kD Peptide Research Articles

Synthesis of biologically active proteins as L6KD-SUMO fusions forming inclusion bodies in Escherichia coli.

A new platform has been developed to facilitate the production of biologically active proteins and peptides in Escherichia coli. The platform includes an N-terminal self-associating L6 KD peptide fused to the SUMO protein (small ubiquitin-like protein modifier) from the yeast Saccharomyces cerevisiae, which is known for its chaperone activity. The target proteins are fused at the C termini of the L6 KD-SUMO fusions, and the resulting three-component fusion proteins are synthesized and self-assembled in E. coli into so-called active inclusion bodies (AIBs). In vivo, the L6 KD-SUMO platform facilitates the correct folding of the target proteins and directs them into AIBs, greatly simplifying their purification. In vitro, the platform facilitates the effective separation of AIBs by centrifugation and subsequent target protein release using SUMO-specific protease. The properties of the AIBs were determined using five proteins with different sizes, folding efficiencies, quaternary structure, and disulfide modifications. Electron microscopy shows that AIBs are synthesized in the form of complex fibrillar structures resembling "loofah sponges" with unusually thick filaments. The obtained results indicate that the new platform has promising features and could be developed to facilitate the synthesis and purification of target proteins and protein complexes without the use of renaturation.

IL-7: Comprehensive review.

IL-7 is a member of the family of cytokines with four anti-parallel α helixes that bind Type I cytokine receptors. It is produced by stromal cells and is required for development and homeostatic survival of lymphoid cells. Interleukin 7 (IL7) human IL7: gene ID: 3574 on ch 8; murine Il7 gene ID: 16,196 on ch 3. Precursor contains a signal sequence, mature human IL-7 peptide 152aa, predicted 17.4kd peptide, glycosylated resulting in 25kd. Crystal structure: http://www.rcsb.org/structure/3DI2. REGULATION OF IL-7 PRODUCTION: Major producers are stromal cells in thymus, bone marrow and lymphoid organs but also reported in other tissues. Production is primarily constitutive but reported to be affected by IFNγ and other factors. IL-7 RECEPTORS: Two chains IL-7Rα (IL-7R) and γc (IL-2RG). Human IL-7R: gene ID 3575 on ch 5; human IL2RG: gene ID 3561 on ch X; mouse IL-7R: gene ID 16,197 on ch 15; murine Il2rg gene ID 16,186 on ch X. Member of γc family of receptors for cytokines IL-2, -4, -9, -15, and -21. Primarily expressed on lymphocytes but reports of other cell types. Expression in T-cells downregulated by IL-7. Low expression on Tregs, no expression on mature B-cells. Crystal structure: http://www.rcsb.org/structure/3DI2. IL-7 RECEPTOR SIGNAL TRANSDUCTION PATHWAYS: Major signals through JAK1, JAK3 to STAT5 and through non-canonical STAT3, STAT1, PI3K/AKT and MEK/ERK pathways. BIOLOGICAL ACTIVITY OF IL-7: Required for survival of immature thymocytes, naïve T-cells, memory T-cells, pro-B-cells and innate lymphocytes. Pharmacological treatment with IL-7 induces expansion of naïve and memory T-cells and pro-B-cells. ABNORMALITIES OF THE IL-7 PATHWAY IN DISEASE: Deficiencies in the IL-7 pathway in humans and mice result in severe combined immunodeficiency due to lymphopenia. Excessive signaling of the pathway in mice drives autoimmune diseases and in humans is associated with autoimmune syndromes including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, sarcoidosis, atopic dermatitis and asthma. Mutations in the IL-7 receptor pathway drive acute lymphoblastic leukemia. IL-7 has been evaluated in patients with cancer and shown to expand lymphocytes. It accelerated lymphocyte recovery after hematopoietic stem cell transfer, and increased lymphocyte counts in AIDS patients and sepsis patients. Monoclonal antibodies blocking the IL-7 receptor are being evaluated in autoimmune diseases. Cytotoxic monoclonals are being evaluated in acute lymphoblastic leukemia. Drugs blocking the signal transduction pathway are being tested in autoimmunity and acute lymphoblastic leukemia.

SUMOylation of the Kv4.2 Ternary Complex Increases Surface Expression and Current Amplitude by Reducing Internalization in HEK 293 Cells.

