Abstract Background/Aims Activated fibroblasts, called myofibroblasts, are responsible for the fibrosis seen in scleroderma. How to block myofibroblast activation and activity in scleroderma is unknown, but CCN3, a member of the CCN family of matricellular proteins, is anti-fibrotic and counteracts the profibrotic activity of the related protein CCN2. We have identified BLR-200 as a CCN3-derived peptide that retains CCN3’s antifibrotic properties in bleomycin-induced skin fibrosis. However, if CCN3’s and BLR-200’s antifibrotic properties translate to scleroderma patients is unknown. Methods To test the hypothesis that reduced CCN3 levels may exist in scleroderma patients, we used ELISAs to detect the amount of CCN2 and CCN3 in serum of healthy controls, early-onset diffuse (<24 months duration) scleroderma patients and those of later (>5 years) duration. To identify the fibroblast populations whose activation by bleomycin is suppressed by BLR-200, we conducted scRNAseq analysis of fibroblasts labelled postnatally with green fluorescent protein using mTmG mice, subjected or not to bleomycin-induced skin fibrosis in the presence or absence of BLR-200, that expressed a tamoxifen-dependent cre recombinase expressed under the control of a universal fibroblast-specific promoter/enhancer. Results CCN2 and CCN3 serum levels correlated well among healthy volunteers (controls) (r2=0.39, p < 0.03, N = 20), whereas scleroderma patients of < 2 years and of > 5 years duration showed patient-specific dysregulation of CCN2 and CCN3 protein levels (r2=0.048 and r2=0.116, respectively, N = 20). CCN2 and CCN3 levels increased in serum with patients of early duration (p < 0.05 vs p < 0.0001, respectively); however, increases in CCN3, but not CCN2, levels were observed in patients with late duration (p < 0.001 vs ns, respectively). In mice subjected to bleomycin-induced skin fibrosis, lineage tracing and scRNA-seq analyses revealed that myofibroblasts are derived from Pi16+/Col15+ve “universal” fibroblasts (N = 6, p < 0.01). BLR-200 prevented myofibroblast differentiation of Pi16+/Col15+ve “universal” fibroblasts in response to bleomycin toward an engrailed-1/Col8A1-positive subset of “universal” fibroblasts, a pro-fibrotic cell type previously shown to specifically upregulated in skin derived from scleroderma patients with active disease. Conclusion Given what is known about the relative activities of CCN2 and CCN3 in vivo, it is likely that serum levels of CCN3 rise in scleroderma patients in the body’s attempt to suppress CCN2-dependent fibrosis. Why this dysregulation appears to be patient-specific is unclear and requires further investigation. BLR-200 specifically targets the prevention of formation of an engrailed-1/Col8A1-positive fibroblast subpopulation that is specifically upregulated in skin in scleroderma patients. Therefore, BLR-200 appears to be a novel anti-fibrotic agent of potential translational relevance, particularly to patients with low serum levels of CCN3. Disclosure A. Leask: None. R.J. Stratton: None. B.A. Abdi: None. Z.J. Kannan: None. J. Nguyen: None. B.L. Riser: Corporate appointments; CEO, BLR Bio, LLC.

Scleroderma (systemic sclerosis; SSc) is an autoimmune connective tissue disease characterized by progressive fibrosis of the skin and internal organs. Lung fibrosis is a significant cause of mortality in SSc. Alterations in the expression of members of the cellular communication network (CCN) family of matricellular proteins are a hallmark of SSc. Of the CCN family, CCN2 is profibrotic and CCN3 is antifibrotic. We have developed a CCN3-derived peptide, BLR-200, as an anti-fibrotic therapeutic. BLR-200 has been given orphan drug designation by the US Food and Drug Administration. Whether BLR-200 has antifibrotic activity in a model of SSc lung fibrosis is unknown. We use Western blot analysis to assess CCN3 expression levels in fibroblasts from healthy individuals and individuals with SSc. We use the bleomycin model (one dose of bleomycin, injected intratracheally at d0) of lung fibrosis (the industry-standard method of assessing experimental SSc lung fibrosis) to assess the effect of BLR-200 (subcutaneous injection, 3 times/week, over 21 days) on histological and molecular markers of lung fibrogenesis. CCN3 protein expression is reduced in SSc fibroblasts (N = 3, p < 0.05). Injection of BLR-200, compared to control scrambled peptide, significantly attenuated bleomycin-induced lung fibrosis, as visualized by histological (Ashcroft score of Trichrome-stained sections), protein (hydroxyproline collagen assay), lung weight, and mRNA (expression of CCN1, CCN2, COL1A2, ACTA2, PLOD2 as assessed by real-time polymerase chain reaction) analyses (all N = 5, all p < 0.05). As BLR-200 reduces bleomycin-induced lung fibrosis, BLR-200 may represent a novel treatment for SSc lung fibrosis. P. Chitturi: None. S. Xu: None. R.J. Stratton: None. B.L. Riser: Corporate appointments; CEO, BLR Bio, LLC. A. Leask: Grants/research support; Canadian Institutes of Health Research.

