Melanoma has one of the highest propensities to metastasize to the brain, and despite major advances with immune checkpoint inhibitors, brain metastases remain a leading cause of morbidity and mortality. The biological mechanisms governing brain colonization, immune evasion, and resistance to therapy are incompletely understood. This review summarizes recent advances in the understanding of the tumor microenvironment and signaling pathways involved in melanoma brain metastasis, with emphasis on mechanisms that may provide novel therapeutic opportunities. We performed a review of preclinical and clinical studies investigating molecular pathways, immune-cell interactions, and metabolic programs associated with melanoma brain metastasis and response to immunotherapy. Emerging evidence identifies enhancer of zeste homolog 2 (EZH2) phosphorylation by Src kinase as a key driver of brain metastasis through granulocyte colony-stimulating factor (G-CSF) production and recruitment of immunosuppressive neutrophils. Microglia and tumor-associated macrophages constitute major components of the brain metastatic microenvironment and actively support tumor progression. Spleen tyrosine kinase (Syk) signaling contributes to microglial activation and immune-related neurotoxicity during anti-programmed death 1 (PD-1) therapy. Mitochondrial dysfunction, including alterations in mitochondrial contact site and cristae organizing system (MICOS) complex components such as Mic19 and Mic60, promotes innate immune signaling through cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) and TANK-binding kinase 1 (TBK1). TBK1 emerges as a central regulator linking neuroinflammation, microglial activation, metastatic progression, and therapeutic resistance. In addition, metabolic reprogramming mediated by tectonic family member 1 (TCTN1) and carnitine palmitoyltransferase 1A (CPT1A) enhances fatty acid oxidation and promotes melanoma metastasis. These pathways may represent actionable targets that complement immune checkpoint blockade. Melanoma brain metastasis is driven by complex interactions between tumor cells, neutrophils, microglia, and mitochondrial signaling networks. Src-EZH2, TBK1-dependent inflammatory pathways, and TCTN1/CPT1A-mediated metabolic reprogramming are emerging biomarkers and therapeutic targets. Integrating these approaches with anti-PD-1 and anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) therapies may improve disease control, overcome resistance, and reduce immune-related adverse events in patients with melanoma brain metastases.

Elderly AML (Acute Myeloid Leukemia) patients exhibit increased mortality owing to chemotherapy-induced myelosuppression. Umbilical cord blood (UCB) contains hematopoietic stem/progenitor cells and a spectrum of regenerative cytokines that actively promote hematopoietic regeneration. We investigated whether umbilical cord blood (UCB) infusion enhances hematopoietic recovery in elderly AML patients who experience chemotherapy-induced myelosuppression during post-chemotherapy supportive care.

Inflammation contributes to primary antiphospholipid syndrome (PAPS) pathogenesis, but cytokine profiles and associated thrombotic phenotypes remain incompletely defined. A panel of 20 cytokines, chemokines and endothelial activation markers was analysed in 37 PAPS patients on stable anticoagulation and 12 healthy controls (HC). We compared concentrations between groups and performed unsupervised hierarchical clustering and principal component analysis (PCA) to identify inflammatory subgroups. Compared with HC, patients with PAPS exhibited significantly elevated levels of 14/20 analytes: granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-γ, interleukin (IL)-1α, IL-1β, IL-6, IL-10, IL-12p70, IL-13, IL-17a, tumour necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1), P-selectin and macrophage inflammatory protein-1β (MIP1β) (all p < 0.05). Unsupervised clustering identified three inflammatory antiphospholipid syndrome (APS) subgroups distinct from HC. A core cytokine signature comprising GM-CSF, IL-6, IL-10, IL-12p70, IL-13 and TNF-α was elevated across all APS clusters. One cluster, enriched for arterial thrombosis, demonstrated a more pronounced inflammatory phenotype, with increased IFN-α. Comparison of phenotypes showed significantly higher concentrations of GM-CSF, IFN-α, IL-1α, IL-4, IL-6, IL-10, IL-17a and TNF-α in arterial versus venous thrombosis. Our findings demonstrate widespread cytokine dysregulation and distinct inflammatory subgroups in PAPS, with arterial thrombosis showing stronger inflammation than venous thrombosis, supporting divergent thrombo-inflammatory mechanisms and potential precision immunomodulatory therapeutic targets.

