The macrophage is a key cell in the pro- and anti-inflammatory response including that of the inflammatory microenvironment of malignant tumors. Much current drug development in chronic inflammatory ...diseases and cancer therefore focuses on the macrophage as a target for immunotherapy. However, this strategy is complicated by the pleiotropic phenotype of the macrophage that is highly responsive to its microenvironment. The plasticity leads to numerous types of macrophages with rather different and, to some extent, opposing functionalities, as evident by the existence of macrophages with either stimulating or down-regulating effect on inflammation and tumor growth. The phenotypes are characterized by different surface markers and the present review describes recent progress in drug-targeting of the surface marker CD163 expressed in a subpopulation of macrophages. CD163 is an abundant endocytic receptor for multiple ligands, quantitatively important being the haptoglobin-hemoglobin complex. The microenvironment of inflammation and tumorigenesis is particular rich in CD163
macrophages. The use of antibodies for directing anti-inflammatory (e.g., glucocorticoids) or tumoricidal (e.g., doxorubicin) drugs to CD163
macrophages in animal models of inflammation and cancer has demonstrated a high efficacy of the conjugate drugs. This macrophage-targeting approach has a low toxicity profile that may highly improve the therapeutic window of many current drugs and drug candidates.
The hemoglobin scavenger receptor CD163 is exclusively expressed in the monocytic lineage and preferentially in tissue resident macrophages of the M2 phenotype and in macrophages in sites of ...inflammation and tumor growth. In the present study we have designed liposomes specifically targeting CD163 by hydrophobic linkage of CD163-binding monoclonal antibodies to polyethylene glycol-coated liposomes (‘stealth liposomes’). Targeting to the endocytic CD163 protein greatly increased the uptake of liposomes in CD163 transfected cells and macrophages as visualized by confocal microscopy and flow cytometry of cells exposed to CD163 targeting liposomes loaded with calcein. Strong cytotoxic effects were seen in CD163-expressing human monocytes by using the chemotherapeutic agent doxorubicin as cargo of the liposomes.
In conclusion, the use of stealth liposomes modified to recognize CD163 is a potential way to target drugs to macrophages that support inflammatory and malignant processes.
Display omitted
Macrophages are important cells in immunity and the main producers of pro-inflammatory cytokines. The main objective was to evaluate if specific delivery of glucocorticoid to the macrophage receptor ...CD163 is superior to systemic glucocorticoid therapy in dampening the cytokine response to lipopolysaccharide infusion in pigs.
Two randomized, placebo-controlled trials.
University hospital laboratory.
Female farm-bred pigs (26-31 kg).
A humanized antibody that binds to pig and human CD163 was produced, characterized, and conjugated with dexamethasone. In the first study (total n = 12), pigs were randomly assigned to four groups: 1) saline; 2) dexamethasone (1.0 mg/kg); 3) dexamethasone (0.02 mg/kg); and 4) anti-CD163-conjugated dexamethasone (0.02 mg/kg). In the second study (total n = 36), two additional groups were included in addition to the four original groups: 5) anti-CD163-conjugated dexamethasone (0.005 mg/kg); 6) unconjugated anti-CD163. Treatments were given 20 hours prior to infusion of lipopolysaccharide (1 µg × kg × h) for 5 hours. Blood samples were analyzed for cytokines, cortisol, and adrenocorticotropic hormone.
In the saline group, lipopolysaccharide increased cytokine and plasma cortisol levels. In both studies, dexamethasone (1 mg/kg) and anti-CD163 dexamethasone (0.02 mg/kg) uniformly attenuated tumor necrosis factor-α peak levels (both p < 0.05) compared with low-dose dexamethasone (0.02 mg/kg). However, dexamethasone 1 mg/kg significantly suppressed plasma cortisol and adrenocorticotropic hormone levels compared with anti-CD163 dexamethasone (0.02 mg/kg; p < 0.05). No significant hemodynamic difference existed between groups. The anti-CD163 dexamethasone drug conjugate exhibited a fast plasma clearance, with a half-life of approximately 5-8 minutes.
Targeted delivery of dexamethasone to macrophages using a humanized CD163 antibody as carrier exhibits anti-inflammatory effects comparable with 50 times higher concentrations of free dexamethasone and does not inhibit endogenous cortisol production. This antibody-drug complex showing similar affinity and specificity for human CD163 is, therefore, a promising drug candidate in this novel type of anti-inflammatory therapy.
