Drug-induced splenic enlargement

Possible pathogenic mechanisms for doxorubicin-induced splenic atrophy in a human breast cancer xenograft mouse model

Doxorubicin-based chemotherapy is a widely used first-line treatment for breast cancer, yet it is associated with various side effects, including splenic atrophy. However, the pathogenic mechanisms underlying doxorubicin-induced atrophy of the spleen remain unclear. This study investigates that doxorubicin treatment leads to splenic atrophy through several interconnected pathways involving histological changes, an inflammatory response, and apoptosis. Immunohistochemical and western blot analyses revealed reduced size of white and red pulp, decreased cellularity, amyloidosis, and fibrotic remodeling in the spleen following doxorubicin treatment. Additionally, increased secretion of pro-inflammatory cytokines was detected using an antibody array and enzyme-linked immunosorbent assay (ELISA), which triggers inflammation through the regulation of signal transducer and activator of transcription 3 (STAT3) and nuclear factor-kappa B (NF-κB) signaling pathways. Further analysis revealed that the loss of regulators and effectors of the oxidative defense system, including sirtuin (Sirt)3, Sirt5, superoxide dismutase (SOD)1, and SOD2, was implicated in the upstream regulation of caspase-dependent cellular apoptosis. These findings provide insights on the pathogenic mechanisms underlying doxorubicin-induced splenic atrophy and suggest that further investigation may be warranted to explore strategies for managing potential side effects in breast cancer patients treated with doxorubicin.

MALDI Imaging Mass Spectrometry Visualizes the Distribution of Antidepressant Duloxetine and Its Major Metabolites in Mouse Brain, Liver, Kidney, and Spleen Tissues

Imaging mass spectrometry (IMS) is a powerful tool for mapping the spatial distribution of unlabeled drugs and metabolites that may find application in assessing drug delivery, explaining drug efficacy, and identifying potential toxicity. This study focuses on determining the spatial distribution of the antidepressant duloxetine, which is widely prescribed despite common adverse effects (liver injury, constant headaches) whose mechanisms are not fully understood. We used high-resolution IMS with matrix-assisted laser desorption/ionization to examine the distribution of duloxetine and its major metabolites in four mouse organs where it may contribute to efficacy or toxicity: brain, liver, kidney, and spleen. In none of these tissues is duloxetine or its metabolites homogeneously distributed, which has implications for both efficacy and toxicity. We found duloxetine to be similarly distributed in spleen red pulp and white pulp but differentially distributed in different anatomic regions of the liver, kidney, and brain, with dose-dependent patterns. Comparison with hematoxylin and eosin staining of tissue sections reveals that the ion images of endogenous lipids help delineate anatomic regions in the brain and kidney, while heme ion images assist in differentiating regions within the spleen. These endogenous metabolites may serve as a valuable resource for examining the spatial distribution of other drugs in tissues when staining images are not available. These findings may facilitate future mechanistic studies of the therapeutic and adverse effects of duloxetine. In the current work, we did not perform absolute quantification of duloxetine, which will be reported in due course. SIGNIFICANCE STATEMENT: The study utilized imaging mass spectrometry to examine the spatial distribution of duloxetine and its primary metabolites in mouse brain, liver, kidney, and spleen. These results may pave the way for future investigations into the mechanisms behind duloxetine's therapeutic and adverse effects. Furthermore, the mass spectrometry images of specific endogenous metabolites such as heme could be valuable in analyzing the spatial distribution of other drugs within tissues in scenarios where histological staining images are unavailable.

Preclinical Activity and Pharmacokinetic/Pharmacodynamic Relationship for a Series of Novel Benzenesulfonamide Perforin Inhibitors

Perforin is a key effector of lymphocyte-mediated cell death pathways and contributes to transplant rejection of immunologically mismatched grafts. We have developed a novel series of benzenesulfonamide (BZS) inhibitors of perforin that can mitigate graft rejection during allogeneic bone marrow/stem cell transplantation. Eight such perforin inhibitors were tested for their murine pharmacokinetics, plasma protein binding, and their ability to block perforin-mediated lysis in vitro and to block the rejection of major histocompatibility complex (MHC)-mismatched mouse bone marrow cells. All compounds showed >99% binding to plasma proteins and demonstrated perforin inhibitory activity in vitro and in vivo. A lead compound, compound 1, that showed significant increases in allogeneic bone marrow preservation was evaluated for its plasma pharmacokinetics and in vivo efficacy at multiple dosing regimens to establish a pharmacokinetic/pharmacodynamic (PK/PD) relationship. The strongest PK/PD correlation was observed between perforin inhibition in vivo and time that total plasma concentrations remained above 900 μM, which correlates to unbound concentrations similar to 3× the unbound in vitro IC₉₀ of compound 1. This PK/PD relationship will inform future dosing strategies of BZS perforin inhibitors to maintain concentrations above 3× the unbound IC₉₀ for as long as possible to maximize efficacy and enhance progression toward clinical evaluation.