Kv4 α-subunits exist as ternary complexes (TC) with potassium channel interacting proteins (KChIP) and dipeptidyl peptidase-like proteins (DPLP); multiple ancillary proteins also interact with the α-subunits throughout the channel’s lifetime. Dynamic regulation of Kv4.2 protein interactions adapts the transient potassium current, IA, mediated by Kv4 α-subunits. Small ubiquitin-like modifier (SUMO) is an 11 kD peptide post-translationally added to lysine (K) residues to regulate protein–protein interactions. We previously demonstrated that when expressed in human embryonic kidney (HEK) cells, Kv4.2 can be SUMOylated at two K residues, K437 and K579. SUMOylation at K437 increased surface expression of electrically silent channels while SUMOylation at K579 reduced IA maximal conductance (Gmax) without altering surface expression. KChIP and DPLP subunits are known to modify the pattern of Kv4.2 post-translational decorations and/or their effects. In this study, co-expressing Kv4.2 with KChIP2a and DPP10c altered the effects of enhanced Kv4.2 SUMOylation. First, the effect of enhanced SUMOylation was the same for a TC containing either the wild-type Kv4.2 or the mutant K437R Kv4.2, suggesting that either the experimental manipulation no longer enhanced K437 SUMOylation or K437 SUMOylation no longer influenced Kv4.2 surface expression. Second, instead of decreasing IA Gmax, enhanced SUMOylation at K579 now produced a significant ∼37–70% increase in IA maximum conductance (Gmax) and a significant ∼30–50% increase in Kv4.2g surface expression that was accompanied by a 65% reduction in TC internalization. Blocking clathrin-mediated endocytosis (CME) in HEK cells expressing the Kv4.2 TC mimicked and occluded the effect of SUMO on IA Gmax; however, the amount of Kv4.2 associated with the major adaptor for constitutive CME, adaptor protein 2 (AP2), was not SUMO dependent. Thus, SUMOylation reduced Kv4.2 internalization by acting downstream of Kv4.2 recruitment into clathrin-coated pits. In sum, the two major findings of this study are: SUMOylation of Kv4.2 at K579 regulates TC internalization most likely by promoting channel recycling. Additionally, there is a reciprocity between Kv4.2 SUMOylation and the Kv4.2 interactome such that SUMOylation regulates the interactome and the interactome influences the pattern and effect of SUMOylation.

Mechanisms of transplant rejection after the establishment of donor-specific tolerance

Abstract Patients weaned from immunosuppressive drugs can reject their graft after years of stability, often after an infection. We have modeled this in mice: infection with Listeria monocytogenes (Lm) at the maintenance phase of tolerance can precipitate rejection of a cardiac allograft. Here, we investigated which alloreactive Tconvs may mediate rejection after Lm infection. To track the function of allospecific Tconvs, we seeded tracer TCR75 cells, which recognize I-Ab-restricted donor Kd peptide, into B6 mice prior to Balb/c cardiac transplantation with or without tolerance induction by anti-CD154 + Balb/c splenocytes. ≥35 days post-transplantation, TCR75 cells persisting in tolerant mice developed a PD-1hi CD127lo exhausted-like phenotype and expressed the anergy markers FR4 and CD73. TCR75 cells were dysfunctional, exhibiting 10-fold less recall expansion compared to memory cells and lacked IFNγ and TNF production upon re-stimulation. Intriguingly, TCR75 cells in tolerant hosts remained dysfunctional after Lm infection, suggesting that they may not participate in infection-triggered rejection. Having found that programming T cell dysfunction in tolerance required persistence of the allograft for ~3 weeks, we tested whether T cells specific for alloantigens expressed transiently after transplantation, such as donor MHC Class II, remain functional during tolerance and may mediate rejection after Lm infection. We used tracer TEa cells specific for a donor Class II Eα peptide presented on I-Ab. During tolerance, TEa cells remained PD-1lo and CD73lo, and retained recall expansion and TNF production. We conclude that functional allospecific Tconvs present during tolerance may pose a previously unappreciated risk to the graft.

