The granulocyte-macrophage colony-stimulating factor receptor: linking its structure to cell signaling and its role in disease

Bound polyphenols in insoluble dietary fiber of navel orange peel modulate LPS-induced intestinal-like co-culture inflammation through CSF2-mediated NF-κB/JAK-STAT pathway

Our laboratory previously extracted bound polyphenols (BPP) in insoluble dietary fiber from navel orange peel (NOP-IDF), and the aim of this study was to investigate the anti-inflammatory activity and potential molecular mechanisms of BPP by establishing an LPS-induced intestinal-like Caco-2/RAW264.7 co-culture inflammation model. The results demonstrated that BPP reduced the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), as well as the production of pro-inflammatory cytokines, nitric oxide (NO), and reactive oxidative species (ROS) during the inflammatory damage process. Furthermore, BPP alleviated the lipopolysaccharides (LPS)-induced intestinal barrier damage by attenuating the decrease in trans-epithelial electrical resistance (TEER), diamine oxidase (DAO) activity, and intestinal alkaline phosphatase (IAP) activity, as well as the downregulation of ZO-1, Occludin, and Claudin-1 protein expression levels. RNA-seq results on RAW264.7 cells in the co-culture model showed that the NF-κB and JAK-STAT pathways belonged to the most significantly affected signaling pathways in the KEGG analysis, and western blot confirmed that they are essential for the role of BPP in intestinal inflammation. Additionally, overexpression of the granulocyte-macrophage colony-stimulating factor (CSF2) gene triggered abnormal activation of the NF-κB and JAK-STAT pathways and high-level expression of inflammatory factors, while BPP effectively improved this phenomenon. The above results suggested that BPP could inhibit intestinal inflammatory injury and protect intestinal barrier integrity through CSF2-mediated NF-κB and JAK-STAT pathways.

Combination Immunotherapy of Oncolytic Flu-Vectored Virus and Programmed Cell Death 1 Blockade Enhances Antitumor Activity in Hepatocellular Carcinoma

Oncolytic viruses (OVs) are appealing anti-tumor agents. But it is limited in its effectiveness. In this study, we used combination therapy with immune checkpoint inhibitor to enhance the antitumor efficacy of OVs. Using reverse genetics technology, we rescued an oncolytic influenza virus with the name delNS1-GM-CSF from the virus. After identifying the hemagglutination and 50% tissue culture infectivedose (TCID50) of delNS1-GM-CSF, it was purified, and the viral morphology was observed under electron microscopy. Reverse transcription quantitative-polymerase chain reaction (RT-qPCR) was used to identify the level of GM-CSF expression in delNS1-GM-CSF, and the GM-CSF expression level was determined after infection with delNS1-GM-CSF by enzyme linked immunosorbent assay (ELISA). To study the tumor-killing effect of delNS1-GM-CSF, we utilized the hepatocellular carcinoma (HCC) tumor-bearing mouse model. To examine signaling pathways, we performed transcriptome sequencing on mouse tumor tissue and applied western blotting to confirm the results. Changes in T-cell infiltration in HCC tumors following treatment were analyzed using flow cytometry and immunohistochemistry. DelNS1-GM-CSF can target and kill HCCs without damaging normal hepatocytes. DelNS1-GM-CSF combined with programmed cell death 1 blockade therapy enhanced anti-tumor effects and significantly improved mouse survival. Further, we found that combination therapy had an antitumor impact via the janus kinase-signal transducer and activator of transcription (JAK2-STAT3) pathway as well as activated CD4+ and CD8+T cells. Interestingly, combined therapy also showed promising efficacy in distant tumors. DelNS1-GM-CSF is well targeted. Mechanistic investigation revealed that it functions through the JAK2-STAT3 pathway. Combination immunotherapies expected to be a novel strategy for HCC immunotherapy.

Granulocyte-Macrophage Colony-Stimulating Factor in Combination With Chemoradiation for Recurrent or Metastatic Cervical Cancer

Recurrent or metastatic cervical cancer carries a bleak prognosis and presents a formidable challenge in terms of treatment. Granulocyte-macrophage colony-stimulating factor (GM-CSF) increases the body's immune response by enhancing antigen presentation, which has been rarely reported in recurrent or metastatic cervical cancer. A 44-year-old woman presented to the hospital with vaginal bleeding four years after radical hysterectomy for stage IB2 squamous cell carcinoma (SCC) of the cervix (grade II-III). Gynecological examination and imaging revealed a vaginal mass, and the biopsy confirmed the recurrence of grade III SCC. The patient was treated with chemoradiation (CRT) combined with immunoadjuvant GM-CSF and achieved complete remission and a progression-free survival of two years.

Sargramostim for Prophylactic Management of Gastrointestinal Immune-Related Adverse Events of Immune Checkpoint Inhibitor Therapy for Cancer

Immune checkpoint inhibitor (ICI) therapy improves outcomes in several cancers. Unfortunately, many patients experience grade 3-4 treatment-related adverse events, including gastrointestinal (GI) toxicities which are common. These GI immune-related adverse events (irAEs) induced by ICIs present significant clinical challenges, require prompt intervention, and result in treatment delays or discontinuations. The treatment for these potentially severe and even fatal GI irAEs which include enterocolitis, severe diarrhea, and hepatitis may interfere with the anti-cancer approach. Sargramostim (glycosylated, yeast-derived, recombinant human GM-CSF) is an agent that has been used in clinical practice for more than 30 years with a well-recognized safety profile and has been studied in many therapeutic areas. The mechanism of action of sargramostim may treat moderate-to-severe GI irAEs without impairing the anti-cancer therapy. Some early data also suggest a potential survival benefit. Through the differentiation/maturation of monocytes, macrophages, and neutrophils and induction of anti-inflammatory T cell responses, GM-CSF aids in GI homeostasis, mucosal healing, and mucosal immunity. GM-CSF knockout mice are susceptible to severe colitis which was prevented with murine GM-CSF administration. For some patients with GI mucosa and immune cell function impairment, e.g., Crohn's disease, sargramostim reduces disease severity. In a prospective, randomized study (ECOG 1608), advanced melanoma patients had a reduction in grade 3-5 GI irAEs and less frequent colonic perforation in the sargramostim plus ipilimumab arm compared to ipilimumab alone. Sargramostim continues to be studied with ICIs for the prophylactic management of irAEs while also potentially providing a survival benefit.

JAK-STAT signaling in inflammation and stress-related diseases: implications for therapeutic interventions

The Janus kinase-signal transducer and transcription activator pathway (JAK-STAT) serves as a cornerstone in cellular signaling, regulating physiological and pathological processes such as inflammation and stress. Dysregulation in this pathway can lead to severe immunodeficiencies and malignancies, and its role extends to neurotransduction and pro-inflammatory signaling mechanisms. Although JAK inhibitors (Jakinibs) have successfully treated immunological and inflammatory disorders, their application has generally been limited to diseases with similar pathogenic features. Despite the modest expression of JAK-STAT in the CNS, it is crucial for functions in the cortex, hippocampus, and cerebellum, making it relevant in conditions like Parkinson's disease and other neuroinflammatory disorders. Furthermore, the influence of the pathway on serotonin receptors and phospholipase C has implications for stress and mood disorders. This review expands the understanding of JAK-STAT, moving beyond traditional immunological contexts to explore its role in stress-related disorders and CNS function. Recent findings, such as the effectiveness of Jakinibs in chronic conditions such as rheumatoid arthritis, expand their therapeutic applicability. Advances in isoform-specific inhibitors, including filgotinib and upadacitinib, promise greater specificity with fewer off-target effects. Combination therapies, involving Jakinibs and monoclonal antibodies, aiming to enhance therapeutic specificity and efficacy also give great hope. Overall, this review bridges the gap between basic science and clinical application, elucidating the complex influence of the JAK-STAT pathway on human health and guiding future interventions.