A polymer-based anti-quorum catheter coating to challenge MDR Staphylococcus aureus: in vivo and in vitro approaches

BACKGROUND

MDR Staphylococcus aureus is a major aetiological agent of catheter-associated infections. A quorum sensing targeted drug development approach proves to be an effective alternative strategy to combat such infections.

METHODS

Intravenous catheters were coated with polymethacrylate copolymers loaded with the antivirulent compound 2-[(methylamino)methyl]phenol (2MAMP). The in vitro drug release profile and kinetics were established. The anti-biofilm effect of the coated catheters was tested against clinical isolates of MDR S. aureus. The in vivo studies were carried out using adult male Wistar rats by implanting coated catheters in subcutaneous pockets. Histopathological analysis was done to understand the immunological reactions induced by 2MAMP.

RESULTS

A uniform catheter coating of thickness 0.1 mm was achieved with linear sustained release of 2MAMP for 6 h. The coating formulation was cytocompatible. The in vitro and in vivo anti-adherence studies showed reduced bacterial accumulation in coated catheters after 48 h. The histopathological results confirmed that the coated catheter did not bring about any adverse inflammatory response.

CONCLUSIONS

The developed anti-quorum-coated catheter that is non-toxic and biocompatible has the potential to be used in other medical devices, thereby preventing catheter-associated infections.

Shell-Free Copper Indium Sulfide Quantum Dots Induce Toxicity in Vitro and in Vivo

Semiconductor quantum dots (QDs) are attractive fluorescent contrast agents for in vivo imaging due to their superior photophysical properties, but traditional QDs comprise toxic materials such as cadmium or lead. Copper indium sulfide (CuInS₂, CIS) QDs have been posited as a nontoxic and potentially clinically translatable alternative; however, previous in vivo studies utilized particles with a passivating zinc sulfide (ZnS) shell, limiting direct evidence of the biocompatibility of the underlying CIS. For the first time, we assess the biodistribution and toxicity of unshelled CIS and partially zinc-alloyed CISZ QDs in a murine model. We show that bare CIS QDs breakdown quickly, inducing significant toxicity as seen in organ weight, blood chemistry, and histology. CISZ demonstrates significant, but lower, toxicity compared to bare CIS, while our measurements of core/shell CIS/ZnS are consistent with literature reports of general biocompatibility. In vitro cytotoxicity is dose-dependent on the amount of metal released due to particle degradation, linking degradation to toxicity. These results challenge the assumption that removing heavy metals necessarily reduces toxicity: indeed, we find comparable in vitro cytotoxicity between CIS and CdSe QDs, while CIS caused severe toxicity in vivo compared to CdSe. In addition to highlighting the complexity of nanotoxicity and the differences between the in vitro and in vivo outcomes, these unexpected results serve as a reminder of the importance of assessing the biocompatibility of core QDs absent the protective ZnS shell when making specific claims of compositional biocompatibility.

Vinblastine-Loaded Nanoparticles with Enhanced Tumor-Targeting Efficiency and Decreasing Toxicity: Developed by One-Step Molecular Imprinting Process

Molecularly imprinted polymers have exhibited good performance as carriers on drug loading and sustained release. In this paper, vinblastine (VBL)-loaded polymeric nanoparticles (VBL-NPs) were prepared by a one-step molecular imprinting process, avoiding the waste and incomplete removal of the template, and evaluated as targeting carriers for VBL delivery after modification. Using acryloyl amino acid comonomers and disulfide cross-linkers, VBL-NPs were synthesized and then conjugated with poly(ethylene glycol)-folate. The dynamic size of the obtained VBL-NPs-PEG-FA was 258.3 nm (PDI = 0.250), and the encapsulation efficiency was 45.82 ± 1.45%. The nanoparticles of VBL-NPs-PEG-FA were able to completely release VBL during 48 h under a mimic tumor intracellular condition (pH 4.5, 10 mM glutathione (GSH)), displaying significant redox responsiveness, whereas the release rates were much slower in the mimic body liquid (pH 7.4, 2 μM GSH) and tumor extracellular environment (pH 6.5, 2 μM GSH). Furthermore, the carriers NPs-PEG-FA, prepared without VBL, showed satisfactory intrinsic hemocompatibility, cellular compatibility, and tumor-targeting properties: they could rapidly and efficiently accumulate to folate receptor positive Hela cells and then internalized via receptor-mediated endocytosis, and the retention in tumor tissues could last for over 48 h. Interestingly, VBL-NPs-PEG-FA could evidently increase the accumulation of VBL in tumor tissues while decreasing the distribution of VBL in organs, exert similar anticancer efficacy against Hela tumors in the xenograft model of nude mice to VBL injection, and significantly improve the abnormality of liver and spleen observed in VBL injection. VBL-NPs-PEG-FA has the potential to be the delivery carrier for VBL by enhancing the tumor-targeting efficacy of VBL and decreasing toxicity to normal tissues.

