Kiwifruit Actinidin: A Proper New Collagenase for Isolation of Cells from Different Tissues

Plant and Arthropod IgE-Binding Papain-like Cysteine Proteases: Multiple Contributions to Allergenicity

Papain-like cysteine proteases are widespread and can be detected in all domains of life. They share structural and enzymatic properties with the group's namesake member, papain. They show a broad range of protein substrates and are involved in several biological processes. These proteases are widely exploited for food, pharmaceutical, chemical and cosmetic biotechnological applications. However, some of them are known to cause allergic reactions. In this context, the objective of this review is to report an overview of some general properties of papain-like cysteine proteases and to highlight their contributions to allergy reactions observed in humans. For instance, the literature shows that their proteolytic activity can cause an increase in tissue permeability, which favours the crossing of allergens through the skin, intestinal and respiratory barriers. The observation that allergy to PLCPs is mostly detected for inhaled proteins is in line with the reports describing mite homologs, such as Der p 1 and Der f 1, as major allergens showing a frequent correlation between sensitisation and clinical allergic reactions. In contrast, the plant food homologs are often digested in the gastrointestinal tract. Therefore, they only rarely can cause allergic reactions in humans. Accordingly, they are reported mainly as a cause of occupational diseases.

Oxidative modification of collagen by malondialdehyde in porcine skin

Human skin is exposed to various physical and chemical stress factors, which commonly cause the oxidation of lipids and proteins. In this study, azo initiator AAPH [2,2' -azobis(2-methylpropionamidine) dihydrochloride] was employed to initiate lipid peroxidation in porcine skin as an ex vivo model for human skin. We demonstrate that malondialdehyde (MDA), a secondary product of lipid peroxidation, is covalently bound to collagen in the dermis, forming MDA-collagen adducts. The binding of MDA to collagen results in an unfolding of the collagen triple helix, formation of the dimer of α-chains of collagen, and fragmentation of the collagen α-chain. It is proposed here that the MDA is bound to the lysine residues of α-chain collagen, which are involved in electrostatic interaction and hydrogen bonding with the glutamate and aspartate of other α-chains of the triple helix. Our data provide crucial information about the MDA binding topology in the skin, which is necessary to understand better the various types of skin-related diseases and the aging process in the skin under stress.

Kiwi extract-incorporated poly(ɛ-caprolactone)/cellulose acetate blend nanofibers for healing acceleration of burn wounds

Kiwi extract (KE) including different components such as quercetin, vitamins C and E, and actinides has been known as a debridement agent for burn wounds. In this study, electrospun poly(ɛ-caprolactone)/cellulose acetate blend nanofibers incorporating KE (PCL/CA/KE) were prepared and their performance was evaluated for healing acceleration of burn wounds. The physicochemical characterization of PCL/CA/KE nanofibers showed an average diameter of ∼420 nm, porosity of 70%, water contact angle of 61°, and water uptake of ∼220%. Moreover, the continuous release trend of KE from PCL/CA blend nanofibers happened during 24 h and the release mechanism was governed by the Fickian diffusion. Besides the cytocompatibility of PCL/CA/KE nanofibers, their in vivo experiments revealed that the bioactive wound dressing based on the sample has higher wound closure compared to KE after 21 days. Histopathology of wounds dressed by PCL/CA/KE nanofibers indicated epidermal formation along with a fully extended layer. Eventually, the obtained results confirmed that the PCL/CA/KE nanofibrous sample was a promising wound dressing for burn wound healing.

Production of Plant Proteases and New Biotechnological Applications: An Updated Review

An updated review of emerging plant proteases with potential biotechnological application is presented. Plant proteases show comparable or even greater performance than animal or microbial proteases for by‐product valorization through hydrolysis for, for example, cheese whey, bird feathers, collagen, keratinous materials, gelatin, fish protein, and soy protein. Active biopeptides can be obtained as high added value products, which have shown numerous beneficial effects on human health. Plant proteases can also be used for wastewater treatment. The production of new plant proteases is encouraged for the following advantages: low cost of isolation using simple procedures, remarkable stability over a wide range of operating conditions (temperature, pH, salinity, and organic solvents), substantial affinity to a broad variety of substrates, and possibility of immobilization. Vegetable proteases have enormous application potential for the valorization of industrial waste and its conversion into products with high added value through low‐cost processes.