Selective activation of STAT3 and STAT5 dictates the fate of myeloid progenitor cells

The molecular programs that govern the directed differentiation of myeloid progenitor cells are still poorly defined. Using a previously established immortalized, phenotypically normal myeloid progenitor cell model mEB8-ER, we unveil a new mechanism mediated by STAT5 and STAT3 at a bifurcation point of myeloid progenitor cell-fate specification. We find that myeloid progenitor cells can spontaneously differentiate into neutrophils with a basal level of STAT3 phosphorylation, which is enhanced by G-CSF treatment or STAT3 over-expression, leading to elevated neutrophil differentiation. Reduced STAT3 phosphorylation caused by GM-CSF treatment, STAT3 specific inhibitor, or STAT3 depletion leads to attenuated myeloid differentiation into neutrophils, while elevating differentiation into monocytes/macrophages. In contrast, STAT5 appears to have an antagonistic function to STAT3. When activated by GM-CSF, STAT5 promotes myeloid differentiation into monocytes/macrophages but inhibits neutrophil differentiation. At the mechanistic level, GM-CSF activates STAT5 to up-regulate SOCS3, which attenuates STAT3 phosphorylation and consequently neutrophil differentiation, while enhancing monocyte/macrophage differentiation. Furthermore, inhibition of STAT5 and STAT3 in primary myeloid progenitors recapitulates the results from the mEB8-ER model. Together, our findings provide new mechanistic insights into myeloid differentiation and may prove useful for the diagnosis and treatment of diseases related to abnormal myeloid differentiation.

M-MDSC in vitro generation from mouse bone marrow with IL-3 reveals high expression and functional activity of arginase 1

Myeloid-derived suppressor cells (MDSC) represent major regulators of immune responses, which can control T cells via their inducible nitric oxide synthase (iNOS)- and arginase 1 (Arg1)-mediated effector functions. While GM-CSF is well documented to promote MDSC development, little is known about this potential of IL-3, an established growth factor for mast cells. Here, we show that IL-3, similar to GM-CSF, generates monocytic MDSC (M-MDSC) from murine bone marrow (BM) cells after 3 days of in vitro culture. At this time point, predominantly CD11b⁺ CD49a⁺ monocytic and CD11b⁺ CD49a^- FcεR I^- neutrophilic cells were detectable, while CD11b^low/neg FcεR I⁺ mast cells accumulated only after extended culture periods. Both growth factors were equivalent in generating M-MDSC with respect to phenotype, cell yield and typical surface markers. However, IL-3 generated M-MDSC produced less TNF, IL-1β and IL-10 after activation with LPS + IFN-γ but showed higher Arg1 expression compared to GM-CSF generated M-MDSC. Arg1 was further induced together with iNOS after MDSC activation. Accordingly, an increased Arg1-dependent suppressor activity by the IL-3 generated M-MDSC was observed using respective iNOS and Arg1 inhibitors. Together, these data indicate that M-MDSC can be generated in vitro by IL-3, similar to GM-CSF, but with increased Arg1 expression and Arg1-mediated suppression capacity. This protocol now allows further in vitro studies on the role of IL-3 for MDSC biology.

Network analysis to explore the pharmacological mechanism of Shenmai injection in treating granulocytopenia and evidence-based medicine approach validation

BACKGROUND

Shenmai injection is frequently utilized in China to clinically treat granulocytopenia in oncology patients following chemotherapy. Despite this, the drug's therapeutic benefits remain a topic of contention, and its active components and potential treatment targets have yet to be established. The present study utilizes a network pharmacology approach to investigate the drug's active ingredients and possible therapeutic targets, and to evaluate the effectiveness of Shenmai injection in treating granulocytopenia through meta-analysis.

METHODS

In our subject paper, we utilized the TCMID database to investigate the active ingredients present in red ginseng and ophiopogon japonicus. To further identify molecular targets, we employed SuperPred, as well as OMIM, Genecards, and DisGeNET databases. Our focus was on targets associated with granulocytopenia. The DAVID 6.8 database was utilized to perform gene ontology functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Additionally, a protein-protein interaction network was established. The resulting "drug-key component-potential target-core pathway" network was used to predict the mechanism of action of Shenmai injection in the treatment of granulocytopenia. In order to evaluate the quality of the studies included in our analysis, we utilized the Cochrane Reviewers' Handbook. We then conducted a meta-analysis of the clinical curative effect of Shenmai injection for granulocytopenia, utilizing the Cochrane Collaboration's RevMan 5.3 software.

RESULTS

After conducting a thorough screening, the study identified 5 primary ingredients of Shenmai injection - ophiopogonoside a, β-patchoulene, ginsenoside rf, ginsenoside re, and ginsenoside rg1-that can potentially target 5 essential proteins: STAT3, TLR4, PIK3CA, PIK3R1, and GRB2. Additionally, Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that Shenmai injection can be beneficial in treating granulocytopenia by interacting with pathways such as HIF-1 signaling, T-cell receptor signaling, PI3K-Akt signaling, chemokine signaling, and FoxO signaling. The results of meta-analysis indicate that the treatment group exhibited superior performance in terms of both efficiency and post-treatment leukocyte count when compared to the control group.

CONCLUSION

In summary, studies in network pharmacology demonstrate that Shenmai injection exerts an impact on granulocytopenia via various components, targets, and mechanisms. Additionally, evidence-based studies provide strong support for the effectiveness of Shenmai injection in preventing and treating granulocytopenia.

The role of granulocyte-macrophage colony-stimulating factor in head and neck cancer

OBJECTIVE

To review the molecular mechanisms and biological roles of granulocyte-macrophage colony-stimulating factor (GM-CSF) in head and neck squamous cell carcinoma, highlighting its potential clinical applications.

DESIGN

The search terms "granulocyte-macrophage colony-stimulating factor", "GM-CSF", "CSF2″ and "head and neck squamous cell carcinoma" or "head and neck cancer" were queried in the PubMed/MEDLINE and Scopus databases.

RESULTS

Despite of being a widely expressed cytokine, the number of studies investigating the specific roles of GM-CSF in head and neck cancer was limited. Most of them investigated GM-CSF in conjunction with other cytokines. When studied alone, conflicting findings were observed in head and neck squamous cell carcinoma. GM-CSF has been shown to induce angiogenesis and local tumor invasion. Additionally, it has also been implicated in immune evasion. On the other hand, GM-CSF stimulated the differentiation of dendritic cells, which are responsible for presenting tumor antigens, and for the regulation of T cell function. Even with these paradoxical effects, there are few studies investigating the potential of GM-CSF as adjuvant therapy in head and neck cancer.

CONCLUSION

The effects of GM-CSF in head and neck cancer may be pro- or antitumor. Understanding how one arm and not the other is activated is essential to assess the applicability and the safety of this cytokine as a therapeutic agent.

Utility of monocyte HLA-DR and rationale for therapeutic GM-CSF in sepsis immunoparalysis

Sepsis, a heterogeneous clinical syndrome, features a systemic inflammatory response to tissue injury or infection, followed by a state of reduced immune responsiveness. Measurable alterations occur in both the innate and adaptive immune systems. Immunoparalysis, an immunosuppressed state, associates with worsened outcomes, including multiple organ dysfunction syndrome, secondary infections, and increased mortality. Multiple immune markers to identify sepsis immunoparalysis have been proposed, and some might offer clinical utility. Sepsis immunoparalysis is characterized by reduced lymphocyte numbers and downregulation of class II human leukocyte antigens (HLA) on innate immune monocytes. Class II HLA proteins present peptide antigens for recognition by and activation of antigen-specific T lymphocytes. One monocyte class II protein, mHLA-DR, can be measured by flow cytometry. Downregulated mHLA-DR indicates reduced monocyte responsiveness, as measured by ex-vivo cytokine production in response to endotoxin stimulation. Our literature survey reveals low mHLA-DR expression on peripheral blood monocytes correlates with increased risks for infection and death. For mHLA-DR, 15,000 antibodies/cell appears clinically acceptable as the lower limit of immunocompetence. Values less than 15,000 antibodies/cell are correlated with sepsis severity; and values at or less than 8000 antibodies/cell are identified as severe immunoparalysis. Several experimental immunotherapies have been evaluated for reversal of sepsis immunoparalysis. In particular, sargramostim, a recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF), has demonstrated clinical benefit by reducing hospitalization duration and lowering secondary infection risk. Lowered infection risk correlates with increased mHLA-DR expression on peripheral blood monocytes in these patients. Although mHLA-DR has shown promising utility for identifying sepsis immunoparalysis, absence of a standardized, analytically validated method has thus far prevented widespread adoption. A clinically useful approach for patient inclusion and identification of clinically correlated output parameters could address the persistent high unmet medical need for effective targeted therapies in sepsis.

