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Objective COVID-19 disproportionately impacts residents in long-term care facilities. Our objective was to quantify the presence and magnitude of antibody response in vaccinated, older adult residents at assisted living, personal care, and independent living communities. Design A cross-sectional quality improvement study was conducted March 15 – April 1, 2021 in the greater Pittsburgh region. Setting and Population: Participants were older adult residents at assisted living, personal care, and independent living communities, who received mRNA-based COVID-19 vaccine. Conditions that impair immune responses were exclusionary criteria. Methods Sera were collected to measure IgG anti-SARS-CoV-2 antibody level with reflex to total anti-SARS-CoV-2 immunoglobulin levels, and blinded evaluation of SARS-CoV-2 pseudovirus neutralization titers. Descriptive statistics, Pearson correlation coefficients, and multiple linear regression analysis evaluated relationships between factors potentially associated with antibody levels. Spearman correlations were calculated between antibody levels and neutralization titers. Results All participants (N = 70) had received two rounds of vaccination and were found to have antibodies with wide variation in relative levels. Antibody levels trended lower in males, advanced age, current use of steroids, and longer length of time from vaccination. Pseudovirus neutralization titer levels were strongly correlated (P < .001) with Beckman Coulter antibody levels (D614 G NT50, rs = 0.91; B.1.1.7 [UK] NT50, rs = 0.91). Conclusions and Implications Higher functioning, healthier, residential older adults mounted detectable antibody responses when vaccinated with mRNA-based COVID-19 vaccines. Data suggests some degree of immunity is present during the immediate period following vaccination. However, protective effects remain to be determined in larger studies as clinical protection is afforded by ongoing adaptive immunity, which is known to be decreased in older adults. This study provides important preliminary results on level of population risk in older adult residents at assisted living, personal care, and independent living communities to inform reopening strategies, but are not likely to be translatable for residents in nursing homes.

Therapeutic cancer vaccines targeting melanoma-associated antigens are commonly immunogenic but are rarely effective in promoting objective clinical responses. To identify critical molecules for activation of effective antitumor immunity, we have profiled autologous dendritic cell (DC) vaccines used to treat 35 patients with melanoma. We showed that checkpoint molecules induced by ex vivo maturation correlated with in vivo DC vaccine activity. Melanoma patient DCs had reduced expression of cell surface inducible T-cell costimulator ligand (ICOSL) and had defective intrinsic NF-κB signaling. Chromatin immunoprecipitation assays revealed NF-κB–dependent transcriptional regulation of ICOSL expression by DCs. Blockade of ICOSL on DCs reduced priming of antigen-specific CD8+ and CD4+ T cells from naïve donors in vitro. Concentration of extracellular/soluble ICOSL released from vaccine DCs positively correlated with patient clinical outcomes, which we showed to be partially regulated by ADAM10/17 sheddase activity. These data point to the critical role of canonical NF-κB signaling, the regulation of matrix metalloproteinases, and DC-derived ICOSL in the specific priming of cognate T-cell responses in the cancer setting. This study supports the implementation of targeted strategies to augment these pathways for improved immunotherapeutic outcomes in patients with cancer.

ObjectivesSerologic detection of prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is needed for definition of convalescent plasma donors, for confounding SARS-CoV-2 presentation, and for seroprevalence studies. Reliable serologic assays with independent validation are required.MethodsSix SARS-CoV-2 antibody assays from Beckman Coulter, Euroimmun (IgG, IgA), Roche, and Siemens (Centaur, Vista) were assessed for specificity (n = 184), sensitivity (n = 154), and seroconversion in a defined cohort with clinical correlates and molecular SARS-CoV-2 results.ResultsAssay specificity was 99% or greater for all assays except the Euroimmun IgA (95%). Sensitivity at more than 21 days from symptom onset was 84%, 95%, 72%, 98%, 67%, and 96% for Beckman Coulter, Centaur, Vista, Roche, Euroimmun IgA, and Euroimmun IgG, respectively. Average day of seroconversion was similar between assays (8-10 d), with 2 patients not producing nucleocapsid antibodies during hospitalization.ConclusionsSARS-CoV-2 nucleocapsid antibodies may be less reliably produced early in disease than spike protein antibodies. Assessment of convalescent plasma donors at more than 30 days from symptom onset and seroprevalence studies should use assays with defined sensitivity at time points of interest because not all assays detected antibodies reliably at more than 30 days.

Altered expressions of proto-oncogenes have been reported during normal lymphocytes mitogenesis and in T and B lymphocytes in patients with autoimmune diseases. We have recently demonstrated a significantly decreased expression of c-kit and c-Myc in NK cells isolated from patients with cancer, which might be related to the functional deficiency of NK cells in the tumor environment. Here, focusing on the regulatory mechanisms of this new clinical phenomenon, we determined expression of c-Myc, Notch1, Notch2, p-53, Cdk6, Rb and phosphorylated Rb in NK cells isolated from the healthy donors and cancer patients. The results of our study revealed a significant down-regulation of expression of Notch receptors and up-regulation of Cdk6 expression in NK cells in cancer, while no significant changes in the expression of p53 and Rb proteins were seen. These data revealed novel signaling pathways altered in NK cells in the tumor environment and support further investigation of the origin of deregulated expression of proto-oncogenes in NK cells patients with different types of cancer.

Knowledge about development and duration of virus-specific antibodies after COVID-19 vaccination is important for understanding how to limit the pandemic via vaccination in different populations and societies. However, the clinical utility of postvaccination testing of antibody response and selection of targeted SARS-CoV-2 antigen(s) has not been established. The results of such testing from clinical teams independent from vaccine manufacturers are also limited. Here, we report the initial results of an ongoing clinical study on evaluation of antibody response to four different SARS-CoV-2 antigens after first and second dose of Pfizer and Moderna mRNA vaccines and at later time points. We revealed a peak of antibody induction after the vaccine boosting dose with a gradual decline of antibody levels at later time. Anti-nucleocapsid antibody was not induced by spike protein-encoding vaccines and this may continue to serve as a marker of previous SARS-CoV-2 infection. No differences between the two vaccines in terms of antibody response were revealed. Age and gender dependencies were determined to be minimal within the healthy adult (but not aged) population. Our results suggest that postvaccination testing of antibody response is an important and feasible tool for following people after vaccination and selecting individuals who might require a third dose of vaccine at an earlier time point or persons who may not need a second dose due to previous SARS-CoV-2 infection. IMPORTANCE Now that authorized vaccines for COVID-19 have been widely used, it is important to understand how they induce antivirus antibodies, which antigens are targeted, how long antibodies circulate, and how personal health conditions and age may affect this humoral immunity. Here, we report induction and time course of multiple anti-SARS-CoV-2 antibody responses in healthy individuals immunized with Pfizer and Moderna mRNA vaccines. We also determined the age and gender dependence of the antibody response and compared antibody levels to responses seen in those who have recovered from COVID-19. Our results suggest the importance of screening for antibody response to multiple antigens after vaccination in order to reveal individuals who require early and late additional boosting and those who may not need second dose due to prior SARS-CoV-2 infection.

