A study of high-lift airfoils at high Reynolds numbers in the Langley low-turbulence pressure tunnel

An experimental study was conducted in the Langley Low Turbulence Pressure Tunnel to determine the effects of Reynolds number and Mach number on the two-dimensional aerodynamic performance of two supercritical type airfoils, one equipped with a conventional flap system and the other with an advanced high lift flap system. The conventional flap system consisted of a leading edge slat and a double slotted, trailing edge flap with a small chord vane and a large chord aft flap. The advanced flap system consisted of a leading edge slat and a double slotted, trailing edge flap with a large chord vane and a small chord aft flap. Both models were tested with all elements nested to form the cruise airfoil and with the leading edge slat and with a single or double slotted, trailing edge flap deflected to form the high lift airfoils. The experimental tests were conducted through a Reynolds number range from 2.8 to 20.9 x 1,000,000 and a Mach number range from 0.10 to 0.35. Lift and pitching moment data were obtained. Summaries of the test results obtained are presented and comparisons are made between the observed aerodynamic performance trends for both models. The results showing the effect of leading edge frost and glaze ice formation is given

IFNγ-induced PD-L1 expression is JAK2 but not JAK1 dependent and its inhibition enhances NK-cetuximab mediated ADCC of HNSCC cells

Programmed death ligand 1 (PD-L1) is an immunosuppressive molecule expressed by many cancer types, including a large proportion of head and neck cancers (HNC), and ligation of its receptor, programmed death 1 (PD-1), induces exhaustion of effector T cells. It has been shown that interferon gamma (IFNγ) induces PD-L1 expression in many cancer types including glioblastoma, melanoma, lung and kidney cancer. Importantly, the stimuli and mechanism for PD-L1 upregulation in HNC cells are not well characterized. IFNγ signals through Janus Kinase 1/2 (JAK1/2) heterodimer complex and mediates signal transducer and activator of transcription 1 (STAT1) phosphorylation, leading to type I cytokine expression, upregulation of antigen presentation, and tumor cell recognition by cytolytic T lymphocytes (CTL). We investigated basal PD-L1 expression and the mechanism by which IFNγ signaling upregulates PD-L1 in HNC cells including dependence on JAK/STAT pathway. We observed that IFNγ signaling increased PD-L1 expression in a JAK2 but not JAK1 dependent fashion. In addition, interferon alpha (IFNα), which signals via JAK1/TYK2 did not upregulate PD-L1 expression while still upregulated HLA class I. Specific JAK2 inhibition downregulated NK cell-derived IFNγ induced PD-L1 expression and enhanced cetuximab mediated ADCC. Our data suggest a crucial role for JAK2/STAT1 in IFNγ mediated PD-L1 upregulation. JAK2 inhibition provides a promising strategy to increase tumor cell lysis through maintaining HLA class I while suppressing tumor cell expressed PD-L1 in combination with anti-EGFR cetuximab therapy

Reversing EGFR Mediated Immunoescape by Targeted Monoclonal Antibody Therapy

Uncontrolled growth is a signature of carcinogenesis, in part mediated by overexpression or overstimulation of growth factor receptors. The epidermal growth factor receptor (EGFR) mediates activation of multiple oncogenic signaling pathways and escape from recognition by the host immune system. We discuss how EGFR signaling downregulates tumor antigen presentation, upregulates suppressive checkpoint receptor ligand programmed death ligand (PD-L1), induces secretion of inhibitory molecules such as transforming growth factor beta (TGFβ) and reprograms the metabolic pathways in cancer cells to upregulate aerobic glycolysis and lactate secretion that ultimately lead to impaired cellular immunity mediated by natural killer (NK) cell and cytotoxic T lymphocytes (CTL). Ultimately, our understanding of EGFR-mediated escape mechanisms has led us to design EGFR-specific monoclonal antibody therapies that not only inhibit tumor cell metabolic changes and intrinsic oncogenic signaling but also activates immune cells that mediate tumor clearance. Importantly, targeted immunotherapy may also benefit from combination with antibodies that target other immunosuppressive pathways such PD-L1 or TGFβ and ultimately enhance clinical efficacy

EGFR-mediated tumor immunoescape: The imbalance between phosphorylated STAT1 and phosphorylated STAT3