The effects of kiwifruit dressing on hypertrophic scars in a rabbit ear model

AIMS

Hypertrophic scars show abnormal responses during healing. These scars, associated with dysregulated growth and excessive collagen formation, can have both functional and cosmetic consequences for patients. The present study evaluated the effects of kiwifruit on hypertrophic scars in a rabbit ear model.

METHODS

This study included 13 New Zealand albino rabbits with full thickness wounds down to the cartilage (four wounds per ear; total: 104 scars). Sixteen days after initial wound formation, one ear of each rabbit was treated with daily kiwifruit dressing, while the other ear (control group) was dressed after normal saline irrigation for 10 days. Harvested skin samples were examined for histopathological, morphometric and immunohistochemical results.

RESULTS

In comparison with the control group, early kiwifruit dressing significantly reduced the scar elevation index, fibroblast count and dermal collagen organisation. The ratio of collagen type III to total collagen immunoreactivity, inflammation and dermal capillary count increased significantly in the treated group, compared to the untreated controls.

CONCLUSION

Based on the findings, early kiwifruit dressing improved the histological features of cutaneous wounds in rabbits. Therefore, this approach may be effective in clinical practice.

Effect of Disulfide Bond Incorporation on the Structure and Activity of Endostatin Peptide

The structure and function of a 27-a.a. fragment of the N-terminal sequence of human endostatin (ES-Zn) were compared to those of the mutant peptide (ES-SSZn) obtained by adding Cys-Pro-Ala to the endostatin N-terminus and substituting Asn16 for Cys ensuring formation of a disulfide bond. Structural comparison of ES-Zn and ES-SSZn by far-UV circular dichroism (CD), intrinsic fluorescence, and molecular dynamics simulation methods revealed significant structural perturbations in ES-SSZn, such as elimination of the β-sheet conformer, modification of the N-terminal loop structure, and reorganization of dynamic properties of the entire peptide backbone. ES-SSZn was approximately 2 and 3 times less efficient than ES-Zn and the full-length human endostatin, respectively, in the induction of caspase-3-dependent apoptosis in human umbilical vein endothelial cells (HUVECs) in vitro (p < 0.05). In contrast, treatment of metastatic 4T1 breast tumors in mice with ES-Zn and ES-SSZn (5 mg/kg body weight daily) for 14 days resulted in similar regression of tumor size, comparable downregulation of angiogenesis (CD31 and CD34) and cell proliferation (Ki67), and therefore, the same extent of apoptosis induction (TUNEL, p53, and Bcl-2) for both peptides (as compared to the untreated controls). Western blot analysis of HUVEC and 4T1 tumor lysates revealed the same levels of suppression of key signaling mediators Akt and ERK1/2 by ES-Zn and ES-SSZn. Contrary to the earlier studies, our results showed that the function of the 1-27 endostatin fragment is independent of its overall structure. Stabilization of the N-terminal loop structure by the disulfide bond incorporation causes relief from structural deviations.

Engineering of a disulfide loop instead of a Zn binding loop restores the anti-proliferative, anti-angiogenic and anti-tumor activities of the N-terminal fragment of endostatin: Mechanistic and therapeutic insights

