CCR4 Blockade Diminishes Intratumoral Macrophage Recruitment and Augments Survival of Syngeneic Pancreatic Cancer-Bearing Mice

Pancreatic cancer is known for its tumor microenvironment (TME), which is rich in stromal and immune cells supporting cancer growth and therapy resistance. In particular, tumor-associated macrophages (TAMs) are known for their angiogenesis- and metastasis-promoting properties, which lead to the failure of conventional therapies for pancreatic cancer. Hence, treatment options targeting TAMs are needed. The C-C chemokine receptor type 4 (CCR4) is critical for immune cell recruitment into the TME, and in this paper we explore the effects of its genetic or immunotherapeutic blockade in pancreatic-cancer-bearing mice. Murine PDA6606 pancreatic cancer cells and murine peritoneal macrophages were used for in vitro migration assays. In vivo, a syngeneic, orthotropic pancreatic cancer model was established. Tumor growth and survival were monitored under prophylactic and therapeutic application of a CCR4 antagonist (AF-399/420/18025) in wildtype (CCR4^wt) and CCR4-knockout (CCR4^-/-) mice. Immune infiltration was monitored in tumor tissue sections and via flow cytometry of lysed tumors. PDA6606 cells induced less migration in CCR4^-/- than in CCR4^wt macrophages in vitro. Pancreatic TAM infiltration was higher, and survival was reduced in CCR4^wt mice compared to CCR4^-/- mice. Antagonizing CCR4 in wildtype mice revealed similar results as in CCR4^-/- mice without antagonization. Prophylactic CCR4 antagonist application in wildtype mice was more efficient than therapeutic antagonization. CCR4 seems to be critically involved in TAM generation and tumor progression in pancreatic cancer. CCR4 blockade may help prolong the relapse-free period after curative surgery in pancreatic cancer and improve prognosis.

Disseminated Intravascular Coagulation (DIC): Old player creates new perspectives on the polymicrobial sepsis model of CASP

BACKGROUND

Disseminated Intravascular Coagulation (DIC) is a life-threatening complication of sepsis. In surgical ICUs, DIC is frequently caused by abdominal sepsis, and the disarranged coagulation and complications often lead to death. The severity of sepsis is associated with a higher DIC score according to the parameters proposed by the International Society of Hemostasis and Thrombosis (ISTH) in 2001: platelet count, bleeding time (Quick), D-dimer, and fibrinogen. One problem in studying DIC is finding an adequate animal model that reflects the clinical situation of polymicrobial overwhelming infection.

AIMS AND METHODS

We investigated whether a well-established polymicrobial sepsis model of colon ascendens stent peritonitis (CASP) is suited to investigate the complexity of DIC. For this purpose, CASP-operated mice were examined 20 h after the operation with regard to coagulation parameters using cell counts, bleeding times, rotational thromboelastometry (ROTEM), ELISAs for D-dimer and fibrinogen, and platelet accumulation in affected organs via immunohistochemistry to see if the mice develop a coagulation disorder that meets the definition of DIC proposed by the ISTH 2001 consensus conference.

RESULTS

Herein, we showed that the CASP model is an all-encompassing animal model to analyze the complexity of systemic DIC in murine abdominal sepsis. There is highly reproducible thrombocytopenia, a significant prolongation of the bleeding time, and a loss of fibrinogen in plasma. We also observed microvascular thrombosis due to platelet accumulation in the microcirculation of the liver.

CONCLUSION

The CASP model seems superior to other artificial models, e.g., injecting substances, for inducing DIC. CASP is one of the best true-to-life models for analyzing the complexity of disseminated intravascular coagulation in polymicrobial sepsis.

Investigating the Association Between the Co-Occurrence of Behavioral Health Risk Factors and Sick Days in General Hospital Patients

Objectives: To investigate the co-occurrence of 4 behavioral health risk factors (BHRFs), namely tobacco smoking, alcohol at-risk drinking, physical inactivity and unhealthy diet and their association with sick days prior to hospitalization in general hospital patients.

Methods: Over 10 weeks (11/2020-04/2021), all 18-64-year-old patients admitted to internal medicine, general and trauma surgery, and otorhinolaryngology wards of a tertiary care hospital were systematically approached. Among 355 eligible patients, 278 (78.3%) participated, and 256 (72.1%) were analyzed. Three BHRF sum scores were determined, including current tobacco smoking, alcohol use, physical inactivity and 1 of 3 indicators of unhealthy diet. Associations between BHRF sum scores and sick days in the past 6 months were analyzed using multivariate zero-inflated negative binomial regressions.

