Amino Acid Peptide Research Articles

Intestinal Amino Acid Transport and Metabolic Health.

Amino acids derived from protein digestion are important nutrients for the growth and maintenance of organisms. Approximately half of the 20 proteinogenic amino acids can be synthesized by mammalian organisms, while the other half are essential and must be acquired from the nutrition. Absorption of amino acids is mediated by a set of amino acid transporters together with transport of di- and tripeptides. They provide amino acids for systemic needs and for enterocyte metabolism. Absorption is largely complete at the end of the small intestine. The large intestine mediates the uptake of amino acids derived from bacterial metabolism and endogenous sources. Lack of amino acid transporters and peptide transporter delays the absorption of amino acids and changes sensing and usage of amino acids by the intestine. This can affect metabolic health through amino acid restriction, sensing of amino acids, and production of antimicrobial peptides.

Precision engineered peptide targeting leukocyte extracellular traps mitigate acute kidney injury in Crush syndrome

Crush syndrome induced by skeletal muscle compression causes fatal rhabdomyolysis-induced acute kidney injury (RIAKI) that requires intensive care, including hemodialysis. However, access to crucial medical supplies is highly limited while treating earthquake victims trapped under fallen buildings, lowering their chances of survival. Developing a compact, portable, and simple treatment method for RIAKI remains an important challenge. Based on our previous finding that RIAKI depends on leukocyte extracellular traps (ETs), we aimed to develop a novel medium-molecular-weight peptide to provide clinical treatment of Crush syndrome.We conducted a structure-activity relationship study to develop a new therapeutic peptide. Using human peripheral polymorphonuclear neutrophils, we identified a 12-amino acid peptide sequence (FK-12) that strongly inhibited neutrophil extracellular trap (NET) release in vitro and further modified it by alanine scanning to construct multiple peptide analogs that were screened for their NET inhibition ability. The clinical applicability and renal-protective effects of these analogs were evaluated in vivo using the rhabdomyolysis-induced AKI mouse model.One candidate drug [M10Hse(Me)], wherein the sulfur of Met10 is substituted by oxygen, exhibited excellent renal-protective effects and completely inhibited fatality in the RIAKI mouse model. Furthermore, we observed that both therapeutic and prophylactic administration of M10Hse(Me) markedly protected the renal function during the acute and chronic phases of RIAKI.In conclusion, we developed a novel medium-molecular-weight peptide that could potentially treat patients with rhabdomyolysis and protect their renal function, thereby increasing the survival rate of victims affected by Crush syndrome.

Application of electronic tongue in umami detection and soy sauce refining process.

The article systematically investigated the response behaviors of lipid-film equipped umami taste sensor to various umami compounds, including typical umami substances (umami amino acids, GMP, IMP, disodium succinate) and novel umami chemicals (umami peptide and Amadori rearrangement product of umami amino acid). The umami taste sensor has great specificity to all umami substances. Relationships between output values and concentrations of umami substances in certain ranges were consistent with Weber-Fechner law. The umami synergistic effect detected by the sensor was in great agreement with human sensory results as well, fitting logarithm model. Moreover, the taste profile mixing model of raw soy sauce was established using five different taste sensors and principal component analysis, realizing the simplification of soy sauce blending and acceleration of the soy sauce refining process. Thus, flexible design of the experimental procedure and multi-analysis of the sensor data is essential.

Phase I study of NEROFE and doxorubicin in KRAS-mutated ST2-positive solid tumors.

