Fever-range hyperthermia improves the anti-apoptotic effect induced by low pH on human neutrophils promoting a proangiogenic profile

Lactic acid: a narrative review of a promoter of the liver cancer microenvironment

Background and Objective

Lactic acid is a metabolite of glycolysis produced in the body, and its production is thought to be a mechanism by which cancer cells evade immune surveillance. Immune evasion and metabolic changes are well established as basic hallmarks of cancer. Although lactate has long been considered a waste product, it is now generally recognized to be a versatile small-molecule chemical that plays an important part in the tumor microenvironment (TME), with increased lactate production linked to the development of human malignancies. Metabolism in liver cancer is redirected toward glycolysis, which enhances the production of metabolic compounds used by tumor cells to produce proteins, lipids, and nucleotides, enabling them to maintain high proliferation rates and to establish the TME. Dysregulation of metabolic activity in liver cancer may impair antitumor responses owing to the immunosuppressive activity of the lactate produced by anaerobic glycolytic rates in tumor cells. This review primarily explores the link connection between lactic acid and the TME; evaluates the role of lactic acid in the occurrence, metastasis, prognosis, and treatment of liver cancer. Additionally, it investigates the associated pathways as potential targets for liver cancer treatment.

Methods

Literature searches were conducted in PubMed, Web of Science, and Google Scholar, with the publication date of the most recent article included being January 2024. After eliminating duplicate articles and less relevant articles through titles and abstracts, we selected 113 articles for this review. We categorized references into two categories. One is to classify the content into lactate-related, liver cancer-related and tumor metabolism-related. The other is to classify the article types, which are divided into reviews, research articles and clinical trials. Additionally, we consulted the reference lists of the relevant articles to ensure coverage was comprehensive and unbiased.

Key Content and Findings

The connection between lactic acid and the TME has recently become an area of intense research interest, and many related articles have been published in this field. The main finding of this review is to summarize the proven link between lactate and the TME and its possible impact on the TME of liver cancer. And analyzed the potential of lactate in liver cancer treatment and prognosis prediction.

Conclusions

Lactate may be key to developing novel approaches in the future treatment of liver cancer. Related research on the combination of classic therapies and molecular targeted drugs may provide innovative medicines that more selectively regulate immune cell activity.

Temperature control in sepsis

Fever can be viewed as an adaptive response to infection. Temperature control in sepsis is aimed at preventing potential harms associated with high temperature (tachycardia, vasodilation, electrolyte and water loss) and therapeutic hypothermia may be aimed at slowing metabolic activities and protecting organs from inflammation. Although high fever (>39.5°C) control is usually performed in critically ill patients, available cohorts and randomized controlled trials do not support its use to improve sepsis prognosis. Finally, both spontaneous and therapeutic hypothermia are associated with poor outcomes in sepsis.

Immune evasion in esophageal squamous cell cancer: From the perspective of tumor microenvironment

Esophageal cancer (EC) is one of the most life-threatening malignancies worldwide. Esophageal squamous cell carcinoma (ESCC) is the dominant subtype, accounting for approximately 90% of new incident EC each year. Although multidisciplinary treatment strategies have advanced rapidly, patients with ESCC are often diagnosed at advanced stage and the long-term prognosis remains unsatisfactory. In recent decades, immunotherapy, such as immune checkpoint inhibitors (ICIs), tumor vaccines, and chimeric antigen receptor T-cell (CAR-T) therapy, has been successfully used in clinical practice as a novel therapy for treating tumors, bringing new hope to ESCC patients. However, only a small fraction of patients achieved clinical benefits due to primary or acquired resistance. Immune evasion plays a pivotal role in the initiation and progression of ESCC. Therefore, a thorough understanding of the mechanisms by which ESCC cells escape from anti-tumor immunity is necessary for a more effective multidisciplinary treatment strategy. It has been widely recognized that immune evasion is closely associated with the crosstalk between tumor cells and the tumor microenvironment (TME). TME is a dynamic complex and comprehensive system including not only cellular components but also non-cellular components, which influence hallmarks and fates of tumor cells from the outside. Novel immunotherapy targeting tumor-favorable TME represents a promising strategy to achieve better therapeutic responses for patients with ESCC. In this review, we provide an overview of immune evasion in ESCC, mainly focusing on the molecular mechanisms that underlie the role of TME in immune evasion of ESCC. In addition, we also discuss the challenges and opportunities of precision therapy for ESCC by targeting TME.

