2D Immunoblotting Research Articles

Recognition of tumor antigens in 4T1 cells by natural IgM from three strains of mice with different susceptibilities to spontaneous breast cancer.

The issue of antibody responses to tumors is potentially important to cancer immunologists. Early detection of cancer represents one of the most promising approaches to reduce the growing cancer burden. Natural immunoglobulin (Ig)M antibodies have been associated with the recognition and elimination of cancerous and precancerous cells. Using natural IgM antibodies, the present study identified a set of antigens in healthy mice from three different strains and examined whether the global patterns of antibodies are able to discriminate between a condition of more or less susceptibility to breast cancer. The current study performed two-dimensional (2D) immunoblotting to detect antigens from 4T1 cells using natural IgM from serum of healthy female mice from three different strains. The t-test was used to analyze the total number of spots. There were no significant differences in the numbers of antigens recognized in each strain. However, differences in patterns were observed on 2D immunoblots among the three strains. The reactivity patterns of natural IgM antibodies to particular antigens exhibited non-random clustering, which discriminated between strains with different susceptibilities to spontaneous breast cancer. The results demonstrated that the patterns of reactivity to defined subsets of antigens are able to provide information regarding differential diagnosis associated with breast cancer sensitivity. Therefore, it may be concluded that it is possible to segregate the IgM humoral immune response toward cancer antigens according to the genetic background of individuals. In addition, it is possible to identify the recognized antigens that allow grouping or discriminate between the different IgM antibodies expressed. The possible association between a particular antigen and cancer susceptibility requires further study, but the methodology exposed in the present study may identify potential candidates for this possible association.

Immunoproteomic analysis of house dust mite antigens reveals distinct classes of dominant T cell antigens according to function and serological reactivity.

House dust mite (HDM) allergens are a common cause of allergy and allergic asthma. A comprehensive analysis of proteins targeted by T cells, which are implicated in the development and regulation of allergic disease independent of their antibody reactivity, is still lacking. To comprehensively analyse the HDM-derived protein targets of T cell responses in HDM-allergic individuals, and investigate their correlation with IgE/IgG responses and protein function. Proteomic analysis (liquid chromatography-tandem mass spectrometry) of HDM extracts identified 90 distinct protein clusters, corresponding to 29 known allergens and 61 novel proteins. Peripheral blood mononuclear cells (PBMC) from 20 HDM-allergic individuals were stimulated with HDM extracts and assayed with a set of ~2500 peptides derived from these 90 protein clusters and predicted to bind the most common HLA class II types. 2D immunoblots were made in parallel to elucidate IgE and IgG reactivity, and putative function analyses were performed in silico according to Gene Ontology annotations. Analysis of T cell reactivity revealed a large number of T cell epitopes. Overall response magnitude and frequency was comparable for known and novel proteins, with 15 antigens (nine of which were novel) dominating the total T cell response. Most of the known allergens that were dominant at the T cell level were also IgE reactive, as expected, while few novel dominant T cell antigens were IgE reactive. Among known allergens, hydrolase activity and detectable IgE/IgG reactivity are strongly correlated, while no protein function correlates with immunogenicity of novel proteins. A total of 106 epitopes accounted for half of the total T cell response, underlining the heterogeneity of T cell responses to HDM allergens. Herein, we define the T cell targets for both known allergens and novel proteins, which may inform future diagnostics and immunotherapeutics for allergy to HDM.

Cyclophilin and enolase are the most prevalent conidial antigens of Lomentospora prolificans recognized by healthy human salivary IgA and cross‐react with Aspergillus fumigatus

The study of the immunocompetent airways immune response may provide important information to improve the therapeutic efficacy against Lomentospora (Scedosporium) prolificans. So, this study aimed to identify the most prevalent conidial antigens of this multiresistant fungus recognized by healthy human salivary immunoglobulin A, and to study their expression and cross-reactivity with other fungal species. Twenty saliva from immunocompetent donors were used to detect and identify the immunoreactive proteins by 2D immunoblotting and LC-MS/MS. Moreover, anti-Aspergillus antibodies were purified to study their cross-reactivity. Ten proteins of L. prolificans conidia showed reactivity with more than 50% of the saliva samples. Among them, cyclophilin and enolase were the most prevalent antigens recognized by 85 and 80% of the samples, respectively. These enzymes were also identified on the cell wall surface of L. prolificans and on the immunomes of Scedosporium apiospermum and Scedosporium aurantiacum. Additionally, they showed cross-reactivity with the most common pathogenic filamentous fungus Aspergillus fumigatus. These results show that the immunocompetent immune response might offer a pan-fungal recognition of conserved antigens such as enolase and cyclophilins, making them potential candidates for study as therapeutic targets.