Isolation of Antimicrobials from Native Plants of Taif Governorate

Plant defensins are subgroup of plant antimicrobial peptides that have high potentials in developing safe natural agricultural and pharmaceutical biocontrol products as alternatives for the current chemical pesticides, insecticides, and antibiotics. In this study, the level of defensin gene expression was evaluated in floral buds of 9 native plants from Saudi Arabia environment using reverse transcription and polymerase chain reaction (RT-PCR). As defensins are highly expressed at the mRNA level in Ochradenus baccatus (Ob), it was used for the isolation of defensin peptides using ion exchange chromatography followed by gel filtration using Sephadex G50. SDS-PAGE of ion exchange purified proteins detected several bands in a range of 2–10 kD. These proteins were separated by gel filtration using Sephadex G50. The resultant peptide of 5 kD showed an antimicrobial activity. The peptide inhibited Gram positive and Gram negative bacteria with IC50 ranged from 10 to 25 μg/mL. It also inhibited 25 to 60% of fungal linear growth at concentrations of 12.5 and 25 μg/mL. The present results demonstrate that, we could separate and purify a 5 kD peptide from Ob. This peptide could be utilized to develop natural antimicrobial products.

Alloimmunogenicity of an isolated MHC allele is affected by the context of MHC mismatch in a murine model.

Humoral alloimmunization to human leukocyte antigen (HLA) can represent a barrier to solid-organ transplantation, can lead to a refractory state in patients requiring platelet transfusion, and can also contribute to transfusion-related acute lung injury (TRALI). While exposure to HLA-mismatched cells/tissues are generally required for HLA alloimmunization, the effect of the extent of major histocompatibility complex (MHC) mismatch between donor and recipient is poorly understood. A novel mouse was generated that allows the expression of a single MHC Class I alloantigen, Kd . Alloimmune responses to Kd were studied in C57BL/6 mice transfused with splenocytes from different donor mice, allowing the analysis of responses to Kd as an isolated alloantigen, or in the context of additional mismatched MHC molecules. Advanced tools were utilized to study responses to Kd , including T-cell receptor transgenic mice that recognize the immunodominant Kd peptide presented by C57BL/6 mice to CD4+ T cells. A single MHC Class I alloantigen mismatch is less immunogenic than when the same alloantigen is encountered in the context of additional mismatched MHC alloantigens. This difference is due, at least in part, to induction of CD4+ helper T cells, as the effect is overcome by increasing either mature CD4+ T-cell help through immunization or by increasing the precursor frequency of naïve CD4+ T cells by adoptive transfer from T-cell receptor transgenic donors. These findings indicate that the immunogenicity of a single alloantigen can be affected by the context in which it is encountered, demonstrating the potential for cooperative effects between different mismatched MHC alloantigens.

Identification of

Skins of anurans (frogs and toads) are rich sources of bioactive peptides. However, the peptides secreted by the skin glands of Bufo gargarizans, the most common toad in China, remained unexplored to date. Here, a strategy combines LC–MS/MS, RNA sequencing and bioinformation analysis was applied to unravel the peptides in the Bufo gargarizans secretions. Data-dependent LC–MS/MS acquisitions of intact peptides followed by automated chromatographic alignment, De novo analysis, database and homology searches with manual validations showed that the venom is composed by 939 features, with masses ranging from 0.7–4 kDa. These peptides derived from 85 proteins were identified using the PEAKS software with acquired MS and MS/MS spectra of Venenum Bufonis against the house-built protein database using De novo RNA sequencing, while only 23 peptides from 8 proteins were found when searching known amphibian database. Moreover, it was found that many peptides with high abundance in Venenum Bufonis derived from proteolytic processing of a larger precursor protein, named as CL4590. Molecular cloning was applied to validate a short domain of CL4590 to evident the accuracy of these obtained sequences. Although the bioactivities of peptides identified by MS/MS are unknown, the next function annotation showed that they may involve in the cell killing, immune and metabolic process, antioxidant activity and antimicrobial actions. Therefore, the peptidomics analysis on Bufo gargarizans discover abundant novel toad peptides which broaden our horizons on the secretion multiplicity and supplied an assortment of pharmacological candidates.

Different Damage to the Mechanical Barrier Function of IPEC-J2 Induced by Soybean Allergen β-conglycinin Hydrolyzed Peptides

Abstract Three major enzyme-hydrolyzed peptides have been produced after simulative digestion in vitro of soybean β-conglycinin. The intestinal barrier of IPEC-J2 induced by β-conglycinin enzyme-hydrolyzed peptides was evaluated in this study. The increased alkaline phosphatase (AP) activity was actually linearly correlated with the incubation time by the hydrolysate, the purified 52 kD peptide, or the mixture of 25 and 30 kD peptides. The MTT and TEER values declined in dose-dependence (0–2 mg/mL, p \lt 0.05) or in time-dependence (2–24 h, p \lt 0.05). After treatment with different hydrolyzed peptides, the tight junction expression of claudin-3, claudin-4, occludin, and ZO-1 were reduced (p \lt 0.05). Finally, it is found out that the maximum damage to the epithelial barrier function was induced by the mixture of 25 and 30 kD peptide, whereas the minimum damage was caused by the 52 kD peptide.

