing tumor cells. However, as one of its side effects, ototoxicity limits the clinical application of cisplatin. The mechanisms of cisplatin-induced ototoxicity have not been fully clarified yet. SIRT3 is a deacetylated protein mainly located in mitochondria, which regulates a variety of physiological processes in cells. The role of SIRT3 in cisplatin-induced hair cell injury has not been founded. In this study, primary cultured cochlear explants exposed to 5 µM cisplatin, as well as OC-1 cells exposed to 10 µM cisplatin, were used to establish models of cisplatin-induced ototoxicity in vitro. We found that when combined with cisplatin, metformin (75 µM) significantly up-regulated the expression of SIRT3 and alleviated cisplatin-induced apoptosis of hair cells. We regulated the expression of SIRT3 to explore the role of SIRT3 in cisplatin-induced auditory hair cell injury. Overexpression of SIRT3 promoted the survival of auditory hair cells and alleviated the apoptosis of auditory hair cells. In contrast, knockdown of SIRT3 impaired the protective effect of metformin and exacerbated cisplatin injury. In addition, we found that the protective effect of SIRT3 may be achieved by regulating GLUT4 translocation and rescuing impaired glucose uptake caused by cisplatin. Our study confirmed that upregulation of SIRT3 may antagonize cisplatin-induced ototoxicity, and provided a new perspective for the study of cisplatin-induced ototoxicity.

Identification of ferroptosis genes in immune infiltration and prognosis in thyroid papillary carcinoma using network analysis.

BACKGROUND: Papillary thyroid carcinoma (PTC) is the most common thyroid cancer. While many patients survive, a portion of PTC cases display high aggressiveness and even develop into refractory differentiated thyroid carcinoma. This may be alleviated by developing a novel model to predict the risk of recurrence. Ferroptosis is an iron-dependent form of regulated cell death (RCD) driven by lethal accumulation of lipid peroxides, is regulated by a set of genes and shows a variety of metabolic changes. To elucidate whether ferroptosis occurs in PTC, we analyse the gene expression profiles of the disease and established a new model for the correlation. METHODS: The thyroid carcinoma (THCA) datasets were downloaded from The Cancer Genome Atlas (TCGA), UCSC Xena and MisgDB, and included 502 tumour samples and 56 normal samples. A total of 60 ferroptosis related genes were summarised from MisgDB database. Gene set enrichment analysis (GSEA) and Gene set variation analysis (GSVA) were used to analyse pathways potentially involving PTC subtypes. Single sample GSEA (ssGSEA) algorithm was used to analyse the proportion of 28 types of immune cells in the tumour immune infiltration microenvironment in THCA and the hclust algorithm was used to conduct immune typing according to the proportion of immune cells. Spearman correlation analysis was performed on the ferroptosis gene expression and the correlation between immune infiltrating cells proportion. We established the WGCNA to identify genes modules that are highly correlated with the microenvironment of immune invasion. DEseq2 algorithm was further used for differential analysis of sequencing data to analyse the functions and pathways potentially involving hub genes. GO and KEGG enrichment analysis was performed using Clusterprofiler to explore the clinical efficacy of hub genes. Univariate Cox analysis was performed for hub genes combined with clinical prognostic data, and the results was included for lasso regression and constructed the risk regression model. ROC curve and survival curve were used for evaluating the model. Univariate Cox analysis and multivariate Cox analysis were performed in combination with the clinical data of THCA and the risk score value, the clinical efficacy of the model was further evaluated. RESULTS: We identify two subtypes in PTC based on the expression of ferroptosis related genes, with the proportion of cluster 1 significantly higher than cluster 2 in ferroptosis signature genes that are positively associated. The mutations of Braf and Nras are detected as the major mutations of cluster 1 and 2, respectively. Subsequent analyses of TME immune cells infiltration indicated cluster 1 is remarkably richer than cluster 2. The risk score of THCA is in good performance evaluated by ROC curve and survival curve, in conjunction with univariate Cox analysis and multivariate Cox analysis results based on the clinical data shows that the risk score of the proposed model could be used as an independent prognostic indicator to predict the prognosis of patients with papillary thyroid cancer. CONCLUSIONS: Our study finds seven crucial genes, including Ac008063.2, Apoe, Bcl3, Acap3, Alox5ap, Atxn2l and B2m, and regulation of apoptosis by parathyroid hormone-related proteins significantly associated with ferroptosis and immune cells in PTC, and we construct the risk score model which can be used as an independent prognostic index to predict the prognosis of patients with PTC.

