A flow cytometry-based assay to determine the ability of anti-Streptococcus pyogenes antibodies to mediate monocytic phagocytosis in human sera

Streptococcus pyogenes, commonly referred to as Group A Streptococcus (Strep A), causes a spectrum of diseases, with the potential to progress into life-threatening illnesses and autoimmune complications. The escalating threat of antimicrobial resistance, stemming from the prevalent reliance on antibiotic therapies to manage Strep A infections, underscores the critical need for the development of disease control strategies centred around vaccination. Phagocytes play a critical role in controlling Strep A infections, and phagocytosis-replicating assays are essential for vaccine development. Traditionally, such assays have employed whole-blood killing or opsonophagocytic methods using HL-60 cells as neutrophil surrogates. However, assays mimicking Fcγ receptors- phagocytosis in clinical contexts are lacking. Therefore, here we introduce a flow cytometry-based method employing undifferentiated THP-1 cells as monocytic/macrophage model to swiftly evaluate the ability of human sera to induce phagocytosis of Strep A. We extensively characterize the assay's precision, linearity, and quantification limit, ensuring robustness. By testing human pooled serum, the assay proved to be suitable for the comparison of human sera's phagocytic capability against Strep A. This method offers a valuable complementary assay for clinical studies, addressing the gap in assessing FcγR-mediated phagocytosis. By facilitating efficient evaluation of Strep A -phagocyte interactions, it may contribute to elucidating the mechanisms required for the prevention of infections and inform the development of future vaccines and therapeutic advancements against Strep A infections.

Development and characterization of a hemolysis inhibition assay to determine functionality of anti-Streptolysin O antibodies in human sera

The high burden of disease and the long-lasting sequelae following Streptococcus pyogenes (Strep A) infections make the development of an effective vaccine a global health priority. Streptolysin O (SLO), is a key toxin in the complex pathogenesis of Strep A infection. Antibodies are elicited against SLO after natural exposure and represent a key target for vaccine-induced immunity. Here we present the setup and characterization of a hemolysis assay to measure functionality of anti-SLO antibodies in human sera. Assay specificity, precision, linearity, reproducibility, and repeatability were determined. The assay was demonstrated to be highly sensitive, specific, reproducible, linear and performed well in assessing functionality of anti-SLO antibodies induced by exposed individuals. Moreover, different sources of critical reagents, in particular red- blood cells, have been compared and had minimal impact on assay performance. The assay presented here has throughput suitable for evaluating sera in vaccine clinical trials and sero-epidemiological studies to gain further insights into the functionality of infection- and vaccine-induced antibodies.

Testing a Recombinant Form of Tetanus Toxoid as a Carrier Protein for Glycoconjugate Vaccines

Glycoconjugate vaccines play a major role in the prevention of infectious diseases worldwide, with significant impact on global health, enabling the polysaccharides to induce immunogenicity in infants and immunological memory. Tetanus toxoid (TT), a chemically detoxified bacterial toxin, is among the few carrier proteins used in licensed glycoconjugate vaccines. The recombinant full-length 8MTT was engineered in E. coli with eight individual amino acid mutations to inactivate three toxin functions. Previous studies in mice showed that 8MTT elicits a strong IgG response, confers protection, and can be used as a carrier protein. Here, we compared 8MTT to traditional carrier proteins TT and cross-reactive material 197 (CRM197), using different polysaccharides as models: Group A Streptococcus cell-wall carbohydrate (GAC), Salmonella Typhi Vi, and Neisseria meningitidis serogroups A, C, W, and Y. The persistency of the antibodies induced, the ability of the glycoconjugates to elicit booster response after re-injection at a later time point, the eventual carrier-induced epitopic suppression, and immune interference in multicomponent formulations were also evaluated. Overall, immunogenicity responses obtained with 8MTT glycoconjugates were compared to those obtained with corresponding TT and, in some cases, were higher than those induced by CRM197 glycoconjugates. Our results support the use of 8MTT as a good alternative carrier protein for glycoconjugate vaccines, with advantages in terms of manufacturability compared to TT.

Streptococcus pyogenes Colonization in Children Aged 24-59 Months in the Gambia: Impact of Live Attenuated Influenza Vaccine and Associated Serological Responses

BACKGROUND

Immunity to Streptococcus pyogenes in high burden settings is poorly understood. We explored S. pyogenes nasopharyngeal colonization after intranasal live attenuated influenza vaccine (LAIV) among Gambian children aged 24-59 months, and resulting serological response to 7 antigens.

METHODS

A post hoc analysis was performed in 320 children randomized to receive LAIV at baseline (LAIV group) or not (control). S. pyogenes colonization was determined by quantitative polymerase chain reaction (qPCR) on nasopharyngeal swabs from baseline (day 0), day 7, and day 21. Anti-streptococcal IgG was quantified, including a subset with paired serum before/after S. pyogenes acquisition.

RESULTS

The point prevalence of S. pyogenes colonization was 7%-13%. In children negative at day 0, S. pyogenes was detected at day 7 or 21 in 18% of LAIV group and 11% of control group participants (P = .12). The odds ratio (OR) for colonization over time was significantly increased in the LAIV group (day 21 vs day 0 OR, 3.18; P = .003) but not in the control group (OR, 0.86; P = .79). The highest IgG increases following asymptomatic colonization were seen for M1 and SpyCEP proteins.

CONCLUSIONS

Asymptomatic S. pyogenes colonization appears modestly increased by LAIV, and may be immunologically significant. LAIV could be used to study influenza-S. pyogenes interactions. Clinical Trials Registration. NCT02972957.

Exploring the Role of GMMA Components in the Immunogenicity of a 4-Valent Vaccine against Shigella

Shigellosis is the leading cause of diarrheal disease, especially in children of low- and middle-income countries, and is often associated with anti-microbial resistance. Currently, there are no licensed vaccines widely available against Shigella, but several candidates based on the O-antigen (OAg) portion of lipopolysaccharides are in development. We have proposed Generalized Modules for Membrane Antigens (GMMA) as an innovative delivery system for OAg, and a quadrivalent vaccine candidate containing GMMA from S. sonnei and three prevalent S. flexneri serotypes (1b, 2a and 3a) is moving to a phase II clinical trial, with the aim to elicit broad protection against Shigella. GMMA are able to induce anti-OAg-specific functional IgG responses in animal models and healthy adults. We have previously demonstrated that antibodies against protein antigens are also generated upon immunization with S. sonnei GMMA. In this work, we show that a quadrivalent Shigella GMMA-based vaccine is able to promote a humoral response against OAg and proteins of all GMMA types contained in the investigational vaccine. Proteins contained in GMMA provide T cell help as GMMA elicit a stronger anti-OAg IgG response in wild type than in T cell-deficient mice. Additionally, we observed that only the trigger of Toll-like Receptor (TLR) 4 and not of TLR2 contributed to GMMA immunogenicity. In conclusion, when tested in mice, GMMA of a quadrivalent Shigella vaccine candidate combine both adjuvant and carrier activities which allow an increase in the low immunogenic properties of carbohydrate antigens.

