Chymotrypsin inhibitors from hemolymph of the silkworm, Bombyx mori

Bioavailability of orally administered rhGM-CSF: a single-dose, randomized, open-label, two-period crossover trial

Background

Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) is usually administered by injection, and its oral administration in a clinical setting has been not yet reported. Here we demonstrate the bioavailability of orally administered rhGM-CSF in healthy volunteers. The rhGM-CSF was expressed in Bombyx mori expression system (BmrhGM-CSF).

Methods and Findings

Using a single-dose, randomized, open-label, two-period crossover clinical trial design, 19 healthy volunteers were orally administered with BmrhGM-CSF (8 µg/kg) and subcutaneously injected with rhGM-CSF (3.75 µg/kg) respectively. Serum samples were drawn at 0.0h, 0.5h ,0.75h,1.0h,1.5h,2.0h ,3.0h,4.0h,5.0h,6.0h,8.0h,10.0h and 12.0h after administrations. The hGM-CSF serum concentrations were determined by ELISA. The AUC was calculated using the trapezoid method. The relative bioavailability of BmrhGM-CSF was determined according to the AUC ratio of both orally administered and subcutaneously injected rhGM-CSF. Three volunteers were randomly selected from 15 orally administrated subjects with ELISA detectable values. Their serum samples at the 0.0h, 1.0h, 2.0h, 3.0h and 4.0h after the administrations were analyzed by Q-Trap MS/MS TOF. The different peaks were revealed by the spectrogram profile comparison of the 1.0h, 2.0h, 3.0h and 4.0h samples with that of the 0.0h sample, and further analyzed using both Enhanced Product Ion (EPI) scanning and Peptide Mass Fingerprinting Analysis. The rhGM-CSF was detected in the serum samples from 15 of 19 volunteers administrated with BmrhGM-CSF. Its bioavailability was observed at an average of 1.0%, with the highest of 3.1%. The rhGM-CSF peptide sequences in the serum samples were detected by MS analysis, and their sizes ranging from 2,039 to 7,336 Da.

Conclusions

The results demonstrated that the oral administered BmrhGM-CSF was absorbed into the blood. This study provides an approach for an oral administration of rhGM-CSF protein in clinical settings.

Trial Registration

www.chictr.orgChiCTR-TRC-00000107

Purification, Characterization and Cloning of a Chymotrypsin Inhibitor (CI-9) from the Hemolymph of the Silkworm, Bombyx mori

Hemolymph chymotrypsin inhibitor 9 (CI-9) from the hemolymph of the silkworm, Bombyx mori, was purified by ammonium sulfate precipitation, Butyl Toyopearl hydrophobic chromatography, gel filtration through Sephadex C-50 and chymotrypsin-sepharose 4B affinity chromatography. Checked by Native PAGE and SDS-PAGE in combination with silver staining, the final preparation appeared homogeneous. In tricine SDS-PAGE, CI-9 displayed a molecular weight of 7.5 kD, which was determined to be 7167 Da with the Voyager TOFMass analyser. The pI value for CI-9, revealed by 2D-PAGE (two-dimensional polyacrylamide gel electrophoresis), was 4.3. CI-9 exhibited inhibitory activity at a temperature as high as 100 degrees C and a stability against a wide range of pH (1-12). In N-terminal amino-acid analysis of CI-9, 40 amino acid residues were obtained. The C-terminal 22 amino acid residues were deduced by subsequently cloned cDNA and genomic fragments. MW and pI of CI-9 were predicted to be 7170.98 Da and 4.61, respectively, on the website. Its low molecular weight, high stability, conserved active site and Kunitz domain showed that CI-9 is a Kunitz-type CI. The difference of sequence and pI between CI-9 and other Kunitz type CIs indicated that it is a novel chymotrypsin inhibitor.

Can 29kDa rhGM-CSF expressed by Silkworm pupae bioreactor bring into effect as active cytokine through orally administration?

