Development and international validation of custom-engineered and code-free deep-learning models for detection of plus disease in retinopathy of prematurity: a retrospective study.

BACKGROUND: Retinopathy of prematurity (ROP), a leading cause of childhood blindness, is diagnosed through interval screening by paediatric ophthalmologists. However, improved survival of premature neonates coupled with a scarcity of available experts has raised concerns about the sustainability of this approach. We aimed to develop bespoke and code-free deep learning-based classifiers for plus disease, a hallmark of ROP, in an ethnically diverse population in London, UK, and externally validate them in ethnically, geographically, and socioeconomically diverse populations in four countries and three continents. Code-free deep learning is not reliant on the availability of expertly trained data scientists, thus being of particular potential benefit for low resource health-care settings. METHODS: This retrospective cohort study used retinal images from 1370 neonates admitted to a neonatal unit at Homerton University Hospital NHS Foundation Trust, London, UK, between 2008 and 2018. Images were acquired using a Retcam Version 2 device (Natus Medical, Pleasanton, CA, USA) on all babies who were either born at less than 32 weeks gestational age or had a birthweight of less than 1501 g. Each images was graded by two junior ophthalmologists with disagreements adjudicated by a senior paediatric ophthalmologist. Bespoke and code-free deep learning models (CFDL) were developed for the discrimination of healthy, pre-plus disease, and plus disease. Performance was assessed internally on 200 images with the majority vote of three senior paediatric ophthalmologists as the reference standard. External validation was on 338 retinal images from four separate datasets from the USA, Brazil, and Egypt with images derived from Retcam and the 3nethra neo device (Forus Health, Bengaluru, India). FINDINGS: Of the 7414 retinal images in the original dataset, 6141 images were used in the final development dataset. For the discrimination of healthy versus pre-plus or plus disease, the bespoke model had an area under the curve (AUC) of 0·986 (95% CI 0·973-0·996) and the CFDL model had an AUC of 0·989 (0·979-0·997) on the internal test set. Both models generalised well to external validation test sets acquired using the Retcam for discriminating healthy from pre-plus or plus disease (bespoke range was 0·975-1·000 and CFDL range was 0·969-0·995). The CFDL model was inferior to the bespoke model on discriminating pre-plus disease from healthy or plus disease in the USA dataset (CFDL 0·808 [95% CI 0·671-0·909, bespoke 0·942 [0·892-0·982]], p=0·0070). Performance also reduced when tested on the 3nethra neo imaging device (CFDL 0·865 [0·742-0·965] and bespoke 0·891 [0·783-0·977]). INTERPRETATION: Both bespoke and CFDL models conferred similar performance to senior paediatric ophthalmologists for discriminating healthy retinal images from ones with features of pre-plus or plus disease; however, CFDL models might generalise less well when considering minority classes. Care should be taken when testing on data acquired using alternative imaging devices from that used for the development dataset. Our study justifies further validation of plus disease classifiers in ROP screening and supports a potential role for code-free approaches to help prevent blindness in vulnerable neonates. FUNDING: National Institute for Health Research Biomedical Research Centre based at Moorfields Eye Hospital NHS Foundation Trust and the University College London Institute of Ophthalmology. TRANSLATIONS: For the Portuguese and Arabic translations of the abstract see Supplementary Materials section.

Magnetic Oculomotor Prosthetics for Acquired Nystagmus.

PURPOSE: Acquired nystagmus, a highly symptomatic consequence of damage to the substrates of oculomotor control, often is resistant to pharmacotherapy. Although heterogeneous in its neural cause, its expression is unified at the effector-the eye muscles themselves-where physical damping of the oscillation offers an alternative approach. Because direct surgical fixation would immobilize the globe, action at a distance is required to damp the oscillation at the point of fixation, allowing unhindered gaze shifts at other times. Implementing this idea magnetically, herein we describe the successful implantation of a novel magnetic oculomotor prosthesis in a patient. DESIGN: Case report of a pilot, experimental intervention. PARTICIPANT: A 49-year-old man with longstanding, medication-resistant, upbeat nystagmus resulting from a paraneoplastic syndrome caused by stage 2A, grade I, nodular sclerosing Hodgkin's lymphoma. METHODS: We designed a 2-part, titanium-encased, rare-earth magnet oculomotor prosthesis, powered to damp nystagmus without interfering with the larger forces involved in saccades. Its damping effects were confirmed when applied externally. We proceeded to implant the device in the patient, comparing visual functions and high-resolution oculography before and after implantation and monitoring the patient for more than 4 years after surgery. MAIN OUTCOME MEASURES: We recorded Snellen visual acuity before and after intervention, as well as the amplitude, drift velocity, frequency, and intensity of the nystagmus in each eye. RESULTS: The patient reported a clinically significant improvement of 1 line of Snellen acuity (from 6/9 bilaterally to 6/6 on the left and 6/5-2 on the right), reflecting an objectively measured reduction in the amplitude, drift velocity, frequency, and intensity of the nystagmus. These improvements were maintained throughout a follow-up of 4 years and enabled him to return to paid employment. CONCLUSIONS: This work opens a new field of implantable therapeutic devices-oculomotor prosthetics-designed to modify eye movements dynamically by physical means in cases where a purely neural approach is ineffective. Applied to acquired nystagmus refractory to all other interventions, it is shown successfully to damp pathologic eye oscillations while allowing normal saccadic shifts of gaze.