Subacute treatment of carprofen facilitate splenocardiac resolution deficit in cardiac injury

Inflammation-limiting nonsteroidal pain relievers magnify myocardial infarction (MI) incidences and increase re-admission events in heart failure (HF) patients. However, the molecular and cellular mechanism of this provocative adverse effect is unclear. Our goal was to determine whether carprofen (CAP) impedes splenic leukocyte-directed acute inflammation-resolving response in cardiac injury. After subacute CAP treatment, mice were subjected to permanent coronary ligation maintaining MI- and naïve-controls. Spleen and left ventricle (LV) leukocytes were quantitated using flow cytometry pre- and 24 h post-MI. The inflammation resolution mediators were quantified using mass spectrometry while splenocardiac apoptosis and leukocyte phagocytosis were measured by immunofluorescence and ImageStream, respectively. Subacute CAP treatment promoted strain and cardiac dysfunction before MI and coronary occlusion showed signs of acute HF in CAP and MI-controls. Subacute CAP-injected mice had pre-activated splenic neutrophils, an over activated "don't eat me" signal (CD47) with reduced total Mϕs (F4/80⁺ ) and reparative Mϕs (F4/80/Ly6C^lo /CD206) compared with control in LV and spleen. Post-MI, CAP pre-activated neutrophils (Ly6G⁺ ) were intensified and reduced reparative neutrophils (Ly6G⁺ /CD206⁺ ) and Mϕs (F4/80/Ly6C^lo ) in LV was indicative of non-resolving inflammation compared with MI-control. Subacute CAP treatment deferred neutrophil phagocytosis functions in the spleen and LV and was more evident post-MI compared with MI-control. CAP pre-activated splenic neutrophils that tailored the Mϕ phagocytosis thereby increased splenocardiac leukocyte death. CAP over amplified COX-1 and COX-2 compared with MI-control and failed to limit prostaglandins and thromboxane in post-MI setting. Further, CAP reduced cardiac-protective epoxyeicosatrienoic acids and over amplified pyrogenic inflammatory cytokines and reduced reparative cytokines, thereby non-resolving inflammation.

Lactonic Sophorolipids Increase Tumor Burden in Apcmin+/- Mice

Sophorolipids (SL) are amphiphilic biosurfactant molecules consisting of a disaccharide sophorose with one fatty acid at the C1 position and optional acetylation at the C6’and C6” positions. They exist in a closed ring lactonic (LSL) or open acidic (ASL) structure Sophorolipids are produced in crude mixtures in economically viable amounts by the yeast Starmerella bombicola and used in a variety of consumer products. Varying levels of anti- proliferative and anti-cancer activity of crude sophorolipid mixtures are described in a number of tumor cell lines in vitro. However, significant inter-study variation exists in the composition of sophorolipid species as well as other biologically active compounds in these mixtures, which makes interpretation of in vitro and in vivo studies difficult. We produced a 96% pure C18:1 lactonic sophorolipid that dose-dependently reduces the viability of colorectal cancer, as well as normal human colonic and lung cell lines in vitro. Oral administration of vehicle-only; or lactonic sophorolipids (50 mg/kg for 70 days), to Apc^min+/- mice resulted in an increase in the number (55.5 ± 3.3 vs 70.50 ± 7.8: p < 0.05) and size (modal size 2mm vs 4mm) of intestinal polyps. Lactonic administration resulted in a systematic effect via reduced hematocrit (49.5 ± 1.0 vs 28.2 ± 2.0 vs: p<0.03) and splenomegaly (0.56 ± 0.03g vs 0.71 ± 0.04g; p<0.01) confirming exacerbation of disease progression in this model.

Transcriptional Profiling of Dibenzo[def,p]chrysene-induced Spleen Atrophy Provides Mechanistic Insights into its Immunotoxicity in MutaMouse