Recognition of Intact Donor Class I by Recipient CD8+ T Cells is Required for Tolerance Induction Following Liver-Directed Transgene Expression

Introduction: AAV-mediated expression of donor MHC I (H-2Kb or H-2Kd) in recipient liver induces donor-specific tolerance in a mouse skin transplant model where Kb or Kd are mismatched between donor and host [1]. Recognition of both intact and processed allogeneic class I could contribute to tolerance induction. Aims and Methods: To determine the relative importance of intact and processed class I in tolerance induction, we generated rAAV-Kb-D227K and Kd-D227K vectors where a point mutation in the class I alpha 3 domain abrogates CD8 binding [2] and direct allorecognition but does not interfere with recognition of processed peptides. Expression of WT or mutant class I on hepatocytes was assessed by FACS and IHC. TCR-transgenic T cells recognizing intact (Des-RAG) or processed (TCR75) allogeneic class I were used as reporter cells in adoptive transfer experiments. Skin bearing the mismatched MHC I was grafted onto uninjected recipients or mice inoculated with rAAV encoding WT or D227K mutant Kb or Kd. In some recipients, Tregs were depleted using anti-FR4 or Diphtheria toxin (DT). Interferon gamma production by responding T cells was determined using ELISpot. Results: WT and D227K class I were expressed on hepatocytes at comparable levels. Adoptive transfer assays confirmed that the D227K mutation abrogated recognition of intact Kb by CD8+ Des-RAG T cells, whilst recognition of processed Kd peptides by TCR75-RAG cells was unimpaired. Uninjected B10.BR mice rejected Kb-mismatched 178.3 skin (MST = 16 d), while grafts onto rAAV-Kb-injected mice survived indefinitely (p < 0.001). rAAV-Kb-D227K only slightly prolonged graft survival (MST = 27d, p < 0.05). These results were recapitulated in the B6.Kd to C57BL/6 model. The modest survival prolongation of skin grafts in mice inoculated with Kb-D227K was abrogated when the recipients were treated with anti-FR4 (clone TH6) to deplete Tregs. Similarly, the survival prolongation of Kd-mismatched B6.Kd grafts onto DEREG recipients treated with rAAV-Kd-D227K (MST = 28d compared with 20d in mice receiving DT alone) was blocked when mice receiving Kd-D227K were also treated with DT (MST 18 days, p = 0.0046). Treg depletion did not shorten survival of skin grafts in mice inoculated with WT MHC class I vectors. Interferon-gamma production by unfractionated or CD8-enriched splenocytes from primed C57BL/6 mice in response to B6.Kd stimulators was over fourfold lower in mice inoculated with WT Kd than in those receiving Kd-D227K (p = 0.038). Conclusions: Recognition of intact MHC class I by alloreactive CD8+ T cells is required for tolerance induction via liver-directed expression of donor MHC class I. Indirect recognition of class I allopeptides and generation of Tregs can produce a modest prolongation of class I-mismatched skin graft survival but does not induce tolerance.FigureFigure

Tracking of TCR-Transgenic T Cells Reveals That Multiple Mechanisms Maintain Cardiac Transplant Tolerance in Mice.

Solid organ transplantation tolerance can be achieved following select transient immunosuppressive regimens that result in long-lasting restraint of alloimmunity without affecting responses to other antigens. Transplantation tolerance has been observed in animal models following costimulation or coreceptor blockade therapies, and in a subset of patients through induction protocols that include donor bone marrow transplantation, or following withdrawal of immunosuppression. Previous data from our lab and others have shown that proinflammatory interventions that successfully prevent the induction of transplantation tolerance in mice often fail to break tolerance once it has been stably established. This suggests that established tolerance acquires resilience to proinflammatory insults, and prompted us to investigate the mechanisms that maintain a stable state of robust tolerance. Our results demonstrate that only a triple intervention of depleting CD25+ regulatory T cells (Tregs), blocking programmed death ligand-1 (PD-L1) signals, and transferring low numbers of alloreactive T cells was sufficient to break established tolerance. We infer from these observations that Tregs and PD-1/PD-L1 signals cooperate to preserve a low alloreactive T cell frequency to maintain tolerance. Thus, therapeutic protocols designed to induce multiple parallel mechanisms of peripheral tolerance may be necessary to achieve robust transplantation tolerance capable of maintaining one allograft for life in the clinic.