Group A Streptococcus (GAS) infections cause neuropsychiatric complications in children, but the mechanisms linking peripheral infection to brain dysfunction remain unclear. Using mouse genetics, single-cell RNA sequencing, and spatial transcriptomics, we show that GAS infections induce inflammatory transcriptional programs in microglia and brain endothelial cells (BECs), accompanied by loss of blood-brain barrier (BBB) gene expression in female mice. Spatial transcriptomic analyses reveal that GAS-responsive microglia localize near infiltrating CD4[+] T cells. Several microglial chemokines induced in mice are elevated in sera from affected patients. Deletion of GM-CSF in CD4[+] T cells partially reduces microglial chemokine gene expression, without restoring BBB integrity. In contrast, IL-17A neutralization partially rescues BBB transcriptional changes, but not BBB dysfunction, and reduces microglial chemokine expression. Microglia-specific deletion of IL-17 receptor A partially restores BBB integrity after GAS infections. Our findings identify microglial IL-17A-IL17RA signaling as a potential mediator of BBB dysfunction and neuroinflammation after GAS infections.

Autologous stem cell transplantation (ASCT) following high dose chemotherapy is used for management of various pediatric malignancies, and plerixafor used in conjunction with GCSF is used to mobilize hematopoietic stem cells (HSCs) from bone marrow to peripheral blood for collection. While the efficacy and safety of plerixafor is established in adults, data for its use in children are limited. Factors influencing plerixafor response in pediatric patients have not been extensively investigated. This retrospective study aimed to identify predictors of response to plerixafor in pediatric patients undergoing ASCT. This single-center, retrospective study evaluated 22 pediatric patients who underwent mobilization with granulocyte colony-stimulating factor (GCSF) and plerixafor for ASCT between 2017 and 2024. Patient factors such as age, sex, baseline platelet count, marrow involvement, comorbidities, and malnutrition were recorded. Baseline platelet counts were measured on Day - 1 (the day prior to plerixafor administration). Treatment factors, including exposure to radiotherapy, anthracyclines, and multiple lines of chemotherapy, were also considered. CD34 + cell counts were measured before plerixafor administration and after harvest, and response was assessed by percentage, absolute, and log percent increase in CD34 counts. Regression analysis was done to look at the effect of various factors on response to plerixafor. The study found a significant increase in CD34 counts after plerixafor administration, with a median log percent increase of 3.54 (3.24-3.61). While age and malnutrition showed a significant correlation with log percent CD34 increase (p = 0.012 and p = 0.021, respectively), multivariate regression analysis revealed that only baseline platelet count achieved statistical significance as a predictor of response to plerixafor (p = 0.046). Pre-harvest baseline platelet count is an independent predictor of response to plerixafor in pediatric patients undergoing autologous stem cell transplantation. This finding suggests that baseline platelet counts can help predict the effectiveness of plerixafor-mediated stem cell mobilization in this patient population. Further larger prospective studies are warranted to validate these findings and identify additional factors influencing plerixafor response in pediatric patients.

The use of recombinant human granulocyte-colony stimulating factor (G-CSF) is an uncommon aetiology for acute kidney injury in cancer patients. Several patterns of renal injury due to G-CSF have been discussed in the literature. Here, we present a case of a 48-year-old man with monoclonal gammopathy of renal significance who received filgrastim for planned autologous stem cell transplantation and developed acute kidney injury presenting as crescentic glomerulonephritis. The patient was treated with steroids, plasmapheresis, and cyclophosphamide. He attained complete recovery and proceeded with stem cell transplantation. We conducted an extensive review of the literature on the subject, which revealed that 10 of the 18 biopsy-proven cases of G-CSF-induced renal injury presented as crescentic glomerulonephritis. When G-CSF is administered to patients with an underlying renal pathology (usually autoimmune or monoclonal in aetiology), the migration and degranulation of activated neutrophils in the glomerular microenvironment in large numbers results in glomerular basement membrane rupture and crescent formation. Timely renal biopsy and aggressive initiation of treatment aid in attaining renal recovery and a favourable prognosis in cancer patients.