The epidermal growth factor receptor (EGFR) supports the escape of malignant cells from immunosurveillance by inhibiting the activation of signal transducer and activator of transcription 1 (STAT1) while promoting that of STAT3. We have recently demonstrated that protein tyrosine phosphatase, non-receptor type 11 (PTNP11, best known as SHP2), a phosphatase that operates downstream of EGFR, is responsible for the dephosphorylation of active STAT1 and for the inhibition of the antigen-processing machinery (APM), hence favoring tumor immunoescape. Thus, EGFR signaling may skew the tumor microenvironment to suppress cellular immune responses

PD-1/SHP-2 negatively regulate Tc1/Th1 phenotypic responses and activation of T cells in the tumor microenvironment

Rejection of tumor cells by a robust cellular immune response relies on production of type 1 cytokines (such as IFN-γ) and cytolytic activity of T cells. Programmed Death 1 (PD-1), a co-inhibitory receptor proposed to represent T cell dysfunction, is highly expressed on tumor infiltrating lymphocytes (TIL) [1], and may reflect T cell exhaustion marked by decreased proliferation, production of type 1 cytokines and poor cytolytic activity [2]. T-bet, a T-box transcription factor which can be activated by phosphorylated signal transducers and activators of transcription 1 (p-STAT1), plays an important role in Tc1/Th1 skewing. Although anti-PD-1 antibodies enhance IFN-γ secretion after TCR stimulation [3], the mechanistic link between PD-1 and Tc1/Th1 skewing remains unclear. In prospectively collected cancer tissues, TIL manifested dampened Tc1/Th1 skewing and activation compared to PBL (Figure 1 and 2). In addition, PD-1 triggering using PD-L1 coated beads further suppressed TCR-stimulated upregulation of p-STAT1, T-bet and p-S6 as well as Th1 cytokines, while PD-1 blockade reversed suppressive effects of PD-1: PD-L1 ligation (Figure 3). We also found that Src homology-2 domain-containing phosphatase (SHP-2) is higher in TIL than in PBL, tightly correlates with PD-1 expression (Figure 4), and negatively regulates STAT1 and T-bet activation (Figure 5). Thus, the PD-1/SHP-2/p-STAT1/T-bet axis provides an important mechanism for PD-1 suppression of type 1 immunity at tumor sites. PD-1 blocking Abs, which are clinically effective in several solid cancers, should improve T cell-based cancer immunotherapy by restoring robust type 1 immunity and T cell activation to reverse immunosuppression in the tumor microenvironment. SHP-2 inhibitory strategies may also be useful to improve type 1-biased TIL

STAT1 contributes to HLA class I upregulation and CTL reactivity after anti-EGFR mAb cetuximab therapy in head and neck cancer patients

Squamous cell carcinoma of head and neck (HNSCC) cells express low HLA class I and antigen processing machinery (APM) components, such as transporter TAP-1/2, which is associated with the reduced sensitivity to cytotoxic T lymphocyte (CTL) mediated lysis. Epidermal growth factor receptor (EGFR) is overexpressed in HNSCC and is associated with the poor prognosis. FDA approved anti-EGFR blockade mAb cetuximab inhibits HNSCC proliferation, and induces EGFR-specific CTL. However, the molecular mechanism(s) underlying the EGFR-specific CTL recognition of HNSCC in the therapeutic efficacy of anti-EGFR mAb is still emerging. We show that cetuximab or EGFR knockdown enhanced expression of HLA class I antigens, which is associated with the EGFR expression level on HNSCC. These findings were validated in a prospective trial of neoadjuvant cetuximab therapy. Interestingly, upregulation of HLA-B/C alleles were more pronounced than HLA-A alleles after cetuximab or EGFR knockdown treatment. EGFR signaling blockade or EGFR depletion also enhanced IFN gamma receptor (IFNAR) on HNSCC and augmented induction of HLA class I and TAP-1/2 caused by IFN gamma treatment. Cetuximab or EGFR knockdown enhanced the level of HLA class I, STAT-1, TAP-1/2 in a STAT-1+/+ cell line but not in STAT-1-/- cell line, documenting the STAT-1 dependence of this effect. We also found that Src homology domain-containing phosphatase 2 (SHP-2), which is downstream of EGFR and also overexpressed in SCCHN, can suppress the immunostimulatory effect of cetuximab treatment on HLA class I/STAT-1 upregulation, and dual targeting of EGFR and SHP-2 co-operates in the most efficient reversal of immune escape phenotype. In addition, cetuximab-based EGFR inhibition and SHP-2 depletion enhanced the recognition of HNSCC cells by EGFR 853-861 specific CTL, and enhanced surface presentation of non-EGFR TA, such as MAGE-3 271-279 , indicating that a broad tumor antigen repertoire is processed and presented by HLA/APM upregulation. These findings elucidate a novel immune escape mechanism associated with EGFR signaling through STAT1 suppression and the reversal with cetuximab, which may provide additional targets for on-going mAb-based immunotherapy