Long-term Surgical Outcomes for Vertical Deviations in Thyroid Eye Disease.

INTRODUCTION: Vertical deviations in thyroid eye disease (TED) can present a surgical challenge due to the difficulty and unpredictability of surgery and the high risk of postoperative drift towards overcorrection. This study reports the postoperative outcomes of patients who underwent adjustable vertical strabismus surgery with Vicryl sutures for thyroid eye disease. METHODS: We reviewed the records of patients seen for vertical TED strabismus surgery from January 2005 through December 2009. Clinical details were recorded preoperatively, post-adjustment, and at 3 weeks, 3 months, and 1 year postoperatively. RESULTS: The study included 42 patients. Mean age was 62.4 years and 70% were female. All patients were diplopic preoperatively. The mean near vertical deviation was 21.1 prism diopters (PD) preoperatively, 4.0 PD at 3 weeks postoperatively, 5.0 PD at 3 months, and 4.4 PD at 1 year (all mean results representing undercorrection). 71.4% were free of diplopia postoperatively. Seven patients required further surgery, 2 patients needed further botulinum toxin A. Eight patients experienced an overcorrection; five at 3 weeks, seven at 3 months, and eight at 1 year. There was a significant difference in the mean near angle at tie-off post-adjustment in the patients that overcorrected compared to those that did not reverse (3.1 PD vs 7.1 PD; P=0.005). DISCUSSION: Adjustable surgery for vertical strabismus in thyroid eye disease may result in late overcorrection and the need for further intervention. We propose that aiming for an immediate post-adjustment angle of 8 PD undercorrection for near would allow for postoperative drift and reduce the chances of a late overcorrection. This would require careful preoperative counseling of the patient in order to explain that immediate undercorrection and persistent diplopia were necessary in order to generate a better long-term result.

Is artificial reproductive technology a risk factor for retinopathy of prematurity independent of the generation of multiple births?

PURPOSE: There is some debate regarding whether artificial reproductive technology (ART) constitutes an independent risk factor for retinopathy of prematurity (ROP). We wanted to assess the prevalence of ART in multiple birth infants seen for ROP screening and whether or not ROP was identified or treated, in order to evaluate whether ART contributes a risk factor for ROP independent of the generation of multiple births. METHODS: A retrospective audit was performed of all multiple birth babies admitted to a tertiary neonatal unit who met the UK ROP screening criteria (<32 weeks gestational age [GA] and/or <1,501 g birthweight [BW]). RESULTS: A total of 205 babies met our criteria, of whom 87.3% were twins. A total of 39.5% were born following ART. A total of 30.5% of the non-ART group developed ROP vs 34% of the ART group (p = 0.837). Stage 3 ROP developed in 5.1% of non-ART babies and 6% of ART babies. A total of 8.5% of non-ART babies and 10% of ART babies required treatment for ROP. Logistic regression demonstrated that ART was not independently associated with development of ROP. CONCLUSIONS: Artificial reproductive technology multiple birth babies make up a considerable proportion of the ROP screening burden and their number is likely to increase as ART is increasingly available and utilized. We found no significant difference between the numbers of babies developing ROP in the ART vs non-ART groups, but the numbers are small. The estimated odds of developing ROP are slightly higher in the ART babies, so our data do not rule out a possible association.

Psychosocial interventions for improving quality of life outcomes in adults undergoing strabismus surgery.

