Apidaecins are cationic, proline-rich antimicrobial peptides originally isolated from honeybees and exhibit high Gram-negative activity by inhibiting bacterial protein translation. Pharmacokinetics ...of apidaecin derivative Api137 was studied using single and multiple intravenous or subcutaneous injections as well as continuous subcutaneous infusion and correlated to its efficacy in a lethal murine
Escherichia coli
infection model. Survival rates of infected CD-1 mice were monitored and Api137 and its metabolites were quantified in plasma of uninfected CD-1 mice and Sprague Dawley rats using reversed-phase chromatography coupled online to mass spectrometry. The highest Api137 plasma levels of 23 mg/L were obtained after a single intravenous injection of 20 mg/kg body weight, which declined fast over the next 120 min (half-life time < 30 min). In contrast, continuous subcutaneous infusion of a similar dose over an hour (19.2 mg/kg/h) lead to stable plasma levels of ∼6 mg/L, which was above the minimal inhibitory concentration against
E. coli
ATCC 25922 (4 mg/L). The increased exposure by continuous subcutaneous administration of Api137 at 19.2 mg/kg/h over 48 h improved efficacy in the murine intraperitoneal sepsis model with survival rates of 67% over 5 days compared to 33% after intravenous and subcutaneous administration in different dosing schemes. To the best of our knowledge, continuous subcutaneous infusion using osmotic pumps was successfully utilized for delivery of an antimicrobial peptide for the first time. Additionally, the potential of apidaecin analogs as novel antibiotics is demonstrated even in a scenario where the infection site is clearly separated from the route of administration.
A variety of molecules in human blood have been implicated in the inhibition of HIV-1. However, it remained elusive which circulating natural compounds are most effective in controlling viral ...replication in vivo. To identify natural HIV-1 inhibitors we screened a comprehensive peptide library generated from human hemofiltrate. The most potent fraction contained a 20-residue peptide, designated VIRUS-INHIBITORY PEPTIDE (VIRIP), corresponding to the C-proximal region of α1-antitrypsin, the most abundant circulating serine protease inhibitor. We found that VIRIP inhibits a wide variety of HIV-1 strains including those resistant to current antiretroviral drugs. Further analysis demonstrated that VIRIP blocks HIV-1 entry by interacting with the gp41 fusion peptide and showed that a few amino acid changes increase its antiretroviral potency by two orders of magnitude. Thus, as a highly specific natural inhibitor of the HIV-1 gp41 fusion peptide, VIRIP may lead to the development of another class of antiretroviral drugs.
We report the isolation and characterization of a novel human peptide with antimicrobial activity, termed LEAP-1 (liver-expressed antimicrobial peptide). Using a mass spectrometric assay detecting ...cysteine-rich peptides, a 25-residue peptide containing four disulfide bonds was identified in human blood ultrafiltrate. LEAP-1 expression was predominantly detected in the liver, and, to a much lower extent, in the heart. In radial diffusion assays, Gram-positive
Bacillus megaterium,
Bacillus subtilis,
Micrococcus luteus,
Staphylococcus carnosus, and Gram-negative
Neisseria cinerea as well as the yeast
Saccharomyces cerevisiae dose-dependently exhibited sensitivity upon treatment with synthetic LEAP-1. The discovery of LEAP-1 extends the known families of mammalian peptides with antimicrobial activity by its novel disulfide motif and distinct expression pattern.
Introduction
PRI‐002 is an orally available anti–amyloid beta (Aβ) prionic compound developed for direct disassembly of toxic Aβ oligomers relevant to Alzheimer's disease.
Methods
Two ...placebo‐controlled clinical phase I trials with oral dosing of PRI‐002 were conducted in healthy young subjects: A single ascending dose trial (4, 12, 36, 108, or 320 mg PRI‐002 or placebo) in 40 participants followed by a multiple ascending dose study with daily 160 mg PRI‐002 for 14 days or 320 mg for 28 days in 24 participants. The main objectives were safety, tolerability, and evaluation of pharmacokinetic (PK) parameters.
Results
PRI‐002 was safe and well tolerated after single and multiple oral administration up to the highest doses. PRI‐002 was absorbed rapidly and drug exposure increased proportional to dose. During repeated daily administration, the drug accumulated by a factor of about three. Steady‐state conditions were reached after 1 to 2 weeks.
Conclusions
The safety and PK results encourage further clinical development of PRI‐002.
The human genome contains numerous genes whose protein products are unknown in terms of structure, interaction partner, expression, and function. To unravel the function of these orphan genes, it is ...of particular value to isolate native forms of protein and peptide products derived from these genes. From human blood ultrafiltrate, we characterized a novel gene‐encoded, cysteine‐rich, and cationic peptide that we termed liver‐expressed antimicrobial peptide 2 (LEAP‐2). We identified several circulating forms of LEAP‐2 differing in their amino‐terminal length, all containing a core structure with two disulfide bonds formed by cysteine residues in relative 1–3 and 2–4 positions. Molecular cloning of the cDNA showed that LEAP‐2 is synthesized as a 77‐residue precursor, which is predominantly expressed in the liver and highly conserved among mammals. This makes it a unique peptide that does not exhibit similarity with any known human peptide regarding its primary structure, disulfide motif, and expression. Analysis of the LEAP‐2 gene resulted in the identification of an alternative promoter and at least four different splicing variants, with the two dominating transcripts being tissue‐specifically expressed. The largest native LEAP‐2 form of 40 amino acid residues is generated from the precursor at a putative cleavage site for a furin‐like endoprotease. In contrast to smaller LEAP‐2 variants, this peptide exhibited dose‐dependent antimicrobial activity against selected microbial model organisms. LEAP‐2 shares some characteristic properties with classic peptide hormones and it is expected that the isolation of this novel peptide will help to unravel its physiological role.
