Survivin promotion of melanoma metastasis requires upregulation of α5 integrin.

Survivin is an apoptotic and mitotic regulator that is overexpressed in melanoma and a poor prognostic marker in patients with metastatic disease. We recently showed that Survivin enhances melanoma cell motility through Akt-dependent upregulation of α5 integrin. However, the functional role of Survivin in melanoma metastasis is not clearly understood. We found that overexpression of Survivin in LOX and YUSAC2 human melanoma cells increased colony formation in soft agar, and this effect was abrogated by knockdown of α5 integrin by RNA interference. We employed melanoma cell xenografts to determine the in vivo effect of Survivin overexpression on melanoma metastasis. Although Survivin overexpression did not affect primary tumor growth of YUSAC2 or LOX subcutaneous tumors, or indices of proliferation or apoptosis, it significantly increased expression of α5 integrin in the primary tumors and formation of metastatic colonies in the lungs. Additionally, Survivin overexpression resulted in enhanced lung colony formation following intravenous (i.v.) injection of tumor cells in vivo and increased adherence to fibronectin-coated plastic in vitro. Importantly, in vivo inhibition of α5 integrin via intraperitoneal injection of an α5ß1 integrin-blocking antibody significantly slowed tumor growth and reduced Survivin-enhanced pulmonary metastasis. Knockdown of α5 integrin in cells prior to i.v. injection also blocked Survivin-enhanced lung colony formation. These findings support a direct role for Survivin in melanoma metastasis, which requires α5 integrin and suggest that inhibitors of α5 integrin may be useful in combating this process.

Intravenous immune globulin therapy for Stevens-Johnson syndrome/toxic epidermal necrolysis complicated by hemolysis leading to pigment nephropathy and hemodialysis.

BACKGROUND: Intravenous immune globulin (IVIG) is generally thought to be of relatively low risk for adverse events and some experts consider this to be the best treatment for Stevens-Johnson syndrome/toxic epidermal necrolysis. OBJECTIVE: We evaluated the underlying cause of anemia and renal failure in 2 consecutive patients being treated with IVIG for Stevens-Johnson syndrome/toxic epidermal necrolysis. METHODS: This is a retrospective chart review. RESULTS: We present 2 patients with Stevens-Johnson syndrome/toxic epidermal necrolysis and severe hemolysis requiring blood transfusion who subsequently developed pigment nephropathy necessitating hemodialysis after treatment with IVIG. Both patients had antibodies to their ABO blood type detected in the eluate from their red blood cell membrane. LIMITATIONS: This is a retrospective review with only 2 cases. CONCLUSIONS: We propose that IVIG-associated hemolysis is an adverse reaction that may not be as rare as once thought, presenting as a mild decrease in hemoglobin and hematocrit. Antibodies to blood type A and B are given as part of pooled immune globulin and are considered to be the cause of hemolysis. More severe anemia requiring transfusion is less common, and the breakdown products produced by hemolysis can lead to pigment nephropathy and renal failure. We present methods by which this severe complication can be anticipated and managed more effectively.

Radiographic and micro-computed tomographic imaging of lipopolysaccharide-mediated bone resorption.

OBJECTIVES: Chronic otitis media and cholesteatomas cause hearing loss as a result of bony erosion. This bone resorption is known to be more aggressive when cholesteatomas become infected. The most common organism isolated from both diseases is the gram-negative bacterium Pseudomonas aeruginosa. Lipopolysaccharide (LPS), a major virulence factor found in the gram-negative bacterial cell wall, is well known to incite inflammatory bone resorption. The mechanisms underlying this process, however, are poorly understood. In this study, we developed a mouse model of calvarial osteolysis in which resorption was reliably imaged by plain radiography and micro-computed tomography (micro-CT). METHODS: A murine calvarial model was developed to study bone resorption induced by P aeruginosa LPS. Calvariae from wild-type and knockout mice used in this model were imaged by plain radiography and micro-CT. RESULTS: A high degree of correlation between plain radiography and micro-CT was identified (R2 = 0.8554). Furthermore, maximal LPS-induced bone resorption required functioning toll-like receptor (TLR) 2, TLR4, and myeloid differentiation factor 88 (MyD88). CONCLUSIONS: We have developed a successful model of inflammatory osteolysis in which plain radiography can reliably delineate induced bone resorption. In vivo, we have shown that P aeruginosa LPS signals via TLR2, as well as TLR4 through MyD88.

