Patient-specific vascularized tumor model: Blocking monocyte recruitment with multispecific antibodies targeting CCR2 and CSF-1R.

Tumor-associated inflammation drives cancer progression and therapy resistance, often linked to the infiltration of monocyte-derived tumor-associated macrophages (TAMs), which are associated with poor prognosis in various cancers. To advance immunotherapies, testing on immunocompetent pre-clinical models of human tissue is crucial. We have developed an in vitro model of microvascular networks with tumor spheroids or patient tissues to assess monocyte trafficking into tumors and evaluate immunotherapies targeting the human tumor microenvironment. Our findings demonstrate that macrophages in vascularized breast and lung tumor models can enhance monocyte recruitment via CCL7 and CCL2, mediated by CSF-1R. Additionally, a multispecific antibody targeting CSF-1R, CCR2, and neutralizing TGF-ß (CSF1R/CCR2/TGF-ß Ab) repolarizes TAMs towards an anti-tumoral M1-like phenotype, reduces monocyte chemoattractant protein secretion, and blocks monocyte migration. This antibody also inhibits monocyte recruitment in patient-specific vascularized tumor models. In summary, this vascularized tumor model recapitulates the monocyte recruitment cascade, enabling functional testing of innovative therapeutic antibodies targeting TAMs in the tumor microenvironment.

RUNX1 interacts with lncRNA SMANTIS to regulate monocytic cell functions.

Monocytes, the circulating macrophage precursors, contribute to diseases like atherosclerosis and asthma. Long non-coding RNAs (lncRNAs) have been shown to modulate the phenotype and inflammatory capacity of monocytes. We previously discovered the lncRNA SMANTIS, which contributes to cellular phenotype expression by controlling BRG1 in mesenchymal cells. Here, we report that SMANTIS is particularly highly expressed in monocytes and lost during differentiation into macrophages. Moreover, different types of myeloid leukemia presented specific SMANTIS expression patterns. Interaction studies revealed that SMANTIS binds RUNX1, a transcription factor frequently mutated in AML, primarily through its Alu-element on the RUNT domain. RNA-seq after CRISPR/Cas9-mediated deletion of SMANTIS or RUNX1 revealed an association with cell adhesion and both limited the monocyte adhesion to endothelial cells. Mechanistically, SMANTIS KO reduced RUNX1 genomic binding and altered the interaction of RUNX1 with EP300 and CBFB. Collectively, SMANTIS interacts with RUNX1 and attenuates monocyte adhesion, which might limit monocyte vascular egress.

Identification of Novel Independent Correlations between Cellular Components of the Immune System and Strain-Related Indices of Myocardial Dysfunction in CKD Patients and Kidney Transplant Recipients without Established Cardiovascular Disease.

The role of immune system components in the development of myocardial remodeling in chronic kidney disease (CKD) and kidney transplantation remains an open question. Our aim was to investigate the associations between immune cell subpopulations in the circulation of CKD patients and kidney transplant recipients (KTRs) with subclinical indices of myocardial performance. We enrolled 44 CKD patients and 38 KTRs without established cardiovascular disease. A selected panel of immune cells was measured by flow cytometry. Classical and novel strain-related indices of ventricular function were measured by speckle-tracking echocardiography at baseline and following dipyridamole infusion. In CKD patients, the left ventricular (LV) relative wall thickness correlated with the CD14++CD16- monocytes (ß = 0.447, p = 0.004), while the CD14++CD16+ monocytes were independent correlates of the global radial strain (ß = 0.351, p = 0.04). In KTRs, dipyridamole induced changes in global longitudinal strain correlated with CD14++CD16+ monocytes (ß = 0.423, p = 0.009) and CD4+ T-cells (ß = 0.403, p = 0.01). LV twist and untwist were independently correlated with the CD8+ T-cells (ß = 0.405, p = 0.02 and ß = -0.367, p = 0.03, respectively) in CKD patients, whereas the CD14++CD16+ monocytes were independent correlates of LV twist and untwist in KTRs (ß = 0.405, p = 0.02 and ß = -0.367, p = 0.03, respectively). Immune cell subsets independently correlate with left ventricular strain and torsion-related indices in CKD patients and KTRs without established CVD.