There is evidence that proopiomelanocortin (POMC)-derived peptides other than ACTH are involved in pituitary-dependent adrenal growth. We have synthesized the human N-terminal POMC fragment 1-28-POMC ...with the disulfide bridges in the correct position between cysteine residues 2–24 and 8–20 and studied the activity of these peptides in adrenocortical tumor cells in vitro. 1-28-POMC stimulated cell proliferation in human NCI-h295 and mouse Y-1 adrenal cancer cell lines and also in primary cultures of bovine adrenocortical cells in a concentration-dependent manner. 1-28-POMC led to rapid activation of the MAPKs extracellular signal-regulated kinases-1 and -2, but not c-Jun N-terminal kinase and p38, pathways. Steroid hormone production (cortisol, 17-hydroxyprogesterone, and dehydroepiandrosterone sulfate) in NCI-h295 cells was decreased by 1-28-POMC in a concentration-dependent fashion. However, protein levels of important regulators of steroidogenesis steroidogenic factor-1, DAX-1 (dosage-sensitive sex reversal-adrenal hypoplasia congenita critical region on the X-chromosome 1), steroidogenic acute regulatory protein, and cytochrome P450 side-chain cleavage enzyme remained unaffected by 1-28-POMC treatment. Our results provide evidence that synthetic 1-28-POMC induces adrenal tumor cell proliferation, inhibits adrenal steroidogenesis, and mediates its action by signaling via the extracellular signal-regulated kinase pathway. The distinct roles of 1-28-POMC and ACTH in the regulation of adrenal growth and steroidogenesis suggest that the adrenal cortex is under the dual opposing control of fragments from the same mother peptide POMC.
Members of the Ly-6/uPAR protein family share one
or several repeat units of the Ly-6/uPAR domain that is
defined by a distinct disulfide bonding pattern between
8 or 10 cysteine residues. The ...Ly-6/uPAR protein family
can be divided into two subfamilies. One comprises GPI-anchored
glycoprotein receptors with 10 cysteine residues. The other
subfamily includes the secreted single-domain snake and
frog cytotoxins, and differs significantly in that its
members generally possess only eight cysteines and no GPI-anchoring
signal sequence. We report the purification and structural
characterization of human SLURP-1 (secreted mammalian Ly-6/uPAR
related protein 1) from blood and urine peptide libraries.
SLURP-1 is encoded by the ARS (component B)-81/s locus,
and appears to be the first mammalian member of the Ly-6/uPAR
family lacking a GPI-anchoring signal sequence. A phylogenetic
analysis based on the SLURP-1 primary protein structure
revealed a closer relationship to the subfamily of cytotoxins.
Since the SLURP-1 gene maps to the same chromosomal region
as several members of the Ly-6/uPAR subfamily of glycoprotein
receptors, it is suggested that both biologically distinct
subfamilies might have co-evolved from local chromosomal
duplication events.
Parathyroid hormone (PTH) is involved in regulation of the calcium level in blood and has an influence on bone metabolism, thus playing a role in osteoporosis therapy. In this study, the structures ...of the human PTH fragments (1–34) and (1–39) as well as bovine PTH(1–37) in aqueous buffer solution under near physiological conditions were determined using two-dimensional nuclear magnetic resonance spectroscopy. The overall structure of the first 34 amino acids of these three peptides is virtually identical, exhibiting a short NH2-terminal and a longer COOH-terminal helix as well as a defined loop region from His14 to Ser17, stabilized by hydrophobic interactions. bPTH(1–37), which has a higher biological activity, shows a better-defined NH2-terminal part. In contrast to NH2-terminal truncations, which cause destabilization of helical structure, neither COOH-terminal truncation nor elongation significantly influences the secondary structure. Furthermore, we investigated the structure of hPTH(1–34) in 20% trifluoroethanol solution. In addition to its helix-stabilizing effect, trifluorethanol causes the loss of tertiary hydrophobic interactions.
Sexual intercourse is the major route of HIV transmission. To identify endogenous factors that affect the efficiency of sexual viral transmission, we screened a complex peptide/protein library ...derived from human semen. We show that naturally occurring fragments of the abundant semen marker prostatic acidic phosphatase (PAP) form amyloid fibrils. These fibrils, termed Semen-derived Enhancer of Virus Infection (SEVI), capture HIV virions and promote their attachment to target cells, thereby enhancing the infectious virus titer by several orders of magnitude. Physiological concentrations of SEVI amplified HIV infection of T cells, macrophages, ex vivo human tonsillar tissues, and transgenic rats in vivo, as well as
trans-HIV infection of T cells by dendritic or epithelial cells. Amyloidogenic PAP fragments are abundant in seminal fluid and boost semen-mediated enhancement of HIV infection. Thus, they may play an important role in sexual transmission of HIV and could represent new targets for its prevention.
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