A condition which causes deformity of the hand – leading in the most severe cases to impairment and disability – can now be successfully treated by using drugs developed in recent years for the treatment of different forms of arthritis, researchers at the University of Glasgow have found.
Dupuytren’s disease is a common and progressive fibroproliferative disorder of the hand, causing usually the little or ring finger to be pulled in towards the palm of the hand.
The deformity can impair hand movement to the extent it limits daily activities severely, including self-care and employment, reducing health-related quality of life.
There are no approved treatments for the early stages of the disease and a high recurrence in late-stage disease when therapies including surgery and injection therapy which work for only a limited length of time.
Across the UK, the prevalence of the disease is approximately 20%. In Scotland the prevalence is much higher – 40% of the population – and in Scandinavian countries, it affects around 30% of men over 60.
This is because the disease is genetic; Scots are affected more than other parts of the UK because more people carry Celtic or Irish genes.
Now, however, a team led by Mr. Neal Millar, Clinical Senior Lecturer in Orthopedic Surgery in the University’s Institute of Infection, Immunity and Inflammation, has discovered that two drugs developed in recent years for the treatment of different forms of arthritis can block the fibrotic response found in Dupuytren’s disease.
The drugs are:
- Cytokine inhibitors which has been used successfully for treating rheumatoid and other forms of arthritis for around 15 years
- JAK inhibitors which became available around five years ago, and is also used for the treatment of inflammatory arthritis.
Mr. Millar said: “Our work using patient samples from Dupuytren’s disease has discovered a key role for these drugs. We were able to reverse these fibrotic changes in human cells. Until now, there has been nothing out there for these patients.”
The two arthritis drugs are licensed for use in the treatment of that disease but under drug regulations, they must undergo further testing for use in the treatment of a different disease.
Mr. Millar and his team have submitted a patent for the discovery of the new use of the drugs. They have also been awarded a grant from the MRC (Medical Research Council) EMINENT program to conduct experimental therapeutic trials which he anticipates could start in a year’s time. All being well, the drugs could be cleared for use in Dupuytren’s disease in two to three years’ time.
A further potential use has also been uncovered as a result of the team’s work on Dupuytren’s disease. They have been able to take tissue from patients suffering from this disease to use as a surrogate for tests related to other fibrotic illnesses, such as lung and kidney fibrosis.
“One of the problems associated with these illnesses is the difficulty getting tissue from patients. We have been using tissue from Dupuytren’s disease as a surrogate as we know the process of its development as happens in liver and kidney fibrosis.
We believe that these drugs may also be effective in the treatment of other fibrotic diseases. This would offer a major breakthrough in the treatment of conditions which are life-threatening and affect hundreds of thousands of patients,” said Mr. Millar.
This study demonstrates that the local tissue environment in Dupuytren’s disease is characterized by a milieu of inflammatory cells and cytokines, which not only drive early myofibroblast transdifferentiation but also provides the environment for the fibroproliferative chronicity of this debilitating disease.
We find a milieu of cytokines drive phenotypic changes on the stromal cells, and these phenomena are dependent on STAT phosphorylation (Fig. 6), which we are able to inhibit in vitro.
Together, our results suggest that Dupuytren’s disease has a vital immune and inflammatory component driving the fibroproliferative chronicity that may be effectively treated by targeting the STAT pathway.
IL-13 is synonymous with fibrotic disorders (19, 36, 37), and we established the increased presence of mast cell–derived IL-13 in Dupuytren’s tissue. One of the principal mechanisms through which IL-13 promotes fibrosis is via proliferation of resident stromal cells.
This hyperproliferation, previously attributed in Dupuytren’s disease to TGF-β responses, encourages cells to lay down increased matrix proteins promoting clinical cord and nodule formation.
Our data suggest the presence of another core mediator of fibrosis, IL-13, can also induce significant proliferation of myofibroblasts as well as ECM production in Dupuytren’s fibrosis.
T cells are also a known source of IL-13 and are found in abundance in Dupuytren’s tissue. However, we identified the majority of T cells in Dupuytren’s tissue were IFN-γ–producing cells.
While IFN-γ is not synonymous with fibrosis (38, 39) unlike other cytokines (i.e., IL-4, IL-13, TGF-β), it has also been implicated in fibrotic pathways and pathogenesis (23, 24, 40–42).
Similar to previous publications (23, 24), we found that IFN-γ (in combination with TGF-β) was able to induce human mast cells to produce IL-13.
We believe that IFN-γ from T cells can induce mast cells to release IL-13 with subsequent fibroproliferative changes observed in disease. The data highlight a milieu of cytokines act cooperatively to induce the multicellular fibrotic pathogenesis observed in Dupuytren’s disease.
Rather than being a linear hierarchical pathway, it is likely a dynamic fluid environment leads to the multifaceted features of fibrotic disorders (Fig. 6). Recent findings also support the role of cytokine and cell cross-talk in driving fibrotic disease (11).