Elucidating the role of N-acetylglucosamine in Group A Carbohydrate for the development of an effective glycoconjugate vaccine against Group A Streptococcus

Group A Carbohydrate (GAC), conjugated to an appropriate carrier protein, has been proposed as an attractive vaccine candidate against Group A Streptococcus infections. Native GAC consists of a polyrhamnose (polyRha) backbone with N-acetylglucosamine (GlcNAc) at every second rhamnose residue. Both native GAC and the polyRha backbone have been proposed as vaccine components. Here, chemical synthesis and glycoengineering were used to generate a panel of different length GAC and polyrhamnose fragments. Biochemical analyses were performed confirming that the epitope motif of GAC is composed of GlcNAc in the context of the polyrhamnose backbone. Conjugates from GAC isolated and purified from a bacterial strain and polyRha genetically expressed in E. coli and with similar molecular size to GAC were compared in different animal models. The GAC conjugate elicited higher anti-GAC IgG levels with stronger binding capacity to Group A Streptococcus strains than the polyRha one, both in mice and in rabbits. This work contributes to the development of a vaccine against Group A Streptococcus suggesting GAC as preferable saccharide antigen to include in the vaccine.

Antigen presentation by Follicular Dendritic cells to cognate B cells is pivotal for Generalised Modules for Membrane Antigens (GMMA) immunogenicity

GMMA has been proposed as a potent technology platform for the design of safe, effective and affordable vaccines. As GMMA are vesicles blebbing out of the outer membrane of Gram-negative bacteria, they contain lipopolysaccharides, lipoproteins and peptidoglycans that stimulate immune cells via Toll-like Receptors 4 (TLR4) or TLR2. Being basically nanoparticles, GMMA can be efficiently captured by Follicular Dendritic Cells (FDC) for antigen presentation to cognate B cells. GMMA have shown to be highly immunogenic in preclinical and clinical studies and the engagement of TLR4 and TLR2 or antigen presentation by FDC may have a prominent role in GMMA immunogenicity, which is well worth investigating. By using GMMA derived from Shigella sonnei and Salmonella Typhimurium, we show for the first time that the antigen presentation by FDC to cognate B cells plays a major role in the induction of an effective humoral immune response upon immunization with GMMA by using both models. The engagement of TLR4 is critical to elicit an optimal antibody production, but its effect on antibody functionality is dependent on GMMA type and is dispensable when immunizing with Alum adjuvant, whereas TLR2 does not have any role for GMMA immunogenicity. Our findings represent a substantial advancement of the knowledge on GMMA mode of action and shed a light on novel perspectives for the design of safer and more effective GMMA-based vaccines. ONE SENTENCE SUMMARY: The study demonstrated that the antigen presentation by FDC to cognate B cells plays a major role for GMMA immunogenicity.

Investigating the Role of Antigen Orientation on the Immune Response Elicited by Neisseria meningitidis Factor H Binding Protein on GMMA

GMMA are outer membrane vesicles (OMVs) released from Gram-negative bacteria genetically modified to enhance OMVs formation that have been shown to be optimal systems to enhance immunogenicity of protein antigens. Here, we selected Neisseria meningitidis factor H binding protein (fHbp) and used the conjugation chemistry as a tool to alter antigen orientation on GMMA. Indeed, fHbp was randomly linked to GMMA or selectively attached via the N-terminus to mimic native presentation of the protein on the bacterial surface. Interestingly, protein and peptide array analyses confirmed that antibodies induced by the selective and the random conjugates showed a pattern very similar to fHbp natively expressed on bacterial surfaces or to the recombinant protein mixed with GMMA, respectively. However, the two conjugates elicited antibodies with similar serum bactericidal activity against meningococcal strains, superior to the protein alone or physically mixed with GMMA. Presentation of fHbp on GMMA strongly enhances the functional immune response elicited by the protein but its orientation on the bacterial surface does not have an impact. This study demonstrates the flexibility of the GMMA platform as a display and delivery system for enhancing antigen immunogenicity and further supports the use of such promising technology for the development of effective vaccines.

GMMA as an Alternative Carrier for a Glycoconjugate Vaccine against Group A Streptococcus

Group A Streptococcus (GAS) causes about 500,000 annual deaths globally, and no vaccines are currently available. The Group A Carbohydrate (GAC), conserved across all GAS serotypes, conjugated to an appropriate carrier protein, represents a promising vaccine candidate. Here, we explored the possibility to use Generalized Modules for Membrane Antigens (GMMA) as an alternative carrier system for GAC, exploiting their intrinsic adjuvant properties. Immunogenicity of GAC-GMMA conjugate was evaluated in different animal species in comparison to GAC-CRM197; and the two conjugates were also compared from a techno-economic point of view. GMMA proved to be a good alternative carrier for GAC, resulting in a higher immune response compared to CRM197 in different mice strains, as verified by ELISA and FACS analyses. Differently from CRM197, GMMA induced significant levels of anti-GAC IgG titers in mice also in the absence of Alhydrogel. In rabbits, a difference in the immune response could not be appreciated; however, antibodies from GAC-GMMA-immunized animals showed higher affinity toward purified GAC antigen compared to those elicited by GAC-CRM197. In addition, the GAC-GMMA production process proved to be more cost-effective, making this conjugate particularly attractive for low- and middle-income countries, where this pathogen has a huge burden.