Development of soybeans with low P34 allergen protein concentration for reduced allergenicity of soy foods.

In soybean, at least 16 seed proteins have been identified as causing allergenic reactions in sensitive individuals. As a soybean genebank accession low in the immunodominant protein P34 (Gly m Bd 30K) has recently been found, introgression of the low-P34 trait into adapted soybean germplasm has been attempted in order to improve the safety of food products containing soybean protein. Therefore, marker-assisted selection and proteomics were applied to identify and characterize low-P34 soybeans. In low-P34 lines selected from a cross-population, concentrations of the P34 protein as identified with a polyclonal antibody were reduced by 50-70% as compared to P34-containing controls. Using 2D electrophoresis and immunoblotting, the reduction of P34 protein was verified in low-P34 lines. This result was confirmed by liquid chromatographic-tandem mass spectrometric analysis, which revealed either a reduction or complete absence of the authentic P34 protein as suggested from presence or absence of a unique peptide useful for discriminating between conventional and low-P34 lines. Marker-assisted selection proved useful for identifying low-P34 soybean lines for the development of hypoallergenic soy foods. The status of the P34 protein in low-P34 lines needs further characterization. In addition, the food safety relevance of low-P34 soybeans should be tested in clinical studies. © 2016 Society of Chemical Industry.

Prospective investigation on the transfer of Ara h 2, the most potent peanut allergen, in human breast milk

Peanut allergy is one of the most severe food allergies. Whether breastfeeding induces tolerance to peanuts or on the contrary, pre-disposes at risk-babies to occult allergic sensitization to peanuts is still a matter of discussion. We sought to investigate the transfer of the most potent peanut allergen Ara h 2 into human breast milk in a German breast milk study and to shed light on the time kinetics of Ara h 2 appearance. We recruited 32 lactating, non-peanut-allergic women and collected breast milk samples at different time points after consumption of 100g dry roasted peanuts. Breast milk samples were investigated for Ara h 2 with different immunological methods: by 2D immunoblotting with a patient's serum, by affinity enrichment using a monoclonal antibody against Ara h 2 followed by LC-MS/MS-based detection and by a competitive inhibition ELISA for the detection of Ara h 2 and its digestion-resistant peptides (DRP-Ara h 2). In a qualitative analysis, Ara h 2 could be identified in a breast milk sample by 2D immunoblot by means of a patient's serum and furthermore by immunoaffinity enrichment followed by LC-MS/MS analysis. In a semi-quantitative analysis, Ara h 2 and its digestion-resistant peptides were detected in the breast milk of 9 of 32 subjects. Evidence suggests that Ara h 2 is excreted individually either rapidly (after 1, 2, 3 or 4h) or delayed (after 8 or 12h) and in different concentrations. Time and concentration of secreted Ara h 2 in breast milk appears to be individually regulated. The identification of Ara h 2 in breast milk is the prerequisite for the investigation of its sensitizing or tolerogenic properties.

Proteomic analysis of protein carbonylation: a useful tool to unravel nanoparticle toxicity mechanisms.

BackgroundOxidative stress, a commonly used paradigm to explain nanoparticle (NP)-induced toxicity, results from an imbalance between reactive oxygen species (ROS) generation and detoxification. As one consequence, protein carbonyl levels may become enhanced. Thus, the qualitative and quantitative description of protein carbonylation may be used to characterize how biological systems respond to oxidative stress induced by NPs.MethodsWe investigated a representative panel of 24 NPs including functionalized amorphous silica (6), zirconium dioxide (4), silver (4), titanium dioxide (3), zinc oxide (2), multiwalled carbon nanotubes (3), barium sulfate and boehmite. Surface reactivities of all NPs were studied in a cell-free system by electron spin resonance (ESR). NRK-52E cells were treated with all NPs, analyzed for viability (WST-1 assay) and intracellular ROS production (DCFDA assay). Carbonylated proteins were assessed by 1D and/or 2D immunoblotting and identified by matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF/TOF). In parallel, tissue homogenates from rat lungs intratracheally instilled with silver NPs were studied.ResultsEleven NPs induced elevated levels of carbonylated proteins. This was in good agreement with the surface reactivity of the NPs as obtained by ESR and the reduction in cell viability as assessed by WST-1 assay. By contrast, results obtained by DCFDA assay were deviating. Each NP induced an individual pattern of protein carbonyls on 2D immunoblots. Affected proteins comprised cytoskeletal components, proteins being involved in stress response, or cytoplasmic enzymes of central metabolic pathways such as glycolysis and gluconeogenesis. Furthermore, induction of carbonyls upon silver NP treatment was also verified in rat lung tissue homogenates.ConclusionsAnalysis of protein carbonylation is a versatile and sensitive method to describe NP-induced oxidative stress and, therefore, can be used to identify NPs of concern. Furthermore, detailed information about compromised proteins may aid in classifying NPs according to their mode of action.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-015-0108-2) contains supplementary material, which is available to authorized users.