Hypoxia upregulated 1 (HYOU1) is a stress-inducible ER chaperone. We investigated 2 unrelated patients carrying biallelic HYOU1 variants and presenting with primary immunodeficiency. Patient 1, homozygous for p.Pro444His, displayed failure to thrive, hypoglycemia, B cell lymphopenia, and neutropenia. Patient 2, compound heterozygous for p.Arg262Gln and p.Pro757_Glu758insAla, exhibited recurrent infections, enteropathy, and hypogammaglobulinemia. In Patient 1, while HYOU1 transcription was preserved, the protein was severely reduced. Tunicamycin treatment of dermal fibroblasts showed a blunted unfolded protein response and defective induction of ER stress-responsive genes. Immunophenotyping showed near-absence of circulating B cells, and single-cell RNA sequencing of bone marrow identified an arrest at the pro-B cell stage. Neutrophils displayed hypogranulation and dysregulated IFN- and apoptosis-associated transcriptional signatures, unresponsive to G-CSF. HYOU1 deficiency hence results in ER stress-induced proteostasis failure that simultaneously impairs adaptive immunity through B cell developmental arrest and innate immunity through neutrophil dysfunction and IFN pathway imbalance. This work expands the spectrum of HYOU1 deficiency and further identifies ER proteostasis as a central determinant of immune homeostasis.

Hypoxia upregulated 1 (HYOU1) is a stress-inducible ER chaperone. We investigated 2 unrelated patients carrying biallelic HYOU1 variants and presenting with primary immunodeficiency. Patient 1, homozygous for p.Pro444His, displayed failure to thrive, hypoglycemia, B cell lymphopenia, and neutropenia. Patient 2, compound heterozygous for p.Arg262Gln and p.Pro757_Glu758insAla, exhibited recurrent infections, enteropathy, and hypogammaglobulinemia. In Patient 1, while HYOU1 transcription was preserved, the protein was severely reduced. Tunicamycin treatment of dermal fibroblasts showed a blunted unfolded protein response and defective induction of ER stress-responsive genes. Immunophenotyping showed near-absence of circulating B cells, and single-cell RNA sequencing of bone marrow identified an arrest at the pro-B cell stage. Neutrophils displayed hypogranulation and dysregulated IFN- and apoptosis-associated transcriptional signatures, unresponsive to G-CSF. HYOU1 deficiency hence results in ER stress-induced proteostasis failure that simultaneously impairs adaptive immunity through B cell developmental arrest and innate immunity through neutrophil dysfunction and IFN pathway imbalance. This work expands the spectrum of HYOU1 deficiency and further identifies ER proteostasis as a central determinant of immune homeostasis.

Noninvasive detection of microglia is crucial for monitoring their spatiotemporal dynamics and facilitating early medical intervention during the prodromal stages of these neuroinflammatory diseases. Colony-stimulating factor 1 receptor (CSF1R) is a promising imaging biomarker for microglia in neuroinflammation. However, currently developed CSF1R-targeted probes lack [18F]-labeled variants, and their stability, sensitivity, and specificity are all suboptimal to some extent. In our study, based on pyrrolopyrimidines(a distinct structure of CSF1R inhibitors), we developed the [18F]-labeled CSF1R-targeted probe-18F-FPPA (6-(4-(2-(2-(2-(fluoro-18F)ethoxy)ethoxy)ethoxy)phenyl)-N-methyl-N-(3-methylbenzyl)-7H-pyrrolo[2,3-d]pyrimidin-4-amine).18F-FPPA was synthesized with a radiochemical yield of 4-7%, molar activity of 30-70 GBq/μmol, and radiochemical purity exceeding 99%, which possesses excellent physicochemical properties, rapid blood pharmacokinetics (T1/2α = 2.50 min, T1/2β = 32.4 min), favorable invitro and in vivo stability, and a clear metabolic pathway via dual hepatobiliary and renal excretion. A marked uptake of 18F-FPPA was observed at the LPS injection site in the LPS group at 30-40 min postinjection. A decreased uptake also was observed in cold 19F-FPPA, BLZ945, and PLX3397 blocking groups (P < 0.05), and no obvious increase in the group of intraperitoneal injection of cyclosporine A (P > 0.05). The in vivo imaging and immunohistochemical results confirmed the specific uptake of 18F-FPPA by targeting CSF1R on microglia in inflamed tissues. Overall, our findings demonstrated that 18F-FPPA had great potential as a promising tracer for the imaging of neuroinflammatory diseases, while its unique binding profile also provides insights into CSF1R-targeted ligand development.