TPS2667 Background: KRAS-mutated tumors are notoriously difficult to treat clinically with targeted therapies. Recent advances targeting KRAS G12C with sotorasib and adagrasib are encouraging but limited to a small subset of patients. NEROFE is a 14 amino acid peptide which inhibits suppression of tumorigenicity 2 (ST2; member of the interleukin 1 [IL-1] receptor family and IL-33 receptor), a novel immune checkpoint present on tumor cells and tumor-associated macrophages. ST2 blockade with NEROFE has been shown to transform an immunosuppressive tumor microenvironment into an immune-stimulatory microenvironment. NEROFE also has been shown to induce microRNA miR-217 which downregulates KRAS and MAPK1/2 gene expression in preclinical models. When combined with low-dose doxorubicin, NEROFE has a synergistic effect on inducing apoptosis in KRAS-mutated, ST2-positive cell lines and xenograft models. Methods: This is a phase I trial of NEROFE given at 48 mg/m2 (dose level [DL] -1), 96 mg/m2 (DL1), 192 mg/m2 (DL2), or 288 mg/m2 (DL3) IV weekly with doxorubicin 8 mg/m2 IV weekly. A standard 3+3 dose escalation/de-escalation is used. The primary objective is to determine the recommended phase II dose. Patients are eligible if they have an advanced solid tumor with a KRAS mutation and ST2-positivity (via immunohistochemistry [IHC], centrally confirmed with pre-screening allowed). Patients must have measurable disease amenable to serial biopsy. Patients must have had progression or intolerance to all standard therapies or must decline available standard therapy. Pharmacokinetic profiles will be analyzed from serial blood draws pre- and 1, 2, 4, 6, and 24 hours post-infusion on cycle 1 day and cycle 2 day 1. Pre- and on-treatment tumor biopsies are mandatory. Correlative studies include IHC for ST2 expression, immune cell infiltration and blood-based analyses of KRAS mRNA, miR-217, and cytokines. Enrollment to DL1 began in Q1 2023 (NCT05661201). Clinical trial information: NCT05661201 .

Phase 1b multicenter study to evaluate CHM 1101 in patients with recurrent or progressive glioblastoma.

TPS2086 Background: Glioblastoma multiforme (GBM) is the most common and most aggressive primary brain tumor. More than 300,000 new cases are diagnosed globally with over 250,000 deaths each year (Sung H, et al. CA Cancer J Clin. 2021). Patients with recurrent GBM have a poor prognosis, with limited treatment options and a median survival of less than 1 year (Gallego. Curr Oncol, 2015). While prior attempts to treat GBM with chimeric antigen receptor (CAR) T-cells have been limited by tumor heterogeneity, chlorotoxin (CLTX)-directed CAR T-cells in mice demonstrated broad anti-tumor activity and prolonged survival with no off-tumor toxicity or antigen escape (Wang, et al. Sci Transl Med, 2020). CLTX, a 36–amino acid peptide identified in scorpion venom, selectively binds to malignant glioma cells through matrix metalloproteinase-2 (MMP2) and clinical administration of CLTX-based biologics has been well tolerated in patients (Mamelak, et al. J Clin Oncol, 2005, Patil, et al. Neurosurgery, 2019). CHM 1101 is the first CAR T to utilize CLTX as its tumor targeting domain for autologous CAR T-cell therapy. A single-center first-in-human phase 1 study of CHM 1101 in patients with recurrent GBM is ongoing. Methods: Clinical Trial NCT05627323 is a phase 1b, multi-center study of CHM 1101 in adult subjects with MMP2+ recurrent or progressive GBM after standard therapy. After leukapheresis and tumor resection, pts will receive CHM 1101 at Dose Level 1 (240 × 106 CAR T cells) or Dose Level 2 (440 x 106d CAR T-cells), divided across 3 once-weekly intracranial (intracavitary and intraventricular) administrations; after disease assessment at 28 days, additional doses of CHM 1101 can be administered on a weekly schedule. Eligible subjects have a prior histologically confirmed diagnosis of a grade 4 GBM, a grade 2 or 3 malignant glioma with radiographic progression consistent with a grade 4 GBM (IDH wild type), grade 4 diffuse astrocytoma (IDH mutant), or a unifocal relapse of GBM. MMP2+ tumor expression is confirmed by IHC (≥20% moderate/high MMP2 score [2+ or 3+]). The primary endpoint is safety; key secondary endpoints include feasibility, progression-free survival, overall survival, response rate (RANO criteria), and cellular kinetics. Recruitment is ongoing. Clinical trial information: NCT05627323 .

Phase III study to evaluate the efficacy and safety of GLSI-100 (GP2 + GM-CSF) in breast cancer patients with residual disease or high-risk PCR after both neoadjuvant and postoperative adjuvant anti-HER2 therapy: Flamingo-01.

