Recombinant human hyaluronidase PH20 does not stimulate an acute inflammatory response and inhibits lipopolysaccharide-induced neutrophil recruitment in the air pouch model of inflammation

Structural identification and quantification of unreported sialylated N-glycans in bovine testicular hyaluronidase by LC-ESI-HCD-MS/MS

Bovine testicular hyaluronidase (BTH), which accelerates the absorption and dispersion of drugs by decomposing hyaluronan in subcutaneous tissues, has been used in medical applications, including local anesthesia, ophthalmology, and dermatosurgery. The requirement of N-glycans for the activity of human hyaluronidase has been reported, and BTH has greater activity than human hyaluronidase. However, the N-glycan characteristics of BTH are unclear. From a commercial BTH source containing additional proteins, purified BTH (pBTH) was obtained using size exclusion chromatography, and the structures and quantities of its N-glycans were analyzed using liquid chromatography (LC)-electrospray ionization-higher energy collisional dissociation (HCD)-tandem mass spectrometry (MS/MS). In pBTH, 32 N-glycans were identified, with 12 sialylations (39.0% of total N-glycan content), nine core-fucosylations (31.5%), six terminal galactosylations (14.6%), five high-mannosylations (13.7%), and four bisecting N-acetylglucosamine structures (7.8%). The presence of sialylated glycopeptides in pBTH was confirmed by nano-LC-HCD-MS/MS analysis. The absolute quantity of all N-glycans was calculated as 1.4 pmol (0.6 pmol for sialylation) in pBTH (1.0 pmol). The sialylation level (related to half-life, thermal stability, resistance to proteolysis, and solubility) was 24.4 times higher than that of human hyaluronidase. The hyaluronan degradation activity of de-sialylated pBTH decreased to 41.2 ± 4.2%, showing that sialylated N-glycans were required for pBTH activity as well. This is the first study to identify and quantify 32 N-glycans of pBTH and investigate their structural roles in its activity. The presence of larger amounts of sialylated N-glycans in pBTH than in human hyaluronidase suggests a greater utilization of pBTH.

Characterization, Bioactivity, and Biodistribution of 35 kDa Hyaluronan Fragment

It has been reported that hyaluronic acid (HA) with a 35 kDa molecular weight (HA35) acts biologically to protect tissue from injury, but its biological properties are not yet fully characterized. This study aimed to evaluate the cellular effects and biodistribution of HA35 compared to HA with a 1600 kDa molecular weight (HA1600). We assessed the effects of HA35 and HA1600 on cell migration, NO and ROS generation, and gene expression in cultured macrophages, microglia, and lymphocytes. HA35 was separately radiolabeled with 99mTc and 125I and administered to C57BL/6J mice for in vivo biodistribution imaging. In vitro studies indicated that HA35 and HA1600 similarly enhanced cell migration through HA receptor binding mechanisms, reduced the generation of NO and ROS, and upregulated gene expression profiles related to cell signaling pathways in immune cells. HA35 showed a more pronounced effect in regulating a broader range of genes in macrophages and microglia than HA1600. Upon intradermal or intravenous administration, radiolabeled HA35 rapidly accumulated in the liver, spleen, and lymph nodes. In conclusion, HA35 not only exhibits effects on cellular bioactivity comparable to those of HA1600 but also exerts biological effects on a broader range of immune cell gene expression. The findings herein offer valuable insights for further research into the therapeutic potential of HA35 in inflammation-mediated tissue injury.

The Effect of Mechanical Stress on Hyaluronan Fragments' Inflammatory Cascade: Clinical Implications

It is a common experience, reported by patients who have undergone manual therapy that uses deep friction, to perceive soreness in treatment areas; however, it is still not clear what causes it and if it is therapeutically useful or a simple side effect. The purpose of this narrative review is to determine whether manual and physical therapies can catalyze an inflammatory process driven by HA fragments. The literature supports the hypothesis that mechanical stress can depolymerize into small pieces at low molecular weight and have a high inflammatory capacity. Many of these pieces are then further degraded into small oligosaccharides. Recently, it has been demonstrated that oligosaccharides are able to stop this inflammatory process. These data support the hypothesis that manual therapy that uses deep friction could metabolize self-aggregated HA chains responsible for increasing loose connective tissue viscosity, catalyzing a local HA fragment cascade that will generate soreness but, at the same time, facilitate the reconstitution of the physiological loose connective tissue properties. This information can help to explain the meaning of the inflammatory process as well as the requirement for it for the long-lasting resolution of these alterations.

Site-specific integration as an efficient method for production of recombinant human hyaluronidase PH20 in semi-adherent cells

PH20 is a hyaluronidase enzyme that can hydrolyze the glycosidic bond in hyaluronic acid as the major proteoglycan found in extracellular matrices. In the present study, we constructed and characterized two donor plasmids, one of them with one and the second with two PH20 expression cassettes. The expression vectors were site specifically integrated into the genome of HEK293T cells using PhiC31 integrase system to develop HEK293T stable cell lines secreting His-tagged recombinant human PH20 (rhPH20) in the culture supernatant. The produced rhPH20 was quantified using ELISA and turbidimetric assay tests, and its catalytic activity was also assessed by treating the mouse cumulus-oocyte complexes. Our results showed that the secreted rhPH20 in the culture supernatant had the specific activity of 16,660 IU/mg and the recombinant enzyme was able to remove the cumulus cells from oocytes. The results also indicated that phiC31 enzyme inserted the PH20-expressing donor vectors into the specific pseudo attP sites including 10q21.2 and 20q11.22 in the genome of the target cells with different copy numbers. Taken together, our findings demonstrate that PhiC31 integrase system is able to be applied as a robust tool for efficient production and secretion of soluble and active rhPH20 by HEK293T cells as a semi-adherent human cell line. KEY POINTS: • Efficient production of human recombinant PH20 in a semi-adherent human cell line • Successful application of PhiC31 integrase system for generation of stable recombinant clones • Use of a human cell line for expression of a recombinant human protein due to complex and efficient post-translational modifications and protein folding.

