Discovery of a Unique Set of Dog-Seroreactive Coccidioides Proteins Using Nucleic Acid Programmable Protein Array

Valley Fever (VF), caused by fungi in the genus Coccidioides, is a prevalent disease in southwestern and western parts of the United States that affects both humans and animals, such as dogs. Although the immune responses to infection with Coccidioides spp. are not fully characterized, antibody-detection assays are used in conjunction with clinical presentation and radiologic findings to aid in the diagnosis of VF. These assays often use Complement Fixation (CF) and Tube Precipitin (TP) antigens as the main targets of IgG and IgM reactivity, respectively. Our group previously reported evidence of over 800 genes expressed at the protein level in C. posadasii. However, antibody reactivity to the majority of these proteins has never been explored. Using a new, high-throughput screening technology, the Nucleic Acid Programmable Protein Array (NAPPA), we screened serum specimens from dogs against 708 of these previously identified proteins for IgG reactivity. Serum from three separate groups of dogs was analyzed and revealed a small panel of proteins to be further characterized for immuno-reactivity. In addition to CF/CTS1 antigen, sera from most infected dogs showed antibody reactivity to endo-1,3-betaglucanase, peroxisomal matrix protein, and another novel reactive protein, CPSG_05795. These antigens may provide additional targets to aid in antibody-based diagnostics.

Two lateral flow assays for detection of anti-coccidioidal antibodies show similar performance to immunodiffusion in dogs with coccidioidomycosis

OBJECTIVE

To compare 2 point-of-care lateral flow assays (LFAs) with immunodiffusion (ID) IgG results for anti-coccidioidal antibody detection in dogs with coccidioidomycosis. A further aim was to compare the quantifiable output of 1 of the LFAs to ID antibody titers.

SAMPLE

Serum banked from 73 client-owned dogs diagnosed with pulmonary or disseminated coccidioidomycosis.

METHODS

ID was used to determine antibody presence and titer against a coccidioidal antigen preparation. All sera were subsequently tested on an LFA based on recombinant chitinase 1 (CTS1) and the commercially available sōna LFA. LFA results were analyzed and compared to ID IgG results and clinical diagnosis.

RESULTS

All assays showed similar sensitivities in detecting anti-coccidioidal antibodies (83.6% to 89.0%). When compared with ID IgG, the CTS1 LFA had a positive percent agreement of 100%, while the sōna LFA had a positive percent agreement of 91.4%. Since the CTS1 LFA is semiquantitative, we were able to compare test line densities with ID titers and found a strong correlation between the 2 assays (Spearman ρ = 0.82).

CLINICAL RELEVANCE

This is the first side-by-side evaluation of a commercially available LFA (sōna) and a newer more rapid anti-CTS1 antibody LFA using serum from dogs with coccidioidomycosis. Both LFAs tested have similar sensitivity to ID IgG results. The CTS1 LFA can be read after 10 minutes and is semiquantitative, while the sōna LFA is read after 30 minutes, and the results are subject to interpretation. Accurate and fast detection of anti-coccidioidal antibodies allows clinicians to initiate appropriate treatment without diagnostic delay.

SETD2 loss in renal epithelial cells drives epithelial-to-mesenchymal transition in a TGF-β-independent manner

Histone-lysine N-methyltransferase SETD2 (SETD2), the sole histone methyltransferase that catalyzes trimethylation of lysine 36 on histone H3 (H3K36me3), is often mutated in clear cell renal cell carcinoma (ccRCC). SETD2 mutation and/or loss of H3K36me3 is linked to metastasis and poor outcome in ccRCC patients. Epithelial-to-mesenchymal transition (EMT) is a major pathway that drives invasion and metastasis in various cancer types. Here, using novel kidney epithelial cell lines isogenic for SETD2, we discovered that SETD2 inactivation drives EMT and promotes migration, invasion, and stemness in a transforming growth factor-beta-independent manner. This newly identified EMT program is triggered in part through secreted factors, including cytokines and growth factors, and through transcriptional reprogramming. RNA-seq and assay for transposase-accessible chromatin sequencing uncovered key transcription factors upregulated upon SETD2 loss, including SOX2, POU2F2 (OCT2), and PRRX1, that could individually drive EMT and stemness phenotypes in SETD2 wild-type (WT) cells. Public expression data from SETD2 WT/mutant ccRCC support the EMT transcriptional signatures derived from cell line models. In summary, our studies reveal that SETD2 is a key regulator of EMT phenotypes through cell-intrinsic and cell-extrinsic mechanisms that help explain the association between SETD2 loss and ccRCC metastasis.

Comparative proteomic analysis of tail regeneration in the green anole lizard, Anolis carolinensis

As amniote vertebrates, lizards are the most closely related organisms to humans capable of appendage regeneration. Lizards can autotomize, or release their tails as a means of predator evasion, and subsequently regenerate a functional replacement. Green anoles (Anolis carolinensis) can regenerate their tails through a process that involves differential expression of hundreds of genes, which has previously been analyzed by transcriptomic and microRNA analysis. To investigate protein expression in regenerating tissue, we performed whole proteomic analysis of regenerating tail tip and base. This is the first proteomic data set available for any anole lizard. We identified a total of 2,646 proteins - 976 proteins only in the regenerating tail base, 796 only in the tail tip, and 874 in both tip and base. For over 90% of these proteins in these tissues, we were able to assign a clear orthology to gene models in either the Ensembl or NCBI databases. For 13 proteins in the tail base, 9 proteins in the tail tip, and 10 proteins in both regions, the gene model in Ensembl and NCBI matched an uncharacterized protein, confirming that these predictions are present in the proteome. Ontology and pathways analysis of proteins expressed in the regenerating tail base identified categories including actin filament-based process, ncRNA metabolism, regulation of phosphatase activity, small GTPase mediated signal transduction, and cellular component organization or biogenesis. Analysis of proteins expressed in the tail tip identified categories including regulation of organelle organization, regulation of protein localization, ubiquitin-dependent protein catabolism, small GTPase mediated signal transduction, morphogenesis of epithelium, and regulation of biological quality. These proteomic findings confirm pathways and gene families activated in tail regeneration in the green anole as well as identify uncharacterized proteins whose role in regrowth remains to be revealed. This study demonstrates the insights that are possible from the integration of proteomic and transcriptomic data in tail regrowth in the green anole, with potentially broader application to studies in other regenerative models.

Development of a rapid lateral flow assay for detection of anti-coccidioidal antibodies

Coccidioides spp. are dimorphic fungi that are capable of infecting human and non-human mammals and can cause diverse manifestations of coccidioidomycosis or Valley fever (VF). In combination with clinical symptoms and radiographic findings, antibody-based diagnostic tests are often used to diagnose and monitor patients with VF. Chitinase 1 (CTS1) has previously been identified as the seroreactive antigen used in these diagnostic assays to detect anticoccidial IgG. Here, an indirect enzyme-linked immunosorbent assay to detect IgG to CTS1 demonstrated 165 of 178 (92.7%) patients with a positive result by immunodiffusion (ID) and/or complement fixation (CF) had antibodies to the single antigen CTS1. We then developed a rapid antibody lateral flow assay (LFA) to detect anti-CTS1 antibodies. Out of 143 samples tested, the LFA showed 92.9% positive percent agreement [95% confidence interval (CI), 84.3%-96.9%] and 97.7% negative percent agreement (95% CI, 87.9%-99.6%) with ID and CF assays. Serum or plasma from canines, macaques, and dolphins was also tested by the CTS1 LFA. Test line densities of the CTS1 LFA correlated in a linear manner with the reported CF and ID titers for human and non-human samples, respectively. This 10-min point-of-care test for the rapid detection of anti-coccidioidal antibodies could help to inform healthcare providers in real-time, potentially improving the efficiency of healthcare delivery.