Both macrophages and, in particular, mast cell are synonymous with fibrotic disease, which is further elegantly highlighted by the study. Although the study primarily focused on the combined effects of TNF-α and IL-33, we believe it supports our findings.
Izadi and colleagues did not record much spontaneous IL-13 release (11), which may be due to cells being latent following disaggregation from tissue; IL-33 is known to drive IL-13 release from mast cells in disease (43).
The current study has demonstrated that IL-13 release and its downstream fibrotic effects are viable targets for therapy. As such, the findings from both studies reinforce that fibrotic disease is a result of a complex milieu of cells and cytokines working cooperatively in the pathogenesis of fibrosis.
Our data further support the notion that α-SMA–high–expressing myofibroblast phenotype is primarily due to TGF-β (fig. S3C) but reveal Dupuytren’s myofibroblasts portray another, to our knowledge, undocumented facet: higher IL-13Rα1 expression.
In addition, we were able to induce this characteristic in control fibroblasts following IFN-γ exposure in combination with TGF-β, a phenomenon previously demonstrated in eosinophils (30).
As in most cases with IFN-γ (32), the induced IL-13Rα1 change was dependent on the phosphorylation of STAT1. We importantly found increased STAT1 binding on the IL-13Rα1 gene at the enhancer and intronic sites, thereby facilitating the downstream IL-13 responsiveness.
This unique binding motif of STAT1 appears to be a hallmark of Dupuytren’s myofibroblasts and could represent an interesting therapeutic intervention in the future via epigenetic targeting.
The STAT pathway has been a therapeutic approach in other disease pathologies through the use of JAK inhibitors (44, 45), a group of receptor-associated kinases that are essential for downstream signaling cascade of a number of cytokine receptors.
Upon cytokine and receptor engagement, JAKs initiate the STAT phosphorylation, leading to STAT dimerization and, ultimately, target gene induction (44). We elected to use tofacitinib as a pan JAK inhibitor, as it has previously been shown to be effective against IFN-γ (46) and IL-13 (35) signaling in vitro, and safety and efficacy have been demonstrated in numerous clinical trials (44) including the treatment of rheumatoid arthritis.
We successfully inhibited STAT1 phosphorylation, following IFN-γ stimulation, in mast cells and control fibroblasts, resulting in no downstream increase in IL-13 secretion and IL13Rα1 expression, respectively.
Furthermore, tofacitinib treatment inhibited IL-13-induced STAT6 phosphorylation in diseased myofibroblasts, leading to reduced cell proliferation and matricellular protein up-regulation.
Together, we demonstrate that targeting of the JAK/STAT pathway can inhibit cytokine production, fibroblast-to-myofibroblast transdifferentiation, and fibroproliferation of myofibroblasts, advocating it as a translational target in Dupuytren’s disease.
While we demonstrate effective targeting of IL-13 production and signaling, we acknowledge a critical role of TGF-β in driving Dupuytren’s disease. Many of the effects we observed occur in the presence of TGF-β, while myofibroblast transdifferentiation via α-SMA expression is principally TGF-β dependent (47).
However, direct and universal inhibition of TGF-β may not be suitable given its function in a broad range of physiological pathways and various isoforms (7, 48), while in vivo studies have documented increased inflammation, tumor production, and toxicity (49–51). In addition, clinical trials have demonstrated limited long-term efficacy in fibrotic disorders to date (47). Furthermore, α-SMA expression may only be an indicator of fibrotic conditions and not causative (52); thus, direct targeting of it may be futile.
We acknowledge that our experimental datasets lack in vivo animal data. Although a number of animal models have been used to study cytokine-driven fibrotic pathogenesis, there is no well-described in vivo model available for Dupuytren’s disease.
There have been attempts to describe rodent models; however, these xenograft models rely on implanting human cells into mice or rats (53, 54).
In addition, the outcomes of using these model studies do not document any clinical-like outcomes but rather those already investigated in vitro (i.e., TGF-β levels and α-SMA and collagen expression) (55–57).
In addition, while we were able to measure collagen protein levels following IL-13 stimulation, we measure mRNA expression for other matrix proteins (tenascin-C and periostin).
However, this was primarily to highlight that changes in these genes were due directly to IL-13, and any subsequent intervention in the IL-13 pathway would impede changes in these genes. Last, while not statistically significant, we also note that our control fascia samples were on average 7 years younger than that of the Dupuytren’s samples, and thus, some aspects may be due to aging effects.
In summary, the current study establishes inflammation-driven epigenetic changes in fibroblasts and IL-13 production in the pathogenesis of Dupuytren’s disease. Dissection of the molecular pathways involved reveals pharmacological manipulation of the STAT pathways as therapeutic targets to down-regulate myofibroblast differentiation and activity.
On the basis of our findings, we suggest that repurposing of these readily available pharmaceutical agents may provide novel proof-of-concept studies in Dupuytren’s disease.
More information: Moeed Akbar et al. Attenuation of Dupuytren’s fibrosis via targeting of the STAT1 modulated IL-13Rα1 response, Science Advances (2020). DOI: 10.1126/sciadv.aaz8272