Results: Sixty-two percent reported multiple BHRFs (≥2). The BHRF sum score was related to the number of sick days if any (p = 0.009) with insufficient vegetable and fruit intake as diet indicator.

Conclusion: The majority of patients disclosed multiple BHRFs. These were associated with sick days prior to admission. The findings support the need to implement interventions targeting multiple BHRFs in general hospitals.

Murine Macrophages Modulate Their Inflammatory Profile in Response to Gas Plasma-Inactivated Pancreatic Cancer Cells

Macrophages and immuno-modulation play a dominant role in the pathology of pancreatic cancer. Gas plasma is a technology recently suggested to demonstrate anticancer efficacy. To this end, two murine cell lines were employed to analyze the inflammatory consequences of plasma-treated pancreatic cancer cells (PDA) on macrophages using the kINPen plasma jet. Plasma treatment decreased the metabolic activity, viability, and migratory activity in an ROS- and treatment time-dependent manner in PDA cells in vitro. These results were confirmed in pancreatic tumors grown on chicken embryos in the TUM-CAM model (in ovo). PDA cells promote tumor-supporting M2 macrophage polarization and cluster formation. Plasma treatment of PDA cells abrogated this cluster formation with a mixed M1/M2 phenotype observed in such co-cultured macrophages. Multiplex chemokine and cytokine quantification showed a marked decrease of the neutrophil chemoattractant CXCL1, IL6, and the tumor growth supporting TGFβ and VEGF in plasma-treated compared to untreated co-culture settings. At the same time, macrophage-attractant CCL4 and MCP1 release were profoundly enhanced. These cellular and secretome data suggest that the plasma-inactivated PDA6606 cells modulate the inflammatory profile of murine RAW 264.7 macrophages favorably, which may support plasma cancer therapy.

Oxidation-Specific Epitopes (OSEs) Dominate the B Cell Response in Murine Polymicrobial Sepsis

In murine abdominal sepsis by colon ascendens stent peritonitis (CASP), a strong increase in serum IgM and IgG antibodies was observed, which reached maximum values 14 days following sepsis induction. The specificity of this antibody response was studied in serum and at the single cell level using a broad panel of bacterial, sepsis-unrelated as well as self-antigens. Whereas an antibacterial IgM/IgG response was rarely observed, studies at the single-cell level revealed that IgM antibodies, in particular, were largely polyreactive. Interestingly, at least 16% of the IgM mAbs and 20% of the IgG mAbs derived from post-septic mice showed specificity for oxidation-specific epitopes (OSEs), which are known targets of the innate/adaptive immune response. This identifies those self-antigens as the main target of B cell responses in sepsis.

Antibody Production in Murine Polymicrobial Sepsis-Kinetics and Key Players

Although antigen-specific priming of antibody responses is impaired during sepsis, there is nevertheless a strong increase in IgM and IgG serum concentrations. Using colon ascendens stent peritonitis (CASP), a mouse model of polymicrobial abdominal sepsis, we observed substantial increases in IgM as well as IgG of all subclasses, starting at day 3 and peaking 2 weeks after sepsis induction. The dominant source of antibody-secreting cells was by far the spleen, with a minor contribution of the mesenteric lymph nodes. Remarkably, sepsis induction in splenectomized mice did not change the dynamics of the serum IgM/IgG reaction, indicating that the marginal zone B cells, which almost exclusively reside in the spleen, are dispensable in such a setting. Hence, in systemic bacterial infection, the function of the spleen as dominant niche of antibody-producing cells can be compensated by extra-splenic B cell populations as well as other lymphoid organs. Depletion of CD4+ T cells did not affect the IgM response, while it impaired IgG generation of all subclasses with the exception of IgG3. Taken together, our data demonstrate that the robust class-switched antibody response in sepsis encompasses both T cell-dependent and -independent components.

Cold Physical Plasma-Treated Buffered Saline Solution as Effective Agent Against Pancreatic Cancer Cells

BACKGROUND

Cold physical plasma has been suggested as a new anticancer tool recently. However, direct use of plasma is limited to visible tumors and in some clinical situations, is not feasible. This includes repetitive treatment of peritoneal metastases, which commonly occur in advanced gastrointestinal cancer and in pancreatic cancer in particular. In case of diffuse intraperitoneal metastatic spread, Hyperthermic Intraperitoneal Intraoperative Chemotherapy (HIPEC) is used as a therapeutic approach. Plasma-treated solutions may combine non-toxic characteristics with the anticancer effects of HIPEC. Previous work has provided evidence for an anticancer efficacy of plasma-treated cell culture medium but the clinical relevance of such an approach is low due to its complex formulation and lack of medical accreditation.