Background/Aims Effective therapy for skin fibrosis in scleroderma (systemic sclerosis: SSc) remains an unmet clinical challenge. Persistently activated M2 macrophages are believed to stimulate myofibroblasts in the disease microenvironment creating a pro-fibrotic niche in the skin. Expression of the anti-fibrotic matricellular protein CCN3 is reduced in animal models of fibrosis. We have identified a small peptide based on an amino acid sequence in CCN3, BLR-200, which mimics the anti-fibrotic activity of CCN3, and propose that BLR-200 could be used to treat patients in whom lack of CCN3 activity is permissive for fibrosis. However, whether there is lack of CCN3 activity in SSc and whether BLR-200 has effective anti-fibrotic activity in SSc are unknown. Methods We used ELISAs (R&D Systems) to detect CCN3 and the M2 macrophage marker CD206 in the serum of scleroderma patients with early stage diffuse subset disease (within two years of disease onset), those with late-stage diffuse subset disease (over five years duration) as well as healthy controls (all n=20). The bleomycin-induced mouse model of skin scleroderma, in which bleomycin is injected subcutaneously every day for 21 days, was used to assess the antifibrotic ability of BLR200 in vivo. Results In scleroderma serum, CCN3 was significantly reduced, relative to matched healthy controls and patients with inactive disease, in early onset scleroderma patients with active disease that show elevated CD206 levels (p<0.01). In the mouse model of human SSc, compared to injection with a scrambled control peptide and relative to control mice treated with phosphate buffered saline, injection with BLR-200 prevented bleomycin-induced changes in collagen deposition, myofibroblast differentiation and skin thickness as measured by Trichrome stain, indirect immunofluorescence analysis with an anti-a-smooth muscle actin antibody, and morphometric analysis, respectively (N=8 mice per group, p<0.05). Similarly, RNA sequencing and real-time polymerase chain reaction analysis revealed that BLR-200 significantly impaired the ability of bleomycin to induce expression of fibrogenic genes such as: integrin alpha 11, CCN2, CCN1, Smad3, wnt4, YAP1 and tenascin-C (all N=5, p<0.05). Spatial transcriptomics analysis revealed that BLR-200 impaired bleomycin-induced alterations in skin cell populations, including the activation and expansion of epithelial and reticular fibroblast niches and the induction of Wnt, hippo, focal adhesion and actin cytoskeleton gene expression cluster, all of which are known to be activators of fibrosis and myofibroblast activation and persistence. Conclusion CCN3 expression is reduced in serum of scleroderma patients with active skin disease that show M2 macrophage activation as visualized by elevated CD206 levels. Since BLR-200 has antifibrotic activity in the bleomycin model of skin scleroderma, our data are consistent with the hypothesis that BLR-200 could be used to block fibrosis progression in early onset diffuse scleroderma patients who possess both low CCN3 and high CD206 in serum. Disclosure J. Nguyen: None. K. Zestranjyan: None. S. Xu: None. B.L. Riser: Corporate appointments; CEO of BLR Bio. R.J. Stratton: None. A. Leask: None.