Generalized Modules for Membrane Antigens as Carrier for Polysaccharides: Impact of Sugar Length, Density, and Attachment Site on the Immune Response Elicited in Animal Models

Nanoparticle systems are being explored for the display of carbohydrate antigens, characterized by multimeric presentation of glycan epitopes and special chemico-physical properties of nano-sized particles. Among them, outer membrane vesicles (OMVs) are receiving great attention, combining antigen presentation with the immunopotentiator effect of the Toll-like receptor agonists naturally present on these systems. In this context, we are testing Generalized Modules for Membrane Antigens (GMMA), OMVs naturally released from Gram-negative bacteria mutated to increase blebbing, as carrier for polysaccharides. Here, we investigated the impact of saccharide length, density, and attachment site on the immune response elicited by GMMA in animal models, using a variety of structurally diverse polysaccharides from different pathogens (i.e., Neisseria meningitidis serogroup A and C, Haemophilus influenzae type b, and streptococcus Group A Carbohydrate and Salmonella Typhi Vi). Anti-polysaccharide immune response was not affected by the number of saccharides per GMMA particle. However, lower saccharide loading can better preserve the immunogenicity of GMMA as antigen. In contrast, saccharide length needs to be optimized for each specific antigen. Interestingly, GMMA conjugates induced strong functional immune response even when the polysaccharides were linked to sugars on GMMA. We also verified that GMMA conjugates elicit a T-dependent humoral immune response to polysaccharides that is strictly dependent on the nature of the polysaccharide. The results obtained are important to design novel glycoconjugate vaccines using GMMA as carrier and support the development of multicomponent glycoconjugate vaccines where GMMA can play the dual role of carrier and antigen. In addition, this work provides significant insights into the mechanism of action of glycoconjugates.

Novel Simple Conjugation Chemistries for Decoration of GMMA with Heterologous Antigens

Outer Membrane Vesicles (OMV) constitute a promising platform for the development of efficient vaccines. OMV can be decorated with heterologous antigens (proteins or polysaccharides), becoming attractive novel carriers for the development of multicomponent vaccines. Chemical conjugation represents a tool for linking antigens, also from phylogenetically distant pathogens, to OMV. Here we develop two simple and widely applicable conjugation chemistries targeting proteins or lipopolysaccharides on the surface of Generalized Modules for Membrane Antigens (GMMA), OMV spontaneously released from Gram-negative bacteria mutated to increase vesicle yield and reduce potential reactogenicity. A Design of Experiment approach was used to identify optimal conditions for GMMA activation before conjugation, resulting in consistent processes and ensuring conjugation efficiency. Conjugates produced by both chemistries induced strong humoral response against the heterologous antigen and GMMA. Additionally, the use of the two orthogonal chemistries allowed to control the linkage of two different antigens on the same GMMA particle. This work supports the further advancement of this novel platform with great potential for the design of effective vaccines.

Debridement, antibiotics and implant retention (DAIR): An effective treatment option for early prosthetic joint infections

INTRODUCTION

Debridement, antibiotics and implant retention (DAIR) is an attractive treatment option for prosthetic joint infections (PJIs). However, reported success rates and predictors of DAIR failure vary widely. The primary aim of this study is to report the outcome of DAIR in patients with hip and knee PJIs receiving short course of antibiotic therapy. The secondary aim is to identify risk factors for DAIR failure.

METHODS

We performed a retrospective analysis of prospectively collected data of all hip and knee PJIs consecutively diagnosed at Quadrante Orthopedic Center, an Italian orthopedic hospital highly specialized in prosthetic surgery, from January 1, 2013 to January 1, 2019, and we analyzed those treated with DAIR.

RESULTS

Forty-seven PJIs occurred after 5102 arthroplasty procedures. Twenty-one patients (45%) aged 71 years were treated with DAIR for hip (62%) and knee (38%) PJIs. These were classified as early PJIs in 76% cases, delayed in 19% and late in 5%. Median time from PJI-related symptoms onset to implant revision surgery was 12 days (IQR, 7-20 days). The median duration of antibiotic treatment after surgery was 63 days (IQR, 53-84 days). Sixteen (76%) patients were cured after a median follow-up of 2197 days (IQR, 815-2342 days), while 5 (24%) experienced failure. At multivariate analysis, delayed/late PJIs were significantly associated with failure (OR = 12.51; 95% CI 1.21-129.63, p = 0.03).

CONCLUSIONS

DAIR represents an effective strategy for the treatment of early PJIs in spite of short course of antibiotic therapy.

Gold nanoparticles morphology does not affect the multivalent presentation and antibody recognition of Group A Streptococcus synthetic oligorhamnans

The development of novel delivery systems capable of enhancing the antibody binding affinity and immunoactivity of short length saccharide antigens is at the forefront of modern medicine. In this regard, gold nanoparticles (AuNPs) raised great interest as promising nano-vaccine platform, as they do not interfere with the desired immune response and their surface can be easily functionalized, enabling the antigen multivalent presentation. In addition, the nanoparticles morphology can have a great impact on their biological properties. Gram-positive Group A Streptococcus (GAS) is a bacterium responsible for many infections and represents a priority healthcare concern, but a universal vaccine is still unavailable. Since all the GAS strains have a cell wall characterized by a common polyrhamnose backbone, this can be employed as alternative antigen to develop an anti-GAS vaccine. Herein, we present the synthesis of two oligorhamnoside fragments and their corresponding oligorhamnoside-AuNPs, designed with two different morphologies. By competitive ELISA we assessed that both symmetric and anisotropic oligorhamnan nanoparticles inhibit the binding of specific polyclonal serum much better than the unconjugated oligosaccharides.

GMMA and Glycoconjugate Approaches Compared in Mice for the Development of a Vaccine against Shigella flexneri Serotype 6

Shigella infections are one of the top causes of diarrhea throughout the world, with Shigella flexneri being predominant in developing countries. Currently, no vaccines are widely available and increasing levels of multidrug-resistance make Shigella a high priority for vaccine development. The serotype-specific O-antigen moiety of Shigella lipopolysaccharide has been recognized as a key target for protective immunity, and many O-antigen based candidate vaccines are in development. Recently, the Generalized Modules for Membrane Antigens (GMMA) technology has been proposed as an alternative approach to traditional glycoconjugate vaccines for O-antigen delivery. Here, these two technologies are compared for a vaccine against S. flexneri serotype 6. Genetic strategies for GMMA production, conjugation approaches for linkage of the O-antigen to CRM₁₉₇ carrier protein, and a large panel of analytical methods for full vaccine characterization have been put in place. In a head-to-head immunogenicity study in mice, GMMA induced higher anti-O-antigen IgG than glycoconjugate administered without Alhydrogel. When formulated on Alhydrogel, GMMA and glycoconjugate elicited similar levels of persistent anti-O-antigen IgG with bactericidal activity. Glycoconjugates are a well-established bacterial vaccine approach, but can be costly, particularly when multicomponent preparations are required. With similar immunogenicity and a simpler manufacturing process, GMMA are a promising strategy for the development of a vaccine against Shigella.

