Identification of the haemoglobin scavenger receptor

Erythroblastic island: the niche for erythroid terminal differentiation and beyond

The erythroblastic island (EBI) is a multicellular structure defined by the presence of 1 or 2 central macrophages surrounded by at least 3 erythroblasts. EBIs were initially proposed as a specialized microenvironment exclusively for erythroid terminal differentiation. Recent advancements in techniques such as lineage tracing mouse models, imaging flow cytometry, and single-cell RNA sequencing, accumulating evidence has provided novel insights that challenge this conventional view. Notably, the erythropoietin receptor has been identified as a novel marker for EBI macrophages. Additionally, neutrophils have been identified as novel cellular components of EBIs, raising the intriguing hypothesis that EBIs may support other hematopoietic lineage cells as well. Beyond the diverse cellular components of various hematopoietic lineages, even within the erythroid lineage, an immune-prone erythroblast subpopulation has been reported, although it remains unclear whether and how these immune-prone erythroblasts mature in EBIs. These observations indicate that EBIs are a heterogeneous population. In this review, we summarize the most recent findings on EBIs, discuss their potential immune functions, and provide a perspective for future investigations.

Red blood cells-derived components as biomimetic functional materials: Matching versatile delivery strategies based on structure and function

Red blood cells (RBCs), often referred to as "intelligent delivery systems", can serve as biological or hybrid drug carriers due to their inherent advantages and characteristics. This innovative approach has the potential to enhance biocompatibility, pharmacokinetics, and provide targeting properties for drugs. By leveraging the unique structure and contents of RBCs, drug-loading pathways can be meticulously designed to align with these distinctive features. This review article primarily discusses the drug delivery strategies and their applications that are informed by the structural and functional properties of the main components of RBCs, including living RBCs, membranes, hollow RBCs, and hemoglobin. Overall, this review article would assist efforts to make better decisions on optimization and rational utilization of RBCs derivatives-based drug delivery strategies for the future direction in clinical translation.

Haptoglobin phenotype: A germline risk factor for malignant pleural mesothelioma? A case-control study

PURPOSE

The pathogenesis of malignant pleural mesothelioma (MPM) is linked to asbestos-induced chronic inflammation, oxidant formation, hemolysis and subsequent hemoglobin (Hb) release, potentiating oxidative injury. Haptoglobin (Hp) serves as a major antioxidant by binding free Hb in order to prevent its harmful effects. Dependent on the Hp-phenotype, this complexing can be divergent, leading to additional formation of reactive oxygen species (ROS) above those directly induced by asbestos or released by inflammatory cells. In order to determine the Hp-phenotype as a risk factor in MPM, this case-control study compared the Hp-phenotype distribution in MPM patients with asymptomatic persons with former occupational asbestos exposure (AEx) and controls from a European population.

MATERIALS AND METHODS

Hp-phenotyping was done on serum samples of 118 MPM patients and 96 AEx subjects by starch gel electrophoresis. The frequencies of Hp phenotypes (Hp 1-1, Hp 2-1 and Hp 2-2) and alleles (Hp1, Hp2) were compared with those from 918 healthy control subjects.

RESULTS

The Hp 1-1 phenotype was overrepresented in MPM patients compared to AEx persons (P = 0.001) and healthy controls (P = 0.005). The relative risk for developing MPM when having the Hp 1-1 phenotype was 3.05 (1.47-6.34) for AEx subjects and 1.74 (1.19-2.54) for healthy controls compared to other phenotypes.

CONCLUSION

Our results indicate an important role of the Hp-phenotype in MPM pathogenesis suggesting that Hp 1-1 phenotypic persons are more prone for MPM development. Apart from the asbestos-induced radical formation, this finding confirms the role of oxidative stress in cancer development.

Prognostic value of CD163+ macrophages in solid tumor malignancies: A scoping review

Tumor-associated macrophages (TAMs) play crucial roles in development and progression of malignant diseases. Notably, CD163+ TAMs likely perform specific pro-tumorigenic functions, suggesting that this subset may serve as both prognostic biomarkers and targets for future anti-cancer therapy. We conducted a scoping review to map the current knowledge on the prognostic role of CD163+ TAMs in the five most lethal cancers worldwide: Lung, colorectal, gastric, liver, and breast cancer. For all cancer types, most studies showed that high tumoral presence of CD163+ cells was associated with poor patient outcome, and this association was more frequently observed when CD163+ cells were measured at the tumor periphery compared to more central parts of the tumor. These results support that CD163+ TAMs represent a biomarker of poor patient outcome across a variety of solid tumors, and highlight the relevance of further investigations of CD163+ TAMs as targets of future immunotherapies.

New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) has a restricted host specificity, primarily infecting porcine macrophages. Notably, an exception to such macrophage-restricted tropism has been observed in sexually active boars, where the virus infects and induces apoptosis in the germinal epithelium, resulting in viral dissemination in the ejaculate. Whether this phenomenon occurs in prepubertal animals remains unclear. In this study, we isolated spermatogonia stem cells (SSCs) from neonatal pigs and cultured them in vitro. These SSC cultures formed morula-like colonies, exhibited alkaline phosphatase activity-a characteristic of stem cells-and expressed protein gene product 9.5, a marker of SSCs. Notably, the SSC cultures supported PRRSV replication with kinetics similar to that observed in porcine alveolar macrophages. To assess the testicular tropism of PRRSV in prepuberal animals, 28-day-old male pigs were infected with a virulent PRRSV strain. Testicular tissues were sequentially analyzed using a combination of in situ hybridization for PRRSV RNA and immunohistochemistry for specific cellular markers. Unlike in sexually active boars, PRRSV did not infect the spermatogonia cells within the seminiferous tubules of prepubertal pigs. Instead, the virus primarily infected macrophages and myoid cells located in the interstitium and peritubular areas. It appeared that the anatomical separation of spermatogonia from the basal membrane of the seminiferous tubules in prepubertal pigs prevents these cells from being infected by PRRSV. Overall, our findings offer valuable insights into the age-dependent testicular tropism of PRRSV.IMPORTANCEContaminated boar semen used in artificial insemination has significantly contributed to the global spread of porcine reproductive and respiratory syndrome virus (PRRSV), a virus that typically infects only cells within the monocyte and macrophage lineages. Our study reveals that spermatogonia stem cells (SSCs) from neonatal piglets are also susceptible to PRRSV, suggesting that non-macrophage cells can be infected by the virus. However, despite this susceptibility, PRRSV-infected cells were not found in the seminiferous tubules of prepubertal male pigs inoculated with a virulent PRRSV strain. This contrasts with sexually mature boars, where PRRSV-infected cells were prominently observed within the seminiferous tubules. The discrepancy is likely due to anatomical differences between the seminiferous tubules of sexually mature boars and prepubertal pigs. These findings provide new insights into PRRSV pathogenesis. Additionally, the ex vivo SSC culture provides a valuable model for identifying new viral receptors necessary for PRRSV infection and for investigating the virus's impact on spermatogenesis.

New insights on extramedullary granulopoiesis and neutrophil heterogeneity in the spleen and its importance in disease

Neutrophils are traditionally viewed as uncomplicated exterminators that arrive quickly at sites of infection, kill pathogens, and then expire. However, recent studies employing modern transcriptomics coupled with novel imaging modalities have discovered that neutrophils exhibit significant heterogeneity within organs and have complex functional roles ranging from tissue homeostasis to cancer and chronic pathologies. This has revised the view that neutrophils are simplistic butchers, and there has been a resurgent interest in neutrophils. The spleen was described as a granulopoietic organ more than 4 decades ago, and studies indicate that neutrophils are briefly retained in the spleen before returning to circulation after proliferation. Transcriptomic studies have discovered that splenic neutrophils are heterogeneous and distinct compared with those in blood. This suggests that a unique hematopoietic niche exists in the splenic microenvironment, i.e., capable of programming neutrophils in the spleen. During severe systemic inflammation with an increased need of neutrophils, the spleen can adapt by producing neutrophils through emergency granulopoiesis. In this review, we describe the structure and microanatomy of the spleen and examine how cells within the splenic microenvironment help to regulate splenic granulopoiesis. A focus is placed on exploring the increase in splenic granulopoiesis to meet host needs during infection and inflammation. Emerging technologies such as single-cell RNA sequencing, which provide valuable insight into splenic neutrophil development and heterogeneity, are also discussed. Finally, we examine how tumors subvert this natural pathway in the spleen to generate granulocytic suppressor cells to promote tumor growth.

Single-cell transcriptome analysis reveals atypical monocytes circulating ahead of acute graft-versus-host disease clinical onset

Acute graft-versus-host disease (aGVHD) represents the rejection of the recipient's skin, gut, and liver tissues of an allogeneic hematopoietic stem cell transplantation (HSCT) by the donor T cells. The onset of aGVHD is often rapid and its evolution is unpredictable. We undertook the single-cell RNA sequencing of peripheral blood mononuclear cells collected before aGVHD clinical onset in 3 patients and from 1 patient afterward. We used 4 HSCT recipients who remained free of aGVHD as controls. This analysis unveiled the presence of particular subpopulations of circulating monocytes and cytotoxic T cells (CTLs) in pre-aGVHD samples up to 18 d before clinical disease. These pre-aGVHD monocytes were characterized by an upregulation of the M2 polarity marker CD163 and the transmembrane protein SIGLEC1/CD169. At the same time, their CTL counterparts stood out for the upregulation of the CXCL10 receptor CXCR3 and the antigenic stimulation marker CD70. The occurrence of CD163/SIGLEC1 co-expressing monocytes upstream of aGVHD onset was validated using transcriptomic data from an independent cohort and by flow cytometry in additional blood samples. These findings point to potential early diagnostic tools and preventive therapeutic strategies for aGVHD.