TPS617 Background: GP2 is a biologic nine amino acid peptide of the HER2/ neu protein delivered in combination with Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) that stimulates an immune response targeting HER2/neu expressing cancers, the combination known as GLSI-100. In a prospective, randomized, single-blinded, placebo-controlled, multicenter Phase IIb study, no recurrences were observed in the HER2+ population after 5 years of follow-up, if the patient was treated with GLSI-100, survived, and was followed for more than 6 months ( p = 0.0338). Immunotherapy elicited a potent response measured by skin tests and immunological assays. Of the 146 patients that have been treated with GLSI-100 over 4 clinical trials, GLSI-100 was well-tolerated and no serious adverse events observed were considered related to the immunotherapy. Methods: This Phase III trial is a prospective, randomized, double-blinded, multi-center study. After 1 year of trastuzumab-based therapy, 6 intradermal injections of GLSI-100 or placebo will be administered over the first 6 months and 5 subsequent boosters will be administered over the next 2.5 years for a total of 11 injections over 3 years. The participant duration of the trial will be 3 years treatment plus 1 additional year follow-up for a total of 4 years following the first year of treatment with trastuzumab-based therapy. Patients will be stratified based on residual disease status at surgery, hormone receptor status and region. Approximately 498 patients will be enrolled. To detect a hazard ratio of 0.3 in invasive breast cancer free survival (IBCFS), 28 events will be required. An interim analysis for superiority and futility will be conducted when at least 14 events have occurred. This sample size provides 80% power if the annual rate of events in placebo patients is 2.4% or greater. Up to 100 non-HLA-A*02 subjects will be enrolled in an open-label arm. The patient population is defined by these key eligibility criteria: HER2/neu positive and HLA-A*02; residual disease or High risk pCR (Stage III at presentation) post neo-adjuvant therapy; exclude stage IV; completed at least 90% of planned trastuzumab-based therapy. Trial objectives were to determine if GP2 therapy increases IBCFS, to assess the safety profile of GP2 and to monitor immunologic responses to treatment and assess relationship to efficacy and safety. The study has been initiated at a number of sites in the US. The study is also expected to be opened in Spain, Germany, and France. Clinical trial information: NCT05232916 .

On the interactions of peptides with gold nanoparticles: effects of sequence and size

Peptide-based self-assembly and synthesis techniques have emerged as a viable approach to designing active and stable inorganic nanostructures in aqueous media. In the present study, we use all-atom molecular dynamic (MD) simulations to study the interactions of ten short peptides (namely A3, AgBP1, AgBP2, AuBP1, AuBP2, GBP1, Midas2, Pd4, Z1, and Z2) with different gold nanoparticles (of different diameters ranging from 2 to 8 nm). Our MD simulation results imply that the gold nanoparticles have a remarkable effect on the stability and conformational properties of peptides. Moreover, the size of the gold nanoparticles and the type of peptide amino acid sequences play important roles in the stability of the peptide-AuNP complexes. Our results reveal that some amino acids such as Tyr, Phe, Met, Lys, Arg, and Gln have direct contact with the metal surface in comparison with Gly, Ala, Pro, Thr, and Val residues. The peptide adsorption on the surface of the gold nanoparticles is favorable from the energetic viewpoint, in which the van der Waals (vdW) interactions between the peptides and metal surface can be considered as one of the driving forces for the complexation process. The calculated Gibbs binding energies indicate that AuNPs have more sensitivity against the GBP1 peptide in the presence of different peptides. Overall, the results of this study can provide new insight into the peptide interaction with the gold nanoparticles from the molecular viewpoint, which can be important for designing new biomaterials based on the peptides and gold nanoparticles. Communicated by Ramaswamy H. Sarma

Effects of the interaction between Aeromonas sobria and Macrococcus caseolyticus on protein degradation of refrigerated sturgeon fillets: Novel perspective on fish spoilage

This study aims to investigate the impact of nonspecific spoilage dominant bacteria on fish protein degradation and elucidate the effect of dominant bacteria interactions on the spoilage of sturgeon fillets during refrigeration. Macrococcus caseolyticus and Aeromonas sobria were individually inoculated and co-inoculated into sturgeon fillets, and their influence on protein degradation, oxidation, muscle structure changes, and spoilage indicators were examined using a sterilized fish fillet model. The results revealed that the nonspecific spoilage dominant bacteria M. caseolyticus disrupted the protein structure by secreting proteases and aminopeptidases (159.7 and 112.6 U/g respectively, at the end of storage), leading to the hydrolysis of protein into small peptide molecules and amino acids. Although M. caseolyticus exhibited a weak ability to produce spoilage metabolites, its presence in the co-culture group provided nutrients for the growth and metabolism of A. sobria. This synergistic interaction promoted muscle structure breakdown and protein degradation in sturgeon fillets during the late storage period, resulting in increased spoilage metabolites and accelerated oxidation. Peptidomics analysis revealed that A. sobria and M. caseolyticus influenced protein degradation by affecting molecular functions and altering biological processes, including interspecies interaction, molecular transduction activity, and regulation of molecular functions. This work unveils the mechanism of protein degradation in sturgeon fillets induced by spoilage bacteria during refrigerated storage, providing a foundation for quality control of aquatic products.