Ca2+ Signalling and Hypoxia/Acidic Tumour Microenvironment Interplay in Tumour Progression

Solid tumours are characterised by an altered microenvironment (TME) from the physicochemical point of view, displaying a highly hypoxic and acidic interstitial fluid. Hypoxia results from uncontrolled proliferation, aberrant vascularization and altered cancer cell metabolism. Tumour cellular apparatus adapts to hypoxia by altering its metabolism and behaviour, increasing its migratory and metastatic abilities by the acquisition of a mesenchymal phenotype and selection of aggressive tumour cell clones. Extracellular acidosis is considered a cancer hallmark, acting as a driver of cancer aggressiveness by promoting tumour metastasis and chemoresistance via the selection of more aggressive cell phenotypes, although the underlying mechanism is still not clear. In this context, Ca2+ channels represent good target candidates due to their ability to integrate signals from the TME. Ca2+ channels are pH and hypoxia sensors and alterations in Ca2+ homeostasis in cancer progression and vascularization have been extensively reported. In the present review, we present an up-to-date and critical view on Ca2+ permeable ion channels, with a major focus on TRPs, SOCs and PIEZO channels, which are modulated by tumour hypoxia and acidosis, as well as the consequent role of the altered Ca2+ signals on cancer progression hallmarks. We believe that a deeper comprehension of the Ca2+ signalling and acidic pH/hypoxia interplay will break new ground for the discovery of alternative and attractive therapeutic targets.

Extracellular pH Controls Chemotaxis of Neutrophil Granulocytes by Regulating Leukotriene B4 Production and Cdc42 Signaling

Neutrophil granulocytes are the first and robust responders to the chemotactic molecules released from an inflamed acidic tissue. The aim of this study was to elucidate the role of microenvironmental pH in neutrophil chemotaxis. To this end, we used neutrophils from male C57BL/6J mice and combined live cell imaging chemotaxis assays with measurements of the intracellular pH (pH_i) in varied extracellular pH (pH_e). Observational studies were complemented by biochemical analyses of leukotriene B₄ (LTB₄) production and activation of the Cdc42 Rho GTPase. Our data show that pH_i of neutrophils dose-dependently adapts to a given pH of the extracellular milieu. Neutrophil chemotaxis toward C5a has an optimum at pH_i ∼7.1, and its pH_i dependency is almost parallel to that of LTB₄ production. Consequently, a shallow pH_e gradient, resembling that encountered by neutrophils during extravasation from a blood vessel (pH ∼7.4) into the interstitium (pH ∼7.2), favors chemotaxis of stimulated neutrophils. Lowering pH_e below pH 6.8, predominantly affects neutrophil chemotaxis, although the velocity is largely maintained. Inhibition of the Na⁺/H⁺ exchanger 1 (NHE1) with cariporide drastically attenuates neutrophil chemotaxis at the optimal pH_i irrespective of the high LTB₄ production. Neutrophil migration and chemotaxis are almost completely abrogated by inhibiting LTB₄ production or blocking its receptor (BLT1). The abundance of the active GTP-bound form of Cdc42 is strongly reduced by NHE1 inhibition or pH_e 6.5. In conclusion, we propose that the pH dependence of neutrophil chemotaxis toward C5a is caused by a pH_i-dependent production of LTB₄ and activation of Cdc42. Moreover, it requires the activity of NHE1.

Role of proton-activated G protein-coupled receptors in pathophysiology

Local acidification is a common feature of many disease processes such as inflammation, infarction, or solid tumor growth. Acidic pH is not merely a sequelae of disease but contributes to recruitment and regulation of immune cells, modifies metabolism of parenchymal, immune and tumor cells, modulates fibrosis, vascular permeability, oxygen availability and consumption, invasiveness of tumor cells, and impacts on cell survival. Thus, multiple pH-sensing mechanisms must exist in cells involved in these processes. These pH-sensors play important roles in normal physiology and pathophysiology, and hence might be attractive targets for pharmacological interventions. Among the pH-sensing mechanisms, OGR1 (GPR68), GPR4 (GPR4), and TDAG8 (GPR65) have emerged as important molecules. These G protein-coupled receptors are widely expressed, are upregulated in inflammation and tumors, sense changes in extracellular pH in the range between pH 8 and 6, and are involved in modulating key processes in inflammation, tumor biology, and fibrosis. This review discusses key features of these receptors and highlights important disease states and pathways affected by their activity.