Dibenzo[def,p]chrysene (DBC) is the most carcinogenic polycyclic aromatic hydrocarbon (PAH) examined to date. We investigated the immunotoxicity of DBC, manifested as spleen atrophy, following acute exposure of adult MutaMouse males by oral gavage. Mice were exposed to 0, 2.0, 6.2, or 20.0 mg DBC /kg-bw per day, for 3 days. Genotoxic endpoints (DBC-DNA adducts and lacZ mutant frequency in spleen and bone marrow, and red blood cell micronucleus frequency) and global gene expression changes were measured. All of the genotoxicity measures increased in a dose-dependent manner in spleen and bone marrow. Gene expression analysis showed that DBC activates p53 signaling pathways related to cellular growth and proliferation, which was evident even at the low dose. Strikingly, the expression profiles of DBC exposed mouse spleens were highly inversely correlated with the expression profiles of the only published toxicogenomics dataset of enlarged mouse spleen. This analysis suggested a central role for Bnip3l, a pro-apoptotic protein involved in negative regulation of erythroid maturation. RT-PCR confirmed expression changes in several genes related to apoptosis, iron metabolism, and aryl hydrocarbon receptor signaling that are regulated in the opposite direction during spleen atrophy versus benzo[a]pyrene-mediated splenomegaly. In addition, benchmark dose modeling of toxicogenomics data yielded toxicity estimates that are very close to traditional toxicity endpoints. This work illustrates the power of toxicogenomics to reveal rich mechanistic information for immunotoxic compounds and its ability to provide information that is quantitatively similar to that derived from standard toxicity methods in health risk assessment.

Hepatic Lesions Caused by Large Granular Lymphocyte Leukemia in Fischer 344 Rats: Similar Morphologic Features and Morphogenesis to Those of Nodular Regenerative Hyperplasia (NRH) in the Human Liver

To characterize the hepatic lesions in Fischer 344 (F344) rats afflicted with large granular lymphocyte (LGL) leukemia, the livers of rats with LGL leukemia at various stages were examined histopathologically and immunohistochemically. The morphologic features in the livers of rats afflicted with LGL leukemia were diffuse, uniform-sized, granular, or micronodular lesions consisting of hepatocytes showing centrilobular atrophy and perilobular hypertrophy (CAPH) without fibrosis. With progression in the stage of the LGL leukemia, the severity of the CAPH of hepatocytes increased resulting in fatty change and/or single-cell necrosis, along with compensatory hyperplasia of the hepatocytes, finally resulting in lesions similar to those seen in nodular regenerative hyperplasia (NRH) in the human liver. The CAPH of hepatocytes was a nonspecific tissue adaptation against ischemia or hypoxemia and/or imbalance in blood supply due to disturbance in the portal circulation and hemolytic anemia induced by the leukemia cells. In addition, direct and/or indirect hepatocellular injuries by leukemia cells were considered to be necessary for the formation of human NRH-like lesions. Morphogenetic investigation of the livers of rats afflicted with LGL leukemia may be helpful to clarify the pathogenesis of NRH in the human liver.

Potential protective effect of sunitinib after administration of diclofenac: biochemical and histopathological drug-drug interaction assessment in a mouse model

Sunitinib is a tyrosine kinase inhibitor for GIST and advanced renal cell carcinoma. Diclofenac is used in cancer pain management. Coadministration may mediate P450 toxicity. We evaluate their interaction, assessing biomarkers ALT, AST, BUN, creatinine, and histopathological changes in the liver, kidney, heart, brain, and spleen. ICR mice (male, n = 6 per group/dose) were administered saline (group A) or 30 mg/kg diclofenac ip (group B), or sunitinib po at 25, 50, 80, 100, 140 mg/kg (group C) or combination of diclofenac (30 mg/kg, ip) and sunitinib (25, 50, 80, 100, 140 mg/kg po). Diclofenac was administered 15 min before sunitinib, mice were euthanized 4 h post-sunitinib dose, and biomarkers and tissue histopathology were assessed. AST was 92.2 ± 8.0 U/L in group A and 159.7 ± 14.6 U/L in group B (p < 0.05); in group C, it the range was 105.1-152.6 U/L, and in group D, it was 156.0-209.5 U/L (p < 0.05). ALT was 48.9 ± 1.6 U/L (group A), 95.1 ± 4.5 U/L (p < 0.05) in group B, and 50.5-77.5 U/L in group C and 82.3-115.6 U/L after coadministration (p < 0.05). Renal function biomarker BUN was 16.3 ± 0.6 mg/dl (group A) and increased to 29.9 ± 2.6 mg/dl in group B (p < 0.05) and it the range was 19.1-33.3 mg/dl (p < 0.05) and 26.9-40.8 mg/dl in groups C and D, respectively. Creatinine was 5.9 pmol/ml in group A; 6.2 pmol/ml in group B (p < 0.01), and the range was 6.0-6.2 and 6.2-6.4 pmol/ml in groups C and D, respectively (p < 0.05 for D). Histopathological assessment (vascular and inflammation damages) showed toxicity in group B (p < 0.05) and mild toxicity in group C. Damage was significantly lesser in group D than group B (p < 0.05). Spleen only showed toxicity after coadministration. These results suggest vascular and inflammation protective effects of sunitinib, not shown after biomarker analysis.