Development of FAcE (Formulated Alhydrogel competitive ELISA) method for direct quantification of OAg present in Shigella sonnei GMMA-based vaccine and its optimization using Design of Experiments approach

Many formulated vaccines, including 1790GAHB Shigella sonnei GMMA-based vaccine, contain Alhydrogel (aluminum hydroxide), consequently the antigen content must be determined in the formulated final vaccine product, as required by regulatory authorities. The direct quantification of antigens adsorbed on aluminum salts is difficult, and antigens may need to be extracted using laborious and often ineffective desorption procedures. To directly quantify the sugar vaccine target in the LPS of 1790GAHB, we have developed a new FAcE (Formulated Alhydrogel competitive ELISA) method. FAcE is an immunoassay based on the competition between S. sonnei LPS, coated on the ELISA plate, and the LPS in formulated S. sonnei GMMA, in binding a specific monoclonal antibody. To optimize the method, which is as easy to perform as a standard ELISA, we have applied a Design of Experiments (DOE) approach. A model was found to define the significant assay variables and to predict their impact on the output responses. Results obtained using the DOE optimized FAcE assay showed that the method is sensitive (0.02 μg/mL lower detection limit), precise, reproducible and can accurately quantify independently formulated drug products, making it a useful tool in routine tests of Alhydrogel-based vaccines. We are currently using this method to determine S. sonnei vaccine potency, stability and lot-to-lot variations, and are broadening its applicability to quantify active ingredients of other Alhydrogel GMMA-vaccines and in multivalent vaccines formulations.

Bone turnover biomarkers identify unique prognostic risk groups in men with castration resistant prostate cancer and skeletal metastases: Results from SWOG S0421

BACKGROUND

Skeletal metastases often occur in men with castration-resistant prostate cancer (CRPC) where bone biomarkers are prognostic for overall survival (OS). In those with highly elevated markers, there is preferential benefit from bone-targeted therapy. In the phase IIIS0421 docetaxel +/- atrasentan trial, clinical covariates and bone biomarkers were analyzed to identify CRPC subsets with differential outcomes.

SUBJECTS AND METHODS

Markers of bone resorption [N-telopeptide-NTx; pyridinoline-PYD] and formation [C-terminal collagen propeptide-CICP; bone alkaline phosphatase-BAP] were measured in pre-treatment sera. Bone biomarkers and clinical covariates were included in a Cox model for OS; bone markers were added in a stepwise selection process. Receiver operating characteristic (ROC) curves were constructed for risk factor models +/- bone markers. Significant variables were allowed to compete in a classification and regression tree (CART) analysis. Hazard ratios(HR) were calculated by comparing OS in each of the terminal nodes to a reference group in a Cox model.

RESULTS

750 patients were included. Each bone marker significantly contributed to the risk factor-adjusted OS Cox model, with higher levels associated with worse OS. BAP (HR = 1.15, p = 0.008), CICP (HR = 1.27, p < 0.001), and PYD (HR = 1.21, p = 0.047) in combination were significantly associated with OS. Prognostic accuracy was improved by addition of bone markers to clinical covariates. CART analysis selected CICP, BAP, hemoglobin, and pain score for the final OS model, identifying five prognostic groups.

CONCLUSIONS

Elevated serum bone biomarker levels are associated with worse OS in bone-metastatic CRPC. Bone biomarkers can identify unique prognostic subgroups. These results further define the role of bone biomarkers in the design of CRPC trials.

Mipsagargin, a novel thapsigargin-based PSMA-activated prodrug: results of a first-in-man phase I clinical trial in patients with refractory, advanced or metastatic solid tumours

Background:

Mipsagargin (G-202; (8-O-(12-aminododecanoyl)-8-O-debutanoyl thapsigargin)-Asp-γ-Glu-γ-Glu-γ-GluGluOH)) is a novel thapsigargin-based targeted prodrug that is activated by PSMA-mediated cleavage of an inert masking peptide. The active moiety is an inhibitor of the sarcoplasmic/endoplasmic reticulum calcium adenosine triphosphatase (SERCA) pump protein that is necessary for cellular viability. We evaluated the safety of mipsagargin in patients with advanced solid tumours and established a recommended phase II dosing (RP2D) regimen.

Methods:

Patients with advanced solid tumours received mipsagargin by intravenous infusion on days 1, 2 and 3 of 28-day cycles and were allowed to continue participation in the absence of disease progression or unacceptable toxicity. The dosing began at 1.2 mg m⁻² and was escalated using a modified Fibonacci schema to determine maximally tolerated dose (MTD) with an expansion cohort at the RP2D. Plasma was analysed for mipsagargin pharmacokinetics and response was assessed using RECIST criteria.

Results:

A total of 44 patients were treated at doses ranging from 1.2 to 88 mg m⁻², including 28 patients in the dose escalation phase and 16 patients in an expansion cohort. One dose-limiting toxicity (DLT; Grade 3 rash) was observed in the dose escalation portion of the study. At 88 mg m⁻², observations of Grade 2 infusion-related reaction (IRR, 2 patients) and Grade 2 creatinine elevation (1 patient) led to declaration of 66.8 mg m⁻² as the recommended phase II dose (RP2D). Across the study, the most common treatment-related adverse events (AEs) were fatigue, rash, nausea, pyrexia and IRR. Two patients developed treatment-related Grade 3 acute renal failure that was reversible during the treatment-free portion of the cycle. To help ameliorate the IRR and creatinine elevations, a RP2D of 40 mg m⁻² on day 1 and 66.8 mg m⁻² on days 2 and 3 with prophylactic premedications and hydration on each day of infusion was established. Clinical response was not observed, but prolonged disease stabilisation was observed in a subset of patients.

Conclusions:

Mipsagargin demonstrated an acceptable tolerability and favourable pharmacokinetic profile in patients with solid tumours.

The SH2 domain interaction landscape

Members of the SH2 domain family modulate signal transduction by binding to short peptides containing phosphorylated tyrosines. Each domain displays a distinct preference for the sequence context of the phosphorylated residue. We have developed a high-density peptide chip technology that allows for probing of the affinity of most SH2 domains for a large fraction of the entire complement of tyrosine phosphopeptides in the human proteome. Using this technique, we have experimentally identified thousands of putative SH2-peptide interactions for more than 70 different SH2 domains. By integrating this rich data set with orthogonal context-specific information, we have assembled an SH2-mediated probabilistic interaction network, which we make available as a community resource in the PepspotDB database. A predicted dynamic interaction between the SH2 domains of the tyrosine phosphatase SHP2 and the phosphorylated tyrosine in the extracellular signal-regulated kinase activation loop was validated by experiments in living cells.