Neuro-immune crosstalk in depressive symptoms of multiple sclerosis

Depressive disorders can occur in up to 50% of people with multiple sclerosis in their lifetime. If left untreated, comorbid major depressive disorders may not spontaneously remit and is associated with an increased morbidity and mortality. Conversely, epidemiological evidence supports increased psychiatric visit as a significant prodromal event prior to diagnosis of MS. Are there common molecular pathways that contribute to the co-development of MS and psychiatric illnesses? We discuss immune cells that are dysregulated in MS and how such dysregulation can induce or protect against depressive symptoms. This is not meant to be a comprehensive review of all molecular pathways but rather a framework to guide future investigations of immune responses in depressed versus euthymic people with MS. Currently, there is weak evidence supporting the use of antidepressant medication in comorbid MS patients. It is our hope that by better understanding the neuroimmune crosstalk in the context of depression in MS, we can enhance the potential for future therapeutic options.

Translating the biology of β common receptor-engaging cytokines into clinical medicine

The family of cytokines that comprises IL-3, IL-5, and GM-CSF was discovered over 30 years ago, and their biological activities and resulting impact in clinical medicine has continued to expand ever since. Originally identified as bone marrow growth factors capable of acting on hemopoietic progenitor cells to induce their proliferation and differentiation into mature blood cells, these cytokines are also recognized as key mediators of inflammation and the pathobiology of diverse immunologic diseases. This increased understanding of the functional repertoire of IL-3, IL-5, and GM-CSF has led to an explosion of interest in modulating their functions for clinical management. Key to the successful clinical translation of this knowledge is the recognition that these cytokines act by engaging distinct dimeric receptors and that they share a common signaling subunit called β-common or βc. The structural determination of how IL-3, IL-5, and GM-CSF interact with their receptors and linking this to their differential biological functions on effector cells has unveiled new paradigms of cell signaling. This knowledge has paved the way for novel mAbs and other molecules as selective or pan inhibitors for use in different clinical settings.

Granulocyte-macrophage colony stimulating factor enhances efficacy of nimustine rendezvousing with temozolomide plus irradiation in patients with glioblastoma

BACKGROUND

Glioblastoma is the most common and most aggressive type of primary brain tumor.

OBJECTIVE

The aim of this study was to investigate the efficacy and safety of intranasal granulocyte-macrophage colony stimulating factor (GM-CSF) administration combined with chemoradiotherapy in patients with glioblastoma who underwent surgery.

METHODS

Ninety-two patients were randomly divided into two groups: a control group (n= 46), who received radiotherapy with adjuvant local delivery of nimustine hydrochloride (ACNU) and systemic administration of temozolomide, and an intervention group (n= 46), who received intranasal GM-CSF prior to each cycle of adjuvant chemotherapy in addition to the treatment of the control group. Karnofsky performance status (KPS) scores, progression-free survival (PFS), overall survival (OS), and adverse effects were calculated and compared between the two groups.

RESULTS

Compared with the control group, the intervention group had longer PFS (7.8 vs. 6.9 months, P= 0.016) and OS (19.2 vs. 17.1 months, P= 0.045, without adjustment for interim analyses). The KPS scores were also higher in the intervention group than in the control group after 6 months (84.35 ± 8.86 vs. 80.65 ± 7.72; t= 4.552, P= 0.036). Furthermore, the patients in the intervention group had lower incidence of neutropenia and thrombocytopenia (8.7% vs. 29.5%, P= 0.012; 8.7% vs. 18.2%, P= 0.186). Other adverse events were similar in both groups, and most adverse events were grade I/II and resolved spontaneously.

CONCLUSION

Intranasal GM-CSF enhances the efficacy of the local ACNU administration combined with oral temozolomide chemotherapy. The survival and performance status were significantly improved in patients with glioblastoma after surgery. Additionally, the GM-CSF therapy was able to reduce the occurrence of chemotherapy-related neutropenia and thrombocytopenia.

CDK4/6 blockade provides an alternative approach for treatment of mismatch-repair deficient tumors

Mismatch repair-deficient (dMMR) tumors show a good response toward immune checkpoint inhibitors (ICI), but developing resistance impairs patients’ outcomes. Here, we compared the therapeutic potential of an α-PD-L1 antibody with the CDK4/6 inhibitor abemaciclib in two preclinical mouse models of dMMR cancer, focusing on immune-modulatory effects of either treatment. Abemaciclib monotherapy significantly prolonged overall survival of Mlh1^−/− and Msh2^{loxP/loxP;TgTg(Vil1-cre)} mice (Mlh1^−/−: 14.5 wks vs. 9.0 wks (α-PD-L1), and 3.5 wks (control); Msh2^{loxP/loxP;TgTg(Vil1-cre)}: 11.7 wks vs. 9.6 wks (α-PD-L1), and 2.0 wks (control)). The combination was not superior to either monotherapy. PET/CT imaging revealed individual response profiles, with best clinical responses seen with abemaciclib mono- and combination therapy. Therapeutic effects were accompanied by increasing numbers of tumor-infiltrating CD4⁺/CD8⁺ T-cells and lower numbers of M2-macrophages. Levels of T cell exhaustion markers and regulatory T cell counts declined. Expression analysis identified higher numbers of dendritic cells and neutrophils within tumors together with high expression of DNA damage repair genes as part of the global stress response. In Mlh1^−/− tumors, abemaciclib suppressed the PI3K/Akt pathway and led to induction of Mxd4/Myc. The immune-modulatory potential of abemaciclib renders this compound ideal for dMMR patients not eligible for ICI treatment.

Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor (rhu GM-CSF) as Adjuvant Therapy for Invasive Fungal Diseases

BACKGROUND

Sargramostim (yeast-derived, glycosylated recombinant human granulocyte-macrophage colony-stimulating factor [rhu GM-CSF]) augments innate and adaptive immune responses and accelerates hematopoietic recovery of chemotherapy-induced neutropenia. However, considerably less is known about its efficacy as adjunctive immunotherapy against invasive fungal diseases (IFDs).

METHODS

The clinical courses of 15 patients with pediatric malignancies and IFDs treated adjunctively with sargramostim at a single institution were analyzed in a retrospective cohort review. Further, a systematic review of published reports of rhu GM-CSF for IFDs was also conducted.

RESULTS

Among 65 cases, 15 were newly described pediatric patients and 50 were previously published cases of IFDs treated with rhu GM-CSF. Among the newly reported pediatric patients, IFDs were caused by Candida spp., Trichosporon sp., and molds (Aspergillus spp., Rhizopus sp., Lichtheimia sp., and Scedosporium sp). Twelve (80%) were neutropenic at baseline, and 12 (80%) were refractory to antifungal therapy. Among 12 evaluable patients, the overall response rate was 92% (8 [67%] complete responses, 3 [25%] partial responses, and 1 [8%] stable). Treatment is ongoing in the remaining 3 patients. Among 50 published cases (15 Candida spp., 13 Mucorales, 11 Aspergillus spp., 11 other organisms), 20 (40%) had baseline neutropenia and 36 (72%) were refractory to standard therapy before rhu GM-CSF administration. Consistent with responses in the newly reported patients, the overall response rate in the literature review was 82% (40 [80%] complete responses, 1 [2%] partial response, and 9 [18%] no response).