The contact system consists of coagulation factor XII (FXII), prekallikrein, and H-kininogen (HK) and plays important roles in many diseases. Plasma kallikrein (PKa) cleaved HK (cHK) is a marker of ...contact activation. Presently, we developed a specific and precise enzyme-linked immunosorbent assay (ELISA) for determination of cHK
and
Cleaved HK specific mouse monoclonal antibodies (mAbs) were generated using a peptide corresponding to the PKa cleavage site on HK as immunogen. ELISA, surface plasmon resonance analysis, and immunoprecipitation established the specificity of the antibody, which subsequently was used in a sandwich ELISA. The analytical imprecision and the concentration of cHK in a reference population and in women receiving oral contraceptives (OC) were determined. cHK was assessed
in plasma exposed to polytetrafluoroethylene, silicone, and glass tubes.
The selected mAb showed excellent specificity towards cHK. The intra-assay and inter-assay CV of the ELISA were 3.6 and 6.0%, respectively. The reference population (60 women, 60 men) displayed a median cHK plasma concentration of 1.38 μg/mL and a reference interval of 0.82 - 2.56 μg/mL. Women receiving OC had significantly higher concentrations,
< 0.001. cHK was significantly elevated in plasma exposed to polytetrafluoroethylene,
= 0.001, and glass,
< 0.0001.
The ELISA showed excellent precision and specificity. cHK assessment
demonstrated ongoing contact activation in healthy individuals, augmented by OC. The cHK antibody and the ELISA could be promising tools in contact activation related diseases and
investigations of the plasma compatibility of blood contacting biomaterials.
AIM: To study the effect of a new anti-CD163-dexamethasone conjugate targeting activated macrophages on the hepatic acute phase response in rats. METHODS: Wistar rats were injected intravenous with ...either the CD163 targeted dexamethasone-conjugate(0.02 mg/kg) or free dexamethasone(0.02 or 1 mg/kg) 24 h prior to lipopolysaccharide(LPS)(2.5 mg/kg intraperitoneal). We measured plasma concentrations of tumour necrosis factor-a(TNF-a) and interleukin 6(IL-6) 2 h post-LPS and liver m RNAs and serum concentrations of the rat acute phase protein a-2-macroglobulin(a-2-M) 24 h after LPS. Also, plasma concentrations of alanine aminotransferase and bilirubin were measured at termination of the study. Spleen weight served as an indicator of systemic steroid effects.RESULTS: The conjugate halved the a-2-M liver m RNA(3.3 ± 0.6 vs 6.8 ± 1.1, P < 0.01) and serum protein(201 ± 48 μg/mL vs 389 ± 67 μg/mL, P = 0.04) after LPS compared to low dose dexamethasone treated animals, while none of the free dexamethasone doses had an effect on liver m RNA or serum levels of a-2-M. Also, the conjugate reduced TNF-a(7208 ± 1977 pg/mL vs 21583 ± 7117 pg/mL, P = 0.03) and IL-6(15685 ± 3779 pg/mL vs 25715 ± 4036 pg/mL, P = 0.03) compared to the low dose dexamethasone. The high dose dexamethasone dose decreased the spleen weight(421 ± 11 mg vs 465 ± 12 mg, P < 0.05) compared to controls, an effect not seen in any other group.CONCLUSION: Low-dose anti-CD163-dexamethasone conjugate effectively decreased the hepatic acute phase response to LPS. This indicates an anti-inflammatory potential of the conjugate in vivo.
In inflammatory diseases, macrophages are a main producer of a range of cytokines regulating the inflammatory state. This also includes inflammation induced by tumor growth, which recruits so-called ...tumor-associated macrophages supporting tumor growth. Macrophages are therefore relevant targets for cytotoxic or phenotype-modulating drugs in the treatment of inflammatory and cancerous diseases. Such targeting of macrophages has been tried using the natural propensity of macrophages to non-specifically phagocytose circulating foreign particulate material. In addition, the specific targeting of macrophage-expressed receptors has been used in order to obtain a selective uptake in macrophages and reduce adverse effects of off-target delivery of drugs. CD163 is a highly expressed macrophage-specific endocytic receptor that has been studied for intracellular delivery of small molecule drugs to macrophages using targeted liposomes or antibody drug conjugates. This review will focus on the biology of CD163 and its potential role as a target for selective macrophage targeting compared with other macrophage targeting approaches.