Differential expression of PD-1 and Tim-3 marks activation versus exhaustion status of T cells in the tumor microenvironment

Programmed Death 1 (PD-1) and T cell Ig and mucin domain-3 protein (Tim-3) are two immune checkpoint receptors (ICR) highly co-expressed on tumor infiltrating T lymphocytes (TIL). PD-1 has been shown to inhibit T cell activation and type 1 T cell responses, while Tim-3 has been proposed as a further marker of exhaustion on TIL [1, 2], leading us to investigate the phenotypic and functional characteristics of TIL with differential PD-1 and Tim-3 expression from head and neck cancer (HNC) patients. Our data showed that PD-1+Tim-3+ CD8+ and Foxp3- CD4+ TILs manifested high phosphorylated signal transducers and activators of transcription 1 (p-STAT1) and the associated Th1 transcription factor T-bet, which might correlate with T cell exhaustion, both at baseline and upon TCR stimulation. Moreover, the sorted PD-1+Tim-3+ CD8+ TILs expressed the lowest IFN-γ and TNF-α transcripts and the least amount of secreted IFN-γ upon TCR stimulation, indicating they are the most dysfunctional T cells in the tumor microenvironment (TME). Among CD4+CD25lo/- TIL subsets, PD-1hiTim-3- cells are more defective in terms of IFN-γ expression. Sorted PD-1intTim-3- CD8+ and CD4+CD25lo/- TILs showed higher TCR-stimulated expression of IFN-γ and TNF-α transcripts and secretion of IFN-γ, suggesting they are the most activated subsets. In addition, sorted PD-1+Tim-3+ and PD-1hiTim-3- TIL were less proliferative than other subsets, concomitant with lower expression of phosphorylated S6 (p-S6), while PD-1intTim-3-, PD-1-Tim-3+ and PD-1-Tim-3- TIL retained p-S6 activation or proliferation, suggesting that high expression of PD-1 on T cells interferes with TCR or Tim-3 signaling and associated cellular activation status. Taken together, PD-1+Tim-3+ and PD-1hiTim-3- TIL are most dysfunctional, while PD-1intTim-3- TIL are more activated in terms of both Th1 cytokine production and proliferation. These results provide a better understanding of the functional status of TIL subsets and roles of PD-1 and Tim-3 in regulating anti-tumor T cell response, as targets for cancer immunotherapy

PD-1 blockade upregulate TIM-3 expression as a compensatory regulation of immune check point receptors in HNSCC TIL

Programmed Death 1 (PD-1) and T cell Ig and mucin domain-3 protein (Tim-3) are immune check point receptors that are upregulated on tumor infiltrating lymphocytes (TIL) in tumor-bearing mice and humans. As anti-PD-1 single agent response rates are still relatively low (20%) in HNC patients, it is important to learn how different inhibitory check point receptors work together to maintain the suppressive status of immune system. We observed that PD-1 and Tim-3 co-expression is associated with an exhausted phenotype of HNSCC TIL of patients, demonstrating the highest PD-1 levels in Tim-3 double positive TIL. We also observed that PD-1+/Tim-3+ TIL manifest dampened in Akt/p-S6 activation upon TCR stimulation, leading us to infer the potential for signaling cross-talk between PD-1 and Tim-3 downstream signaling pathways. Indeed, in freshly isolated HNSCC TIL, PD-1-/TIM-3+ T cells showed higher baseline expression of p-SHP-2 (p < 0.01) which is triggered upon PD-1 ligation. In addition, PD-1 blockade using nivolumab of human HNSCC TIL led to upregulation of Tim-3 expression, suggesting a circuit of compensatory, cross-talk signaling and permitting escape from anti-PD-1 blockade during TCR stimulation. In a murine HNC tumor model, anti-PD-1 treatment modestly suppressed tumor growth, but in TIL from persistent tumors in these mice, Tim-3 expression was dramatically upregulated after PD-1 blockade. Taken together, in response to PD-1 blockade, the most exhausted TIL appear to upregulate Tim-3 as a compensatory mechanism, supporting dual targeting, which may provide new therapeutic strategy for cancer immunotherapy