In order to study the effect of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) as active cytokine through orally administration, we expressed hGM-CSF within silkworm pupae bioreactor. The purified rhGM-CSF named as BmrhGM-CSF is characterized as 29kDa glycoprotein, and its biological activity was measured both in vitro and in vivo. We found out BmrhGM-CSF could stimulate the colony formation of human bone marrow cells in a dose-dependent manner whether which were treated with or without gamma-ray 24h before. The ability of colony formation induced by BmrhGM-CSF is negatively correlated with gamma-ray intensity. As soon as 15min post oral administration with BmrhGM-CSF labeled with (125)I, an approximately 20kDa protein fragment was detected within mice blood by SDS-PAGE followed by autoradiography. In blood sample of test mice, a protein was also recognized by anti-hGM-CSF antibody using ELISA. The immunohistochemical analysis showed that BmrhGM-CSF was detected within intestinal histiocyte. This indicated it might be absorbed into blood via intestinal microvillus. Pharmacokinetics analysis after orally administered BmrhGM-CSF in animal model of leucopenia including mice, Beagle dogs and macaques showed that: (1) BmrhGM-CSF promoted the CFU-S formation in mice spleen and the synthesis of DNA in bone marrow cells of mice; (2) BmrhGM-CSF induced bone marrow karyocyta granulocyte growth significantly in both macaques and Beagle dogs compared to the negative control group. On the 9th day of orally administration, the animal WBC significantly increased in a dose-dependant manner, in which neutrophilic granulocyte was predominant. The WBC level of dogs in high dose group was about 1.5x10(9)cells/L more than that in the negative control. And the bone marrow smear revealed that the percents of both myloblast and progranulocyte in WBC in the hGM-CSF group were obviously higher than those in the negative control. These results proved that BmrhGM-CSF, a 29kDa glycoprotein expressed by Silkworm pupae bioreactor, could bring into the effect as active cytokine through oral administration.

Protein purification, cDNA cloning and characterization of a protease inhibitor from the Indian tasar silkworm, Antheraea mylitta

An inhibitor of Aspergillus oryzae fungal protease was purified to homogeneity from the hemolymph of fifth instar larvae of Antheraea mylitta by ammonium sulfate precipitation, anion exchange and gel filtration (FPLC) chromatography, and termed as AmFPI-1. The extent of purification was checked by two-dimensional gel electrophoresis, and the molecular weight of purified inhibitor was determined by SDS-PAGE as 10.4 kDa. Fifteen N-terminal amino acid sequences of this protein were determined, and degenerate oligonucleotides were synthesized on the basis of these sequences. A cDNA library of A. mylitta integument was constructed, and protease inhibitor cDNA was partially amplified by PCR using degenerate oligonucleotides and CDS primers. A full-length inhibitor cDNA clone obtained by screening the library with PCR amplified DNA as probe was sequenced. The cDNA consists of 543 nucleotides with an ORF of 315 bp and encodes a protein of 105 amino acids. The sequence exhibits similarity to several Bombyx mori ESTs, and in particular to N-terminal amino acid sequence of an inducible serine protease inhibitor (ISPI-1) from Galleria mellonella indicating its relatedness to ISPI-1 of G. mellonella. The presence of this protease inhibitor in the hemolymph may play an important role as a natural defense system against invading microorganisms.

Mamestra configurata serpin-1 homologues: cloning, localization and developmental regulation

A screen of a Mamestra configurata (bertha armyworm) midgut cDNA library identified three types of cDNA clones that resemble the Manduca sexta serpin-1 gene family. Two serpins, 1b and 1c, possess a common conserved serpin amino terminal scaffold domain but bear no similarity to any members of the M. sexta gene family within the reactive centre loop. These serpins differ from one another by only two amino acids in the reactive centre loop (S(363)-->P) and serpin signature (M(369)-->T) regions. The other member, denoted serpin-1a, is closely related to the M. sexta serpin-1Z. M. configurata serpins as a group were expressed in all insect developmental stages including eggs, larvae and adult moths. Within larvae, serpin gene expression was restricted to the early to middle instar developmental phase and mainly in the fat body and hemocytes. Stress imposed by starvation strongly induced expression in fat body and to a lesser degree in alimentary organs, nervous system and Malphigian tubules. Conversely, starvation decreased expression in hemocytes. Wounding or inoculation with bacteria did not induce serpin gene transcription but did lead to the formation of higher and lower molecular weight forms, presumably serpin-protease complexes and resultant truncated serpin, respectively. Two dimensional PAGE and western blotting analysis revealed at least 12 distinct serpins consisting primarily of neutral, but also highly acidic and basic isoforms, as well as additional high and low molecular weight immuno-reactive species. Serpins-1b/1c are the more prominent serpin isoforms and are expressed predominantly in the fat body and subsequently exported to the hemolymph as revealed by western blotting and immunolocalization. The serpin-1b/1c isoform was found only as the fully glycosylated species within the hemolymph. Hemolymph protease activity was comprised mostly of serine proteases whose overall activity increased dramatically at the onset of the molt concomitant with a sharp decline in serpin gene expression.