CONCLUSIONS

Sargramostim may be a potential adjunctive immunomodulator for selected patients with hematological malignancies and refractory IFDs.

Therapeutic Implementation of Oncolytic Viruses for Cancer Immunotherapy: Review of Challenges and Current Clinical Trials

The development of cancer therapeutics has evolved from general targets with radiation and chemotherapy and shifted toward treatments with a more specific mechanism of action such as small molecule kinase inhibitors, monoclonal antibodies against tumor antigens, or checkpoint inhibitors. Recently, oncolytic viruses (OVs) have come to the forefront as a viable option for cancer immunotherapy, especially for "cold" tumors, which are known to inhabit an immunologically suppressive tumor microenvironment. Desired characteristics of viruses are selected through genetic attenuation of uncontrolled virulence, and some genes are replaced with ones that enhance conditional viral replication within tumor cells. Treatment with OVs must overcome various hurdles such as premature viral suppression by the host's immune system and the dense stromal barrier. Currently, clinical studies investigate the efficacy of OVs in conjunction with various anti-cancer therapeutics, including radiotherapy, chemotherapy, immune checkpoint inhibitors, and monoclonal antibodies. Thus, future research should explore how cancer therapeutics work synergistically with certain OVs in order to create more effective combination therapies and improve patient outcomes.

Pharmacophore-Based Virtual Screening and Experimental Validation of Pyrazolone-Derived Inhibitors toward Janus Kinases

Janus kinases (JAKs) are nonreceptor protein tyrosine kinases that play a role in a broad range of cell signaling. JAK2 and JAK3 have been involved in the pathogenesis of common lymphoid-derived diseases and leukemia cancer. Thus, inhibition of both JAK2 and JAK3 can be a potent strategy to reduce the risk of these diseases. In the present study, the pharmacophore models built based on the commercial drug tofacitinib and the JAK2/3 proteins derived from molecular dynamics (MD) trajectories were employed to search for a dual potent JAK2/3 inhibitor by a pharmacophore-based virtual screening of 54 synthesized pyrazolone derivatives from an in-house data set. Twelve selected compounds from the virtual screening procedure were then tested for their inhibitory potency against both JAKs in the kinase assay. The in vitro kinase inhibition experiment indicated that compounds 3h, TK4g, and TK4b can inhibit both JAKs in the low nanomolar range. Among them, the compound TK4g showed the highest protein kinase inhibition with the half-maximal inhibitory concentration (IC₅₀) value of 12.61 nM for JAK2 and 15.80 nM for JAK3. From the MD simulations study, it could be found that the sulfonamide group of TK4g can form hydrogen bonds in the hinge region at residues E930 and L932 of JAK2 and E903 and L905 of JAK3, while van der Waals interaction also plays a dominant role in ligand binding. Altogether, TK4g, found by virtual screening and biological tests, could serve as a novel therapeutical lead candidate.

GM-CSF: A Double-Edged Sword in Cancer Immunotherapy

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine that drives the generation of myeloid cell subsets including neutrophils, monocytes, macrophages, and dendritic cells in response to stress, infections, and cancers. By modulating the functions of innate immune cells that serve as a bridge to activate adaptive immune responses, GM-CSF globally impacts host immune surveillance under pathologic conditions. As with other soluble mediators of immunity, too much or too little GM-CSF has been found to promote cancer aggressiveness. While too little GM-CSF prevents the appropriate production of innate immune cells and subsequent activation of adaptive anti-cancer immune responses, too much of GM-CSF can exhaust immune cells and promote cancer growth. The consequences of GM-CSF signaling in cancer progression are a function of the levels of GM-CSF, the cancer type, and the tumor microenvironment. In this review, we first discuss the secretion of GM-CSF, signaling downstream of the GM-CSF receptor, and GM-CSF’s role in modulating myeloid cell homeostasis. We then outline GM-CSF’s anti-tumorigenic and pro-tumorigenic effects both on the malignant cells and on the non-malignant immune and other cells in the tumor microenvironment. We provide examples of current clinical and preclinical strategies that harness GM-CSF’s anti-cancer potential while minimizing its deleterious effects. We describe the challenges in achieving the Goldilocks effect during administration of GM-CSF-based therapies to patients with cancer. Finally, we provide insights into how technologies that map the immune microenvironment spatially and temporally may be leveraged to intelligently harness GM-CSF for treatment of malignancies.

Differential gene expression reveals host factors for viral shedding variation in mallards (Anas platyrhynchos) infected with low-pathogenic avian influenza virus

Intraspecific variation in pathogen shedding impacts disease transmission dynamics; therefore, understanding the host factors associated with individual variation in pathogen shedding is key to controlling and preventing outbreaks. In this study, ileum and bursa of Fabricius tissues of wild-bred mallards (Anas platyrhynchos) infected with low-pathogenic avian influenza (LPAIV) were evaluated at various post-infection time points to determine genetic host factors associated with intraspecific variation in viral shedding. By analysing transcriptome sequencing data (RNA-seq), we found that LPAIV-infected wild-bred mallards do not exhibit differential gene expression compared to uninfected birds, but that gene expression was associated with cloacal viral shedding quantity early in the infection. In both tissues, immune gene expression was higher in high/moderate shedding birds compared to low shedding birds, and significant positive relationships with viral shedding were observed. In the ileum, expression for host genes involved in viral cell entry was lower in low shedders compared to moderate shedders at 1 day post-infection (DPI), and expression for host genes promoting viral replication was higher in high shedders compared to low shedders at 2 DPI. Our findings indicate that viral shedding is a key factor for gene expression differences in LPAIV-infected wild-bred mallards, and the genes identified in this study could be important for understanding the molecular mechanisms driving intraspecific variation in pathogen shedding.

Breast Cancer Vaccines: Disappointing or Promising?

Breast cancer has become the most commonly diagnosed cancer globally. The relapse and metastasis of breast cancer remain a great challenge despite advances in chemotherapy, endocrine therapy, and HER2 targeted therapy in the past decades. Innovative therapeutic strategies are still critically in need. Cancer vaccine is an attractive option as it aims to induce a durable immunologic response to eradicate tumor cells. Different types of breast cancer vaccines have been evaluated in clinical trials, but none has led to significant benefits. Despite the disappointing results at present, new promise from the latest study indicates the possibility of applying vaccines in combination with anti-HER2 monoclonal antibodies or immune checkpoint blockade. This review summarizes the principles and mechanisms underlying breast cancer vaccines, recapitulates the type and administration routes of vaccine, reviews the current results of relevant clinical trials, and addresses the potential reasons for the setbacks and future directions to explore.

Immunomodulatory effects of mesenchymal stem cells in peripheral nerve injury

Various immune cells and cytokines are present in the aftermath of peripheral nerve injuries (PNI), and coordination of the local inflammatory response is of great significance for the recovery of PNI. Mesenchymal stem cells (MSCs) exhibit immunosuppressive and anti-inflammatory abilities which can accelerate tissue regeneration and attenuate inflammation, but the role of MSCs in the regulation of the local inflammatory microenvironment after PNI has not been widely studied. Here, we summarize the known interactions between MSCs, immune cells, and inflammatory cytokines following PNI with a focus on the immunosuppressive role of MSCs. We also discuss the immunomodulatory potential of MSC-derived extracellular vesicles as a new cell-free treatment for PNI.