Objectives Detection of antibodies to multiple SARS-CoV-2 antigens in a single assay could increase diagnostic accuracy, differentiate vaccination from natural disease, and aid in retrospective exposure determination. Correlation of binding antibody assessment in clinical assays with neutralizing antibodies is needed to better understand the humoral response to SARS-CoV-2 infection and establish of correlates of protection. Methods A cohort of 752 samples was used to assess specificity, sensitivity, and comparison to 6 other Conformite Europeenne serologic assays for the BioRad SARS-CoV-2 IgG multiplex assay which measures receptor binding domain IgG (RBD), spike-S1 IgG (S1), spike-S2 IgG (S2), and nucleocapsid IgG (N). A subset of serial specimens from 14 patients was also tested for neutralizing antibodies (n = 61). Results Specificity for RBD and S1 IgG was 99.4% (n = 170) and 100% for S2 and N IgG (n = 170) in a cohort selected for probable interference. Overall assay concordance with other assays was >93% for IgG and total antibody assays and reached 100% sensitivity for clinical concordance at >14 days as a multiplex assay. RBD and S1 binding antibody positivity demonstrated 79–95% agreement with the presence of neutralizing antibodies. Conclusions The BioRad SARS-CoV-2 IgG assay is comparable to existing assays, and achieved 100% sensitivity when all markers were included. The ability to measure antibodies against spike and nucleocapsid proteins simultaneously may be advantageous for complex clinical presentations, epidemiologic research, and in decisions regarding infection prevention strategies. Additional independent validations are needed to further determine binding antibody and neutralizing antibody correlations.

BackgroundThe treatment of multiple myeloma (MM) has been revolutionized by the introduction of therapeutic monoclonal antibodies (tmAbs). Daratumumab, a human IgG1/κ tmAb against CD38 on plasma cells, has improved overall survival in refractory MM and was recently approved as a frontline therapy for MM. Work on tmAb interference with serum protein electrophoresis (SPE) during MM monitoring has failed to provide information for laboratories on incidence of interference and effective methods of managing the interference at a practicable level. We aimed to evaluate daratumumab and elotuzumab interference in a large academic hospital setting and implement immediate solutions.MethodsWe identified and chart reviewed all cases of possible daratumumab interference by electrophoretic pattern (120 of 1317 total cases over 3 months). We retrospectively reviewed SPE cases in our laboratory to assess clinical implications of tmAb interference before the laboratory was aware of tmAb treatment. We supplemented samples with daratumumab and elotuzumab to determine the limits of detection and run free light chain analysis.ResultsApproximately 9% (120 of 1317) of tested cases have an SPE and/or immunofixation electrophoresis (IFE) pattern consistent with daratumumab, but only approximately 47% (56) of these cases were associated with daratumumab therapy. Presence of daratumumab led to physician misinterpretation of SPE/IFE results. Limits of daratumumab detection varied with total serum gammaglobulin concentrations, but serum free light chain analysis was unaffected.ConclusionsClinical laboratories currently rely on interference identification by electrophoretic pattern, which may be insufficient and is inefficient. Critical tools in preventing misinterpretation efficiently include physician education, pharmacy notifications, separate order codes, and interpretive comments.

Ovarian cancer is the leading cause of death among gynecologic diseases in the USA and Europe. High-grade serous carcinoma (HGSC) of the ovary, the most aggressive type of ovarian cancer, is typically diagnosed at advanced stages when the 5-year survival is dismal. Since the cure rate for stage I HGSC is high, early detection of localized initial disease may improve patient outcomes. Serous tubal intraepithelial carcinoma (STIC) is considered to be a precursor lesion of HGSC. Discovery of biomarkers associated with STIC could aid in the development of an HGSC screening algorithm. Using immunohistochemical staining, we have demonstrated overexpression of UCHL1, ADAMTS13, and GAPDH in patients’ STIC lesions, but not in cancer-free fallopian tubes. We additionally demonstrated a marked increase of T cells in perineoplastic stroma surrounding STIC lesions (largely CD4 + cells), but not in normal fallopian tubes and HGSC. FOXP3 + T regulatory cells are absent in STIC lesions but are present in HGSC. These observations indicate the microenvironment surrounding a STIC lesion may be immune promoting in contrast to the immune suppressive microenvironment of invasive carcinoma. In summary, we have identified UCHL1, ADAMTS13, and GAPDH as novel potentially useful markers associated with early stages of HGSC tumorigenesis and possibly contribute to STIC immunogenicity. The lack of immune suppression in the STIC microenvironment indicates that the immune system can still recognize and keep STIC controlled at this stage of the tumor development.

The calcium-binding protein S100b is secreted by glial cells in the brain and is also expressed by melanocytes. In nanomolar concentrations, S100b is considered to be a neurotrophic factor, but in micromolar concentrations, it is thought to reflect CNS injury and inflammation. Seen as a potential biomarker in traumatic brain injury, meta-analytic data from several studies report that S100b levels are significantly higher in persons with long standing schizophrenia, but also among first-episode patients compared to healthy control subjects. However, ethnic or racial differences are typically not mentioned when reporting levels of S100b. We assessed serum S100b levels in persons with schizophrenia (n = 136) who were participants in two independent research studies using the same enzyme-linked immunoassay (ELISA). African-American subjects had significantly higher levels of S100b (41.9 pg/ml ± 62.2) than Caucasian subjects (24.9 pg/ml ± 45.4) in the combined dataset (Mann-Whitney U = 1307, p

Schwann cells are the principal glial cells of the peripheral nervous system which maintain neuronal homeostasis. Schwann cells support peripheral nerve functions and play a critical role in many pathological processes including injury-induced nerve repair, neurodegenerative diseases, infections, neuropathic pain and cancer. Schwann cells are implicated in a wide range of diseases due, in part, to their ability to interact and modulate immune cells. We discuss the accumulating examples of how Schwann cell regulation of the immune system initiates and facilitates the progression of various diseases. Furthermore, we highlight how Schwann cells may orchestrate an immunosuppressive tumor microenvironment by polarizing and modulating the activity of the dendritic cells.

