Biochemical, immunological and kinetic characterization and partial sequence analysis of a thiol proteinase inhibitor from Bubalus bubalis kidney: An attempt targeting kidney disorders.

In the present study a thiol proteinase inhibitor was isolated from buffalo kidney making use of ammonium sulphate precipitation and gel filtration chromatography on Sephacryl S-100HR column. Purified inhibitor is homogeneous as it displayed a single band in gel electrophoresis both under reducing and non-reducing environment and is of 65KDa as revealed by gel filtration and SDS PAGE. Kinetic studies revealed the presence of reversible accompanied with competitive mode of inhibition; showing maximum efficacy against papain (Ki=2.90×10-4). It was maximally active at pH 8.0 and was stable for a period of 30, 60 and 90 days at 37, 4 and -20°C respectively. Immunological studies confirmed its purity of epitopes as a single precipitin line is obtained in immunodiffusion. N-terminal analysis revealed that it shared a good homology with mouse kidney cystatin as well as with Human Cys C and Cys E thereby advocating its use as a model for various human oriented studies which targets how the kidney cystatin level varies in accordance with various drugs that are currently being used as a target for variety of diseases.

A nematode immunomodulator suppresses grass pollen-specific allergic responses by controlling excessive Th2 inflammation.

Helminth parasites modulate the immune system by complex mechanisms to ensure persistence in the host. Released immunomodulatory parasite components lead to a beneficial environment for the parasite by targeting different host cells and in parallel to a modulation of unrelated inflammatory responses in the host, such as allergy. The aim of this study was to investigate the effect of the potent helminth immunomodulator, filarial cystatin, in a murine model of airway inflammation and hyperreactivity induced by a clinically relevant aeroallergen (timothy grass (Phleum pratense) pollen) and on the function of peripheral blood mononuclear cells (PBMCs) from timothy grass pollen allergic patients. BALB/c mice were systemically sensitised with a recombinant major allergen of timothy grass pollen (rPhl p 5b) and then challenged with timothy grass pollen extract (GPE) via the airways. Filarial cystatin was applied i.p. during the sensitisation phase. Airway hyperresponsiveness to methacholine challenges, inflammation of airways, inflammatory cell recruitment, cytokine production and lung histopathology were investigated. In a translational approach, PBMCs from allergic subjects and healthy controls were treated in vitro with cystatin prior to stimulation with GPE. Administration of filarial cystatin suppressed rPhl p 5b-induced allergen-specific Th2-responses and airway inflammation, inhibited local recruitment of eosinophils, reduced levels of allergen-specific IgE and down-regulated IL-5 and IL-13 in the bronchoalveolar lavage (BAL). Ex vivo restimulation with cystatin of spleen cells from cystatin-treated mice induced the production of IL-10, while cystatin inhibited allergen-specific IL-5 and IL-13 levels. Human PBMCs from timothy grass pollen allergic patients displayed a shift towards a Th1 response after treatment with cystatin. These results show that filarial cystatin ameliorates allergic inflammation and disease in a clinically relevant model of allergy. This data indicate that filarial cystatin has a modulatory effect on grass pollen-specific responses warranting further investigation of potential preventive and therapeutic options in the treatment of allergies.

Detailed biochemical characterization of human placental cystatin (HPC).

A low molecular weight thiol protease inhibitor (12,500) purified from human placenta has been characterized in detail. Human placental cystatin (HPC) was found to be stable in the pH range 3.0-9.0 and temperature stability was between 40 and 100 degrees C. It does not have any disulphide groups and carbohydrate content. There was no cross-reaction between anti-HPC serum and other purified cystatins like HMW kininogens isolated from sheep plasma and phytocystatins isolated from Phaseolus mungo. The kinetics of inhibition of HPC was studied with ficin and bromelain and the comparison was made with our already reported results with papain. The respective K(i) values obtained for ficin and bromelain are 8.4 x 10(-8) M and 9.5 x 10(-8) M, respectively, whereas the value for papain was 5.5 x 10(-8) M. The values of association constants (K(ass)) for ficin and bromelain were 2.9 x 10(3) and 8.6 x 10(2) M(-1) s(-1), respectively, however, the value for papain was 3.4 x 10(4) M(-1) s(-1), the respective dissociation constant values for ficin and bromelain were 2.6 x 10(-5) and 2.1 x 10(-5) s(-1), respectively, and the value obtained for papain was 2.3 x 10(-5) s(-1). These kinetic parameters taken together along with t(1/2) values and IC(50) values imply that HPC binds more effectively to papain, then ficin and least with bromelain. Far-UV-CD analysis shows that HPC has 21.08% alpha-helical structure and significant amount of beta structure. Near-UV-CD spectra of HPC show positive peak at 280 nm indicating significant amount of tertiary interactions. The partial amino acid sequence analysis shows that HPC has highest sequence homology with chicken cystatin and Gly residue is present at position 11 rather than at conserved position 9, which has also been reported for human stefin A structure. The hydropathy plot of 1-30 amino acid residues shows that most amino acids of this stretch are present in the hydrophobic core of the protein. Owing to low molecular weight, absence of disulphide bonds and carbohydrate content HPC can be placed in type I cystatin family with some resemblance to chicken cystatin as shown by CD studies and amino acid sequence analysis.

Sequence of the proteinase-inhibitor cystatin homologue from the pollen of Ambrosia artemisiifolia (short ragweed).

The nucleotide sequence of a cDNA (designated IPC1/5) encoding a cystatin (Cyt) proteinase-inhibitor homologue from short ragweed (Ambrosia artemisiifolia) pollen was determined and compared to other plant and animal Cyt. The absence of disulfide bonds in the predicted translation product of the IPC1/5 sequence suggests that it most resembles family-I members of the Cyt superfamily. Significant amino acid (aa) sequence identity was found when comparing the translated sequence of IPC1/5 to rice seed Cyt, human keratocyte Cyt A and human liver Cyt B.