Generation and characterization of a monoclonal antibody that binds to Galectin-1

Galectin-1 is a β-galactoside-binding lectin that has been implicated as a suppressive molecule in cancer and autoimmune diseases. Gal-1 has known immunomodulatory activity and was found to be expressed on regulatory T cells, leading to the potential for targeted immunotherapies. Anti-Gal-1 monoclonal antibodies were generated in this study using classical hybridoma techniques. MAb 6F3 was found to bind to Gal-1 by Western blot and ELISA. Flow cytometry was used to determine cell surface and intracellular binding of mAb 6F3 to Gal-1 in PBMC-derived Tregs and tumor cells, including Treg-like cell lines. These results suggest mAb 6F3 may be used to further study Gal-1 protein expression and function.

Volatile Metabolites in Lavage Fluid Are Correlated with Cytokine Production in a Valley Fever Murine Model

Coccidioides immitis and Coccidioides posadasii are soil-dwelling fungi of arid regions in North and South America that are responsible for Valley fever (coccidioidomycosis). Forty percent of patients with Valley fever exhibit symptoms ranging from mild, self-limiting respiratory infections to severe, life-threatening pneumonia that requires treatment. Misdiagnosis as bacterial pneumonia commonly occurs in symptomatic Valley fever cases, resulting in inappropriate treatment with antibiotics, increased medical costs, and delay in diagnosis. In this proof-of-concept study, we explored the feasibility of developing breath-based diagnostics for Valley fever using a murine lung infection model. To investigate potential volatile biomarkers of Valley fever that arise from host−pathogen interactions, we infected C57BL/6J mice with C. immitis RS (n = 6), C. posadasii Silveira (n = 6), or phosphate-buffered saline (n = 4) via intranasal inoculation. We measured fungal dissemination and collected bronchoalveolar lavage fluid (BALF) for cytokine profiling and for untargeted volatile metabolomics via solid-phase microextraction (SPME) and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). We identified 36 volatile organic compounds (VOCs) that were significantly correlated (p < 0.05) with cytokine abundance. These 36 VOCs clustered mice by their cytokine production and were also able to separate mice with moderate-to-high cytokine production by infection strain. The data presented here show that Coccidioides and/or the host produce volatile metabolites that may yield biomarkers for a Valley fever breath test that can detect coccidioidal infection and provide clinically relevant information on primary pulmonary disease severity.

Clinical Laboratory Utility of a Humanized Antibody in Commercially Available Enzyme Immunoassays for Coccidioidomycosis

Coccidioidomycosis, also called valley fever (VF), is a fungal infection with endemicity in desert regions of the western United States as well as certain arid regions of Central and South America. Laboratory-based diagnosis of VF often relies on the composite results from three serologic-based diagnostics, complement fixation, immunodiffusion, and enzyme immunoassay (EIA). EIA is commonly performed in clinical laboratories because results can be obtained in a few hours. Two commercially available EIAs, IMMY clarus Coccidioides antibody and Meridian Premier Coccidioides, look for the presence of anticoccidioidal IgG and IgM in patient sera that are diluted 1:441. Per regulatory requirements, this dilution step must be verified with a dilution step control despite not being provided as a reagent in either FDA-approved EIA kit. Therefore, clinical laboratories collect and reuse patient sera in subsequent tests that had a positive result in a previous test. This is a nonstandard process, reinforcing the need for a consistent and reliable dilution control. Here, we evaluate the performance of a humanized IgG and IgM antibody as a dilution control in both EIA kits. Both humanized IgG and IgM work well in each EIA and meet the appropriate threshold for positivity. IMPORTANCE In southwestern and western regions of the United States, at least half a million diagnostic tests for coccidioidomycosis (valley fever) are run annually. Enzyme immunoassays (EIAs) are blood tests which require precise dilution of patient serum prior to testing. To ensure patient serum is properly diluted, there is a regulatory requirement to ensure the dilution step is accurate. Two FDA-approved EIAs used to aid in the diagnosis of coccidioidomycosis do not contain controls for this dilution step, leaving clinical laboratories with the only option of using previously positive patient sera, which may not react in a reliable or predictable manner. Here, we evaluate a humanized monoclonal antibody against a coccidioidal antigen and its utility as a dilution control in both available commercial EIAs. The use of a humanized monoclonal antibody provides a standardized and well-characterized dilution control for use in serological assays that aid in diagnosis of coccidioidomycosis.

Longitudinal Comparison of Neutralizing Antibody Responses to COVID-19 mRNA Vaccines after Second and Third Doses

COVID-19 mRNA vaccines protect against severe disease and hospitalization. Neutralizing antibodies (NAbs) are a first-line defense mechanism, but protective NAb responses are variable. Currently, NAb testing is not widely available. This study employed a lateral flow assay for monitoring NAb levels postvaccination and natural infection, using a finger-stick drop of blood. We report longitudinal NAb data from BNT162b2 (Pfizer) and mRNA-1273 (Moderna) recipients after second and third doses. Results demonstrate a third dose of mRNA vaccine elicits higher and more durable NAb titers than the second dose, independent of manufacturer, sex, and age. Our analyses also revealed that vaccinated individuals could be categorized as strong, moderate, and poorly neutralizing responders. After the second dose, 34% of subjects were classified as strong responders, compared to 79% after the third dose. The final months of this study coincided with the emergence of the SARS-CoV-2 Omicron variant and symptomatic breakthrough infections within our study population. Lastly, we show that NAb levels sufficient for protection from symptomatic infection with early SARS-CoV-2 variants were not protective against Omicron infection and disease. This work highlights the need for accessible vaccine response monitoring for use in healthcare, such that individuals, particularly those in vulnerable populations, can make informed vaccination decisions.

Humanization and expression of IgG and IgM antibodies in plants as potential diagnostic reagents for Valley Fever

Monoclonal antibodies (mAbs) are important proteins used in many life science applications, from diagnostics to therapeutics. High demand for mAbs for different applications urges the development of rapid and reliable recombinant production platforms. Plants provide a quick and inexpensive system for producing recombinant mAbs. Moreover, when paired with an established platform for mAb discovery, plants can easily be tailored to produce mAbs of different isotypes against the same target. Here, we demonstrate that a hybridoma-generated mouse mAb against chitinase 1 (CTS1), an antigen from Coccidioides spp., can be biologically engineered for use with serologic diagnostic test kits for coccidioidomycosis (Valley Fever) using plant expression. The original mouse IgG was modified and recombinantly produced in glycoengineered Nicotiana benthamiana plants via transient expression as IgG and IgM isotypes with human kappa, gamma, and mu constant regions. The two mAb isotypes produced in plants were shown to maintain target antigen recognition to CTS1 using similar reagents as the Food and Drug Administration (FDA)-approved Valley Fever diagnostic kits. As none of the currently approved kits provide antibody dilution controls, humanization of antibodies that bind to CTS1, a major component of the diagnostic antigen preparation, may provide a solution to the lack of consistently reactive antibody controls for Valley Fever diagnosis. Furthermore, our work provides a foundation for reproducible and consistent production of recombinant mAbs engineered to have a specific isotype for use in diagnostic assays.