The Large Ectodomain of APP Prevents APP from being Directly Cleaved by γ-Secretase.

BACKGROUND: Alzheimer's disease (AD) is characterized by the deposition of amyloid-ß peptide (Aß) in the brain. Aß is produced by sequential ß- and γ-secretase cleavages of amyloid precursor protein (APP). Clinical trials targeting ß- and γ-secretases have all failed, partly because of the strong side effects. The aims of this work were to determine if the direct cleavage of APP by γ-secretase inhibits Aß production, and to identify γ-cleavage-inhibiting signals within APP that can be targeted to prevent Aß generation without inhibiting any enzyme. METHODS: An APP mutant mimicking secreted APPγ was overexpressed in cells to test ß-cleavage and Aß production. APP deletion and truncation mutants were overexpressed in cells to identify the γ-secretase-inhibiting domain. The intracellular transport of the mutants was examined using immunofluorescence. Co-immunoprecipitation was performed to investigate the molecular mechanisms. RESULTS: The APP N-terminal fragment mimicking the direct γ-cleavage product was not cleaved by beta-secretase 1 to produce detectable Aß. However, in cells, the C-terminal fragments of APP longer than the last 116 residues could not be cleaved by γ-secretase in cells. No deletion mutant was cleaved by γ-secretase. C99, the direct precursor of Aß, was no longer a γ-secretase substrate when green fluorescent protein was fused to its N-terminus. The large ectodomains prevented access to γ-secretase. CONCLUSIONS: Enabling the direct γ-cleavage of APP is a new and valid strategy to reduce Aß. However, APP does not inhibit γ-cleavage via a specific inhibitory sequence in the ectodomain. Other methods to fulfill the strategy may benefit AD prevention and therapy.

Caerin 1.9-Titanium Plates Aid Implant Healing and Inhibit Bacterial Growth in New Zealand Rabbit Mandibles.

OBJECTIVES: With rising rates of maxillofacial fracture, postoperative infection following rigid internal fixation is an important issue that requires immediate resolution. It is important to explore an alternative antibacterial method apart from conventional antibiotics. A controlled experiment was conducted to evaluate the effectiveness of a caerin 1.9 peptide-coated titanium plate in reducing mandibular infection in New Zealand (NZ) rabbits, aiming to minimise the risk of post-metallic implantation infection. METHODS: Twenty-two NZ rabbits were randomly divided into 3 groups. The experiment group received caerin 1.9 peptide-coated titanium plates and mixed oral bacteria exposure. The control group received normal titanium plates with mixed oral bacteria exposure. The untreated group served as a control to prove that bacteria in the mouth can cause infection. Weight, temperature, hepatic function, and C-reactive protein levels were measured. Wound and bone conditions were evaluated. Further analysis included local infection, anatomic conditions, histology, and bacterial load. RESULTS: No significant differences were found in temperature, weight, blood alanine aminotransferase, and C-reactive protein levels amongst the 3 groups. The experiment group showed the lowest amount of bacterial RNA in wounds. Additionally, the experiment group had higher peripheral lymphocyte counts compared to the control group and lower neutrophil counts on the third and seventh day postoperatively. Histologic analysis revealed lower levels of inflammatory cell infiltration, bleeding, and areas of necrosis in the experimental group compared with the controls. CONCLUSIONS: A caerin 1.9-coated titanium plate is able to inhibit bacterial growth in a NZ rabbit mandibular mixed bacteria infection model and is worth further investigation.

Improving the efficacy of cancer immunotherapy by host-defence caerin 1.1 and 1.9 peptides.