Abstract Background/Aims Effective therapy for skin fibrosis in scleroderma (systemic sclerosis: SSc) remains an unmet clinical challenge. Persistently activated M2 macrophages are believed to stimulate myofibroblasts in the disease microenvironment creating a pro-fibrotic niche in the skin. Expression of the anti-fibrotic matricellular protein CCN3 is reduced in animal models of fibrosis. We have identified a small peptide based on an amino acid sequence in CCN3, BLR-200, which mimics the anti-fibrotic activity of CCN3, and propose that BLR-200 could be used to treat patients in whom lack of CCN3 activity is permissive for fibrosis. However, whether there is lack of CCN3 activity in SSc and whether BLR-200 has effective anti-fibrotic activity in SSc are unknown. Methods We used ELISAs (R&D Systems) to detect CCN3 and the M2 macrophage marker CD206 in the serum of scleroderma patients with early stage diffuse subset disease (within two years of disease onset), those with late-stage diffuse subset disease (over five years duration) as well as healthy controls (all n = 20). The bleomycin-induced mouse model of skin scleroderma, in which bleomycin is injected subcutaneously every day for 21 days, was used to assess the antifibrotic ability of BLR200 in vivo. Results In scleroderma serum, CCN3 was significantly reduced, relative to matched healthy controls and patients with inactive disease, in early onset scleroderma patients with active disease that show elevated CD206 levels (p < 0.01). In the mouse model of human SSc, compared to injection with a scrambled control peptide and relative to control mice treated with phosphate buffered saline, injection with BLR-200 prevented bleomycin-induced changes in collagen deposition, myofibroblast differentiation and skin thickness as measured by Trichrome stain, indirect immunofluorescence analysis with an anti-a-smooth muscle actin antibody, and morphometric analysis, respectively (N = 8 mice per group, p < 0.05). Similarly, RNA sequencing and real-time polymerase chain reaction analysis revealed that BLR-200 significantly impaired the ability of bleomycin to induce expression of fibrogenic genes such as: integrin alpha 11, CCN2, CCN1, Smad3, wnt4, YAP1 and tenascin-C (all N = 5, p < 0.05). Spatial transcriptomics analysis revealed that BLR-200 impaired bleomycin-induced alterations in skin cell populations, including the activation and expansion of epithelial and reticular fibroblast niches and the induction of Wnt, hippo, focal adhesion and actin cytoskeleton gene expression cluster, all of which are known to be activators of fibrosis and myofibroblast activation and persistence. Conclusion CCN3 expression is reduced in serum of scleroderma patients with active skin disease that show M2 macrophage activation as visualized by elevated CD206 levels. Since BLR-200 has antifibrotic activity in the bleomycin model of skin scleroderma, our data are consistent with the hypothesis that BLR-200 could be used to block fibrosis progression in early onset diffuse scleroderma patients who possess both low CCN3 and high CD206 in serum. Disclosure J. Nguyen: None. K. Zestranjyan: None. S. Xu: None. B.L. Riser: Corporate appointments; CEO of BLR Bio. R.J. Stratton: None. A. Leask: None.

Hippo was first identified in a genetic screen as a protein that suppressed proliferation and cell growth. Subsequently, it was shown that hippo acted in a so-called canonical cascade to suppress yorkie, the Drosophila equivalent of Yes-activated protein (YAP), a mechanosensitive transcriptional cofactor that enhances the activity of the TEAD family of transcription factors. YAP promotes fibrosis, activation of cancer-associated fibroblasts, angiogenesis and cancer cell invasion. YAP activates the expression of the matricellular proteins CCN1 (cyr61) and CCN2 (ctgf), themselves mediators of fibrogenesis and oncogenesis, and coordination of matrix deposition and angiogenesis. This review discusses how therapeutically targeting YAP through YAP inhibitors verteporfin and celastrol and its downstream mediators CCN1 and CCN2 might be useful in treating melanoma.

Approximately 45% of the deaths in the developed world result from conditions with a fibrotic component. Although no specific, focused anti-fibrotic therapies have been approved for clinical use, a long-standing concept is that targeting CCN proteins may be useful to treat fibrosis. Herein, we summarize current data supporting the concept that targeting CCN2 may be a viable anti-fibrotic approach to treat scleroderma. Testing this hypothesis has been made possible by using a mouse model of inflammation-driven skin and lung fibrosis.

The prominent desmoplastic stroma of pancreatic ductal adenocarcinoma (PDAC) is a determinant factor in tumor progression and a major barrier to the access of chemotherapy. The PDAC microenvironment therefore appears to be a promising therapeutic target. CCN2/CTGF is a profibrotic matricellular protein, highly present in the PDAC microenvironment and associated with disease progression. Here we have investigated the therapeutic value of the CCN2-targeting BLR100 and BLR200, two modified synthetic peptides derived from active regions of CCN3, an endogenous inhibitor of CCN2. In a murine orthotopic PDAC model, the two peptides, administered as monotherapy at low doses (approximating physiological levels of CCN3), had tumor inhibitory activity that increased with the dose. The peptides affected the tumor microenvironment, inhibiting fibrosis and vessel formation and reducing necrosis. Both peptides were active in preventing ascites formation. An increased activity was obtained in combination regimens, administering BLR100 or BLR200 with the chemotherapeutic drug gemcitabine. Pharmacokinetic analysis indicated that the improved activity of the combination was not mainly determined by the substantial increase in gemcitabine delivery to tumors, suggesting other effects on the tumor microenvironment. The beneficial remodeling of the tumor stroma supports the potential value of these CCN3-derived peptides for targeting pathways regulated by CCN2 in PDAC.