Neutrophil Homeostasis and Emergency Granulopoiesis: The Example of Systemic Juvenile Idiopathic Arthritis

Neutrophils are key pathogen exterminators of the innate immune system endowed with oxidative and non-oxidative defense mechanisms. More recently, a more complex role for neutrophils as decision shaping cells that instruct other leukocytes to fine-tune innate and adaptive immune responses has come into view. Under homeostatic conditions, neutrophils are short-lived cells that are continuously released from the bone marrow. Their development starts with undifferentiated hematopoietic stem cells that pass through different immature subtypes to eventually become fully equipped, mature neutrophils capable of launching fast and robust immune responses. During severe (systemic) inflammation, there is an increased need for neutrophils. The hematopoietic system rapidly adapts to this increased demand by switching from steady-state blood cell production to emergency granulopoiesis. During emergency granulopoiesis, the de novo production of neutrophils by the bone marrow and at extramedullary sites is augmented, while additional mature neutrophils are rapidly released from the marginated pools. Although neutrophils are indispensable for host protection against microorganisms, excessive activation causes tissue damage in neutrophil-rich diseases. Therefore, tight regulation of neutrophil homeostasis is imperative. In this review, we discuss the kinetics of neutrophil ontogenesis in homeostatic conditions and during emergency myelopoiesis and provide an overview of the different molecular players involved in this regulation. We substantiate this review with the example of an autoinflammatory disease, i.e. systemic juvenile idiopathic arthritis.

Messing with βc: A unique receptor with many goals

Our understanding of the biological role of the βc family of cytokines has evolved enormously since their initial identification as bone marrow colony stimulating factors in the 1960's. It has become abundantly clear over the intervening decades that this family of cytokines has truly astonishing pleiotropic capacity, capable of regulating not only hematopoiesis but also many other normal and pathological processes such as development, inflammation, allergy and cancer. As noted in the current pandemic, βc cytokines contribute to the cytokine storm seen in acutely ill COVID-19 patients. Ongoing studies to discover how these cytokines activate their receptor are revealing insights into the fundamental mechanisms that give rise to cytokine pleiotropy and are providing tantalizing glimpses of how discrete signaling pathways may be dissected for activation with novel ligands for therapeutic benefit.

Role of molecularly-cloned hematopoietic growth factors after acute high-dose radiation exposures

Therapy of acute, high-dose whole-body exposures of humans to ionizing radiations is a complex medical challenge. Since 1944 more than 400 radiologic accidents have been registered with more than 3000 substantial radiation exposures and 127 fatalities. There are several potential interventions including supportive care, transfusions, preventative or therapeutic anti-infection drugs, molecularly-cloned myeloid growth factors and hematopoietic cell transplants. We discuss the use of the granulocyte and granulocyte-macrophage colony-stimulating factor (G-CSF and GM-CSF) to treat acute high-dose ionizing radiation exposures. Considerable data in experimental models including monkeys indicate use of these drugs accelerates bone marrow recovery and in some but not all instances increases survival. In ten accidents since 1996, 30 victims received G-CSF alone or with other growth factors. Twenty-six victims survived. In seven accidents since 1986, 28 victims received GM-CSF alone or with other growth factors; 18 victims survived. However, absent control or data from randomized trials, it is not possible to know with certainty what role, if any, receiving G-CSF or GM-CSF was of benefit. Given the favorablebenefit-to-riskratio of molecularly-cloned myeloid growth factors, their use soon after exposure to acute, high-dose whole-body ionizing radiations is reasonable.

GM-CSF: Master regulator of the T cell-phagocyte interface during inflammation

The role of granulocyte-macrophage colony-stimulating factor (GM-CSF) was sequentially redefined during the past decades. Originally described as a hematopoietic growth factor for myelopoiesis, GM-CSF was recognized as a central mediator of inflammation bridging the innate and adaptive arms of the immune system. Phagocytes sensing GM-CSF adapt an inflammatory phenotype and facilitate pathogen clearance. However, in the context of chronic tissue inflammation, GM-CSF secreted by tissue-invading lymphocytes has detrimental effects by licensing tissue damage and hyperinflammation. Accordingly, therapeutic intervention at the T cell-phagocyte interface represents an attractive target to ameliorate disease progression and immunopathology. Although GM-CSF is largely dispensable for steady state myelopoiesis, dysregulation, as seen in chronic inflammatory diseases, may however lead to disrupted haematopoiesis and long-term effects on bone marrow output. Here, we will survey the role of GM-CSF during inflammation, discuss the extent to which GM-CSF-secreting T cells, debate their introduction as a separate T cell lineage and explore current and future clinical implications of GM-CSF in human disease settings.

Cytokine Networks in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic systemic inflammation causing progressive joint damage that can lead to lifelong disability. The pathogenesis of RA involves a complex network of various cytokines and cells that trigger synovial cell proliferation and cause damage to both cartilage and bone. Involvement of the cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 is central to the pathogenesis of RA, but recent research has revealed that other cytokines such as IL-7, IL-17, IL-21, IL-23, granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-18, IL-33, and IL-2 also play a role. Clarification of RA pathology has led to the development of therapeutic agents such as biological disease-modifying anti-rheumatic drugs (DMARDs) and Janus kinase (JAK) inhibitors, and further details of the immunological background to RA are emerging. This review covers existing knowledge regarding the roles of cytokines, related immune cells and the immune system in RA, manipulation of which may offer the potential for even safer and more effective treatments in the future.

Non-Operative Options for Loco-regional Melanoma

Malignant melanoma is the 5th most common cancer and stage IV melanoma accounts for approximately 4% of new melanoma diagnoses in the United States. The prognosis for regionally advanced disease is poor, but there have been numerous recent advances in the medical management of melanoma in-transit metastases. The goal of this paper is to review currently accepted treatment options for in-transit metastases and introduce emerging therapies. Therapies to be discussed include limb perfusion and infusion, immunotherapy, checkpoint inhibitors, and radiation therapy.

CISH attenuates homeostatic cytokine signaling to promote lung-specific macrophage programming and function

[Figure: see text].

Development of a Novel Cytokine Vehicle Using Filamentous Phage Display for Colorectal Cancer Treatment

Due to its highly immunogenic nature and the great engineerability, filamentous phage has shown promising antitumor activities in preclinical studies. Previous designs of antitumor phage mainly focused on tumor targeting using a cancer-specific moiety displayed on the minor capsid protein, pIII. In this work, we developed a new therapeutic platform of filamentous phage, in which the major capsid protein pVIII was utilized for displaying an antitumor cytokine. We showcased that a 16.1-kD cytokine GM-CSF could be efficiently presented on the M13 phage particle using the 8 + 8 type display system through a highly tolerable pVIII variant P8(1a). We verified that the GM-CSF phage was a potent activator for STAT5 signaling in murine macrophage. The GM-CSF phage significantly reduced the tumor size by more than 50% as compared to the unmodified phage in a murine colorectal cancer model. Immunological profiling of the tumor-infiltrating leukocytes revealed that an increase of CD4+ lymphocytes in the GM-CSF phage treatment group. Furthermore, the combined therapy of the GM-CSF phage and radiation greatly improved the therapeutic potency with a 100% survival rate and a 25% complete remission rate. We observed that the IFN-γ expression was dramatically up-regulated by the combined therapy in multiple types of tumor-infiltrating immune cells. Overall, we created a novel vehicle for cytokine therapy using the pVIII filamentous phage display. This new platform can be multiplexed with other phage engineering approaches, such as displaying targeting ligands on pIII or encapsulating therapeutic genes inside phage capsids, to create multifunctional nanoparticles for cancer therapy.

Sargramostim (rhu GM-CSF) as Cancer Therapy (Systematic Review) and An Immunomodulator. A Drug Before Its Time?

BACKGROUND

Sargramostim [recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF)] was approved by US FDA in 1991 to accelerate bone marrow recovery in diverse settings of bone marrow failure and is designated on the list of FDA Essential Medicines, Medical Countermeasures, and Critical Inputs. Other important biological activities including accelerating tissue repair and modulating host immunity to infection and cancer via the innate and adaptive immune systems are reported in pre-clinical models but incompletely studied in humans.