The protein interaction network mediated by human SH3 domains

Families of conserved protein domains, specialized in mediating interactions with short linear peptide motifs, are responsible for the formation of a variety of dynamic complexes in the cell. An important subclass of these motifs are characterized by a high proline content and play a pivotal role in biological processes requiring the coordinated assembly of multi-protein complexes. This is achieved via interaction of proteins containing modules such as Src Homology-3 (SH3) or WW domains and specific proline rich patterns. Here we make available via a publicly accessible database a synopsis of our current understanding of the interaction landscape of the human SH3 protein family. This is achieved by integrating an information extraction strategy with a new experimental approach. In a first approach we have used a text mining strategy to capture a large number of manuscripts reporting interactions between SH3 domains and target peptides. Relevant information was annotated in the MINT database. In a second experimental approach we have used a variant of the WISE (Whole Interactome Scanning Experiment) strategy to probe a large number of naturally occurring and chemically-synthesized peptides arrayed at high density on a glass surface. By this method we have tested 60 human SH3 domains for their ability to bind a collection of 9192 poly-proline containing peptides immobilized on a glass chip. To evaluate the quality of the resulting interaction dataset, we retested some of the interactions on a smaller scale and performed a series of pull down experiments on native proteins. Peptide chips, pull down assays, SPOT synthesis and phage display experiments have allowed us to further characterize the specificity and promiscuity of proline-rich binding domains and to map their interaction network. Both the information captured from the literature and the interactions inferred from the peptide chip experiments were collected and stored in the PepspotDB (http://mint.bio.uniroma2.it/PepspotDB/).

Enriching the viral-host interactomes with interactions mediated by SH3 domains

Protein-protein interactions play an essential role in the regulation of most cellular processes. The process of viral infection is no exception and many viral pathogenic strategies involve targeting and perturbing host-protein interactions. The characterization of the host protein subnetworks disturbed by invading viruses is a major goal of viral research and may contribute to reveal fundamental biological mechanisms and to identify new therapeutic strategies. To assist in this approach, we have developed a database, VirusMINT, which stores in a structured format most of the published interactions between viral and host proteome. Although SH3 are the most ubiquitous and abundant class of protein binding modules, VirusMINT contains only a few interactions mediated by this domain class. To overcome this limitation, we have applied the whole interactome scanning experiment approach to identify interactions between 15 human SH3 domains and viral proline-rich peptides of two oncogenic viruses, human papillomavirus type 16 and human adenovirus A type 12. This approach identifies 114 new potential interactions between the human SH3 domains and proline-rich regions of the two viral proteomes.

The central proline rich region of POB1/REPS2 plays a regulatory role in epidermal growth factor receptor endocytosis by binding to 14-3-3 and SH3 domain-containing proteins

BACKGROUND

The human POB1/REPS2 (Partner of RalBP1) protein is highly conserved in mammals where it has been suggested to function as a molecular scaffold recruiting proteins involved in vesicular traffic and linking them to the actin cytoskeleton remodeling machinery. More recently POB1/REPS2 was found highly expressed in androgen-dependent prostate cancer cell lines, while one of its isoforms (isoform 2) is down regulated during prostate cancer progression.

RESULTS

In this report we characterize the central proline rich domain of POB1/REPS2 and we describe for the first time its functional role in receptor endocytosis. We show that the ectopic expression of this domain has a dominant negative effect on the endocytosis of activated epidermal growth factor receptor (EGFR) while leaving transferrin receptor endocytosis unaffected. By a combination of different approaches (phage display, bioinformatics predictions, peptide arrays, mutagenic analysis, in vivo co-immunoprecipitation), we have identified two closely spaced binding motifs for 14-3-3 and for the SH3 of the proteins Amphiphysin II and Grb2. Differently from wild type, proline rich domains that are altered in these motifs do not inhibit EGFR endocytosis, suggesting that these binding motifs play a functional role in this process.

CONCLUSION

Our findings are relevant to the characterization of the molecular mechanism underlying the involvement of POB1/REPS2, SH3 and 14-3-3 proteins in receptor endocytosis, suggesting that 14-3-3 could work by bridging the EGF receptor and the scaffold protein POB1/REPS2.

Results of a phase III randomized controlled trial of the safety and efficacy of atrasentan in men with nonmetastatic hormone-refractory prostate cancer (HRPC)

5018

Introduction: Atrasentan is a potent oral, selective endothelin A receptor antagonist with biological activity in patients with HRPC. This randomized phase III trial of atrasentan vs placebo was conducted in 941 men with nonmetastatic HRPC whose prostate-specific antigen (PSA) was rising despite adequate androgen suppression. Methods: 467 patients were randomized to receive atrasentan 10 mg and 474 patients were randomized to receive placebo daily. Primary efficacy endpoints were time to disease progression (TTP) and progression-free survival, with progression defined as the onset of metastases. Secondary endpoints were overall survival, time to PSA progression, change from baseline in bone alkaline phosphatase (BAP), and PSA doubling time (PSADT). Results: In the intent-to-treat population, median TTP was 764 days with atrasentan and 671 days with placebo (hazard ratio [HR], 0.915; G1,1 P=0.288). More placebo- treated patients (267, 56.3%) than atrasentan-treated patients (227, 48.6%) experienced disease progression. Overall, 278 patients (29.5%) discontinued before reaching a protocol-defined endpoint (155, 40.8% US vs 123, 21.6% non-US). More placebo-treated patients (210, 44.3%) than atrasentan-treated patients (169, 36.2%) experienced new skeletal lesions. Median survival was 1,477 days for the atrasentan group and 1,403 days for the placebo group (HR, 0.909; G1,1 P=0.176). Mean change from baseline to final BAP was -1.51 IU/L with atrasentan compared with +2.20 IU/L with placebo (P<0.001). PSADT was lengthened with atrasentan relative to placebo (P<0.031). The incidence of peripheral edema, nasal congestion, headache, dyspnea, anemia, and heart failure was significantly greater in the atrasentan group (P<0.05). Most of these events were mild and nonserious and did not result in study discontinuation. Conclusions: Data from this study did not show a statistically significant difference in time to progression between atrasentan and placebo. However, the high discontinuation rate, especially among US patients, may have compromised the ability of the study to accurately determine the treatment effect of atrasentan in this population.

No significant financial relationships to disclose.