Plasma hyaluronan, hyaluronidase activity and endogenous hyaluronidase inhibition in sepsis: an experimental and clinical cohort study

Background

Plasma hyaluronan concentrations are increased during sepsis but underlying mechanisms leading to high plasma hyaluronan concentration are poorly understood. In this study we evaluate the roles of plasma hyaluronan, effective plasma hyaluronidase (HYAL) activity and its endogenous plasma inhibition in clinical and experimental sepsis. We specifically hypothesized that plasma HYAL acts as endothelial glycocalyx shedding enzyme, sheddase.

Methods

Plasma hyaluronan, effective HYAL activity and HYAL inhibition were measured in healthy volunteers (n = 20), in patients with septic shock (n = 17, day 1 and day 4), in patients with acute pancreatitis (n = 7, day 1 and day 4) and in anesthetized and mechanically ventilated pigs (n = 16). Sixteen pigs were allocated (unblinded, open label) into three groups: Sepsis-1 with infusion of live Escherichia coli (E. coli) 1 × 10⁸ CFU/h of 12 h (n = 5), Sepsis-2 with infusion of E. coli 1 × 10⁸ CFU/h of 6 h followed by 1 × 10⁹ CFU/h of the remaining 6 h (n = 5) or Control with no E. coli infusion (n = 6).

Results

In experimental E. coli porcine sepsis and in time controls, plasma hyaluronan increases with concomitant decrease in effective plasma HYAL activity and increase of endogenous HYAL inhibition. Plasma hyaluronan increased in patients with septic shock but not in acute pancreatitis. Effective plasma HYAL was lower in septic shock and acute pancreatitis as compared to healthy volunteers, while plasma HYAL inhibition was only increased in septic shock.

Conclusion

Elevated plasma hyaluronan levels coincided with a concomitant decrease in effective plasma HYAL activity and increase of endogenous plasma HYAL inhibition both in experimental and clinical sepsis. In acute pancreatitis, effective plasma HYAL activity was decreased which was not associated with increased plasma hyaluronan concentrations or endogenous HYAL inhibition. The results suggest that plasma HYAL does not act as sheddase in sepsis or pancreatitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-021-00418-3.

Nanoencapsulation of Hirudo medicinalis proteins in liposomes as a nanocarrier for inhibiting angiogenesis through targeting VEGFA in the Breast cancer cell line (MCF-7)

Introduction: Breast cancer is the most serious cause of women’s death throughout the world. Using nanocarrier vehicles to the exact site of cancer upgrades the therapeutic efficiency of the drugs. Capsulation of active proteins in the vesicular liposomes’ hydrophilic core is essential to develop a therapeutic protein carrier system. We aimed to encapsulate the medicinal leech saliva extract (LSE) and assess the inhibition of angiogenesis of breast cancer cells by targeting vascular endothelial growth factor A (VEGFA). Methods: In this research, enhanced formulation of liposomal protein was determined by zeta potential analysis, droplet size, drug release assay, and transmission electron microscopy (TEM). Furthermore, a cytotoxicity assay of liposomal LSE was performed to determine the cytotoxic activity of components. For assessing the expression of VEGFA, P53, and hypoxia-inducible factor subunit alpha (HIF1a) genes, Real-Time PCR was applied. Results: Nano liposome was chosen as an enhanced formulation due to its much smaller size (46.23 nm). Liposomal LSE had more practical actions on the MCF-7 cells. As noticed by DAPI staining, apoptosis was extensively greater in treated MCF-7 cells. Wound healing assay demonstrated that MCF-7 cells could not sustain growth at the presence of liposomal LSE and expression of the VEGFA gene was declined in treated cells. Downregulation of VEGFA was evaluated with western blotting technique. Conclusion: It can be concluded that our investigation of the tests confirmed the fact that nano liposomal LSE is a novel promising formulation for anticancer drugs and can significantly improve the penetration of protein drugs to cancer cells.

Autocrine Hyaluronan Influences Sprouting and Lumen Formation During HUVEC Tubulogenesis In Vitro

Although many studies have focused on a role for hyaluronan (HA) of interstitial extracellular matrix (presumably produced by non-vascular "stromal" cells) in regulating vascular growth, we herein examine the influence of "autocrine HA" produced by vascular endothelial cells themselves on tubulogenesis, using human umbilical vein endothelial cells (HUVECs) in angiogenic and vasculogenic three-dimensional collagen gel cultures. Relative to unstimulated controls, tubulogenic HUVECs upregulated HAS2 mRNA and increased the synthesis of cell-associated HA (but not HA secreted into media). Confocal microscopy/immunofluorescence on cultures fixed with neutral-buffered 10% formalin (NBF) revealed cytoplasmic HAS2 in HUVEC cords and tubes. Cultures fixed with NBF (with cetylpyridinium chloride added to retain HA), stained for HA using "affinity fluorescence" (biotinylated HA-binding protein with streptavidin-fluor), and viewed by confocal microscopy showed HA throughout tube lumens, but little/no HA on the abluminal sides of the tubes or in the surrounding collagen gel. Lumen formation in angiogenic and vasculogenic cultures was strongly suppressed by metabolic inhibitors of HA synthesis (mannose and 4-methylumbelliferone). Hyaluronidase strongly inhibited lumen formation in angiogenic cultures, but not in vasculogenic cultures (where developing lumens are not open to culture medium). Collectively, our results point to a role for autocrine, luminal HA in microvascular sprouting and lumen development. (J Histochem Cytochem 69: 415-428, 2021).