Development of a rapid point-of-care test that measures neutralizing antibodies to SARS-CoV-2

BACKGROUND

After receiving a COVID-19 vaccine, most recipients want to know if they are protected from infection and for how long. Since neutralizing antibodies are a correlate of protection, we developed a lateral flow assay (LFA) that measures levels of neutralizing antibodies from a drop of blood. The LFA is based on the principle that neutralizing antibodies block binding of the receptor-binding domain (RBD) to angiotensin-converting enzyme 2 (ACE2).

METHODS

The ability of the LFA was assessed to correctly measure neutralization of sera, plasma or whole blood from patients with COVID-19 using SARS-CoV-2 microneutralization assays. We also determined if the LFA distinguished patients with seasonal respiratory viruses from patients with COVID-19. To demonstrate the usefulness of the LFA, we tested previously infected and non-infected COVID-19 vaccine recipients at baseline and after first and second vaccine doses.

RESULTS

The LFA compared favorably with SARS-CoV-2 microneutralization assays with an area under the ROC curve of 98%. Sera obtained from patients with seasonal coronaviruses did not show neutralizing activity in the LFA. After a single mRNA vaccine dose, 87% of previously infected individuals demonstrated high levels of neutralizing antibodies. However, if individuals were not previously infected, only 24% demonstrated high levels of neutralizing antibodies after one vaccine dose. A second dose boosted neutralizing antibody levels just 8% higher in previously infected individuals, but over 63% higher in non-infected individuals.

CONCLUSIONS

A rapid, semi-quantitative, highly portable and inexpensive neutralizing antibody test might be useful for monitoring rise and fall in vaccine-induced neutralizing antibodies to COVID-19.

Development of a Quantitative Antigen Assay to Detect Coccidioidal Chitinase-1 (CTS1) in Human Serum

Background

Coccidioidomycosis is often diagnosed with a collection of tests that rely on the patient's ability to mount an immune response to the fungus (antibody-based diagnostics), making diagnosis of this infection challenging. Here we present an antigen-based assay that detects and quantifies coccidioidal chitinase-1 (CTS1) in human serum.

Methods

An inhibition-based enzyme-linked immunoassay (ELISA) was developed that utilizes a monoclonal antibody specific for coccidioidal CTS1. CTS1 was quantified in commercial antigen preparations using recombinant CTS1 as a standard. Sera from 192 individuals from an endemic area were tested, which included 78 patients (40.6%) with proven or probable coccidioidomycosis.

Results

The quantity of CTS1 in diagnostic commercial antigen preparations from different suppliers varied. CTS1 antigenemia was detected in 87.2% of patients with proven or probable coccidioidomycosis. Specificity was determined to be 96.94% using serum from individuals who reside in the Phoenix, Arizona area who did not have coccidioidomycosis. Levels of CTS1 correlated with low- and high-titer serology from patients with a coccidioidomycosis diagnosis.

Conclusions

Since the CTS1 inhibition ELISA described in this report does not depend on the host immune response, it is a promising diagnostic tool to aid in diagnosis and disease monitoring of coccidioidomycosis.

Carbo-loading in Coccidioides spp.: A quantitative analysis of CAZyme abundance and resulting glycan populations

Coccidioides spp. are important pneumonia-causing pathogens of the American southwest, but little is known about their glycobiology and how their glycosylations differ from other pneumonia-causing fungi. There is mounting preliminary evidence to suggest genus or even species-specific glycosylations in the fungal kingdom due to the presence of unique carbohydrate-active enzymes (CAZymes) in fungal genomes (Deshpande et al. 2008, Glycobiology, 18(8), 626-637; Karkowska-Kuleta and Kozik 2015, Acta Biochim Pol., 62(3), 339-351). If Coccidioides spp.-specific glycans can be identified, it may be possible to exploit these differences to develop more specific diagnostic approaches and more effective therapeutics. Herein, we i) mined Coccidioides spp. and other pathogenic fungal genomes to identify CAZymes specific for Coccidioides spp., ii) proteomically determined the Coccidioides spp. "CAZome" produced in vivo and in vitro, and iii) utilized glycomics to differentiate Coccidioides genus-specific N-glycans from other pathogenic fungi. As far as we are aware, this is the first proteomic and glycomic comparison of the N-glycomes and CAZomes of different fungal genera during infection in human hosts.

Molecular Inhibitor of QSOX1 Suppresses Tumor Growth In Vivo

Quiescin sulfhydryl oxidase 1 (QSOX1) is an enzyme overexpressed by many different tumor types. QSOX1 catalyzes the formation of disulfide bonds in proteins. Because short hairpin knockdowns (KD) of QSOX1 have been shown to suppress tumor growth and invasion in vitro and in vivo, we hypothesized that chemical compounds inhibiting QSOX1 enzymatic activity would also suppress tumor growth, invasion, and metastasis. High throughput screening using a QSOX1-based enzymatic assay revealed multiple potential QSOX1 inhibitors. One of the inhibitors, known as "SBI-183," suppresses tumor cell growth in a Matrigel-based spheroid assay and inhibits invasion in a modified Boyden chamber, but does not affect viability of nonmalignant cells. Oral administration of SBI-183 inhibits tumor growth in 2 independent human xenograft mouse models of renal cell carcinoma. We conclude that SBI-183 warrants further exploration as a useful tool for understanding QSOX1 biology and as a potential novel anticancer agent in tumors that overexpress QSOX1.

Evaluation of Virex® II 256 and Virex® Tb as Disinfectants of the Dimorphic Fungi Coccidioides immitis and Coccidioides posadasii

To date, limited published data exists regarding the efficacy of commonly used disinfectants in inactivating the Risk Group 3 dimorphic fungal pathogens, Coccidioides immitis and Coccidioides posadasii. Newer generation quaternary ammonium compounds, like Virex® II 256 and Virex® Tb, have not been previously evaluated. Herein, these disinfectants are evaluated against 10% bleach and 70% ethanol, for their ability to inactivate 5×10⁷ arthroconidial spores of C. immitis RS or C. posadasii strain Silveira within 2, 5, 10 or 20 minutes contact time in aqueous solution. Evidence is provided that both Virex® II 256 and Virex® Tb are highly effective alternatives to 10% bleach or 70% ethanol for the disinfection of 5×10⁷ arthroconidia of Coccidioides spp. within 2 minutes of contact time. 70% ethanol was seen as less effective in killing C.immitis RS arthroconidia and both 70% ethanol and 10% bleach were seen as less effective than the other disinfectants in killing C. posadasii strain Silveira, as longer contact times were required to completely inactivate the same number of arthroconidia.

Loss of SETD2 Induces a Metabolic Switch in Renal Cell Carcinoma Cell Lines toward Enhanced Oxidative Phosphorylation

SETD2, a histone H3 lysine trimethyltransferase, is frequently inactivated and associated with recurrence of clear cell renal cell carcinoma (ccRCC). However, the impact of SETD2 loss on metabolic alterations in ccRCC is still unclear. In this study, SETD2 null isogenic 38E/38F clones derived from 786-O cells were generated by zinc finger nucleases, and subsequent metabolic, genomic, and cellular phenotypic changes were analyzed by targeted metabolomics, RNA sequencing, and biological methods, respectively. Our results showed that compared with parental 786-O cells, 38E/38F cells had elevated levels of MTT/Alamar blue levels, ATP, glycolytic/mitochondrial respiratory capacity, citrate synthase (CS) activity, and TCA metabolites such as aspartate, malate, succinate, fumarate, and α-ketoglutarate. The 38E/38F cells also utilized alternative sources beyond pyruvate to generate acetyl-CoA for the TCA cycle. Moreover, 38E/38F cells showed disturbed gene networks mainly related to mitochondrial metabolism and the oxidation of fatty acids and glucose, which was associated with increased PGC1α, mitochondrial mass, and cellular size/complexity. Our results indicate that SETD2 deficiency induces a metabolic switch toward enhanced oxidative phosphorylation in ccRCC, which can be related to PGC1α-mediated metabolic networks. Therefore, this current study lays the foundation for the further development of a global metabolic analysis of cancer cells in individual patients, which ultimately will have significant potential for the discovery of novel therapeutics and precision medicine in SETD2-inactivated ccRCC.