Although considerable effort has been devoted to understanding the molecular mechanism of endostatin's anti-cancer activity, the role of its Zn bound N-terminal loop has not been completely clarified. To investigate whether Zn binding or the N-terminal loop is involved in the anti-cancer properties of endostatin, we compared the structure and biological activity of a native Zn binding endostatin peptide (ES-Zn) with three variants: a Zn free variant (ES), a variant containing both a Zn binding site and a disulfide bond (ES-SSZn), and a variant including a disulfide loop but incapable of Zn binding (ES-SS). Spectroscopic studies indicated that ES-Zn and ES-SS consist of random coil and β structures, whereas ES-SSZn and ES fold into random coils. Theoretical analysis proposed that ES-Zn and ES-SS have a similar binding site to αVβ3 integrin. The anti-proliferative activity of endostatin was retained by all peptides except ES, and the in vitro anti-angiogenic property was preserved in ES-Zn and ES-SS. Remarkably, breast tumor growth and CD31 activity were inhibited more effectively by ES-SS than by ES-Zn. Therefore, a correlation exists between the N-terminal loop and anti-cancer properties of endostatin fragment and a disulfide loop may be more promising than a Zn binding loop for inhibiting tumor growth.

In vitro inhibition of angiogenesis by heat and low pH stable hydroalcoholic extract of Peganum harmala seeds via inhibition of cell proliferation and suppression of VEGF secretion

CONTEXT

Progression of cancer cells is completely dependent on its angiogenesis. Inhibition of tumor angiogenesis has shed new light on cancer treatment. As a result, anti-angiogenesis therapy represents one of the most significant advances in clinical oncology. Peganum harmala L. (Zygophyllaceae) is a native plant from the eastern Iranian region, which is used as a traditional folk medicine. Although some biological properties of this plant are determined, its effect on angiogenesis is still unclear.

OBJECTIVE

We investigated the anti-angiogenic effects of heat and low pH stable hydroalcoholic extract of P. harmala seeds on endothelial cells (ECs) proliferation and VEGF secretion.

MATERIALS AND METHODS

Dried Peganum seeds were purchased from Kermanshah Traditional Bazar in 2011. Hydroalcoholic extract of dried seeds (0, 10, 20, 40, 60, 80, 100, 120, and 150 μg/ml) was used for in vitro evaluation of its cytotoxicity, anti-proliferative, and anti-angiogenic effects on ECs. In vitro effect of the extract on VEGF secretion was assayed using ELISA.

RESULTS

Treatment with hydroalcoholic extract at seven different concentrations resulted in significant decrease of ECs proliferation and angiogenesis with an ID50 of ∼ 85 μg/ml. VEGF secretion was (inhibited) decreased by the extracts at concentrations higher than 10 μg/ml.

DISCUSSION AND CONCLUSION

Herbal plant extracts still attract attention owing to their fewer side effects comparing to synthetic drug agents. Current study indicated that hydroalcoholic extract of P. harmala seeds contains a potent anti-angiogenic component, which exerts its inhibitory effect mainly through down-regulation of essential mediators such as VEGF.

New procedure for epidermal cell isolation using kiwi fruit actinidin, and improved culture of melanocytes in the presence of leukaemia inhibitory factor and forskolin

OBJECTIVES

Conventional isolation of epidermis from the dermis and disruption of epidermal sheets to liberate the cells, are performed using proteolytic enzymes such as thermolysin or collagenase. Selective population expansion of melanocytes is achieved by suppressing proliferation of keratinocytes and fibroblasts in epidermal cell suspensions, using phorbol esters and cholera toxin. Here, we introduce a new procedure for isolation of epidermal cells, using proteolytic activity of kiwi fruit actinidin, and also an improved growth medium for melanocytes in the presence of leukaemia inhibitory factor (LIF) and forskolin.

MATERIALS AND METHODS

Dermo-epidermal separation and epidermal sheet cell dispersion were performed using actinidin compared to conventional proteases including collagenase, thermolysin or trypsin. Thereafter, melanocyte culture was performed in two common media and one modified medium to discover optimization for these cells.

RESULTS

We found that dermo-epidermal separation and epidermal sheet cell dispersion using kiwi fruit actinidin were considerably better than previously used methods, both from the aspect of less fibroblast and keratinocyte contamination, and of more viable native cells. Also, melanocytes proliferated better in phorbol ester- and cholera toxin-free proliferation medium supplemented with LIF and forskolin.