Splenic red pulp macrophages eliminate the liver-resistant Streptococcus pneumoniae from the blood circulation of mice

Invasive infections by encapsulated bacteria are the major cause of human morbidity and mortality. The liver resident macrophages, Kupffer cells, form the hepatic firewall to clear many encapsulated bacteria in the blood circulation but fail to control certain high-virulence capsule types. Here we report that the spleen is the backup immune organ to clear the liver-resistant serotypes of Streptococcus pneumoniae (pneumococcus), a leading human pathogen. Asplenic mice failed to control the growth of the liver-resistant pneumococci in the blood circulation. Immunologic and genetic analyses identified splenic red pulp (RP) macrophages as the major phagocytes for bacterial clearance. Furthermore, the plasma natural antibodies against the cell wall phosphocholine and the complement system were necessary for RP macrophage-mediated immunity. These findings have provided a conceptual framework for the innate defense against blood bacterial infections, a mechanistic explanation for the hyper-susceptibility of asplenic individuals to S. pneumoniae, and a proof of concept for developing vaccines and therapeutic antibodies against encapsulated pathogens.

Selinexor's Immunomodulatory Impact in Advancing Multiple Myeloma Treatment

Despite the major advancements in the repertoire for multiple myeloma (MM) treatment, this disease remains a chronically progressive plasma cell malignancy. Drug resistance and high relapse rates complicate the extended treatment strategies. However, the tumor microenvironment (TME) in MM is decisive for the success of a therapy or relapse. Aiming to improve the outcome of relapsed and refractory MM patients, Selinexor has entered the drug arsenal of myeloma therapy through the implementation of a novel therapeutic approach by selectively inhibiting the nuclear export receptor Exportin-1 (XPO1). Selinexor leads to the inactivation of cancer-related proteins and induces apoptosis by disrupting the nucleocytoplasmic flow in myeloma cells. While this drug is selectively cytotoxic to neoplastic cells, Selinexor's immunomodulatory impact on the TME is currently being investigated. The aim of this review was to elucidate Selinexor's capacity to influence the cell interaction network of the TME from an immunological perspective. Deciphering the complex interplay of highly plastic immune cells provides a contribution to the molecular-biological exploration of disease initiation and progression in MM. Unraveling the novel therapeutic targets of the immunological TME and evaluating the advanced immunotherapeutic regimens implementing Selinexor will shape the future directions of immune-oncotherapy in MM.

Total bilirubin as a marker for hemolysis and outcome in patients with severe ARDS treated with veno-venous ECMO

BACKGROUND

Hemolysis is a common complication in critically ill patients with sepsis, acute respiratory distress syndrome (ARDS) or therapy with extracorporeal membrane oxygenation (ECMO). Heme degradation product bilirubin might accumulate in conditions of significant hemolysis. In patients with ARDS and therapy with veno-venous ECMO (vvECMO), the prognostic potential of elevated initial total bilirubin (tBili) was investigated.

METHODS

Retrospective analysis of patients with ARDS and vvECMO-therapy (n = 327) admitted to a tertiary ARDS center. A tBili cut-off value was determined by binary recursive partitioning. Baseline characteristics were compared and relevant variables were included in a multivariate logistic regression model with backward variable selection. Primary endpoint was survival within 28 days analyzed with Kaplan-Meier-curves and cox regression. Secondary endpoints included failure free composites for organ dysfunction, renal replacement therapy (RRT), vasopressor therapy and ECMO within 28 days and were compared using competing risk regression analysis.

RESULTS

A cut-off value of 3.6mg/dl divided the cohort for ICU mortality (tBili ≤ 3.6mg/dl: 46% (n = 273) vs. tBili > 3.6mg/dl: 78% (n = 54), p < 0.001). The group with tBili > 3.6mg/dl showed a higher 28-day mortality (HR 3.03 [95%CI 2.07-4.43], p < 0.001) and significantly lower chances of successful recovery from organ dysfunction (subdistribution hazard ratio (SHR) 0.29 [0.13-0.66], p < 0.001), RRT (SHR 0.34 [0.14-0.85], p = 0.02), and ECMO (SHR 0.46 [0.25-0.86], p = 0.015) compared to the group with tBili ≤ 3.6mg/dl. Recovery from vasopressor therapy did not differ between groups (SHR 0.63 [0.32-1.24], p = 0.18).

CONCLUSION

Patients with ARDS, vvECMO-therapy and tBili > 3.6mg/dl had a higher mortality and lower chances for recovery from organ dysfunction, RRT, and ECMO within 28 days. The tBili-cut-off value may be useful to identify patients at risk for unfavorable outcomes.

Modification of the splice acceptor in CD163 exon 7 of pigs is insufficient to confer resistance to PRRSV

CD163 is the primary receptor for PRRSV, and its SRCR5 domain, encoded by exon 7, is crucial for supporting PRRSV infection. Previous studies have used CRISPR/Cas9 technology to remove exon 7 from the host genome, and the edited pigs were completely resistant to PRRSV infection. In this study, we used CRISPR/Cas9 technology mimicking an adenine base editor (ABE) to edit the splice acceptor site of exon 7, rendering it nonfunctional. This alteration was intended to cause exon 6 to join directly to exon 8 during mRNA processing, resulting in a mature mRNA transcript that lacks exon 7, which encodes the SRCR5 domain. Piglets carrying the exon 7 splice site modification (CD163Ex7-ABE) were successfully generated. However, these pigs remained fully susceptible to infection with a PRRSV-2 isolate. Analysis of CD163 mRNA from the CD163Ex7-ABE pigs revealed that they predominantly expressed a mature CD163 mRNA lacking exon 7. However, due to cryptic splice sites, two additional mRNA isoforms were expressed, including an in-frame variant containing all of exon 7 and an extra 48 base pairs. This likely resulted in the expression of a full-length CD163 with a 16-amino-acid insertion upstream of the SRCR5 domain, which was sufficient to render the animals susceptible to PRRSV. Overall, our results demonstrate that merely modifying the splice acceptor site of CD163 exon 7 is not sufficient to generate PRRSV-resistant pigs.

In vitro ovarian tumor-conditioned CD163+ human macrophages retain phagocytic response to CD47 blockade

INTRODUCTION

CD163-expressing macrophages are abundant in ovarian cancer where they accelerate tumor growth and metastasis. CD47 blockade is a novel immunotherapy aiming to activate macrophage phagocytosis of tumor cells, but it is currently unknown if the tumor-associated macrophages expressing CD163 respond poorly to CD47 blockade.

METHODS

Human monocyte-derived macrophages were exposed to tumor-conditioned medium from A2780 ovarian cancer cells during differentiation. Effects on gene expression, membrane protein levels, release of soluble proteins and macrophage phagocytosis of A2780 cells in response to CD47 blockade were measured and compared to control macrophages.

RESULTS

Tumor cell conditioning induced macrophage expression of CD163 on both the mRNA and protein level. Furthermore, tumor conditioning simultaneously increased protein expression of the phenotype markers CD206 and CD80, and the phagocytosis checkpoint LILRB1. However, tumor conditioning did not reduce phagocytic capacity, as CD47 blockade induced macrophage phagocytosis of A2780 cells to similar degrees in both control and tumor cell-conditioned macrophages.

DISCUSSION

In vitro tumor conditioning did not reduce the phagocytic response to CD47 blockade, suggesting that induction of a macrophage phenotype with increased expression of CD163 does not directly limit the capacity for phagocytosis of tumor cells. In conclusion, these findings suggest that CD163+ macrophages remain responsive to CD47 blockade, highlighting their potential as targets for immunotherapy in ovarian cancer.

Elevated cell-free hemoglobin: A novel early biomarker following traumatic injury

BACKGROUND

Cell-free hemoglobin (CFH) and free heme are potent mediators of endotheliopathy and organ injury in sepsis, but their roles in other hemolytic pathologies are not well-defined. A prime example is trauma where early hemolysis may initiate damage and predict outcome. Here, we investigated the presence of plasma CFH, heme, and their major scavengers after traumatic injury.

METHODS

Adult patients who presented as highest-level activations were prospectively enrolled at a level 1 trauma center between 2021 and 2023. Venous blood was collected upon arrival (pretransfusion) and 6, 12, and 24 hours after admittance for quantification of CFH, haptoglobin, heme, and hemopexin.

RESULTS

We studied 119 mostly male subjects (101:18) with a median age of 48 years (interquartile range [IQR], 31-64 years) and an Injury Severity Score of 22 (IQR, 11-29); the majority had suffered blunt force trauma. The 28-day mortality rate was 11%. Cell-free hemoglobin was high upon emergency department arrival (10.9 μM; IQR, 6.8-17.6) and then declined but remained elevated compared with normative levels during the monitoring period (>5 vs. ~0.2 μM). The initial drop in CFH was attributed to haptoglobin binding and clearance. Notably, there was a subgroup of patients with two- to threefold higher levels of CFH on emergency department arrival (median, 25 μM). Patients with these highest CFH levels had longer hospital stays and more frequent complications.