Proteogenomic Re-Annotation of Coccidioides posadasii Strain Silveira

The aims of this study are to provide protein-based evidence upon which to reannotate the genome of Coccidiodes posadasii, one of two closely related species of Coccidioides, a dimorphic fungal pathogen that causes coccidioidomycosis, also called Valley fever. Proteins present in lysates and filtrates of in vitro grown mycelia and parasitic phase spherules from C. posadasii strain Silveira are analyzed using a GeLC-MS/MS method. Acquired spectra are processed with a proteogenomics workflow comprising a Silveira proteome database, a six-frame translation of the Silveira genome and an ab initio gene prediction tool prior to validation against published ESTs. This study provides evidence for 837 genes expressed at the protein level, of which 169 proteins (20.2%) are putative proteins and 103 (12.3%) are not annotated in the Silveira genome. Additionally, 275 novel peptides are derived from intragenic regions of the genome and 13 from intergenic regions, resulting in 172 gene refinements. Additionally, we are the first group to report translationally active retrotransposon elements in a Coccidioides spp. Our study reveals that the currently annotated genome of C. posadasii str. Silveira needs refinement, which is likely to be the case for many nonmodel organisms.

Total and Lectin-Binding Proteome of Spherulin from Coccidioides posadasii

Coccidioides is a virulent dimorphic fungus that causes coccidioidomycosis (valley fever) in mammals, including humans. Although the genome has been sequenced, a proteomic analysis does not exist. To address this gap in proteomic knowledge, we generated the proteome of spherulin (a well-studied lysate of fungal spherules) and identified 1390 proteins. Some of the proteins included glycosylation enzymes, which led us to hypothesize that fungal glycosylation patterns may be different from those of mammals and could be exploited to detect Coccidioides in tissues. We performed lectin-based immunohistochemistry on formalin-fixed paraffin-embedded human patients' lung tissues. GSL-II (Griffonia simplificonia lectin II) and sWGA (succinylated wheat germ agglutinin) lectins bound specifically to endospores and spherules in infected lungs. To identify lectin-binding glycoproteins in spherulin, we performed lectin-affinity chromatography, followed by LC-MS/MS. A total of 195 glycoproteins from spherulin bound to GSL-II, 224 glycoproteins bound to sWGA, and 145 glycoproteins bound to both lectins. This is the first report of the specific reactivity of GSL-II and sWGA lectins to Coccidioides endospores and spherules in infected human tissues and the first listing of the Coccidioidal proteome from spherulin using sequences present in three Coccidioides databases: RefSeq, SwissProt, and The Broad Institute's Coccidioides Genome project.

Ebselen inhibits QSOX1 enzymatic activity and suppresses invasion of pancreatic and renal cancer cell lines

Quiescin sulfhydryl oxidase 1 (QSOX1) is a highly conserved disulfide bond-generating enzyme that is overexpressed in diverse tumor types. Its enzymatic activity promotes the growth and invasion of tumor cells and alters extracellular matrix composition. In a nude mouse-human tumor xenograft model, tumors containing shRNA for QSOX1 grew significantly more slowly than controls, suggesting that QSOX1 supports a proliferative phenotype in vivo. High throughput screening experiments identified ebselen as an in vitro inhibitor of QSOX1 enzymatic activity. Ebselen treatment of pancreatic and renal cancer cell lines stalled tumor growth and inhibited invasion through Matrigel in vitro. Daily oral treatment with ebselen resulted in a 58% reduction in tumor growth in mice bearing human pancreatic tumor xenografts compared to controls. Mass spectrometric analysis of ebselen-treated QSOX1 mechanistically revealed that C165 and C237 of QSOX1 covalently bound to ebselen. This report details the anti-neoplastic properties of ebselen in pancreatic and renal cancer cell lines. The results here offer a “proof-of-principle” that enzymatic inhibition of QSOX1 may have clinical relevancy.

EUS-guided portal injection chemotherapy for treatment of hepatic metastases: feasibility in the acute porcine model

BACKGROUND AND AIMS

Direct injection of chemotherapy into the portal vein for treatment of liver metastases may increase hepatic tissue levels while decreasing systemic levels and toxicities. We aimed to evaluate EUS-guided portal injection chemotherapy (EPIC) by using drug-eluting microbeads or nanoparticles and compare it with systemic injection.

METHODS

We conducted a comparative feasibility trial in the acute porcine model (24 anesthetized pigs). Pigs were treated with irinotecan, doxorubicin, or albumin-bound paclitaxel nanoparticles (n = 8/group). Within each group, pigs were treated with EPIC or a systemic intravenous injection of drug and saline solution into the portal vein (n = 4/treatment). Irinotecan or doxorubicin were loaded onto microbeads for EPIC treatment only. We examined drug levels in tissue (1 hour) and plasma (15 minutes).

RESULTS

EUS-guided access and injection was successful in all animals. EPIC with irinotecan-loaded microbeads showed nearly double the hepatic concentration compared with systemic injection (6242 vs 3692 ng/g) and almost half the systemic levels. EPIC with doxorubicin-loaded microbeads showed a 5-fold increase in hepatic levels (35,450 vs 6930 ng/g) and a 30-fold decrease in cardiac levels (153 vs 4805 ng/g) compared with systemic administration (P < .05 for both). EPIC with albumin-bound paclitaxel nanoparticles increased hepatic concentrations by 60% and decreased systemic levels by 24% to 32%.

CONCLUSIONS

EPIC holds promise as a new treatment for hepatic metastases.

Distance from construction site and risk for coccidioidomycosis, Arizona, USA

Coccidioides spp. fungi, which are present in soil in the southwestern United States, can become airborne when the soil is disrupted, and humans who inhale the spores can become infected. In 2012, our institution in Maricopa County, Arizona, USA, began a building project requiring extensive excavation of soil. One year after construction began, we compared the acquisition of coccidioidomycosis in employees working adjacent to the construction site (campus A) with that of employees working 13 miles away (campus B). Initial testing indicated prior occult coccidioidal infection in 20 (11.4%) of 176 campus A employees and in 19 (13.6%) of 140 campus B employees (p = 0.55). At the 1-year follow-up, 3 (2.5%) of 120 employees from campus A and 8 (8.9%) of 90 from campus B had flow cytometric evidence of new coccidioidal infection (p = 0.04). The rate of coccidioidal acquisition differed significantly between campuses, but was not higher on the campus with construction.

Abstract 1790: Small molecule inhibitors of QSOX1 suppress tumor cell growth and invasion

Introduction:

QSOX1 is a flavin-dependent sulfhydryl oxidase and the only known human enzyme with both disulfide generating and transferring activities. Using tissue microarrays, we previously demonstrated that QSOX1 is over-expressed in multiple tumor types including breast, pancreas, prostate and myeloma. Loss of QSOX1 leads to a significant decrease in tumor cell proliferation and invasion. The over-expression of QSOX1 in tumor cells compared to non-malignant cells combined with its role in tumor cell proliferation and invasion make it an attractive target for potential anti-neoplastic agents.