Vascular calcification significantly contributes to mortality in chronic kidney disease (CKD) patients. Sevelamer and pyrophosphate (PPi) have proven to be effective in preventing vascular calcification, the former by controlling intestinal phosphate absorption, the latter by directly interfering with the hydroxyapatite crystal formation. Since most patients present with established vascular calcification, it is important to evaluate whether these compounds may also halt or reverse the progression of preexisting vascular calcification. CKD and vascular calcification were induced in male Wistar rats by a 0.75 % adenine low protein diet for 4 weeks. Treatment with PPi (30 or 120 µmol/kg/day), sevelamer carbonate (1500 mg/kg/day) or vehicle was started at the time point at which vascular calcification was present and continued for 3 weeks. Hyperphosphatemia and vascular calcification developed prior to treatment. A significant progression of aortic calcification in vehicle-treated rats with CKD was observed over the final 3-week period. Sevelamer treatment significantly reduced further progression of aortic calcification as compared to the vehicle control. No such an effect was seen for either PPi dose. Sevelamer but not PPi treatment resulted in an increase in both osteoblast and osteoid perimeter. Our study shows that sevelamer was able to reduce the progression of moderate to severe preexisting aortic calcification in a CKD rat model. Higher doses of PPi may be required to induce a similar reduction of severe established arterial calcification in this CKD model.

The CCN family of matricellular signaling proteins is emerging as a unique common link across multiple diseases and organs related to injury and repair. They are now being shown to play a central role in regulating the pathways to the initiation and resolution of normal wound healing and fibrosis in response to multiple forms of injury. Similarly, it is also emerging that they play a key role in regulating the establishment, growth, metastases and tissue regeneration in many forms of cancer via the interaction of cancer cells with the tumor stroma. Evidence has been recently provided that these proteins do not act independently but are co-regulated working in a yin/yang manner to alter the outcome of both normal physiological processes as well as pathology. The purpose of this review is to twofold. First, it will summarize work to date supporting CCN2 as a therapeutic target in the formation and progression of renal, skin, and other organ fibrosis, as well as cancer stroma formation. Second, it will highlight recent evidence for CCN3 as a counter-regulator and a potential therapeutic agent in these diseases with an exciting, novel potential to both treat and then restore tissue homeostasis in those afflicted by these devastating disorders.

Chronic kidney disease (CKD) is generally associated with disturbances of mineral and bone metabolism. They contribute to the development of vascular calcification (VC), a strong, independent predictor of cardiovascular risk. Pyrophosphate (PPi), an endogenous inhibitor of hydroxyapatite formation, has been shown to slow the progression of VC in uremic animals. Since in patients with CKD treatment is usually initiated for already existing calcifications, we aimed to compare the efficacy of PPi therapy with that of the phosphate binder sevelamer, using a uremic apolipoprotein-E knockout mouse model with advanced VCs. After CKD creation or sham surgery, 12-week-old female mice were randomized to one sham group and four CKD groups (n = 18–19/group). Treatment was initiated 8 weeks after left nephrectomy allowing prior VC development. Uremic groups received either intraperitoneal PPi (high dose, 1.65 mg/kg or low dose, 0.33 mg/kg per day), oral sevelamer (3 % in diet), or placebo treatment for 8 weeks. Both intima and media calcifications worsened with time in placebo-treated CKD mice, based on both quantitative image analysis and biochemical measurements. Progression of calcification between 8 and 16 weeks was entirely halted by PPi treatment, as it was by sevelamer treatment. PPi did not induce consistent bone histomorphometry changes. Finally, the beneficial vascular action of PPi probably involved mechanisms different from that of sevelamer. Further studies are needed to gain more precise insight into underlying mechanisms and to see whether PPi administration may also be useful in patients with CKD and VC.