CONCLUSION

Cell-free hemoglobin is elevated in trauma patients very early after injury and may impact outcome. While further work is needed, early correction of hemolysis could provide benefit.

LEVEL OF EVIDENCE

Prognostic/Epidemiological Study; Level III.

Nucleated Red Blood Cells Secrete Haptoglobin to Induce Immunosuppressive Function in Monocytes

Nucleated red blood cells (NRBCs) are precursors of red blood cells (RBCs), but also possess variety of immunomodulatory effects. However, among the three types of NRBCs, the immunological effects of human CD45- NRBCs remain largely unknown. We have previously shown that cord blood-derived CD45- NRBCs and adult peripheral blood-derived monocytes cocultured in a lipopolysaccharide (LPS)-stimulated indirect coculture system that avoided cell-to-cell contact, increase IL-10 and decrease TNF-α secretion, suggesting an immunosuppressive function of CD45- NRBCs via an unknown soluble factor. The peripheral blood of fetuses and neonates has abundant NRBCs and is physiologically polycythemic, which may lead to the peripheral accumulation of toxic plasma-free hemoglobin. Plasma-free hemoglobin binds to haptoglobin, forming a haptoglobin-hemoglobin complex, which is processed within monocytes via the CD163- heme oxygenase 1 (HO-1) axis and secretes IL-10. Therefore, we hypothesized that NRBCs secrete haptoglobin and induce the immunosuppressive function of monocytes by activating the CD163-HO-1 axis. We found that immunosuppressive response decreased when the coculture medium was supplemented with an anti-CD163 blocking antibody or the HO-1 inhibitor zinc protoporphyrin IX (ZnPP-IX). Haptoglobin levels in the culture medium containing NRBCs were high and expressed the haptoglobin gene. Thus, CD45- NRBCs secreted haptoglobin and activated the immunosuppressive function of monocytes.

Emerging concepts in the molecular cell biology and functions of mammalian erythrocytes

Erythrocytes, or red blood cells, are essential components of vertebrate blood, comprising approximately 45% of human blood volume. Their distinctive features, including small size, biconcave shape, extended lifespan (∼115 days), and lack of a nucleus or other membrane-bound organelles, make them unique among mammalian cell types. Traditionally regarded as passive carriers of oxygen and carbon dioxide, erythrocytes were long thought to function merely as hemoglobin-filled sacs, incapable of gene expression or roles beyond gas transport. However, advancements in molecular biology have revealed a more complex picture. Recent studies have identified various RNA types within erythrocytes, demonstrated globin mRNA translation, and uncovered miRNA-mediated defenses against Plasmodium infection. Beyond gas exchange, erythrocytes play critical roles in regulating regional blood flow via nitric oxide, contribute to innate immunity through toll-like receptors, transport amino acids between tissues, and maintain water homeostasis. Furthermore, emerging technologies have repurposed erythrocytes as drug-delivery vehicles, opening new avenues for therapeutic applications. This review highlights these recent discoveries and explores the expanding functional landscape of erythrocytes, shedding light on their multifaceted roles in physiology and medicine.

Scavenger endothelial cells alleviate tissue damage by engulfing toxic molecules derived from hemolysis

Hemolysis induces tissue damage by releasing cellular contents into the plasma. It is widely accepted that hemolysis-derived toxic molecules are cleared by macrophages or metabolized in hepatocytes. In zebrafish, we found that scavenger endothelial cells (SECs), a specialized endothelium with remarkable endocytosis capability, engulf both macromolecular hemoglobin (Hb) and small molecular unconjugated bilirubin (UCB), two primary toxic byproducts of hemolysis. These engulfment processes are mediated by the scavenger receptor Stab2. To demonstrate the protective function of SECs during hemolysis, we employed a zebrafish model of erythropoietic porphyria, characterized by excessive protoporphyrin IX (PPIX) accumulation due to ferrochelatase mutation, leading to light-sensitive hemolysis and larva death. We found that SECs facilitate the clearance of excess PPIX via Stab2, thereby mitigating PPIX-induced larval mortality. In addition, mouse SECs possess a conserved capability of scavenging Hb/UCB/PPIX. In conclusion, our study identifies SECs as a detoxification system during physiological and pathological hemolysis, shedding light on their protective role against hemolysis-induced damage.

Fucosylated haptoglobin promotes inflammation via Mincle in sepsis: an observational study

Haptoglobin (Hp) scavenges cell-free hemoglobin and correlates with the prognosis of human sepsis, a life-threatening systemic inflammatory condition. Despite extensive research on Hp glycosylation as a glyco-biomarker for cancers, understanding glycosylated modifications of Hp in sepsis patients (SPs) remains limited. Our study reveals elevated levels of terminal fucosylation at Asn207 and Asn211 of Hp in SP plasma, along with heightened inflammatory responses, compared to healthy controls (trial registration NCT05911711). Fucosylated (Fu)-Hp purified from SPs upregulates inflammatory cytokines and chemokines, along with NLRP3 inflammasome activation. Single-cell RNA sequencing identifies a distinct macrophage-like cell population with increased expressions of inflammatory mediators and FUT4 in response to Fu-Hp. Additionally, Mincle, a C-type lectin receptor, interacts with Fu-Hp to amplify the inflammatory responses and signaling. Moreover, the Hp fucosylation (AAL) level significantly correlates with the levels of inflammatory cytokines in sepsis patients, suggesting that Fu-Hp is clinically relevant. Finally, Fu-Hp treatment significantly enhances the levels of inflammatory cytokines in the plasma and various tissues of mice. Together, our findings reveal a role of Fu-Hp, derived from sepsis patients, in driving inflammation, and suggest that targeting Fu-Hp could serve as a promising intervention for combating sepsis. Trial registration NCT05911711.

Intracellular iron accumulation throughout the progression of sepsis influences the phenotype and function of activated macrophages in renal tissue damage

Sepsis, the most common cause of acute kidney injury, remains a major socioeconomic burden. A dysregulated immune response leads to progressive organ dysfunction. Although numerous inflammatory pathways were described, most are still vague and need to be studied in terms of the mechanisms to improve the therapeutic intervention. We tackled the relationship between intracellular iron overload and macrophage polarization within 6, 24, and 72 h of sepsis induction. In our study, sepsis-induced kidney injury was caused by using the cecal ligation and puncture (CLP) model. Our results indicated severe renal tissue damage with a progressive increase in serum BUN and creatinine with architectural tissue damage and positive PAS staining. There was increased expression of CD8+ CD68+ M1 macrophage markers with upregulation of iNOS and co-expression of CD163+. Alternatively, Arg1+ Fizz1+ M2 macrophage markers were downregulated with increased iNOS/Arg1 ratio. TFR1, cubilin, and DMT1, as iron transport systems, were increased compared to sham but were significant after 72 h, while ZIP8 showed no significant change. There was a correlation between iron overload and M1 macrophage polarization with CD163+ phenotype, together with fibrotic changes. The intracellular iron overload with downregulation of ferritin was strongly related to macrophage polarization that was exaggerated at 72 h. Finally, early introduced therapy to target free iron during sepsis is a proposed novel solution for protecting the renal tissue from acute injury due to macrophage activation that may end up with chronic kidney injury, if not mortality.

Revealing the impact of tadalafil-loaded proniosomal gel against dexamethasone-delayed wound healing via modulating oxido-inflammatory response and TGF-β/Macrophage activation pathway in rabbit model

A serious challenge of the chronic administration of dexamethasone (DEX) is a delay in wound healing. Thus, this study aimed to investigate the potential of Tadalafil (TAD)-loaded proniosomal gel to accelerate the healing process of skin wounds in DEX-challenged rabbits. Skin wounds were induced in 48 rabbits of 4 groups (n = 12 per group) and skin wounds were treated by sterile saline (control), TAD-loaded proniosomal gel topically on skin wound, DEX-injected rabbits, and DEX+TAD-loaded proniosomal gel for 4 weeks. The optical photography, transmission electron microscopy, in vitro release profile, and stability studies revealed the successful preparation of the selected formula with good stability. DEX administration was associated with uncontrolled oxido-inflammatory reactions, suppression in immune response in skin wounds, and consequently failure in the healing process. TAD-loaded proniosomal gel-treated rabbits manifested a marked enhancement in the rate of wound closure than control and DEX groups (p < 0.05). The TAD-loaded proniosomal gel successfully antagonized the impacts of DEX by dampening MDA production, and enhancing total antioxidant capacity, coupled with modulation of inflammatory-related genes, inducible nitric oxide synthase, tumor necrosis factor-alpha, interleukin-1β, and matrix metalloproteinase 9, during all healing stages (p < 0.05). This was in combination with significant amplification of immune response-related genes, CD68 and CD163 (p < 0.05). Moreover, the histopathological, Masson's Trichrome-stain, and immune-histochemical studies indicated a successful tissue recovery with the formation of new blood vessels in groups treated with TAD-loaded proniosomal gel, as manifested by well-organized collagen fibers, upregulation of transforming growth factor β1, and vascular endothelial growth factor immune expression in skin tissues (p < 0.05). Overall, the topical application of TAD-loaded proniosomal gel is useful in improving the delayed wound healing linked to DEX therapy via regulating the release of inflammatory/macrophage activation mediators and enhanced antioxidant capacity, angiogenesis, and vascularity.