Extended Duration of Transgene Expression from Pegylated POD Nanoparticles Enables Attenuation of Photoreceptor Degeneration

Retinitis pigmentosa (RP) is the most genetically heterogeneous disorder known to cause blindness, involving over 50 different genes. Previously, we have described nanoparticles (NPs) 150 nm in size, comprised of a 3.5 kD peptide (POD) complexed to PEG and DNA (PEGPOD DNA). These NPs expressing GDNF enabled rescue of photoreceptor degeneration in mice up to 11 days post injection. In the current study we examine use of scaffold/ matrix attachment regions (S/MARs), CpG depletion and titration of DNA content of PEGPOD DNA NPs to extend the duration of transgene expression. S/MARs and CpGs did not significantly influence the duration of transgene expression, but did influence its stability. These parameters enabled us to extend transgene expression from 48 hours to 10 weeks. At 77 days post injection, we observed a 76% rescue of the thickness of the retinal outer nuclear layer (ONL) and at 37 days post injection we observed 53% and 55% rescue of the A and B wave ERG amplitudes respectively and 60% rescue of the ONL. Our studies suggest that PEGPOD DNA NPs have potential as gene delivery vectors for the retina.

Abstract 464: Tumor derived vacuolar ATPase subunit promotes M2 type polarization of macrophages.

Abstract Tumors and tumor associated macrophages (TAMs) express a unique surface vacuolar ATPase (V-ATPase) on the plasma membrane. In tumor cells, a 20 kd peptide is cleaved from a2 isoform of V-ATPase and is referred to as a2NTD; it is associated with in vitro induction of pro-tumorigenic properties in monocytes and IL-β secretion. In this study, we evaluated the immuno-modulatory properties of a2NTD in inducing murine peritoneal macrophage polarization and activation of inflammasome components both ex vivo and in vivo. Peritoneal macrophages from BALB/c mice were stimulated with recombinant a2NTD and the mRNA and protein expression of M1 (CD11c, TNF-α), M2 (Mannose receptor-1, Arginase-1, IL-10) markers, IL-1β and NLRP3 (inflammasome marker) were analyzed using quantitative real time PCR and flow cytometry. Further, mice were injected with a2NTD i.p. and peritoneal cells were analyzed for M1/M2 specific markers. The results of both in vivo and ex vivo analysis showed an elevated population of M2 subtype in a2NTD-treated mice compared to control (P&amp;lt;0.05). a2NTD upregulated the expression of IL-1β and NLRP3 in macrophages. These data demonstrated that a2NTD modulates macrophage polarization towards the M2 subtype functionally similar to tumor associated macrophages (TAMs). Since, tumor progression requires sterile inflammation and maturation of resident macrophages into TAMs; our data provide evidence that the surface expression of V-ATPase in tumor cells has a role in inducing the unique inflammatory environment of tumors by modulating macrophage phenotype and inducing IL-1β production through the action of a2NTD. The study also provides indication for the involvement of a2NTD in NLRP3 mediated inflammasome activation. Citation Format: Gajendra K. Katara, Mukesh K. Jaiswal, Alice Gilmam-Sacks, Kenneth D. Beaman. Tumor derived vacuolar ATPase subunit promotes M2 type polarization of macrophages. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 464. doi:10.1158/1538-7445.AM2013-464

Abstract 5282: Pretargeted immunoPET for imaging human colonic cancer in a mouse model

