HEMOPERFUSION USING THE LPS-SELECTIVE MESOPOROUS POLYMERIC ADSORBENT IN SEPTIC SHOCK: A MULTICENTER RANDOMIZED CLINICAL TRIAL

ABSTRACT

Extracorporeal hemoperfusion (EHP) may improve the course and outcomes of patients with septic shock by targeting cytokines or bacterial endotoxins (lipopolysaccharide [LPS]). Here, we present the results of a multicenter randomized controlled trial ( clinicaltrials.gov/ct2/show/NCT04827407 ) to assess the efficiency and safety of Efferon LPS hemoperfusion cartridges engineered for multimodal targeting LPS, host-derived cytokine, and damage-associated molecule pattern molecules. Patients with intra-abdominal sepsis (IAS) and septic shock (Sepsis-3) were subjected to EHP procedures (n = 38). Control patients with IAS and septic shock (n = 20) were treated using conventional protocols without EHP. The primary end point was resolution of septic shock. Secondary end points included MAP, vasopressor drug dose, partial pressure of arterial oxygen/fraction of inspired oxygen ratio, Sequential Organ Failure Assessment score, length of stay in the intensive care unit, and satisfaction with device use by a 5-point Likert scale. Clinical laboratory tests for a blood cells count, lactate and creatinine concentration, nephelometry test for C-reactive protein, immunochemiluminescent test for procalcitonin, and immunoenzyme analysis for IL-6 concentration were used to monitor the EHP effect versus the control group. Data were analyzed followed the intention-to-treat approach. Wilcoxon STATA 16.0 (StataCorp, College Station, TX) and Excel 2019 with XLStat 2019 add-in (Addinsoft, Paris, France) were used for statistical analysis of the results. The Fine and Gray method of competing risks was used to analyze the primary end point and other data representing the time to event. EHP resulted in a significant and rapid increase in MAP and partial pressure arterial oxygen/fraction of inspired oxygen ratio, progressive decline in norepinephrine doses, and multiorgan deficiency, as evaluated by Sequential Organ Failure Assessment scores. Importantly, EHP led to significantly rapid cumulative mechanical ventilation weaning compared with the control group (subdistribution hazard ratio, 2.5; P = 0.037). Early 3-day mortality was significantly reduced in the Efferon LPS versus control group; however, no significant improvements in survival in 14 and 28 days were revealed. Laboratory tests showed rapidly decreased levels of LPS, procalcitonin, C-reactive protein, IL-6, creatinine, leukocytes, and neutrophils only in the Efferon LPS group. Results demonstrate that EHP with Efferon LPS is a safe procedure to abrogate septic shock and normalize clinical and pathogenically relevant biomarkers in patients with IAS.

Peroxynitrite in the tumor microenvironment changes the profile of antigens allowing escape from cancer immunotherapy

Cancer immunotherapy often depends on recognition of peptide epitopes by cytotoxic T lymphocytes (CTLs). The tumor microenvironment (TME) is enriched for peroxynitrite (PNT), a potent oxidant produced by infiltrating myeloid cells and some tumor cells. We demonstrate that PNT alters the profile of MHC class I bound peptides presented on tumor cells. Only CTLs specific for PNT-resistant peptides have a strong antitumor effect in vivo, whereas CTLs specific for PNT-sensitive peptides are not effective. Therapeutic targeting of PNT in mice reduces resistance of tumor cells to CTLs. Melanoma patients with low PNT activity in their tumors demonstrate a better clinical response to immunotherapy than patients with high PNT activity. Our data suggest that intratumoral PNT activity should be considered for the design of neoantigen-based therapy and also may be an important immunotherapeutic target.

Transport coefficients of model lubricants up to 400 MPa from molecular dynamics

In this paper, the predictive power of molecular dynamics methods is demonstrated for the cases of model paraffinic and aromatic lubricant liquids at pressures up to 400 MPa. The shear viscosity and self-diffusion coefficients are calculated for 2,2,4-trimethylpentane (C₈H₁₈) at 298 K and 1,1-diphenylethane (C₁₄H₁₄) at 333 K. Three force fields with different levels of accuracy are compared by the ability to predict the experimental data. The Stokes-Einstein correlation between viscosity and self-diffusion is demonstrated for both compounds.