Effects of pH alterations on stress- and aging-induced protein phase separation

Upon stress challenges, proteins/RNAs undergo liquid–liquid phase separation (LLPS) to fine-tune cell physiology and metabolism to help cells adapt to adverse environments. The formation of LLPS has been recently linked with intracellular pH, and maintaining proper intracellular pH homeostasis is known to be essential for the survival of organisms. However, organisms are constantly exposed to diverse stresses, which are accompanied by alterations in the intracellular pH. Aging processes and human diseases are also intimately linked with intracellular pH alterations. In this review, we summarize stress-, aging-, and cancer-associated pH changes together with the mechanisms by which cells regulate cytosolic pH homeostasis. How critical cell components undergo LLPS in response to pH alterations is also discussed, along with the functional roles of intracellular pH fluctuation in the regulation of LLPS. Further studies investigating the interplay of pH with other stressors in LLPS regulation and identifying protein responses to different pH levels will provide an in-depth understanding of the mechanisms underlying pH-driven LLPS in cell adaptation. Moreover, deciphering aging and disease-associated pH changes that influence LLPS condensate formation could lead to a deeper understanding of the functional roles of biomolecular condensates in aging and aging-related diseases.

Extracellular acidosis stimulates breast cancer cell motility through aryl hydrocarbon receptor and c-Src kinase activation

A reduction in extracellular pH (pHe) is a characteristic of most malignant tumors. The aryl hydrocarbon receptor (AhR) is a transcription factor localized in a cytosolic complex with c-Src, which allows it to trigger non-genomic effects through c-Src. Considering that the slightly acidic tumor microenvironment promotes breast cancer progression in a similar way to the AhR/c-Src axis, our aim was to evaluate whether this pathway could be activated by low pHe. We examined the effect of pHe 6.5 on AhR/c-Src axis using two breast cancer cell lines (MDA-MB-231 and LM3) and mammary epithelial cells (NMuMG) and found that acidosis increased c-Src phosphorylation only in tumor cells. Moreover, the presence of AhR inhibitors prevented c-Src activation. Low pHe reduced intracellular pH (pHi), while amiloride treatment, which is known to reduce pHi, induced c-Src phosphorylation through AhR. Analyses were conducted on cell migration and metalloproteases (MMP)-2 and -9 activities, with results showing an acidosis-induced increase in MDA-MB-231 and LM3 cell migration and MMP-9 activity, but no changes in NMuMG cells. Moreover, all these effects were blocked by AhR and c-Src inhibitors. In conclusion, acidosis stimulates the AhR/c-Src axis only in breast cancer cells, increasing cell migration and MMP-9 activity. Although the AhR activation mechanism still remains elusive, a reduction in pHi may be thought to be involved. These findings suggest a critical role for the AhR/c-Src axis in breast tumor progression stimulated by an acidic microenvironment. This article is protected by copyright. All rights reserved.

The underlying molecular mechanism of intratumoral radiofrequency hyperthermia-enhanced chemotherapy of pancreatic cancer

Background

To investigate the underlying molecular mechanisms of radiofrequency hyperthermia (RFH)-enhanced direct chemotherapy of pancreatic cancers.

Method

Rat ductal PaCa cell line DSL-6A/C1 and orthotopic pancreatic cancers of Lewis rats were divided into four study groups with various treatments: i) phosphate-buffered saline (PBS) as a control; ii) RFH alone; iii) intratumoral chemotherapy alone (gemcitabine); and (iv) combination therapy of gemcitabine plus intratumoral RFH at 42 ​°C for 30 ​min. In the in-vitro confirmation experiments, the viability and apoptosis of DSL-6A/C1 cells in each treatment group were evaluated using cell live/dead staining, flow cytometry, and Western blot. In the in vivo validation experiments, related proteins were evaluated by immunohistochemistry (IHC) staining of tumors.