The tumor microenvironment has been compared with a nonhealing wound involving a complex interaction between multiple cell types. Schwann cells, the key regulators of peripheral nerve repair, have recently been shown to directly affect nonneural wound healing. Their role in cancer progression, however, has been largely limited to neuropathic pain and perineural invasion. In this study, we showed that melanoma activated otherwise dormant functions of Schwann cells aimed at nerve regeneration and wound healing. Such reprogramming of Schwann cells into repair-like cells occurred during the destruction and displacement of neurons as the tumor expanded and via direct signaling from melanoma cells to Schwann cells, resulting in activation of the nerve injury response. Melanoma-activated Schwann cells significantly altered the microenvironment through their modulation of the immune system and the extracellular matrix in a way that promoted melanoma growth in vitro and in vivo. Local inhibition of Schwann cell activity following cutaneous sensory nerve transection in melanoma orthotopic models significantly decreased the rate of tumor growth. Tumor-associated Schwann cells, therefore, can have a significant protumorigenic effect and may present a novel target for cancer therapy.Significance:These findings reveal a role of the nerve injury response, particularly through functions of activated Schwann cells, in promoting melanoma growth.

At present, significant experimental and clinical data confirm the active involvement of the peripheral nervous system (PNS) in different phases of cancer development and progression. Most of the research effort focuses on the impact of distinct neuronal types, e.g., adrenergic, cholinergic, dopaminergic, etc. in carcinogenesis, generally ignoring neuroglia. The very fact that these cells far outnumber the other cellular types may also play an important role worthy of study in this context. The most prevalent neuroglia within the PNS consists of Schwann cells (SCs). These cells play a substantial role in maintaining homeostasis within the nervous system. They possess distinct immunomodulatory, inflammatory and regenerative capacities-also, one should consider their broad distribution throughout the body; this makes them a perfect target for malignant cells during the initial stages of cancer development and the very formation of the tumor microenvironment itself. We show that SCs in the tumor milieu attract different subsets of immune regulators and augment their ability to suppress effector T cells. SCs may also up-regulate invasiveness of tumor cells and support metastatic disease. We outline the interactive potential of SCs juxtaposed with cancerous cells, referring to data from various external sources alongside data of our own.

Seroprevalence studies are important for understanding the dynamics of local virus transmission and evaluating community immunity. To assess the seroprevalence for SARS-CoV-2 in Allegheny County, an urban/suburban county in Western PA, 393 human blood samples collected in Fall 2020 and February 2021 were examined for spike protein receptor-binding domain (RBD) and nucleocapsid protein (N) antibodies. All RBD-positive samples were evaluated for virus-specific neutralization activity. Our results showed a seroprevalence of 5.5% by RBD ELISA, 4.5% by N ELISA, and 2.5% for both in Fall 2020, which increased to 24.7% by RBD ELISA, 14.9% by N ELISA, and 12.9% for both in February 2021. Neutralization titer was significantly correlated with RBD titer but not with N titer. Using these two assays, we were able to distinguish infected from vaccinated individuals. In the February cohort, higher median income and white race were associated with serological findings consistent with vaccination. This study demonstrates a 4.5-fold increase in SARS-CoV-2 seroprevalence from Fall 2020 to February 2021 in Allegheny County, PA, due to increased incidence of both natural disease and vaccination. Future seroprevalence studies will need to include the effect of vaccination on assay results and incorporate non-vaccine antigens in serological assessments.

ObjectiveCOVID-19 disproportionately impacts older adults residing at long-term care facilities. Data regarding antibody response to COVID-19 vaccines in this population is limited. Our objective was to quantify the presence and magnitude of antibody response in older, vaccinated residents at assisted living, personal care, and independent living facilities.DesignA cross-sectional quality improvement study was conducted March 15 – April 1, 2021 in the Pittsburgh region.Setting and PopulationParticipants were volunteers at assisted living, personal care, and independent living facilities, who received mRNA COVID-19 vaccine. Conditions that obviate immune responses were exclusionary criteria.MethodsSera were collected to measure IgG anti-SARS-CoV-2 antibody level with reflex to total anti-SARS-CoV-2 immunoglobulin levels. Descriptive statistics, Pearson correlation coefficients, and multiple linear regression analysis were performed to evaluate relationships between factors potentially associated with antibody levels.ResultsAll participants (N=70) had received two rounds of vaccination for COVID-19 and were found to have antibodies to SARS-CoV-2. There was wide variation in relative levels of antibodies as determined by extinction coefficients. Antibody levels trended lower in male sex, advanced age, steroid medications, and longer length of time from vaccination.Conclusions and ImplicationsHigher functioning long-term care residents mounted detectable antibody responses when vaccinated with COVID-19 mRNA-based vaccines. This study provides preliminary information on level of population risk of assisted living, personal care, and independent living residents which can inform reopening strategies. Data suggests some degree of immunity is present during the immediate period following vaccination. However, protective effects of such vaccination programs remain to be determined in larger studies. Clinical protection is afforded not just by pre-formed antibody levels, but by ongoing adaptive immunity, which is known to be decreased in older individuals. Thus, the implications of these levels of antibodies in preventing COVID-19 disease must be determined by clinical follow-up.

Surgery remains an essential therapeutic approach for most solid malignancies. Although for more than a century accumulating clinical and experimental data have indicated that surgical procedures themselves may promote the appearance and progression of recurrent and metastatic lesions, only in recent years has renewed interest been taken in the mechanism by which metastasizing of cancer occurs following operative procedures. It is well proven now that surgery constitutes a risk factor for the promotion of pre-existing, possibly dormant micrometastases and the acceleration of new metastases through several mechanisms, including the release of neuroendocrine and stress hormones and wound healing pathway-associated immunosuppression, neovascularization, and tissue remodeling. These postoperative consequences synergistically facilitate the establishment of new metastases and the development of pre-existing micrometastases. While only in recent years the role of the peripheral nervous system has been recognized as another contributor to cancer development and metastasis, little is known about the contribution of tumor-associated neuronal and neuroglial elements in the metastatic disease related to surgical trauma and wound healing. Specifically, although numerous clinical and experimental data suggest that biopsy- and surgery-induced wound healing can promote survival and metastatic spread of residual and dormant malignant cells, the involvement of the tumor-associated neuroglial cells in the formation of metastases following tissue injury has not been well understood. Understanding the clinical significance and underlying mechanisms of neuroimmune regulation of surgery-associated metastasis will not only advance the field of neuro–immuno–oncology and contribute to basic science and translational oncology research but will also produce a strong foundation for developing novel mechanism-based therapeutic approaches that may protect patients against the oncologically adverse effects of primary tumor biopsy and excision.