Tumor-infiltrating myeloid cells induce tumor cell resistance to cytotoxic T cells in mice

Cancer immunotherapeutic approaches induce tumor-specific immune responses, in particular CTL responses, in many patients treated. However, such approaches are clinically beneficial to only a few patients. We set out to investigate one possible explanation for the failure of CTLs to eliminate tumors, specifically, the concept that this failure is not dependent on inhibition of T cell function. In a previous study, we found that in mice, myeloid-derived suppressor cells (MDSCs) are a source of the free radical peroxynitrite (PNT). Here, we show that pre-treatment of mouse and human tumor cells with PNT or with MDSCs inhibits binding of processed peptides to tumor cell-associated MHC, and as a result, tumor cells become resistant to antigen-specific CTLs. This effect was abrogated in MDSCs treated with a PNT inhibitor. In a mouse model of tumor-associated inflammation in which the antitumor effects of antigen-specific CTLs are eradicated by expression of IL-1β in the tumor cells, we determined that therapeutic failure was not caused by more profound suppression of CTLs by IL-1β-expressing tumors than tumors not expressing this proinflammatory cytokine. Rather, therapeutic failure was a result of the presence of PNT. Clinical relevance for these data was suggested by the observation that myeloid cells were the predominant source of PNT in human lung, pancreatic, and breast cancer samples. Our data therefore suggest what we believe to be a novel mechanism of MDSC-mediated tumor cell resistance to CTLs.

Dendritic cell-based full-length survivin vaccine in treatment of experimental tumors

Survivin is a good candidate for cancer immunotherapy since it is overexpressed in most common human cancers, poorly expressed in most normal adult tissues and is essential for cancer cell survival. Previously, we and others have demonstrated that survivin-specific immune responses can be generated in mice and cancer patients. These responses resulted in a substantial antitumor effect. However, the fact that survivin is expressed in normal hematopoietic progenitor cells and endothelial cells may potentially limit the use of vaccination against survivin in the clinic due to possible toxicity. In this study, we have evaluated this risk by using dendritic cells (DC) transduced with an adenovirus encoding mutant human survivin (Ad-surv DCs). Immunization of mice with Ad-surv DCs resulted in generation of CD8 T cells recognizing multiple epitopes from mouse survivin. These responses provided significant antitumor effect against 3 different tumors EL-4 lymphoma, MC-38 carcinoma, and MethA sarcoma. Survivin-specific T-cells did not affect bone marrow hematopoietic progenitor cells and no autoimmune abnormalities were observed. However, as was the case with other tumor vaccines it provided only partial antitumor effect against established tumors. The existing paradigm suggests that generation of immune response against multiple tumor-associated antigens may provide a better antitumor effect. Here, we directly tested this hypothesis by combining vaccines targeting different tumor-associated proteins: survivin and p53. Despite the fact that combination of 2 vaccines generated potent antigen specific T-cell responses against both molecules they did not result in the improvement of antitumor effect in any of the tested experimental tumor models.

Altered recognition of antigen is a mechanism of CD8+ T cell tolerance in cancer

Antigen-specific CD8+ T-cell tolerance, induced by myeloid-derived suppressor cells (MDSCs), is one of the main mechanisms of tumor escape. Using in vivo models, we show here that MDSCs directly disrupt the binding of specific peptide-major histocompatibility complex (pMHC) dimers to CD8-expressing T cells through nitration of tyrosines in a T-cell receptor (TCR)-CD8 complex. This process makes CD8-expressing T cells unable to bind pMHC and to respond to the specific peptide, although they retain their ability to respond to nonspecific stimulation. Nitration of TCR-CD8 is induced by MDSCs through hyperproduction of reactive oxygen species and peroxynitrite during direct cell-cell contact. Molecular modeling suggests specific sites of nitration that might affect the conformational flexibility of TCR-CD8 and its interaction with pMHC. These data identify a previously unknown mechanism of T-cell tolerance in cancer that is also pertinent to many pathological conditions associated with accumulation of MDSCs.

Sequence-variant repeats of MUC1 show higher conformational flexibility, are less densely O-glycosylated and induce differential B lymphocyte responses

The human epithelial cancer mucin MUC1 is able to break tolerance and to induce humoral immune responses in healthy subjects and in cancer patients. We recently showed that clusters of sequence-variant repeats are interspersed in the repeat domain of MUC1 at high frequency, which should contribute to the structural and immunological features of the mucin. Here we elucidated the potential effects exerted by sequence-variant repeats on their O-glycosylation. Evidence from in vitro glycosylation with polypeptide N-acetylgalactosaminyltransferases GalNAc-T1 and GalNAc-T2 in concert with mass spectrometric analyses of in vivo glycosylated MUC1 probes from transiently transfected HEK293 cells indicated reduced glycosylation densities of repeats with three concerted replacements: AHGVTSAPESRPAPGSTAPA. The Pro to Ala replacement in STAPA exerts not only proximal effects on the ppGalNAc-T2 preferred site at -3 and -4, but also more distant effects on the ppGalNAc-T1 preferred site at -15 (TSAPESRPAPGSTAPA). We also examined the conformational changes of MUC1 glycopeptides induced by the concerted DT to ES replacements and revealed a higher conformational flexibility of ES/P peptides compared to DT/P peptides. Differences in conformational flexibilities and in O-glycosylation densities could underlie the observed differential humoral responses in humans. We were able to show that the natural immunoglobulin G (IgG) responses to the repeat domain of MUC1 in sera from nonmalignant control subjects are preferentially directed to variant repeat clusters. In contrast, the IgG response in patients with adenocarcinoma shifted to higher frequencies of preferential DTR peptide binding.