Cancer remains a major global health challenge. Immunotherapy has revolutionized the management of cancer, yet only a limited number of patients respond to such treatments. This is largely attributed to the immunosuppressive tumor microenvironment, which diminishes the effectiveness of immunotherapy. Recent studies have underscored the potential of naturally derived caerin 1 peptides, particularly caerin 1.1 and caerin 1.9, which exhibit strong antitumor effects and enhance the efficacy of immunotherapies in animal models. This review encapsulates the current research aimed at augmenting the effectiveness of immunotherapy, focusing on the role of caerin 1.1 and caerin 1.9 in boosting immunotherapeutic outcomes, elucidating possible mechanisms, and discussing their limitations and challenges.

Advances in animal models of obstructive sleep apnea.

Animal experiments play an important role in the study of the pathogenesis of human diseases and new methods of diagnosis and treatment. Due to the great differences in the anatomical structure and physiology of the upper airway between animals and humans, there is currently no animal model that can fully simulate the pathological anatomy and pathophysiological characteristics of human obstructive sleep apnea (OSA) patients. Herein, we summarizes the construction methods of several OSA animal models that have been widely used in the studies published in the last 5 years, the advantages and limitations of each model as well as related evaluation techniques are described. This information has potential to provide further guide for the development of OSA related animal experiments.

Going Beyond Host Defence Peptides: Horizons of Chemically Engineered Peptides for Multidrug-Resistant Bacteria.

Multidrug-resistant (MDR) bacteria are considered a health threat worldwide, and this problem is set to increase over the decades. The ESKAPE, a group of six pathogens including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. is the major source of concern due to their high death incidence and nosocomial acquired infection. Host defence peptides (HDPs) are a class of ribosomally synthesised peptides that have shown promising results in combating MDR, including the ESKAPE group, in- and outside bacterial biofilms. However, their poor pharmacokinetics in physiological mediums may impede HDPs from becoming viable clinical candidates. To circumvent this problem, chemical engineering of HDPs has been seen as an emergent approach to not only improve their pharmacokinetics but also their efficacy against pathogens. In this review, we explore several chemical modifications of HDPs that have shown promising results, especially against ESKAPE pathogens, and provide an overview of the current findings with respect to each modification.

Proteomic analysis of anti-MRSA activity of caerin 1.1/1.9 in a murine skin infection model and their in vitro anti-biofilm effects against Acinetobacter baumannii.

IMPORTANCE: Caerin 1.1 and caerin 1.9, natural antimicrobial peptides derived from tree frogs, have demonstrated the ability to inhibit the growth of antibiotic-resistant bacteria, comparable to certain widely used antibiotics. Additionally, these peptides exhibit the capacity to prevent or treat biofilms formed by bacteria in conjunction with bodily components. The mechanisms underlying their antibacterial effects were investigated through a mouse model of bacterial skin infection, utilizing proteomic analysis as a technological approach.

Single-nucleus RNA sequencing and deep tissue proteomics reveal distinct tumour microenvironment in stage-I and II cervical cancer.

BACKGROUND: Cervical cancer (CC) is the 3rd most common cancer in women and the 4th leading cause of deaths in gynaecological malignancies, yet the exact progression of CC is inconclusive, mainly due to the high complexity of the changing tumour microenvironment (TME) at different stages of tumorigenesis. Importantly, a detailed comparative single-nucleus transcriptomic analysis of tumour microenvironment (TME) of CC patients at different stages is lacking. METHODS: In this study, a total of 42,928 and 29,200 nuclei isolated from the tumour tissues of stage-I and II CC patients and subjected to single-nucleus RNA sequencing (snRNA-seq) analysis. The cell heterogeneity and functions were comparatively investigated using bioinformatic tools. In addition, label-free quantitative mass spectrometry based proteomic analysis was carried out. The proteome profiles of stage-I and II CC patients were compared, and an integrative analysis with the snRNA-seq was performed. RESULTS: Compared with the stage-I CC (CCI) patients, the immune response relevant signalling pathways were largely suppressed in various immune cells of the stage-II CC (CCII) patients, yet the signalling associated with cell and tissue development was enriched, as well as metabolism for energy production suggested by the upregulation of genes associated with mitochondria. This was consistent with the quantitative proteomic analysis that showed the dominance of proteins promoting cell growth and intercellular matrix development in the TME of CCII group. The interferon-α and γ responses appeared the most activated pathways in many cell populations of the CCI patients. Several collagens, such as COL12A1, COL5A1, COL4A1 and COL4A2, were found significantly upregulated in the CCII group, suggesting their roles in diagnosing CC progression. A novel transcript AC244205.1 was detected as the most upregulated gene in CCII patients, and its possible mechanistic role in CC may be investigated further. CONCLUSIONS: Our study provides important resources for decoding the progression of CC and set the foundation for developing novel approaches for diagnosing CC and tackling the immunosuppressive TME.