Background While it is presumed that immunosuppressed patients, such as solid organ transplant recipients on immunosuppression, are at greater risk from SARS-CoV-2 infection than the general population, the antibody response to infection in this patient population has not been studied. Methods In this report, we follow the anti-SARS-CoV-2 antibody levels in patients with COVID-19 who are undergoing exogenous immunosuppression. Specifically, we studied the antibody response of 3 solid organ transplant recipient patients, 3 patients who take daily inhaled fluticasone, and a patient on etanercept and daily inhaled fluticasone, and compared them to 5 patients not on exogenous immunosuppression. Results We found that the solid organ transplant patients on full immunosuppression are at risk of having a delayed antibody response and poor outcome. We did not find evidence that inhaled steroids or etanercept predispose patients to delayed immune response to SARS-CoV-2. Conclusion The data presented here suggest that solid organ transplant recipients may be good candidates for early targeted intervention against SARS-CoV-2.

Highlights • Euroimmun SARS-CoV-2 IgG, IgA tests have specificity of 99% and 86% • Specificity can be improved using competitive blocking step with recombinant spike protein. • Hospitalized COVID-19 patients median IgA seroconversion was 8 days and IgG 10 days. • Neither antibody level nor timing of antibody response correlated with days on ventilation., Objectives Humoral immune response to SARS-CoV-2 infection has been reported in several patient cohorts with results that vary by method and population studied due to the lack of reliable commercial assays available as the pandemic initially spread. We sought to clinically assess commercial prototype SARS-CoV-2 IgG and IgA assays for use in screening for prior infection and convalescent plasma donation. Design and Methods: Prototype SARS-CoV-2 IgG and IgA assays from Euroimmun were assessed utilizing remnant specimens. Specificity testing used specimens in their convalescent window for the common coronaviruses and other infectious diseases known to be associated with increased non-specificity in serologic assays. Sensitivity testing utilized serial specimens from molecularly confirmed SARS-CoV-2 critically ill patients to assess seroconversion. Utilizing recombinant spike protein we also developed a competitive confirmation procedure to increase assay specificity. Results We determined specificity to be 97% and 81%, respectively, when indeterminate samples were considered positive and 99% and 86% when indeterminate samples were considered negative. We developed a new confirmation methodology to enhance the specificity of the assays with an anticipated specificity of 98% for IgA. Valuation of hospitalized COVID-19 patients determined median IgA seroconversion to be 8 days and IgG 10 days. Neither level nor timing of antibody response correlated with days on ventilation. End titer measurements indicate that validated improved assays may be capable of semi-quantitative measurement. Conclusions We found these assays to be clinically acceptable for the high prevalence population tested, for instance, for convalescent plasma donation.

Cancer cells evade the immune system through a variety of different mechanisms, including the inhibition of antitumor effector T cells via checkpoint ligand-receptor interaction. Moreover, studies have shown that blocking these checkpoint pathways can reinvigorate the antitumor immunity, thereby prompting the development of numerous checkpoint immunotherapies, several of which are now being approved to treat multiple types of cancer. However, only a fraction of patients achieves promising long-term outcomes in response to checkpoint inhibition, suggesting the existence of additional unknown tumor-induced immunosuppressive pathways. In this issue of the JCI, Klement and colleagues describe an additional pathway of T cell inhibition in cancer. Specifically, the authors demonstrate that downregulation of IRF8, a molecular determinant of apoptotic resistance, in tumor cells aborts repression of osteopontin, which in turn binds to its physiological receptor CD44 on activated T cells and suppresses their activation. These results suggest that osteopontin may act as another immune checkpoint and may serve as a target to expand the number of patients who respond to immune checkpoint inhibitor therapy.

The role of deregulated expression of oncogenes and tumor-suppressor genes in tumor development has been intensively investigated for decades. However, expression of oncogenes and their potential role in immune cell defects during carcinogenesis and tumor progression have not been thoroughly assessed. The defects in proto-oncogenes have been well documented and evaluated mostly in tumor cells, despite the fact that proto-oncogenes are expressed in all cells, including cells of the immune system. In this review, key studies from immune-mediated diseases that may be associated with oncogene signaling pathways are refocused to provide groundwork for beginning to understand the effects of oncogenes in and on the cancer-related immune system dysfunction.

PURPOSE OF THE STUDY: A number of in vivo studies have shown that pulmonary exposure to carbon nanotubes (CNTs) may lead to an acute local inflammatory response, pulmonary fibrosis, and granulomatous lesions. Among the factors that play direct roles in initiation and progression of fibrotic processes are epithelial-mesenchymal transition and myofibroblasts recruitment/differentiation, both mediated by transforming growth factor-β1 (TGF-β1). Yet, other contributors to TGF-β1 associated signaling, such as osteopontin (OPN) has not been fully investigated. MATERIALS AND METHODS: OPN-knockout female mice (OPN-KO) along with their wild-type (WT) counterparts were exposed to single-walled carbon nanotubes (SWCNT) (40 μg/mouse) via pharyngeal aspiration and fibrotic response was assessed 1, 7, and 28 days post-exposure. Simultaneously, RAW 264.7 and MLE-15 cells were treated with SWCNT (24 hours, 6 μg/cm(2) to 48 μg/cm(2)) or bleomycin (0.1 μg/ml) in the presence of OPN-blocking antibody or isotype control, and TGF-β1 was measured in supernatants. RESULTS AND CONCLUSIONS: Diminished lactate dehydrogenase activity at all time points, along with less pronounced neutrophil influx 24 h post-exposure, were measured in broncho-alveolar lavage (BAL) of OPN-KO mice compared to WT. Pro-inflammatory cytokine release (IL-6, TNF-α, MCP-1) was reduced. A significant two-fold increase of TGF-β1 was found in BAL of WT mice at 7 days, while TGF-β1 levels in OPN-KO animals remained unaltered. Histological examination revealed marked decrease in granuloma formation and less collagen deposition in the lungs of OPN-KO mice compared to WT. RAW 264.7 but not MLE-15 cells exposed to SWCNT and bleomycin had significantly less TGF-β1 released in the presence of OPN-blocking antibody. We believe that OPN is important in initiating the cellular mechanisms that produce an overall pathological response to SWCNT and it may act upstream of TGF-β1. Further investigation to understand the mechanistic details of such interactions is critical to predict outcomes of pulmonary exposure to CNT.

