Chronic postsurgical pain and persistent opioid use following surgery: the need for a transitional pain service

AIM

To identify the 3-month incidence of chronic postsurgical pain and long-term opioid use in patients at the Toronto General Hospital.

METHODS

200 consecutive patients presenting for elective major surgery completed standardized questionnaires by telephone at 3 months after surgery.

RESULTS

51 patients reported a preoperative chronic pain condition, with 12 taking opioids preoperatively. 3 months after surgery 35% of patients reported having surgical site pain and 13.5% continued to use opioids for postsurgical pain relief. Postoperative opioid use was associated with interference with walking and work, and lower mood.

CONCLUSION

Chronic postsurgical pain and ongoing opioid use are concerns that warrant the implementation of a Transitional Pain Service to modify the pain trajectories and enable effective opioid weaning following major surgery.

Transforming growth factor-β1 sustains the survival of Foxp3(+) regulatory cells during late phase of oropharyngeal candidiasis infection

As CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) play crucial immunomodulatory roles during infections, one key question is how these cells are controlled during antimicrobial immune responses. Mechanisms controlling their homeostasis are central to ensure efficient protection against pathogens, as well as to control infection-associated immunopathology. Here we studied how their viability is regulated in the context of mouse oropharyngeal candidiasis (OPC) infection, and found that these cells show increased protection from apoptosis during late phase of infection and reinfection. Tregs underwent reduced cell death because they are refractory to T cell receptor restimulation-induced cell death (RICD). We confirmed their resistance to RICD, using mouse and human Tregs in vitro, and by inducing α-CD3 antibody-mediated apoptosis in vivo. The enhanced viability is dependent on increased transforming growth factor-β1 (TGF-β1) signaling that results in upregulation of cFLIP (cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein) in Tregs. Protection from cell death is abrogated in the absence of TGF-β1 signaling in Tregs during OPC infection. Taken together, our data unravel the previously unrecognized role of TGF-β1 in promoting Treg viability, coinciding with the pronounced immunomodulatory role of these cells during later phase of OPC infection, and possibly other mucosal infections.

Abstract A036: Anti-PD1 therapy and CD8 T cell invigoration in metastatic melanoma

Antibodies targeting the PD-1 pathway can reverse T cell exhaustion resulting in re-invigoration of immune responses. Anti-PD1 therapies such as pembrolizumab have been shown to be efficacious across a broad range of human cancers including melanoma with clinical responses correlating with immune changes in the tumor microenvironment. However, our understanding of the immune mechanism of anti-PD1 therapy in humans remains incomplete. Specifically, there is relatively little information about changes in the differentiation, activation and reversal of exhaustion in peripheral blood CD8 T cells and correlation with clinical outcome. We collected peripheral blood at serial time points before and after pembrolizumab therapy on 39 consecutive patients with Stage IV melanoma and analyzed changes in T cell subsets and differentiation using 16 parameter flow cytometry. Here we show that pembrolizumab treatment results in increases in the peripheral blood CD8/Treg ratio, as well as invigoration of CD8 T cells. Focusing on key CD8 T cell subsets expressing combinations of T-bet, Eomes, PD-1 and other inhibitory receptors has allowed greater focus on populations responding to re-invigoration by pembrolizumab treatment. This invigoration can be demonstrated by upregulation of granzyme B (GzmB) and Ki67 in key CD8 T cell subsets. An early increase in GzmB+Ki67+ cells translates into a later increase in GzmB+ cells suggesting an early wave of proliferation giving rise to a pool of re-invigorated CD8 T cells. T cell subsets that express markers of exhaustion including T-bet, Eomes, and inhibitory receptors may represent populations that are invigorated by anti-PD1 therapy. These changes may also correlate with clinical outcomes and therefore may be useful as a biomarker of response. These results show that T cell responses to pembrolizumab treatment can be tracked in an easily accessible peripheral blood compartment during therapy. The kinetics of immune response in key CD8 T cell subsets may inform us of optimal treatment duration as well as the nature and timing of cancer response to therapy.