Results

Of the in-vitro experiments, the lowest cell viability and more apoptotic cells were shown in the group with combination therapy compared to other treatments. Western blot data showed elevated Bax/Bcl-2, Caspase-3, and HSP70 expressions in DSL cells with combination therapy, compared to other treatments. Of the in vivo experiments, IHC staining detected the significantly increased expressions of HSP70, IL-1β, TNF-ɑ, Bax, and Caspase-3 in pancreatic cancer tissues of the animal group treated by combination therapy of gemcitabine with RFH.

Conclusion

Molecular imaging-guided interventional RFH can significantly enhance the chemotherapeutic effect on pancreatic cancers via potential molecular mechanisms of up-regulating Bax/caspase-3-dependent apoptosis pathways.

Anti-disialoganglioside antibody internalization by neuroblastoma cells as a mechanism of immunotherapy resistance

Neuroblastoma (NBL) accounts for a disproportionate number of deaths among childhood malignancies despite intensive multimodal therapy that includes antibody targeting disialoganglioside GD2, a NBL antigen. Unfortunately, resistance to anti-GD2 immunotherapy is frequent and we aimed to investigate mechanisms of resistance in NBL. GD2 expression was quantified by flow cytometry and anti-GD2 antibody internalization was measured using real-time microscopy in 20 human NBL cell lines. Neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) assays were performed on a subset of the cell lines (n = 12), and results were correlated with GD2 expression and antibody internalization. GD2 was expressed on 19 of 20 NBL cell lines at variable levels, and neutrophil-mediated ADCC was observed only in GD2-expressing cell lines. We found no correlation between level of GD2 expression and sensitivity to neutrophil-mediated ADCC, suggesting that GD2 expression of many cell lines was above a threshold required for maximal ADCC, such that expression level could not be used to predict subsequent cytotoxicity. Instead, anti-GD2 antibody internalization, a process that occurred universally but differentially across GD2-expressing NBL cell lines, was inversely correlated with ADCC. Treatment with endocytosis inhibitors EIPA, chlorpromazine, MBCD, and cytochalasin-D showed potential to inhibit antibody internalization; however, only MBCD resulted in significantly increased sensitivity to neutrophil-mediated ADCC in 4 of 4 cell lines in vitro. Our data suggest that antibody internalization may represent a novel mechanism of immunotherapy escape by NBL and provide proof-of-principle that targeting pathways involved in antibody internalization may improve the efficacy of anti-GD2 immunotherapies.

Fenton/Fenton-like metal-based nanomaterials combine with oxidase for synergistic tumor therapy

Chemodynamic therapy (CDT) catalyzed by transition metal and starvation therapy catalyzed by intracellular metabolite oxidases are both classic tumor treatments based on nanocatalysts. CDT monotherapy has limitations including low catalytic efficiency of metal ions and insufficient endogenous hydrogen peroxide (H₂O₂). Also, single starvation therapy shows limited ability on resisting tumors. The “metal-oxidase” cascade catalytic system is to introduce intracellular metabolite oxidases into the metal-based nanoplatform, which perfectly solves the shortcomings of the above-mentioned monotherapiesIn this system, oxidases can not only consume tumor nutrients to produce a “starvation effect”, but also provide CDT with sufficient H₂O₂ and a suitable acidic environment, which further promote synergy between CDT and starvation therapy, leading to enhanced antitumor effects. More importantly, the “metal-oxidase” system can be combined with other antitumor therapies (such as photothermal therapy, hypoxia-activated drug therapy, chemotherapy, and immunotherapy) to maximize their antitumor effects. In addition, both metal-based nanoparticles and oxidases can activate tumor immunity through multiple pathways, so the combination of the “metal-oxidase” system with immunotherapy has a powerful synergistic effect. This article firstly introduced the metals which induce CDT and the oxidases which induce starvation therapy and then described the “metal-oxidase” cascade catalytic system in detail. Moreover, we highlight the application of the “metal-oxidase” system in combination with numerous antitumor therapies, especially in combination with immunotherapy, expecting to provide new ideas for tumor treatment.