Introduction C-kit/SCF signaling plays a key role in regulating NK cell homeostasis, maturation, proliferation, and cytotoxicity. C-kit-deficiency in NK cells results in significant reduction of their number, suggesting an imperative role for c-kit signaling in NK cell biology. We have recently showed that human NK cells express not only c-kit-receptor, but also both membrane-bound and soluble forms of c-kit ligand—Stem cell factor. The goal of this study was to characterize the c-kit/SCF autocrine loop in peripheral blood NK cells obtained from patients with cancer. Methods Using Smart Flare and qRT-PCR, we have characterized expression of c-kit and two forms of SCF in patients’ NK cells and correlated these results with the expression of c-myc and STAT3. Results Our results demonstrated that the expression of proto-oncogenes c-myc and c-kit was significantly decreased in NK cells from all cancer patients. Expression of membrane-bound SCF in NK cells correlated with the presence of remote metastases. Conclusions We suggest that the abnormal signaling and expression of c-kit/SCF, c-myc, and STAT3 in NK cells is responsible for the defect in their cytolytic activity in cancer and these defects at the gene expression level may be the cause rather than the result of tumor progression.

Objectives Multiple myeloma (MM) is characterized by malignant growth of plasma cells, usually producing a monoclonal antibody (mAb). New treatments for MM include therapeutic monoclonal antibodies (tmAbs), but patients treated with tmAb demonstrate interference on serum electrophoresis (SPE) and immunoprecipitation electrophoresis (IEP). Evaluation of treatment efficacy and determination of MM remission include SPE and IEP which identifies mAb, but cannot differentiate between disease associated mAb and tmAb. We hypothesized that tmAb could be removed from patient sera before testing by SPE and IEP to provide accurate diagnoses for clinicians. Design and methods We developed the Antigen Specific therapeutic monoclonal Antibody Depletion Assay (ASADA), that utilizes magnetic beads coated with the cognate antigen of the tmAbs, to deplete two different tmAb (daratumumab, elotuzumab) from saline and patient sera and assessed for complete removal of tmAb by SPE and IEP. Results We found that tmAb could be efficiently removed from saline and patient sera. ASADA demonstrated acceptable analytical specificity and sensitivity in IEP. Recovery of appropriate quantitative values by SPE was demonstrated with clinically acceptable precision. A single bead cocktail could be used to treat both daratumumab and elotuzumab. Conclusions This demonstrates proof of principle that ASADA can be used to remove current and future tmAb from patient sera, regardless of platform. This research provides for accurate diagnosis, disease monitoring, and remission status in MM patients being treated with tmAb.

Cancer is a complex ecosystem and should be considered in the context of its cellular and molecular microenvironment, which includes the nerves. Peripheral nerves can modulate phenotype and behavior of the malignant cells and thus affect tumor growth and metastasis. Only recently has the role of neuroimmune cross-talk surfaced as a key contributor to cancer progression. However, little is known about the immunomodulatory role of the neuroglial cells in cancer progression and metastasis and the response to therapy. Schwann cells, the principal glial cells of the peripheral nervous system, are now considered to be important players in the tumor microenvironment. They can directly accelerate malignant cell migration and the formation of metastases. Better understanding of the neuroimmune circuits in the tumor milieu will be instrumental in the development of novel therapeutic approaches for the malignancies known to be associated with inflammation and dysregulated immune responses.

Interleukin-1β (IL-1β) is abundant in the tumor microenvironment, where this cytokine can promote tumor growth, but also antitumor activities. We studied IL-1β during early tumor progression using a model of orthotopically introduced 4T1 breast cancer cells. Whereas there is tumor progression and spontaneous metastasis in wild-type (WT) mice, in IL-1β–deficient mice, tumors begin to grow but subsequently regress. This change is due to recruitment and differentiation of inflammatory monocytes in the tumor microenvironment. In WT mice, macrophages heavily infiltrate tumors, but in IL-1β–deficient mice, low levels of the chemokine CCL2 hamper recruitment of monocytes and, together with low levels of colony-stimulating factor-1 (CSF-1), inhibit their differentiation into macrophages. The low levels of macrophages in IL-1β–deficient mice result in a relatively high percentage of CD11b+ dendritic cells (DCs) in the tumors. In WT mice, IL-10 secretion from macrophages is dominant and induces immunosuppression and tumor progression; in contrast, in IL-1β–deficient mice, IL-12 secretion by CD11b+ DCs prevails and supports antitumor immunity. The antitumor immunity in IL-1β–deficient mice includes activated CD8+ lymphocytes expressing IFN-γ, TNF-α, and granzyme B; these cells infiltrate tumors and induce regression. WT mice with 4T1 tumors were treated with either anti–IL-1β or anti–PD-1 Abs, each of which resulted in partial growth inhibition. However, treating mice first with anti–IL-1β Abs followed by anti–PD-1 Abs completely abrogated tumor progression. These data define microenvironmental IL-1β as a master cytokine in tumor progression. In addition to reducing tumor progression, blocking IL-1β facilitates checkpoint inhibition.

Cancerous cells must cooperate with the surrounding stroma and non-malignant cells within the microenvironment to support the growth and invasion of the tumor. The nervous system is a component of every organ system of the body, and therefore, is invariably at the front line of the tumor invasion. Due to the complexity of the nervous system physiology, this review separately discusses the contributions of the central and peripheral nervous systems to the tumorigenesis and tumor progression. We further focus the discussion on the evidence that Schwann cells aid in tumor growth and invasion. Schwann cells, a largely unexplored element of the tumor microenvironment, may participate in the creation of tumor-favorable conditions through both bi-directional interaction with cancer cells and the facilitation of the immune-suppressive microenvironment through the mechanism of neural repair and immunomodulation.