Abstract Objective: Molecular imaging with pretargeting bispecific antibodies allows rapid and specific targeting of tumors for PET imaging. In this study, pretargeted immunoPET with a bispecific monoclonal anti-carcinoembryonic antigen (CEA; CEACAM5) × anti-hapten antibody (bsMAb) and a small (1.5 kD) peptide labeled with a short-lived positron-emitter 68Ga was compared to FDG for detection of intraperitoneal CEA-expressing human colonic tumor xenografts in nude mice. Methods: In BALB/c nude mice LS174T human colonic tumor cells were injected intraperitoneally. One group (n=5) received 5 MBq FDG i.v., and another group (n=5) received the bsMAb i.v. and 5 MBq of 68Ga-labeled peptide i.v. 16 h later. One hour after the injection of the peptide or FDG, PET/CT images were acquired. One day later the same procedure was repeated vice versa, and after microPET imaging the uptake of the 68Ga or 18F in dissected tissue was determined. Results: Within one hour, specific tumor targeting of 68Ga-labeled peptide (23.4 ± 7.2% ID/g) combined with the low background activity levels resulted in the clear visualization of the small intra-abdominal tumor lesions (1.5-5 mm). High tumor/background radioactivity concentration ratios were obtained (e.g. tumor/intestines 57.5 ± 22.4). FDG localized efficiently in the tumors (8.7 ± 3.1 % ID/g), but with physiological uptake in various normal tissues (ratio tumor/intestines 4.0 ± 0.9). Conclusion: Pretargeted immunoPET performs exceptionally well with short-lived radionuclides, and is a highly sensitive procedure for dectection of small tumor deposits that is also more specific than FDG-PET. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5282. doi:10.1158/1538-7445.AM2011-5282

Response of Crypt Paneth Cells in the Small Intestine following Total-Body γ-Irradiation

Ionizing irradiation causes damage and functional failure of irradiation-sensitive systems and tissues such as small intestine. The molecular mechanisms underlying inflammatory and adaptive responses to acute irradiation damage are poorly understood. Using a mouse model of total-body γ-irradiation, we assessed the irradiation response of crypt host-defense Paneth cells by measuring alpha-defensin 4 (AD4) expression and correlated the gathered data with activation of the caspase-1/IL-1β inflammatory signaling cascade. The irradiation injury was produced in CD2F1 mice exposed to 9.25 Gy γ-radiation. This dose resulted in 85-100 percent mortality at the 15(th) day post-irradiation. Small intestine tissue samples were collected at the 7th day post-irradiation. Assessment of irradiation-associated pro-inflammatory alterations in small intestine tissue and expression of AD4 in Paneth cells was conducted using confocal immunofluorescence imaging, transmission electron microscopy (TEM), light microscopy, and immunoblotting techniques. The small intestine analysis revealed an increase in the precursor form of IL-1β, the activated form of IL-1β, and the activated form of caspase-1 (p10 CASP-1) at the 7(th) day post-irradiation. Immunoprecipitation analysis showed increased interaction between IL-1β and p10 CASP-1 after irradiation. This effect was observed in the irradiated small intestine and CD15-positive Paneth cells using confocal imaging techniques. The pro-inflammatory alterations in Paneth cells were accompanied by increases in AD4 mRNA and its 8 kD peptide product. Paneth cell secretory activity was observed at the sites of bacterial translocation in the crypt lumens. These data suggest that Paneth cells can contribute to small intestine inflammatory remodeling during the post-irradiation period.

Inflammatory mediators in the aqueous humor from patients with uveitis associated with Behçet’s disease and Vogt‐Koyanagi‐Harada disease

Abstract Purpose We studied interphotoreceptor retinoid‐binding protein (IRBP), a dominant autoimmune antigen in the eye. Methods Aqueous humour samples from 28 patients with active uveitis were analysed for immunoglobulin G (IgG) content as a marker for blood‐ocular barrier breakdown and by gelatinase B zymography for the detection of inflammation. The data were correlated with the presence of intact IRBP (approximately 140 kD) as determined by Western blot analysis and with the clinical disease activity. Results Aqueous humour samples from control eyes and eyes with low disease activity showed positive immunoreactivity for intact IRBP. The IRBP signal weakened or disappeared with higher disease activity. Significant positive correlations were observed between disease activity and levels of gelatinase B/matrix metalloproteinase‐9 (MMP‐9) (rs=0.713; P&lt;0.001) and IgG (rs=0.580; P=0.001). Significant negative correlations were found between levels of IRBP and disease activity (rs=‐0.520; P=0.005) and levels of MMP‐9 (rs=‐0.727; P&lt;0.001) and of IgG (rs=‐0.834; P&lt;0.001). Whereas neutrophil elastase converted intact IRBP into an immunoreactive 55 kD peptide in vitro, the conversion by neutrophil degranulates resembled more the in vivo context with a complete degradation of IRBP. Reversal of inflammation with immunosuppressive therapy was accompanied with reappearance of intact IRBP and disappearance of IgG and MMP‐9. Conclusion The analysis of IRBP proteolysis is useful as a biomarker for uveitis and suggests that inhibition of proteinases might become a therapeutic strategy in an inflammatory context of a damaged blood‐ocular barrier.