Enzymatic Hydrolysis Does Not Reduce the Biological Reactivity of Soybean Proteins for All Allergic Subjects.

Many soybean protein products are processed by enzymatic hydrolysis to attain desirable functional food properties or in some cases to reduce allergenicity. However, few studies have investigated the effects of enzymatic hydrolysis on the allergenicity of soybean products. In this study the allergenicity of soybean protein isolates (SPI) hydrolyzed by Alcalase, trypsin, chymotrypsin, bromelain, or papain was evaluated by IgE immunoblots using eight soybean-allergic patient sera. The biological relevance of IgE binding was evaluated by a functional assay using a humanized rat basophilic leukemia (hRBL) cell line and serum from one subject. Results indicated that hydrolysis of SPI by the enzymes did not reduce the allergenicity, and hydrolysis by chymotrypsin or bromelain has the potential to increase the allergenicity of SPI. Two-dimensional (2D) immunoblot and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of the chymotrypsin-hydrolyzed samples indicated fragments of β-conglycinin protein are responsible for the apparent higher allergenic potential of digested SPI.

Comparison patterns of 4 T1 antigens recognized by humoral immune response mediated by IgG and IgM antibodies in female and male mice with breast cancer using 2D-immnunoblots

The early detection of cancer is one of the most promising approaches to reduce its growing burden and develop a curative treatment before the tumor is established. The early diagnosis of breast cancer is the most demanding of all tumors, because it is the most common cancer in women worldwide. We have described a new approach to analyze humoral immune reactions against 4 T1 cell antigens in female mice, reporting that the IgG and IgM responses differed and varied over time and between individuals. In this study, we compared and analyzed the detection of tumor antigens with IgG and IgM from the sera of male mice that were injected with 4 T1 cells into the mammary gland nipple in 2D immunoblot images. The variability in IgM and IgG responses in female and male mice with breast cancer at various stages of disease was characterized, and the properties with regard to antigen recognition were correlated statistically with variables that were associated with the individuals and tumors.The ensuing IgG and IgM responses differed. Only the IgG response decreased over time in female mice – not in male mice. The IgM response was maintained during tumor development in both sexes. Each mouse had a specific pattern of antigen recognition – ie, an immunological signature – represented by a unique set of antigen spots that were recognized by IgM or IgG. These data would support that rationale IgM is a better tool for early diagnosis, because it is not subject to immunosuppression like IgG in female mice with breast cancer.

What is the impact of genetic transformation on wheat allergenicity?

Wheat allergy occurs by inhalation (baker's asthma) and ingestion (food allergy), but may also develop by contact in some cases. The responsible allergens of wheat are proteins accounting for about 10-15% of the grain dry weight. Wheat proteins are divided into two groups: the salt soluble fraction (albumins/globulins) and the gluten proteins (gliadins and glutenins). This latter group is responsible for celiac disease and also for food allergy, whereas the albumins/globulins are involved in baker's asthma and in some food allergy. Genetic modification (GM) technology for crop improvement has recently emerged and its impact on allergenicity must be evaluated, as recommended by the Codex Alimentarius. Following this recommendation, we first compared two GM lines with their parents using an allergenomic approach then in a second step we aimed at comparing the amount of allergenic polypeptides in these GM wheats, their untransformed genotypes and those measured among twenty commercial cultivars, either durum or bread wheats. In order to characterize the accumulation of allergenic proteins in wheats, sera from children and adults with clinically documented wheat allergy were used. The investigation is focused mainly on the soluble protein fraction of wheat. For the comparison of GM lines with their natural counterparts, 2D immunoblot followed by mass spectrometry analysis and protein identification was set up. ELISA tests were performed on the whole set of genotypes. Few differences at molecular and quantitative levels were revealed between the GM lines and their counterparts. Two new IgE-binding proteins were detected for one GM line.[1] We also observed that the genetic transformation may impact IgE reactivity, either in a positive or in a negative way.[2] This study leads us to conclude that a wide variation exists in the amount of allergenic polypeptides among durum and bread wheat cultivars, and that the differences observed between GM wheats and their parents are within the range of these 20 cultivated wheats.