Bromamine T, a stable active bromine compound, prevents the LPS‑induced inflammatory response

Inflammation is the most common cause of most acute and chronic debilitating diseases. Towards unveiling novel therapeutic options for patients with such complications, N‑bromotaurine (TauNHBr) has emerged as a potential anti‑inflammatory agent; however, its therapeutic efficacy is hindered due to its relatively poor stability. To address this challenge, the present study focused on examining the effects of a stable active bromine compound, named bromamine T (BAT). The present study examined the protective properties of BAT against lipopolysaccharide (LPS)‑mediated inflammation in vitro, by using LPS‑stimulated murine J774.A1 macrophages (Mφs), as well as in vivo, by using a murine LPS‑mediated air‑pouch model. Additionally, its efficacy was compared with that of taurine, a known potent anti‑inflammatory molecule. In LPS‑stimulated J774A.1 Mφs, BAT and taurine were very effective in reducing the secretion of pro‑inflammatory mediators. The in vitro experiments indicated that LPS‑mediated inflammation was attenuated due to the protective properties of BAT and of taurine, probably through the inhibition of phosphorylated p65 NF‑κB subunit (Ser 536) nuclear translocation. The in vivo experiments also revealed that BAT and taurine inhibited LPS‑mediated inflammation by reducing total cell/polymorphonuclear cell (PMN) infiltration in the air‑pouch and by decreasing pouch wall thickness. The analysis of exudates obtained from pouches highlighted that the inhibitory effects of BAT and taurine on the secretion of pro‑inflammatory cytokines were similar to those observed in vitro. Notably, the effect of BAT at the highest concentration tested was superior to that of taurine at the highest concentration. Taken together, the findings of the present study indicate that BAT prevents the LPS‑induced inflammatory response both in vitro and in vivo.

Hyaluronan oligosaccharides modulate inflammatory response, NIS and thyreoglobulin expression in human thyrocytes

Autoimmune thyroid diseases, such as Hashimoto's thyroiditis, are characterized by lymphocytic infiltration and altered function of the thyroid. During inflammation, it has been reported a decreased expression in Tg and NIS, accompanied by an increase in HA production that accumulates in the gland. HA fragments produced in different pathological states can modulate gene expression in a variety of cell types and may prime inflammatory response by interacting with the TLR-2, TLR-4 and CD44 that, in turn, induce NF-kB activation finally responsible of inflammatory mediator transcription, such as IL-1β, TNF-α and IL-6. The aim of this study was to investigate the potential inflammatory effect and the biochemical pathways activated by 6-mer HA oligosaccharides in cultured human thyrocytes. 6-mer HA treatment induced up-regulation of TLR-2, TLR-4, CD44 mRNA and related protein levels, increased HA production and NF-kB activation, that in turn increased IL-1β and IL-6 concentrations. Instead, we found evidence of an opposite effect on thyroid specific-gene Tg and NIS, that were decreased after 6-mer HA addition. Thyrocytes exposition to specific blocking antibodies for TLR-2, TLR-4 and CD44 abolished up-regulation of NF-κB activation and the consequent pro-inflammatory cytokine production, while restored Tg and NIS levels. A further goal of this study was demonstrate that also other LMW HA have pro inflammatory proprieties. These data suggest that HA fragments, through the involvement of TLR-2, TLR-4 and CD44 signaling cascade, contribute to prime the inflammatory response in thyrocytes and, by reducing the expression of thyroid-specific genes, could promote the loss of function of gland such as in Hashimoto's thyroiditis.

Role of Hyaluronan in Inflammatory Effects on Human Articular Chondrocytes

Hyaluronan (HA) fragments have been proposed to elicit defensive or pro-inflammatory responses in many cell types. For articular chondrocytes in an inflammatory environment, studies have failed to reach consensus on the endogenous production or effects of added HA fragments. The present study was undertaken to resolve this discrepancy. Cultured primary human articular chondrocytes were exposed to the inflammatory cytokine IL-1β, and then tested for changes in HA content/size in conditioned medium, and for the expression of genes important in HA binding/signaling or metabolism, and in other catabolic/anabolic responses. Changes in gene expression caused by enzymatic degradation of endogenous HA, or addition of exogenous HA fragments, were examined. IL-1β increased the mRNA levels for HA synthases HAS2/HAS3 and for the HA-binding proteins CD44 and TSG-6. mRNA levels for TLR4 and RHAMM were very low and were little affected by IL-1β. mRNA levels for catabolic markers were increased, while type II collagen (α1(II)) and aggrecan were decreased. HA concentration in the conditioned medium was increased, but the HA was not degraded. Treatment with recombinant hyaluronidase or addition of low endotoxin HA fragments did not elicit pro-inflammatory responses. Our findings showed that HA fragments were not produced by IL-1β-stimulated human articular chondrocytes in the absence of other sources of reactive oxygen or nitrogen species, and that exogenous HA fragments from oligosaccharides up to about 40 kDa in molecular mass were not pro-inflammatory agents for human articular chondrocytes, probably due to low expression of TLR4 and RHAMM in these cells.

In-Vivo Efficacy of Recombinant Human Hyaluronidase (rHuPH20) Injection for Accelerated Healing of Murine Retrocalcaneal Bursitis and Tendinopathy

The deposition of aggrecan/hyaluronan (HA)-rich matrix within the tendon body and surrounding peritenon impede tendon healing and result in compromised biomechanical properties. Hence, the development of novel strategies to achieve targeted removal of the aggrecan-HA pericellular matrix may be effective in treating tendinopathy. The current study examined the therapeutic potential of a recombinant human hyaluronidase, rHuPH20 (FDA approved for reducing HA accumulation in tumors) for treating murine Achilles tendinopathy. The 12-week-old C57Bl/6 male mice were injected with two doses of rHuTGF-β1 into the retrocalcaneal bursa (RCB) to induce a combined bursitis and tendinopathy. Twenty-four hours following induction of injury, treatment groups were administered rHuPH20 Hyaluronidase (rHuPH20; Halozyme Therapeutics) into the RCB. At either 6 h (acute), 9 days, or 25 days following hyaluronidase treatment, Achilles tendons were analyzed for gene expression, histology and immunohistochemistry, fluorophore-assisted carbohydrate electrophoresis, and biomechanical properties. The rHuPH20 treatment was effective, particularly at the acute and 9-day time points, in (a) removing HA deposits from the Achilles tendon and surrounding tissues, (b) improving biomechanical properties of the healing tendon, and (c) eliciting targeted increases in expression of specific cell fate, extracellular matrix metabolism, and inflammatory genes. The potential of rHuPH20 to effectively clear the pro-inflammatory, HA-rich matrix within the RCB and tendon strongly supports the future refinement of injectable glycosidase preparations as potential treatments to protect or regenerate tendon tissue by reducing inflammation and scarring in the presence of bursitis or other inducers of damage such as mechanical overuse. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:59-69, 2020.

