Peritoneal macrophages mediated delivery of chitosan/siRNA nanoparticle to the lesion site in a murine radiation-induced fibrosis model

Obstructive nephropathy and molecular pathophysiology of renal interstitial fibrosis

The kidneys play a key role in maintaining total body homeostasis. The complexity of this task is reflected in the unique architecture of the organ. Ureteral obstruction greatly affects renal physiology by altering hemodynamics, changing glomerular filtration and renal metabolism, and inducing architectural malformations of the kidney parenchyma, most importantly renal fibrosis. Persisting pathological changes lead to chronic kidney disease, which currently affects ∼10% of the global population and is one of the major causes of death worldwide. Studies on the consequences of ureteral obstruction date back to the 1800s. Even today, experimental unilateral ureteral obstruction (UUO) remains the standard model for tubulointerstitial fibrosis. However, the model has certain limitations when it comes to studying tubular injury and repair, as well as a limited potential for human translation. Nevertheless, ureteral obstruction has provided the scientific community with a wealth of knowledge on renal (patho)physiology. With the introduction of advanced omics techniques, the classical UUO model has remained relevant to this day and has been instrumental in understanding renal fibrosis at the molecular, genomic, and cellular levels. This review details key concepts and recent advances in the understanding of obstructive nephropathy, highlighting the pathophysiological hallmarks responsible for the functional and architectural changes induced by ureteral obstruction, with a special emphasis on renal fibrosis.

A pH-responsive T1-T2 dual-modal MRI contrast agent for cancer imaging

Magnetic resonance imaging (MRI) is a non-invasive imaging technology to diagnose health conditions, showing the weakness of low sensitivity. Herein, we synthesize a contrast agent, SPIO@SiO₂@MnO₂, which shows decreased T₁ and T₂ contrast intensity in normal physiological conditions. In the acid environment of tumor or inflamed tissue, the manganese dioxide (MnO₂) layer decomposes into magnetically active Mn²⁺ (T₁-weighted), and the T₁ and T₂ signals are sequentially recovered. In addition, both constrast quenching-activation degrees of T₁ and T₂ images can be accurately regulated by the silicon dioxide (SiO₂) intermediate layer between superparamagnetic iron oxide (SPIO) and MnO₂. Through the "dual-contrast enhanced subtraction" imaging processing technique, the contrast sensitivity of this MRI contrast agent is enhanced to a 12.3-time difference between diseased and normal tissue. Consequently, SPIO@SiO₂@MnO₂ is successfully applied to trace the tiny liver metastases of approximately 0.5 mm and monitor tissue inflammation.

Chitosan-Gelatin-EGCG Nanoparticle-Meditated LncRNA TMEM44-AS1 Silencing to Activate the P53 Signaling Pathway for the Synergistic Reversal of 5-FU Resistance in Gastric Cancer

Chemoresistance is one of the leading causes of therapeutic failure in gastric cancer (GC) treatment. Recent studies have shown lncRNAs play pivotal roles in regulating GC chemoresistance. Nanocarriers delivery of small interfering RNAs (siRNAs) to silence cancer-related genes has become a novel approach to cancer treatment research. However, finding target genes and developing nanosystems capable of selectively delivering siRNAs for disease treatment remains a challenge. In this study, a novel lncRNA TMEM44-AS1 that is related to 5-FU resistance is identified. TMEM44-AS1 has the ability to bind to and sponge miR-2355-5p, resulting in the upregulated PPP1R13L expression and P53 pathway inhibition. Next, a new nanocarrier called chitosan-gelatin-EGCG (CGE) is developed, which has a higher gene silencing efficiency than lipo2000, to aid in the delivery of a si-TMEM44-AS1 can efficiently silence TMEM44-AS1 expression to synergistically reverse 5-FU resistance in GC, leading to a markedly enhanced 5-FU therapeutic effect in a xenograft mouse model of GC. These findings indicate that TMEM44-AS1 may estimate 5-FU therapy outcome among GC cases, and that systemic si-TMEM44-AS1 delivery combined with 5-FU therapy is significant in the treatment of patients with recurrent GC.