OBJECTIVE

Plasma-treated Phosphate-Buffered Saline (PBS), which closely resembles medically certified solutions, was investigated for its cytotoxic effect on 2D monolayer murine pancreatic cancer cells in vitro.

METHODS

Toxicity studies of primary murine fibroblasts, PDA6606 murine pancreatic cancer cells, and COLO 357 human pancreatic cancer cells exposed to plasma-treated PBS were performed.

RESULTS

Plasma-treated PBS significantly decreased cancer cell metabolisms and proliferation whereas plasma-treated Dulbecco's Modified Eagle Medium had no effect. Moreover, tumor cell growth attenuation was significantly higher when compared to syngeneic primary murine fibroblasts. Both results were confirmed in a human pancreatic cancer cell line. Finally, plasma-treated PBS also decreased the size of pancreatic tumors in a three-dimensional manner, and induction of apoptosis was found to be responsible for all anticancer effects identified.

CONCLUSION

Plasma-treated PBS inhibited cell growth in 2D and 3D models of cancer. These results may help facilitate the development of new plasma-derived anticancer agent with clinical relevance in the future.

Physical plasma-treated saline promotes an immunogenic phenotype in CT26 colon cancer cells in vitro and in vivo

Metastatic colorectal cancer is the fourth most common cause of cancer death. Current options in palliation such as hyperthermic intraperitoneal chemotherapy (HIPEC) present severe side effects. Recent research efforts suggested the therapeutic use of oxidant-enriched liquid using cold physical plasma. To investigate a clinically accepted treatment regimen, we assessed the antitumor capacity of plasma-treated saline solution. In response to such liquid, CT26 murine colon cancer cells were readily oxidized and showed cell growth with subsequent apoptosis, cell cycle arrest, and upregulation of immunogenic cell death (ICD) markers in vitro. This was accompanied by marked morphological changes with re-arrangement of actin fibers and reduced motility. Induction of an epithelial-to-mesenchymal transition phenotype was not observed. Key results were confirmed in MC38 colon and PDA6606 pancreatic cancer cells. Compared to plasma-treated saline, hydrogen peroxide was inferiorly toxic in 3D tumor spheroids but of similar efficacy in 2D models. In vivo, plasma-treated saline decreased tumor burden in Balb/C mice. This was concomitant with elevated numbers of intratumoral macrophages and increased T cell activation following incubation with CT26 cells ex vivo. Being a potential adjuvant for HIPEC therapy, our results suggest oxidizing saline solutions to inactivate colon cancer cells while potentially stimulating antitumor immune responses.

Efficiency of Emulsified Particle-Associated Polyhexamethylenbiguanid-Hydrochlorid (Polihexanide) for Peritoneal Lavage in a Murine Sepsis Model

BACKGROUND

Peritoneal lavage is often used for peritonitis, however, the volume and type of lavage fluid varies. Saline or Ringer's solution are used most often and lavage is performed until the fluid is clear. However, at present there is no irrigation fluid for peritoneal lavage with residual antiseptic activity. Because the combination of aqueous polyhexamethylenbiguanid-hydrochlorid (PHMB) and egg phosphatidylcholine containing oil/water emulsions (Lipofundin^® MCT 20%, B. Braun AG, Melsungen, Germany) protect mammalian cells without neutralizing the antiseptic effect of PHMB, it seemed promising to investigate such human cell protecting, yet antibacterial combination for peritoneal lavage in a murine sepsis model.

METHODS

After induction of colon ascendens stent peritonitis (CASP) in mice, the foci were eradicated by re-laparotomy, followed by twofold lavage with 2 × 3 mL of the tested emulsion. The following lavage fluids were investigated blindly: 10% Lipofundin/0.05% PHMB, 100% Lipofundin, 0.05% PHMB, and 0.9% saline. After 24 hours the animals were euthanized and organs, blood, and lavage fluid were examined for cytokine levels (tumor necrosis factor [TNF]-α, interferon [IFN]-γ, interleukin [IL]-6, IL-10), liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], gamma-glutamyltransferase [gamma-GT], glutamate dehydrogenase [GLDH]), creatinine, and bacterial density.