Extent of N-Terminus Folding of Semenogelin 1 Cleavage Product Determines Tendency to Amyloid Formation.

It is known that four peptide fragments of predominant protein in human semen Semenogelin 1 (SEM1) (SEM1(86-107), SEM1(68-107), SEM1(49-107) and SEM1(45-107)) are involved in fertilization and amyloid formation processes. In this work, the structure and dynamic behavior of SEM1(45-107) and SEM1(49-107) peptides and their N-domains were described. According to ThT fluorescence spectroscopy data, it was shown that the amyloid formation of SEM1(45-107) starts immediately after purification, which is not observed for SEM1(49-107). Seeing that the peptide amino acid sequence of SEM1(45-107) differs from SEM1(49-107) only by the presence of four additional amino acid residues in the N domain, these domains of both peptides were obtained via solid-phase synthesis and the difference in their dynamics and structure was investigated. SEM1(45-67) and SEM1(49-67) showed no principal difference in dynamic behavior in water solution. Furthermore, we obtained mostly disordered structures of SEM1(45-67) and SEM1(49-67). However, SEM1(45-67) contains a helix (E58-K60) and helix-like (S49-Q51) fragments. These helical fragments may rearrange into β-strands during amyloid formation process. Thus, the difference in full-length peptides' (SEM1(45-107) and SEM1(49-107)) amyloid-forming behavior may be explained by the presence of a structured helix at the SEM1(45-107) N-terminus, which contributes to an increased rate of amyloid formation.

Hydrogen Bonding Compensation on the Convex Solvent-Exposed Helical Face of IA3, an Intrinsically Disordered Protein.

Saccharomyces cerevisiae IA3 is a 68 amino acid peptide inhibitor of yeast proteinase A (YPRA) characterized as a random coil when in solution, folding into an N-terminal amphipathic alpha helix for residues 2-32 when bound to YPRA, with residues 33-68 unresolved in the crystal complex. Circular dichroism (CD) spectroscopy results show that amino acid substitutions that remove hydrogen-bonding interactions observed within the hydrophilic face of the N-terminal domain (NTD) of IA3-YPRA crystal complex reduce the 2,2,2-trifluoroethanol (TFE)-induced helical transition in solution. Although nearly all substitutions decreased TFE-induced helicity compared to wild-type (WT), each construct did retain helical character in the presence of 30% (v/v) TFE and retained disorder in the absence of TFE. The NTDs of 8 different Saccharomyces species have nearly identical amino acid sequences, indicating that the NTD of IA3 may be highly evolved to adopt a helical fold when bound to YPRA and in the presence of TFE but remain unstructured in solution. Only one natural amino acid substitution explored within the solvent-exposed face of the NTD of IA3 induced TFE-helicity greater than the WT sequence. However, chemical modification of a cysteine by a nitroxide spin label that contains an acetamide side chain did enhance TFE-induced helicity. This finding suggests that non-natural amino acids that can increase hydrogen bonding or alter hydration through side-chain interactions may be important to consider when rationally designing intrinsically disordered proteins (IDPs) with varied biotechnological applications.

A heptadeca amino acid peptide subunit of cathelicidin LL-37 has previously unreported antifungal activity.