Large Extracellular Vesicles Derived from Natural Killer Cells Affect the Functions of Monocytes.

Communication between natural killer cells (NK cells) and monocytes/macrophages may play an important role in immunomodulation and regulation of inflammatory processes. The aim of this research was to investigate the impact of NK cell-derived large extracellular vesicles on monocyte function because this field is understudied. We studied how NK-cell derived large extracellular vesicles impact on THP-1 cells characteristics after coculturing: phenotype, functions were observed with flow cytometry. In this study, we demonstrated the ability of large extracellular vesicles produced by NK cells to integrate into the membranes of THP-1 cells and influence the viability, phenotype, and functional characteristics of the cells. The results obtained demonstrate the ability of large extracellular vesicles to act as an additional component in the immunomodulatory activity of NK cells in relation to monocytes.

Raman Spectroscopy of Optically Trapped Living Human T Cell Subsets and Monocytes.

In recent years, Raman spectroscopy has garnered growing interest in the field of biomedical research. It offers a non-invasive and label-free approach to defining the molecular fingerprint of immune cells. We utilized Raman spectroscopy on optically trapped immune cells to investigate their molecular compositions. While numerous immune cell types have been studied in the past, the characterization of living human CD3/CD28-stimulated T cell subsets remains incomplete. In this study, we demonstrate the capability of Raman spectroscopy to readily distinguish between naïve and stimulated CD4 and CD8 cells. Additionally, we compared these cells with monocytes and discovered remarkable similarities between stimulated T cells and monocytes. This paper contributes to expanding our knowledge of Raman spectroscopy of immune cells and serves as a launching point for future clinical applications.

Identification of SNPs and Candidate Genes Associated with Monocyte/Lymphocyte Ratio and Neutrophil/Lymphocyte Ratio in Duroc × Erhualian F2 Population.

Understanding the pig immune function is crucial for disease-resistant breeding and potentially for human health research due to shared immune system features. Immune cell ratios, like monocyte/lymphocyte ratio (MLR) and neutrophil/lymphocyte ratio (NLR), offer a more comprehensive view of immune status compared to individual cell counts. However, research on pig immune cell ratios remains limited. This study investigated MLR and NLR in a Duroc × Erhualian F2 resource population. Heritability analysis revealed high values (0.649 and 0.688 for MLR and NLR, respectively), suggesting a strong genetic component. Furthermore, we employed an ensemble-like GWAS (E-GWAS) strategy and functional annotation analysis to identify 11 MLR-associated and 6 NLR-associated candidate genes. These genes were significantly enriched in immune-related biological processes. These findings provide novel genetic markers and candidate genes associated with porcine immunity, thereby providing valuable insights for addressing biosecurity and animal welfare concerns in the pig industry.

Association of mean platelet volume (MPV), MPV/PLATELET (PLT) ratio, and lymphocyte/monocyte ratio (LMR) as poor prognostic factor in EGFR-mutant lung adenocarcinoma treated with EGFR tyrosine kinase inhibitor.