The members of the TGFβ superfamily play a key role in regulating developmental and homeostasis programs by controlling differentiation, proliferation, polarization, and survival of different cell types. Although the role of TGFβ1 in inflammation and immunity is well evident, the contribution of other TGFβ family cytokines in the modulation of the antitumor immune response remains less documented. Here we show that activin A triggers SMAD2 and ERK1/2 pathways in dendritic cells (DC) expressing type I and II activin receptors, and upregulates production of the TNFα family cytokines BAFF (TALL-1, TNFSF13B) and APRIL (TALL-2, TNFSF13A), which is blocked by SMAD2 and ERK1/2 inhibitors, respectively. BAFF and APRIL derived from activin A–treated DCs upregulate proliferation and survival of T cells expressing the corresponding receptors, BAFF-R and TACI. In vivo, activin A–stimulated DCs demonstrate a significantly increased ability to induce tumor-specific CTLs and inhibit the growth of melanoma and lung carcinoma, which relies on DC-derived BAFF and APRIL, as knockdown of the BAFF and APRIL gene expression in activin A–treated DCs blocks augmentation of their antitumor potential. Although systemic administration of activin A, BAFF, or APRIL for the therapeutic purposes is not likely due to the pluripotent effects on malignant and nonmalignant cells, our data open a novel opportunity for improving the efficacy of DC vaccines. In fact, a significant augmentation of the antitumor activity of DC pretreated with activin A and the proven role of DC-derived BAFF and APRIL in the induction of antitumor immunity in vivo support this direction. Cancer Res; 76(17); 4959–69. ©2016 AACR.

Biopersistence of carbon nanotubes, graphene oxide (GO) and several other types of carbonaceous nanomaterials is an essential determinant of their health effects. Successful biodegradation is one of the major factors defining the life span and biological responses to nanoparticles. Here, we review the role and contribution of different oxidative enzymes of inflammatory cells - myeloperoxidase, eosinophil peroxidase, lactoperoxidase, hemoglobin, and xanthine oxidase - to the reactions of nanoparticle biodegradation. We further focus on interactions of nanomaterials with hemoproteins dependent on the specific features of their physico-chemical and structural characteristics. Mechanistically, we highlight the significance of immobilized peroxidase reactive intermediates vs diffusible small molecule oxidants (hypochlorous and hypobromous acids) for the overall oxidative biodegradation process in neutrophils and eosinophils. We also accentuate the importance of peroxynitrite-driven pathways realized in macrophages via the engagement of NADPH oxidase- and NO synthase-triggered oxidative mechanisms. We consider possible involvement of oxidative machinery of other professional phagocytes such as microglial cells, myeloid-derived suppressor cells, in the context of biodegradation relevant to targeted drug delivery. We evaluate the importance of genetic factors and their manipulations for the enzymatic biodegradation in vivo. Finally, we emphasize a novel type of biodegradation realized via the activation of the “dormant” peroxidase activity of hemoproteins by the nano-surface. This is exemplified by the binding of GO to cyt c causing the unfolding and “unmasking” of the peroxidase activity of the latter. We conclude with the strategies leading to safe by design carbonaceous nanoparticles with optimized characteristics for mechanism-based targeted delivery and regulatable life-span of drugs in circulation.

Dendritic cells (DC) play unique and diverse roles in the tumor occurrence, development, progression and response to therapy. First of all, DC can actively uptake tumor-associated antigens, process them and present antigenic peptides to T cells inducing and maintaining tumor-specific T cell responses. DC interaction with different immune effector cells may also support innate antitumor immunity, as well as humoral responses also known to inhibit tumor development in certain cases. On the other hand, DC are recruited to the tumor site by specific tumor-derived and stroma-derived factors, which may also impair DC maturation, differentiation and function, thus resulting in the deficient formation of antitumor immune response or development of DC-mediated tolerance and immune suppression. Identification of DC-stimulating and DC-suppressing/polarizing factors in the tumor environment and the mechanism of DC modulation are important for designing effective DC-based vaccines and for recovery of immunodeficient resident DC responsible for maintenance of clinically relevant antitumor immunity in patients with cancer. DC-targeting tumor-derived factors and their effects on resident and administered DC in the tumor milieu are described and discussed in this review.

Michael R Shurin1,21Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; 2Department of Immunology, University of Pittsburgh Medical Center, Pittsburgh, PA, USADuring the last decade, we have witnessed exhilarating progress in the expansion of immunotherapeutic approaches to cancer treatment. In part, this has been because of discovery and development of antibodies which can block immune inhibitory receptors unleashing antitumor immune responses – the so-called checkpoint inhibitors. Blocking cancer progression by eliminating brakes on immune effector cells in the tumor environment has jointly earned James P Allison, PhD (Department of Immunology, MD Anderson Cancer Center, University of Texas, Houston, TX, USA) and Tasuku Honjo, MD, PhD (Graduate School of Medicine, Kyoto University, Kyoto, Japan) the Nobel Prize in Physiology or Medicine in 2018. Whereas the concept of cancer immunosurveillance dates back more than 100 years, the study of Allison’s and Honjo’s teams over the past few decades not only confirmed the idea but also converted it into an effective immunotherapeutic tactic, which dramatically improved outcomes for some cancer patients.&nbsp

Tumor microenvironment is characterized by immunosuppressive mechanisms associated with the accumulation of immune regulatory cells - myeloid-derived suppressor cells (MDSC). Therapeutic depletion of MDSC has been associated with inhibition of tumor growth and therefore represents an attractive approach to cancer immunotherapy. MDSC in cancer are characterized by enhanced enzymatic capacity to generate reactive oxygen and nitrogen species (RONS) which have been shown to effectively degrade carbonaceous materials. We prepared enzymatically openable nitrogen-doped carbon nanotube cups (NCNC) corked with gold nanoparticles and loaded with paclitaxel as a therapeutic cargo. Loading and release of paclitaxel was confirmed through electron microscopy, Raman spectroscopy and LC-MS analysis. Under the assumption that RONS generated by MDSCs can be utilized as a dual targeting and oxidative degradation mechanism for NCNC, here we report that systemic administration of paclitaxel loaded NCNC delivers paclitaxel to circulating and lymphoid tissue MDSC resulting in the inhibition of growth of tumors (B16 melanoma cells inoculated into C57BL/6 mice) in vivo. Tumor growth inhibition was associated with decreased MDSC accumulation quantified by flow cytometry that correlated with bio-distribution of gold-corked NCNC resolved by ICP-MS detection of residual gold in mouse tissue. Thus, we developed a novel immunotherapeutic approach based on unique nanodelivery vehicles, which can be loaded with therapeutic agents that are released specifically in MDSC via NCNC selective enzymatic "opening" affecting change in the tumor microenvironment.