Methods:

Using a high throughput screening assay to detect sulfhydryl oxidase activity, we screened a library of compounds for inhibition of the QSOX1 enzyme. We used ROS-GloTM, a luciferase-based assay that detects H2O2, to determine if any compounds in the library inhibited QSOX1-mediated disulfide bond formation using reduced RNAse A as a substrate. QSOX1 generates H2O2 as a by-product of disulfide bond formation. To determine if compounds that showed activity in the enzymatic assay were also active against tumor cells, we treated pancreatic, breast, and myeloma cells with the compounds in a dose-dependent fashion, using non-malignant cells as controls. We assayed growth/viability by MTT and CellTiter-Glo assays. Invasive activity of tumor cells was assessed using matrigel-coated inserts in a modified Boyden chamber assay.

Results:

High throughput library screening identified 4 compounds that specifically inhibited QSOX1 activity (designated A-D) compared to a glucose oxidase counter-screen. Growth/viability assays showed that compound D suppressed the growth of tumor cells with IC50s between 300nM-750nM, depending on tumor cell line. In non-malignant cells the IC50s for compound D were more than 10-fold higher than in tumor cells. Compounds A and D also inhibited invasion of breast and pancreatic tumor cells through Matrigel.

Conclusion:

This is the first report of chemical compounds that inhibit QSOX1 enzymatic activity. The discovery of QSOX1 inhibitors with cellular efficacy establishes the chemical tractability of the target. Our data demonstrate that these First-In-Class compounds have potential as anti-neoplastic therapeutics via inhibition of QSOX1.

Citation Format: Paul D. Hanavan, Douglas O. Faigel, Chen-Ting Ma, Eduard Sergienko, Nathalie Meurice, Joachim L. Petit, Yvette W. Ruiz, Benjamin A. Katchman, Douglas F. Lake. Small molecule inhibitors of QSOX1 suppress tumor cell growth and invasion. [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 1790. doi:10.1158/1538-7445.AM2014-1790

The emerging role of QSOX1 in cancer

SIGNIFICANCE

Quiescin sulfhydryl oxidase 1 (QSOX1) is an enzyme that oxidizes thiols during protein folding, reducing molecular oxygen to hydrogen peroxide. Tumor cells may take advantage of oxidative environments at different stages of tumorigenesis, but QSOX1 may also serve additional functions in tumors.

RECENT ADVANCES

Several groups have reported the over-expression of QSOX1 in breast, pancreas, and prostate cancers. A consensus is building that QSOX1 over-expression is important during tumor cell invasion, facilitating tumor cell migration at the tumor-stroma interface. As such, QSOX1 may be considered a prognostic indicator of metastatic potential or even indicate that cancer is present in a host.

CRITICAL ISSUES

However, some controversy exists between QSOX1 as a marker of poor or favorable outcome in breast cancer. More studies are required to reveal what advantage QSOX1 provides to breast and other types of cancer. More specifically, it is critical to learn which tumor types over-express QSOX1 and use its enzymatic activity to their advantage.

FUTURE DIRECTIONS

As interest increases in understanding the mechanisms of tumorigenesis within the extracellular matrix and how tumor cells influence fibroblasts and other stromal cells, QSOX1 may be revealed as an important player in cancer detection and prognosis. Defining the mechanism(s) of QSOX1 activity in tumors and in in vivo models will provide important insights into how to target QSOX1 with anti-neoplastic agents.

Oxidative protein folding: nature's knotty challenge

Oxidative protein folding (OPF) characterized by intramolecular disulfide bond formation is the most common and likely most ancient post-translational modification. Considering the number of proteins that a cell must fold correctly and the number of possible disulfide structures available to each protein, OPF represents a daunting biochemical permutation problem which is solved by relatively few oxidase and isomerase enzymes. A proper disulfide configuration provides the structural foundation for more nuanced intramolecular folding events that, ultimately, define protein activity. As such, control of OPF is critical to normal cell function and homeostasis. Ironically, when cells are stressed, the very process of OPF can generate reactive oxygen species, contributing to endoplasmic reticulum stress, inefficient protein folding, and initiation of the unfolded protein response-a phenomenon that induces pro-inflammatory signals which can contribute to metabolic and inflammatory diseases, neurodegenerative disease, and cancer. Contributing authors to this Forum of Antioxidants and Redox Signaling review the latest developments in our understanding of the complex and divergent processes that orchestrate OPF. New insights promise to offer improvements in both medicine and industrial biotechnology.

Expression of quiescin sulfhydryl oxidase 1 is associated with a highly invasive phenotype and correlates with a poor prognosis in Luminal B breast cancer

Introduction

Quiescin sulfhydryl oxidase 1 (QSOX1) oxidizes sulfhydryl groups to form disulfide bonds in proteins. Tumor specific expression of QSOX1 has been reported for numerous tumor types. In this study, we investigate QSOX1 as a marker of breast tumor progression and evaluate the role of QSOX1 as it relates to breast tumor growth and metastasis.

Methods

Correlation of QSOX1 expression with breast tumor grade, subtype and estrogen receptor (ER) status was gathered through informatic analysis using the "Gene expression based Outcome for Breast cancer Online" (GOBO) web-based tool. Expression of QSOX1 protein in breast tumors tissue microarray (TMA) and in a panel of breast cancer cell lines was used to confirm our informatics analysis. To investigate malignant cell mechanisms for which QSOX1 might play a key role, we suppressed QSOX1 protein expression using short hairpin (sh) RNA in ER+ Luminal A-like MCF7, ER+ Luminal B-like BT474 and ER- Basal-like BT549 breast cancer cell lines.

Results

GOBO analysis revealed high levels of QSOX1 RNA expression in ER+ subtypes of breast cancer. In addition, Kaplan Meyer analyses revealed QSOX1 RNA as a highly significant predictive marker for both relapse and poor overall survival in Luminal B tumors. We confirmed this finding by evaluation of QSOX1 protein expression in breast tumors and in a panel of breast cancer cell lines. Expression of QSOX1 in breast tumors correlates with increasing tumor grade and high Ki-67 expression. Suppression of QSOX1 protein slowed cell proliferation as well as dramatic inhibition of MCF7, BT474 and BT549 breast tumor cells from invading through Matrigel™ in a modified Boyden chamber assay. Inhibition of invasion could be rescued by the exogenous addition of recombinant QSOX1. Gelatin zymography indicated that QSOX1 plays an important role in the function of MMP-9, a key mediator of breast cancer invasive behavior.

Conclusions

Taken together, our results suggest that QSOX1 is a novel biomarker for risk of relapse and poor survival in Luminal B breast cancer, and has a pro-proliferative and pro-invasive role in malignant progression partly mediated through a decrease in MMP-9 functional activity.