Visfatin Exerts Immunotherapeutic Effects in Lipopolysaccharide-Induced Acute Lung Injury in Murine Model

Visfatin acts as a significant regulator of inflammatory cytokines. However, the immunological response and therapeutic effects of visfatin under bacterial stress in murine lung tissue are still not clear. To investigate the role of visfatin on lipopolysaccharide (LPS)-induced acute lung injury (ALI), thirty Kunming mice were divided into Saline, LPS, and LPS + visfatin groups. After routine blood examination, the effects of visfatin on inflammatory cytokines, lung tissue structure, and expression of inflammatory mediators were explored through hematoxylin-eosin (H&E), Masson and immunohistochemical staining, quantitative polymerase chain reaction (Q-PCR), and Western blotting. Compared with the Saline group, neutrophil percentage, peripheral blood neutrophil count, and the ratio of lymphocyte count (NLR) were upregulated in LPS group. Moreover, Masson staining showed alterations in lung tissue structure; the mRNA level of different cytokines (IL-6, IL-1β, TNF-α, IL-10, TLR4, IFN-γ) was upregulated; and the protein expression of interleukin (IL)-6, myeloperoxidase (MPO), and transforming growth factor-β1 (TGF-β) was significantly (p < 0.05) different in LPS group. Compared with LPS group, neutrophil percentage significantly decreased (p < 0.01), the numbers of lymphocytes significantly (p < 0.05) increased, NLR decreased, Masson staining of the lung was extremely different (p < 0.01), the structure of the lung was slightly damaged, and the myeloperoxidase values of lung showed no differences in LPS + visfatin. Hence, visfatin inhibits the lung inflammation induced by ALI. During the ALI, visfatin acts by decreasing NLR, downregulated the expression of MPO, enhanced antioxidant capacity, and regulated the inflammatory factors IL-1β, IL-6, IL-10, and TNF-α to reduce the lung injury.

Lactic Acid and an Acidic Tumor Microenvironment suppress Anticancer Immunity

Immune evasion and altered metabolism, where glucose utilization is diverted to increased lactic acid production, are two fundamental hallmarks of cancer. Although lactic acid has long been considered a waste product of this alteration, it is now well accepted that increased lactic acid production and the resultant acidification of the tumor microenvironment (TME) promotes multiple critical oncogenic processes including angiogenesis, tissue invasion/metastasis, and drug resistance. We and others have hypothesized that excess lactic acid in the TME is responsible for suppressing anticancer immunity. Recent studies support this hypothesis and provide mechanistic evidence explaining how lactic acid and the acidic TME impede immune cell functions. In this review, we consider lactic acid’s role as a critical immunoregulatory molecule involved in suppressing immune effector cell proliferation and inducing immune cell de-differentiation. This results in the inhibition of antitumor immune responses and the activation of potent, negative regulators of innate and adaptive immune cells. We also consider the role of an acidic TME in suppressing anticancer immunity. Finally, we provide insights to help translate this new knowledge into impactful anticancer immune therapies.

Transient intracellular acidification regulates the core transcriptional heat shock response

Heat shock induces a conserved transcriptional program regulated by heat shock factor 1 (Hsf1) in eukaryotic cells. Activation of this heat shock response is triggered by heat-induced misfolding of newly synthesized polypeptides, and so has been thought to depend on ongoing protein synthesis. Here, using the budding yeast Saccharomyces cerevisiae, we report the discovery that Hsf1 can be robustly activated when protein synthesis is inhibited, so long as cells undergo cytosolic acidification. Heat shock has long been known to cause transient intracellular acidification which, for reasons which have remained unclear, is associated with increased stress resistance in eukaryotes. We demonstrate that acidification is required for heat shock response induction in translationally inhibited cells, and specifically affects Hsf1 activation. Physiological heat-triggered acidification also increases population fitness and promotes cell cycle reentry following heat shock. Our results uncover a previously unknown adaptive dimension of the well-studied eukaryotic heat shock response.

What Is the Evolutionary Fingerprint in Neutrophil Granulocytes?