During the last decades, changes have been observed in the frequency of different histologic subtypes of lung cancer, one of the most common causes of morbidity and mortality, with a declining proportion of squamous cell carcinomas and an increasing proportion of adenocarcinomas, particularly in developed countries. This suggests the emergence of new etiologic factors and mechanisms, including those defining the lung microenvironment, promoting tumor growth. Assuming that the lung is the main portal of entry for broadly used nanomaterials and their established proinflammatory propensities, we hypothesized that nanomaterials may contribute to changes facilitating tumor growth. Here, we report that an acute exposure to single-walled carbon nanotubes (SWCNT) induces recruitment and accumulation of lung-associated myeloid-derived suppressor cells (MDSC) and MDSC-derived production of TGFβ, resulting in upregulated tumor burden in the lung. The production of TGFβ by MDSC requires their interaction with both SWCNT and tumor cells. We conclude that pulmonary exposure to SWCNT favors the formation of a niche that supports ingrowth of lung carcinoma in vivo via activation of TGFβ production by SWCNT-attracted and -presensitized MDSC. Cancer Res; 75(8); 1615–23. ©2015 AACR.

Development of metastasis is determined by both the accretion of essential changes in cancerous cells and by their communications with different stromal elements in the tumor microenvironment. Specifically, inflammatory response and emergence of immune regulatory cells, such and myeloid regulatory cells (macrophages, dendritic cells, neutrophils, myeloid-derived suppressor cells) and lymphoid regulatory cells (regulatory T, B and NK cells) to the tumor site have been reported to support tumor growth in addition to spreading and metastasis. Every phase of tumor progression, from its initiation through metastatic expansion, is endorsed by interaction between malignant and immune cells mediated by a number of growth factors, cytokines, proteases and other molecules that modify the tumor microenvironment. Invasion and metastasis depend on intratumoral vascularization, alterations of the basement membrane and degradation of the extracellular matrix for tumor cell spreading, invasion and extravasation into the blood and lymphatic vessels. The consequent dissemination of cancerous cells to distant tissues and organs necessitates a trafficking through the vasculature, which is promoted by further interactions with cells of the immune system, including myeloid regulatory cells. Moreover, the formation of the pre-metastatic niche and specific metastasis organ tropism is also regulated and controlled by bone marrow-derived hematopoietic immune progenitor cells, immature myeloid cells and certain cytokines, chemokines and growth factors derived from tumor and immune cells, which amend the local microenvironment of the organ or tissue to promote adhesion and survival of circulating cancerous cells. Although the potential role for myeloid regulatory cells in tumor spreading and development of pre-metastatic niche has been suggested, the concept still requires further supportive experimental and clinical data, as well as data related to specific factors and mechanisms responsible for myeloid regulatory cell functioning at malignant sites.

With the advancement of nanocarriers for drug delivery into biomedical practice, assessments of drug susceptibility to oxidative degradation by enzymatic mechanisms of inflammatory cells become important. Here, we investigate oxidative degradation of a carbon nanotube-based drug carrier loaded with Doxorubicin. We employed myeloperoxidase-catalysed and peroxynitrite-mediated oxidative conditions to mimic the respiratory burst of neutrophils and macrophages, respectively. In addition, we revealed that the cytostatic and cytotoxic effects of free Doxorubicin, but not nanotube-carried drug, on melanoma and lung carcinoma cell lines were abolished in the presence of tumor-activated myeloid regulatory cells that create unique myeloperoxidase- and peroxynitrite-induced oxidative conditions. Both ex vivo and in vitro studies demonstrate that the nanocarrier protects the drug against oxidative biodegradation.

Detection of malignant cells in tissue is a difficult hurdle in medical diagnostics and screening. Carbon nanotubes are extremely sensitive to their local environments, and nanotube-based field-effect transistors (NTFETs) provide a plethora of information regarding the mechanism of interaction with target analytes. Herein, we use a series of functionalized metal nanoparticle-decorated NTFET devices forming an array with multiple nonselective sensor units as the electronic “tongue”, sensing all five basic tastes. By extraction of selected NTFET characteristics and using linear discriminant analysis, we have successfully detected and discriminated between malignant and nonmalignant tissues and cells. We also studied the sensing mechanism and what NTFET characteristics are responsible for the variation of response between cell types, allowing for the design of future studies such as detection of malignant cells in a biopsy or the effects of malignant cells on healthy tissue.

With the rapid development of synthetic alternatives to mineral fibers, their possible effects on the environment and human health have become recognized as important issues worldwide. This study investigated effects of four fibrous materials, i.e. nanofibrillar/nanocrystalline celluloses (NCF and CNC), single-walled carbon nanotubes (CNTs), and crocidolite asbestos (ASB), on pulmonary inflammation and immune responses found in the lungs, as well as the effects on spleen and peripheral blood immune cell subsets. BALB/c mice were given NCF, CNC, CNT, and ASB on Day 1 by oropharyngeal aspiration. At 14 days post-exposure, the animals were evaluated. Total cell number, mononuclear phagocytes, polymorphonuclear leukocytes, lymphocytes, and LDH levels were significantly increased in ASB and CNT-exposed mice. Expression of cytokines and chemokines in bronchoalveolar lavage (BAL) was quite different in mice exposed to four particle types, as well as expression of antigen presentation-related surface proteins on BAL cells. The results revealed that pulmonary exposure to fibrous materials led to discrete local immune cell polarization patterns with a TH2-like response caused by ASB and TH1-like immune reaction to NCF, while CNT and CNC caused non-classical or non-uniform responses. These alterations in immune response following pulmonary exposure should be taken into account when testing the applicability of new nanosized materials with fibrous morphology.

The great majority of studies exploring potential pathogenic effects of engineered nanomaterials have been conducted in study settings mimicking the effects in healthy individuals, but only part of the world’s population belongs to this group. A significant proportion of the population has impaired health conditions, such as allergy and asthma that are believed to make these individuals more susceptible to additional health risks from particulate exposure. In this chapter, we discuss the impact of engineered nanomaterials, in particular, carbon nanotubes, on allergic pulmonary inflammation and asthma.