Abstract P1-05-04: Expression of Quiescin Sulfhydryl Oxidase 1 is associated with a highly invasive phenotype and correlates with a poor prognosis in Luminal B breast cancer

Quiescin sulfhydryl oxidase 1 (QSOX1) oxidizes sulfhydryl groups to form disulfide bonds in proteins. Informatic analysis using the newly available “Gene Expression Based Outcome for Breast Cancer Online” (GOBO) tool indicated high levels of QSOX1 expression in Estrogen Receptor positive (ER+) subtypes of breast cancer. We confirmed this finding by evaluation of QSOX1 protein expression in breast tumors and in a panel of breast cancer cell lines. In addition, Kaplan Meyer analyses revealed QSOX1 as a significant predictive marker for both relapse and poor overall survival in Luminal B tumors, but not in other intrinsic subtypes. To investigate malignant cell mechanisms in which QSOX1 might play a key role, we suppressed QSOX1 protein expression using short hairpin (sh) RNA in ER+ MCF7 and ER− BT549 breast cancer cell lines. Suppression of QSOX1 protein dramatically slowed cell proliferation but did not significantly effect apoptosis or cell cycle regulation. Inhibition of QSOX1 did however dramatically inhibit MCF7 and BT549 breast tumor cells from invading through Matrigel in a modified Boyden chamber assay. Inhibition of invasion could be rescued by the exogenous addition of recombinant QSOX1. Gelatin zymography indicated that QSOX1 plays an important role in activation of MMP-9 a key mediator of breast cancer invasive behavior. Taken together, our results suggest that QSOX1 is a novel biomarker for risk of relapse and poor survival in Luminal B breast cancer, and has a pro-invasive role in malignant progression through post-translational activation of MMP-9.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-05-04.

CTL recognition of a novel HLA-A*0201-binding peptide derived from glioblastoma multiforme tumor cells

Genetic instability of tumor cells can result in translation of proteins that are out of frame, resulting in expression of neopeptides. These neopeptides are not self-proteins and therefore should be immunogenic. By eluting peptides from human glioblastoma multiforme (GBM) tumor cell surfaces and subjecting them to tandem mass spectrometry, we identified a novel peptide (KLWGLTPKVTPS) corresponding to a frameshift in the 3' beta-hydroxysteroid dehydrogenase type 7 (HSD3B7) gene. HLA-binding algorithms predicted that a 9-amino acid sequence embedded in this peptide would bind to HLA-A*0201. We confirmed this prediction using an HLA-A*0201 refolding assay followed by live cell relative affinity assays, but also showed that the 12-mer binds to HLA-A*0201. Based on the 9-mer sequence, optimized peptide ligands (OPL) were designed and tested for their affinities to HLA-A*0201 and their abilities to elicit anti-peptide and CTL capable of killing GBM in vitro. Wild-type peptides as well as OPL induced anti-peptide CTL as measured by IFN-γ ELISPOTS. These CTL also killed GBM tumor cells in chromium-51 release assays. This study reports a new CTL target in GBM and further substantiates the concept that rational design and testing of multiple peptides for the same T-cell epitope elicits a broader response among different individuals than single peptide immunization.

Risk factors for pancreatic adenocarcinoma and prospects for screening

Pancreatic cancer has one of the worst survival rates of any cancer and is the fourth leading cause of cancer mortality. Early detection and surgery are the patient's best chance for cure. However, symptoms are typically vague and occur when the cancer is unresectable. Population-based mass screening is not practical for this rare disease, though screening and early detection in asymptomatic high-risk patient populations may be indicated.

Discovery of a novel HLA-Cw*08 allele, Cw*0817

This report describes the discovery and characterization of the HLA-Cw*0817 allele.

Spherules derived from Coccidioides posadasii promote human dendritic cell maturation and activation

Previous studies have shown that dendritic cells (DC) pulsed with T27K, an antigenic preparation derived from spherules (of Coccidioides posadasii), activate peripheral blood mononuclear cells (PBMC) from nonimmune subjects as well as from patients with disseminated coccidioidomycosis. In this study, we have assessed the interaction between human DC and C. posadasii spherules in order to better understand the initial response between Coccidioides and the human host. Whole autoclaved spherules induced lymphocyte transformation in PBMC obtained from immune but not from nonimmune donors. Immature DC (iDC) bound fluorescein isothiocyanate-labeled spherules in a time- and temperature-dependent manner. This binding was blocked by the addition of mannan, suggesting mannose receptor involvement in the DC-Coccidioides interaction. Binding was subsequently associated with ingestion and intracellular processing of spherules. Coculturing of spherules with iDC was associated with the development of mature DC that were morphologically, phenotypically, and functionally similar to those induced by tumor necrosis factor alpha and prostaglandin E2. Finally, spherules incubated with iDC induced activation of PBMC from nonimmune donors. These data indicate that human DC are capable of binding, internalizing, and presenting antigens from Coccidioides spherules and suggest that DC may play a critical early role in the formation of a cellular immune response in human coccidioidomycosis.

The mannose receptor mediates the cellular immune response in human coccidioidomycosis

Mannose is the predominant monosaccharide in the coccidioidal antigen preparation T27K. Mannan and anti-CD206 antibody significantly decreased the surface expression of mannose receptor (MR) on adherent peripheral blood mononuclear cells and reduced the interleukin-2 (IL-2) release induced by T27K. These data suggest that MR mediates IL-2 release by T27K.

Inhibition of adherence and killing of Candida albicans with a 23-Mer peptide (Fn/23) with dual antifungal properties

Candida albicans adheres to host tissue and then proliferates in order to establish a commensal as well as a pathogenic state. Specific adherence to proteins is provided by several surface adhesins of Candida. Two well-studied proteins, Als1p and Als5p, do not require energy for adherence to occur (dead as well as living cells adhere) and have a multiplier effect of cell-cell aggregation that mediates the formation of microcolonies of Candida cells. The entire process is spontaneous, reversible, and stable for physiologically relevant chemical and physical forces. This adherence process is inhibited by the addition of free peptide ligands, including a 23-mer derived from fibronectin (Fn/23) that binds to the adhesins through H bond formation. Adherence was measured by determining the number of yeast cells that adhered to 90-microm-diameter polyethylene glycol (PEG) beads with a 7-mer peptide (KLRIPSV) synthesized on the surfaces of the beads. The concentration of the Fn/23 peptide that inhibited the adherence of cells to the peptide-coated beads by 50% was 4 to 5 microM, and the magnitudes of adherence were similar regardless of the presence or absence of physiologic salt concentrations. The minimum fungicidal concentration of Fn/23 was 2 to 4 microM in water, but there was no killing in physiologic salt concentrations. Peptides from the C and N termini or the center sequence of Fn/23 had no effect on inhibition of adherence and little effect on fungal viability. The fungicidal effect was similar to that seen with 23-, 19-, and 18-mer peptides derived from porcine myeloid cells, a Helicobacter pylori ribosomal protein, and a hybrid of cecropin and magainin, respectively. However, these fungicidal peptides did not inhibit C. albicans adherence to the peptide-coated PEG beads. This dual property of Fn/23, i.e., inhibition of adherence and killing of C. albicans, may provide important adjuvant effects in the treatment of disease caused by this fungus.

Increased activation-induced cell death in peripheral lymphocytes of rheumatoid arthritis patients: the mechanism of action

Recently, we have described a soluble survival signal for activated lymphocytes from CD14(+) cells. As a result of the importance of T lymphocytes in the pathogenesis of rheumatoid arthritis (RA), we speculate a possible role for CD14(+) cells in supporting the outgrowth of autoreactive lymphocytes in RA. To address this issue further, supernatants from activated CD14(+) cells (CD14 cocktails) in both normal controls and RA patients were collected. The relative strength of the CD14 cocktails from normal controls and RA patients was compared. The data showed that depletion of CD14(+) cells resulted in a much higher increase of activation-induced cell death (AICD) and a decrease of lymphocyte proliferation in the peripheral blood mononuclear cells of RA patients compared to normal controls. Interestingly, CD14 cocktails from RA patients provide much stronger protection against AICD compared to those from normal controls. The observed soluble survival signal from CD14(+) cells is a general phenomenon because CD14 cocktails prevent both phytohaemagglutinin A-p- and anti-CD3-induced AICD. Furthermore, supernatants collected from human dendritic cell cultures also prevent activated lymphocytes from undergoing AICD. The data implicate an important role of the CD14(+) cell and its secreted form of survival signal in the pathogenesis of RA.