Molecular basis of hemoglobin binding and heme removal in Corynebacterium diphtheriae

To successfully mount infections, nearly all bacterial pathogens must acquire iron, a key metal cofactor that primarily resides within human hemoglobin. Corynebacterium diphtheriae causes the life-threatening respiratory disease diphtheria and captures hemoglobin for iron scavenging using the surface-displayed receptor HbpA. Here, we show using X-ray crystallography, NMR, and in situ binding measurements that C. diphtheriae selectively captures iron-loaded hemoglobin by partially ensconcing the heme molecules of its α subunits. Quantitative growth and heme release measurements are compatible with C. diphtheriae acquiring heme passively released from hemoglobin's β subunits. We propose a model in which HbpA and heme-binding receptors collectively function on the C. diphtheriae surface to capture hemoglobin and its spontaneously released heme. Acquisition mechanisms that exploit the propensity of hemoglobin's β subunit to release heme likely represent a common strategy used by bacterial pathogens to obtain iron during infections.

Levels of sCD163 in women rheumatoid arthritis: Relationship with cardiovascular risk markers

AIM

The soluble scavenger receptor differentiation antigen 163 (sCD163), a monocyte/macrophage activation marker, is related to cardiovascular mortality in the general population. This study aimed to evaluate their relationship between serum levels of sCD163 with cardiovascular risk indicators in rheumatoid arthritis (RA).

METHODS

A cross-sectional study was performed on 80 women diagnosed with RA. The cardiovascular risks were determined using the lipid profile, metabolic syndrome, and QRISK3 calculator. For the assessment of RA activity, we evaluated the DAS28 with erythrocyte sedimentation rate (DAS28-ESR). The serum levels of sCD163 were determined by the ELISA method. Logistic regression models and receiver operating characteristics (ROC) curve were used to assess the association and predictive value of sCD163 with cardiovascular risk in RA patients.

RESULTS

Levels of sCD163 were significantly higher in RA patients with high sensitivity protein C-reactive to HDL-c ratio (CHR)≥0.121 (p=0.003), total cholesterol/HDL-c ratio>7% (p=0.004), LDL-c/HDL-c ratio>3% (p=0.035), atherogenic index of plasma>0.21 (p=0.004), cardiometabolic index (CMI)≥1.70 (p=0.005), and high DAS28-ESR (p=0.004). In multivariate analysis, levels of sCD163≥1107.3ng/mL were associated with CHR≥0.121 (OR=3.43, p=0.020), CMI≥1.70 (OR=4.25, p=0.005), total cholesterol/HDL-c ratio>7% (OR=6.63, p=0.044), as well as with DAS28-ESR>3.2 (OR=8.10, p=0.008). Moreover, levels of sCD163 predicted CHR≥0.121 (AUC=0.701), cholesterol total/HDL ratio>7% (AUC=0.764), and DAS28-ESR>3.2 (AUC=0.720).

CONCLUSION

Serum levels of sCD163 could be considered a surrogate of cardiovascular risk and clinical activity in RA.

The Cryo-EM structure of human CD163 bound to haptoglobin-hemoglobin reveals molecular mechanisms of hemoglobin scavenging

CD163, a macrophage-specific receptor, plays a critical role in scavenging hemoglobin released during hemolysis, protecting against oxidative effects of heme iron. In the bloodstream, hemoglobin is bound by haptoglobin, leading to its immediate endocytosis by CD163. While haptoglobin's structure and function are well understood, CD163's structure and its interaction with the haptoglobin-hemoglobin complex have remained elusive. Here, we present the cryo-electron microscopy structure of the entire extracellular domain of human CD163 in complex with haptoglobin-hemoglobin. The structure reveals that CD163 assembles into trimers (and to some extent dimers), binding haptoglobin-hemoglobin in their center. Key acidic residues in CD163 interact with lysine residues from both haptoglobin and hemoglobin. Calcium-binding sites located near the haptoglobin-hemoglobin interface in CD163 provide explanation for the calcium dependence of the interaction. Furthermore, we show that the interaction facilitating CD163 oligomerization mimics ligand binding and is also calcium dependent. This structural insight into CD163 advances our understanding of its role in hemoglobin scavenging as well as its broader relevance to structurally related scavenger receptors.

Sialoadhesin-dependent susceptibility and replication of porcine reproductive and respiratory syndrome viruses in CD163-expressing cells

Understanding the molecular interactions between porcine reproductive and respiratory syndrome viruses (PRRSVs) and host cells is crucial for developing effective strategies against PRRSV. CD163, predominantly expressed in porcine macrophages and monocytes, is a key receptor for PRRSV infection. CD169, also known as Sialoadhesin, has emerged as a potential receptor facilitating PRRSV internalization. In this study, we investigated PRRSV susceptibility in relation to CD169 expression in CD163-expressing cells. Susceptibility to PRRSV infection was estimated by immunostaining the N protein using SR30A and quantifying ORF7 using RT-PCR. PRRSV strains adapted to MARC-145 did not infect CD163+/CD169-cells but successfully replicated in CD163+/CD169+ cells. Similarly, porcine alveolar macrophage-isolated PRRSV strains effectively infected and propagated in CD163+/CD169+ cells compared to CD163+/CD169-cells (100% vs. 82.9%). We confirmed that high CD169 expression in CD163-expressing cells increases susceptibility to PRRSVs compared to low or no CD169 expression. In conclusion, CD169 expression level influences viral entry efficiency into CD163-expressing cells, providing valuable insights for isolating wild PRRSVs and producing high-titer PRRS vaccine candidates.

Imaging of tumor-associated macrophage dynamics during immunotherapy using a CD163-specific nanobody-based immunotracer

Immunotherapies have emerged as an effective treatment option for immune-related diseases, such as cancer and inflammatory diseases. However, variations in patient responsiveness limit the broad applicability and success of these immunotherapies. Noninvasive whole-body imaging of the immune status of individual patients during immunotherapy could enable the prediction and monitoring of the patient's response, resulting in more personalized treatments. In this study, we developed a nanobody-based immunotracer targeting CD163, a receptor specifically expressed on macrophages. This anti-CD163 immunotracer bound to human and mouse CD163 with high affinity and specificity without competing for ligand binding. Furthermore, the tracer showed no unwanted immune cell activation and was nonimmunogenic. Upon radiolabeling of the anti-CD163 immunotracer, specific imaging of CD163+ macrophages using micro-single-photon emission computerized tomography/computed tomography or micro-positron emission tomography/CT was performed. The anti-CD163 immunotracer was able to stratify immunotherapy responders from nonresponders (NR) by visualizing differences in the intratumoral CD163+ TAM distribution in Lewis lung carcinoma-ovalbumin tumor-bearing mice receiving an anti-programmed cell death protein-1 (PD-1)/CSF1R combination treatment. Immunotherapy-responding mice showed a more homogeneous distribution of the PET signal in the middle of the tumor, while CD163+ TAMs were located at the tumor periphery in NR. As such, visualization of CD163+ TAM distribution in the tumor microenvironment could allow a prediction or follow-up of therapy response. Altogether, this study describes an immunotracer, specific for CD163+ macrophages, that allows same-day imaging and follow-up of these immune cells in the tumor microenvironment, providing a good basis for the prediction and follow-up of immunotherapy responses in cancer patients.

The Roles of Oxidative Stress and Red Blood Cells in the Pathology of the Varicose Vein

This review discusses sources of reactive oxygen species, enzymatic antioxidant systems, and low molecular weight antioxidants. We present the pathology of varicose veins (VVs), including factors such as hypoxia, inflammation, dysfunctional endothelial cells, risk factors in varicose veins, the role of RBCs in venous thrombus formation, the influence of reactive oxygen species (ROS) and RBCs on VV pathology, and the role of hemoglobin in the damage of particles and macromolecules in VVs. This review discusses the production of ROS, enzymatic and nonenzymatic antioxidants, the pathogenesis of varicose veins as a pathology based on hypoxia, inflammation, and oxidative stress, as well as the participation of red blood cells in the pathology of varicose veins.

Deficiency of the Hemoglobin-Haptoglobin Receptor, CD163, Worsens Insulin Sensitivity in Obese Male Mice

Excessive iron accumulation in metabolic organs such as the adipose tissue, liver, and skeletal muscle is associated with increased diabetes risk. Tissue-resident macrophages serve multiple roles, including managing inflammatory tone and regulating parenchymal iron homeostasis, thus protecting against metabolic dysfunction upon iron overload. The scavenger receptor CD163 is uniquely present on tissue-resident macrophages and plays a significant role in iron homeostasis by clearing extracellular hemoglobin-haptoglobin complexes, thereby limiting oxidative damage caused by free hemoglobin in metabolic tissues. We show that the absence of CD163 exacerbates glucose intolerance and insulin resistance in male mice with obesity. Additionally, loss of CD163 reduced the expression of iron regulatory genes (Tfr1, Cisd1, Slc40a1) in adipose tissue macrophages and anti-inflammatory (M2-like) bone marrow-derived macrophages (BMDMs). Furthermore, CD163 deficiency mediated a proinflammatory shift and limited hemoglobin scavenging specifically in M2-like BMDMs. To this end, iron buffering was diminished in inguinal white adipose tissue (iWAT) macrophages in vivo, which culminated in iron spillover into adipocytes and CD45+ CD11B- nonmyeloid immune cells in iWAT. These findings show that CD163 on tissue-resident macrophages is critical for their anti-inflammatory and hemoglobin scavenging roles, and its absence results in impaired systemic insulin action in an obese setting.