Purification of hyaluronidase as an anticancer agent inhibiting CD44

Hyaluronidase (Hyal) can be employed to accomplish a diversity of complications related to hyaluronic acid (HA). Hyal contains some classes of catalysts that cleave HA. This enzyme is detected in several human tissues as well as in animal venoms, pathogenic organisms and cancers. Destructive cancer cells regularly increase the CD44 receptor existing in a cell membrane. This receptor acts as an exact receptor for HA, and HA is recognized to motivate the migration, spread, attack and metastasis of cancer cells. Nearly all of the methods used to purify Hyal are highly costly and not proper for industrial applications. This survey aims to review different methods of Hyal purification, which acts as an anticancer agent by degrading HA in tissues and thus inhibiting the CD44-HA interaction. Hyal can be successfully employed in the management of cancer, which is associated with HA-CD44. This review has described different methods for Hyal purification to prepare an origin to develop a novel purification technique for this highly appreciated protein. Using multiple columns is not applicable for the purification of Hyal and thus cannot be used at the industrial level. It is better to use affinity chromatography of anti-Hyal for Hyal with one-step purification.

Crocin inhibits titanium particle-induced inflammation and promotes osteogenesis by regulating macrophage polarization

Wear particle-induced periprosthetic inflammatory osteolysis and resultant aseptic loosening are major causes of orthopedic implant failure, for which there are no effective treatments other than revision surgery. Crocin, a carotenoid compound derived from crocus flowers, has anti-inflammatory properties, but its immunomodulatory function and role in particle-induced osteolysis are not well characterized. Here we report the effect of crocin on titanium (Ti) particle-induced macrophage polarization and osteogenic differentiation. We found that crocin induced anti-inflammatory (M2) macrophage polarization and attenuated Ti particle-induced inflammation by promoting the expression of anti-inflammatory cytokines in vitro as well as in vivo in a mouse air-pouch model. Additionally, crocin pre-treated macrophages promoted osteogenic differentiation of co-cultured mouse bone mesenchymal stem cells (BMSCs). These effects were mediated via inhibition of p38 and c-Jun N-terminal kinase signaling. Our results indicate that crocin suppresses Ti particle-induced inflammation and enhances osteogenic differentiation of BMSCs by inducing M2 macrophage polarization, highlighting its therapeutic potential for preventing wear particle-induced osteolysis.

Platelet hyaluronidase-2 regulates the early stages of inflammatory disease in colitis

Platelets are specialized cells essential for hemostasis that also function as crucial effectors capable of mediating inflammatory and immune responses. These sentinels continually survey their environment and discriminate between homeostatic and danger signals such as modified components of the extracellular matrix. The glycosaminoglycan hyaluronan (HA) is a major extracellular matrix component that coats the vascular lumen and, under normal conditions, restricts access of inflammatory cells. In response to tissue damage, the endothelial HA matrix enhances leukocyte recruitment and regulates the early stages of the inflammatory response. We have shown that platelets can degrade HA from the surface of activated endothelial cells via the enzyme hyaluronidase-2 (HYAL2) and that HYAL2 is deficient in platelets isolated from patients with inflammatory bowel disease (IBD). Platelets are known to be involved in the pathogenesis of several chronic disease states, including IBD, but they have been largely overlooked in the context of intestinal inflammation. We therefore wanted to define the mechanism by which platelet HYAL2 regulates the inflammatory response during colitis. In this study, we provide evidence that HA catabolism is disrupted in human intestinal microvascular endothelial cells isolated from patients with IBD. Furthermore, mice deficient in HYAL2 are more susceptible to an acute model of colitis, and this increased susceptibility is abrogated by transfusion of HYAL2-competent platelets. Finally, we show that platelets, via HYAL2-dependent degradation of endothelial HA, regulate the early stages of inflammation in colitis by limiting leukocyte extravasation.

Hyaluronan and Its Interactions With Immune Cells in the Healthy and Inflamed Lung

Hyaluronan is a hygroscopic glycosaminoglycan that contributes to both extracellular and pericellular matrices. While the production of hyaluronan is essential for mammalian development, less is known about its interaction and function with immune cells. Here we review what is known about hyaluronan in the lung and how it impacts immune cells, both at homeostasis and during lung inflammation and fibrosis. In the healthy lung, alveolar macrophages provide the first line of defense and play important roles in immunosurveillance and lipid surfactant homeostasis. Alveolar macrophages are surrounded by a coat of hyaluronan that is bound by CD44, a major hyaluronan receptor on immune cells, and this interaction contributes to their survival and the maintenance of normal alveolar macrophage numbers. Alveolar macrophages are conditioned by the alveolar environment to be immunosuppressive, and can phagocytose particulates without alerting an immune response. However, during acute lung infection or injury, an inflammatory immune response is triggered. Hyaluronan levels in the lung are rapidly increased and peak with maximum leukocyte infiltration, suggesting a role for hyaluronan in facilitating leukocyte access to the injury site. Hyaluronan can also be bound by hyaladherins (hyaluronan binding proteins), which create a provisional matrix to facilitate tissue repair. During the subsequent remodeling process hyaluronan concentrations decline and levels return to baseline as homeostasis is restored. In chronic lung diseases, the inflammatory and/or repair phases persist, leading to sustained high levels of hyaluronan, accumulation of associated immune cells and an inability to resolve the inflammatory response.

In Vivo Evaluation of a New Recombinant Hyaluronidase to Improve Gene Electro-Transfer Protocols for DNA-Based Drug Delivery against Cancer

Cancer vaccines based on plasmid DNA represent a good therapeutic perspective, despite their low potency. Animal-derived hyaluronidases (Hyals) are employed in oncological clinical practice. Hyal has been also demonstrated to be a good enhancer of intramuscular Gene Electro-Transfer (GET) efficiency in anti-cancer preclinical protocols, with increased transfected cells and higher expression of the encoded genes. Nevertheless, the use of animal-derived Hyals results limited respect to their potentialities, since such preparations could be affected by low purity, variable potency and uncertain safety. To improve the delivery of intramuscular GET-based protocols in mouse, we investigated a new recombinant Hyal, the rHyal-sk, to assess in vivo safety and activity of this treatment at cellular and biochemical levels. We evaluated the cellular events and the inflammation chemical mediators involved at different time points after rHyal-sk administration plus GET. Our results demonstrated the in vivo safety and efficacy of rHyal-sk when injected once intramuscularly in association with GET, with no toxicity, good plasmid in-take ability, useful inflammatory response activation, and low immunogenicity. Following these findings, we would recommend the use of the new rHyal-sk for the delivery of DNA-based vaccines and immunotherapy, as well as into clinical practice, for tumor disease treatments.