Phase II ECOG trial of atrasentan in advanced renal cell carcinoma

5102

Background: Atrasentan, an oral selective endothelin A receptor antagonist, demonstrated activity in patients with RCC included in Phase I studies. Based on these preliminary findings, a phase II study was undertaken in patients with measurable or nonmeasurable (bone only) metastatic RCC. Methods: Patients with locally recurrent or metastatic disease were stratified on disease status (measurable or bone only metastases) and prior immunotherapy. Eligible patients also had no prior chemotherapy, no more than 1 prior immunotherapy, and ECOG PS 0, 1, or 2. Prior nephrectomy was permitted. Patients received atrasentan 10 mg/day po until progression or unacceptable toxicity. Standard RECIST criteria were used to assess response. The primary endpoint was the progression-free rate at 6 months. Rates of 25% among patients treated with prior immunotherapy and 45% among patients with no prior immunotherapy were considered promising. A two-stage design was used for cohorts with no prior immunotherapy. Results: Between July 2003 and July 2005, 98 patients were registered. Four patients were ineligible and 1 withdrew before treatment. Median duration of treatment was 10 weeks (range, 2 to 107 weeks). Toxicities were mild, with 73% of patients reporting no Grade 3 or higher treatment- related adverse events. Grade 4 adverse events included neutropenia (n=3), dyspnea (n=2), thrombosis and supraventricular arrhythmia (n=1 each). Six-month progression-free rates (90% CI) were 14% (6 - 25%), 0% (0 - 39%), 12% (3 - 28%) and 17% (5 - 38%) respectively for patients with prior immunotherapy and measurable disease (n=44), prior immunotherapy and bone metastases only (n=6), no prior immunotherapy and measurable disease (n=25), and no prior immunotherapy and bone metastases only (n=18). Median progression-free survival was 2.3 months (95% CI, 2.0 - 3.5 months). Conclusions: While well-tolerated, atrasentan did not yield 6-month progression-free rates that would support its use as first-line monotherapy in patients with advanced RCC.

No significant financial relationships to disclose.

Vascular endothelial growth factor gene polymorphisms increase the risk to develop psoriasis

We investigated the relationship between eight polymorphisms in the gene encoding for vascular endothelial growth factor (VEGF) (-1540C > A, -1512Ins18, -1451C > T, -460T > C, -160C > T, -152G > A, -116G > A and +405G > C) and plaque-type psoriasis stratified for age at onset, gender and family history of dermatosis. For this purpose, 117 patients with chronic plaque-type psoriasis and 215 healthy subjects were enrolled. We found that being homozygous -1540AA, -1512InsIns, -1451TT, -460CC and -152AA conferred a significant risk in developing psoriasis compared with heterozygous (-1540CA, -1512 + Ins, -1451CT, -460CT and -152AG) and homozygous genotypes (-1540CC, -1512 + +-1451CC, -460TT and -152GG) grouped together [odds ratio (ORs) = 1.73, 1.73, 1.73, 1.77 and 1.87, respectively]. Conversely, having the -116AA or +405GG genotype did not significantly increase the risk of disease expression compared with other genotypes of the same loci. Interestingly, we found that -1540AA, -1512InsIns, -1451TT, -460CC and -152AA homozygous genotypes have a significant two-fold increased risk in developing psoriasis after the age of 40 years (late-onset psoriasis) (ORs = 2.19, 2.19, 2.19, 2.05 and 2.26; P = 0.02, 0.02, 0.02, 0.04 and 0.02, respectively) as compared with controls. On the contrary, we found no phenotype-genotype association of the same magnitude among the patients in whom psoriasis developed at or before the age of 40 years (early-onset psoriasis) compared with controls. Genotype distributions were not significantly different when cases and controls were stratified either by gender or family history of psoriasis. Finally, VEGF plasma concentration was not significantly different between patients and controls and was not correlated with the severity of the disease.

A prospective pharmacogenomic (PG), pharmacodynamic (PD), and pharmacokinetic (PK) study of determinants of erlotinib toxicity

3080

Background: A strong but unexplained association between skin toxicity (rash) and survival from erlotinib therapy has been noted for patients with several epithelial malignancies. The correlation between rash and clinical benefit appears to extend across classes of epidermal growth factor receptor (EGFR)-targeted agents. Several hypothetical explanations for this association have been suggested including polymorphisms of the EGFR locus as well as PD and PK variability. Methods: We conducted this 80-subject prospective study in patients with lung (N=43), head and neck (N=9), and ovarian cancer (N=28) given erlotinib 150 mg daily to evaluate several of these hypotheses. Patients underwent toxicity monitoring, response assessment, skin biopsies pretreatment and after 28 days for immunohistochemical (IHC) analysis, as well as blood collection for PK analysis and evaluation of EGFR genetic polymorphisms reported to influence EGFR expression level. Results: 72/80 subjects are evaluable for toxicity. Response correlates with both worst grade diarrhea (p=0.003) and rash (p=0.044). Initial PK analysis suggests a positive association between d15 erlotinib trough level and both diarrhea (p=0.091) and rash (p=0.076). Controlling for d15 erlotinib level, EGFR intron 1 CA repeat length is also associated with rash (p=0.030). Polymorphisms in the EGFR promoter (216 G/T and 191 C/A) correlated with diarrhea (p=0.053 and 0.005 respectively) but not rash. IHC analyses including EGFR, p-EGFR, Akt, p-Akt, ERK, and p-ERK have been completed on 35 paired, pre-post treatment skin biopsies and demonstrate no strong correlations with toxicity. Conclusions: These data suggest that both interindividual PK variability and EGFR polymorphisms may contribute to erlotinib toxicity. Erlotinib effects on EGFR signaling in skin do not appear to correlate with toxicity. Samples obtained in this study are available for analysis of other candidate PG determinants of both toxicity and PK variability.