Identification of four small molecular mass proteins in the silk of Bombyx mori

This paper describes cDNAs of four small-size proteins that occur in the cocoon silk of Bombyxmori. Two of them (9.9 and 10.3 kDa), which have the N-terminal sequences and the spacing of a few amino acids at C-termini similar to the seroin of Galleria mellonella, are called seroin 1 and seroin 2. The corresponding genes are expressed in the middle, and to a small extent also in the posterior silk gland sections. The seroin 1 and less conspicuously the seroin 2 mRNAs accumulate in the course of the last larval instar to a maximum in postspinning larvae. Two other proteins (6 kDa and 4.7 kDa) of B. mori cocoons were identified as a typical Kunitz-type and a somewhat unusual Kazal-type proteinase inhibitors, and named BmSPI 1 and BmSPI 2, respectively. Their genes are expressed in the middle, and the BmSPI 1 gene slightly also in the posterior silk gland sections. The expression ensues a few days after the last larval ecdysis and increases until the cocoon spinning. Post-spinning larvae still contain high amounts of the BmSPI 1 but no BmSPI 2 transcripts. It is assumed that seroins and proteinase inhibitors are involved in cocoon protection against predators and microbes.

Synthesis and resorption of a humoral chymotrypsin inhibitor, CI-8, by fat body of the silkworm, Bombyx mori

The Bombyx mori hemolymph contains up to 16 chymotrypsin inhibitors (CIs). The present in vitro culture of tissues in Grace's medium indicated that CI-8, which belongs to the largest molecular-size group of CIs with sugar moiety, is synthesized in the fat body and secreted from it during the feeding period. When the fat body from other strain which synthesizes an allelic component (CI-7) instead of CI-8 was incubated in vitro in hemolymph from the strain which has CI-8, the fat body was found to receive CI-8. Thus it was concluded that CI-8, once secreted into the hemolymph, was again sequestered into the fat body after the onset of spinning. Protein granules isolated from the pupal fat body were shown to contain CI-8, indicating that the sequestered CI-8 is present in the protein granules.

Isolation and characterization of novel inducible serine protease inhibitors from larval hemolymph of the greater wax moth Galleria mellonella

Three inducible serine protease inhibitors (ISPI-1, 2, 3) have been purified from larval hemolymph of greater wax moth larvae, Galleria mellonella, and characterized at a molecular level. These inhibitors were synthesized after larvae were injected with a yeast polysaccharide, zymosan preparation. ISPI-1,2,3 were active against various serine proteases including trypsin and toxic proteases released by the entomopathogenic fungus Metarhizium anisopliae. Precipitation by trichloroacetic acid and heat, followed by FPLC and HPLC separation steps were used for purification of the protease inhibitors from cell-free hemolymph samples. The molecular masses of purified proteins were determined by MS to be 9.2 kDa (ISPI-1), 6.3 kDa (ISPI-2) and 8.2 kDa (ISPI-3) with isoelectric points ranging between 7.2 and 8.3. The N-terminal amino-acid sequences of ISPI-1 and ISPI-3 are not similar to other known proteins, whereas that of ISPI-2 exhibits extensive similarity to known Kunitz-type protease inhibitors.

Primary structure and possible functions of a trypsin inhibitor of Bombyx mori

A protein with a low molecular mass of 6027 was purified from cocoon shell of silkworm, Bombyx mori. Two-dimensional polyacrylamide gel electrophoresis (2D/PAGE) resolved this protein into a single spot with pI 4.3 and Mr 6000. Amino acid sequence analysis revealed that this protein consists of 55 amino acids, six of these being cysteine residues and is highly homologous to bovine pancreatic trypsin inhibitor-type inhibitors. The 6-kDa protein is heat stable and acid stable and inhibits bovine trypsin by forming a low-dissociation complex with trypsin in a 1 : 1 molar ratio (Ki = 2.8 x 10-10), but does not alpha-chymotrypsin. This cocoon shell-associated trypsin inhibitor (CSTI) was thus concluded to belong to the bovine pancreatic trypsin inhibitor class. CSTI was developmentally regulated in the silk gland at the final stage of larval growth, and its specific distribution in the middle silk gland, an organ in which silk proteins are stored during the final larval instar, occurred before the onset of spinning. This inhibitor protects the tryptic degradation of fibroin light (L) chain in vitro. These results suggest that this trypsin inhibitor may play an important part on regulating proteolytic activity in the silk gland or protecting silk proteins from degradation during histolysis.

Protein protease inhibitors in insects and comparison with mammalian inhibitors

1. Studies on insect protein protease inhibitors are summarized. Biochemical, genetic and physiological investigations of the silkworm are performed. 2. In addition, the properties and characteristics of fungal protease inhibitors from the silkworm (Bombyx mori) are described and their importance as defensive functions is emphasized. 3. This review also concerns comparative and evolutionary studies of protease inhibitors from various sources. 4. The biological significance of inhibitors is discussed in view of the extensive experimental results.

Serine proteinase inhibitor profiles in the hemolymph of a wide range of insect species

1. The inhibition of trypsin, chymotrypsin, neutrophil elastase and cathepsin G, and pancreatic elastase by the hemolymph of 14 insect species in six orders has been investigated. 2. All samples showed great diversity in terms of both total proteinase inhibitory capacity and specificity. 3. The highest total inhibitory capacity was found in the larval hemolymph of species in the beetle family Tenebrionidae and the lowest in that of an adult coreid bug, Acanthocephala femorata.