The pericellular hyaluronan of articular chondrocytes

The story of hyaluronan in articular cartilage, pericellular hyaluronan in particular, essentially is also the story of aggrecan. Without properly tethered aggrecan, the load bearing function of cartilage is compromised. The anchorage of aggrecan to the cell surface only occurs due to the binding of aggrecan to hyaluronan-with hyaluronan tethered either to a hyaluronan synthase or by multivalent binding to CD44. In this review, details of hyaluronan synthesis are discussed including how HAS2 production of hyaluronan is necessary for normal chondrocyte development and matrix assembly, how an abundance or deficit of pericellular hyaluronan alters chondrocyte metabolism, and whether hyaluronan size matters or changes with aging or disease. The biomechanical role and matrix assembly function of hyaluronan in addition to the functions of hyaluronidases are discussed. The turnover of hyaluronan is considered including mechanisms by which its turnover, at least in part, is mediated by endocytosis by chondrocytes and regulated by aggrecan degradation. Differences between turnover and clearance of newly synthesized hyaluronan and aggrecan versus the half-life of hyaluronan remaining within the inter-territorial matrix of cartilage are discussed. The release of neutral pH-acting hyaluronidase activity remains one unanswered question concerning the loss of cartilage hyaluronan in osteoarthritis. Signaling events driven by changes in hyaluronan-chondrocyte interactions may involve a chaperone function of CD44 with other receptors/cofactors as well as the changes in hyaluronan production functioning as a metabolic rheostat.

Design of peptide mimetics to block pro-inflammatory functions of HA fragments

Hyaluronan is a simple extracellular matrix polysaccharide that actively regulates inflammation in tissue repair and disease processes. The native HA polymer, which is large (>500 kDa), contributes to the maintenance of homeostasis. In remodeling and diseased tissues, polymer size is strikingly polydisperse, ranging from <10 kDa to >500 kDa. In a diseased or stressed tissue context, both smaller HA fragments and high molecular weight HA polymers can acquire pro-inflammatory functions, which result in the activation of multiple receptors, triggering pro-inflammatory signaling to diverse stimuli. Peptide mimics that bind and scavenge HA fragments have been developed, which show efficacy in animal models of inflammation. These studies indicate both that HA fragments are key to driving inflammation and that scavenging these is a viable therapeutic approach to blunting inflammation in disease processes. This mini-review summarizes the peptide-based methods that have been reported to date for blocking HA signaling events as an anti-inflammatory therapeutic approach.

Hyaluronan and Hyaluronan Fragments

The glycosaminoglycan hyaluronan (HA) is a key component of the microenvironment surrounding cells. In healthy tissues, HA molecules have extremely high molecular mass and consequently large hydrodynamic volumes. Tethered to the cell surface by clustered receptor proteins, HA molecules crowd each other, as well as other macromolecular species. This leads to severe nonideality in physical properties of the biomatrix, because steric exclusion leads to an increase in effective concentration of the macromolecules. The excluded volume depends on both polymer concentration and hydrodynamic volume/molecular mass. The biomechanical properties of the extracellular matrix, tissue hydration, receptor clustering, and receptor-ligand interactions are strongly affected by the presence of HA and by its molecular mass. In inflammation, reactive oxygen and nitrogen species fragment the HA chains. Depending on the rate of chain degradation relative to the rates of new synthesis and removal of damaged chains, short fragments of the HA molecules can be present at significant levels. Not only are the physical properties of the extracellular matrix affected, but the HA fragments decluster their primary receptors and act as endogenous danger signals. Bioanalytical methods to isolate and quantify HA fragments have been developed to determine profiles of HA content and size in healthy and diseased biological fluids and tissues. These methods have potential use in medical diagnostic tests. Therapeutic agents that modulate signaling by HA fragments show promise in wound healing and tissue repair without fibrosis.

Planning, evaluating and vetting receptor signaling studies to assess hyaluronan size-dependence and specificity

Exciting discoveries in many diverse fields of hyaluronan (HA) biology over the last 40 years have centered around the ability of HA to bind cell surface HA receptors (e.g., CD44, Layilin, LYVE-1, HARE/Stab2 and RHAMM) and sometimes also to activate intracellular signal transduction pathways, frequently involving ERK1/2. Although perplexing, a major characteristic of HA-mediated signal pathway activation for some receptors has been a dependence on the size of the bound HA. Receptors that directly interact with HA, which may not include TLR2/4, bind very well to any HA molecule >8-20 sugars, depending on the receptor. Despite their ability to bind virtually any size HA, only HA chains of a particular mass range can activate receptor-mediated cell signaling. Many studies have demonstrated parts of this emerging story by utilizing different: HA receptors, cell types, animal models, HA sources, HA sizes, assays to assess HA mass and varying controls to verify HA specificity or HA size-dependence. Recent reports have highlighted issues with potential endotoxin contamination of HA fragments, especially those generated by hyaluronidase digestion. Also, researchers unfamiliar with HA polydispersity must adjust to working with, and interpreting data for, preparations without a unique molecular mass (molecular weight). The confusion, uncertainty and skepticism generated by these and other factors has hindered the development of a general consensus about HA-specific and HA-size dependent receptor activation. An overview of issues, suggested strategies and validating controls is presented to aid those planning an HA-mediated receptor signaling study or those trying to evaluate the literature.

What is special about 200 kDa hyaluronan that activates hyaluronan receptor signaling?