Current Development of Nano-Drug Delivery to Target Macrophages

Macrophages are the most important innate immune cells that participate in various inflammation-related diseases. Therefore, macrophage-related pathological processes are essential targets in the diagnosis and treatment of diseases. Since nanoparticles (NPs) can be preferentially taken up by macrophages, NPs have attracted most attention for specific macrophage-targeting. In this review, the interactions between NPs and the immune system are introduced to help understand the pharmacokinetics and biodistribution of NPs in immune cells. The current design and strategy of NPs modification for specific macrophage-targeting are investigated and summarized.

Assessment of Physicochemical and In Vivo Biological Properties of Polymeric Nanocapsules Based on Chitosan and Poly(N-vinyl pyrrolidone-alt-itaconic anhydride)

Drug delivery is an important field of nanomedicine, and its aim is to deliver specific active substances to a precise site of action in order to produce a desired pharmacological effect. In the present study nanocapsules were obtained by a process of interfacial condensation between chitosan (dissolved in the aqueous phase) and poly(N-vinyl pyrrolidone-alt-itaconic anhydride), a highly reactive copolymer capable of easily opening the anhydride ring under the action of amine groups of chitosan. The formed amide bonds led to the formation of a hydrogel membrane. The morphology of the obtained nanocapsules, their behavior in aqueous solution of physiological pH, and their ability to encapsulate and release a model drug can be modulated by the parameters of the synthesis process, such as the molar ratio between functional groups of polymers and the ratio of the phases in which the polymers are solubilized. Although a priori both polymers are biocompatible, this paper reports the results of a very detailed in vivo study conducted on experimental animals which have received the obtained nanocapsules by three administration routes—intraperitoneal, subcutaneous, and oral. The organs taken from the animals’ kidney, liver, spleen, and lung and analyzed histologically demonstrated the ability of nanocapsules to stimulate the monocytic macrophage system without producing inflammatory changes. Moreover, their in vivo behavior has been shown to depend not only on the route of administration but also on the interaction with the cells of the organs with which they come into contact. The results clearly argue the biocompatibility of nanocapsules and hence the possibility of their safe use in biomedical applications.

Targeted delivery of celastrol to renal interstitial myofibroblasts using fibronectin-binding liposomes attenuates renal fibrosis and reduces systemic toxicity

Renal fibrosis often occurs in chronic kidney disease, and effective treatment is needed. Celastrol (CEL) may attenuate renal fibrosis, but it distributes throughout the body, leading to severe systemic toxicities. Here we designed a system to deliver CEL specifically to interstitial myofibroblasts, which is a key driver of renal fibrogenesis. Fibronectin is highly expressed in fibrotic kidney. The pentapeptide CREKA, which specifically binds fibronectin, was conjugated to PEGylated liposomes (CREKA-Lip). CREKA-coupled liposomes significantly increased the uptake of unmodified liposomes by activated NRK-49F renal fibroblasts. Systemic administration of CREKA-Lip to mice led to their accumulation in fibrotic kidney, where they were specifically internalized by interstitial myofibroblasts. Loading CEL into CREKA-Lip effectively inhibited the activation and proliferation of NRK-49F cells in vitro, and they markedly alleviated renal fibrosis, injury and inflammation induced by unilateral ureteral obstruction in mice. Besides, CEL-loaded CREKA-Lip was associated with significantly lower toxicity to major organs than free CEL. These results suggest that encapsulating CEL in CREKA-Lip can increase its therapeutic efficacy and reduce its systemic toxicity as a potential treatment for renal fibrosis.