METTL3 Reduces Oxidative Stress-induced Apoptosis in Presbycusis by Regulating the N6-methyladenosine Level of SIRT1 mRNA.

N6-methyl adenosine (m6A) modification is known to play a crucial role in various aging-related diseases. However, its involvement in presbycusis, a type of age-related hearing loss, is not yet clear. We examined the changes in oxidative stress levels in both plasma of presbycusis patients and mice. To determine the expression of m6A and its functional enzymes, we used liquid chromatography tandem-mass spectrometry (LC-MS/MS), enzyme-linked immunosorbent assay (ELISA), and RT-PCR to analyze the total RNA of presbycusis patients blood cells (n = 8). Additionally, we detected the expression of m6A functional enzymes in the cochlea of presbycusis mice using immunohistochemistry. We assessed the effects of m6A methyltransferase METTL3 on SIRT1 protein expression, reactive oxygen species (ROS) levels, and apoptosis in an oxidative stress model of organ of Corti 1 (OC1) cells. To observe the effect on SIRT1 protein expression, we interfered with the m6A recognition protein IGF2BP3 using siRNA. In both presbycusis patients and mice, there was an increased level of oxidative stress in plasma.There was a decrease in the expression of m6A, METTL3, and IGF2BP3 in presbycusis patients blood cells. The expression of METTL3 and IGF2BP3 was also reduced in the cochlea of presbycusis mice. In OC1 cells, METTL3 positively regulated SIRT1 protein levels, while reversely regulated the level of ROS and apoptosis. IGF2BP3 was found to be involved in the regulation of SIRT1 protein expression. In addition, METTL3 may play a protective role in oxidative stress-induced injury of OC1 cells, while both METTL3 and IGF2BP3 cooperatively regulate the level of m6A and the fate of SIRT1 mRNA in OC1 cells.

Preclinical Pharmacokinetics, Biodistribution, and Acute Toxicity Evaluation of Caerin 1.9 Peptide in Sprague Dawley Rats.

Caerin 1.9 is a natural peptide derived from the skin secretions of the Australian tree frog (Litoria) with broad-spectrum antimicrobial and anticancer bioactivity. It improves the efficacy of a therapeutic vaccine and immune checkpoint inhibitor therapy when injected intratumorally and inhibits TC-1 tumor growth when applied topically through intact skin in a TC-1 murine tumor model. This paper investigated the pharmaceutical kinetic profile, the tissue distribution, and the acute safety investigation of Caerin 1.9 peptide in Sprague Dawley (SD) rats. The results showed that subcutaneous injection of Caerin 1.9 at 100 mg/kg is safe and does not cause mortality or organ malfunction in the recipient rats. For the consecutive injection of F3 at 10 mg/kg, the peak concentration (C max) of F3 displayed at 1 hr after injection in male rats was 591 ng/mL, the average drug retention time was 0.807 hr, T 1/2 was 4.58 hr, and AUC0-last was 1890 h × ng/mL. In female rats, C max was 256 ng/mL, with an average drug retention time of 2.96 hr, T 1/2 of 1.33 hr, and AUC0-last of 740 h × ng/mL. The results showed that the concentration of Caerin 1.9 in the peripheral blood peaked at 1 hour. As injected concentration increased, T 1/2 extended, and C max, AUC0-last, and volume of distribution at a steady state all increased. After 14 days of repeated subcutaneous injection at 10.0 mg/kg, no accumulation of Caerin 1.9 in plasma was observed. The results of tissue distribution showed that the Caerin 1.9 is below the LC-MS/MS detection threshold at a minimum concentration of 40 ng/g. In conclusion, Caerin 1.9 is well tolerated in rats and could be used with current immunotherapies for better management of solid tumors and genital warts.