Introduction: Platelets (PLT) and host systemic inflammatory response (SIR) are known to be effective in the aggregation of cancer cells and the formation of metastasis. There are studies pointing out to the prognostic efficacy of lymphocyte-monocyte ratio (LMR) showing SIR activation and mean platelet volume (MPV) values indicating platelet activation in various cancer types. We predict that easy-to-access hemogram parameters such as MPV, MPV/PLT, and LMR can be guiding in the clinical follow-up period of patients with epidermal growth factor receptor (EGFR) positive mutation and who received EGFR, tyrosine kinase inhibitor (TKI) in the first-line treatment in predicting the progression of the disease, predicting the survival time of the patients, and evaluating the response to treatment. Materials and Methods: The study is retrospective and included patients with stage III and stage IV pulmonary adenocarcinoma with positive EGFR mutations and for whom TKI was used in the first-line treatment between January 2011 and January 2021. MPV, MPV/PLT, and LMR values of the patients were calculated before treatment. Age, sex, comorbidity, smoking history, TNM stage, metastasis localizations, EGFR mutation types, TKI treatments used in first-line treatment, and MPV, MPV/PLT, and LMR values at the 1st month of treatment were recorded. With Kaplan-Meier, six-month, one-year, three-year, and five-year survival rates, average life expectancy, and 95% confidence intervals for these periods were calculated. Variables that may affect progression and overall survival (OS) were determined by performing univariate and multivariate Cox regression analysis. Result: One hundred and two patients were included in the study. The mean age of the patients was 64.30 ± 12.6 years. Eighty-four patients were in stage IV at the time of diagnosis. The expected mean progression-free survival (PFS) period of the cases was found to be 13.3 months. The mean life expectancy of the cases was found to be 35.1 months. Web-based Cutoff Finder algorithm written in the R program (http://molpath.charite.de/cutoff) was used to determine the ideal cut points for MPV, MPV/PLT, and LMR. The cut-off values were found to be 7.55 fL for MPV, 0.251 for MPV/PLT, and 2.615 for LMR, respectively. In univariate Cox regression analysis, LMR level lower than 2.615 increased the rate of progression 1.747 times (95% confidence interval: 1.129-2.705) and the death rate 2.056 times (95% confidence interval: 1.217-3.475) (p= 0.012, p= 0.007). The mean PFS LMR cut-off value was 10.3 months, and 15.3 months, and mean OS durations were 25.1 months and 40.8 months for the groups with low and high cut-off values respectively (p= 0.011, p= 0.006 log-rank test). According to the results of multivariate Cox regression analysis, MPV/PLT < 0.251, smoking, presence of pleural and adrenal metastases, and gefitinib treatment were independent factors in determining PFS. The independent factors determining OS in multivariate Cox regression analysis were being male, platelet increase, MPV > 7.55, gefitinib treatment, and smoking. Conclusions: MPV, MPV/PLT, and LMR are potential biomarkers that can be used for the clinical follow-up of lung ADC patients receiving EGFR-TKI treatment.

Local administration of regulatory T cells promotes tissue healing.

Regulatory T cells (Tregs) are crucial immune cells for tissue repair and regeneration. However, their potential as a cell-based regenerative therapy is not yet fully understood. Here, we show that local delivery of exogenous Tregs into injured mouse bone, muscle, and skin greatly enhances tissue healing. Mechanistically, exogenous Tregs rapidly adopt an injury-specific phenotype in response to the damaged tissue microenvironment, upregulating genes involved in immunomodulation and tissue healing. We demonstrate that exogenous Tregs exert their regenerative effect by directly and indirectly modulating monocytes/macrophages (Mo/MΦ) in injured tissues, promoting their switch to an anti-inflammatory and pro-healing state via factors such as interleukin (IL)-10. Validating the key role of IL-10 in exogenous Treg-mediated repair and regeneration, the pro-healing capacity of these cells is lost when Il10 is knocked out. Additionally, exogenous Tregs reduce neutrophil and cytotoxic T cell accumulation and IFN-γ production in damaged tissues, further dampening the pro-inflammatory Mo/MΦ phenotype. Highlighting the potential of this approach, we demonstrate that allogeneic and human Tregs also promote tissue healing. Together, this study establishes exogenous Tregs as a possible universal cell-based therapy for regenerative medicine and provides key mechanistic insights that could be harnessed to develop immune cell-based therapies to enhance tissue healing.

Early transcriptomic response of innate immune cells to subcutaneous BCG vaccination of mice.