Glutamine enema regulates colonic ubiquitinated proteins but not proteasome activities during TNBS-induced colitis leading to increased mitochondrial activity.

Ubiquitin proteasome system contributes to the regulation of intestinal inflammatory response as its inhibition is associated with tissue damage improvement. We aimed to evaluate whether glutamine is able to limit inflammation by targeting ubiquitin proteasome system in experimental colitis. Colitis was induced in male rats by intrarectal instillation of 2-4-6-trinitrobenzen sulfonic acid (TNBS) at day 1. From day 2 to day 6, rats daily received either an intrarectal instillation of PBS (TNBS/PBS group) or glutamine (TNBS/Gln). Rats were euthanized at day 7 and colonic samples were taken to evaluate ubiqutinated proteins by proteomic approach combining 2D electrophoresis and immunoblots directed against ubiquitin. Results were then confirmed by evaluating total expression of proteins and mRNA levels. Survival rate, TNFα, and IL-1β mRNA were improved in TNBS/Gln compared with TNBS/PBS (p < 0.05). Proteasome activities were affected by TNBS but not by glutamine. We identified eight proteins that were less ubiquitinated in TNBS/PBS compared with controls with no effect of glutamine. Four proteins were more ubiquitinated in TNBS/PBS group and restored in TNBS/Gln group. Finally, 12 ubiquitinated proteins were only affected by glutamine. Among proteins affected by glutamine, eight proteins (GFPT1, Gapdh, Pkm2, LDH, Bcat2, ATP5a1, Vdac1, and Vdac2) were involved in metabolic pathways. In conclusion, glutamine may regulate ubiquitination process during intestinal inflammation.

Detection of immunogens from Fraxinus spp. pollen grains

This work is aimed at characterising immunogens from Fraxinus uhdei pollen and to develop ELISA assays for their immunodetection, since it is a relevant aeroallergen. F. uhdei pollen extract contained proteins in a wide range of molecular mass from 22 to 112 kDa by SDS-PAGE; moreover, 187 fractions were detected in the 2D electrophoresis. Pollen extract was used to generate rabbit hyperimmune serum. Western blot revealed six main immunogens in a range from 40 to 21 kDa and several protein spots in 2D immunoblot. Tryptic peptides from six spots were analysed by nano-LC-ESI-MS/MS, indicating that most of proteins show homology with proteins involved in metabolism and with Ole e 11 and Fra e 2. The minimum concentration of Fraxinus spp. proteins detected by ELISA assays was 0.25 μg/mL. The detection of one 21.5 KDa protein by WB in the dust obtained from air sampling suggests the possibility to be a Fraxinus spp. protein suspended in the atmosphere. ELISA assays of the air samples detected the higher concentrations of Fraxinus spp. proteins when its airborne pollen concentrations were higher, according to the Mexican Aerobiology Network.

Identification of immunoreactive proteins of Mycobacterium avium subsp. paratuberculosis.

Mycobacterium avium subsp. paratuberculosis (MAP) is the cause of a chronic enteritis of ruminants (bovine paratuberculosis (PTB)--Johne's disease) that is associated with enormous worldwide economic losses for the animal production. Diagnosis is based on observation of clinical signs, the detection of antibodies in milk or serum, or evaluation of bacterial culture from feces. The limit of these methods is that they are not able to detect the disease in the subclinical stage and are applicable only when the disease is already advanced. For this reason, the main purpose of this study is to use the MAP proteome to detect novel immunoreactive proteins that may be helpful for PTB diagnoses. 2DE and 2D immunoblotting of MAP proteins were performed using sera of control cattle and PTB-infected cattle in order to highlight the specific immunoreactive proteins. Among the assigned identifiers to immunoreactive spots it was found that most of them correspond to surface-located proteins while three of them have never been described before as antigens. The identification of these proteins improves scientific knowledge that could be useful for PTB diagnoses. The sequence of the identified protein can be used for the synthesis of immunoreactive peptides that could be screened for their immunoreaction against bovine sera infected with MAP. All MS data have been deposited in the ProteomeXchange consortium with identifier PXD001159 and DOI 10.6019/PXD001159.