OBJECTIVE

Assess safety and efficacy of sargramostim in cancer and other diverse experimental and clinical settings.

METHODS AND RESULTS

We systematically reviewed PubMed, Cochrane and TRIP databases for clinical data on sargramostim in cancer. In a variety of settings, sargramostim after exposure to bone marrow-suppressing agents accelerated hematologic recovery resulting in fewer infections, less therapy-related toxicity and sometimes improved survival. As an immune modulator, sargramostim also enhanced anti-cancer responses in solid cancers when combined with conventional therapies, for example with immune checkpoint inhibitors and monoclonal antibodies.

CONCLUSIONS

Sargramostim accelerates hematologic recovery in diverse clinical settings and enhances anti-cancer responses with a favorable safety profile. Uses other than in hematologic recovery are less-well studied; more data are needed on immune-enhancing benefits. We envision significantly expanded use of sargramostim in varied immune settings. Sargramostim has the potential to reverse the immune suppression associated with sepsis, trauma, acute respiratory distress syndrome (ARDS) and COVID-19. Further, sargramostim therapy has been promising in the adjuvant setting with vaccines and for anti-microbial-resistant infections and treating autoimmune pulmonary alveolar proteinosis and gastrointestinal, peripheral arterial and neuro-inflammatory diseases. It also may be useful as an adjuvant in anti-cancer immunotherapy.

The Many Faces of JAKs and STATs Within the COVID-19 Storm

The positive-sense single stranded RNA virus, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), resulted in a global pandemic with horrendous health and economic consequences not seen in a century. At a finer scale, immunologically, many of these devastating effects by SARS-CoV-2 can be traced to a "cytokine storm" resulting in the simultaneous activation of Janus Kinases (JAKs) and Signal Transducers and Activators of Transcription (STAT) proteins downstream of the many cytokine receptor families triggered by elevated cytokines found in Coronavirus Disease 2019 (COVID-19). In this report, cytokines found in the storm are discussed in relation to the JAK-STAT pathway in response to SARS-CoV-2 and the lessons learned from RNA viruses and previous Coronaviruses (CoVs). Therapeutic strategies to counteract the SARS-CoV-2 mediated storm are discussed with an emphasis on cell signaling and JAK inhibition.

Sargramostim and immune checkpoint inhibitors: combinatorial therapeutic studies in metastatic melanoma

The use of immune checkpoint inhibitors in patients with metastatic melanoma generates clinical benefit, including improved survival. Yet disease resistance and immune-related adverse events persist as unmet needs. Sargramostim, a yeast-derived recombinant human GM-CSF, has shown clinical activity against diverse solid tumors, including metastatic melanoma. Here we review the use of sargramostim for treatment of advanced melanoma. Potential sargramostim applications in melanoma draw on the unique ability of GM-CSF to link innate and adaptive immune responses. We review preclinical and translational data describing the mechanism of action of sargramostim and synergy with immune checkpoint inhibitors to enhance efficacy and reduce treatment-related toxicity.

Development and Functions of Alveolar Macrophages

Macrophages residing in various tissue types are unique in terms of their anatomical locations, ontogenies, developmental pathways, gene expression patterns, and immunological functions. Alveolar macrophages (AMs) reside in the alveolar lumen of the lungs and serve as the first line of defense for the respiratory tract. The immunological functions of AMs are implicated in the pathogenesis of various pulmonary diseases such as allergic asthma, chronic obstructive pulmonary disorder (COPD), pulmonary alveolar proteinosis (PAP), viral infection, and bacterial infection. Thus, the molecular mechanisms driving the development and function of AMs have been extensively investigated. In this review article, we discuss the roles of granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor (TGF)-β in AM development, and provide an overview of the anti-inflammatory and proinflammatory functions of AMs in various contexts. Notably, we examine the relationships between the metabolic status of AMs and their development processes and functions. We hope that this review will provide new information and insight into AM development and function.

Phase I Trial of Cemiplimab, Radiotherapy, Cyclophosphamide, and Granulocyte Macrophage Colony-Stimulating Factor in Patients with Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

LESSONS LEARNED

Cemiplimab in combination with radiation therapy, cyclophosphamide, and granulocyte macrophage colony-stimulating factor did not demonstrate efficacy above what can be achieved with other PD-1 inhibitor monotherapies in patients with refractory and metastatic head and neck squamous cell carcinoma. The safety profile of cemiplimab combination therapy was consistent with previously reported safety profiles of cemiplimab monotherapy. No new safety signal was observed.

BACKGROUND

Refractory and metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) generally does not respond to PD-1 inhibitor monotherapy. Cemiplimab is a human anti-PD-1 monoclonal antibody. An expansion cohort enrolled patients with R/M HNSCC in a phase I study combining cemiplimab plus radiation therapy (RT), cyclophosphamide, and granulocyte macrophage colony-stimulating factor (GM-CSF).

METHODS

Patients with R/M HNSCC refractory to at least first-line therapy and for whom palliative RT is clinically indicated received cemiplimab plus RT, cyclophosphamide, and GM-CSF. The co-primary objectives were the safety, tolerability, and efficacy of cemiplimab plus RT, cyclophosphamide, and GM-CSF in 15 patients with R/M HNSCC.

RESULTS

Fifteen patients were enrolled. Patients discontinued treatment due to progression of disease. The most common treatment-emergent adverse events (TEAEs) of any grade were fatigue (40.0%), constipation (26.7%), and asthenia, dyspnea, maculo-papular rash, and pneumonia (each 20%). The only grade ≥3 TEAE that occurred in two patients was pneumonia (13.3%). By investigator assessment, there was one partial response (6.7%); disease control rate was 40.0% (95% confidence interval [CI], 16.3-67.7; five patients with stable disease); seven patients had progressive disease, and two were not evaluable. Median progression-free survival by investigator assessment was 1.8 months (95% CI, 1.7-4.7).

CONCLUSION

The regimen demonstrated tolerability but not efficacy above that which can be achieved with anti-PD-1 inhibitor monotherapy for R/M HNSCC.

In-transit metastatic cutaneous melanoma: current management and future directions

Management of in-transit melanoma encompasses a variety of possible treatment pathways and modalities. Depending on the location of disease, number of lesions, burden of disease and patient preference and characteristics, some treatments may be more beneficial than others. After full body radiographic staging is performed to rule out metastatic disease, curative therapy may be performed through surgical excision, intraarterial regional perfusion and infusion therapies, intralesional injections, systemic therapies or various combinations of any of these. While wide excision is limited in indication to superficial lesions that are few in number, the other listed therapies may be effective in treating unresectable disease. Where intraarterial perfusion based therapies have been shown to successfully treat extremity disease, injectable therapies can be used in lesions of the head and neck. Although systemic therapies for in-transit melanoma have limited specific data to support their primary use for in-transit disease, there are patients who may not be eligible for any of the other options, and current clinical trials are exploring the use of concurrent and sequential use of regional and systemic therapies with early results suggesting a synergistic benefit for oncologic response and outcomes.

Mutated GM-CSF-based CAR-T cells targeting CD116/CD131 complexes exhibit enhanced anti-tumor effects against acute myeloid leukaemia

Objectives

As the prognosis of relapsed/refractory (R/R) acute myeloid leukaemia (AML) remains poor, novel treatment strategies are urgently needed. Clinical trials have shown that chimeric antigen receptor (CAR)‐T cells for AML are more challenging than those targeting CD19 in B‐cell malignancies. We recently developed piggyBac‐modified ligand‐based CAR‐T cells that target CD116/CD131 complexes, also known as the GM‐CSF receptor (GMR), for the treatment of juvenile myelomonocytic leukaemia. This study therefore aimed to develop a novel therapeutic method for R/R AML using GMR CAR‐T cells.