The CD73/Ado System-A New Player in RT Induced Adverse Late Effects

Radiotherapy (RT) is a central component of standard treatment for many cancer patients. RT alone or in multimodal treatment strategies has a documented contribution to enhanced local control and overall survival of cancer patients, and cancer cure. Clinical RT aims at maximizing tumor control, while minimizing the risk for RT-induced adverse late effects. However, acute and late toxicities of IR in normal tissues are still important biological barriers to successful RT: While curative RT may not be tolerable, sub-optimal tolerable RT doses will lead to fatal outcomes by local recurrence or metastatic disease, even when accepting adverse normal tissue effects that decrease the quality of life of irradiated cancer patients. Technical improvements in treatment planning and the increasing use of particle therapy have allowed for a more accurate delivery of IR to the tumor volume and have thereby helped to improve the safety profile of RT for many solid tumors. With these technical and physical strategies reaching their natural limits, current research for improving the therapeutic gain of RT focuses on innovative biological concepts that either selectively limit the adverse effects of RT in normal tissues without protecting the tumor or specifically increase the radiosensitivity of the tumor tissue without enhancing the risk of normal tissue complications. The biology-based optimization of RT requires the identification of biological factors that are linked to differential radiosensitivity of normal or tumor tissues, and are amenable to therapeutic targeting. Extracellular adenosine is an endogenous mediator critical to the maintenance of homeostasis in various tissues. Adenosine is either released from stressed or injured cells or generated from extracellular adenine nucleotides by the concerted action of the ectoenzymes ectoapyrase (CD39) and 5′ ectonucleotidase (NT5E, CD73) that catabolize ATP to adenosine. Recent work revealed a role of the immunoregulatory CD73/adenosine system in radiation-induced fibrotic disease in normal tissues suggesting a potential use as novel therapeutic target for normal tissue protection. The present review summarizes relevant findings on the pathologic roles of CD73 and adenosine in radiation-induced fibrosis in different organs (lung, skin, gut, and kidney) that have been obtained in preclinical models and proposes a refined model of radiation-induced normal tissue toxicity including the disease-promoting effects of radiation-induced activation of CD73/adenosine signaling in the irradiated tissue environment. However, expression and activity of the CD73/adenosine system in the tumor environment has also been linked to increased tumor growth and tumor immune escape, at least in preclinical models. Therefore, we will discuss the use of pharmacologic inhibition of CD73/adenosine-signaling as a promising strategy for improving the therapeutic gain of RT by targeting both, malignant tumor growth and adverse late effects of RT with a focus on fibrotic disease. The consideration of the therapeutic window is particularly important in view of the increasing use of RT in combination with various molecularly targeted agents and immunotherapy to enhance the tumor radiation response, as such combinations may result in increased or novel toxicities, as well as the increasing number of cancer survivors.

Loss of CD73 prevents accumulation of alternatively activated macrophages and the formation of prefibrotic macrophage clusters in irradiated lungs

While radiotherapy is a mainstay for cancer therapy, pneumonitis and fibrosis constitute dose-limiting side effects of thorax and whole body irradiation. So far, the contribution of immune cells to disease progression is largely unknown. Here we studied the role of ecto-5'-nucelotidase (CD73)/adenosine-induced changes in the myeloid compartment in radiation-induced lung fibrosis. C57BL/6 wild-type or CD73^-/- mice received a single dose of whole thorax irradiation (WTI, 15 Gy). Myeloid cells were characterized in flow cytometric, histologic, and immunohistochemical analyses as well as RNA analyses. WTI induced a pronounced reduction of alveolar macrophages in both strains that recovered within 6 wk. Fibrosis development in wild-type mice was associated with a time-dependent deposition of hyaluronic acid (HA) and increased expression of markers for alternative activation on alveolar macrophages. These include the antiinflammatory macrophage mannose receptor and arginase-1. Further, macrophages accumulated in organized clusters and expressed profibrotic mediators at ≥25 wk after irradiation (fibrotic phase). Irradiated CD73^-/- mice showed an altered regulation of components of the HA system and no clusters of alternatively activated macrophages. We speculate that accumulation of alternatively activated macrophages in organized clusters represents the origins of fibrotic foci after WTI and is promoted by a cross-talk between HA, CD73/adenosine signaling, and other profibrotic mediators.-De Leve, S., Wirsdörfer, F., Cappuccini, F., Schütze, A., Meyer, A. V., Röck, K., Thompson, L. F., Fischer, J. W., Stuschke, M., Jendrossek, V. Loss of CD73 prevents accumulation of alternatively activated macrophages and the formation of prefibrotic macrophage clusters in irradiated lungs.