OBJECTIVES: Current data suggests that Bacille Calmette-Guerin (BCG) vaccination contributes to nonspecific enhancement of resistance to various infections. Thus, BCG vaccination induces both specific immunity against mycobacteria and non-specific "trained immunity" against various pathogens. To understand the fundamental mechanisms of "trained" immunity, studies of transcriptome changes occurring during BCG vaccination in innate immunity cells, as well as in their precursors, are necessary. Furthermore, this data possesses important significance for practical applications associated with the development of recombinant BCG strains aimed to enhance innate immunity against diverse infectious agents. DATA DESCRIPTION: We performed RNA sequencing of innate immune cells derived from murine bone marrow and spleen three days after subcutaneous BCG vaccination. Using fluorescence-activated cell sorting we obtained three cell populations for each mouse from both control and BCG vaccinated groups: bone marrow monocytes and neutrophils and splenic NK-cells. Then double-indexed cDNA libraries for Illumina sequencing from the collected samples were prepared, the resulting cDNA library mix was subjected to NovaSeq 6000 sequencing. This paper describes the collection of 24 RNA sequencing samples comprising 4 sets of immune cell populations obtained from subcutaneously BCG-vaccinated and control mice.

IL36G-producing neutrophil-like monocytes promote cachexia in cancer.

Most patients with advanced cancer develop cachexia, a multifactorial syndrome characterized by progressive skeletal muscle wasting. Despite its catastrophic impact on survival, the critical mediators responsible for cancer cachexia development remain poorly defined. Here, we show that a distinct subset of neutrophil-like monocytes, which we term cachexia-inducible monocytes (CiMs), emerges in the advanced cancer milieu and promotes skeletal muscle loss. Unbiased transcriptome analysis reveals that interleukin 36 gamma (IL36G)-producing CD38+ CiMs are induced in chronic monocytic blood cancer characterized by prominent cachexia. Notably, the emergence of CiMs and the activation of CiM-related gene signatures in monocytes are confirmed in various advanced solid cancers. Stimuli of toll-like receptor 4 signaling are responsible for the induction of CiMs. Genetic inhibition of IL36G-mediated signaling attenuates skeletal muscle loss and rescues cachexia phenotypes in advanced cancer models. These findings indicate that the IL36G-producing subset of neutrophil-like monocytes could be a potential therapeutic target in cancer cachexia.

Clearance and transport of amyloid ß by peripheral monocytes correlate with Alzheimer's disease progression.

Impaired clearance of amyloid ß (Aß) in late-onset Alzheimer's disease (AD) affects disease progression. The role of peripheral monocytes in Aß clearance from the central nervous system (CNS) is unclear. We use a flow cytometry assay to identify Aß-binding monocytes in blood, validated by confocal microscopy, Western blotting, and mass spectrometry. Flow cytometry immunophenotyping and correlation with AD biomarkers are studied in 150 participants from the AIBL study. We also examine monocytes in human cerebrospinal fluid (CSF) and their migration in an APP/PS1 mouse model. The assay reveals macrophage-like Aß-binding monocytes with high phagocytic potential in both the periphery and CNS. We find lower surface Aß levels in mild cognitive impairment (MCI) and AD-dementia patients compared to cognitively unimpaired individuals. Monocyte infiltration from blood to CSF and migration from CNS to peripheral lymph nodes and blood are observed. Here we show that Aß-binding monocytes may play a role in CNS Aß clearance, suggesting their potential as a biomarker for AD diagnosis and monitoring.

Panax notoginseng Saponins Ameliorate Gamma Radiation-Mediated Damages in Human Peripheral Blood Monocytes and Swiss Albino Mice.