Full-length dominant-negative survivin for cancer immunotherapy

PURPOSE

The goal of this study is to investigate the possible utility of dendritic cells (DCs) transduced with the human full-length dominant-negative survivin for cancer immunotherapy.

EXPERIMENTAL DESIGN

Mononuclear cells were collected from HLA-A2-positive healthy volunteers and patients with prostate cancer. DCs were transduced with an adenoviral vector containing a full-length, dominant-negative survivin gene. After three rounds of stimulation, the T-cell response against three different survivin-derived HLA-A2-matching peptides was tested in IFN-gamma enzyme-linked immunospot and CTL assays.

RESULTS

Seven of eight healthy volunteers and cancer patients showed a significant response to at least two different survivin-derived epitopes in the enzyme-linked immunospot assay. One patient responded to only one peptide. All four healthy volunteers and two of three patients tested demonstrated a specific CTL response against T2 target cells loaded with one survivin-derived epitope. Two donors and two patients had a significant CTL response against two different epitopes. Significant cytotoxic activity was seen against HLA-A2-positive MCF-7 tumor cells that express survivin. That response was specific for survivin and was MHC class I restricted. Because survivin is expressed in CD34(+) hematopoietic progenitor cells (HPCs), we tested whether the antisurvivin CTLs can recognize normal HPCs. The incubation of survivin-specific CTLs with CD34(+) cells did not significantly decrease the colony-forming ability of HPCs.

CONCLUSIONS

DCs transduced with dominant-negative survivin induce potent survivin-specific CTL responses able to recognize and kill tumor cells. This response does not significantly affect HPCs. Thus, this study may provide rationale for immunotherapeutic clinical trials using a DC vaccine transduced with the dominant-negative survivin.

Tumor escape from immune response: mechanisms and targets of activity

Immune system plays an important role in control of tumor progression. Effective antitumor immune response depends on close interaction of several elements of immune system. They include antigen-presenting cells, different subsets of T cells, B cells and NK cells. However, tumor cells developed a number of mechanisms to escape recognition and elimination by immune system. In this review we will discuss these mechanisms and address possible approaches to correct them.

Flt3 ligand augmentation of T cell mitogenesis and expansion of type 1 effector/memory T cells

Herein we report mechanisms whereby Flt3 ligand (FL) augments steady state T cell activity in addition to the expansion of dendritic cells (DCs). We demonstrate that in vivo administration of FL increases the frequency and absolute number of effector/memory T cells and preferentially expands T cells that express a type-1 cytokine phenotype. In addition, FL enhances T cell proliferative responses to Concanavalin A that directly correlated with increased frequencies in effector/memory T cells and expansion of lymphoid-derived (type 1) DCs (DC1s). Together, these data demonstrate that mechanisms of FL-induced T cell regulation include not only the expansion of DC subsets, but also the preferential expansion of type 1 -effector/memory T cell populations, and suggest multiple mechanisms of action for FL as a vaccine adjuvant and as a therapeutic modality.

Immunization with wild-type p53 gene sequences coadministered with Flt3 ligand induces an antigen-specific type 1 T-cell response