Human breast tumor-infiltrating CD8+ T cells retain polyfunctionality despite PD-1 expression.

Functional CD8+ T cells in human tumors play a clear role in clinical prognosis and response to immunotherapeutic interventions. PD-1 expression in T cells involved in chronic infections and tumors such as melanoma often correlates with a state of T-cell exhaustion. Here we interrogate CD8+ tumor-infiltrating lymphocytes (TILs) from human breast and melanoma tumors to explore their functional state. Despite expression of exhaustion hallmarks, such as PD-1 expression, human breast tumor CD8+ TILs retain robust capacity for production of effector cytokines and degranulation capacity. In contrast, melanoma CD8+ TILs display dramatic reduction of cytokine production and degranulation capacity. We show that CD8+ TILs from human breast tumors can potently kill cancer cells via bi-specific antibodies. Our data demonstrate that CD8+ TILs in human breast tumors retain polyfunctionality, despite PD-1 expression, and suggest that they may be harnessed for effective immunotherapies.

Pseudomonas aeruginosa lipopolysaccharide induces osteoclastogenesis through a toll-like receptor 4 mediated pathway in vitro and in vivo.

OBJECTIVES: Bacterial infections near bone result in localized inflammatory osteolysis, a significant complication of chronic ear infections. While many bacterial products may be involved, lipopolysaccharide (LPS) has been implicated as a major mediator of inflammation and osteolysis. However, the mechanisms by which LPS promotes bone resorption have not been clearly established. There is no consensus on whether LPS acts directly or indirectly on osteoclast precursors (bone marrow monocytes [BMM]) to induce bone resorption. In light of the role of Pseudomonas aeruginosa, in chronic ear infections, we investigated the effects of P. aeruginosa LPS on osteoclastogenesis in vivo and in vitro. METHODS: Wild-type C57BL/6J and toll-like receptor 4 knock-out (TLR4-/-) mice received subcutaneous calvarial injections of 250 mug of P. aeruginosa LPS or phosphate buffered saline (PBS) only (n = 5 per group). Osteoclastic bone resorption was assessed histologically. The effect of P. aeruginosa LPS on bone resorption was assessed in vitro using combinations of BMMs and osteoblasts with and without functional toll-like receptor 4 (TLR4). RESULTS: In vivo, P. aeruginosa LPS induced robust osteolysis, and this effect was completely abrogated in mice lacking expression of TLR4. In vitro, P. aeruginosa LPS failed to induce development of osteoclasts directly in BMMs. However, P. aeruginosa LPS did stimulate osteoclastogenesis in BMM-osteoblast cocultures. CONCLUSIONS: P. aeruginosa LPS acts indirectly through osteoblasts to induce bone resorption. Optimal osteoclastogenesis in vitro required functional TLR4 expression in both BMMs and osteoblasts.

Otopathogenic Pseudomonas aeruginosa strains as competent biofilm formers.

OBJECTIVE: To determine whether Pseudomonas aeruginosa, a common cholesteatoma pathogen, known to form biofilms in other chronic infections, is capable of contributing to biofilm formation in cholesteatoma. DESIGN: We tested 12 OPPA isolates for several aspects of biofilm formation, including adherence to human keratinocytes, expression of quorum-sensing genes, twitching motility, and production of extracellular matrix as determined by both crystal violet staining and carbazole reaction. RESULTS: Ten OPPA strains demonstrated increased adherence (1.5- to 12-fold) to human keratinocytes relative to PAO1, a laboratory strain. Expression of las and rhl quorum-sensing products were detected in 11 OPPA strains. By crystal violet staining, we found biofilm formation in all OPPA strains equal to or greater than that found in PAO1 (2- to 18-fold). In addition, OPPA strains demonstrated mucoid characteristics, including down-regulation of twitching motility and increased alginate production. CONCLUSIONS: Strains of OPPA isolated from cholesteatoma are strongly adherent to keratinocytes and capable of forming biofilm. In addition, OPPA strains have mucoid characteristics in vitro. When these bacteria assume a biofilm phenotype, they are highly resistant to antibiotics and host defenses. These data suggest that OPPA can contribute to biofilm formation in cholesteatoma, leading to the persistence of this infection.