Triple-negative breast cancer (TNBC) responds poorly to immunotherapy, in part because its hyaluronic acid (HA)-rich and immunosuppressive tumor microenvironment restricts drug penetration and antitumor immune activation. Here, we developed an injectable alginate hydrogel platform (ICG-LNP@ALG-H) for localized co-delivery of hyaluronidase (HAase) and indocyanine green (ICG)-functionalized lipid nanoparticles (LNPs) carrying messenger RNA (mRNA) encoding interleukin-12 (IL-12) and granulocyte-macrophage colony-stimulating factor (GM-CSF). After administration into the postoperative tumor bed, the hydrogel formed an in situ depot that enabled sustained local retention and release. HAase degraded the HA-rich stromal matrix to enhance nanoparticle penetration, while near-infrared (NIR)-activated ICG generated reactive oxygen species through a photodynamic effect, promoting endosomal escape and improving intracellular mRNA delivery and cytokine expression. This platform integrated stromal remodeling, photoactivated intracellular delivery, and local immunostimulation in a single controlled-release system. In a postoperative 4 T1 TNBC recurrence model, ICG-LNP@ALG-H reduced local recurrence and elicited coordinated local and systemic immune responses, as indicated by enhanced intratumoral IL-12 expression and CD8+ T-cell infiltration, together with increased splenic NK-cell frequency, dendritic-cell maturation, and M1-like macrophage polarization. Short-term safety assessments revealed no overt abnormalities under the tested conditions. These results show that localized delivery of matrix-remodeling and immunostimulatory cargoes can address both stromal and intracellular barriers to mRNA therapy, supporting ICG-LNP@ALG-H as a locoregional controlled-release strategy for postoperative immunotherapy of stromal-rich solid tumors.

Despite the widespread use of prophylactic vaccines, Human papillomavirus (HPV) related cancers persist as a substantial global health burden, highlighting the high demand for effective therapeutics. Signal peptide (SP) and major histocompatibility complex (MHC) class I trafficking domain (MITD) have been utilized in HPV messenger RNA (mRNA) therapeutic vaccines to improve MHC class I and II presentation. However, how antigen-processing modules (ubiquitin [Ub], SP-MITD, lysosome-associated membrane protein [LAMP]) and immune stimulators (granulocyte-macrophage colony-stimulating factor [GM-CSF], stimulator of interferon [IFN] genes [STING], CD4[+] T cell epitopes) functionally interact within a single mRNA vaccine remains unexplored. Here, we identified an optimized structural configuration for HPV16 mRNA therapeutic vaccines that exhibited superior efficacy within our TC-1 murine models under the present conditions: SP-MITD-containing constructs were associated with greater anti-tumor efficacy than Ub-containing constructs; two distinct immune modulators-GM-CSF and STING-elicited comparable magnitudes of IFN-γ responses when integrated into the SP-MITD backbone; pan-HLA-DR binding epitope (PADRE) was selected among a panel of CD4[+] T cell epitopes based on IFN-γ responses in PBMCs and previous clinical experiences, and showed a trend toward improved anti-tumor activity when added to the SP-MITD-GM-SCF construct. These findings guided the development of ABO-208, a lipid nanoparticle-encapsulated therapeutic mRNA vaccine targeting HPV16 E6-E7, incorporating SP-MITD, GM-CSF and PADRE. In preclinical models, ABO-208 elicited robust antigen-specific T cell responses and effectively inhibited both small (∼50 mm[3]) and large (∼420 mm[3]) tumors in TC-1 murine models. Furthermore, ABO-208 showed prophylactic potential, making it a promising candidate for HPV-related treatment and prevention under the current experimental setup. This potent efficacy highlights the potential value of the optimized structural integration evaluated in this study.