The hemoglobin scavenger receptor (HbSR/CD163) is an interleukin-6– and glucocorticoid-regulated macrophage/monocyte receptor for uptake of haptoglobin-hemoglobin complexes. Moreover, there are ...strong indications that HbSR serves an anti-inflammatory function. Immunoprecipitation and immunoblotting enabled identification of a soluble plasma form of HbSR (sHbSR) having an electrophoretic mobility equal to that of recombinant HbSR consisting of the extracellular domain (scavenger receptor cysteine-rich 1-9). A sandwich enzyme-linked immunosorbent assay was established and used to measure the sHbSR level in 130 healthy subjects (median, 1.87 mg/L; range, 0.73-4.69 mg/L). To evaluate the sHbSR levels in conditions with increased leukocyte stimulation and proliferation, 140 patients admitted to a hematological department were screened. Several patients, with a broad spectrum of diagnoses, had a level of sHbSR above the range of healthy persons. Patients with myelomonocytic leukemias and pneumonia/sepsis exhibited the highest levels (up to 67.3 mg/L). In conclusion, sHbSR is an abundant plasma protein potentially valuable in monitoring patients with infections and myelomonocytic leukemia.
Macrophages play an important role in the development of nonalcoholic fatty liver disease (NAFLD) and its progression to nonalcoholic steatohepatitis (NASH). In this study, we investigated the ...hepatic expression of the macrophage scavenger receptor CD163 and the plasma level of its shed soluble form (sCD163) in patients with obesity and NASH, non-NASH NAFLD (NAFL), or healthy livers (no NAFLD).
Paired liver biopsies and plasma samples were collected from 61 patients with obesity (body mass index ≥35). Hepatic expression of CD163 was analyzed by immunohistochemistry and data-independent acquisition mass spectrometry, whilst plasma levels of sCD163 were determined by enzyme-linked immunosorbent assay and data-independent acquisition mass spectrometry. NAFLD stage and activity were assessed using the Kleiner fibrosis and NASH Clinical Research Network (NAS-CRN) scoring system.
sCD163 turned out as a promising predictor of NASH with an area under the receiver-operating characteristic curve of 0.78 0.65;0.92 (P = .0008). sCD163 increased with more severe NAFLD both in univariate (odds ratio OR = 3.311.80;6.11, P < .001) and multivariable ordinal logistic regression adjusting for NAFLD risk factors (OR = 2.02 1.03;3.97, P = .042). On the other hand, hepatic expression of CD163 was negatively associated with more severe NAFLD in univariate ordinal logistic regression determined by immunohistochemistry (OR = 0.910.84;0.98, P = .015) and proteomics (OR = 0.130.02;0.80, P = .028). Taking NAFLD risk factors into account, hepatic expression of CD163 was only associated with the fibrosis stage (OR = 0.01 0.0003;0.21, P = .004). Accordingly, hepatic CD163 surface expression and sCD163 were negatively correlated (rho = −0.478, P = .0001).
An increased plasma sCD163 and a concurrent decreased hepatic expression of CD163 are strongly associated with NAFLD in obese patients.
Tumor-associated macrophages (TAMs) play critical roles in tumor progression but are also capable of contributing to antitumor immunity. Recent studies have revealed an unprecedented heterogeneity ...among TAMs in both human cancer and experimental models. Nevertheless, we still understand little about the contribution of different TAM subsets to tumor progression. Here, we demonstrate that CD163-expressing TAMs specifically maintain immune suppression in an experimental model of melanoma that is resistant to anti-PD-1 checkpoint therapy. Specific depletion of the CD163
macrophages results in a massive infiltration of activated T cells and tumor regression. Importantly, the infiltration of cytotoxic T cells was accompanied by the mobilization of inflammatory monocytes that significantly contributed to tumor regression. Thus, the specific targeting of CD163
TAMs reeducates the tumor immune microenvironment and promotes both myeloid and T cell-mediated antitumor immunity, illustrating the importance of selective targeting of tumor-associated myeloid cells in a therapeutic context.
PDF