A possible role for nitric oxide in osteoclastogenesis associated with cholesteatoma.

HYPOTHESIS: This study was designed to investigate the potential role of nitric oxide in cholesteatoma-induced bone resorption, in vitro and in vivo. BACKGROUND: Cholesteatoma is a disease of inflammatory bone resorption in the middle ear leading to hearing loss and vestibular dysfunction. Inappropriate activation of osteoclasts causes the morbidity associated with this disease. Previous studies suggest nitric oxide may be an important mediator of osteoclast function. METHODS: A murine model of cholesteatoma induced bone resorption was used to demonstrate nitric oxide synthase (NOS) gene expression and the effect of a NOS inhibitor. An in vitro osteoclast culture method was used to demonstrate the effect of nitric oxide on isolated osteoclasts. Osteoclast development was assayed by counting the number of mature osteoclasts; activity was assayed by measuring the amount of resorbed bone. RESULTS: Quantitative reverse transcriptase-polymerase chain reaction results demonstrated the temporal expression of all three NOS isoforms in vivo. NOS I demonstrated very low levels of expressions throughout the duration of the study with no change in expression in response to keratin implant. Similarly, NOS III also demonstrated low levels of expression and no change in response to keratin. NOS II was highly upregulated in response to keratin throughout the duration of the study. In vitro, pharmacological nitric oxide donors--sodium nitroprusside and S-nitroso-N-acetyl-D,L-penicillamine--dose-dependently stimulated osteoclast resorption. Alone, interferon gamma (IFNgamma)--but not IL-1beta or TNFalpha--generated nitrite in vitro. A cytokine cocktail of IL-1beta, TNFalpha, and IFNgamma synergistically enhanced nitrite production. Nitrite production was blocked by the addition of aminoguanidine (AG), suggesting that AG-inhibited cytokine mediated nitrite production. However, in an in vivo model of cholesteatoma-induced bone resorption, the osteoclast response of AG-treated mice was not statistically different from untreated controls. CONCLUSIONS: All three NOS isoforms were expressed in an in vivo model of cholesteatoma-induced bone resorption with significant upregulation of NOS II throughout the study. Exogenously administered nitric oxide dose-dependently enhanced osteoclast activation in vitro. The pro-inflammatory cytokines, IL-1beta, TNFalpha, and IFNgamma, synergistically induce nitrite production, which was abrogated by treatment with the nitric oxide synthase inhibitor, AG. Although AG suppresses nitrite production in vitro, treatment had no effect on osteoclast response in vivo, suggesting that the effects of inflammatory cytokines on osteoclast response were mediated through other pathways.

Zoledronic acid inhibits osteoclastogenesis in vitro and in a mouse model of inflammatory osteolysis.

This study assessed effects of the bisphosphonate zoledronic acid (ZLNA) on osteoclastogenesis. To assess the effect of ZLNA on osteoclast formation in vitro, we cultured mouse bone marrow cells under conditions that promote osteoclastogenesis. Administered at concentrations from 10(-6) to 10(-9) mol/L, ZLNA led to a dose-dependent inhibition of osteoclastogenesis. Combined TUNEL staining and histochemical staining for tartrate-resistant acid phosphatase showed that ZLNA induced apoptosis in osteoclasts and monocytic precursor cells. To study the effects of ZLNA in vivo, we placed keratin particles onto the surface of the parietal bone of mice to induce localized inflammatory bone resorption. Three experimental groups received daily subcutaneous injections of ZLNA (1, 3, or 10 microg/kg body weight) from 4 days before surgery until 5 days after keratin implantation. The ZLNA significantly reduced osteoclast recruitment in a dose-dependent manner, but did not affect the degree of inflammation or the mineral apposition rate.