A unique proteolytic fragment of alpha1-antitrypsin is elevated in ductal fluid of breast cancer patient

By comparison of mass spectra from a small cohort of nipple aspiration fluids (NAF), we previously discovered a panel of five candidate breast cancer biomarkers among them an unidentified 4.7 kD peptide BF5. The purposes of the present study were to verify the presence of BF5 in an independent cohort; to determine the protein identity of BF5; and to provide insight into the biology of BF5 production and elevation in tumor-associated NAF. We prospectively collected bilaterally matched NAF from patients with unilateral Stage I/II breast cancer (IBC-31), ductal carcinoma in situ (DCIS-6), atypical ductal hyperplasia (ADH-5), and presumed healthy women who came to routine mammography and had a normal exam (31). Following the consolidation of its cancer-associated expression on SELDI-mass spectrometry, BF5 was isolated by gel electrophoresis and sequenced by tandem mass spectrometry. BF5 was elevated in 15-25% of women with IBC, DCIS, or ADH vs. 0% of controls. This elevation was restricted to the affected breasts. BF5 was identified as 41/42-aa C-terminal peptide of alpha1-antitrypsin (AAT), the principle inhibitor of serine protease neutrophile elastase. The full length AAT showed a consistent expression pattern as C-41/42, and C-41/42 can be generated in vitro by MMP-7 cleavage. In conclusion, elevated C-41/42 is likely the result of elevated AAT synthesis, and the activity of specific MMPs present within the tumor. As other C-terminal fragments of AAT are reported to function as tumor-derived suppressors to the host immune-system, elevated C-41/42 may also be predictive of a poor outcome.

Achyranthoside H methyl ester, a novel oleanolic acid saponin derivative from Achyranthes fauriei roots, induces apoptosis in human breast cancer MCF-7 and MDA-MB-453 cells via a caspase activation pathway

Achyranthoside H methyl ester (AH-Me) is an oleanolic acid saponin derivative isolated from the roots of Achyranthes fauriei through diazomethane treatment. AH-Me exhibited significant cytotoxicity against human breast cancer MCF-7 and MDA-MB-453 cells, with respective ID(50) values of 4.0 and 6.5 muM: in the MTT assay. AH-Me is a unique saponin containing three methoxycarbonyl groups in the sugar moiety linked to the C-3 position of oleanolic acid. The demethylation of these methoxycarbonyl groups by alkaline hydrolysis caused a marked reduction of the cytotoxicity of AH-Me, suggesting that the methoxycarbonyl groups of AH-Me are key groups for the acquisition of cytotoxicity against human cancer cells. The staining of cancer cells with 4',6'-diamidino-2-phenylindole (DAPI) showed that the population of cells with altered nuclear morphology, for example chromatin condensation and fragmentation, increased markedly after AH-Me treatment. Exposure of MCF-7 and MDA-MB-453 cells to AH-Me resulted in a dose-dependent and time-dependent increase in the sub-G1 population, and in the cleavage of poly-ADP-ribose polymerase (PARP) followed by the formation of an 89 kD peptide. Pretreatment of the cells with the pan-caspase inhibitor z-VAD-fmk abolished the cleavage of PARP by AH-Me treatment and suppressed the antiproliferative effect of AH-Me on tumor cell growth. These results together led to the suggestion that AH-Me induces apoptosis via the caspase activation pathway in human breast cancer cells, and apoptosis is the major mode of the cytotoxic effect triggered by AH-Me.

Emulsification alters simulated gastrointestinal proteolysis of β-casein and β-lactoglobulin