CONCLUSION

Less contamination and higher numbers of viable cells were actinidin preferential for separation of epidermis and isolation of epidermal cells. Supplementation of LIF and forskolin to new medium increased proliferation potential of melanocytes in comparison to exogenous mitogens.

An efficient method for purification of nonspecific lipid transfer protein-1 from rice seeds using kiwifruit actinidin proteolysis and ion exchange chromatography

Plant nonspecific lipid transfer proteins are small basic proteins that transport phospholipids between membranes and are subdivided into two subfamilies, nsLTP(1) (9 kDa) and nsLTP(2) (7 kDa). LTPs have potential application in the defense reactions against pathogens and the drug delivery systems. Many efforts have been made for purification of different nsLTPs from various plants; however, most of them used successive purification procedures. We have developed a relatively simple and efficient method for the purification of rice nsLTP(1), based on the proteolytic activity of kiwifruit actinidin on the rice seed extract and one-step chromatographic procedure on a CM-Sepharose column. The purity of protein was determined by reversed-phase high-performance liquid chromatography (RP-HPLC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The isolated LTP(1) migrated as a homogenous polypeptide with molecular mass of 9 kDa that confirms the efficiency of actinidin on the digestion of major contaminations present in the rice seed extract without any harmful effect on the LTP(1). The advantages of using proteolytic activity of actinidin in purifying rice LTP(1) includes the reduced separation time allowing the purification of LTP(1) in one-step chromatographic procedure, low costing, high efficiency, and the relative simplicity of the method.

Actinidin, a protease from kiwifruit, induces changes in morphology and adhesion of T84 intestinal epithelial cells

Actinidin belongs to the papain-like family of cysteine proteases and is a major kiwifruit allergen. In this study, the effect of actinidin on cellular morphology and adhesion of T84 intestinal cells was investigated. Both rounding and detachment of T84 cells were observed upon actinidin treatment. The morphological changes and cell desquamation was protease-dependent, as well as time- and concentration-dependent. Changes of intercellular adhesion and adhesion of epithelial cells to collagen upon actinidin treatment could be responsible for the cell rounding and give rise to discontinuous breaches in the epithelial monolayer observed in this study. Actinidin's action on cell morphology, adhesion and monolayer integrity were not due to compromised viability of T84 epithelial cells, as confirmed by MTT assay and flow cytometric analysis of the cell cycle. Damage to the epithelial monolayer of the intestine induced by actinidin should be further evaluated as an important factor in the development of kiwifruit allergy and other intestinal disorders.

Single cell analysis of complex thymus stromal cell populations: rapid thymic epithelia preparation characterizes radiation injury

Thymic epithelial cells (TECs) and dendritic cells are essential for the maintenance of thymopoiesis. Because these stromal elements define the progenitor niche, provide critical survival signals and growth factors, and direct positive and negative selection, detailed study of these populations is necessary to understand important elements for thymic renewal after cytotoxic injury. Study of TEC is currently hindered by lengthy enzymatic separation techniques with decreased viability. We present a new rapid separation technique that yields consistent viable TEC numbers in a quarter of the prior preparation time. Using this new procedure, we identify changes in stroma populations following total body irradiation (TBI). By flow cytometry, we show that TBI significantly depletes UEA+ medullary TEC, while sparing Ly51+ CD45- cells. Further characterization of the Ly51+ subset reveals enrichment of fibroblasts (CD45- Ly51+ MHCII-), while cortical TECs (CD45- Ly51+ MHCII+) were markedly reduced. Dendritic cells (CD11lc+ CD45+) were also decreased following TBI. These data suggest that cytotoxic preparative regimens may impair thymic renewal by reducing critical populations of cortical and medullary TEC, and that such thymic damage can be assessed by this new rapid separation technique, thereby providing a means of assessing optimal conditioning pretransplantfor enhancing thymic-dependent immune reconstitution posttranspiant.