Neutrophils Deficient in Innate Suppressor IRAK-M Enhances Anti-tumor Immune Responses.

Tumor-associated immune-suppressive neutrophils are prevalent in various cancers, including colorectal cancer. However, mechanisms of immune-suppressive neutrophils are not well understood. We report that a key innate suppressor, IRAK-M (interleukin-1 receptor-associated kinase M), is critically involved in the establishment of immune-suppressive neutrophils. In contrast to the wild-type (WT) neutrophils exhibiting immune-suppressive signatures of CD11bhighPD-L1highCD80low, IRAK-M-deficient neutrophils are rewired with reduced levels of inhibitory molecules PD-L1 and CD11b, as well as enhanced expression of stimulatory molecules CD80 and CD40. The reprogramming of IRAK-M-deficient neutrophils is mediated by reduced activation of STAT1/3 and enhanced activation of STAT5. As a consequence, IRAK-M-deficient neutrophils demonstrate enhanced capability to promote, instead of suppress, the proliferation and activation of effector T cells both in vitro and in vivo. Functionally, we observed that the transfusion of IRAK-M-/- neutrophils can potently render an enhanced anti-tumor immune response in the murine inflammation-induced colorectal cancer model. Collectively, our study defines IRAK-M as an innate suppressor for neutrophil function and reveals IRAK-M as a promising target for rewiring neutrophils in anti-cancer immunotherapy.

Dipeptidyl peptidases as survival factors in Ewing sarcoma family of tumors: implications for tumor biology and therapy.

Ewing sarcoma family of tumors (ESFT) is a group of aggressive pediatric malignancies driven by the EWS-FLI1 fusion protein, an aberrant transcription factor up-regulating specific target genes, such as neuropeptide Y (NPY) and its Y1 and Y5 receptors (Y5Rs). Previously, we have shown that both exogenous NPY and endogenous NPY stimulate ESFT cell death via its Y1 and Y5Rs. Here, we demonstrate that this effect is prevented by dipeptidyl peptidases (DPPs), which cleave NPY to its shorter form, NPY(3-36), not active at Y1Rs. We have shown that NPY-induced cell death can be abolished by overexpression of DPPs and enhanced by their down-regulation. Both NPY treatment and DPP blockade activated the same cell death pathway mediated by poly(ADP-ribose) polymerase (PARP-1) and apoptosis-inducing factor (AIF). Moreover, the decrease in cell survival induced by DPP inhibition was blocked by Y1 and Y5R antagonists, confirming its dependence on endogenous NPY. Interestingly, similar levels of NPY-driven cell death were achieved by blocking membrane DPPIV and cytosolic DPP8 and DPP9. Thus, this is the first evidence of these intracellular DPPs cleaving releasable peptides, such as NPY, in live cells. In contrast, another membrane DPP, fibroblast activation protein (FAP), did not affect NPY actions. In conclusion, DPPs act as survival factors for ESFT cells and protect them from cell death induced by endogenous NPY. This is the first demonstration that intracellular DPPs are involved in regulation of ESFT growth and may become potential therapeutic targets for these tumors.

Anti-PD-L1 F(ab) Conjugated PEG-PLGA Nanoparticle Enhances Immune Checkpoint Therapy.

Background: Immune checkpoint therapies are effective in the treatment of a subset of patients in many different cancers. Immunotherapy offers limited efficacy in part because of rapid drug clearance and off-target associated toxicity. PEG-PLGA is a FDA approved, safe, biodegradable polymer with flexible size control. The delivery of immune checkpoint inhibitors such as anti-PD-L1 (α-PD-L1) via PEG-PLGA polymer has the potential to increase bioavailability and reduce immune clearance to enhance clinical efficacy and reduce toxicity. Methods: The Fc truncated F(ab) portion of α-PD-L1 monoclonal antibody (α-PD-L1 mAb) was attached to a PEG-PLGA polymer. α-PD-L1 F(ab)-PEG-PLGA polymers were incubated in oil-in-water emulsion to form a α-PD-L1 F(ab)-PEG-PLGA nanoparticle (α-PD-L1 NP). α-PD-L1 NP was characterized for size, polarity, toxicity and stability. The relative efficacy of α-PD-L1 NP to α-PD-L1 mAb was measured when delivered either intraperitoneally (IP) or intravenously (IV) in a subcutaneous mouse colon cancer model (MC38). Antibody retention was measured using fluorescence imaging. Immune profile in mice was examined by flow cytometry and immunohistochemistry. Results: Engineered α-PD-L1 NP was found to have pharmacological properties that are potentially advantageous compared to α-PD-L1 mAb. The surface charge of α-PD-L1 NP was optimal for both tumor cell uptake and reduced self-aggregation. The modified size of α-PD-L1 NP reduced renal excretion and mononuclear phagocyte uptake, which allowed the NP to be retained in the host system longer. α-PD-L1 NP was non-toxic in vitro and in vivo. α-PD-L1 NP comparably suppressed MC38 tumor growth. α-PD-L1 NP appeared to elicit an increased immune response as measured by increase in germinal center area in the spleen and in innate immune cell activation in the tumor. Finally, we observed that generally, for both α-PD-L1 NP and α-PD-L1 mAb, the IP route was more effective than IV route for tumor reduction. Conclusion: α-PD-L1 NP is a non-toxic, biocompatible synthetic polymer that can extend α-PD-L1 antibody circulation and reduce renal clearance while retaining anti-cancer activity and potentially enhancing immune activation.