BACKGROUND: Strabismus, also known as squint, can have a debilitating effect on a person's self-esteem, quality of life and mood, as well as increase their feelings of social anxiety and avoidance behaviour. Strabismus surgery can improve both the alignment of a person's eyes and, in appropriate cases, relieve symptoms such as double vision. However, evidence indicates that not all patients experience a meaningful improvement in their quality of life postsurgery. Pre-surgical psychosocial interventions have been found to improve patient reported outcomes in other long-term conditions. OBJECTIVES: To assess the effects of psychosocial interventions versus no intervention on quality of life and psychosocial outcomes in adults undergoing strabismus surgery. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision group Trials Register) (2016, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to February 2016), EMBASE (January 1980 to February 2016), Latin American and Caribbean Health Sciences (LILACS) (January 1982 to February 2016), PsycINFO (January 1967 to February 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 15 February 2016.We also manually searched the British Orthoptic Journal, proceedings of the European Strabismological Association (ESA), International Strabismological Association (ISA) and published transactions from the meetings of European Strabismus Association (ESA) and American Association for Pediatric Ophthalmology and Strabismus (AAPOS). These were searched from 1980 to present. We also carried out handsearches of Psychology and Health, British Journal of Health Psychology, Health Psychology and Annals of Behavioral Medicine. SELECTION CRITERIA: We planned to include randomised controlled trials (RCTs), including cluster-RCTs, in which effectiveness of a psychosocial intervention had been evaluated in patients due to undergo strabismus surgery. DATA COLLECTION AND ANALYSIS: Two review authors independently reviewed the search results for eligibility. MAIN RESULTS: None of the 88 studies we identified met the inclusion criteria of this Cochrane review. AUTHORS' CONCLUSIONS: We found no evidence that evaluated the impact of psychosocial interventions on patients undergoing squint surgery. We believe future research should focus on developing and evaluating the use of targeted psychosocial interventions to improve a patient's quality of life after strabismus surgery.

Description and evaluation of the first national patient and public involvement day for thyroid eye disease in the United Kingdom.

BACKGROUND: To ensure appropriate patient-focused outcomes, the National Institute for Health Research (NIHR) in the United Kingdom has made consultation with patients, caregivers, and the public a prerequisite to providing research funding. One method of encouraging engagement with research is through patient and public involvement (PPI) events. We describe the planning and implementation of a PPI day for thyroid eye disease (TED) and evaluate our own event using feedback from delegates. METHODS: The Moorfields NIHR Biomedical Research Centre, in partnership with TED charities, arranged the first national PPI day for TED in the United Kingdom. The event included didactic lectures; pre-event and postevent questionnaires; an exhibition with stalls, posters, and an interactive voting wall to determine research priorities; focus group sessions to explore patient experiences and perceptions of research; and one-on-one interviews recording individual patient stories. RESULTS: Of 100 attendees, 70 completed questionnaires. When asked whether the day had provided what they wanted, 48 of 52 (92%) said yes; 3 of 52 (6%) said no. Overall 6 of 52 (12%) rated the event as good; 28 of 52 (54%), very good; and 18 of 52 (34%), excellent. Thirty-six patients registered to participate in further research, identifying "finding the cause for TED," "improving psychological support," and "achieving a better cosmetic outcome" as key priorities. A poor understanding of TED among medical professionals was a common complaint. CONCLUSIONS: The event received positive feedback and achieved its key objective of engaging patients, researchers, and clinicians in a two-way discussion about research priorities and improved study design. An invaluable insight was gained into patients' needs for a better quality of life, and we have demonstrated that important data can be captured from such events, providing an evidential basis consistent with the NIHR principles of patient-centered research.

Latency can be conferred to a variety of cytokines by fusion with latency-associated peptide from TGF-ß.

OBJECTIVES: Targeting cytokines to sites of disease has clear advantages because it increases their therapeutic index. We designed fusion proteins of the latent-associated peptide (LAP) derived from TGF-ß with various cytokines via a matrix metalloproteinase (MMP) cleavage site. This design confers latency, increased half-life and targeting to sites of inflammation. The aim of this study is to determine whether this approach can be applied to cytokines of different molecular structures and sizes. METHODS: Mature cytokines cloned downstream of LAP and a MMP cleavage site were expressed in 293T cells and assessed for latency and biological activity by Western blotting and bioassay. RESULTS: We demonstrate here that fusion proteins of TGF-ß, erythropoietin, IL-1ra, IL-10, IL-4, BMP-7, IGF1 and IL-17 were rendered latent by fusion to LAP, requiring cleavage to become active in respective bioassays. As further proof of principle, we also show that delivery of engineered TGF-ß can inhibit experimental autoimmune encephalomyelitis and that this approach can be used to efficiently deliver cytokines to the brain and spinal cord in mice with this disease. CONCLUSIONS: The latent cytokine approach can be successfully applied to a range of molecules, including cytokines of different molecular structure and mass, growth factors and a cytokine antagonist.