RESULTS

Only the combination of Lipofundin/PHMB (n = 23) increased the survival rate. Compared with saline alone, PHMB alone decreased the survival rate. Twenty-four hours after induction of peritonitis, the lowest number of colony forming units (CFU) was observed after lavage with PHMB/Lipofundin in all examined organs, blood, and lavage fluid (p < 0.01). Alanine aminotransferase, AST, and creatinine levels were increased after lavage with PHMB compared with the other lavage fluids (p < 0.05).

CONCLUSIONS

Peritoneal lavage using 0.05% aqueous PHMB alone resulted in no survival benefit in a CASP murine model. The increase of liver enzymes and creatinine seem to be a toxic side effect of PHMB. However, an emulsion of 0.05% PHMB/10% Lipofundin decreased cytotoxicity while maintaining antiseptic efficiency. The advantage for survival was explained by decrease of bacterial load in organs, blood, and lavage fluid. The results provide a new option for the treatment of peritonitis using peritoneal lavage with the combination of PHMB/Lipofundin.

The MRI Sepsis Score: An Innovative Tool for the Evaluation of Septic Peritonitis in Mice Using 7-Tesla Small Animal MRI

BACKGROUND

Magnetic resonance imaging (MRI) techniques are rarely used in the context of abdominal sepsis and in sepsis research. This study investigates the impact of MRI for monitoring septic peritonitis in an animal model (colon ascendens stent-induced peritonitis, CASP). The CASP model closely mimics that of human disease and is highly standardized. The most frequently employed readout parameter in mouse CASP studies is prolonged or decreased rate of survival. Monitoring the progression of peritonitis via MRI could provide a helpful tool in the evaluation of severity. The use of alternative readout systems could very well reduce the number of research animals. Perspectively, clinical improvement after certain treatment could be classified.

METHODS

This study describes for the first time MRI findings following the induction of septic peritonitis in mice using the CASP model. Two sublethal groups of mice with septic peritonitis were investigated. Each had received one of two differing stent diameters in order to control the leakage of feces into the abdominal cavity. Each mouse served as its own control. Imaging and analyses were performed blinded. Gut diameters, stomach volume, abdominal organ wall diameters, and volume of the adrenal glands were measured. Serum corticosterone levels were detected using ELISA. Serum IL-6, TNF-α, IL-1β, and IL-10 levels were screened by cytometric bead array. Statistical analysis was performed using the Mann-Whitney U test for nonparametric probes and the Kruskal-Wallis and t tests.

RESULTS

Using a 7-tesla MRI scanner 24 and 48 h after induction of septic peritonitis, interenteric fluid, organ swelling of spleen and adrenal glands, as well as dilatation of the stomach were compared to nonseptic conditions. Swelling of adrenal glands resulted in an increased serum corticosterone level. In addition, the wall of the intestine bowel was thickened. Based upon these findings, an MRI score (MRI sepsis score, MSS) for abdominal sepsis in mice was established. Reduced stent sizes led to reduced severity of the abdominal sepsis, which could be reproduced in the MSS, which is described here for the first time.

CONCLUSIONS

Intraabdominal variations during septic peritonitis are detectable by MRI techniques. MRI methods should become a more important tool for the evaluation of abdominal peritonitis. MSS could provide an interesting tool for the evaluation of therapeutic strategies.

Further insights into the anti-PF4/heparin IgM immune response

Anti-platelet factor 4 (PF4)/heparin antibodies are not only the cause of heparin-induced thrombocytopenia but might also play a role in the antibacterial host defence. Recently, marginal zone (MZ) B cells were identified to be crucial for anti-PF4/heparin IgG antibody production in mice. Combining human studies and a murine model of polymicrobial sepsis we further characterised the far less investigated anti-PF4/heparin IgM immune response. We detected anti-PF4/heparin IgM antibodies in the sera of paediatric patients < 6 months of age after cardiac surgery and in sera of splenectomised mice subjected to polymicrobial sepsis. In addition, PF4/heparin-specific IgM B cells were not only found in murine spleen, but also in peritoneum and bone marrow upon in vitro stimulation. Together, this indicates involvement of additional B cell populations, as MZ B cells are not fully developed in humans until the second year of life and are restricted to the spleen in mice. Moreover, PF4/heparin-specific B cells were detected in human cord blood upon in vitro stimulation and PF4-/- mice produced anti-PF4/heparin IgM antibodies after polymicrobial sepsis. In conclusion, the anti-PF4/heparin IgM response is a potential innate immune reaction driven by a B cell population distinct from MZ B cells.