Enhanced Mucosal Defense and Reduced Tumor Burden in Mice with the Compromised Negative Regulator IRAK-M.

Aberrant inflammation is a hallmark of inflammatory bowel disease (IBD) and colorectal cancer. IRAK-M is a critical negative regulator of TLR signaling and overzealous inflammation. Here we utilize data from human studies and Irak-m-/- mice to elucidate the role of IRAK-M in the modulation of gastrointestinal immune system homeostasis. In human patients, IRAK-M expression is up-regulated during IBD and colorectal cancer. Further functional studies in mice revealed that Irak-m-/- animals are protected against colitis and colitis associated tumorigenesis. Mechanistically, our data revealed that the gastrointestinal immune system of Irak-m-/- mice is highly efficient at eliminating microbial translocation following epithelial barrier damage. This attenuation of pathogenesis is associated with expanded areas of gastrointestinal associated lymphoid tissue (GALT), increased neutrophil migration, and enhanced T-cell recruitment. Further evaluation of Irak-m-/- mice revealed a splice variant that robustly activates NF-κB signaling. Together, these data identify IRAK-M as a potential target for future therapeutic intervention.

The effect of prosthesis alignment on the symmetry of gait in subjects with unilateral transtibial amputation.

A high degree of gait symmetry is characteristic of healthy gait. The aim of this study is to examine the symmetry of various gait parameters in subjects with unilateral trans-tibial amputation over a range of acceptable anteroposterior translational and tilt alignments, and further to examine if a consistent alignment of highest symmetry can be found. Acceptable alignments were determined by bench, static and dynamic testing on level and non-level surfaces. A total of 15 kinetic and kinematic parameters were then measured in the seven subjects participating in this study. Results indicate that some parameters show consistently higher symmetries, particularly the vertical ground reaction force parameters and the stance duration, step length and time to full knee flexion during the swing phase. Symmetries in other parameters such as knee flexion at loading response, acceleration impulse, and peak anteroposterior propulsive force seem to have little relevance in determining whether the gait pattern for that prosthetic alignment is acceptable or not. While analysis of the symmetry of more relevant gait parameters may assist the prosthetist in consistently and objectively identifying a most symmetrical alignment within the acceptable range, further clinical study is required before any conclusions can be drawn regarding evaluation of symmetry as a tool in defining any optimum alignment.

Is it important to position foot in subtalar joint neutral position during non-weight-bearing molding for foot orthoses?

When taking molds for foot orthoses, it is accepted practice to position the subtalar joint in its neutral position. However, foot orthoses have no contact with the talus, and this leads to a hypothesis that as long as there is correction available to appropriately align the forefoot relative to the hindfoot when taking a mold, changes in subtalar joint angles do not lead to significant alterations in the plantar surface shapes of the molds taken. This study tested this presumption with 20 subjects between 22 and 46 years old. During non-weight-bearing casting, the subtalar joints were aligned at positions of 4° of eversion, 2° of eversion, 2° of inversion, and in neutral. At each orientation, forces were applied over the forefoot such that the metatarsal heads were aligned with the rearfoot. Digital scanning was used to analyze the shape of each negative mold. There were significant changes in projection volume in different subtalar joint orientations. However, the changes in arch heights, navicular height, and protrusion were insignificant and very small. It is therefore suggested that as long as the forefoot and hindfoot are appropriately aligned, variations in the orientation of the subtalar joint would be acceptable.

The interaction between physical and social-psychological factors in indoor environmental health.

Indoor environmental health is now recognized as an important factor in preventing respiratory health problems in the United States. It is also a concern in Canada due to the amount of time that Canadians spend indoors because of cold weather and the potential for increased time indoors during the summer if the climate warms. The negative health effects are often labeled as sick building syndrome, but diagnosing a building or its occupants as sick is complicated by the variety of symptoms, the presence of chronic versus acute symptoms and social and psychological (socio-psychological) factors that may reduce the effectiveness of an engineering solution. As a case study, the contribution of various factors to indoor environmental health, in three buildings at the University of Toronto, was examined using five different methods. The results indicate that the inhabitants of the buildings consider features other than air quality in considering building health such as design, maintenance, funding cuts and socio-psychological factors.