The polydispersity of hyaluronan (HA) presents challenges for analyzing its solution properties, such as the relationship between mass and particle size. The broad mass range of natural HA (≤50-fold) makes molecular characterization difficult and ambiguous compared to molecules with known molecular weights (e.g., proteins). Biophysical studies show that large >MDa HA behaves like a random coil, whereas very small (e.g., 10 kDa) HA behaves like a rod. However, the mass range for this conformational transition is not easily determined in natural polydisperse HA. Some HA receptors (e.g., CD44 and HARE) initiate signaling responses upon binding HA in the 100-300 kDa range, but not larger MDa HA. Size-dependent responses are studied using nonnatural HA: purified narrow-size range HA [Pandey MS, Baggenstoss BA, Washburn J, Harris EN, Weigel PH. 2013. The hyaluronan receptor for endocytosis (HARE) activates NF-κB-mediated gene expression in response to 40-400 kDa, but not smaller or sarger, hyaluronans. J Biol Chem. 288:14068-14079] and very narrow size range Select-HA made chemo-enzymatically [Jing W, DeAngelis PL. 2004. Synchronized chemoenzymatic synthesis of monodisperse hyaluronan polymers. J Biol Chem. 279:42345-42349]. Here, we used size exclusion chromatography and multiangle light scattering to determine the weight-average molar mass and diameter of ~60 very narrow size preparations from 29 to 1650 kDa. The ratio of HA mass to HA diameter showed a transition in the 150-250 kDa size range (~65 nm). The HA rod-to-coil transition occurs within the size range that specifically activates cell signaling by some receptors. Thus, size-specific signaling could be due to unique external receptor•HA conformation changes that enable transmembrane-mediated activation of cytoplasmic domains. Alternatively and more likely, transition-size HA may enable multiple receptors to bind the same HA, creating new internal signal-competent cytoplasmic domain complexes.

Absence of differences among low, middle, and high molecular weight hyaluronan in activating murine immune cells in vitro

Hyaluronan (HA) effects on immune response are suggested to be dependent on HA molecular weight (MW), as low MW HA should activate immune cells in contrast to high MW HA. However, some current studies do not support this conception and emphasize the importance of the form of preparation of HA, particularly with respect to its purity and origin. We compared the activation of mouse immune cells by HA samples (100kDa, 500kDa, and 997kDa) prepared from HA originating from rooster comb, and HA samples (71kDa, 500kDa, and 1000kDa) prepared from pharmacological grade HA originating from Streptococcus equi. Interestingly, in contrast to established theory, only middle and high MW HA originating from rooster comb induced the production of tumor necrosis factor-α by macrophages and in whole blood. Further, all tested preparations of HA failed to induce the expression of inducible nitric oxide synthase, the production of nitric oxide, or the expression of cyclooxygenase 2 in macrophages and splenocytes. Importantly, all HA samples originating from rooster comb were found to be contaminated by endotoxin (up to 1.23EU/ml). Hence, low MW HA did not reveal itself to have significantly higher immunostimulatory activity compared to HA of higher MW.

Inflammation-a Critical Appreciation of the Role of Myeloid Cells

What is inflammation's big idea? In this brief overview of the role of myeloid cells in inflammation, we will critically discuss what drives the initiation, amplification, and resolution of inflammation in different anatomical sites in response to different pathological stimuli. It can be argued that we have a good understanding of the basic principles that underlie myeloid cell activation and the mobilization of innate immune cells to sites of injury and infection in acute inflammation. The challenge now for inflammation biologists is to understand how resolution of this normal physiological response goes wrong in hyperacute and chronic inflammation. A better understanding of how inflammation is regulated will allow us to develop new anti-inflammatory drugs that will reduce the burden of inflammatory disease without compromising the patient's immune defenses against infectious disease. Ideally such drugs should encourage a return to homeostasis and enhance tissue repair processes.

Low molecular weight hyaluronan induces migration of human choriocarcinoma JEG-3 cells mediated by RHAMM as well as by PI3K and MAPK pathways

Hyaluronan (HA) is the major glycosaminoglycan present in the extracellular matrix. It is produced by some tumours and promotes proliferation, differentiation and migration among others cellular processes. Gestational trophoblastic disease (GTD) is composed by non-tumour entities, such as hydatidiform mole (HM), which is the most common type of GTD and also malignant entities such as choriocarcinoma (CC) and placental site trophoblastic tumour (PSTT), being CC the most aggressive tumour. Although there is a growing understanding of GTD biology, the role of HA in the pathogenesis of this group of diseases remains largely unknown. The aim of this work was to study the role of HA in the pathogenesis of GTD by defining the expression pattern of HA and its receptors CD44 and RHAMM, as well as to determine if HA can modulate proliferation, differentiation and migration of CC cells. Receptors and signalling pathways involved were also analyzed. We demonstrated that HA and RHAMM are differently expressed among GTD entities and even among trophoblast subtypes. We also showed that HA is able to enhance the expression of extravillous trophoblast markers and also to induce migration of JEG-3 cells, the latter mediated by RHAMM as well as PI3K and MAPK pathways. These findings indicate a novel regulatory mechanism for CC cell biology and also contribute to the understanding of GTD pathophysiology.

PH20 is not expressed in murine CNS and oligodendrocyte precursor cells

Objective

Expression of Spam1/PH20 and its modulation of high/low molecular weight hyaluronan substrate have been proposed to play an important role in murine oligodendrocyte precursor cell (OPC) maturation in vitro and in normal and demyelinated central nervous system (CNS). We reexamined this using highly purified PH20.

Methods

Steady‐state expression of mRNA in OPCs was evaluated by quantitative polymerase chain reaction; the role of PH20 in bovine testicular hyaluronidase (BTH) inhibition of OPC differentiation was explored by comparing BTH to a purified recombinant human PH20 (rHuPH20). Contaminants in commercial BTH were identified and their impact on OPC differentiation characterized. Spam1/PH20 expression in normal and demyelinated mouse CNS tissue was investigated using deep RNA sequencing and immunohistological methods with two antibodies directed against recombinant murine PH20.