Methods

To further improve the efficacy of the original GMR CAR‐T cells, we have developed novel GMR CAR vectors incorporating a mutated GM‐CSF for the antigen‐binding domain and G4S spacer. All GMR CAR‐T cells were generated using a piggyBac‐based gene transfer system. The anti‐tumor effect of GMR CAR‐T cells was tested in mouse AML xenograft models.

Results

Nearly 80% of the AML cells predominant in myelomonocytic leukaemia were found to express CD116. GMR CAR‐T cells exhibited potent cytotoxic activities against CD116⁺ AML cells in vitro. Furthermore, GMR CAR‐T cells incorporating a G4S spacer significantly improved long‐term in vitro and in vivo anti‐tumor effects. By employing a mutated GM‐CSF at residue 21 (E21K), the anti‐tumor effects of GMR CAR‐T cells were also improved especially in long‐term in vitro settings. Although GMR CAR‐T cells exerted cytotoxic effects on normal monocytes, their lethality on normal neutrophils, T cells, B cells and NK cells was minimal.

Conclusions

GMR CAR‐T cell therapy represents a promising strategy for CD116⁺ R/R AML.

Invasive fungal disease and the immunocompromised host including allogeneic hematopoietic cell transplant recipients: Improved understanding and new strategic approach with sargramostim

In hosts with damaged or impaired immune systems such as those undergoing hematopoietic cell transplant (HCT) or intensive chemotherapy, breakthrough fungal infections can be fatal. Risk factors for breakthrough infections include severe neutropenia, use of corticosteroids, extended use of broad-spectrum antibiotics, and intensive care unit admission. An individual's cumulative state of immunosuppression directly contributes to the likelihood of experiencing increased infection risk. Incidence of invasive fungal infection (IFI) after HCT may be up to 5-8%. Early intervention may improve IFI outcomes, although many infections are resistant to standard therapies (voriconazole, caspofungin, micafungin, amphotericin B, posaconazole or itraconazole, as single agents or in combination). We review herein several contributing factors that may contribute to the net state of immunosuppression in recipients of HCT. We also review a new approach for IFI utilizing adjunctive therapy with sargramostim, a yeast-derived recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF).

Comments on the ambiguity of selected surface markers, signaling pathways and omics profiles hampering the identification of myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSC) are important immune-regulatory cells but their identification remains difficult. Here, we provide a critical view on selected surface markers, transcriptional and translational pathways commonly used to identify MDSC by specific, their developmental origin and new possibilities by transcriptional or proteomic profiling. Discrimination of MDSC from their non-suppressive counterparts is a prerequisite for the development of successful therapies. Understanding the switch mechanisms that direct granulocytic and monocytic development into a pro-inflammatory or anti-inflammatory direction will be crucial for therapeutic strategies. Manipulation of these myeloid checkpoints are exploited by tumors and pathogens, such as M. tuberculosis (Mtb), HIV or SARS-CoV-2, that induce MDSC for immune evasion. Thus, specific markers for MDSC identification may reveal also novel molecular candidates for therapeutic intervention at the level of MDSC.

Granulocyte macrophage colony-stimulating factor has come of age: From a vaccine adjuvant to antiviral immunotherapy

GM-CSF acts as a pro-inflammatory cytokine and a key growth factor produced by several immune cells such as macrophages and activated T cells. In this review, we discuss recent studies that point to the crucial role of GM-CSF in the immune response against infections. Upon induction, GM-CSF activates four main signalling networks including the JAK/STAT, PI3K, MAPK, and NFκB pathways. Many of these transduction pathways such as JAK/STAT signal via proteins commonly activated with other antiviral signalling cascades, such as those induced by IFNs. GM-CSF also helps defend against respiratory infections by regulating alveolar macrophage differentiation and enhancing innate immunity in the lungs. Here, we also summarize the numerous clinical trials that have taken advantage of GM-CSF's mechanistic attributes in immunotherapy. Moreover, we discuss how GM-CSF is used as an adjuvant in vaccines and how its activity is interfered with to reduce inflammation such as in the case of COVID-19. This review brings forth the current knowledge on the antiviral actions of GM-CSF, the associated signalling cascades, and its application in immunotherapy.

Deletion of IKK2 in haematopoietic cells of adult mice leads to elevated interleukin-6, neutrophilia and fatal gastrointestinal inflammation

The IκB kinase complex, consisting of IKK1, IKK2 and the regulatory subunit NEMO, is required for NF-κB signalling following the activation of several cell surface receptors, such as members of the Tumour Necrosis Factor Receptor superfamily and the Interleukin-1 Receptor. This is critical for haematopoietic cell proliferation, differentiation, survival and immune responses. To determine the role of IKK in the regulation of haematopoiesis, we used the Rosa26^Cre-ERT2 Cre/lox recombination system to achieve targeted, haematopoietic cell-restricted deletion of the genes for IKK1 or IKK2 in vivo. We found that the IKK complex plays a critical role in haematopoietic cell development and function. Deletion of IKK2, but not loss of IKK1, in haematopoietic cells led to an expansion of CD11b/Gr-1-positive myeloid cells (neutrophilia), severe anaemia and thrombocytosis, with reduced numbers of long-term haematopoietic stem cells (LT-HSCs), short-term haematopoietic stem cells (ST-HSCs) and multipotential progenitor cells (MPPs), increased circulating interleukin-6 (IL-6) and severe gastrointestinal inflammation. These findings identify distinct functions for the two IKK catalytic subunits, IKK1 and IKK2, in the haematopoietic system.

Carbon ion triggered immunogenic necroptosis of nasopharyngeal carcinoma cells involving necroptotic inhibitor BCL-x

To explore the potential and mechanisms of necroptosis, a form of immunogenic cell death, induced by carbon ion as compared to photon beams in established photon resistant- (PR-) and sensitive nasopharyngeal carcinoma (NPC) cells. MLKL is considered a central executor of necroptosis and phosphorylation of MLKL (p-MLKL) was a critical event of necroptosis. The clonogenic survival and DNA microarray demonstrated that after repeated photon irradiation, radiosensitive NPC cells became apoptosis-resistant but could be effectively inhibited by carbon ion irradiation. The relative biologic effectiveness (RBE) at D10 and D37 were 2.15 and 2.78 for PR-NPC cells. Carbon ion induced delayed DNA damage repair, cell cycle arrest, cytogenetic damage, morphological change and cell necrosis, indicating the possibility of necroptosis in both PR- and sensitive NPC cell types. The lower expression of necroptotic inhibitors (caspase-8 and Bcl-x) and higher level of MLKL in PR-NPC cells showed it was relatively more predisposed to necroptosis compared to the sensitive cells. Subsequent experiments demonstrated the significant upregulation of p-MLKL in the PR-NPC cells treated by carbon ion (4 Gy) compared with photon irradiation at both physical (4 Gy) and RBE (10 Gy) doses (P≤0.0001). Moreover, carbon ion induced a robust (up to 28 folds) p-MLKL in the PR-NPC cells as well as sensitive cells (up to 6-fold) coupled with a lower level of BCL-x expression and increased GM-CSF implicated in resculputure of immune system. These results suggested that carbon ion could induce necroptosis of NPC cells, especially in PR-NPC cells, and its mechanisms involve BCL-x.

The Truncated Splice Variant of the Granulocyte-Macrophage-Colony-Stimulating Factor Receptor β- Chain in Peripheral Blood Serves as Severity Biomarker of Respiratory Failure in Newborns

BACKGROUND

The granulocyte-macrophage-colony-stimulating factor (GM-CSF) plays an important role in surfactant homeostasis. βC is a subunit of the GM-CSF receptor (GM-CSF-R), and its activation mediates surfactant catabolism in the lung. βIT is a physiological, truncated isoform of βC and is known to act as physiological inhibitor of βC.