ARTICLE HIGHLIGHTS

Macrophage activation syndrome in Sepsis: from pathogenesis to clinical management

BACKGROUND

Sepsis represents a significant global health and hygiene challenge. Excessive activation of macrophages in sepsis can result in certain patients displaying characteristics akin to those observed in Macrophage Activation Syndrome (MAS). MAS represents a grave immune system disorder characterized by persistent and severe inflammation within the body. In the context of sepsis, MAS presents atypically, leading some researchers to refer to it as Macrophage Activation-Like Syndrome (MALS). However, there are currently no effective treatment measures for this situation. The purpose of this article is to explore potential treatment methods for sepsis-associated MALS.

OBJECTIVE

The objective of this review is to synthesize the specific pathophysiological mechanisms and treatment strategies of MAS to investigate potential therapeutic approaches for sepsis-associated MALS.

METHOD

We searched major databases (including PubMed, Web of Science, and Google Scholar etc.) for literature encompassing macrophage activation syndrome and sepsis up to Mar 2024 and combined with studies found in the reference lists of the included studies.

CONCLUSION

We have synthesized the underlying pathophysiological mechanism of MALS in sepsis, and then summarized the diagnostic criteria and the effects of various treatment modalities utilized in patients with MAS or MALS. In both scenarios, heterogeneous treatment responses resulting from identical treatment approaches were observed. The determination of whether the patient is genuinely experiencing MALS significantly impacts the ultimate outcomes of therapeutic efficacy. In order to tackle this concern, additional clinical trials and research endeavors are imperative.

Inflammation in Abdominal Aortic Aneurysm: Cause or Comorbidity?

Aortic aneurysm is a potentially deadly disease. It is chronic degeneration of the aortic wall that involves an inflammatory response and the immune system, aberrant remodelling of the extracellular matrix, and maladaptive transformation of the aortic cells. This review article focuses on the role of the inflammatory cells in abdominal aortic aneurysm. Studies in human aneurysmal specimens and animal models have identified various inflammatory cell types that could contribute to formation or expansion of aneurysms. These include the commonly studied leukocytes (neutrophils and macrophages) as well as the less commonly explored natural killer cells, dendritic cells, T cells, and B cells. Despite the well-demonstrated contribution of inflammatory cells and the related signalling pathways to development and expansion of aneurysms, anti-inflammatory therapy approaches have demonstrated limitations and may require additional considerations such as a combinational approach in targeting multiple pathways for significant beneficial outcomes.

Role of CD163 in PRRSV infection

Porcine reproductive and respiratory syndrome virus (PRRSV) is a highly infectious agent that poses a significant economic threat to the global swine industry. Efficient viral entry relies on interactions with cellular receptors, with CD163-a cysteine-rich scavenger receptor found on porcine alveolar macrophages (PAMs)-playing a critical role. Extensive evidence supports CD163's essential function in PRRSV infection. This review synthesizes current knowledge about CD163's role, examining its structure-function relationship and identifying specific regions crucial for viral entry. We evaluate the established role of CD163 in PRRSV pathogenesis and highlight areas requiring further investigation, along with the potential for targeted therapeutic interventions. Understanding the molecular determinants of CD163's function is vital for developing effective strategies to control PRRSV infection and mitigate its economic impact on swine production. Further research into the PRRSV-CD163 interactions will be crucial for creating novel antiviral strategies.

Effects of phytosterol ester supplementation on egg weight, biochemical indices, liver immunity and gut microbiota of laying hens during peak laying period

This experiment was aimed to investigate the effects of Phytosterol Ester (PSE) supplementation on egg weight, biochemical indices, liver immunity and gut microbiota of Hy-Line Brown laying hens during peak laying period. A total of 256 healthy Hy-Line Brown laying hens were randomly allocated into 4 groups. Laying hens in the control group were fed a basal diet (CON), while those in the experimental groups received a basal diet containing 10 mg/kg (PSE10), 20 mg/kg (PSE20), or 40 mg/kg (PSE40) mg/kg PSE, respectively. We found that PSE supplementation significantly increased the egg weight in PSE20 and PSE40 groups (P < 0.05) and the serum magnesium (Mg) content in PSE10 and PSE20 groups (P < 0.05), but significantly decreased the serum calcium (Ca) content in PSE40 group (P < 0.05). Moreover, PSE supplementation significantly increased the total protein (TP) content of ovary in all experimental groups (P < 0.01) and decreased the total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) contents of the ovary in PSE20 and PSE40 groups (P < 0.001). In serum, PSE supplementation significantly increased TP content in all experimental groups (P < 0.01) and albumin (ALB) content in PSE20 group (P < 0.05). Alkaline phosphatase (AKP) in PSE20 group, TC content in all experimental groups and LDL-C content in PSE20 and PSE40 groups were significantly decreased (P < 0.05). In egg yolk, PSE supplementation significantly increased TP content in PSE20 and PSE40 groups (P < 0.01) and decreased TC content in PSE20 group (P < 0.01). In liver immunofluorescence, PSE supplementation altered the content of CD163, especially in PSE20 group. Dietary PSE significantly decreased the relative abundance of Bacteroides and Desulfovibrio, while increased the relative abundance of Faecalibacterium, g_unclassified_f_Lachnospiraceae, g_norank_f_Ruminococcaceae, g__unclassified_f__Oscillospiraceae and other bacteria. In conclusion, PSE supplementation increased the average egg weight and total protein, lowered egg yolk, serum and ovary cholesterol of Hy-Line Brown laying hens. At the same time, it can also promote serum magnesium levels, enhanced liver immunity, and improved gut microflora.

A novel process for transcellular hemoglobin transport from macrophages to cancer cells

Hemoglobin (Hb) performs its physiological function within the erythrocyte. Extracellular Hb has prooxidative and proinflammatory properties and is therefore sequestered by haptoglobin and bound by the CD163 receptor on macrophages. In the present study, we demonstrate a novel process of Hb uptake by macrophages independent of haptoglobin and CD163. Unexpectedly, macrophages do not degrade the entire Hb, but instead transfer it to neighboring cells. We have shown that the phenomenon of Hb transfer from macrophages to other cells is mainly mediated by extracellular vesicles. In contrast to the canonical Hb degradation pathway by macrophages, Hb transfer has not been reported before. In addition, we have used the process of Hb transfer in anticancer therapy, where macrophages are loaded with a Hb-anticancer drug conjugate and act as cellular drug carriers. Both mouse and human macrophages loaded with Hb-monomethyl auristatin E (MMAE) effectively killed cancer cells when co-cultured in vitro.

Hydrosulphide-methaemoglobin-albumin cluster: a hydrogen sulphide donor

Methaemoglobin (metHb) possesses inherent characteristics that facilitate reversible binding to hydrogen sulphide. Exogenous hydrogen sulphide supplementation imparts beneficial bioactive effects, including antioxidant and anti-inflammatory; hence, we hypothesized that the metHb-hydrogen sulphide complex could act as a hydrogen sulphide donor for medication. In this study, we prepared a hydrosulphide-metHb-albumin (H2S-metHb-albumin) cluster and examined its applicability as a hydrogen sulphide donor in the mice model of hepatic ischemia-reperfusion injury. Structural analysis revealed that the H2S-metHb-albumin cluster exhibited a nanostructure wherein one metHb was wrapped by an average of three albumins, and hydrogen sulphide was bound to the haem. Additionally, the H2S-metHb-albumin cluster exhibited low-pH responsiveness, leading to sustained release of hydrogen sulphide. Owing to these structural and pharmaceutical characteristics, the severity of hepatic ischemia-reperfusion injury was alleviated via antioxidant and anti-inflammatory effects of the H2S-metHb-albumin cluster treatment. The protective effects were more potent in the H2S-metHb-albumin cluster compared to that in a conventional hydrogen sulphide donor (sodium hydrogen sulphide). No abnormal signs of toxic and biological responses were observed after the H2S-metHb-albumin cluster administration, confirming high biological compatibility. These results successfully establish the proof of concept that the H2S-metHb-albumin cluster is a promising hydrogen sulphide donor. To the best of our knowledge, this is the first report demonstrating the remarkable potential of metHb as a biomaterial for hydrogen sulphide donors.

Transcriptomics of Subcutaneous Tissue of Lipedema Identified Differentially Expressed Genes Involved in Adipogenesis, Inflammation, and Pain

Background

Lipedema is a disease typically affecting women with a symmetrical, painful fat distribution disorder, which is hypothesized to be caused by impaired adipogenesis, inflammation, and extracellular matrix remodeling, leading to fibrosis and the development of edema in lipedema subcutaneous adipose tissue. The pathogenesis and molecular processes leading to lipedema have not yet been clarified.

Methods

A whole transcriptome analysis of subcutaneous tissue of lipedema stages I (n = 12), II (n = 9), and III (n = 8) compared with hypertrophied subcutaneous tissue (n = 4) was performed. Further data about hormonal substitution and body morphology were collected. The study is registered at ClinicalTrials.gov (NCT05861583).