Modulation of Macrophage Functional Polarity towards Anti-Inflammatory Phenotype with Plasmid DNA Delivery in CD44 Targeting Hyaluronic Acid Nanoparticles

The purpose of this study was to modulate macrophage polarity from the pro-inflammatory M1 to anti-inflammatory M2 phenotype using plasmid DNA (pDNA) expressing interleukin-4 (IL4) or interleukin-10 (IL10)-encapsulated in hyaluronic acid-poly(ethyleneimine) (HA-PEI) nanoparticles (NPs). The HA-PEI/pDNA NPs with spherical shape, average size of 186 nm were efficiently internalized by J774A.1 macrophages. Transfection of HA-PEI/pDNA-IL4 and HA-PEI/pDNA-IL10 NPs increased IL4 and IL10 gene expression in J774 macrophages which could re-program the macrophages from M1 to M2 phenotype as evidenced by a significant increase in the Arg/iNOS level, and upregulation of CD206 and CD163 compared to untreated macrophages. Following intraperitoneal (IP) injection to C57BL/6 mice, HA-PEI NPs effectively targeted peritoneal macrophages over-expressing CD44 receptor. In an in vivo model of stimulated peritoneal macrophages, IP administration of HA-PEI/pDNA-IL4 and HA-PEI/pDNA-IL10 to C57BL/6 mice significantly increased the Arg/iNOS ratio and CD163 expression in the cells. Furthermore, HA-PEI/pDNA-IL10 NPs significantly increased peritoneal and serum IL10 levels which effectively suppressed LPS-induced inflammation by reducing level of TNF-α and IL-1β in peritoneal macrophages and in the peritoneal fluid. The results demonstrated that pDNA-IL10-encapsulate HA-PEI NPs skewed macrophage functional polarity from M1 toward an anti-inflammatory M2 phenotype which may be a promising platform for the treatment of inflammatory diseases.

Chitosan polyplex mediated delivery of miRNA-124 reduces activation of microglial cells in vitro and in rat models of spinal cord injury

Traumatic injury to the central nervous system (CNS) is further complicated by an increase in secondary neuronal damage imposed by activated microglia/macrophages. MicroRNA-124 (miR-124) is responsible for mouse monocyte quiescence and reduction of their inflammatory cytokine production. We describe the formulation and ex vivo transfection of chitosan/miR-124 polyplex particles into rat microglia and the resulting reduction of reactive oxygen species (ROS) and TNF-α and lower expression of MHC-II. Upon microinjection into uninjured rat spinal cords, particles formed with Cy3-labeled control sequence RNA, were specifically internalized by OX42 positive macrophages and microglia cells. Alternatively particles injected in the peritoneum were transported by macrophages to the site of spinal cord injury 72 h post injection. Microinjections of chitosan/miR-124 particles significantly reduced the number of ED-1 positive macrophages in the injured spinal cord. Taken together, these data present a potential treatment technique to reduce inflammation for a multitude of CNS neurodegenerative conditions.

FROM THE CLINICAL EDITOR

The treatment of spinal cord injury remains an unresolved problem. Secondary damage is often the result of inflammation caused by activated microglia and/or macrophages. In this article, the authors developed their formulation of chitosan/miR-124 polyplex particles and investigated their use in the suppression of neuronal inflammation. This exciting data may provide a new horizon for patients who suffer from spinal cord injury.