OBJECTIVE

The aim of this study was to determine the ratio of βIT and βC in the peripheral blood of newborns and its association with the degree of respiratory failure at birth.

METHODS

We conducted a prospective cohort study in newborns with various degrees of respiratory impairment at birth. Respiratory status was assessed by a score ranging from no respiratory impairment (0) to invasive respiratory support (3). βIT and βC expression were determined in peripheral blood cells by real-time PCR. βIT expression, defined as the ratio of βIT and βC, was correlated with the respiratory score.

RESULTS

βIT expression was found in all 59 recruited newborns with a trend toward higher βIT in respiratory ill (score 2, 3) newborns than respiratory healthy newborns ([score 0, 1]; p = 0.066). Seriously ill newborns (score 3) had significantly higher βIT than healthy newborns ([score 0], p = 0.010). Healthy preterm infants had significantly higher βIT expression than healthy term infants (p = 0.019).

CONCLUSIONS

βIT is expressed in newborns with higher expression in respiratory ill than respiratory healthy newborns. We hypothesize that βIT may have a protective effect in postnatal pulmonary adaptation acting as a physiological inhibitor of βC and, therefore, maintaining surfactant in respiratory ill newborns.

Emerging drugs for the treatment of chronic myelomonocytic leukemia

Introduction: Chronic myelomonocytic leukemia (CMML) is a clonal hematologic disorder with heterogenous prognosis, but with no curative therapies with exception of allogeneic transplant. Therapeutic options for patients with CMML are limited, and although hypomethylating agents such as azacitidine and decitabine are the standard of care, only 40% of patients achieve a response, and most responses are transient. Over the last 5 years, significant advances have been made in the understanding of the clonal landscape of CMML, some of the mechanisms associated to resistance to HMA, and other key biological processes involved in disease pathogenesis. Areas covered: The current article reviews the most relevant emerging therapies currently undergoing clinical trials for the treatment of previously untreated or relapsed CMML. Expert opinion: The presence of recurrent somatic mutations in CMML represents therapeutic opportunities to utilize specific small molecule inhibitors such as IDH, FLT3, MEK/ERK, PLK1, or splicing inhibitors and modulators. In addition, other novel agents such as immune therapies, BCL2 or MCL1 inhibitors and other monoclonal antibodies could lead to therapeutic advances. Identifying specific patient populations likely to benefit from some of these interventions, and development of optimal combinations will remain the challenge when determining their role in therapy.

Comprehensive Evaluation of Immune-Checkpoint DNA Cancer Vaccines in a Rat Cholangiocarcinoma Model

Cholangiocarcinoma (CCA) is a malignant tumor with aggressive biological behavior. Immune checkpoints such as cytotoxic T-lymphocyte antigen 4 (CTLA4) and antiprogrammed death 1 (PD-1) are critical immune-checkpoint molecules that repress T-cell activation. The DNA vaccine potential against CTLA4 and PD-1 in CCA is unknown. We used a thioacetamide (TAA)-induced intrahepatic cholangiocarcinoma (iCCA) rat model to investigate the DNA vaccine potential against CTLA4, PD-1, and PD-L1. We detected PD-L1 expression in CCA and CD8⁺ T-cell infiltration during CCA progression in rats. We validated antibody production, carcinogenesis, and CD8⁺ T-cell infiltration in rats receiving DNA vaccination against PD-1, PD-L1, or CTLA4. In our TAA-induced iCCA rat model, the expression of PD-L1 and the infiltration of CD8⁺ T cells increased as in rat CCA tumorigenesis. PD-1 antibodies in rats were not increased after receiving PD-1 DNA vaccination, and CCA tumor growth was not suppressed. However, in rats receiving PD-L1–CTLA4 DNA vaccination, CCA tumor growth was inhibited, and the antibodies of PD-L1 and CTLA4 were produced. Furthermore, the number of CD8⁺ T cells was enhanced after PD-L1–CTLA4 DNA vaccination. DNA vaccination targeting CTLA4–PD-L1 triggered the production of specific antibodies and suppressed tumor growth in TAA-induced iCCA rats.

Autologous non-human primate model for safety assessment of piggyBac transposon-mediated chimeric antigen receptor T cells on granulocyte-macrophage colony-stimulating factor receptor

Objectives

Chimeric antigen receptor (CAR)‐T cell therapy redirected to specific antigens on tumor cells is a promising immunotherapy strategy for various cancers. Most target antigens are also expressed on normal tissues at varying levels, and therefore, a considerable challenge in the field is determining safety profiles, including life‐threatening off‐tumor and off‐target toxicities. The granulocyte–macrophage colony‐stimulating factor receptor (hGMR) is a promising target for CAR T‐cell therapy for a subset of acute myelocytic leukaemia, although it is also expressed on normal cells including monocytes, macrophages, CD34‐positive haematopoietic cells and vascular endothelial cells. hGMR and other immune‐related proteins are highly conserved between humans and cynomolgus macaques (Macaca fascicularis). Therefore, in this study, we engineered cynomolgus T cells to express CAR molecules redirected to hGMR by piggyBac (PB) transposon‐based gene transfer and adoptively transferred autologous hGMR‐CAR T cells into cynomolgus macaques.

Methods

We established PB‐mediated human GMR (hGMR)‐specific CAR T cells using cynomolgus peripheral blood mononuclear cells and transferred them into autologous individuals, and evaluated the potential toxicity related to hGMR‐CAR T cells.

Results

hGMR‐CAR T cells did not exert overt organ toxicities such as bone marrow suppression, monocytopenia and vasculitis, although they recognised and killed cynomolgus monocytes and macrophages in vitro.

Conclusion

Although our model did not simulate a tumor‐bearing model, it supports the safety of hGMR‐CAR T cells and demonstrates the usefulness of a non‐human primate model to evaluate the safety of T‐cell products by assessing off‐tumor/off‐target toxicity before clinical trials.

Skeletal muscle healing by M1-like macrophages produced by transient expression of exogenous GM-CSF

Background

After traumatic skeletal muscle injury, muscle healing is often incomplete and produces extensive fibrosis. The sequence of M1 and M2 macrophage accumulation and the duration of each subtype in the injured area may help to direct the relative extent of fibrogenesis and myogenesis during healing. We hypothesized that increasing the number of M1 macrophages early after traumatic muscle injury would produce more cellular and molecular substrates for myogenesis and fewer substrates for fibrosis, leading to better muscle healing.

Methods

To test this hypothesis, we transfected skeletal muscle with a plasmid vector to transiently express GM-CSF shortly after injury to drive the polarization of macrophages towards the M1 subset. C57BL/6 mouse tibialis anterior (TA) muscles were injured by contusion and electroporated with uP-mGM, which is a plasmid vector that transiently expresses GM-CSF. Myogenesis, angiogenesis, and fibrosis were evaluated by histology, immunohistochemistry, and RT-qPCR; subpopulations of macrophages by flow cytometry; and muscle functioning by the maximum running speed on the treadmill and the recovery of muscle mass.

Results

Muscle injury increased the number of local M1-like macrophages and decreased the number of M2-like macrophages on day 4, and uP-mGM treatment enhanced this variation. uP-mGM treatment decreased TGF-β1 protein expression on day 4, and the Sirius Red-positive area decreased from 35.93 ± 15.45% (no treatment) to 2.9% ± 6.5% (p < 0.01) on day 30. uP-mGM electroporation also increased Hgf, Hif1α, and Mtor gene expression; arteriole density; and muscle fiber number during regeneration. The improvement in the quality of the muscle tissue after treatment with uP-mGM affected the increase in the TA muscle mass and the maximum running speed on a treadmill.

Conclusion

Collectively, our data show that increasing the number of M1-like macrophages immediately after traumatic muscle injury promotes muscle recovery with less fibrosis, and this can be achieved by the transient expression of GM-CSF.