P. aeruginosa infection increases morbidity in experimental cholesteatomas.

OBJECTIVES: Clinicians have long noted that infected cholesteatomas are more aggressive than uninfected ones without data to support these observations. The purpose of this study is to determine the etiological role of biofilm forming P. aeruginosa (PA) and the virulence factor, type IV pili (TFP), in the pathogenesis of experimental cholesteatomas. DESIGN: We evaluated three different PA strains and one Escherichia coli strain in cholesteatoma progression: PA14, a well-characterized wound isolate, OPPA8, an otopathogenic strain from a human cholesteatoma, OPPA8-NP, an isogenic TFP deletion mutant, and DH5α, an E. coli strain. METHODS: Cholesteatomas were induced in gerbils. We inoculated the right ear with bacteria and the left with vehicle. After 6 weeks their cholesteatomas were evaluated by micro-CT scanning. Cholesteatoma size and bone resorption were analyzed digitally. RESULTS: Results demonstrate that PA infection increases cholesteatoma size when compared to uninfected controls: OPPA8 showed an 8.9-fold increase, PA14 a 2.6-fold increase, OPPA8-NP a 1.9-fold increase, while DH5α was not increased over controls. Additionally, infected bullae showed 10 to 50% more cholesteatoma-induced bone resorption. CONCLUSIONS: In this model, PA infected cholesteatomas enlarge more rapidly and are more destructive than uninfected controls. OPPA8, the strain from a human cholesteatoma, showed the greatest enlargement and bone destruction. Additionally, we demonstrate that TFP is a virulence factor in this model because the nonpiliated isogenic mutant, OPPA8-NP, was significantly less aggressive than the wild-type OPPA8 indicating that type IV pili may be a virulence factor in this disease.

Lipopolysaccharide-induced osteoclastogenesis from mononuclear precursors: a mechanism for osteolysis in chronic otitis.

Osteoclasts are the only cells capable of carrying out bone resorption and therefore are responsible for the osteolysis seen in infectious diseases such as chronic otitis media and infected cholesteatoma. Pseudomonas aeruginosa is the most common organism isolated from these infectious middle ear diseases. In this study, we examined the mechanisms by which P. aeruginosa lipopolysaccharide (LPS) stimulates osteoclastogenesis directly from mononuclear osteoclast precursor cells. Osteoclast precursors demonstrated robust, bone-resorbing osteoclast formation when stimulated by P. aeruginosa LPS only if previously primed with permissive, sub-osteoclastogenic doses of receptor activator of NF-kappaB ligand (RANKL), suggesting that LPS is osteoclastogenic only during a specific developmental window. Numerous LPS-elicited cytokines were found to be released by osteoclast precursors undergoing P. aeruginosa LPS-mediated osteoclast formation. Two lines of evidence suggest that several cytokines promote Oc formation in an autocrine/paracrine manner. First, inhibition of several cytokine pathways including TNF-alpha, IL-1, and IL-6 block the osteoclastogenesis induced by LPS. Secondly, increased expression of the receptors for TNF-alpha and IL-1 was demonstrated by real-time quantitative polymerase chain reaction. Such a mechanism has not previously been established and demonstrates the ability of osteoclast precursors to autonomously facilitate bone destruction.

Inefficient presentation of tumor-derived antigen by tumor-infiltrating dendritic cells.

BACKGROUND: Transplantable B16 melanoma is widely used as a tumor model to investigate tumor immunity. We wished to characterize the leukocyte populations infiltrating B16 melanoma tumors, and the functional properties of tumor-infiltrating dendritic cells (TIDC). MATERIALS AND METHODS: We used the B16 melanoma cell line expressing ovalbumin protein (OVA) to investigate the phenotype and T cell stimulatory capacity of TIDC. RESULTS: The majority of leukocytes in B16 melanoma were macrophages, which colocalized with TIDCs, B and T cells to the peripheral area of the tumor. Both myeloid and plasmacytoid DC populations were present within tumors. Most of these DCs appeared immature, but about a third expressed a mature phenotype. TIDCs did not present tumor-derived antigen, as they were unable to induce the proliferation of tumor-specific CD4+ and CD8+ T cells in vitro unless in the presence of specific peptides. Some presentation of tumor-derived antigen could be demonstrated in the tumor-draining lymph node using in vivo proliferation assays. However, while proliferation of CD8+ T cells was reproducibly demonstrated, no proliferation of CD4+ T cells was observed. CONCLUSION: In summary, our data suggest that DCs in tumors have limited antigen-presenting function. Inefficient antigen presentation extends to the tumor-draining lymph node, and may affect the generation of antitumor immune responses.