Results

We identified several differentially expressed genes involved in mechanisms leading to the development of lipedema. Some genes, such as PRKG2, MEDAG, CSF1R, BICC1, ERBB4, and ACP5, are involved in adipogenesis, regulating the development of mature adipocytes from mesenchymal stem cells. Other genes, such as MAFB, C1Q, C2, CD68, CD209, CD163, CD84, BCAT1, and TREM2, are predicted to be involved in lipid accumulation, hypertrophy, and the inflammation process. Further genes such as SHTN1, SCN7A, and SCL12A2 are predicted to be involved in the regulation and transmission of pain.

Conclusions

In summary, the pathogenesis and development of lipedema might be caused by alterations in adipogenesis, inflammation, and extracellular matrix remodeling, leading to fibrosis and the formation of edema resulting in this painful disease. These processes differ from hypertrophied adipose tissue and may therefore play a main role in the formation of lipedema.

The CD163/TWEAK/Fn14 axis: A potential therapeutic target for alleviating inflammatory bone loss

Objective

Osteoclast (OC) over-activation is an important cause of bone loss that is strongly correlated with inflammation. Although the CD163/TWEAK/Fn14 axis has been implicated in several inflammatory pathologies, its contributions to inflammatory bone loss remain poorly understood. This study aimed to evaluate the interaction of the CD163/TWEAK/Fn14 axis with OC in inflammatory bone loss.

Methods

To assess the role of CD163 in bone homeostasis, we characterized the bone phenotypes of CD163-deficient mice and their wild-type littermates. CD163 and TWEAK levels were evaluated in the bone marrow of mice with LPS-induced bone loss and individuals with rheumatoid arthritis (RA). Bone mass changes were assessed using uCT and histology following supplementation with recombinant mouse CD163 protein (rCD163) or blockade of TWEAK/Fn14 signaling in CD163-deficient mice and mice with LPS-induced bone loss. The impact of CD163/TWEAK on OC differentiation and bone resorption capacity was analyzed in vitro.

Results

CD163 deficiency caused decreased bone mass and increased OC abundance. Lower CD163 expression and higher TWEAK expression were observed in the bone marrow of mice with LPS-induced bone loss and individuals with RA. TWEAK, mainly derived from CD68+ macrophages, was responsible for bone loss, and supplementing rCD163 or blocking TWEAK/Fn14 signaling contributed to rescue bone loss. TWEAK/Fn14 synergistically promoted RANKL-dependent OC differentiation and bone resorption capability through downstream mitogen-activated protein kinases (MAPK) signaling, while the pro-osteoclastic effect of TWEAK was suppressed by CD163.

Conclusion

Our findings suggest that the CD163/TWEAK/Fn14 axis is a potential therapeutic target for inflammatory bone loss by regulating osteoclastogenesis.

CD163+ Tumor-Associated Macrophage Recruitment Predicts Papillary Thyroid Cancer Recurrence

INTRODUCTION

Skewed immune response plays a pivotal role in tumor progression. Systemic inflammatory responses represented by combined peripheral leukocyte fractions are prognostic predictors of multiple cancers, including thyroid cancer. We previously reported the prognostic significance of lymphocyte-to-monocyte ratio (LMR) in curatively resected papillary thyroid cancer (PTC). Therefore, this study aimed to analyze immune cell profiles in the tumor microenvironment and their association with LMR in curatively resected PTC.

MATERIALS AND METHODS

The immune cell profiles of primary tumors in 162 patients with curatively resected PTC were analyzed clinicopathologically. Immunohistochemistry of tumor-associated macrophages (TAMs), myeloid-derived suppressor cells, and lymphocytes was performed using CD163, CD33, and CD3 antibodies, respectively. Prognostic analysis and correlation assays were performed using the immunocyte profiles. The gene expression of tumor-derived chemokines was assessed using a The Cancer Genome Atlas database.

RESULTS

Patients with a higher density of CD163+ TAMs exhibited a significantly worse prognosis than their counterparts (10-y recurrence-free survival: 80.9% versus 91.2%, P = 0.011). Multivariate prognostic analyses revealed that high CD163+ cell density (P = 0.011), low preoperative LMR (P = 0.003), pN1b (P = 0.005), and high thyroglobulin level (P = 0.038) were independent predictors of recurrence. High CD163+ cell density had a prognostic impact on stage II and III PTC. Interestingly, high CD163+ cell density correlated with low LMR and high monocyte fraction in peripheral blood. Indeed, the expression of TAM-inducible, tumor-derived chemokines is increased in the The Cancer Genome Atlas database.

CONCLUSIONS

A high density of infiltrated CD163+ TAMs predicts recurrence in correlation with low LMR and circulating monocyte accumulation. Thus, TAMs should be considered when assessing advanced PTC.

Interleukin-35 alleviates neuropathic pain and induces an anti-inflammatory shift in spinal microglia in nerve-injured male mice

Immune cells are critical in promoting neuroinflammation and neuropathic pain and in facilitating pain resolution, depending on their inflammatory and immunoregulatory cytokine response. Interleukin (IL)-35, secreted by regulatory immune cells, is a member of the IL-12 family with a potent immunosuppressive function. In this study, we investigated the effects of IL-35 on pain behaviors, spinal microglia phenotype following peripheral nerve injury, and in vitro microglial cultures in male and female mice. Intrathecal recombinant IL-35 treatment alleviated mechanical pain hypersensitivity prominently in male mice, with only a modest effect in female mice after sciatic nerve chronic constriction injury (CCI). IL-35 treatment resulted in sex-specific microglial changes following CCI, reducing inflammatory microglial markers and upregulating anti-inflammatory markers in male mice. Spatial transcriptomic analysis revealed that IL-35 suppressed microglial complement activation in the superficial dorsal horn in male mice after CCI. Moreover, in vitro studies showed that IL-35 treatment of cultured inflammatory microglia mitigated their hypertrophied morphology, increased their cell motility, and decreased their phagocytic activity, indicating a phenotypic shift towards homeostatic microglia. Further, IL-35 altered microglial cytokines/chemokines in vitro, suppressing the release of IL-9 and monocyte-chemoattractant protein-1 and increasing IL-10 in the supernatant of male microglial cultures. Our findings indicate that treatment with IL-35 modulates spinal microglia and alleviates neuropathic pain in male mice, suggesting IL-35 as a potential sex-specific targeted immunomodulatory treatment for neuropathic pain.

Method for quantifying free hemoglobin, distinct from the hemoglobin-haptoglobin complex, in human serum

The measurement of free hemoglobin (free Hb) in blood is crucial for assessing the risk of organ damage in patients with hemolytic diseases. However, the colorimetric method, commonly used in clinical practice, does not distinguish between free Hb and the hemoglobin-haptoglobin complex (Hb-Hp) in the blood, instead reflecting the total Hb level. Although size-exclusion high-performance liquid chromatography (SEC-HPLC) can specifically measure free Hb, its clinical use is limited by long assay times. Here, we developed a novel assay method for the rapid quantification of free Hb in serum, distinguishing it from Hb-Hp, using a latex agglutination immunoturbidimetric assay (LATIA). This method could be used to measure free Hb in sera in the range of 1-100 μg/mL in approximately 15 min using an automatic biochemistry analyzer. Using Hb-spiked serum samples from healthy adults, there was a high correlation with Hb levels determined using the newly developed method and SEC-HPLC, indicating a high specificity for free Hb. This novel assay can be used to monitor levels of free Hb in patients with various hemolytic diseases and to design therapeutic strategies based on measured values. However, further studies are required to assess its clinical performance.

snRNA-seq of adipose tissues reveals the potential cellular and molecular mechanisms of cold and disease resistance in Mongolian cattle

BACKGROUND

Mongolian cattle are local breeds in northern China with excellent adaptability to harsh environmental conditions. Adipose tissues play essential roles in tolerance to cold and disease, but the associated cellular and molecular mechanisms are unclear.

METHODS

Single-nucleus RNA sequencing (snRNA-seq) was performed on the adipose tissues from the subcutaneous (SAT), greater omentum (OAT) and perirenal (PAT) of 3 healthy cattle. The adipogenic trajectory was analyzed, and the functional roles of gene of interest were verified in vitro.

RESULTS

There were different cell subpopulations in adipose tissues. The lipid-deposition adipocytes identified by the PTGER3 marker exhibited outstanding characteristics in SAT. In PAT and OAT, aldosterone was expressed to provide clues for the differential brown adipocytes. Among the DEGs by comparing OAT with SAT and PAT with OAT, C3 was significantly expressed in most of the cell populations in SAT. G0S2, LIPE, LPIN1, PTGER3 and RGCC took part in the adipogenic trajectory from preadipocyte commitment to mature adipocytes. S100A4 expression affected Ca2+ signaling and the expression of UCP1 ~ 3, FABP4 and PTGER3.

CONCLUSION

The cell heterogeneity and genes expressed in adipose tissues of Mongolian cattle not only determine the endocrine and energy storage, but contribute to adapt to cold and disease resistance.