Yeasts such as Candida albicans, albeit being ubiquitous members of the skin, oral and vaginal microbiome, can cause superficial to life-threatening infections. Human cathelicidin LL-37-based peptides have antibacterial activity and yet, their antifungal activity remains to be thoroughly characterized. The aim of this study was to comprehensively investigate the activity of LL-37-based peptides against C. albicans. LL-37 and its derivatives were tested for their ability to kill C. albicans planktonic cells in the presence of various biological matrices (serum, plasma, saliva and urine), that have been reported to inactivate peptides. The antibiofilm activity, resistance development and biocompatibility were investigated for the lead peptide. GK-17, a 17 amino acid peptide, showed remarkable stability to fungal aspartyl proteases and rapidly killed planktonic C. albicans despite the presence of biological matrices. GK-17 also inhibited adhesion to biotic and abiotic substrates, inhibited biofilm formation and eradicated preformed biofilms in the presence of biological matrices. Compared to nystatin, GK-17 had a lower propensity to allow for resistance development by C. albicans. The peptide showed concentration-dependent biocompatibility to red blood cells, with only 30% hemolysis even at 4× the fungicidal concentration. Taken together, GK-17 is a novel antifungal peptide with promising effects against C. albicans.

Study on the hypolipidemic activity of rapeseed protein-derived peptides

Hyperlipidaemia, a common chronic disease, is the cause of cardiovascular diseases such as myocardial infarction and atherosclerosis. Generally, drugs for lowering blood lipids have disadvantages such as short or poor efficacy, high toxicity, and side effects. Rapeseed active peptides are excellent substitutes for lipid-lowering drugs because of their high biological safety, strong penetration, and easy absorption by the human body. This study separated and purified the rapeseed peptides using gel chromatography and mass spectrometry. Rapeseed peptides amino acid sequences were determined to obtain Glu-Phe-Leu-Glu-Leu-Leu (EFLELL) peptides with good hypolipidaemic activity and IC50 values of 0.1973 ± 0.05 mM (sodium taurocholate), 0.375 ± 0.03 mM (sodium cholate), and 0.203 ± 0.06 mM (sodium glycine cholate). The EFLELL hypolipidaemic activity was evaluated, and its mechanism of action was investigated using cell lines. Rapeseed peptide treatment significantly decreased the total cholesterol (T-CHO), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) levels, and the protein and gene expression levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) and low-density lipoprotein cholesterol (LDLR) suggested the mechanism. Molecular docking revealed that the binding energy between rapeseed peptide and LDLR-PCSK9 molecules was −6.3 kcal/mol and −8.1 kcal/mol. In conclusion, the rapeseed peptide EFLELL exerts a favourable hypolipidaemic effect by modulating the LDLR-PCSK9 signalling pathway.

Investigating the antiviral effect of CLF36 and CLFarm peptide on P32 protein of sheeppox virus through molecular docking simulation

Sheeppox is one of the most common diseases in sheep that can spread quickly in the herd. Currently, there is no specific treatment for this viral disease. The purpose of this study was to investigate the antimicrobial peptide CLF36 and CLFarm on the surface protein of the sheep pox virus P32 protein and the cellular receptors of this protein such as heparin sulfate and UDP-N-acetyl glucosamine. The third structure of P32 was done using software such as I-TASSER. The interactions were performed statically in a computer by bioinformatics tools such as HDOCK software and using Gromacs in the molecular dynamics section. The results of this study showed that the amino acids of CLF36 peptide involved in hydrogen bonding with P32 include D1, K5, V8, Q11, K9, R16, R22, K25, R27 and K34 and for CLFarm include K5, K9, Q11, K13, R27, W30, Q31 and K35. Docking results showed that peptides were attached to three epitope regions EP1,4,8 in P32 protein. In connection with the molecular docking between CLF36 arm and the two receptors UDP-N-acetylglucosamine and heparin sulfate, the hydrogen bonds included Gln 11, Trp 30 and Trp 4, Trp 30, Gln 11, Arg 27, Cys 33, respectively; Although CLF36 had weak binding energy with these two receptors. In the molecular dynamics section, the graph of RMSF and RMSD and Gyrate showed a few fluctuations, which were ignored. Finally, these results showed that both peptides have a good performance against P32 in a period of 50 ns.

Identification of a Bitter Peptide Contributing to the Off-Flavor Attributes of Pea Protein Isolates

The aversive bitter taste of pea protein ingredients limits product acceptability. Compounds contributing to the bitter perception of pea protein isolates were investigated. Off-line multi-dimensional sensory-guided preparative liquid chromatography fractionation of a 10% aqueous PPI solution revealed one main bitter compound that was identified by Fourier transform ion cyclotron resonance mass spectrometry and de novo tandem mass spectrometry (MS/MS) sequencing as the 37 amino acid peptide PA1b from pea albumin and further confirmed by synthesis. Quantitative MS/MS analysis reported that the concentration of the bitter peptide was 129.3 mg/L, which was above the determined bitter sensory threshold value of 3.8 mg/L and in agreement with the perceived bitter taste of the sample.