Over the years of evolution, thousands of different animal species have evolved. All these species require an immune system to defend themselves against invading pathogens. Nevertheless, the immune systems of different species are obviously counteracting against the same pathogen with different efficiency. Therefore, the question arises if the process that was leading to the clades of vertebrates in the animal kingdom-namely mammals, birds, amphibians, reptiles, and fish-was also leading to different functions of immune cells. One cell type of the innate immune system that is transmigrating as first line of defense in infected tissue and counteracts against pathogens is the neutrophil granulocyte. During the host-pathogen interaction they can undergo phagocytosis, apoptosis, degranulation, and form neutrophil extracellular traps (NETs). In this review, we summarize a wide spectrum of information about neutrophils in humans and animals, with a focus on vertebrates. Special attention is kept on the development, morphology, composition, and functions of these cells, but also on dysfunctions and options for cell culture or storage.

Metabolic Traits in Cutaneous Melanoma

Tumor microenvironment is a network of complex cellular and molecular systems where cells will gain specific phenotypes and specific functions that would drive tumorigenesis. In skin cancers, tumor microenvironment is characterized by tumor infiltrating immune cells that sustain immune suppression, mainly lymphocytes. Melanoma cellular heterogeneity can be described on genetic, proteomic, transcriptomic and metabolomic levels. Melanoma cells display a metabolic reprogramming triggered by both genetic alterations and adaptation to a microenvironment that lacks nutrients and oxygen supply. Tumor cells present clear metabolic adaptations and identifying deregulated glycolysis pathway could offer new therapy targets. Moreover, the immune cells (T lymphocytes, macrophages, NK cells, neutrophils and so on) that infiltrate melanoma tumors have metabolic particularities that, upon interaction within tumor microenvironment, would favor tumorigenesis. Analyzing both tumor cell metabolism and the metabolic outline of immune cells can offer innovative insights in new therapy targets and cancer therapeutical approaches. In addition to already approved immune- and targeted therapy in melanoma, approaching metabolic check-points could improve therapy efficacy and hinder resistance to therapy.

Neutrophils undergo switch of apoptosis to NETosis during murine fatty liver injury via S1P receptor 2 signaling

Inappropriate neutrophil infiltration and subsequent neutrophil extracellular trap (NET) formation have been confirmed to be involved in chronic inflammatory conditions. Fatty liver disease is an increasingly severe health problem worldwide and currently considered the most common cause of chronic liver disease. Sphingosine 1-phosphate (S1P), a product of membrane sphingolipid metabolism, regulates vital physiological and pathological actions by inducing infiltration and activation of various cell types through S1P receptors (S1PRs). Here, we seek to determine the S1PR-mediated effects on neutrophil activation during chronic liver inflammation. In this study, NETs are detected in the early stage of methionine-choline-deficient and a high-fat (MCDHF) diet-induced liver injury. NET depletion by deoxyribonuclease I intraperitoneal injection significantly protects liver from MCDHF-induced liver injury in vivo. Meanwhile, we show that levels of myeloperoxidase-DNA complex (NET marker) in the serum present positive correlation with sphingosine kinase1 (S1P rate-limiting enzyme) messenger RNA expression or S1P levels in the injured liver of MCDHF-fed mice. In vitro, S1PR₂ participates in the redirection of neutrophil apoptosis to NETosis via Gα_i/o, extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, and reactive oxygen species signaling pathways. Moreover, S1PR₂ knockdown in MCDHF-fed mice by S1PR₂-siRNA intravenous injection significantly inhibits NET formation in damaged liver tissue and then alleviates hepatic inflammation and fibrosis. Conclusion: In the early stage of fatty liver disease, S1PR₂-mediated neutrophil activation plays an important role in the evolvement of liver injury.

Short-Term Fever-Range Hyperthermia Accelerates NETosis and Reduces Pro-inflammatory Cytokine Secretion by Human Neutrophils