In this study, the protective effects of Panax notoginseng saponins (PNS) against gamma radiation-induced DNA damage and associated physiological alterations in Swiss albino mice were investigated. Exposure to gamma radiation led to a dose-dependent increase in cytokinesis-blocked micronuclei (CBMN) double-strand DNA breaks (DSBs), dicentric aberrations (DC), formation in peripheral blood mononuclear cells. However, pretreatment with PNS at concentrations of 1, 5, and 10 µg/mL significantly attenuated the frequencies of DC and CBMN in a concentration-dependent manner. PNS administration before radiation exposure also reduced radiation-induced DSBs in BL, indicating protection against reactive oxygen species generation and DNA damage. Notably, pretreatment with PNS at 10 µg/mL prevented the overexpression of γ-H2AX, proteins associated with DNA damage response, in irradiated mice. In addition, in vivo studies showed intraperitoneal administration of PNS (25 mg/kg body weight) for 1 h before radiation exposure mitigated lipid peroxidation levels and restored antioxidant status, countering oxidative damage induced by gamma radiation. Furthermore, PNS pretreatment reversed the decrease in hemoglobin (Hb) content, white blood cell count, and red blood cell count in irradiated mice, indicating preservation of hematological parameters. Overall, PNS demonstrated an anticlastogenic effect by modulating radiation-induced DSBs and preventing oxidative damage, thus highlighting its potential as a protective agent against radiation-induced DNA damage and associated physiological alterations. Clinically, PNS will be beneficial for cancer patients undergoing radiotherapy, but their pharmacological properties and toxicity profiles need to be studied.

CD14+CD16+ monocyte transmigration across the blood-brain barrier is associated with HIV-NCI despite viral suppression.

HIV-associated neurocognitive impairment (HIV-NCI) affects 15%-50% of people with HIV (PWH), despite viral suppression with antiretroviral therapy (ART). HIV neuropathogenesis is mediated, in part, by transmigration of infected CD14+CD16+ monocytes across the blood-brain barrier (BBB) into the central nervous system (CNS). In the CNS, CD14+CD16+ monocytes contribute to infection and activation of parenchymal cells, resulting in production of neurotoxic viral and host factors that cause neuronal damage. Mechanisms by which CD14+CD16+ monocytes contribute to HIV-NCI have not been characterized in a study population of PWH on ART without contribution from confounders that affect cognition (e.g., substance use, hepatitis C virus coinfection). We assessed cognitive function, PBMC transmigration across the BBB, and neuronal health markers in a well-defined cohort of 56 PWH on ART using stringent criteria to eliminate confounding factors. We demonstrated that PWH on ART with HIV-NCI have significantly increased transmigration of their CD14+CD16+ monocytes across the BBB compared with those with normal cognition. We showed that hypertension and diabetes may be effect modifiers on the association between CD14+CD16+ monocyte transmigration and cognition. This study underscored the persistent role of CD14+CD16+ monocytes in HIV-NCI, even in PWH with viral suppression, suggesting them as potential targets for therapeutic interventions.

Activation of Toll-like receptor 2 promotes mesenchymal stem/stromal cell-mediated immunoregulation and angiostasis through AKR1C1.

Background: Mesenchymal stem/stromal cells (MSCs) maintain tissue homeostasis in response to microenvironmental perturbations. Toll-like receptors (TLRs) are key sensors for exogenous and endogenous signals produced during injury. In this study, we aimed to investigate whether TLRs affect the homeostatic functions of MSCs after injury. Methods: We examined the expression of TLR2, TLR3 and TLR4 in MSCs, and analyzed the functional significance of TLR2 activation using single-cell RNA sequencing. Additionally, we investigated the effects and mechanisms of TLR2 and its downstream activation in MSCs on the MSCs themselves, on monocytes/macrophages, and in a mouse model of sterile injury-induced inflammatory corneal angiogenesis. Results: MSCs expressed TLR2, which was upregulated by monocytes/macrophages. Activation of TLR2 in MSCs promoted their immunoregulatory and angiostatic functions in monocytes/macrophages and in mice with inflammatory corneal angiogenesis, whereas TLR2 inhibition attenuated these functions. Single-cell RNA sequencing revealed AKR1C1, a gene encoding aldo-keto reductase family 1 member C1, as the most significantly inducible gene in MSCs upon TLR2 stimulation, though its stimulation did not affect cell compositions. AKR1C1 protected MSCs against ferroptosis, increased secretion of anti-inflammatory cytokines, and enhanced their ability to drive monocytes/macrophages towards immunoregulatory phenotypes, leading to the amelioration of inflammatory corneal neovascularization in mice. Conclusion: Our findings suggest that activation of TLR2-AKR1C1 signaling in MSCs serves as an important pathway for the survival and homeostatic activities of MSCs during injury.