[Table: see text]

A phase II study of a weekly schedule of BMS-247550 for patients with hormone-refractory prostate cancer: A trial of the Eastern Cooperative Oncology Group (E3803)

4618

Background: BMS-247550 (ixabepilone) is an epothilone B analogue with activity in taxane-resistent cancer cell lines. Ixabepilone has been administered using a q3wks schedule with significant neutropenia observed. Here we assess the activity and toxicity of ixabepilone, administered using a weekly schedule, in men with metastatic hormone-refractory prostate cancer. Methods: Patients with metastatic hormone-refractory prostate cancer (chemonaive and prior taxane) were treated with ixabepilone at 20 mg/m2 IV weekly × 3, in 4 wk cycles. This non-comparative study had a planned accrual of 29 chemonaive and 27 prior-taxane treated patients in order to detect a 50% PSA reduction using Consensus Criteria in at least 50% (91% power, α = 0.10) chemonaive and 30% (power 90%, α = 0.10) prior-taxane treated patients. Results: 32 pts with chemonaive and 37 pts with prior-taxane have been enrolled on this study. Median follow-up is 1.8 and 4.1 months respectively. Safety data is reported for the first 56 subjects (24 chemonaive and 32 prior taxane). Hematologic toxicity: Grade 3/4 neutropenia was seen in 10 pts (5 chemonaive, 5 prior-taxane). No significant thrombocytopenia was observed. Grade 3/4 neuropathy was seen in 7 pts (2 chemonaive, 5 prior-taxane). Grade 3 fatigue noted in 8 (3 chemonaive, 5 prior-taxane), grade 3 diarrhea in 5 (4 chemonaive, 1 prior-taxane), and grade 3 nausea in 3 subjects. Lastly, 2 subjects were reported to have developed a grade 3 ileus during therapy. Conclusions: In 56 subjects, BMS-247550 was found to have an acceptable toxicity profile when administered using a weekly schedule. Myelosuppression appeared to be improved, as compared to historical data with the q3wk schedule, using this dose and schedule. PSA/objective responses have been seen but at this time, no conclusion regarding its activity in the first or second-line setting can be made, as the response assessment is ongoing. Complete toxicity and response data will be presented for the entire group.

No significant financial relationships to disclose.

A phase 3, randomized, 3-arm study of temsirolimus (TEMSR) or interferon-alpha (IFN) or the combination of TEMSR + IFN in the treatment of first-line, poor-risk patients with advanced renal cell carcinoma (adv RCC)

LBA4

Background: Temsirolimus (TEMSR, CCI-779) is a specific inhibitor of mTOR, a signaling protein that regulates cell growth and angiogenesis. In a single-agent, phase 2 study, TEMSR administration to heavily pretreated patients (pts, n = 111) with adv RCC resulted in a median overall survival (OS) of 15.0 mos (Atkins et al, J Clin Oncol 2004). Retrospectively, 49 pts were categorized in a poor-risk group (Motzer et al, J Clin Oncol 2002). The TEMSR-treated pts in this group had a 1.7-fold longer median OS than the first-line, IFN-treated, poor-risk group reported by Motzer et al. In a phase 1 study, the maximum tolerated dose of the combination of TEMSR + IFN in adv RCC pts was TEMSR 15 mg intravenously (IV) once/wk + IFN 6 million units (MU) subcutaneously (SC) 3 times weekly (TIW) (Smith et al, Proc ASCO 2004). Thus, this phase 3 study in first-line, poor-risk adv RCC pts was initiated in July 2003. Methods: Pts with adv RCC and no prior systemic therapy were enrolled in this open-label study if they had ≥3 of 6 risk factors (the 5 Motzer criteria and >1 metastatic disease site). Pts were randomized (1:1:1) to arm 1, IFN up to 18 MU SC TIW; arm 2, TEMSR 25 mg IV once/wk; or arm 3, TEMSR 15 mg IV once/wk + IFN 6 MU SC TIW. The primary study endpoint was OS; the study was powered to compare the TEMSR arms with the IFN arm. Results: We report 20 Mar 2006 preliminary data from an interim analysis performed by the IDMC. Of the 626 pts enrolled, 442 deaths occurred. Patients treated with TEMSR had a statistically longer survival than those treated with IFN (Table). OS of patients treated with IFN and TEMSR + IFN were not statistically different. The 3 most frequently occurring adverse events ≥gr 3 were asthenia (arm 1: arm 2: arm 3, 27%: 12%: 30% pts), anemia (24%: 21%: 39% pts), and dyspnea (8%: 9%: 11% pts). Conclusions: Single-agent TEMSR significantly increases the OS of first-line, poor-risk adv RCC pts compared with IFN, with an acceptable safety profile.

[Table: see text] [Table: see text]

Phase 1 pharmacokinetic and pharmacodynamic study of the histone deacetylase inhibitor MS-275 in combination with 13-cis retinoic acid in patients with advanced solid tumors

3055

Background: Preclinical studies suggest that histone deacetylase (HDAC) inhibitors may restore tumor sensitivity to retinoids. The objective of this study was to determine the maximum-tolerated dose (MTD), the dose-limiting toxicity (DLT), and the pharmacokinetic (PK)/pharmacodynamic (PD) profiles of the HDAC inhibitor MS-275 in combination with 13-cis retinoic acid (CRA). Methods: Patients (pts) with advanced solid tumors were treated with MS-275 orally once weekly and CRA orally twice daily x 3 weeks every 4 weeks. The starting dose for MS-275 was 4 mg/m2 and the dose was escalated based on toxicity assessments. The fixed dose for CRA was 1 mg/kg/day. PK concentrations of MS-275 and CRA were determined by LC/MS/MS. Western Blot analysis on peripheral-blood mononuclear cells (PBMCs) and tumor samples (when feasible) were performed to evaluate target inhibition. Results: To date thirteen pts have been enrolled. Tumor types include prostate (4 pts), bladder and renal cell (2 pts), and others. The MTD was exceeded at the 5 mg/m2 dose level (G3 hyponatremia, neutropenia and anemia). Fatigue (G1 or G2) is a common side effect. MS-275 peak concentrations were 141.6±75.7ng/mL at 4mg/m2 and 139.5±30.9 ng/mL at 5mg/m2. MS-275 half-life and clearance were 108.2±47.9h and 9.4±6.0L/h/m2, which is consistent with prior reports for MS-275 as single agent. Median CRA steady-state trough levels were 182.4 ng/mL. The MTD was 4 mg/m2 MS-275 and 1 mg/kg CRA. Five pts remained on treatment for ≥ 4 months including pts with prostate cancer (3), pancreatic cancer (6 months) and a pt with renal cell carcinoma (12 months) who presented a partial response in the lungs. Histones isolated from PBMCs showed transient but consistent protein acetylation post-therapy. Tumor biopsy of a liver lesion from prostate carcinoma revealed post-therapy induced histone acetylation and decreased phosphorylated ERK and STAT3 protein expression consistent with HDAC inhibitory activity. Conclusions: Combination of MS-275 with CRA is reasonably well tolerated and 4 mg/m2 is the Phase II recommended dose for MS-275 in combination with CRA. Tumor response and PD data suggest clinical and biological activity for this combination strategy.