Coastal Ice-Core Record of Recent Northwest Greenland Temperature and Sea-Ice Concentration

Coastal ice cores provide an opportunity to investigate regional climate and sea-ice variability in the past to complement hemispheric-scale climate reconstructions from ice-sheet-interior ice cores. Here we describe robust proxies of Baffin Bay temperature and sea-ice concentration from the coastal 2Barrel ice core collected in the Thule region of northwest Greenland. Over the 1990–2010 record, 2Barrel annually averaged methanesulfonic acid (MSA) concentrations are significantly correlated with May–June Baffin Bay sea-ice concentrations and summer temperatures. Higher MSA is observed during warmer years with less sea ice, indicative of enhanced primary productivity in Baffin Bay. Similarly, 2Barrel annually averaged deuterium excess (d-excess) values are significantly correlated with annual Baffin Bay sea-ice concentrations and summer and annual temperatures. Warm (cool) years with anomalously low (high) sea-ice concentration are associated with proportionally more (less) low-d-excess Baffin Bay moisture at the ice-core site. Multilinear regression models incorporating 2Barrel MSA, d-excess and snow accumulation account for 38–51% of the Baffin Bay sea-ice and temperature variance. The annual temperature model is significantly correlated with temperatures throughout most of Greenland and eastern Arctic Canada due to the strong influence of the North Atlantic Oscillation and Atlantic Multidecadal Oscillation

Hypothenar hammer syndrome: Proposed etiology

AbstractPurpose: Finger ischemia caused by embolic occlusion of digital arteries originating from the palmar ulnar artery in a person repetitively striking objects with the heel of the hand has been termed hypothenar hammer syndrome (HHS). Previous reports have attributed the arterial pathology to traumatic injury to normal vessels. A large experience leads us to hypothesize that HHS results from trauma to intrinsically abnormal arteries. Methods: We reviewed the arteriography, histology, and clinical outcome of all patients treated for HHS in a university clinical research center study of hand ischemia, which prospectively enrolled more than 1300 subjects from 1971 to 1998. Results: Twenty-one men had HHS. All had occupational (mechanic, carpenter, etc) or avocational (woodworker) exposure to repetitive palmar trauma. All patients underwent upper-extremity and hand arteriography, unilateral in eight patients (38%) and bilateral in 13 patients (62%). By means of arteriogram, multiple digital artery occlusions were shown in the symptomatic hand, with either segmental ulnar artery occlusion in the palm or characteristic “corkscrew” elongation, with alternating stenoses and ectasia. Similar changes in the contralateral asymptomatic (and less traumatized) hand were shown by means of 12 of 13 bilateral arteriograms (92%). Twenty-one operations, consisting of segmental ulnar artery excision in the palm and vein grafting, were performed on 19 patients. Histology was compatible with fibromuscular dysplasia with superimposed trauma. Patency of arterial repairs at 2 years was 84%. One patient (5%) required amputative debridement of necrotic finger tips. No other tissue loss occurred. There have been no recurrences of ischemia in patients with patent bypass grafts. Conclusion: To our knowledge, this is the largest reported group of HHS patients. The characteristic angiographic appearance, histologic findings, and striking incidence of bilateral abnormalities in patients with unilateral symptoms lead us to conclude that HHS occurs when persons with preexisting palmar ulnar artery fibrodysplasia experience repetitive palmar trauma. This revised theory for the etiology of HHS explains why HHS does not develop in most patients with repetitive palmar trauma. (J Vasc Surg 2000;31:104-13.