Nerve growth factor promote VCAM-1-dependent monocyte adhesion and M2 polarization in osteosarcoma microenvironment: Implications for larotrectinib therapy.

Osteosarcoma is the most prevalent form of primary malignant bone tumor, primarily affecting children and adolescents. The nerve growth factors (NGF) referred to as neurotrophins have been associated with cancer-induced bone pain; however, the role of NGF in osteosarcoma has yet to be elucidated. In osteosarcoma samples from the Genomic Data Commons data portal, we detected higher levels of NGF and M2 macrophage markers, but not M1 macrophage markers. In cellular experiments, NGF-stimulated osteosarcoma conditional medium was shown to facilitate macrophage polarization from the M0 to the M2 phenotype. NGF also enhanced VCAM-1-dependent monocyte adhesion within the osteosarcoma microenvironment by down-regulating miR-513c-5p levels through the FAK and c-Src cascades. In in vivo xenograft models, the overexpression of NGF was shown to enhance tumor growth, while the oral administration of the TrK inhibitor larotrectinib markedly antagonized NGF-promoted M2 macrophage expression and tumor progression. These results suggest that larotrectinib could potentially be used as a therapeutic agent aimed at mitigating NGF-mediated osteosarcoma progression.

Screening value of methylated Septin9 and lymphocyte-to-monocyte ratio in colorectal cancer.

The lymphocyte-to-monocyte ratio (LMR) is an indicator of inflammation in blood routine tests; however, little is known about its screening value in patients with colorectal cancer (CRC). The aim of this study was to explore the screening value of LMR and methylated Septin9 (mSEPT9) in CRC patients. The clinical data of 420 patients with CRC, 61 with adenomatous polyps, and 175 healthy individuals from 2018 to 2022 were retrospectively analyzed, and corresponding predictive nomograms were established. The results showed that the levels of LMR and mSEPT9 in the CRC group were significantly lower than those in the control group (P < .05). Meanwhile, the levels of LMR and mSEPT9 in right-sided CRC were significantly lower than those in left-sided CRC (P < .05). With the progression of CRC from stage I to IV, the levels of LMR and mSEPT9 also decreased gradually, and the levels of mSEPT9 in stages III and IV were significantly lower than those in stages I and II (P < .05). Receiver operating curve (ROC) results showed that mSEPT9 had the highest single diagnostic value for CRC, with an area under curve (AUC) of 0.810. The LMR with mSEPT9 combination showed the best combined diagnostic value for CRC, with AUC of 0.885. When the cutoff values of mSEPT9 and LMR were taken as 43.835 and 3.365, the sensitivity and specificity of this combination reached 82.3% and 84.6%, respectively. Our findings suggest that LMR and mSEPT9 differ in non-tumor group and CRC groups with different subtypes and stages, LMR with mSEPT9 combination can further improve sensitivity, and the novel predictive nomogram for CRC based on LMR and mSEPT9 can be further promoted.

Changes in monocyte subsets in volunteers who received an oral wild-type Salmonella Typhi challenge and reached typhoid diagnosis criteria.