Fever is a hallmark of infections and inflammatory diseases, represented by an increase of 1-4°C in core body temperature. Fever-range hyperthermia (FRH) has been shown to increase neutrophil recruitment to local sites of infection. Here, we evaluated the impact of a short period (1 h) of FRH (STFRH) on pro-inflammatory and bactericidal human neutrophil functions. STFRH did not affect neutrophil spontaneous apoptosis but reverted the lipopolysaccharide (LPS)-induced anti-apoptotic effect compared with that under normothermic conditions. Furthermore, STFRH accelerated phorbol myristate acetate (PMA)-induced NETosis evaluated either by the nuclear DNA decondensation at 2 h post-stimulation or by the increase in extracellular DNA that colocalized with myeloperoxidase (MPO) at 4 h post-stimulation. Increased NETosis upon STFRH was associated with an increase in reactive oxygen species (ROS) production but not in autophagy levels. STFRH also increased NETosis in response to Pseudomonas aeruginosa challenge but moderately reduced its phagocytosis. However, these STFRH-induced effects did not influence the ability of neutrophils to kill bacteria after 4 h of co-culture. STFRH also significantly reduced neutrophil capacity to release the pro-inflammatory cytokines chemokine (C-X-C motif) ligand 8/interleukin 8 (CXCL8/IL-8) and IL-1β in response to LPS and P. aeruginosa challenge. Altogether, these results indicate that a short and mild hyperthermal period is enough to modulate neutrophil responses to bacterial encounter. They also suggest that fever spikes during bacterial infections might lead neutrophils to trigger an emergency response promoting neutrophil extracellular trap (NET) formation to ensnare bacteria in order to wall off the infection and to reduce their release of pro-inflammatory cytokines in order to limit the inflammatory response.

Unravelling the Interplay between Extracellular Acidosis and Immune Cells

The development of an acidic tissue environment is a hallmark of a variety of inflammatory processes and solid tumors. However, little attention has been paid so far to analyze the influence exerted by extracellular pH on the immune response. Tissue acidosis (pH 6.0 to 7.0) is usually associated with the course of infectious processes in peripheral tissues. Moreover, it represents a prominent feature of solid tumors. In fact, values of pH ranging from 5.7 to 7.0 are usually found in a number of solid tumors such as breast cancer, brain tumors, sarcomas, malignant melanoma, squamous cell carcinomas, and adenocarcinomas. Both the innate and adaptive arms of the immune response appear to be finely regulated by extracellular acidosis in the range of pH values found at inflammatory sites and tumors. Low pH has been shown to delay neutrophil apoptosis, promoting their differentiation into a proangiogenic profile. Acting on monocytes and macrophages, it induces the activation of the inflammasome and the production of IL-1β, while the exposure of conventional dendritic cells to low pH promotes the acquisition of a mature phenotype. Overall, these observations suggest that high concentrations of protons could be recognized by innate immune cells as a danger-associated molecular pattern (DAMP). On the other hand, by acting on T lymphocytes, low pH has been shown to suppress the cytotoxic response mediated by CD8+ T cells as well as the production of IFN-γ by TH1 cells. Interestingly, modulation of tumor microenvironment acidity has been shown to be able not only to reverse anergy in human and mouse tumor-infiltrating T lymphocytes but also to improve the antitumor immune response induced by checkpoint inhibitors. Here, we provide an integrated view of the influence exerted by low pH on immune cells and discuss its implications in the immune response against infectious agents and tumor cells.

Laser immunotherapy for cutaneous squamous cell carcinoma with optimal thermal effects to enhance tumour immunogenicity

BACKGROUND

Laser immunotherapy is a new anti-cancer therapy combining photothermal therapy and immunostimulation. It can eliminate the tumours by damaging tumour cells directly and promoting the release of damage-associated molecular patterns (DAMPs) to enhance tumour immunogenicity. The aim of this study was to investigate the thermal effects of laser immunotherapy and to evaluate the effectiveness and safety of laser immunotherapy for cutaneous squamous cell carcinoma (cSCC).

METHODS

The cell viability and the DAMPs productions of heat-treated cSCC A431 cells in different temperatures were investigated. Laser immunotherapy with the optimal thermal effect for DAMPs production was performed on SKH-1 mice bearing ultraviolet-induced cSCC and a patient suffering from a large refractory cSCC.

RESULTS

The temperature in the range of 45-50 °C killing half of A431 cells had an optimal thermal effect for the productions of DAMPs. The thermal effect could be further enhanced by local application of imiquimod, an immunoadjuvant. Laser immunotherapy eliminated most tumours and improved the survival rate of the ultraviolet-induced cSCC-bearing SKH-1 mice (p < 0.05). The patient with cSCC treated by laser immunotherapy experienced a significant tumour reduction after laser immunotherapy increased the amounts of infiltrating lymphocytes in the tumour. No obviously adverse effect was observed in the mice experiment or in the clinical application.