[Table: see text]

Phase I study of isotype-selective histone deacetylase (HDAC) inhibitor MGCD0103 given as three-times weekly oral dose in patients (pts) with advanced solid tumors

3007

Background: MGCD0103 is a novel isotype-selective inhibitor of human HDACs. Deacetylation of histones by HDACs is postulated to inactivate tumor suppressor genes leading to neoplastic transformation. Inhibition of these enzymes might restore normal growth control. Methods: A phase I trial of MGCD0103, given as a three-times weekly oral dose 2 out of every 3 weeks, has been performed in pts with advanced solid tumors. Main endpoints are safety, tolerability, pharmacokinetics (PK), pharmacodynamic (PD) assessments of HDAC activity and histone acetylation status in buffy coat white cells. Results: Five dose levels have been evaluated (mg/m2): 12.5, 20, 27, 36, and 45. As of January, 2006, 28 pts have been enrolled with the following demographics: M:F = 18:10; median age (range) = 60 (29–75); ECOG 0:1:2 = 9:13:1 (n = 23); primary tumor sites: colorectal (8), renal (5), lung (4), others (11); prior chemotherapy, radiotherapy, immunotherapy were given to 22, 12 and 2 pts, respectively (n=23). A total of 62 cycles have been administered, with median = 2 and range=1–7 cycles. MGCD0103 has been well tolerated; most common AEs (23 pts): grade 1–3 fatigue (91% of pts), grade 1–2 nausea and vomiting (70 and 48%), anorexia (26%), constipation (39%). Disease stabilization > 2 cycles has been observed in 3 renal cell cancer pts (4, 6, and 7 cycles) and 1 colorectal cancer pt (4 cycles). Preliminary PK analyses demonstrated intra-pt PK variability, however co-administration of acidic carbonated beverage (protocol amendment) appears to reduce variability without altering average Cmax or AUC (0–24) comparing Day 1 with Day 14. There was little accumulation or decrease in concentrations with extended dosing, and t1/2 was dose-independent at 7.7–11.3 hr. (±0.6–1.6). PD data reveal dose-dependent maximal inhibition of HDAC activity in patients co-administered an acidic beverage. Conclusions: At doses evaluated MGCD0103 appears tolerated and exhibits favourable PK and PD.

[Table: see text]

Simultaneous occurrence of linear scleroderma and homolateral segmental vitiligo

Localized scleroderma and vitiligo only rarely have been reported to occur simultaneously. Here we report a case of a 21 year old man affected with both linear scleroderma of the left upper limb and homolateral segmental vitiligo of the trunk. Since the two diseases appeared during the same period, involved the same side of the body and their progression paralleled, a possible non-coincidental association between these two diseases is discussed.

Malignant glucagonoma. New options of treatment

Few cases of malignant glucagonomas have been described in the literature. In this paper we present a case of a 77-year-old woman with necrolytic migratory erythema and high plasma glucagon and chromogranin A levels caused by a neuroendocrine tumour. An abdominal CT scan suggested a pancreatic lesion and two liver metastases. The patient underwent pancreatic debulking and liver metastasectomy. Histological and immunohistochemical investigations revealed a well differentiated neuroendocrine tumour with vascular invasion and scattered immunopositivity for somatostatin receptors. The patient was treated with octreotide (20 mg i.m. every 28 days) for three years without side effects. Three months after surgery symptoms of disease recurred accompanied by hyperglucagonaemia and newly diagnosed liver lesions. The patient was treated with octreotide (30 mg i.m. every 28 days) and interferon-alpha (6 MU s.cc 3 times per week) plus three cycles of hepatic chemoembolisation. Symptoms resolved after the first month of therapy, hormone levels decreased compared to untreated levels and metastatic growth slowed as observed by radiographic evidence. The patient is now asymptomatic with persistent hepatic disease and normal serum glucagon levels forty months after primary treatment. So far, only few immunohistochemical studies are reported on malignant glucagonoma and combined treatment schedules. We demonstrated, for the first time, a scattered immunopositivity for somatostatin receptors in a malignant glucagonoma. For this reason, the somatostatin analogs therapy was instituted. A combined antiproliferative medical treatment and the hepatic chemoembolization have been able to control tumor growth and disease symptoms for a long time after surgery.

Early but not lasting improvement of recalcitrant subcorneal pustular dermatosis (Sneddon-Wilkinson disease) after infliximab therapy: relationships with variations in cytokine levels in suction blister fluids

Subcorneal pustular dermatosis (SCPD) is an uncommon disorder, characterized by a chronic relapsing vesiculopustular eruption, mainly involving the trunk and intertriginous areas, and usually seen in women > 40 years old. Various therapies have been reported to be effective in treating SCPD, such as dapsone, systemic glucocorticoids, acitretin, etretinate, infliximab and phototherapy. We report a case of a 54-year-old woman affected by SCPD who after failure of different therapies showed a dramatic but only temporary improvement of her disease during a cycle of therapy with infliximab. In addition, an array of cytokines was simultaneously measured in suction blister fluids obtained from involved or uninvolved skin at various time intervals during the first 12 weeks of observation.

Immunohistochemical analysis of keratinocyte growth factor and fibroblast growth factor 10 expression in psoriasis

The pathogenic mechanism underlying the hyperproliferation of keratinocytes in psoriasis is still not completely clarified. The production of cytokines released by activated T lymphocytes infiltrating the upper dermis probably has a crucial role. Even dermal fibroblasts can participate in the process through the secretion of growth factors, and some studies have reported an increased expression of the insulin-like growth factor 1. Few studies, however, have focused on the possible involvement of the keratinocyte growth factor (KGF/FGF-7) and the fibroblast growth factor 10 (FGF-10/KGF-2), which are secreted by fibroblasts and stimulate keratinocyte proliferation acting through a receptor specifically expressed by epithelial cells. The aim of this study was to investigate the expression of KGF and FGF-10 on the skin of patients with psoriasis by immunohistochemical analysis and to evaluate the correlation with the lymphocyte infiltrate and the epidermal proliferation. Immunostaining for KGF and FGF-10 showed that both the growth factors are upregulated in the upper dermis of psoriatic skin, and that the expression is correlated with the presence of T-cell infiltrate and with keratinocyte proliferation. Our data suggest that in psoriatic lesions activated lymphocytes can stimulate fibroblasts to produce KGF and FGF-10, which in turn contribute to sustain the hyperproliferative status of the keratinocytes.