The Role of Soluble CD163 (sCD163) in Human Physiology and Pathophysiology

Soluble CD163 (sCD163) is a circulating inflammatory mediator, indicative of acute and chronic, systemic and non-systemic inflammatory conditions. It is the cleavage outcome, consisting of almost the entire extracellular domain, of the CD163, a receptor expressed in monocytic lineages. Its expression is proportional to the abundance of CD163+ macrophages. Various mechanisms trigger the shedding of the CD163 receptor or the accumulation of CD163-expressing macrophages, inducing the sCD163 concentration in the circulation and bodily fluids. The activities of sCD163 range from hemoglobin (Hb) scavenging, macrophage marker, decoy receptor for cytokines, participation in immune defense mechanisms, and paracrine effects in various tissues, including the endothelium. It is an established marker of macrophage activation and thus participates in many diseases, including chronic inflammatory conditions, such as atherosclerosis, asthma, and rheumatoid arthritis; acute inflammatory conditions, such as sepsis, hepatitis, and malaria; insulin resistance; diabetes; and tumors. The sCD163 levels have been correlated with the severity, stage of the disease, and clinical outcome for many of these conditions. This review article summarizes the expression and role of sCD163 and its precursor protein, CD163, outlines the sCD163 generation mechanisms, the biological activities, and the known underlying molecular mechanisms, with an emphasis on its impact on the endothelium and its contribution in the pathophysiology of human diseases.

Granulomas in Common Variable Immunodeficiency Display Different Histopathological Features Compared to Other Granulomatous Diseases

Granulomatous disease affects up to 20% of patients with Common Variable Immunodeficiency (CVID). Granulomas are comprised of highly activated immune cells, and emerge in response to antigenic triggers. In CVID granulomas however, the underlying pathophysiology is unclear and the specific trigger remains unknown. Granuloma formation in CVID is often compared to sarcoidosis, although clinical context and prognosis differ, suggesting a different pathogenesis. The aim of this study was to investigate if the cellular organization and proteomics of granulomas in CVID is different from other granulomatous diseases. Therefore, tissue slides from formaldehyde fixed paraffin embedded biopsies obtained from patients with CVID, sarcoidosis, tuberculosis and foreign-material induced pseudo-sarcoidosis were stained with hematoxylin and eosin and assessed for histopathological characteristics. Targeted spatial protein analysis was performed, and immune fluorescent multiplex assays were used to analyze the cellular organization. Histological analysis revealed that CVID granulomas were smaller, less circumscribed, with fewer multinucleated giant cells and minimal fibrosis compared to the other granulomatous diseases. Spatial protein analysis showed that granulomas in all diseases expressed CD68, CD11c, CD44, CD127, and PD-L1. However in CVID, reduced expression of the fibrosis-related protein fibronectin, but enrichment of CD163, CD3 and FAPα inside CVID granulomas was observed. Immunofluorescence analysis conformed a different cellular organization in CVID granulomas with increased influx of neutrophils, macrophages, T and B lymphocytes. In conclusion, granulomas in CVID display a different histological and cellular organization with increased influx of myeloid and lymphoid cells, compared to sarcoidosis, tuberculosis and pseudo-sarcoidosis, indicating a distinct pathogenesis underlying granuloma formation.

Haptoglobin buffers lipopolysaccharides to delay activation of NFκB

It has remained yet unclear which soluble factors regulate the anti-inflammatory macrophage phenotype observed in both homeostasis and tumourigenesis. We show here that haptoglobin, a major serum protein with elusive immunoregulatory properties, binds and buffers bacterial lipopolysaccharides to attenuate activation of NFκB in macrophages. Haptoglobin binds different lipopolysaccharides with low micromolar affinities. Given its abundance, haptoglobin constitutes a buffer for serum-borne lipopolysaccharides, shielding them to safeguard against aberrant inflammatory reactions by reducing the amount of free lipopolysaccharides available for binding to TLR4. Concordantly, NFκB activation by haptoglobin-associated lipopolysaccharides was markedly delayed relative to stimulation with pure lipopolysaccharide. Our findings warrant evaluation of therapeutic benefits of haptoglobin for inflammatory conditions and re-evaluation of purification strategies. Finally, they allow to elucidate mechanisms of enhanced immunosuppression by oncofetal haptoglobin.

The intervention of macrophages in progressive fibrosis characterizing systemic sclerosis: A systematic review

BACKGROUND AND AIM

Systemic sclerosis (SSc) is an immune mediated connective tissue disease characterized by microvascular dysfunction, aberrant immune response, and progressive fibrosis. Although the immuno-pathophysiological mechanisms underlying SSc are not fully clarified, they are often associated with a dysfunctional macrophage activation toward an alternative (M2) phenotype induced by cytokines [i.e., IL-4, IL-10, IL-13, and transforming growth factor (TGF-β)] involved in the fibrotic and anti-inflammatory process. A spectrum of macrophage activation state has been identified ranging from M1 to M2 phenotype, gene expression of phenotype markers, and functional aspects. This systematic review aims to analyze the importance of M2 macrophage polatization during the immune mediated process and the identification of specific pathways, cytokines, and chemokines involved in SSc pathogenesis. Moreover, this review provides an overview on the in vitro and in vivo studies aiming to test therapeutic strategies targeting M2 macrophages.

METHODS

A systematic literature review was performed according to the preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA). The search encompassed the online medical databases PubMed and Embase up to the 30th of June 2024. Original research manuscripts (in vitro study, in vivo study), animal model and human cohort, were considered for the review. Exclusion criteria encompassed reviews, case reports, correspondences, and conference abstracts/posters. The eligible manuscripts main findings were critically analyzed, discussed, and summarized in the correspondent tables.

RESULTS

Out of the 77 screened abstracts, 49 papers were deemed eligible. Following a critical analysis, they were categorized according to the primary (29 original articles) and secondary (20 original articles) research objectives of this systematic review. The data from the present systematic review suggest the pivotal role of M2 macrophages differentiation and activation together with the dysregulation of the immune system in the SSc pathogenesis. Strong correlations have been found between M2 macrophage presence and clinical manifestations in both murine and human tissue samples. Interestingly, the presence of M2 cell surface markers on peripheral blood monocytes has been highlighted, suggesting a potential biomarker role for this finding. Therapeutic effects reducing M2 macrophage activities have been observed and/or tested for existing and for new drugs, demonstrating potential efficacy in modulating the pro-fibrotic immune response for treatment of SSc.

CONCLUSIONS

The increased M2 macrophage activation in course of SSc seems to offer new insights on the self-amplifying inflammatory and fibrotic response by the immune system on such disease. Therefore, the revaluation of immunomodulatory and ongoing antifibrotic therapies, as well as novel therapeutical approaches in SSc that contribute to limit the M2 macrophage activation are matter of intense investigations.

Increased Parenchymal Macrophages are associated with decreased Tyrosine Hydroxylase mRNA levels in the Substantia Nigra of people with Schizophrenia and Bipolar Disorder

Increased activation of inflammatory macrophages and altered expression of dopamine markers are found in the midbrains of people with schizophrenia (SZ). The relationship of midbrain macrophages to dopamine neurons has not been explored, nor is it known if changes in midbrain macrophages are also present in bipolar disorder (BD) or major depressive disorder (MDD). Herein, we determined whether there were differences in CD163+ cell density in the Substantia Nigra (SN), and cerebral peduncles (CP) of SZ, BD, and MDD compared to controls (CTRL). We also analyzed whether CD163 protein and dopamine-synthesizing enzyme tyrosine hydroxylase (TH) mRNA levels differed among diagnostic groups and if they correlated with the density of macrophages. Overall, perivascular CD163+ cell density was higher in the gray matter (SN) than in the white matter (CP). Compared to CTRL, we found increased density of parenchymal CD163+ cells in the SN of the three psychiatric groups and increased CD163 protein levels in SZ. CD163 protein was positively correlated with density of perivascular CD163+ cells. TH mRNA was reduced in SZ and BD and negatively correlated with parenchymal CD163+ cell density. We provide the first quantitative and molecular evidence of an increase in the density of parenchymal macrophages in the midbrain of major mental illnesses and show that the presence of these macrophages may negatively impact dopaminergic neurons.

Correlation of Urinary Soluble CD163 Levels With Disease Activity and Treatment Response in IgA Nephropathy

Introduction

The TESTING trial demonstrated that corticosteroids reduce the risk of kidney failure in patients with IgA nephropathy (IgAN) but increase the risk of serious adverse events. Reliable noninvasive biomarkers are needed to identify patients who would benefit most from corticosteroid therapy. Previous studies suggest glomerular macrophage infiltration is associated with response to immunosuppressive therapy in IgAN and urinary soluble CD163 ([u-sCD163], a marker of alternatively activated macrophages [M2]c macrophage) is correlated with clinical remission in vasculitis. This study aims to investigate the association between u-sCD163 and response of steroids therapy in IgAN.

Methods

We measured u-sCD163 in patients from a large IgAN cohort and Chinese participants of the TESTING trial. The correlation of baseline or serial u-sCD163 and their response of corticosteroids therapy or kidney outcomes were investigated.

Results

In cross-sectional analysis, u-sCD163 levels correlated with kidney macrophage infiltration, especially in crescentic areas, and with active lesions. Subgroup analysis of the TESTING cohort showed higher levels u-sCD163 were associated with greater benefits from corticosteroids therapy in proteinuria remission (odds ratio, 35.56 [95% confidence interval, CI: 7.62-292.34] vs. 3.94 [95% CI: 1.39-12.93], P for interaction: 0.036). Corticosteroids therapy significantly reduced u-sCD163 levels at 6 months compared to placebo group (79% [interquartile range: 58%-91%] vs. 37% [-11% to 58%], P <0.001). There was no difference in the suppressive effects on u-sCD163 by either dosage of corticosteroids (full and reduced-dose). The suppression of u-sCD163 was significantly associated with a reduced risk of kidney progression events (adjusted hazard ratio: 0.52, 95% CI: 0.30-0.93, P = 0.027).