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The utilization of fluorinated amino acids in antimicrobial peptides (AMPs) is suggested as an effective approach to enhance membrane permeability and, thus, strengthen the non‐specific AMP targeting onto the bacterial envelope. Koksch and co‐workers report on the influence of aliphatic side chain fluorination on the antimicrobial activities of artificial β‐hairpin peptides. Among this work, the AMP SAJO‐PfpGly (“AMP OF THE MONTH”) equipped with two pentafluoro‐alkylated residues was identified as the most potent agent, while owning near to zero values of blood cell hemolysis and cytotoxicity. Its enzyme‐degradability despite the degree of fluorine‐substitution underlines the tremendous perspective tailor‐made fluorinated amino acids bear as orthogonal tool in modern peptide engineering. (doi: 10.1002/pep2.24306) image

Identification of a mitochondrial targeting sequence in cathepsin D and its localization in mitochondria.

Cathepsin D (CTSD) is a major lysosomal protease harboring an N-terminal signal peptide (amino acids 1-20) to enable vesicular transport from endoplasmic reticulum to lysosomes. Here, we report the possibility of a mitochondrial targeting sequence and mitochondrial localization of CTSD in cells. Live-cell imaging analysis with C-terminal enhanced green fluorescent protein-tagged CTSD (EGFP-CTSD) indicated that CTSD localizes to mitochondria. CTSD amino acids 21-35 are responsible for its mitochondrial localization, which exhibit typical features of mitochondrial targeting sequences, and are evolutionarily conserved. A proteinase K protection assay and sucrose gradient analysis showed that a small population of endogenous CTSD molecules exists in mitochondria. These results suggest that CTSD is a dual-targeted protein that may localize in both lysosomes and mitochondria.

SPA4 peptide suppresses the lipopolysaccharide (LPS)-stimulated lactate secretion in lung epithelial cells through modulation of Toll-like receptor-4 (TLR4)

Abstract Lung infection and inflammation can cause severe injury leading to acute respiratory distress syndrome. An increased expression and activity of the TLR4 is associated with inflammatory response. Simultaneous elevated level of lactate is used as the marker of disease severity and is associated with poor outcomes in critically ill patients. Therapeutic treatment with TLR4-interacting SPA4 peptide (amino acid sequence: GDFRYSDGTPVNYTNWYRGE) suppresses inflammation in immune cells and in mouse models of lung infection and inflammation. In this study, we evaluated the effect of SPA4 peptide on lactate production by H441 human lung epithelial cells against Pseudomonas aeruginosa-derived LPS. Briefly, the H441 cells were challenged with LPS (1 μg/ml) and treated with SPA4 peptide (100 μM) after 1 h of LPS challenge. Next day, the cell-free supernatants and cell lysates were harvested. We also transfected the cells with TLR4 siRNA to achieve suppression of TLR4. Levels of protein and lactate were quantitated in cell lysates and in filtered supernatants using biochemical assays. The lactate levels were normalized with cell protein. The unchallenged, vehicle-treated cells served as control. Our results demonstrated reduced secretion of lactate by SPA4 peptide-treated cells (187.5% of control) versus vehicle-treated cells (324.7% of control) against LPS stimuli (p<0.05). The immunostaining and confocal imaging showed knockdown of TLR4 in up to 50% cells. The LPS-stimulated lactate secretion was reduced and SPA4 peptide treatment did not further affect the lactate levels in TLR4 siRNA transfected cells. Together, our results suggest that the SPA4 peptide suppresses lactate secretion through modulation of TLR4 in lung epithelial cells. Supported by grant from NIH (R01HL136325) and 2021 American Association of Immunologists Careers in Immunology Fellowship Program.