Myeloid derived suppressor cells (MDSC) represent only a minor fraction of circulating blood cells but play an important role in tumor formation and progression. They are a heterogeneous group of cells that influence the tumor microenvironment by depletion of amino acids, oxidative stress, decreased trafficking of antitumor effector cells, and increased regulatory T and regulatory dendritic cell responses. Investigational treatment strategies targeting MDSCs have attempted to inhibit MDSC development and expansion (stem cell factor blockade, modulate of cell signaling, and target MDSC migration and recruitment), inhibit MDSC function (nitric oxide inhibition and reactive oxygen and nitrogen species inhibition), differentiate MDSCs into more mature cells (Vitamins A and D, all-trans retinoic acid, interleukin-2, toll-like receptor 9 inhibitors, taxanes, beta-glucan particles, tumor-derived exosome inhibition, and very small size proteoliposomes), and destroy MDSCs (cytotoxic agents, ephrin A2 degradation, anti-interleukin 13, and histamine blockers). To date, there are no Food and Drug Administration approved therapies selectively targeting MDSCs, but such therapies are likely to be implemented in the future, due to the key role of MDSCs in antitumor immunity.

Altering the fuel source from petroleum-based ultra-low sulfur diesel to biodiesel and its blends is considered by many to be a sustainable choice for controlling exposures to particulate material. As the exhaust of biodiesel/diesel blends is composed of a combination of combustion products of polycyclic aromatic hydrocarbons and fatty acid methyl esters, we hypothesize that 50% biodiesel/diesel blend (BD50) exposure could induce harmful outcomes because of its ability to trigger oxidative damage. Here, adverse effects were compared in murine male reproductive organs after pharyngeal aspiration with particles generated by engine fueled with BD50 or neat petroleum diesel (D100). When compared with D100, exposure to BD50 significantly altered sperm integrity, including concentration, motility, and morphological abnormalities, as well as increasing testosterone levels in testes during the time course postexposure. Serum level of luteinizing hormone was significantly depleted only after BD50 exposure. Moreover, we observed that exposure to BD50 significantly increased sperm DNA fragmentation and the upregulation of inflammatory cytokines in the serum and testes on Day 7 postexposure when compared with D100. Histological evaluation of testes sections from BD50 exposure indicated more noticeable interstitial edema, degenerating spermatocytes, and dystrophic seminiferous tubules with arrested spermatogenesis. Significant differences in the level of oxidative stress assessed by accumulation of lipid peroxidation products and depletion of glutathione were detected on exposure to respirable BD50 and D100. Taken together, these results indicate that exposure of mice to inhalable BD50 caused more pronounced adverse effects on male reproductive function than diesel.

Several lines of evidence indicate that exposure to nanoparticles (NPs) is able to modify airway immune responses, thus facilitating the development of respiratory diseases. Graphene oxide (GO) is a promising carbonaceous nanomaterial with unique physicochemical properties, envisioned for a multitude of medical and industrial applications. In this paper, we determined how exposure to GO modulates the allergic pulmonary response. Using a murine model of ovalbumin (OVA)-induced asthma, we revealed that GO, given at the sensitization stage, augmented airway hyperresponsiveness and airway remodeling in the form of goblet cell hyperplasia and smooth muscle hypertrophy. At the same time, the levels of the cytokines IL-4, IL-5, and IL-13 were reduced in broncho-alveolar lavage (BAL) fluid in GO-exposed mice. Exposure to GO during sensitization with OVA decreased eosinophil accumulation and increased recruitment of macrophages in BAL fluid. In line with the cytokine profiles, sensitization with OVA in the presence of GO stimulated the production of OVA-specific IgG2a and down-regulated the levels of IgE and IgG1. Moreover, exposure to GO increased the macrophage production of the mammalian chitinases, CHI3L1 and AMCase, whose expression is associated with asthma. Finally, molecular modeling has suggested that GO may directly interact with chitinase, affecting AMCase activity, which has been directly proven in our studies. Thus, these data show that GO exposure attenuates Th2 immune response in a model of OVA-induced asthma, but leads to potentiation of airway remodeling and hyperresponsiveness, with the induction of mammalian chitinases.

Protumorigenic activity of immune regulatory cells has been proven to play a major role in precluding immunosurveillance and limiting the efficacy of anticancer therapies. Although several approaches have been offered to deplete myeloid-derived suppressor cells (MDSC) and regulatory T cells, there are no data on how to control suppressive dendritic cell (DC) accumulation or function in the tumor environment. Although immunosuppressive function of DC in cancer was implicated to immature and plasmacytoid DC, details of how conventional DC (cDC) develop immunosuppressive properties remain less understood. Here, we show that the development of lung cancer in mice was associated with fast accumulation of regulatory DC (regDC) prior to the appearance of MDSC. Using the in vitro and in vivo approaches, we demonstrated that (i)both cDC and MDSC could be polarized into protumor regDC in the lung cancer environment; (ii) cDC → regDC polarization was mediated by the small Rho GTPase signaling, which could be controlled by noncytotoxic doses of paclitaxel; and (iii) prevention of regDC appearance increased the antitumor potential of DC vaccine in lung cancer. These findings not only bring new players to the family of myeloid regulatory cells and provide new targets for cancer therapy, but offer novel insights into the immunomodulatory capacity of chemotherapeutic agents used in low, noncytotoxic doses.

The antitumor effects of paclitaxel are generally attributed to the suppression of microtubule dynamics resulting in defects in cell division. New data demonstrated that in ultralow noncytotoxic concentrations, paclitaxel modulated in immune cells in vitro the activity of small Rho GTPases, the key regulators of intracellular actin dynamics. However, the immunomodulatory properties of paclitaxel in vivo have not been evaluated. In this study, using the ret transgenic murine melanoma model, which mimics human cutaneous melanoma, we tested effects of ultralow noncytotoxic dose paclitaxel on functions of myeloid-derived suppressor cells (MDSCs), chronic inflammatory mediators, and T cell activities in the tumor microenvironment in vivo. Administration of paclitaxel significantly decreased accumulation and immunosuppressive activities of tumor-infiltrating MDSCs without alterations of the bone marrow hematopoiesis. This was associated with the inhibition of p38 MAPK activity, TNF-α and production, and S100A9 expression in MDSCs. The production of mediators of chronic inflammation in the tumor milieu also was diminished. Importantly, reduced tumor burden and increased animal survival upon paclitaxel application was mediated by the restoration of CD8 T cell effector functions. We suggest that the ability of paclitaxel in a noncytotoxic dose to block the immunosuppressive potential of MDSCs in vivo represents a new therapeutic strategy to downregulate immunosuppression and chronic inflammation in the tumor microenvironment for enhancing the efficacy of concomitant anticancer therapies.