CONCLUSIONS

Our results strongly indicate that laser immunotherapy with optimal thermal effects is an effective and safe treatment modality for cSCC.

Sepsis Induces a Dysregulated Neutrophil Phenotype That Is Associated with Increased Mortality

Background

Neutrophil dysfunction in sepsis has been implicated in the pathogenesis of multiorgan failure; however, the role of neutrophil extracellular traps (NETs) remains uncertain. We aimed to determine the sequential changes in ex vivo NETosis and its relationship with mortality in patients with sepsis and severe sepsis.

Methods

This was a prospective observational cohort study enrolling 21 healthy age-matched controls and 39 sepsis and 60 severe sepsis patients from acute admissions to two UK hospitals. Patients had sequential bloods for the ex vivo assessment of NETosis in response to phorbol-myristate acetate (PMA) using a fluorometric technique and chemotaxis using time-lapse video microscopy. Continuous data was tested for normality, with appropriate parametric and nonparametric tests, whilst categorical data was analysed using a chi-squared test. Correlations were performed using Spearman's rho.

Results

Ex vivo NETosis was reduced in patients with severe sepsis, compared to patients with sepsis and controls (p = 0.002). PMA NETosis from patients with septic shock was reduced further (p < 0.001) compared to controls. The degree of metabolic acidosis correlated with reduced NETosis (p < 0.001), and this was replicated when neutrophils from healthy donors were incubated in acidotic media. Reduced NETosis at baseline was associated with an increased 30-day (p = 0.002) and 90-day mortality (p = 0.014) in sepsis patients. These findings were accompanied by defects in neutrophil migration and delayed apoptosis. Resolution of sepsis was not associated with the return to baseline levels of NETosis or migration.

Conclusions

Sepsis induces significant changes in neutrophil function with the degree of dysfunction corresponding to the severity of the septic insult which persists beyond physiological recovery from sepsis. The changes induced lead to the failure to effectively contain and eliminate the invading pathogens and contribute to sepsis-induced immunosuppression. For the first time, we demonstrate that reduced ex vivo NETosis is associated with poorer outcomes from sepsis.

Hierarchical Microplates as Drug Depots with Controlled Geometry, Rigidity, and Therapeutic Efficacy

A variety of microparticles have been proposed for the sustained and localized delivery of drugs with the objective of increasing therapeutic indexes by circumventing filtering organs and biological barriers. Yet, the geometrical, mechanical, and therapeutic properties of such microparticles cannot be simultaneously and independently tailored during the fabrication process to optimize their performance. In this work, a top-down approach is employed to realize micron-sized polymeric particles, called microplates (μPLs), for the sustained release of therapeutic agents. μPLs are square hydrogel particles, with an edge length of 20 μm and a height of 5 μm, made out of poly(lactic- co-glycolic acid) (PLGA). During the synthesis process, the μPL Young's modulus can be varied from 0.6 to 5 MPa by changing the PLGA amounts from 1 to 7.5 mg, without affecting the μPL geometry while matching the properties of the surrounding tissue. Within the porous μPL matrix, different classes of therapeutic payloads can be incorporated including molecular agents, such as anti-inflammatory dexamethasone (DEX), and nanoparticles containing imaging and therapeutic molecules themselves, thus originating a truly hierarchical platform. As a proof of principle, μPLs are loaded with free DEX and 200 nm spherical polymeric nanoparticles, carrying DEX molecules (DEX-SPNs). Electron and fluorescent confocal microscopy analyses document the uniform distribution and stability of molecular and nanoagents within the μPL matrix. This multiscale, hierarchical microparticle releases DEX for at least 10 days. The inclusion of DEX-SPNs serves to minimize the initial burst release and modulate the diffusion of DEX molecules out of the μPL matrix. The biopharmacological and therapeutic properties together with the fine tuning of geometry and mechanical stiffness make μPLs a unique polymeric depot for the potential treatment of cancer, cardiovascular, and chronic, inflammatory diseases.