Conclusion

u-sCD163 is a reliable noninvasive biomarker associated with active pathological lesions in IgAN and can guide glucocorticoid therapy.

Therapeutics for sickle cell disease intravascular hemolysis

Sickle cell disease (SCD) is a genetic disorder predominantly affecting individuals of African descent, with a significant global health burden. SCD is characterized by intravascular hemolysis, driven by the polymerization of mutated hemoglobin within red blood cells (RBCs), leading to vascular inflammation, organ damage, and heme toxicity. Clinical manifestations include acute pain crises, hemolytic anemia, and multi-organ dysfunction, imposing substantial morbidity and mortality challenges. Current therapeutic strategies mitigate these complications by increasing the concentration of RBCs with normal hemoglobin via transfusion, inducing fetal hemoglobin, restoring nitric oxide signaling, inhibiting platelet-endothelium interaction, and stabilizing hemoglobin in its oxygenated state. While hydroxyurea and gene therapies show promise, each faces distinct challenges. Hydroxyurea's efficacy varies among patients, and gene therapies, though effective, are limited by issues of accessibility and affordability. An emerging frontier in SCD management involves harnessing endogenous clearance mechanisms for hemolysis products. A recent work by Heggland et al. showed that CD-36-like proteins mediate heme absorption in hematophagous ectoparasite, a type of parasite that feeds on the blood of its host. This discovery underscores the need for further investigation into scavenger receptors (e.g., CD36, SR-BI, SR-BII) for their possible role in heme uptake and detoxification in mammalian species. In this review, we discussed current SCD therapeutics and the specific stages of pathophysiology they target. We identified the limitations of existing treatments and explored potential future developments for novel SCD therapies. Novel therapeutic targets, including heme scavenging pathways, hold the potential for improving outcomes and reducing the global burden of SCD.

Transport of Zinc-Phthalocyanine to Cancer Cells Using Myoglobin-Albumin Fusion Protein for Photodynamic Therapy

Photodynamic therapy (PDT) is a noninvasive approach to cancer treatment, wherein cell death is initiated by singlet oxygen (1O2) production via energy transfer from excited photosensitizers to ground-state O2. Effective clinical photosensitizers necessitate water solubility for in vivo administration. Hydrophobic dyes, such as phthalocyanines, cannot be used directly as photosensitizers. Herein, we synthesized a myoglobin-(human serum albumin) fusion protein reconstituted with zinc-phthalocyanine (ZnPc), termed ZnPcMb-HSA. The photophysical properties of ZnPcMb-HSA closely resemble those of ZnPc-substituted Mb. Notably, ZnPc dissociates from ZnPcMb-HSA and selectively accumulates within cancer cells, while the protein components remain extracellular. Treatment of four distinct cell lines with ZnPcMb-HSA, followed by red-light irradiation, effectively induced apoptosis. The half-maximal inhibitory concentrations (IC50) against these cancer cell lines ranged between 0.1-0.5 μM. Reconstituted Mb-HSA emerges as a promising carrier for transporting various water-insoluble porphyrinoid photosensitizer to target cancer cells in PDT applications.

Clinical landscape of macrophage-reprogramming cancer immunotherapies

Tumour-associated macrophages (TAMs) sustain a tumour-supporting and immunosuppressive milieu and therefore aggravate cancer prognosis. To modify TAM behaviour and unlock their anti-tumoural potential, novel TAM-reprogramming immunotherapies are being developed at an accelerating rate. At the same time, scientific discoveries have highlighted more sophisticated TAM phenotypes with complex biological functions and contradictory prognostic associations. To understand the evolving clinical landscape, we reviewed current and past clinically evaluated TAM-reprogramming cancer therapeutics and summarised almost 200 TAM-reprogramming agents investigated in more than 700 clinical trials. Observable overall trends include a high frequency of overlapping strategies against the same therapeutic targets, development of more complex strategies to improve previously ineffective approaches and reliance on combinatory strategies for efficacy. However, strong anti-tumour efficacy is uncommon, which encourages re-directing efforts on identifying biomarkers for eligible patient populations and comparing similar treatments earlier. Future endeavours will benefit from considering the shortcomings of past treatment strategies and accommodating the emerging complexity of TAM biology.

PRRSV infection facilitates the shedding of soluble CD163 to induce inflammatory responses

Porcine reproductive and respiratory syndrome (PRRS), which poses substantial threats to the global pig industry, is primarily characterized by interstitial pneumonia. Cluster of differentiation 163 (CD163) is the essential receptor for PRRSV infection. Metalloproteinase-mediated cleavage of CD163 leads to the shedding of soluble CD163 (sCD163), thereby inhibiting PRRSV proliferation. However, the exact cleavage site in CD163 and the potential role of sCD163 in inflammatory responses during PRRSV infection remain unclear. Herein, we found that PRRSV infection increased sCD163 levels, as demonstrated in primary alveolar macrophages (PAMs), immortalized PAM (IPAM) cell lines, and sera from PRRSV-infected piglets. With LC-MS/MS, Arg-1041/Ser-1042 was identified as the cleavage site in porcine CD163, and an IPAM cell line with precise mutation at the cleavage site was constructed. Using the precisely mutated IPAM cells, we found that exogenous addition of sCD163 protein promoted inflammatory responses, while mutation at the CD163 cleavage site suppressed inflammatory responses. Consistently, inhibition of sCD163 using its neutralizing antibodies reduced PRRSV infection-triggered inflammatory responses. Importantly, sCD163 promoted cell polarization from M2 to M1 phenotype, which in turn facilitated inflammatory responses. Taken together, our findings identify sCD163 as a novel proinflammatory mediator and provide valuable insights into the mechanisms underlying the induction of inflammatory responses by PRRSV infection.

Development and validation of a nomogram to predict severe influenza

BACKGROUND

Influenza is an acute respiratory disease posing significant harm to human health. Early prediction and intervention in patients at risk of developing severe influenza can significantly decrease mortality.

METHOD

A comprehensive analysis of 146 patients with influenza was conducted using the Gene Expression Omnibus (GEO) database. We assessed the relationship between severe influenza and patients' clinical information and molecular characteristics. First, the variables of differentially expressed genes were selected using R software. Least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression analysis were performed to investigate the association between clinical information and molecular characteristics and severe influenza. A nomogram was developed to predict the presence of severe influenza. At the same time, the concordance index (C-index) is adopted area under the receiver operating characteristic (ROC), area under the curve (AUC), decision curve analysis (DCA), and calibration curve to evaluate the predictive ability of the model and its clinical application.

RESULTS

Severe influenza was identified in 47 of 146 patients (32.20%) and was significantly related to age and duration of illness. Multivariate logistic regression demonstrated significant correlations between severe influenza and myloperoxidase (MPO) level, haptoglobin (HP) level, and duration of illness. A nomogram was formulated based on MPO level, HP level, and duration of illness. This model produced a C-index of 0.904 and AUC of 0.904.

CONCLUSIONS

A nomogram based on the expression levels of MPO, HP, and duration of illness is an efficient model for the early identification of patients with severe influenza. These results will be useful in guiding prevention and treatment for severe influenza disease.

cAMP signaling of Bordetella adenylate cyclase toxin blocks M-CSF triggered upregulation of iron acquisition receptors on differentiating CD14+ monocytes

Bordetella pertussis infects the upper airways of humans and disarms host defense by the potent immuno-subversive activities of its pertussis (PT) and adenylate cyclase (CyaA) toxins. CyaA action near-instantly ablates the bactericidal activities of sentinel CR3-expressing myeloid phagocytes by hijacking cellular signaling pathways through the unregulated production of cAMP. Moreover, CyaA-elicited cAMP signaling also inhibits the macrophage colony-stimulating factor (M-CSF)-induced differentiation of incoming inflammatory monocytes into bactericidal macrophages. We show that CyaA/cAMP signaling via protein kinase A (PKA) downregulates the M-CSF-elicited expression of monocyte receptors for transferrin (CD71) and hemoglobin-haptoglobin (CD163), as well as the expression of heme oxygenase-1 (HO-1) involved in iron liberation from internalized heme. The impact of CyaA action on CD71 and CD163 levels in differentiating monocytes is largely alleviated by the histone deacetylase inhibitor trichostatin A (TSA), indicating that CyaA/cAMP signaling triggers epigenetic silencing of genes for micronutrient acquisition receptors. These results suggest a new mechanism by which B. pertussis evades host sentinel phagocytes to achieve proliferation on airway mucosa.IMPORTANCETo establish a productive infection of the nasopharyngeal mucosa and proliferate to sufficiently high numbers that trigger rhinitis and aerosol-mediated transmission, the pertussis agent Bordetella pertussis deploys several immunosuppressive protein toxins that compromise the sentinel functions of mucosa patrolling phagocytes. We show that cAMP signaling elicited by very low concentrations (22 pM) of Bordetella adenylate cyclase toxin downregulates the iron acquisition systems of CD14+ monocytes. The resulting iron deprivation of iron, a key micronutrient, then represents an additional aspect of CyaA toxin action involved in the inhibition of differentiation of monocytes into the enlarged bactericidal macrophage cells. This corroborates the newly discovered paradigm of host defense evasion mechanisms employed by bacterial pathogens, where manipulation of cellular cAMP levels blocks monocyte to macrophage transition and replenishment of exhausted phagocytes, thereby contributing to the formation of a safe niche for pathogen proliferation and dissemination.