CD8+ cytotoxic T cell responses to dominant tumor-associated antigens are profoundly weakened by aging yet subdominant responses retain functionality and expand in response to chemotherapy

Increasing life expectancy is associated with increased cancer incidence, yet the effect of cancer and anti-cancer treatment on elderly patients and their immune systems is not well understood. Declining T cell function with aging in response to infection and vaccination is well documented, however little is known about aged T cell responses to tumor antigens during cancer progression or how these responses are modulated by standard chemotherapy. We examined T cell responses to cancer in aged mice using AE17sOVA mesothelioma in which ovalbumin (OVA) becomes a 'spy' tumor antigen containing one dominant (SIINFEKL) and two subdominant (KVVRFDKL and NAIVFKGL) epitopes. Faster progressing tumors in elderly (22-24 months, cf. 60-70 human years) relative to young (2-3 months, human 15-18 years) mice were associated with increased pro-inflammatory cytokines and worsened cancer cachexia. Pentamer staining and an in-vivo cytotoxic T lymphocyte (CTL) assay showed that whilst elderly mice generated a greater number of CD8⁺ T cells recognizing all epitopes, they exhibited a profound loss of function in their ability to lyse targets expressing the dominant, but not subdominant, epitopes compared to young mice. Chemotherapy was less effective and more toxic in elderly mice however, similar to young mice, chemotherapy expanded CTLs recognizing at least one subdominant epitope in tumors and draining lymph nodes, yet treatment efficacy still required CD8⁺ T cells. Given the significant dysfunction associated with elderly CTLs recognizing dominant epitopes, our data suggest that responses to subdominant tumor epitopes may become important when elderly hosts with cancer are treated with chemotherapy.

Evaluation of the bioactivity of fluoride-enriched mineral trioxide aggregate on osteoblasts

AIM

To investigate whether a combination of mineral trioxide aggregate (MTA) and fluoride compounds affects bone cells.

METHODOLOGY

Mineral trioxide aggregate (MTA) discs (ProRoot^® , Dentsply Sirona, Ballaigues, Switzerland) with and without the addition of 0.1%, 0.25% and 0.5% sodium fluoride were characterized for their surface roughness by laser scanning microscopy and for the adhesion of human alveolar osteoblasts by scanning electron microscopy. Using eluates from fluoride-enriched MTA discs, the cell proliferation was measured by monitoring the DNA incorporation of 5-bromo-2'-deoxyuridine. Further, gene expression was evaluated by qPCR arrays, extracellular matrix mineralization was quantified by absorption measurement of Alizarin red stains, and effects were calculated with repeated measures analysis and post hoc P-value adjustment.

RESULTS

Irrespective of fluoride addition, cell adhesion was similar on MTA discs, of which the surface roughness was comparable. Control osteoblasts had a curvilinear proliferation pattern peaking at d5, which was levelled out by incubation with MTA. The addition of fluoride partly restored the MTA-related reduction in the cellular proliferation rate in a dose-dependent manner. At the mRNA level, both fluoride and MTA modulated a number of genes involved in osteogenesis, bone mineral metabolism and extracellular matrix formation. Although MTA significantly impaired extracellular matrix mineralization, the addition of fluoride supported the formation of mineralized nodules in a dose-dependent manner.

CONCLUSION

The addition of fluoride modulated the biocompatibility of MTA in terms of supporting bone cell proliferation and hard tissue formation. Hence, fluoride enrichment is a trend-setting advancement for MTA-based endodontic therapies.

Environmental Biomechanics Substantiated by Defined Pillar Micropatterns Govern Behavior of Human Mesenchymal Stem Cells