Intracellular sorting of differently charged chitosan derivatives and chitosan-based nanoparticles

Chitosan (Chi) is a biodegradable nontoxic polycation with multiple reactive groups that is easily used to obtain derivatives with a desired charge and hydrophobic properties. The aim of this work was to study the intracellular traffic of positively charged hexanoyl-chitosan (HC) or HC-based nanoparticles (HCNPs) and negatively charged succinoyl-chitosan (SC) and SCNPs in epithelial and macrophage cell lines. By using flow cytometry we demonstrated that positively charged HC adhered to cell membranes quicker and more efficiently than negatively charged SC or NPs. However confocal studies showed that SC and SCNPs penetrated cells much more efficiently than HC while HCNPs did not enter the epithelial cells. Macrophages also phagocyted better negatively charged material but were able to engulf both HC and HCNPs. Upon entering the cells, SC and SCNPs were co-localized with endosomes and lysosomes while HC was found in mitochondria and, to a lesser extent, in lysosomes of epithelial cells. Macrophages, RAW264.7, more efficiently transported all Chi samples to the lysosomal compartment while some positively charged material was still found in mitochondria. Incubation of Chi derivatives and ChiNPs at pH specific to mitochondria (8.0) and lysosomes (4.5) demonstrated the neutralization of Chi charge. We concluded that epithelial cells and, to a lesser extent, macrophages sort charged material to the organelles neutralizing Chi charge.

Chitosan/siRNA nanoparticles targeting cyclooxygenase type 2 attenuate unilateral ureteral obstruction-induced kidney injury in mice

Cyclooxygenase type 2 (COX-2) plays a predominant role in the progression of kidney injury in obstructive nephropathy. The aim of this study was to test the efficacy of chitosan/small interfering RNA (siRNA) nanoparticles to knockdown COX-2 specifically in macrophages to prevent kidney injury induced by unilateral ureteral obstruction (UUO). Using optical imaging techniques and confocal microscopy, we demonstrated that chitosan/siRNA nanoparticles accumulated in macrophages in the obstructed kidney. Consistent with the imaging data, the obstructed kidney contained a higher amount of siRNA and macrophages. Chitosan-formulated siRNA against COX-2 was evaluated on RAW macrophages demonstrating reduced COX-2 expression and activity after LPS stimulation. Injection of COX-2 chitosan/siRNA nanoparticles in mice subjected to three-day UUO diminished the UUO-induced COX-2 expression. Likewise, macrophages in the obstructed kidney had reduced COX-2 immunoreactivity, and histological examination showed lesser tubular damage in COX-2 siRNA-treated UUO mice. Parenchymal inflammation, assessed by tumor necrosis factor-alpha (TNF-α) and interleukin 6 mRNA expression, was attenuated by COX-2 siRNA. Furthermore, treatment with COX-2 siRNA reduced heme oxygenase-1 and cleaved caspase-3 in UUO mice, indicating lesser oxidative stress and apoptosis. Our results demonstrate a novel strategy to prevent UUO-induced kidney damage by using chitosan/siRNA nanoparticles to knockdown COX-2 specifically in macrophages.

Macrophage-mediated nanoparticle delivery to the periodontal lesions in established murine model via Pg-LPS induction

We established a murine periodontitis model by local injection of lipopolysaccharide of Porphyromonas gingivalis (Pg-LPS) into the gingival sulcus of mandibular left incisor four times with 48-h interval. The histological examination of the periodontal tissues demonstrated that significant loss of periodontal bone and ligaments was observed in the lesion side with abundant inflammatory cell infiltration. Two days after the last injection, Cy5-labelled siRNA/chitosan particles were injected intraperitoneally (ip). The chitosan/siRNA particles were taken up by peritoneal macrophages, which subsequently migrated to the inflamed gingival area evaluated by in vivo imaging. The localization of macrophages in the inflamed region was further confirmed by immunofluorescent staining. The present report demonstrates that intragingival injection of Pg-LPS can be used to create an experimental model of periodontal inflammation in mice and that recruitment of macrophages with chitosan/siRNA nanoparticles to the inflamed area opens the possibility of an RNAi-based therapeutic approach using chitosan as a carrier in periodontitis.