Latent cytokines for targeted therapy of inflammatory disorders.

INTRODUCTION: The use of cytokines as therapeutic agents is important, given their potent biological effects. However, this very potency, coupled with the pleiotropic nature and short half-life of these molecules, has limited their therapeutic use. Strategies to increase the half-life and to decrease toxicity are necessary to allow effective treatment with these molecules. AREAS COVERED: A number of strategies are used to overcome the natural limitations of cytokines, including PEGylation, encapsulation in liposomes, fusion to targeting peptides or antibodies and latent cytokines. Latent cytokines are engineered using the latency-associated peptide of transforming growth factor-ß to produce therapeutic cytokines/peptides that are released only at the site of disease by cleavage with disease-induced matrix metalloproteinases. The principles underlying the latent cytokine technology are described and are compared to other methods of cytokine delivery. The potential of this technology for developing novel therapeutic strategies for the treatment of diseases with an inflammatory-mediated component is discussed. EXPERT OPINION: Methods of therapeutic cytokine delivery are addressed. The latent cytokine technology holds significant advantages over other methods of drug delivery by providing simultaneously increased half-life and localised drug delivery without systemic effects. Cytokines that failed clinical trials should be reassessed using this delivery system.

A comparative study of matrix metalloproteinase and aggrecanase mediated release of latent cytokines at arthritic joints.

BACKGROUND: Latent cytokines are engineered by fusing the latency associated peptide (LAP) derived from transforming growth factor-ß (TGF-ß) with the therapeutic cytokine, in this case interferon-ß (IFN-ß), via an inflammation-specific matrix metalloproteinase (MMP) cleavage site. OBJECTIVES: To demonstrate latency and specific delivery in vivo and to compare therapeutic efficacy of aggrecanase-mediated release of latent IFN-ß in arthritic joints to the original MMP-specific release. METHODS: Recombinant fusion proteins with MMP, aggrecanase or devoid of cleavage site were expressed in CHO cells, purified and characterised in vitro by Western blotting and anti-viral protection assays. Therapeutic efficacy and half-life were assessed in vivo using the mouse collagen-induced arthritis model (CIA) of rheumatoid arthritis and a model of acute paw inflammation, respectively. Transgenic mice with an IFN-regulated luciferase gene were used to assess latency in vivo and targeted delivery to sites of disease. RESULTS: Efficient localised delivery of IFN-ß to inflamed paws, with low levels of systemic delivery, was demonstrated in transgenic mice using latent IFN-ß. Engineering of latent IFN-ß with an aggrecanase-sensitive cleavage site resulted in efficient cleavage by ADAMTS-4, ADAMTS-5 and synovial fluid from arthritic patients, with an extended half-life similar to the MMP-specific molecule and greater therapeutic efficacy in the CIA model. CONCLUSIONS: Latent cytokines require cleavage in vivo for therapeutic efficacy, and they are delivered in a dose dependent fashion only to arthritic joints. The aggrecanase-specific cleavage site is a viable alternative to the MMP cleavage site for the targeting of latent cytokines to arthritic joints.

Increased disulphide dimer formation of latent associated peptide fusions of TGF-ß by addition of L-cystine.

The development of novel protein therapeutics relies on the ability to express appreciable amounts of correctly folded recombinant proteins. Latent IFN-ß is engineered using the latency-associated peptide (LAP) of transforming growth factor ß1 (TGF-ß1) to maintain IFN-ß in a biologically inactive form until such time as it is released at sites of inflammation by matrix metalloproteinase activity (see Adams et al., 2003). CHO cells cultured in suspension were used for expression of latent IFN-ß to allow medium scale transient transfection. However, the recombinant protein expressed in this system consisted of a mixture of properly linked disulphide dimers and monomers. The ratio of dimer:monomer produced could be significantly altered towards increased dimer production by the addition of L-cystine to the CHO culture medium. The total yield of latent IFN-ß was increased by co-transfection of plasmid coding for the simian virus (SV) 40 large T antigen to the plasmid with the SV40 origin of replication expressing latent IFN-ß DNA. These results provide valuable new insights for developing protocols to produce substantial quantities of latent cytokine dimers in CHO cells in suspension.