Results

BTH, but not rHuPH20, inhibited OPC differentiation in vitro. Basic fibroblast growth factor (bFGF) was identified as a significant contaminant in BTH, and bFGF immunodepletion reversed the inhibitory effects of BTH on OPC differentiation. Spam1 mRNA was undetected in OPCs in vitro and in vivo; PH20 immunolabeling was undetected in normal and demyelinated CNS.

Interpretation

We were unable to detect Spam1/PH20 expression in OPCs or in normal or demyelinated CNS using the most sensitive methods currently available. Further, “BTH” effects on OPC differentiation are not due to PH20, but may be attributable to contaminating bFGF. Our data suggest that caution be exercised when using some commercially available hyaluronidases, and reports of Spam1/PH20 morphogenic activity in the CNS may be due to contaminants in reagents.

Endotoxin free hyaluronan and hyaluronan fragments do not stimulate TNF-α, interleukin-12 or upregulate co-stimulatory molecules in dendritic cells or macrophages

The extracellular matrix glycosaminoglycan, hyaluronan, has been described as a regulator of tissue inflammation, with hyaluronan fragments reported to stimulate innate immune cells. High molecular mass hyaluronan is normally present in tissues, but upon inflammation lower molecular mass fragments are generated. It is unclear if these hyaluronan fragments induce an inflammatory response or are a consequence of inflammation. In this study, mouse bone marrow derived macrophages and dendritic cells (DCs) were stimulated with various sizes of hyaluronan from different sources, fragmented hyaluronan, hyaluronidases and heavy chain modified-hyaluronan (HA-HC). Key pro-inflammatory molecules, tumour necrosis factor alpha, interleukin-1 beta, interleukin-12, CCL3, and the co-stimulatory molecules, CD40 and CD86 were measured. Only human umbilical cord hyaluronan, bovine testes and Streptomyces hyaluronlyticus hyaluronidase stimulated macrophages and DCs, however, these reagents were found to be contaminated with endotoxin, which was not fully removed by polymyxin B treatment. In contrast, pharmaceutical grade hyaluronan and hyaluronan fragments failed to stimulate in vitro-derived or ex vivo macrophages and DCs, and did not induce leukocyte recruitment after intratracheal instillation into mouse lungs. Hence, endotoxin-free pharmaceutical grade hyaluronan does not stimulate macrophages and DCs in our inflammatory models. These results emphasize the importance of ensuring hyaluronan preparations are endotoxin free.

Hyaluronidase activity in the salivary glands of tabanid flies

Tabanids are haematophagous insects that act as biological and mechanical vectors of various diseases, including viruses, bacteria and parasites. The saliva of these insects contains strong anticoagulant and vasodilatory activities as well as immunoregulatory peptides. Here we demonstrate pronounced hyaluronidase (hyase) activity in ten tabanid species of the genera Chrysops, Haematopota, Hybomitra and Tabanus. Compared to other haematophagous insects, the ability of tabanid hyases to hydrolyze hyaluronic acid (HA) is extremely high, for example the enzyme activity of Hybomitra muehlfeldi was found to be 32-fold higher than the salivary hyase activity of the sand fly Phlebotomus papatasi. Hyases of all ten tabanid species tested also cleaved chondroitin sulfate A, another glycosaminoglycan present in the extracellular matrix of vertebrates. The pH optimum of the enzyme activity was measured in eight tabanid species; the hyase of Haemopota pluvialis was the only one with optimum at pH 4.0, while in the other seven species the activity optimum was at 5.0. SDS PAGE zymography showed the monomeric character of the enzymes in all tabanid species tested. Under non-reducing conditions the activities were visible as single bands with estimated MW between 35 and 52 kDa. The very high hyaluronidase activity in tabanid saliva might be related to their aggressive biting behavior as well as to their high efficiency as mechanical vectors. As they are supposedly involved in the enlargement of feeding hematomas, hyases might contribute to the mechanical transmission of pathogens. Pathogens present in vector mouthparts are co-inoculated into the vertebrate host together with saliva and may benefit from increased tissue permeability and the immunomodulatory activity of the salivary hyase.

Hyaluronidase and Hyaluronan Oligosaccharides Promote Neurological Recovery after Intraventricular Hemorrhage

Intraventricular hemorrhage (IVH) in premature infants results in inflammation, arrested oligodendrocyte progenitor cell (OPC) maturation, and reduced myelination of the white matter. Hyaluronan (HA) inhibits OPC maturation and complexes with the heavy chain (HC) of glycoprotein inter-α-inhibitor to form pathological HA (HC-HA complex), which exacerbates inflammation. Therefore, we hypothesized that IVH would result in accumulation of HA, and that either degradation of HA by hyaluronidase treatment or elimination of HCs from pathological HA by HA oligosaccharide administration would restore OPC maturation, myelination, and neurological function in survivors with IVH. To test these hypotheses, we used the preterm rabbit model of glycerol-induced IVH and analyzed autopsy samples from premature infants. We found that total HA levels were comparable in both preterm rabbit pups and human infants with and without IVH, but HA receptors--CD44, TLR2, TLR4--were elevated in the forebrain of both humans and rabbits with IVH. Hyaluronidase treatment of rabbits with IVH reduced CD44 and TLR4 expression, proinflammatory cytokine levels, and microglia infiltration. It also promoted OPC maturation, myelination, and neurological recovery. HC-HA and tumor necrosis factor-stimulated gene-6 were elevated in newborns with IVH; and depletion of HC-HA levels by HA oligosaccharide treatment reduced inflammation and enhanced myelination and neurological recovery in rabbits with IVH. Hence, hyaluronidase or HA oligosaccharide treatment represses inflammation, promotes OPC maturation, and restores myelination and neurological function in rabbits with IVH. These therapeutic strategies might improve the neurological outcome of premature infants with IVH. Significance statement: Approximately 12,000 premature infants develop IVH every year in the United States, and a large number of survivors with IVH develop cerebral palsy and cognitive deficits. The onset of IVH induces inflammation of the periventricular white matter, which results in arrested maturation of OPCs and myelination failure. HA is a major component of the extracellular matrix of the brain, which regulates inflammation through CD44 and TLR2/4 receptors. Here, we show two mechanism-based strategies that effectively enhanced myelination and neurological recovery in preterm rabbit model of IVH. First, degrading HA by hyaluronidase treatment reduced CD44 and TLR4 expression, proinflammatory cytokines, and microglial infiltration, as well as promoted oligodendrocyte maturation and myelination. Second, intraventricular injection of HA oligosaccharide reduced inflammation and enhanced myelination, conceivably by depleting HC-HA levels.