Caerin 1.1/1.9 Enhances Antitumour Immunity by Activating the IFN-α Response Signalling Pathway of Tumour Macrophages.

Macrophages are one of the essential components of the tumour microenvironment (TME) of many cancers and show complex heterogeneity and functions. More recent research has been focusing on the characterisation of tumour-associated macrophages (TAMs). Previously, our study demonstrated that caerin 1.1/1.9 peptides significantly improve the therapeutic efficacy of combined specific immunotherapy and immune checkpoint blockade in a murine transplantable tumour model (TC-1). In this study, the mice inoculated with TC-1 tumour were immunised differently. The TAMs were isolated using flow cytometry and characterised by cytokine ELISA. The survival rates of mice with different treatments containing caerin 1.1/19 were assessed comparatively, including those with/without macrophage depletion. The single-cell RNA sequencing (scRNA-seq) data of previous studies were integrated to further reveal the functions of TAMs with the treatments containing caerin 1.1/1.9. As a comparison, the TAMs of stage I and II cervical cancer patients were analysed using scRNA-seq analysis. We demonstrate that caerin induced tumour clearance is associated with infiltration of tumours by IL-12 secreting Ly6C+F4/80+ macrophages exhibiting enhanced IFN-α response signalling, renders animals resistant to further tumour challenge, which is lost after macrophage depletion. Our results indicate that caerin 1.1/1.9 treatment has great potential in improving current immunotherapy efficacy.

Caerin 1 Peptides, the Potential Jack-of-All-Trades for the Multiple Antibiotic-Resistant Bacterial Infection Treatment and Cancer Immunotherapy.

Antibiotic resistance-related bacterial infections and cancers become huge challenges in human health in the 21st century. A number of naturally derived antimicrobial peptides possess multiple functions in host defense, including anti-infective and anticancer activities. One of which is known as the caerin 1 family peptides. The microbicidal properties of these peptides have been long discussed. The recent studies also established the usage of two members in this family, caerin 1.1 and caerin 1.9, in antimultiple antibiotic-resistant bacteria species. It is increasingly evident that caerin 1.1 and caerin 1.9 also contain additional activities in the suppression of tumor. In this review, we briefly outline the therapeutic potentials and possible mechanism of action of caerin 1.1 and 1.9 in the treatment of multiple antibiotic-resistant bacterial infection and cancer immunotherapy.

Role of the Stria Vascularis in the Pathogenesis of Sensorineural Hearing Loss: A Narrative Review.

Sensorineural hearing loss is a common sensory impairment in humans caused by abnormalities in the inner ear. The stria vascularis is regarded as a major cochlear structure that can independently degenerate and influence the degree of hearing loss. This review summarizes the current literature on the role of the stria vascularis in the pathogenesis of sensorineural hearing loss resulting from different etiologies, focusing on both molecular events and signaling pathways, and further attempts to explore the underlying mechanisms at the cellular and molecular biological levels. In addition, the deficiencies and limitations of this field are discussed. With the rapid progress in scientific technology, new opportunities are arising to fully understand the role of the stria vascularis in the pathogenesis of sensorineural hearing loss, which, in the future, will hopefully lead to the prevention, early diagnosis, and improved treatment of sensorineural hearing loss.

Caerin 1.1 and 1.9 Peptides from Australian Tree Frog Inhibit Antibiotic-Resistant Bacteria Growth in a Murine Skin Infection Model.