While evidence on the impact of the biomechanical environment elasticity on human mesenchymal stem cell (hMSC) behavior is growing, the aspect of micropatterning is still poorly understood. Thus, the present study aimed at investigating the influence of defined environmental micropatterning on hMSC behavior. Following characterization, hMSCs were grown on defined pillar micropatterns of 5, 7, 9, and 11 μm. With respect to cell behavior, primary hMSC adhesion was detected by indirect immunofluorescence (iIF) for paxillin, vinculin, integrin αV, and actin, while proliferation was visualized by histone H3. Morphogenesis was monitored by scanning electron microscopy and the expression of stem cell-specific biomarkers by real-time PCR. Favoritism of primary adhesion of hMSCs on pillar tops occurred at smaller pillar micropatterns, concomitant with cell flattening. While vinculin, integrin αV, and paxillin appeared initially more cytoplasmic, high pillar micropatterns favored a progressive redistribution with polarization to cell tension sites and at cell borders. Accomplishment of morphogenesis at day 3 revealed establishment of fully rotund cell somata at 5 μm, while hMSCs appeared progressively elongated at rising micropatterns. The hMSC proliferation capacity was influenced by pillar micropatterns and gene expression analysis of stem cell- and differentiation-associated biomarkers disclosed clear modulation by distinct pillar micropatterns. In response to environmental biomechanics, our results show that hMSC behavior is governed by pillar micropatterning. In turn, these findings may form the basis to prospectively direct lineage specificity of hMSCs in a customized fashion.

Adenoviral-mediated p53 gene transfer to non-small cell lung cancer through endobronchial injection

OBJECTIVE

The objective was to determine the degree of toxicity and antitumor activity following bronchoscopic injection of an adenoviral-mediated p53 gene (Adp53) into tumors causing airway obstruction. DOSING: This was a subset analysis of a phase I dose escalation trial.

SETTING

Patients were treated in the outpatient clinics at the University of Texas (MD Anderson Cancer Center, Houston, TX) and at Medical City Dallas Hospital (US Oncology, Dallas, TX).

PATIENTS

Twelve patients (median age, 60 years) with advanced endobronchial non-small cell lung cancer (NSCLC) (squamous cell carcinoma, six patients; adenocarcinoma, six patients) were entered into trial. The median tumor area was 5 x 3.2 cm. All patient tumors contained a p53 gene mutation.

INTERVENTIONS

Adp53 (dose range, 1 x 10(6) to 1 x 10(11) plaque-forming units) was administered by bronchoscopic intratumoral injection once every 28 days.

MEASUREMENTS AND RESULTS

Toxicity attributed to the Adp53 vector was minimal. Six of the 12 patients had significant improvement in airway obstruction, and 3 patients met the criteria for partial response.

CONCLUSIONS

Direct bronchoscopic injection of Adp53 into endobronchial NSCLC is safe, with acceptable levels of toxicity. The initial clinical results demonstrating relief of airway obstruction warrant further clinical investigation.

Resting respiratory tract dendritic cells preferentially stimulate T helper cell type 2 (Th2) responses and require obligatory cytokine signals for induction of Th1 immunity

Consistent with their role in host defense, mature dendritic cells (DCs) from central lymphoid organs preferentially prime for T helper cell type 1 (Th1)-polarized immunity. However, the "default" T helper response at mucosal surfaces demonstrates Th2 polarity, which is reflected in the cytokine profiles of activated T cells from mucosal lymph nodes. This study on rat respiratory tract DCs (RTDCs) provides an explanation for this paradox. We demonstrate that freshly isolated RTDCs are functionally immature as defined in vitro, being surface major histocompatibility complex (MHC) II lo, endocytosishi, and mixed lymphocyte reactionlo, and these cells produce mRNA encoding interleukin (IL)-10. After ovalbumin (OVA)-pulsing and adoptive transfer, freshly isolated RTDCs preferentially stimulated Th2-dependent OVA-specific immunoglobulin (Ig)G1 responses, and antigen-stimulated splenocytes from recipient animals produced IL-4 in vitro. However, preculture with granulocyte/macrophage colony stimulating factor increased their in vivo IgG priming capacity by 2-3 logs, inducing production of both Th1- and Th2-dependent IgG subclasses and high levels of IFN-gamma by antigen-stimulated splenocytes. Associated phenotypic changes included upregulation of surface MHC II and B7 expression and IL-12 p35 mRNA, and downregulation of endocytosis, MHC II processing- associated genes, and IL-10 mRNA expression. Full expression of IL-12 p40 required additional signals, such as tumor necrosis factor alpha or CD40 ligand. These results suggest that the observed Th2 polarity of the resting mucosal immune system may be an inherent property of the resident DC population, and furthermore that mobilization of Th1 immunity relies absolutely on the provision of appropriate microenvironmental costimuli.