Vascular calcification (VC) is a risk factor for cardiovascular mortality in the setting of chronic kidney disease (CKD). Pyrophosphate (PPi), an endogenous molecule that inhibits hydroxyapatite crystal formation, has been shown to prevent the development of VC in animal models of CKD. However, the possibility of harmful effects of exogenous administration of PPi on bone requires further investigation. To this end, we examined by histomorphometry the bone of CKD mice after intraperitoneal PPi administration. After CKD creation or sham surgery, 10-week-old female apolipoprotein-E knockout (apoE(-/-)) mice were randomized to one non-CKD group or 4 CKD groups (n = 10-35/group) treated with placebo or three distinct doses of PPi, and fed with standard diet. Eight weeks later, the animals were killed. Serum and femurs were sampled. Femurs were processed for bone histomorphometry. Placebo-treated CKD mice had significantly higher values of osteoid volume, osteoid surface and bone formation rate than sham-placebo mice with normal renal function. Slightly higher osteoid values were observed in CKD mice in response to very low PPi dose (OV/BV, O. Th and ObS/BS) and, for one parameter measured, to high PPi dose (O. Th), compared to placebo-treated CKD mice. Treatment with PPi did not modify any other structural parameters. Mineral apposition rates, and other parameters of bone formation and resorption were not significantly different among the treated animal groups or control CKD placebo group. In conclusion, PPi does not appear to be deleterious to bone tissue in apoE(-/-) mice with CKD, although a possible stimulatory PPi effect on osteoid formation may be worth further investigation.

Introduction Encapsulating peritoneal sclerosis (EPS) is a devastating complication of peritoneal dialysis (PD). The pathogenesis is not exactly known and no preventive strategy or targeted medical therapy is available. CCN2 has both pro-fibrotic and pro-angiogenic actions and appears an attractive target. Therefore, we studied peritoneal expression of CCN2, as well as TGFβ1 and VEGF, in different stages of peritoneal fibrosis. Materials and methods Sixteen PD patients were investigated and compared to 12 hemodialysis patients and four pre-emptively transplanted patients. Furthermore, expression was investigated in 12 EPS patients in comparison with 13 PD and 12 non-PD patients without EPS. Peritoneal tissue was taken during kidney transplantation procedure or during EPS surgery. In a subset of patients, CCN2 protein levels in peritoneal effluent and plasma were determined. Samples were examined by qPCR, histology, immunohistochemistry, and ELISA. Results Peritoneal CCN2 expression was 5-fold higher in PD patients compared to pre-emptively transplanted patients (P<0.05), but did not differ from hemodialysis patients. Peritoneal expression of TGFβ1 and VEGF were not different between the three groups; neither was peritoneal thickness. Peritoneum of EPS patients exhibited increased expression of CCN2 (35-fold, P<0.001), TGFβ1 (24-fold, P<0.05), and VEGF (77-fold, P<0.001) compared to PD patients without EPS. In EPS patients, CCN2 protein was mainly localized in peritoneal endothelial cells and fibroblasts. CCN2 protein levels were significantly higher in peritoneal effluent of EPS patients compared to levels in dialysate of PD patients (12.0±4.5 vs. 0.91±0.92 ng/ml, P<0.01), while plasma CCN2 levels were not increased. Conclusions Peritoneal expression of CCN2, TGFβ1, and VEGF are significantly increased in EPS patients. In early stages of peritoneal fibrosis, only CCN2 expression is slightly increased. Peritoneal CCN2 overexpression in EPS patients is a locally driven response. The potential of CCN2 as biomarker and target for CCN2-inhibiting agents to prevent or treat EPS warrants further study.

Fibrosis is at the core of the high morbidity and mortality rates associated with the complications of diabetes and obesity, including diabetic nephropathy (DN), without any US Food and Drug Administration-approved drugs with this specific target. We recently provided the first evidence that the matricellular protein CCN3 (official symbol NOV) functions in a reciprocal manner, acting on the profibrotic family member CCN2 to inhibit fibrosis in a mesangial cell model of DN. Herein, we used the BT/BR ob/ob mouse as a best model of human obesity and DN progression to determine whether recombinant human CCN3 could be used therapeutically, and the mechanisms involved. Eight weeks of thrice-weekly i.p. injections (0.604 and 6.04 μg/kg of recombinant human CCN3) beginning in early-stage DN completely blocked and/or reversed the up-regulation of mRNA expression of kidney cortex fibrosis genes (CCN2, Col1a2, TGF-β1, and PAI-1) seen in placebo-treated diabetic mice. The treatment completely blocked glomerular fibrosis, as determined by altered mesangial expansion and deposition of laminin. Furthermore, it protected against, or reversed, podocyte loss and kidney function reduction (rise in plasma creatinine concentration); albuminuria was also greatly reduced. This study demonstrates the potential efficacy of recombinant human CCN3 treatment in DN and points to mechanisms operating at multiple levels or pathways, upstream (eg, protecting against cell injury) and downstream (eg, regulating CCN2 activity and extracellular matrix metabolism).