Mitochondrial protein alterations in a familial peripheral neuropathy caused by the V144D amino acid mutation in the sphingolipid protein, SPTLC1.

Axonal degeneration is the final common path in many neurological disorders. Subsets of neuropathies involving the sensory neuron are known as hereditary sensory neuropathies (HSNs). Hereditary sensory neuropathy type I (HSN-I) is the most common subtype of HSN with autosomal dominant inheritance. It is characterized by the progressive degeneration of the dorsal root ganglion (DRG) with clinical symptom onset between the second or third decade of life. Heterozygous mutations in the serine palmitoyltransferase (SPT) long chain subunit 1 (SPTLC1) gene were identified as the pathogenic cause of HSN-I. Ultrastructural analysis of mitochondria from HSN-I patient cells has displayed unique morphological abnormalities that are clustered to the perinucleus where they are wrapped by the endoplasmic reticulum (ER). This investigation defines a small subset of proteins with major alterations in abundance in mitochondria harvested from HSN-I mutant SPTLC1 cells. Using mitochondrial protein isolates from control and patient lymphoblasts, and a combination of 2D gel electrophoresis, immunoblotting and mass spectrometry, we have shown the increased abundance of ubiquinol-cytochrome c reductase core protein 1, an electron transport chain protein, as well as the immunoglobulin, Ig kappa chain C. The regulation of these proteins may provide a new route to understanding the cellular and molecular mechanisms underlying HSN-I.

Abstract 5311: Proteomic characterization of zoledronic acid-resistant prostate cancer cells identified key proteins in cytoskeleton organization and cancer stem cell markers associated with a very aggressive phenotype

Abstract The aminobiphosphonate Zoledronic acid (ZOL) inhibit osteoclast-mediated bone resorption and it is used to prevent skeletal complications from bone metastases. Accumulating evidences in both preclinical and clinical studies indicated that ZOL might also have anticancer activity. We have recently selected for the first time the ZOL-resistant DU145R80 prostate cancer (PCa) cell line that demonstrated an antiapoptotic and proangiogenic phenotype with increased invasive capability and epithelial to mesenchymal transition (EMT), compared to parental DU145 cells. Interestingly, we also demonstrated that both the acquired resistance to ZOL and the aggressive phenotype are mediated by p38-MAPK (Milone et al. Cell Death Dis. 2013, 4:e641). To further investigate the mechanism of ZOL-resistance and of the parallel acquisition of an aggressive phenotype in this novel syngeneic model of PCa, we took advantage of a two-dimensional difference gel electrophoresis (2D-DIGE)/mass spectrometry (MS) proteomic approach, to investigate differential expressed proteins between DU145R80 and DU145 cell lines. We found 21 statistically differentially expressed protein spots between the two cell lines (average volume ratio threshold of ±1.4-fold and 95% level of significance, p&amp;lt;0.05) and 15 of these were identified by MS and validated by real-time PCR, 1D or 2D immunoblots. The identified proteins were involved in cell metabolism, cytoskeleton, nuclear lamina organization, protein fate and RNA processing, such as ALDH7A1, ANXA1, Lamin A/C, Filamin A, Lamin B2, PSMA6 and eEF1γ. Several of these proteins are related with the acquisition of a cancer stem cells (CSC) phenotype and indeed we showed in DU145R80 also the overexpression of additional prostate CSC markers such as Nanog, Oct-4, Snail and Integrin-aV. Furthermore, in DU145R80 compared to DU145 cells, we observed the increased presence of numerous podosomes/invadopodia and membrane bleb protrusions where FLNA clearly co-localize with actin. Interestingly, by using publicly available genomic data on PCa (http://www.oncomine.org) we demonstrated statistically significant higher expression of the genes codifying the identified proteins, in PCa vs normal tissues. Finally, proteomic results were further processed by interactome pathway analysis demonstrating a strong relationships between the identified proteins and additional effectors in both direct/indirect analysis, including p38-MAPK, and generating a relevant statistically significant network associated with cancer disease as well as with cellular movement and organization. Overall we confirmed that ZOL-resistant PCa cells developed an aggressive phenotype related with stemness feature and identified novel potential prognostic markers and/or therapeutic targets for PCa. Citation Format: Maria Rita Milone, Biagio Pucci, Federica Iannelli, Rita Lombardi, Katia Bifulco, Francesca Bruzzese, Elena Di Gennaro, Antonio Avallone, Maria Vincenza Carriero, Alfredo Budillon. Proteomic characterization of zoledronic acid-resistant prostate cancer cells identified key proteins in cytoskeleton organization and cancer stem cell markers associated with a very aggressive phenotype. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5311. doi:10.1158/1538-7445.AM2014-5311