Identification of HLA-Cw6.02 and HLA-Cw7.01 allele-specific binding motifs by screening synthetic peptide libraries

Unlike HLA-A and HLA-B, few peptide epitope motifs have been reported for HLA-C molecules. However, a number of cytotoxic T-lymphocyte epitopes derived from tumor antigens that bind to HLA-C molecules have been described. Here we report peptide-binding motifs for both HLA-Cw6.02 and HLA-Cw7.01 molecules. Recombinant human HLA molecules were generated and used to screen combinatorial 9mer peptide libraries. Complexes of HLA molecules properly folded and associated with beta2-microglobulin and peptides were identified using a conformation-specific HLA class I antibody conjugated to alkaline phosphatase. In the presence of substrate, peptide beads can be readily isolated and microsequenced to determine peptide identity. Of the peptides that bound to HLA-Cw6.02 and HLA-Cw7.01, 19 and 18 peptides, respectively, were sequenced, allowing motif identification for each C allele. This is the first report of an HLA-Cw7.01 peptide motif and extends the findings of Falk et al. [(1993) Proc Natl Acad Sci USA 90:12005] for an HLA-Cw6.02 motif. Anchoring amino acids for the HLA-Cw6.02 motif were phenylalanine or tyrosine in position (P)1, arginine in P2, and an aliphatic/aromatic residue at P9. Anchoring residues for HLA-Cw7.01 were positively charged amino acids in P1 and P2. Unlike most other HLA molecules, we were unable to assign P9 an anchoring residue, and we suspect that HLA-Cw7.01 binds peptides in an unconventional manner. Additionally, preferred amino acids were identified for both molecules. Identification of HLA-Cw6.02 and HLA-Cw7.01 peptide-binding motifs makes a significant contribution to the C allele peptide-binding motifs and will allow investigators to predict, design, and test HLA-Cw6.02 and HLA-Cw7.01 engineered peptides for immunotherapy.

Degenerate peptide recognition by Candida albicans adhesins Als5p and Als1p

Candida albicans and Saccharomyces cerevisiae expressing the adhesins Als5p or Als1p adhere to immobilized peptides and proteins that possess appropriate sequences of amino acids in addition to a sterically accessible peptide backbone. In an attempt to further define the nature of these targets, we surveyed the ability of yeast cells to adhere to 90- micro m-diameter polyethylene glycol beads coated with a 7-mer peptide from a library of 19(7) unique peptide-beads. C. albicans bound to ca. 10% of beads from the library, whereas S. cerevisiae expressing Als5p or Als1p bound to ca. 0.1 to 1% of randomly selected peptide-beads. S. cerevisiae expressing Als1p had a distinctly different adherence phenotype than did cells expressing Als5p. The former adhered in groups or clumps of cells, whereas the latter adhered initially as single cells, an event which was followed by the build up of cell-cell aggregates. Beads with adherent cells were removed, and the peptide attached to the bead was determined by amino acid sequencing. All adhesive beads carried a three-amino-acid sequence motif (tau phi+) that possessed a vast combinatorial potential. Adherence was sequence specific and was inhibited when soluble peptide identical to the immobilized peptide was added. The Als5p adhesin recognized some peptides that went unrecognized by Als1p. The sequence motif of adhesive peptides identified by this method is common in proteins and offers so many possible sequence combinations that target recognition by the Als proteins is clearly degenerate. A degenerate recognition system provides the fungi with the potential of adhering to a multitude of proteins and peptides, an advantage for any microorganism attempting to establish a commensal or pathogenic relationship with a host.

Her-2/ neu altered peptide ligand-induced CTL responses: implications for peptides with increased HLA affinity and T-cell-receptor interaction

In this study, we developed two Her-2/ neu-derived E75 altered peptide ligands (APLs) that demonstrate increased affinities for the HLA-A*0201 allele compared with wild-type E75 peptide. The APLs contain amino acids from E75(369-377), an immunodominant Her-2/ neu-derived peptide, and preferred primary and auxiliary HLA-A*0201 molecule anchor residues previously identified from combinatorial peptide library screening with the recombinant molecule. CTL lines were generated against wild-type E75 peptide (KIFGSLAFL) and APLs by multiple rounds of peptide stimulation of peripheral blood mononuclear cells (PBMCs) from HLA-A2+ antigen normal individuals. CTL lines raised on wild-type E75 peptide cross-reacted with APLs and similarly, CTL lines raised on APLs cross-reacted with wild-type E75 peptide, as measured by IFN-gamma ELISpot and target cell lysis assays. One of five individuals demonstrated specificity for APL 2 (FLFGSLAFL), whereas APL 5 (FLFESLAFL)-specific responses were observed from all five individuals tested. Molecular models of the E75, APL 2, and APL 5/HLA-A2 complexes indicated that the substitution of glycine with glutamic acid at position four of APL 5 resulted in the presentation of a large, negatively charged side chain that interacts with the outer edge of the HLA-A2 antigen alpha helix and is freely available to interact with cognate T-cell receptors. The results of this study further substantiate the concept that rational design of T-cell epitopes may lead to stronger peptide immunogens than natural, wild-type peptides.

Molecular profile of the T cell receptors of regulatory and effector CD4+ T cells recognizing overlapping determinants on glutamic acid decarboxylase (524–543)

Glutamic acid decarboxylase (GAD65) is one of the autoantigens that initiates pathogenic T cell responses against insulin-secreting pancreatic beta cells in Type 1 diabetes (T1D). Previously it was shown that spontaneously arising pathogenic T cell responses in the NOD mouse model are confined to GAD530-543 (p530). However, regulatory T cell subpopulations, which can prevent diabetes, can also be generated, for example, by immunization with GAD524-538 (p524) or GAD524-543. Interestingly, two functionally distinct subpopulations of T cells which recognize overlapping determinants of GAD524-543, p524 and p530, utilize distinct TCR Vbeta families, Vbeta4 for pathogenic, and Vbeta12 for regulatory T cells. We characterized T cell receptors (TCRs) from each subpopulation of T cells and visualized p524-specific TCR/p524/I-A(g7) and p530-specific TCR/p530/I-A(g7) complexes via molecular modeling to help us understand, at a molecular level, the in vivo expansion of p524- or p530-specific T cells in the NOD model of T1D. The absolute restriction in Vbeta usage but not Valpha usage and conserved CDR3beta lengths for both T cell subpopulations demonstrates that the beta chains are main contributors in shaping both p524/I-A(g7) and p530/I-A(g7) restricted TCRs. However, only Vbeta4+ T cells but not Vbeta12+ T cells contain a common motif (DWG) in CDR3beta and may involve all of CDR1beta, CDR2beta, and CDR3beta in the recognition of the C-terminus of p530. These observations imply that the spontaneously arising p530-restricted TCRs may be selected under stringent structural frameworks to bind p530/I-A(g7) with high affinity. Thus, the pathogenic p530-specific T cells may arise from a small pool of autoreactive T cells upon breaking tolerance.