The host defense peptide caerin 1.9 was originally isolated from skin secretions of an Australian tree frog and inhibits the growth of a wide range of bacteria in vitro. In this study, we demonstrated that caerin 1.9 shows high bioactivity against several bacteria strains, such as Staphylococcus aureus, Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus haemolyticus in vitro. Importantly, unlike the antibiotic Tazocin, caerin 1.9 does not induce bacterial resistance after 30 rounds of in vitro culture. Moreover, caerin 1.1, another peptide of the caerin family, has an additive antibacterial effect when used together with caerin 1.9. Furthermore, caerin 1.1 and 1.9 prepared in the form of a temperature-sensitive gel inhibit MRSA growth in a skin bacterial infection model of two murine strains. These results indicate that caerin 1.1 and 1.9 peptides could be considered an alternative for conventional antibiotics. IMPORTANCE Antibiotic-resistant bacteria cause severe problems in the clinic. We show in our paper that two short peptides isolated from an Australian frog and prepared in the form of a gel are able to inhibit the growth of antibiotic-resistant bacteria in mice, and, unlike antibiotics, these peptides do not lead to the development of peptide-resistant bacteria strains.

Mg alloy surface immobilised with caerin peptides acquires enhanced antibacterial ability and putatively improved corrosion resistance.

Magnesium (Mg) has mechanical properties similar to human bones and Mg alloy is considered ideal medical implant material. However, the high velocity of degradation inside the human inner environment severely hampers the usage of Mg alloys. In this study, caerin peptide 1.9 (F3) and a modified sequence of caerin 1.1 (F1) with anti-bacterial activity, were covalently immobilised on the surface of Mg alloys by plasma chemical click reaction. The in vitro antibacterial activity and corrosion resistance of these caerin peptide-immobilised Mg alloys were investigated in Dulbecco's Modified Eagle Medium (DMEM) solution. Un-immobilised Mg alloy sample, blank drug-sensitive tablet (BASD) and a commonly used antibiotics Tazocin were used for comparison. Results showed that peptide immobilised Mg samples showed observable improved corrosion resistance and prolonged antibacterial effect compared to non-immobilised Mg alloy and free caerin peptides. These results indicate that coating Mg alloy with caerin peptides obviously increases the alloy's antibacterial ability and putatively improves the corrosion resistance in vitro. The mechanism underlying the prolonged antibacterial effect for annealed Mg alloys immobilised with the peptides (especially F3) remains unclear, which worth further experimental and theoretical investigation.

Intratumoral injection of caerin 1.1 and 1.9 peptides increases the efficacy of vaccinated TC-1 tumor-bearing mice with PD-1 blockade by modulating macrophage heterogeneity and the activation of CD8+ T cells in the tumor microenvironment.

OBJECTIVES: Developing a vaccine formula that alters the tumor-infiltrating lymphocytes to be more immune active against a tumor is key to the improvement of clinical responses to immunotherapy. Here, we demonstrate that, in conjunction with E7 antigen-specific immunotherapy, and IL-10 and PD-1 blockade, intratumoral administration of caerin 1.1/1.9 peptides improves TC-1 tumor microenvironment (TME) to be more immune active than injection of a control peptide. METHODS: We compared the survival time of vaccinated TC-1 tumor-bearing mice with PD-1 and IL-10 blockade, in combination with a further injection of caerin 1.1/1.9 or control peptides. The tumor-infiltrating haematopoietic cells were examined by flow cytometry. Single-cell transcriptomics and proteomics were used to quantify changes in cellular activity across different cell types within the TME. RESULTS: The injection of caerin 1.1/1.9 increased the efficacy of vaccinated TC-1 tumor-bearing mice with anti-PD-1 treatment and largely expanded the populations of macrophages and NK cells with higher immune activation level, while reducing immunosuppressive macrophages. More activated CD8+ T cells were induced with higher populations of memory and effector-memory CD8+ T subsets. Computational integration of the proteome with the single-cell transcriptome supported activation of Stat1-modulated apoptosis and significant reduction in immune-suppressive B-cell function following caerin 1.1 and 1.9 treatment. CONCLUSIONS: Caerin 1.1/1.9-containing treatment results in improved antitumor responses. Harnessing the novel candidate genes preferentially enriched in the immune active cell populations may allow further exploration of distinct macrophages, T cells and their functions in TC-1 tumors.