Gentian violet and ferric ammonium citrate disrupt Pseudomonas aeruginosa biofilms.

OBJECTIVE/HYPOTHESIS: Bacterial biofilms are resistant to antibiotics and may contribute to persistent infections including chronic otitis media and cholesteatoma. Discovery of substances to disrupt biofilms is necessary to treat these chronic infections. Gentian violet (GV) and ferric ammonium citrate (FAC) were tested against Pseudomonas aeruginosa biofilms to determine if either substance can reduce biofilm volume. STUDY DESIGN: The biofilm volume and planktonic growth of PAO1 and otopathogenic P. aeruginosa (OPPA8) isolated from an infected cholesteatoma was measured in the presence of GV or FAC. METHODS: OPPA8 and PAO1 expressing a green fluorescent protein plasmid (pMRP9-1) was inoculated into a glass flow chamber. Biofilms were grown under low flow conditions for 48 hours and subsequently exposed to either GV or FAC for an additional 24 hours. Biofilm formation was visualized by confocal laser microscopy and biofilm volume was assayed by measuring fluorescence. Planktonic cultures were grown under standard conditions with GV or FAC. Statistical analysis was performed by Student t test and one-way ANOVA. RESULTS: GV reduced PAO1 and OPPA8 biofilm volume (P < .01). GV delayed the onset and rate of logarithmic growth in both strains. FAC reduced OPPA8 biofilm volume (P < .01), but did not effect of PAO1 biofilms. FAC had no effect on planktonic growth. CONCLUSIONS: The efficacy of GV in disrupting biofilms in vitro suggests that it may disrupt biofilms in vivo. The effect of FAC on Pseudomonas aeruginosa biofilms is strain dependent. Strain differences in response to increasing iron concentration and biofilm morphology stress the importance of studying clinically isolated strains in testing antibiofilm agents.

Tumor immunotherapy by epicutaneous immunization requires langerhans cells.

A role for Langerhans cells (LC) in the induction of immune responses in the skin has yet to be conclusively demonstrated. We used skin immunization with OVA protein to induce immune responses against OVA-expressing melanoma cells. Mice injected with OVA-specific CD8(+) T cells and immunized with OVA onto barrier-disrupted skin had increased numbers of CD8(+) T cells in the blood that produced IFN-gamma and killed target cells. These mice generated accelerated cytotoxic responses after secondary immunization with OVA. Prophylactic or therapeutic immunization with OVA onto barrier-disrupted skin inhibited the growth of B16.OVA tumors. LC played a critical role in the immunization process because depletion of LC at the time of skin immunization dramatically reduced the tumor-protective effect. The topically applied Ag was presented by skin-derived LC in draining lymph nodes to CD8(+) T cells. Thus, targeting of tumor Ags to LC in vivo is an effective strategy for tumor immunotherapy.

Langerhans cells cross-present antigen derived from skin.

Dendritic cells (DC) efficiently cross-present exogenous antigen on MHC class I molecules to CD8+ T cells. However, little is known about cross-presentation by Langerhans cells (LC), the DCs of the epidermis. Therefore, we investigated this issue in detail. Isolated murine LCs were able to cross-present soluble ovalbumin protein on MHC-class I molecules to antigen-specific CD8+ T cells, albeit less potently than the CD8+ DC subsets from spleen. Furthermore, LCs cross-presented cell-associated ovalbumin peptide and protein expressed by neighboring keratinocytes. Use of transporter associated with antigen processing (TAP-1)-deficient mice suggested a TAP-dependent pathway. Similar observations were made with migratory LC. Antigen expressed in the epidermis was ingested by LCs during migration from the epidermis and presented to antigen-specific T cells in vitro. Cross-presentation of ovalbumin protein by LCs induced IFN-gamma production and cytotoxicity in antigen-specific CD8+ T cells. Additionally, epicutaneous application of ovalbumin protein induced in vivo proliferation of OT-I T cells in the draining lymph nodes; this was markedly enhanced when antigen was applied to inflamed, barrier-disrupted skin. Thus, LCs cross-present exogenous antigen to CD8+ T cells and induce effector functions, like cytokine production and cytotoxicity, and may thereby critically contribute in epicutaneous vaccination approaches.