Recombinant human proteoglycan 4 lowers inflammation and atherosclerosis susceptibility in female low-density lipoprotein receptor knockout mice.

Recombinant human proteoglycan 4 (rhPRG4) is a macromolecular mucin-like glycoprotein that is classically studied as a lubricant within eyes and joints. Given that endogenously produced PRG4 is present within atherosclerotic lesions and genetic PRG4 deficiency increases atherosclerosis susceptibility in mice, in the current study we investigated the anti-atherogenic potential of chronic rhPRG4 treatment. Female low-density lipoprotein receptor knockout mice were fed an atherogenic Western-type diet for 6 weeks and injected three times per week intraperitoneally with 0.5 mg rhPRG4 or PBS as control. Treatment with rhPRG4 was associated with a small decrease in plasma-free cholesterol levels, without a change in cholesteryl ester levels. A marked increase in the number of peritoneal foam cells was detected in response to the peritoneal rhPRG4 administration, which could be attributed to elevated peritoneal leukocyte MSR1 expression levels. However, rhPRG4-treated mice exhibited significantly smaller aortic root lesions of 278 ± 21 × 103 µm2 compared with 339 ± 15 × 103 µm2 in the aortic root of control mice. The overall decreased atherosclerosis susceptibility coincided with a shift in the monocyte and macrophage polarization states towards the patrolling and anti-inflammatory M2-like phenotypes, respectively. Furthermore, rhPRG4 treatment significantly reduced macrophage gene expression levels as well as plasma protein levels of the pro-inflammatory/pro-atherogenic cytokine TNF-alpha. In conclusion, we have shown that peritoneal administration and subsequent systemic exposure to rhPRG4 beneficially impacts the inflammatory state and reduces atherosclerosis susceptibility in mice. Our findings highlight that PRG4 is not only a lubricant but also acts as an anti-inflammatory agent. KEY POINTS: Endogenously produced proteoglycan 4 is found in atherosclerotic lesions and its genetic deficiency in mice is associated with enhanced atherosclerosis susceptibility. In this study we investigated the anti-atherogenic potential of chronic treatment with recombinant human PRG4 in hypercholesterolaemic female low-density lipoprotein receptor knockout mice. We show that recombinant human PRG4 stimulates macrophage foam cell formation, but also dampens the pro-inflammatory state of monocyte/macrophages, eventually leading to a significant reduction in plasma TNF-alpha levels and a lowered atherosclerosis susceptibility. Our findings highlight that peritoneal recombinant human PRG4 treatment can execute effects both locally and systemically and suggest that it will be of interest to study whether rhPRG4 treatment is also able to inhibit the progression and/or induce regression of previously established atherosclerotic lesions.

Preclinical Animal Studies of Intravesical Recombinant Human Proteoglycan 4 as a Novel Potential Therapy for Diseases Resulting From Increased Bladder Permeability.

OBJECTIVE: To test in an animal model the hypothesis that recombinant human proteoglycan 4 (rhPRG4; lubricin), a highly O-glycosylated mucin-like glycoprotein, may be a novel surface-active therapeutic for treating bladder permeability with comorbid bowel permeability. Previously we showed that inducing bladder permeability in rats with dilute protamine sulfate (PS) produced colonic permeability and visceral hypersensitivity, suggesting increased bladder permeability could represent an etiologic factor in both interstitial cystitis-bladder pain syndrome and irritable bowel syndrome. METHODS: We used an animal model of catheterized ovariectomized female rats instilled intravesically with 1 mg/mL PS for 10 minutes that after 24 hours were treated with 1.2 mg/mL lubricin or with vehicle alone. After 24 hours the bladder and colon were removed and permeability assessed electrophysiologically with the Ussing chamber to measure the transepithelial electrical resistance. A second set of rats was treated identically, except permeability was assessed on day 3 and on day 5 using contrast-enhanced magnetic resonance imaging with gadolinium diethylenetriamine penta-acetic acid instilled into the bladder. RESULTS: Intravesical lubricin reversed bladder permeability induced by PS and prevented the concomitant increase in permeability induced in the bowel (organ crosstalk). The protective effect was confirmed with magnetic resonance imaging, and because individual rats could be followed over time, the impermeability of the bladder restored by rhPRG4 remained for 5 days. CONCLUSION: These data indicate that instillation of rhPRG4 into a permeable bladder can restore its normally impermeable state, and that the effect lasts for 5 days and also prevents bowel symptoms often comorbid with interstitial cystitis-bladder pain syndrome.

A Two-Week, Randomized, Double-masked Study to Evaluate Safety and Efficacy of Lubricin (150 µg/mL) Eye Drops Versus Sodium Hyaluronate (HA) 0.18% Eye Drops (Vismed®) in Patients with Moderate Dry Eye Disease.

PURPOSE: The objective of this clinical trial (NCT02507934) was to assess the efficacy and safety of recombinant human lubricin as compared to a 0.18% sodium hyaluronate (HA) eye drop in subjects with moderate dry eye disease (DED). METHODS: DEWS Grade 2-3 subjects were randomized to use lubricin (N=19, 51.9 ± 11.8 years) or HA (N=20, 61.8 ± 13.3 years). After a saline washout period, subjects administered BID therapy for 7 days, followed by instillation as needed (2-6 drops per eye) for 7 days. Visual analog scale (VAS) including foreign body sensation, burning/stinging, itching, pain, sticky feeling, blurred vision and photophobia were primary outcomes, with secondary endpoints of corneal fluorescein staining, Schirmer test, tear film breakup time (TFBUT), eyelid and conjunctival erythema and number of instillations compared at day 14. RESULTS: The primary endpoint was met. Lubricin supplementation achieved greater than a 72% reduction from baseline in foreign body sensation (P<.013), burning/stinging, pain, sticky feeling (P<.0432), blurred vision (P<.0013), and photophobia (P<.011) in at least one eye. Lubricin also showed significant improvement in fluorescein staining (OD/OS: 43.8%/50.0%, vs. 26.5%/23.3%, P<.0398, P<.0232), TFBUT (P<.010), SANDE frequency (P<.0435), eyelid erythema (P<.004), conjunctival erythema (P<.0013), and instillations (P<.04) as compared to HA. No treatment-related adverse events occurred during the investigation. CONCLUSIONS: Recombinant human lubricin was shown to produce significant improvement in both signs and symptoms of dry eye disease as compared to HA.