A potential role for GPR107 in hypoglycemia unawareness

Hypoglycemia unawareness (HU) is a major barrier to achieving glycemic control in diabetic patients and remains a severe complication for type 1 and many type 2 diabetics. Due to the limited availability of animal models and significant variations between existing models, our understanding is limited regarding the cellular mechanisms and neural pathways responsible for this loss of metabolic control in the setting of recurrent hypoglycemia. Our group has recently identified GPR107 as a receptor for neuronostatin (NST), a 13 amino acid peptide derived from the somatostatin prepro-hormone. In our novel rat model of HU, we show that GPR107 expression is dramatically increased in the hypothalamus of rats exhibiting loss of hypoglycemia-induced food intake. Using a GPR107-flox rat model, we evaluated the effect of loss of GPR107 in the hypothalamus on the development of HU. Our preliminary data indicate that knockdown of hypothalamic GPR107 protects rats against HU induced by exposure to recurrent hypoglycemia. Future work will focus on the mechanisms underlying the role of GPR107 in the development of this dangerous clinical entity. National Institute of Health (NIH) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Protective effect of additional cathelicidin antimicrobial peptide PR-39 on prosthetic-joint infections.

Prosthetic-joint infection (PJI) is one of the severest complications after arthroplasty. However, antibiotics are not effective in the bacteria in biofilm outside the prosthetic-joint. Antimicrobial peptides have an efficient antimicrobial activity in staphylococcus aureus compared with conventional antibiotics. Bone marrow stem cells (BMSCs) were isolated, cultured and transfected with cathelicidins antimicrobial peptides proline-arginine-rich 39 amino acid peptide (PR-39) lentivirus. The expression of PR-39 gene in BMSCs was detected by RT-PCR, and the antibacterial activity of PR-39 was measured by agar diffusion method. The transfection efficiency was detected by fluorescence microscopy. The infection model of artificial knee joint in rabbits were established. Kirschner wire was used as the knee joint implant to implant the distal femur through the femoral intercondylar fossa of rabbits. 24 rabbits were randomly divided into 2 groups for the above operations: group A was inoculated 0.5mL into the joint cavity immediately after the incision was sutured 1 × 107 Staphylococcus aureus of colony forming unit (CFU), group B was inoculated with Staphylococcus aureus and PR-39. After operation, the wound conditions and histological changes were observed by X-ray and optical microscope respectively, CRP and erythrocyte sedimentation rate were measured by test assay. The transfection efficiency of lentivirus vectortransfected BMSCs was 74.09%. The supernatant of lentivirus vector had obvious inhibitory effect on Staphylococcus aureus, and the antibacterial rate was 98.43%. 100% infection observed in group A while few infection observed in group B; serum CRP and ESR at a high level in group A while decreased in group B after operation. There were no significant difference in CRP and ESR between the pLV/PR-39 group and pLV/EGFP group at day 1 and 3 respectively after surgery. However, CRP and ESR in the pLV/PR-39 groupwere significantly lower than the pLV/EGFP group at day 7 and 14 respectively after operation. Rabbits planted BMSCs expressing PR-39 were significantly increased resistance to Staphylococcus aureus in PJI than control group thus showing great potential for preventing implant-associated infection. It will provide a potential new therapeutic agent for implant-associated infection.

SARS-CoV-2 and other Coronaviruses: A matter of variations

Since the appearance of COVID-19 disease as an epidemic and pandemic disease, many studies are performed to uncover the genetic nature of the newly discovered coronavirus with unique clinical features. The last three human coronavirus outbreaks, SARS-CoV, MERS-CoV and SARS-CoV-2 are caused by Beta-Coronaviruses. Horizontal genetic materials transfer was proven from one coronavirus to the other coronavirus of non-human origin like infectious bronchitis virus (IBV) of avian. Horizontal genetic materials transfer was also from non-corona viruses like astroviruses and equine rhinovirus (ERV-2) or from coronavirus-unrelated viruses, like influenza virus type C. However, SARS-CoV-2 is identical to SARS-CoV and MERS-CoV. Interestingly, Wuhan city-SARS-CoV-2 is very similar to two types of bats Coronavirus in RdRp nucleotide sequence to RdRp of SARS-CoV-2 suggesting possible transmission from bats. Moreover, many genomic mutations are found in SARS-CoV-2 genomes suggesting the mutations are developed and the virus is constantly changed. The newly discovered SARS-CoV-2 has a new open reading frame (ORF) that encodes for thirty-eight amino acid peptide chains and has no similar sequence in all reported NCBI data regarding respiratory viruses. The short peptide can serve as an identification target for SARS-CoV-2 detection.