Functional characterization of CTL against gp100 altered peptide ligands

In this study, four modified gp100 peptides were designed by combining amino acids from the melanoma peptide antigen gp100((209-217)) with preferred primary and auxiliary HLA-A *0201 anchor residues previously identified from combinatorial peptide library screening with recombinant HLA-A*0201. These modified peptides demonstrated stronger binding affinity for the HLA-A*0201 molecule compared to wild-type gp100 peptide. Nine CTL lines generated from patients immunized with the g209-2 M peptide and one CTL line from a non-immunized patient were tested for the ability to respond to these modified gp100 peptides. Stimulation of CTL by two of four modified peptides induced higher levels of IFN-gamma secretion than the wild-type gp100 peptide, demonstrating that higher peptide binding affinity for HLA molecules does not necessarily equate to functional activity of CTL. Two major and one minor CTL recognition pattern were observed, irrespective of previous peptide immunization, suggesting that multiple, rationally designed modified tumor peptides for the same epitope stimulate a broad CTL response by activating multiple CTL capable of cross-reacting with the natural antigenic peptide.

Reversal of coccidioidal anergy in vitro by dendritic cells from patients with disseminated coccidioidomycosis

Coccidioides immitis is a pathogenic, dimorphic fungus found in the southwestern United States and is the causative agent of coccidioidomycosis. Extrathoracic dissemination of coccidioidomycosis is associated with a lack of cellular immunity. Dendritic cells (DCs) have been shown to initiate and modulate cellular immune responses. To determine whether DCs could modulate or initiate the immune response in this disease, monocyte-derived DCs were generated from coccidioidal Ag nonresponsive patients with disseminated coccidioidomycosis and healthy nonimmune individuals. DCs generated from both groups demonstrated phenotypes characteristic of DCs and stimulated strong allogeneic MLR. DCs from patients and healthy nonimmune individuals pulsed with the coccidioidal Ag preparation T27K induced lymphocyte proliferation. Mature DCs were much more efficient than immature DCs in these stimulations. Furthermore, restimulation of T27K-primed PBMC with Ag-pulsed DCs generated a C. immitis-specific cellular immune response in PBMC from patients with disseminated coccidioidomycosis as well as healthy nonimmune individuals. These results show that 1) DCs have the capacity to stimulate specific cellular immune responses from patients with disseminated coccidioidomycosis who are nonresponsive to coccidioidal Ag and healthy nonimmune individuals in vitro; 2) DCs can be used to screen coccidioidal Ags as candidates for human vaccine development; and 3) DC therapy may be useful in the treatment of disseminated coccidioidomycosis.

Antigen presentation of a modified tumor-derived peptide by tumor infiltrating lymphocytes

CD8+ T-lymphocytes recognize peptides in the context of major histocompatibility complex (MHC) class I antigens. Upon activation, these cells differentiate into effector cytotoxic T lymphocytes (CTL) and no longer require formal antigen presentation by professional antigen presenting cells (APC). Subsequently, any cell expressing MHC class I/cognate peptide can stimulate CTL. Using TIL specific for a melanoma antigen-derived peptide, IMDQVPFSV (g209 2M), we sought to determine whether these CTL could present peptide to each other. Our findings demonstrate that peptide presentation of the g209 2M peptide epitope by TIL is comparable to conventional methods of using T2 cells as APC. We report here that CTL are capable of self-presentation of antigenic peptide to neighboring CTL resulting in IFN-gamma secretion, proliferation, and lysis of peptide-loaded CTL. These results demonstrate that human TIL possess both APC functions as well as cytotoxic functions and that this phenomenon could influence CTL activity elicited by immunotherapy.

Dendritic cells pulsed with Coccidioides immitis lysate induce antigen-specific naive T cell activation

Coccidioidomycosis, an infection endemic to the southwestern United States, is caused by the fungus Coccidioides immitis. Coccidioidal infection is overcome by the development of cell-mediated immunity. This study evaluated the role of dendritic cells (DCs) in the initiation of coccidioidal immunity in nonimmune individuals. It was demonstrated that DCs pulsed with the coccidioidal antigen preparation, toluene spherule lysate (TSL), induce DC maturation, autologous lymphocyte proliferation, and antigen-specific lymphocyte responses from nonimmune donors. Furthermore, TSL-primed lymphocytes secreted interferon-gamma after restimulation with TSL or antigen 2/proline-rich antigen, a subcomponent of TSL, but they did not do so when restimulated with ovalbumin or unpulsed DCs. The results demonstrate that DCs generated from individuals not exposed to C. immitis can specifically prime lymphocytes for coccidioidal antigens and that the response generated by the lymphocytes is characteristic of a cellular immune response.

Construction and binding analysis of recombinant single-chain TCR derived from tumor-infiltrating lymphocytes and a cytotoxic T lymphocyte clone directed against MAGE-1

The TCR is responsible for the specificity of cytotoxic T lymphocytes (CTL) by recognizing peptides presented in the context of MHC. By producing recombinant soluble TCR, it is possible to study this interaction at the molecular level. We generated single-chain TCR (scTCR) from tumor infiltrating lymphocytes (TIL) and one CTL clone directed against melanoma-associated antigen (MAGE)-1. Sixty-eight day anti-MAGE-1 TIL and one cloned anti-MAGE-1 CTL were analyzed by PCR for their Valpha and Vbeta gene usage. The TIL population showed a restriction in Valpha and Vbeta usage with only Valpha4 and Valpha9 and Vbeta2 and Vbeta7 expressed. The anti-MAGE-1 CTL clone demonstrated absolute restriction with only Valpha12 and Vbeta1 expressed. DNA sequence analysis was performed on all V regions. For the TIL, each possible Valpha-Vbeta combination (i.e. Valpha4-Vbeta2, Valpha9-Vbeta2, Valpha4-Vbeta7 and Valpha9-Vbeta7) was constructed as a distinct scTCR and the recombinant proteins expressed in bacteria. From the anti-MAGE-1 TIL, Valpha4-Vbeta2 scTCR demonstrated binding activity to HLA-A1(+) cells pulsed with MAGE-1 peptide. Results obtained from screening a panel of our scTCR constructs on HLA-A1(+) cells pulsed with MAGE-1 peptide or irrelevant peptide demonstrated that Vbeta2 plays a significant role in binding to the MAGE-1 peptide. Amino acid alignment analysis showed that each Vbeta sequence is distinctly different from the others. These findings demonstrate that soluble TCR in single-chain format have binding activity. Furthermore, the results indicate that in TCR, like antibodies, one chain may contribute a dominant portion of the binding activity.

Recognition of defined epitopes by affinity-purified anti-immunoglobulin fab autoantibodies isolated from HIV-infected humans

Infection of humans with HIV-1 has previously been independently shown to result in the generation of autoantibodies (AAbs) reactive with immunoglobulin Fab fragments (Heidelberg), and with autoantibodies to T-cell receptors (TCRs) (Tucson). Here, we carry out epitope mapping studies of affinity-purified AAbs to Fab fragments prepared from individual HIV-positive patients for their capacity to bind recombinant constructs and peptide-defined epitopes modeling TCR and Ig light chains. Some affinity-purified autoantibodies reacted strongly with TCRs expressed by intact T-cells, and recombinant Valpha/Vbeta constructs as well as with certain synthetic peptide epitopes. The binding reactions of affinity-purified AAbs of individual patients were distinct, and the AAb preparations consisted of populations of polyclonal lgs as reflected in specificity and isotype. AAb pools from individual patients all bound particular regions of TCR and Ig chains defined by comprehensive peptide synthesis including the CDR1 and Fr3 segments of the variable domains and the joining segment/switch peptide. In addition, other reactivities to restricted regions of alpha, beta and lambda light chains were documented. These results substantiate the cross-reactivity of TCR and Ig-Fab determinants, and are consistent with the hypothesis that autoantibodies arising as a consequence of HIV infection can have an immunomodulatory role.