We examined the ability of immunization with sequential adenovirus/plasmid DNA vectors expressing human wild-type p53 to stimulate a type 1 T-cell response and induce protection against challenge from a metastatic tumor that expresses mutated murine p53. We found that tumor protection and an antigen (Ag)-specific immune response were enhanced by prior injection of Flt3 ligand (Flt3L) at a dose and schedule that significantly increased dendritic cell (DC) number and frequency. Preliminary studies using enzyme-linked immunospot and Winn assays suggested that Ag-specific CD8 cells, with their significant increase in IFN-gamma-secreting activity (Tc1 cells), were responsible for the tumor protection. The delayed-type hypersensitivity response to p53 was increased in mice immunized with p53 alone or p53 and Flt3L compared with a negative control. In contrast, spleen cells from mice immunized with p53 and Flt3L exhibited a higher Ag-specific proliferative response than mice immunized with p53 alone. The frequencies of Ag-specific IFN-gamma and interleukin (IL)-4-secreting cells were determined using an enzyme-linked immunospot assay, which demonstrated that the frequency of IFN-gamma-secreting cells was significantly higher in mice immunized with p53 and Flt3L than in mice receiving Flt3L, excipient, or p53 treatment alone. In contrast, the frequency of IL-4-secreting cells did not differ significantly among these groups. We also observed an increased frequency of IL-12 and IFN-gamma-secreting cells (but not IL-4 or IL-10) in the spleens of mice immediately after 10 days of Flt3L treatment, which was also the day of p53 priming. This observation supports the likelihood that there are multiple mechanisms of Flt3L adjuvant activity, including expansion of DC and type 1 T-cell number. Overall, these results suggest that immunization with p53 genetic sequences after in vivo expansion of DC, using Flt3L, provides a useful strategy to induce p53-specific, and protective, type 1 T-cell responses.

Flt3 ligand and granulocyte-macrophage colony-stimulating factor preferentially expand and stimulate different dendritic and T-cell subsets

OBJECTIVE

Mechanisms of T-cell stimulation by Flt3 ligand (Flt3L) and granulocyte-macrophage colony-stimulating factor (GM-CSF) remain unclear. Herein, we compared the effects of Flt3L and GM-CSF on the expansion of dendritic cells (DC) and T-cell subsets and cytokine expression.

METHODS

Naïve and effector/memory T cells were analyzed by flow cytometry (FC). CD4(+) and CD8(+) T cells and CD11c(+)CD11b(dull/-)(DC1) and CD11c(+)CD11b(+) (DC2) subsets were isolated and the frequency of IFN-gamma-, IL-12- (type 1) and IL-4-, IL-10 (type 2)-producing cells and cytokine mRNA expression evaluated.

RESULTS

Flt3L expanded both DC1 and DC2 subsets with a significantly higher percentage and number of DC1 than DC2, while GM-CSF preferentially expanded the DC2 subset. Isolated DC1 from Flt3L-injected mice had significantly higher levels of IL-12 (p40) than IL-10, while the converse occurred with DC2. The numbers of naïve and memory T cells were elevated in mice that received Flt3L or GM-CSF. However, the number of memory CD4(+) and CD8(+) T cells was significantly increased in Flt3L as compared to GM-CSF cohorts. While GM-CSF increased the frequency of both type 1 and type 2 cytokine-producing cells, Flt3L significantly augmented the frequency of type 1 T cells.

CONCLUSIONS

In contrast to GM-CSF, Flt3L preferentially induces the expansion of type 1 T cells. The mechanism of Flt3L-induced T-cell stimulation is associated with the expansion of the IL-12 (p40)-producing DC1 and memory T cells.

Comparison of the hematopoietic activity of flt-3 ligand and granulocyte-macrophage colony-stimulating factor acting alone or in combination

The hematopoietic sequelae of intramuscular administration of flt-3 ligand (FL) and granulocyte-macrophage colony-stimulating factor (GM-CSF) alone, or in combination, were compared in BALB/c mice. Changes in hematopoiesis were measured in the marrow, spleen and blood using an in vitro colony-forming unit (CFU) assay and flow cytometrically (expression of CD34 and stem cell antigen (Sca)-1). FL administration was associated with a significant increase in the absolute number of CFU and CD34+ cells in the marrow and CFU, CD34+, Sca-1+, and CD34+ Sca-1+ cells in the spleen and blood. These data demonstrate that FL expands and mobilizes a range of hematopoietic progenitors. By comparison, GM-CSF administration was associated with a significant increase in the number of CFU in the spleen and a significant reduction in marrow CD34+, Sca-1+, and CD34+Sca-1+ cells. These data suggest that GM-CSF-driven expansion of CFU may be at the expense of more primitive cells. The pattern of progenitor cell expansion associated with FL + GM-CSF administration was similar to that of FL alone with the following exceptions. The numbers of spleen and blood CFU were significantly greater and the number of marrow CD34+Sca-1+ cells were significantly less, than with FL alone. These data suggest that co-administration of these cytokines may combine the expansion of the more primitive cell populations (associated with FL) with the expansion of the more mature CFU population (associated with GM-CSF) to yield a greater overall CFU expansion and elevation of CFU in the blood. However, increasing the expansion and mobilization of the relatively mature, rather than the more primitive, hematopoietic progenitors, may be of limited value as a mobilization strategy, if the goal is the expansion and isolation of increased numbers of "high-quality," primitive cells for transplantation.