We have studied the effect of the adsorption of milk proteins at the oil-water interface on their digestibility in simulated gastrointestinal environment. The investigations aimed to characterize how both the breakdown of the adsorbed proteins and the interactions with physiological surfactants, phosphatidylcholine (PC) and bile salts (BS), influence structural transformations of model, protein-stabilized food emulsions in the gastrointestinal track. Proteolysis of two contrasting proteins, β-casein (β-Cas) and β-lactoglobulin (β-Lg), was compared between the protein presented in solution or in emulsion, after adsorption at the oil-water interface. Digestion of β-Cas was faster when presented as an emulsion and led to the persistence of a 6 kD peptide not seen when the protein was presented in solution. Adsorption gave rise to a pepsin-susceptible form of β-Lg. Complex interactions were observed with PC introduced to the system in the vesicular form. Measurements of interfacial tension revealed that PC displaced the proteins from the oil droplets after only 30 s for β-Lg and 12 min for β-Cas, so that the gastric digestion largely took place in solution. Pepsinolysis of adsorbed β-Cas played a dominant role in emulsion destabilization. In contrast, collapse of β-Lg-stabilized emulsion under gastric conditions was mainly dependent on protein-PC interactions. β-Lg was significantly protected through simulated duodenal digestion as a result of a complex formed with the PC. In the absence of PC, the proteins were completely broken down after duodenal digestion, during which the duodenal surfactants, BS, displaced any remaining protein from the interface and governed the final structure of emulsion.

Interphotoreceptor retinoid‐binding protein as biomarker in systemic autoimmunity with eye inflictions

Autoimmune diseases of the eye, exemplified by Beh cet disease and Vogt-Koyanagi-Harada disease, are a major cause of blindness. We studied interphotoreceptor retinoid-binding protein (IRBP), a dominant autoimmune antigen in the eye. Aqueous humour samples from 28 patients with active uveitis were analysed for immunoglobulin G (IgG) content as a marker for blood-ocular barrier breakdown and by gelatinase B zymography for the detection of inflammation. The data were correlated with the presence of intact IRBP (≈140 kD) as determined by Western blot analysis and with the clinical disease activity. Aqueous humour samples from control eyes and eyes with low disease activity showed positive immunoreactivity for intact IRBP. The IRBP signal weakened or disappeared with higher disease activity. Significant positive correlations were observed between disease activity and levels of gelatinase B/matrix metalloproteinase-9 (MMP-9) (rs= 0.713; P < 0.001) and IgG (rs= 0.580; P= 0.001). Significant negative correlations were found between levels of IRBP and disease activity (rs=−0.520; P= 0.005) and levels of MMP-9 (rs=−0.727; P < 0.001) and of IgG (rs=−0.834; P < 0.001). Whereas neutrophil elastase converted intact IRBP into an immunoreactive 55 kD peptide in vitro, the conversion by neutrophil degranulates resembled more the in vivo context with a complete degradation of IRBP. Reversal of inflammation with immunosuppressive therapy was accompanied with reappearance of intact IRBP and disappearance of IgG and MMP-9. The analysis of IRBP proteolysis is useful as a biomarker for uveitis and suggests that inhibition of proteinases might become a therapeutic strategy in an inflammatory context of a damaged blood-ocular barrier.

Antigen, in the Presence of TGF-β, Induces Up-Regulation ofFoxP3gfp+ in CD4+ TCR Transgenic T Cells That Mediate Linked Suppression of CD8+ T Cell Responses

CD4(+)CD25(+) regulatory T cells (Tregs) inhibit immune responses to a variety of Ags, but their specificity and mechanism of suppression are controversial. This controversy is largely because many studies focused on natural Tregs with undefined specificities and suppression has frequently been measured on polyclonal T cell responses. To address the issue of specificity further, we have bred K(d)-specific, CD4(+) TCR (TCR75) transgenic mice to Foxp3(gfp) knockin reporter mice to permit sorting of Tregs with a known specificity. Foxp3(gfp).TCR75 mice did not express significant numbers of natural FoxP3(+) Tregs expressing the TCR75 transgenes, but FoxP3 expression was induced by stimulating with K(d) plus TGF-beta. The resulting GFP(+) TCR75 cells were anergic, whereas the GFP(-) TCR75 cells proliferated upon restimulation with K(d) peptide. Yet both exhibited severely reduced expression of intracellular IFN-gamma and TNF-alpha upon restimulation. GFP(+), but not GFP(-), TCR75 T cells suppressed responses by naive TCR75 T cells and by nontransgenic spleen cells stimulated with anti-CD3. GFP(+) TCR75 cells also inhibited polyclonal C57BL/6 anti-K(d) CTL responses if the APC expressed K(d) and both MHC class I and class II, and responses by OT1 T cells to B6.K(d).OVA but not B6.K(d) plus OVA expressing APC, demonstrating linked-suppression of CD8 responses. Thus, Tregs exhibit a greater degree of specificity in vitro than previously appreciated. The observation that Tregs and responder T cells must recognize the same APC provides a mechanistic explanation for the observation that Tregs must be in direct contact with effector T cells to suppress their responses.