An oral Controlled Human Infection Model (CHIM) with wild-type S. Typhi was re-established allowing us to explore the development of immunity. In this model, ~55% of volunteers who received the challenge reached typhoid diagnosis criteria (TD), while ~45% did not (NoTD). Intestinal macrophages are one of the first lines of defense against enteric pathogens. Most organs have self-renewing macrophages derived from tissue-resident progenitor cells seeded during the embryonic stage; however, the gut lacks these progenitors, and all intestinal macrophages are derived from circulating monocytes. After infecting gut-associated lymphoid tissues underlying microfold (M) cells, S. Typhi causes a primary bacteremia seeding organs of the reticuloendothelial system. Following days of incubation, a second bacteremia and clinical disease ensue. S. Typhi likely interacts with circulating monocytes or their progenitors in the bone marrow. We assessed changes in circulating monocytes after CHIM. The timepoints studied included 0 hours (pre-challenge) and days 1, 2, 4, 7, 9, 14, 21 and 28 after challenge. TD participants provided extra samples at the time of typhoid diagnosis, and 48-96 hours later (referred as ToD). We report changes in Classical Monocytes -CM-, Intermediate Monocytes -IM- and Non-classical Monocytes -NCM-. Changes in monocyte activation markers were identified only in TD participants and during ToD. CM and IM upregulated molecules related to interaction with bacterial antigens (TLR4, TLR5, CD36 and CD206). Of importance, CM and IM showed enhanced binding of S. Typhi. Upregulation of inflammatory molecules like TNF-α were detected, but mechanisms involved in limiting inflammation were also activated (CD163 and CD354 downregulation). CM upregulated molecules to interact/modulate cells of the adaptive immunity, including T cells (HLA-DR, CD274 and CD86) and B cells (CD257). Both CM and IM showed potential to migrate to the gut as integrin α4ß7 was upregulated. Unsupervised analysis revealed 7 dynamic cell clusters. Five of these belonged to CM showing that this is the main population activated during ToD. Overall, we provide new insights into the changes that diverse circulating monocyte subsets undergo after typhoid diagnosis, which might be important to control this disease since these cells will ultimately become intestinal macrophages once they reach the gut.

Innate immunity in peripheral tissues is differentially impaired under normal and endotoxic conditions in aging.

Chronic low-grade inflammation is a hallmark of aging, aka "inflammaging", which is linked to a wide range of age-associated diseases. Immune dysfunction increases disease susceptibility, and increases morbidity and mortality of aging. Innate immune cells, including monocytes, macrophages and neutrophils, are the first responders of host defense and the key mediators of various metabolic and inflammatory insults. Currently, the understanding of innate immune programming in aging is largely fragmented. Here we investigated the phenotypic and functional properties of innate immune cells in various peripheral tissues of young and aged mice under normal and endotoxic conditions. Under the steady state, aged mice showed elevated pro-inflammatory monocytes/macrophages in peripheral blood, adipose tissue, liver, and colon. Under lipopolysaccharide (LPS)-induced inflammatory state, the innate immune cells of aged mice showed a different response to LPS stimulus than that of young mice. LPS-induced immune responses displayed differential profiles in different tissues and cell types. In the peripheral blood, when responding to LPS, the aged mice showed higher neutrophils, but lower pro-inflammatory monocytes than that in young mice. In the peritoneal fluid, while young mice exhibited significantly elevated pro-inflammatory neutrophils and macrophages in response to LPS, aged mice exhibited decreased pro-inflammatory neutrophils and variable cytokine responses in macrophages. In the adipose tissue, LPS induced less infiltrated neutrophils but more infiltrated macrophages in old mice than young mice. In the liver, aged mice showed a more robust increase of pro-inflammatory macrophages compared to that in young mice under LPS stimulation. In colon, macrophages showed relatively mild response to LPS in both young and old mice. We have further tested bone-marrow derived macrophages (BMDM) from young and aged mice, we found that BMDM from aged mice have impaired polarization, displaying higher expression of pro-inflammatory markers than those from young mice. These data collectively suggest that innate immunity in peripheral tissues is impaired in aging, and the dysregulation of immunity is tissue- and cell-dependent. Our findings in the rodent model underscore the complexity of aging immunity. Further investigation is needed to determine whether the immune profile observed in aged mice is applicable in age-associated diseases in humans.

Development and characterization of dendritic cell internalization and activation assays contributing to the immunogenicity risk evaluation of biotherapeutics.