Chitosan hydrogel as siRNA vector for prolonged gene silencing

Background

The periodontitis is one of the most prevalent diseases with alveolar resorption in adult people and is the main cause of the tooth loss. To investigate the possibility for protecting the loss of alveolar bone in periodontal diseases, a RNAi-based therapeutic strategy is applied for silencing RANK signaling using thermosensitive chitosan hydrogel as siRNA reservoir and vector.

Results

The thermosensitive chitosan hydrogel was formed from solution (PH = 7.2, at 4°C) at 37°C within 8 minutes. The degradation rates of hydrogel were ~50% and 5% (W remaining/W beginning) in the presence and absence of lysozyme, respectively, over a period of 20 days. The concurrent cumulative in vitro release of Cy3-labeled siRNA from the hydrogel was 50% and 17% over 14 days, with or without lysozyme digestion, respectively. High cell viability (>88%) was maintained for cells treated with hydrogel loaded with RANK specific siRNA and RANK knockdown was prolonged for up to 9 days when cells were incubated with siRNA/hydrogel complex. In vivo release of siRNA was investigated in a subcutaneous delivery setup in mice. The fluorescent signal from siRNA within hydrogel was remained for up to 14 days compared to less than one day for siRNA alone.

Conclusions

Chitosan hydrogel can potentially serve as a suitable reservoir and vector for local sustained delivery of siRNA in potential therapy.

Epigenetics in radiation-induced fibrosis

Radiotherapy is a major cancer treatment option but dose-limiting side effects such as late-onset fibrosis in the irradiated tissue severely impair quality of life in cancer survivors. Efforts to explain radiation-induced fibrosis, for example, by genetic variation remained largely inconclusive. Recently published molecular analyses on radiation response and fibrogenesis showed a prominent role of epigenetic gene regulation. This review summarizes the current knowledge on epigenetic modifications in fibrotic disease and radiation response, and it points out the important role for epigenetic mechanisms such as DNA methylation, microRNAs and histone modifications in the development of this disease. The synopsis illustrates the complexity of radiation-induced fibrosis and reveals the need for investigations to further unravel its molecular mechanisms. Importantly, epigenetic changes are long-term determinants of gene expression and can therefore support those mechanisms that induce and perpetuate fibrogenesis even in the absence of the initial damaging stimulus. Future work must comprise the interconnection of acute radiation response and long-lasting epigenetic effects in order to assess their role in late-onset radiation fibrosis. An improved understanding of the underlying biology is fundamental to better comprehend the origin of this disease and to improve both preventive and therapeutic strategies.

Chitosan nanoparticles for siRNA delivery: optimizing formulation to increase stability and efficiency

This study aims at developing chitosan-based nanoparticles suitable for an intravenous administration of small interfering RNA (siRNA) able to achieve (i) high gene silencing without cytotoxicity and (ii) stability in biological media including blood. Therefore, the influence of chitosan/tripolyphosphate ratio, chitosan physicochemical properties, PEGylation of chitosan as well as the addition of an endosomal disrupting agent and a negatively charged polymer was assessed. The gene silencing activity and cytotoxicity were evaluated on B16 melanoma cells expressing luciferase. We monitored the integrity and the size behavior of siRNA nanoparticles in human plasma using fluorescence fluctuation spectroscopy and single particle tracking respectively. The presence of PEGylated chitosan and poly(ethylene imine) was essential for high levels of gene silencing in vitro. Chitosan nanoparticles immediately released siRNA in plasma while the inclusion of hyaluronic acid and high amount of poly(ethylene glycol) in the formulation improved the stability of the particles. The developed formulations of PEGylated chitosan-based nanoparticles that achieve high gene silencing in vitro, low cytotoxicity and high stability in plasma could be promising for intravenous delivery of siRNA.