TGF-β and myofibroblasts play a key role in fibrosis, characterized by aberrant synthesis and deposition of extracellular matrix (ECM) proteins, such as fibronectin (Fn) and collagen type I. There are two major roles played by integrins in the fibrotic pathology: (i) Fn-integrin interaction, coupled with cytokines like TGF-β, facilitates the self-polymerization of Fn and regulates cell–matrix fibrillar adhesions, thereby promoting fibrillogenesis; (ii) Integrin interaction with an RGD (arginine-glycine–aspartic) consensus sequence in the latent TGF-β, resulting in its activation. This study describes an anti-fibrotic strategy using a combination of two antibodies: Fn52 (targeted against the N-terminal 30 kDa region of fibronectin, a major site for Fn self-association) and its engineered form, Fn52RGDS (which binds to integrins). Interestingly, a synergistic effect of the cocktail in causing a decline in fibrotic features was confirmed in the context of fibrotic posterior capsular opacification (PCO), mediated by the lens epithelial cells (left behind after cataract surgery). Inclusion of Fn52RGDS to Fn52 aids in better diffusion of the antibodies; such combination therapies could be useful in the context of pathologies involving extensive remodeling of the fibronectin matrix, where the thick ECM offers a major challenge for efficient drug delivery.

Recent Mucorales-mediated outbreaks of infections and an association of fungal infection with COVID-19 cases, as observed for COVID-19-associated mucormycosis (CAM), have posed new challenges for the management of patients in critical care units. Diabetes and hyperglycemia are integrally linked to the severity of COVID-19, and uncontrolled diabetes mellitus and COVID-19 have recently been (independently or in combination) associated with the emergence of aggressive mucormycosis due to attendant defects in innate immune recognition pathways. Therefore, the identification of novel global cellular stressors upregulated during diabetes to understand the contribution of diabetes-associated metabolic vulnerabilities can help build a Metabolic-Stress-Associated Interactome (MSAI). This interactome can help reshape the metabolic inflammation (meta-inflammation) underlying the clinical manifestations of COVID-19 to facilitate the rational design of effective therapies for COVID-19 and CAM. Accordingly, an important area of research in COVID-19 therapeutics is engaged with identifying diabetes-associated pan-cellular stressors to understand their role in immune deregulation during COVID-19 and CAM, including investigating the distant trans-neuro-vascular–endocrine axis’s role in coordinating cellular-stress recognition, transmission, compensation, and decompensation during inter-organ regulation of metabolic homeostasis in diabetes. We reviewed clinico-pathological and laboratory data to propose potential diabetes-linked novel neo-vulnerabilities that can reshape the olfactory mucosal immune landscape during airway infections such as COVID-19 and CAM.

Fibrosis is characterized by excessive accumulation of scar tissue as a result of exaggerated deposition of extracellular matrix (ECM), leading to tissue contraction and impaired function of the organ. Fibronectin (Fn) is an essential component of the ECM, and plays an important role in fibrosis. One such fibrotic pathology is that of proliferative vitreoretinopathy (PVR), a sight-threatening complication which develops as a consequence of failure of surgical repair of retinal detachment. Such patients often require repeated surgeries for retinal re-attachment; therefore, a preventive measure for PVR is of utmost importance. The contractile membranes formed in PVR, are composed of various cell types including the retinal pigment epithelial cells (RPE); fibronectin is an important constituent of the ECM surrounding these cells. Together with the vitreous, fibronectin creates microenvironments in which RPE cells proliferate. We have successfully developed a dual-action, fully human, fibronectin-specific single chain variable fragment antibody (scFv) termed Fn52RGDS, which acts in two ways: i) binds to cryptic sites in fibronectin, and thereby prevents its self polymerization/fibrillogenesis, and ii) interacts with the cell surface receptors, ie., integrins (through an attached “RGD” sequence tag), and thereby blocks the downstream cell signaling events. We demonstrate the ability of this antibody to effectively reduce some of the hallmark features of fibrosis - migration, adhesion, fibronectin polymerization, matrix metalloprotease (MMP) expression, as well as reduction of collagen gel contraction (a model of fibrotic tissue remodeling). The data suggests that the antibody can be used as a rational, novel anti-fibrotic candidate.

Induction of posterior vitreous detachment (PVD) by pharmacologic vitreolysis has been largely attempted through the use of enzymatic reagents. Ocriplasmin has been the only FDA-approved clinical reagent so far. Several adverse effects of ocriplasmin have emerged, however, and the search for alternative PVD-inducing reagents continues. Since i) collagen forms an important structural component of the vitreous, and ii) strong vitreo-retinal adhesions exist between the cortical vitreous and the internal limiting membrane (ILM) of the retina, an effective PVD-inducing reagent would require both, vitreous liquefaction, and concurrent dehiscence of vitreoretinal adhesion, without being toxic to retinal cells. We designed a combination of two reagents to achieve these two objectives; a triple helix-destabilizing collagen binding domain (CBD), and a fusion of RGD (integrin-binding) tripeptide with CBD (RCBD) to facilitate separation of posterior cortical vitreous from retinal surface. Based on in vitro, ex-vivo, and in vivo experiments, we show that a combination of CBD and RCBD displays potential for safe pharmacologic vitreolysis. Our findings assume significance in light of the fact that synthetic RGD-containing peptides have already been used for inhibition of tumor cell invasion. Proteins such as variants of collagen binding domains could have extended therapeutic uses in the future.