Introduction: Immunogenicity refers to the ability of a substance, such as a therapeutic drug, to elicit an immune response. While beneficial in vaccine development, undesirable immunogenicity can compromise the safety and efficacy of therapeutic proteins by inducing anti-drug antibodies (ADAs). These ADAs can reduce drug bioavailability and alter pharmacokinetics, necessitating comprehensive immunogenicity risk assessments starting at early stages of drug development. Given the complexity of immunogenicity, an integrated approach is essential, as no single assay can universally recapitulate the immune response leading to the formation of anti-drug antibodies. Methods: To better understand the Dendritic Cell (DC) contribution to immunogenicity, we developed two flow cytometry-based assays: the DC internalization assay and the DC activation assay. Monocyte-derived dendritic cells (moDCs) were generated from peripheral blood mononuclear cells (PBMCs) and differentiated over a five-day period. The internalization assay measured the accumulation rate of therapeutic antibodies within moDCs, while the activation assay assessed the expression of DC activation markers such as CD40, CD80, CD86, CD83, and DC-SIGN (CD209). To characterize these two assays further, we used a set of marketed therapeutic antibodies. Results: The study highlights that moDCs differentiated for 5 days from freshly isolated monocytes were more prone to respond to external stimuli. The internalization assay has been shown to be highly sensitive to the molecule tested, allowing the use of only 4 donors to detect small but significant differences. We also demonstrated that therapeutic antibodies were efficiently taken up by moDCs, with a strong correlation with their peptide presentation on MHC-II. On the other hand, by monitoring DC activation through a limited set of activation markers including CD40, CD83, and DC-SIGN, the DC activation assay has the potential to compare a series of compounds. These two assays provide a more comprehensive understanding of DC function in the context of immunogenicity, highlighting the importance of both internalization and activation processes in ADA development. Discussion: The DC internalization and activation assays described here address key gaps in existing immunogenicity assessment methods by providing specific and reliable measures of DC function. The assays enhance our ability to pre-clinically evaluate the immunogenic potential of biotherapeutics, thereby improving their safety and efficacy. Future work should focus on further validating these assays and integrating them into a holistic immunogenicity risk assessment framework.

Iron-depleting nutritional immunity controls extracellular bacterial replication in Legionella pneumophila infections.

The accidental human pathogen Legionella pneumophila (Lp) is the etiological agent for a severe atypical pneumonia known as Legionnaires' disease. In human infections and animal models of disease alveolar macrophages are the primary cellular niche that supports bacterial replication within a unique intracellular membrane-bound organelle. The Dot/Icm apparatus-a type IV secretion system that translocates ~300 bacterial proteins within the cytosol of the infected cell-is a central virulence factor required for intracellular growth. Mutant strains lacking functional Dot/Icm apparatus are transported to and degraded within the lysosomes of infected macrophages. The early foundational work from Dr. Horwitz's group unequivocally established that Legionella does not replicate extracellularly during infection-a phenomenon well supported by experimental evidence for four decades. Our data challenges this paradigm by demonstrating that macrophages and monocytes provide the necessary nutrients and support robust Legionella extracellular replication. We show that the previously reported lack of Lp extracellular replication is not a bacteria intrinsic feature but rather a result of robust restriction by serum-derived nutritional immunity factors. Specifically, the host iron-sequestering protein Transferrin is identified here as a critical suppressor of Lp extracellular replication in an iron-dependent manner. In iron-overload conditions or in the absence of Transferrin, Lp bypasses growth restriction by IFNγ-primed macrophages though extracellular replication. It is well established that certain risk factors associated with development of Legionnaires' disease, such as smoking, produce a chronic pulmonary environment of iron-overload. Our work indicates that iron-overload could be an important determinant of severe infection by allowing Lp to overcome nutritional immunity and replicate extracellularly, which in turn would circumvent intracellular cell intrinsic host defenses. Thus, we provide evidence for nutritional immunity as a key underappreciated host defense mechanism in Legionella pathogenesis.