Alpha 2HS-glycoprotein, a tumor-associated antigen (TAA) detected in Mexican patients with early-stage breast cancer.

In the present study, 2D immunoblot analysis was used to make a screening in samples of sera from patients with a diagnosis of early-stage breast cancer, in order to identify some autoantibodies that react against TAA. Proteins identified in the present study, particularly alpha 2HS-glycoprotein (AHSG), might be useful as potential biomarkers for breast cancer in early stages for Mexican populations.

A Cyanobacterial Chlorophyll Synthase-HliD Complex Associates with the Ycf39 Protein and the YidC/Alb3 Insertase

Macromolecular membrane assemblies of chlorophyll-protein complexes efficiently harvest and trap light energy for photosynthesis. To investigate the delivery of chlorophylls to the newly synthesized photosystem apoproteins, a terminal enzyme of chlorophyll biosynthesis, chlorophyll synthase (ChlG), was tagged in the cyanobacterium Synechocystis PCC 6803 (Synechocystis) and used as bait in pull-down experiments. We retrieved an enzymatically active complex comprising ChlG and the high-light-inducible protein HliD, which associates with the Ycf39 protein, a putative assembly factor for photosystem II, and with the YidC/Alb3 insertase. 2D electrophoresis and immunoblotting also provided evidence for the presence of SecY and ribosome subunits. The isolated complex contained chlorophyll, chlorophyllide, and carotenoid pigments. Deletion of hliD elevated the level of the ChlG substrate, chlorophyllide, more than 6-fold; HliD is apparently required for assembly of FLAG-ChlG into larger complexes with other proteins such as Ycf39. These data reveal a link between chlorophyll biosynthesis and the Sec/YidC-dependent cotranslational insertion of nascent photosystem polypeptides into membranes. We expect that this close physical linkage coordinates the arrival of pigments and nascent apoproteins to produce photosynthetic pigment-protein complexes with minimal risk of accumulating phototoxic unbound chlorophylls.

2D immunoblots show differential response of mouse IgG and IgM antibodies to antigens of mammary carcinoma 4 T1 cells

BackgroundImmunosuppression in breast cancer has been reported in women and in the highly metastatic mouse mammary tumor model 4 T1. The immunosuppressive environment complicates the use of the humoral response against the tumor as an immunodiagnostic tool. IgM has not been used in immunodiagnostic in part because its antitumor responses, both innate and adaptive, have not been studied in function of time in breast cancer.We show a new approach to analyzing the mouse humoral immune response, and compare the evolution with time of IgG and IgM responses against the antigens of 4 T1 cells.MethodsThe study is based on 2-dimensional immunoblotting detection of antigens from 4 T1 cells by the IgG and IgM antibodies in the serum of female mice injected with 4 T1 cells.ResultsThere was a high variability in the intra-and inter-mouse response. Variability in the IgM response was manifested as a pattern of spots that could become a multibinomial variable of 0 and 1, which could represent a signature of the immune response. Different numbers of spots was found in the IgG and IgM responses from week 1 to 5. On average, the IgM had more but the IgG response decrease with the time. The natural IgM at t = 0 responds stronger than w1; the adaptive response of both IgM and IgG were elicited where, with the former being stronger better than the latter. Antigens that are recognized by some female mice in the first week are also recognized by other female mice at time 0. Contamination of the natural IgM makes difficult use the adaptive IgM as a tool for immunodiagnostic.ConclusionsIgM and IgG response varied with the time and individuals. Spot variation in 2D pattern for the natural IgM could be expressed as a binomial signature, which opens up the way to correlate a particular pattern with resistance or susceptibility. This uncovers a battery of IgMs for each individual to confront cancer or infections. The possibility to differentiate between adaptive IgM antibodies from the natural IgM will allow investigation of the adaptive IgM for early immunodiagnosis.