Amino-acid sequences of two basic chymotrypsin inhibitors from silkworm larval hemolymph

Amino-acid sequences of two basic chymotrypsin inhibitors from silkworm hemolymph (SCI-I and SCI-II) are determined. They are composed of each 62 amino-acid residues with differences in only two positions to each other. They both contain six half cystines in a similar arrangement as that of Kunitz-type proteinase inhibitor, except for the one amino-acid insertion in the first cysteine frame. The inhibitory activity of SCI-II against trypsin should be attributed to Lys44 displacing Gln44 in SCI-I which has no antitryptic activity.

Purification and characterization of a high-Mr proteinase inhibitor of pro-phenol oxidase activation from crayfish plasma

Crayfish plasma was found to contain a proteinase inhibitor, which was purified to apparent homogeneity by acid precipitation, affinity chromatography on concanavalin A-Sepharose and hydrophobic-interaction chromatography. The inhibitor is a monomeric protein with an Mr of about 155,000 and a pI in the range 4.6-4.8. It is heat-stable and tolerant to low pH. It inhibits the serine proteinases trypsin and chymotrypsin, but not thrombin or subtilisin. Furthermore, it is efficient in decreasing the activity of a proteinase from crayfish haemolymph that is involved in the activation cascade of pro-phenol oxidase and can also block pro-phenol oxidase activation by this serine proteinase. This cascade is believed to play a central role in the recognition mechanism of non-self material in crustaceans and insects. The data presented give some evidence that the new proteinase inhibitor is involved in the regulation of this system.

Genetic variants of protease inhibitors against fungal protease and alpha-chymotrypsin from hemolymph of the silkworm, Bombyx mori

Many electrophoretic variants of hemolymph inhibitors of proteases from Aspergillus melleus and pancreatic alpha-chymotrypsin were found using 126 silkworm strains. Six inhibitors of the fungal protease were detected and eight of chymotrypsin; the distribution of inhibitors among Japanese, Chinese, and European races was investigated. Comparison of electrophoretic patterns from F1 hybrids and parents showed that the offspring produce inhibitors of both parental types. Segregation in F2 and backcrossing suggest that the expression of each inhibitor is controlled in most cases by a pair of alleles which are responsible for strong and null bands. Two bands of fungal protease inhibitors C and D were controlled by codominant alleles. These results suggest that polymorphism of hemolymph protease inhibitors in the silkworm would be a useful experimental system for the study of the genetic control of protease inhibitors.

Properties of protease inhibitors from the haemolymph of silkworms, Bombyx mori, Antheraea pernyi and Philosamia cynthia ricini

1. Effects of inhibitors in the haemolymph from three silkworms on proteases from the alimentary canal of respective insects were studied as well as those on bovine trypsin and alpha-chymotrypsin. 2. In Bombyx haemolymph, three inhibitor fractions were separated by gel filtration on Sephadex G-75. These fractions differed in the specificity of inhibition for different proteases and in thermal stability. 3. In Antheraea haemolymph, a relatively different elution profile was observed compared to that of Bombyx. Philosamia haemolymph showed the intermediate type of elution pattern. 4. Inhibitors from the haemolymph of Antheraea and Philosamia were heat stable. 5. Distinct electrophoretic patterns of inhibitors were observed in three silkworms.

Isolation and properties of a chymotrypsin inhibitor from winged bean seed (Psophocarpus tetragonolobus (L) Dc.)

A new inhibitor of bovine alpha-chymotrypsin has been isolated from winged bean seed. The inhibitor was purified to homogeneity by affinity chromatography on chymotrypsin-Sepharose, following the removal of the trypsin inhibitors on trypsin-Sepharose. The inhibitor has a molecular weight of approx. 21,000 and amino acid analysis showed that it contains four half-cystine residues, lacks methionine, and is rich in aspartic acid, glutamic acid, valine and leucine. The inhibitor does not inhibit bovine trypsin in the standard inhibitor assay and does not bind to trypsin-Sepharose at ph 8.0. Inhibition data show that 1 mol of inhibitor inhibits 2 mol of alpha-chymotrypsin to form a 1:2 complex. The inhibition, however, is characterized by substrate induced dissociation of the complex and complete inhibition, even at high inhibitor concentration, is not attained. The inhibitor-chymotrypsin complex is stable at pH 8.0 and was isolated by gel-filtration on Sephadex G-100. An apparent molecular weight of approx. 70,000 was obtained for the complex, measured by gel filtration and ultracentrifugal analysis, consistent with a 1:2 molar stoichiometry.