Hyaluronidase Activity in Saliva of European Culicoides (Diptera: Ceratopogonidae)

Biting midges of the genus Culicoides transmit pathogens of veterinary importance such as bluetongue virus (Reoviridae: Orbivirus). The saliva of Culicoides is known to contain bioactive molecules including peptides and proteins with vasodilatory and immunomodulative properties. In this study, we detected activity of enzyme hyaluronidase in six Culicoides species that commonly occur in Europe and that are putative vectors of arboviruses. Hyaluronidase was present in all species studied, although its molecular size, sensitivity to SDS, and substrate specificity differed between species. Further studies on the potential effect of hyaluronidase activity on the vector competence of Culicoides species for arboviruses would be beneficial.

Viscoelastic Properties of Hyaluronan in Physiological Conditions

Hyaluronan (HA) is a high molecular weight glycosaminoglycan of the extracellular matrix (ECM), which is particularly abundant in soft connective tissues. Solutions of HA can be highly viscous with non-Newtonian flow properties. These properties affect the movement of HA-containing fluid layers within and underlying the deep fascia. Changes in the concentration, molecular weight, or even covalent modification of HA in inflammatory conditions, as well as changes in binding interactions with other macromolecules, can have dramatic effects on the sliding movement of fascia. The high molecular weight and the semi-flexible chain of HA are key factors leading to the high viscosity of dilute solutions, and real HA solutions show additional nonideality and greatly increased viscosity due to mutual macromolecular crowding. The shear rate dependence of the viscosity, and the viscoelasticity of HA solutions, depend on the relaxation time of the molecule, which in turn depends on the HA concentration and molecular weight. Temperature can also have an effect on these properties. High viscosity can additionally affect the lubricating function of HA solutions. Immobility can increase the concentration of HA, increase the viscosity, and reduce lubrication and gliding of the layers of connective tissue and muscle. Over time, these changes can alter both muscle structure and function. Inflammation can further increase the viscosity of HA-containing fluids if the HA is modified via covalent attachment of heavy chains derived from Inter-α-Inhibitor. Hyaluronidase hydrolyzes HA, thus reducing its molecular weight, lowering the viscosity of the extracellular matrix fluid and making outflow easier. It can also disrupt any aggregates or gel-like structures that result from HA being modified. Hyaluronidase is used medically primarily as a dispersion agent, but may also be useful in conditions where altered viscosity of the fascia is desired, such as in the treatment of muscle stiffness.

Interleukin-1β-induced Reduction of CD44 Ser-325 Phosphorylation in Human Epidermal Keratinocytes Promotes CD44 Homomeric Complexes, Binding to Ezrin, and Extended, Monocyte-adhesive Hyaluronan Coats

The proinflammatory cytokine interleukin-1β (IL-1β) attracts leukocytes to sites of inflammation. One of the recruitment mechanisms involves the formation of extended, hyaluronan-rich pericellular coats on local fibroblasts, endothelial cells, and epithelial cells. In the present work, we studied how IL-1β turns on the monocyte adhesion of the hyaluronan coat on human keratinocytes. IL-1β did not influence hyaluronan synthesis or increase the amount of pericellular hyaluronan in these cells. Instead, we found that the increase in the hyaluronan-dependent monocyte binding was associated with the CD44 of the keratinocytes. Although IL-1β caused a small increase in the total amount of CD44, a more marked impact was the decrease of CD44 phosphorylation at serine 325. At the same time, IL-1β increased the association of CD44 with ezrin and complex formation of CD44 with itself. Treatment of keratinocyte cultures with KN93, an inhibitor of calmodulin kinase 2, known to phosphorylate Ser-325 in CD44, caused similar effects as IL-1β (i.e. homomerization of CD44 and its association with ezrin) and resulted in increased monocyte binding to keratinocytes in a hyaluronan-dependent way. Overexpression of wild type CD44 standard form, but not a corresponding CD44 mutant mimicking the Ser-325-phosphorylated form, was able to induce monocyte binding to keratinocytes. In conclusion, treatment of human keratinocytes with IL-1β changes the structure of their hyaluronan coat by influencing the amount, post-translational modification, and cytoskeletal association of CD44, thus enhancing monocyte retention on keratinocytes.

PARP inhibitor, olaparib ameliorates acute lung and kidney injury upon intratracheal administration of LPS in mice

We have previously shown that PARP-1 inhibition provides protection against lung inflammation in the context of asthma and acute lung injury. Olaparib is a potent new generation PARP inhibitor that has been approved for human testing. The present work was designed to evaluate its beneficial potential against LPS-induced acute lung injury and acute kidney injury upon intratracheal administration of the endotoxin in mice. Administration of olaparib at different doses, 30 min after LPS treatment showed that single intraperitoneal injection of the drug at 5 mg/kg b.wt. reduced the total number of inflammatory cells particularly neutrophils in the lungs. This was associated with reduced pulmonary edema as the total protein content in the bronchoalveolar fluid was found to be decreased substantially. Olaparib provided strong protection against LPS-mediated secondary kidney injury as reflected by restoration of serum levels of urea, creatinine, and uric acid toward normal. The drug restored the LPS-mediated redox imbalance toward normal in lung and kidney tissues as assessed by measuring malondialdehyde and GSH levels. Finally, RT-PCR data revealed that olaparib downregulates the LPS-induced expression of NF-κB-dependent genes namely TNF-α, IL-1β, and VCAM-1 in the lungs without altering the expression of total p65NF-κB. Overall, the data suggest that olaparib has a strong potential to protect against LPS-induced lung injury and associated dysfunctioning of kidney in mice. Given the fact that olaparib is approved by FDA for human testing, our findings can pave the way for testing of the drug on humans inflicted with acute lung injury.