P159 from Mycoplasma hyopneumoniae Binds Porcine Cilia and Heparin and Is Cleaved in a Manner Akin to Ectodomain Shedding

Mycoplasma hyopneumoniae colonizes the ciliated epithelial lining of the upper respiratory tract of swine and results in chronic infection. Previously, we have observed that members of P97 and P102 paralog families of cilium adhesins undergo endoproteolytic processing on the surface of M. hyopneumoniae. We show that P159 (MHJ_0494), an epithelial cell adhesin unrelated to P97 and P102 paralog families, is a cilium adhesin that undergoes dominant cleavage events at S/T-X-F↓X-D/E-like motifs located at positions (233)F↓Q(234) and (981)F↓Q(982), generating P27, P110, and P52. An unrelated cleavage site (738)L-K-V↓G-A-A(743) in P110 shows sequence identity with a cleavage site (L-N-V↓A-V-S) identified in the P97 paralog, Mhp385, and generates 76 (P76) and 35 kDa (P35) fragments. LC-MS/MS analysis of biotinylated surface proteins identified six peptides with a biotin moiety on their N-terminus indicating novel, low abundance neo-N-termini. LC-MS/MS of proteins separated by 2D-PAGE, 2D immunoblotting using monospecific antiserum raised against recombinant fragments spanning P159 (F1(P159)-F4(P159)), and proteins that bound to heparin-agarose were all used to map P159 cleavage fragments. P159 is the first cilium adhesin not belonging to the P97/P102 paralog families and is extensively processed in a manner akin to ectodomain shedding in eukaryotes.

Profiling Antibody Responses to Infections by Chlamydia abortus Enables Identification of Potential Virulence Factors and Candidates for Serodiagnosis

Enzootic abortion of ewes (EAE) due to infection with the obligate intracellular pathogen Chlamydia (C.) abortus is an important zoonosis leading to considerable economic loss to agriculture worldwide. The pathogen can be transmitted to humans and may lead to serious infection in pregnant women. Knowledge about epidemiology, clinical course and transmission to humans is hampered by the lack of reliable diagnostic tools. Immunoreactive proteins, which are expressed in infected animals and humans, may serve as novel candidates for diagnostic marker proteins and represent putative virulence factors. In order to broaden the spectrum of immunogenic C. abortus proteins we applied 2D immunoblot analysis and screening of an expression library using human and animal sera. We have identified 48 immunoreactive proteins representing potential diagnostic markers and also putative virulence factors, such as CAB080 (homologue of the “macrophage infectivity potentiator”, MIP), CAB167 (homologue of the “translocated actin recruitment protein”, TARP), CAB712 (homologue of the “chlamydial protease-like activity factor”, CPAF), CAB776 (homologue of the “Polymorphic membrane protein D”, PmpD), and the “hypothetical proteins” CAB063, CAB408 and CAB821, which are predicted to be type III secreted. We selected two putative virulence factors for further characterization, i.e. CAB080 (cMIP) and CAB063, and studied their expression profiles at transcript and protein levels. Analysis of the subcellular localization of both proteins throughout the developmental cycle revealed CAB063 being the first C. abortus protein shown to be translocated to the host cell nucleus.

Gel2DE - A software tool for correlation analysis of 2D gel electrophoresis data

BackgroundTwo-dimensional gel electrophoresis (2DE) is a powerful technique for studying protein isoforms and their modifications. Existing commercial 2D image analysis tools rely on spot detection that limits analysis of complex protein profiles, e.g. spot appearance/disappearance or overlapping spots. Pixel-by-pixel correlation analysis, an analysis technique for identifying relations between protein patterns in gel images and external variables, can overcome such limitations in spot analysis.ResultsWe have implemented the first publically available pixel-by-pixel correlation analysis tool, the software Gel2DE. 2D immunoblot time course analysis of p53 protein stabilization in response to ionizing irradiation shows that pixel-by-pixel analysis can yield an overall activation biosignature for p53, despite changing spots shape, size and position.ConclusionsPixel-by-pixel correlation of aligned 2D images permits analysis of complex protein patterns. We anticipate that the Gel2DE correlation software will be a useful tool for future bioinformatics discoveries through 2D gel electrophoresis.