Citation Format: Alexander Huang, Wei Xu, Shannon Harmon, Felix Quagliarello, Ramin Herati, Kristen Pauken, Bertram Bengsch, Lynn Schuchter, Ravi Amaravadi, Suzanne McGettigan, Tara Gangadhar, John Wherry. Anti-PD1 therapy and CD8 T cell invigoration in metastatic melanoma. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A036.

Metabolic flux ratio analysis and cell staining suggest the existence of C4 photosynthesis in Phaeodactylum tricornutum

AIMS

Mechanisms for carbon fixation via photosynthesis in the diatom Phaeodactylum tricornutum Bohlin were studied recently but there remains a long-standing debate concerning the occurrence of C4 photosynthesis in this species. A thorough investigation of carbon metabolism and the evidence for C4 photosynthesis based on organelle partitioning was needed.

METHODS AND RESULTS

In this study, we identified the flux ratios between C3 and C4 compounds in P. tricornutum using (13)C-labelling metabolic flux ratio analysis, and stained cells with various cell-permeant fluorescent probes to investigate the likely organelle partitioning required for single-cell C4 photosynthesis. Metabolic flux ratio analysis indicated the C3/C4 exchange ratios were high. Cell staining indicated organelle partitioning required for single-cell C4 photosynthesis might exist in P. tricornutum.

CONCLUSION

The results of (13)C-labelling metabolic flux ratio analysis and cell staining suggest single-cell C4 photosynthesis exists in P. tricornutum.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides insights into photosynthesis patterns of P. tricornutum and the evidence for C4 photosynthesis based on (13)C-labelling metabolic flux ratio analysis and organelle partitioning.

Neuroprotective effect of astaxanthin against glutamate-induced cytotoxicity in HT22 cells: Involvement of the Akt/GSK-3β pathway

Oxidative stress (OS) mediated the pathogenesis of Alzheimer's disease (AD). Astaxanthin (ATX) has been reported to exert antioxidant activities as well as neuroprotective effects in vivo and in vitro. But it is still unknown whether the Akt/glycogen synthase kinase-3β (GSK-3β) signaling mediated the neuroprotective effect of ATX in HT22 cells. Flow cytometric analysis was used to evaluate reactive oxygen species (ROS) generation. Caspase and PARP activity was measured. The expressions of heme oxygenase-1 (HO-1), nuclear factor-E2-related factor 2 (Nrf2), Bcl-2, Bax, apoptosis-inducing factor (AIF), cytochrome-c (Cyto-c), p-Akt and p-GSK-3β were evaluated to elucidate the underlying mechanism. Our results showed that ATX significantly attenuated glutamate-induced cell viability loss and lactate dehydrogenase (LDH) release, decreased the expression of caspase-3/8/9 activity and cleaved PARP, and suppressed the intracellular accumulation of ROS in HT22 cells after exposure to glutamate. ATX also increased the mitochondrial expression of AIF, Cyto-c as well as Bax while decreased Bcl-2. Moreover, ATX also induced the HO-1 expression in a dose and time-dependent manner, increased the antioxidant-responsive element (ARE) activity and nuclear Nrf2 expression. Furthermore, treatment with ATX restored the p-Akt and p-GSK-3β (Ser9) as well as HO-1 expression reduced by glutamate. This protective effect was partially blocked by the inhibitors lithium chloride treatment in HT22, indicating the involvement of Akt/GSK-3β inactivation during the neuroprotective effect of ATX. Our results provide the first evidence that ATX can protect glutamate-induced cytotoxicity in HT22 via attenuating caspase activation and mitochondrial dysfunction and modulating the Akt/GSK-3β signaling, indicating ATX may be useful for the treatment of neurodegenerative disorders such as AD.