The effect on quality of life of long-term botulinum toxin A injections to maintain ocular alignment in adult patients with strabismus.

BACKGROUND: There is considerable evidence to show that strabismus patients report their quality of life (QoL) as lower than normal controls. While the majority of patients with strabismus are treated with surgery there are a number of cases where surgery is not possible and good long-term ocular alignment can be maintained with repeated injections of botulinum toxin. METHODS: 65 patients who had undergone over 25 injections of botulinum toxin A for long-term control of their deviation were identified and asked to fill in and return the Adult Strabismus questionnaire (AS-20) to assess their QoL. RESULTS: 46 questionnaires were available for analysis. The mean AS-20 score in our patients compared favourably with that reported for normal controls and was much higher than that reported for patients with strabismus. CONCLUSION: Long-term injections with botulinum toxin A is a good treatment for maintaining ocular alignment if squint surgery is not indicated and those patients receiving treatment score near the level of normal controls in QoL terms.

Molecular engineering of short half-life small peptides (VIP, αMSH and γ3MSH) fused to latency-associated peptide results in improved anti-inflammatory therapeutics.

OBJECTIVE: To facilitate the targeting to inflammation sites of small anti-inflammatory peptides, with short half-lives, by fusion with the latency-associated peptide (LAP) of transforming growth factor ß1 through a cleavable matrix metalloproteinase (MMP) linker. This design improves efficacy, overcoming the limitations to their clinical use. METHODS: We generated latent forms of vasoactive intestinal peptide (VIP), α-melanocyte-stimulating hormone (MSH) and γ(3)MSH by fusion to LAP through an MMP cleavage site using recombinant DNA technology. The biological activities of these latent therapeutics were studied in vivo using monosodium urate (MSU)-induced peritonitis and collagen-induced arthritis (CIA) models. We assessed gene therapy and purified protein therapy. RESULTS: The recruitment of the polymorphonuclear cells induced by MSU injection into mouse peritoneal cavity was reduced by 35% with γ(3)MSH (1 nmol), whereas administration of a much lower dose of purified latent LAP-MMP-γ(3)MSH (0.03 nmol) attenuated leucocyte influx by 50%. Intramuscular gene delivery of plasmids coding LAP-MMP-VIP and LAP-MMP-αMSH at disease onset reduced the development of CIA compared with LAP-MMP, which does not contain any therapeutic moiety. Histological analysis confirmed a significantly lower degree of inflammation, bone and cartilage erosion in groups treated with LAP-MMP-VIP or LAP-MMP-αMSH. Antibody titres to collagen type II and inflammatory cytokine production were also reduced in these two groups. CONCLUSION: Incorporation of small anti-inflammatory peptides within the LAP shell and delivered as recombinant protein or through gene therapy can control inflammatory and arthritic disease. This platform delivery can be developed to control human arthritides and other autoimmune diseases.

A newborn with unilateral limb enlargement.

On routine neonatal examination, a newborn term male was noted to have unilateral enlargement of the right lower limb, loose thickened red skin over the palm and widening of all the fingers on the right hand. His body was pinker and warmer on the right side compared with the left and he had a right undescended testicle and hypoplastic scrotum. Radiological examination of the lower limbs demonstrated the enlargement of the soft tissue of the right lower limb compared to the left (Fig. 1). Therefore, the diagnosis was unclear from this constellation of findings and an ophthalmic assessment was requested.

Alternate day exotropia.

INTRODUCTION: Cyclic strabismus is a rare disorder in which manifest strabismus and controlled latent deviation (heterophoria) alternates on a regular pattern which is usually over a 48-hr period. During the "straight" period the patient has a fully controlled heterophoria for all distances, with very good fusion and stereopsis. During the "squinting" period the patient has a constant manifest strabismus for all distances, with no demonstrable fusion and stereopsis. METHOD: We describe 2 cases of alternate day exotropia. One patient requires strabismus surgery to obtain constant binocularity. The second patient underwent surgery for an intermittent exotropia and subsequently developed an alternate day exotropia. The condition very gradually reduced over the years and the patient is now fully binocular. CONCLUSION: We report the first 2 cases of cyclic exotropia in non-Japanese female children presenting from about 1 to 3 years of age, without ocular or systemic pathology.

Mutation in Rab3 GTPase-activating protein (RAB3GAP) noncatalytic subunit in a kindred with Martsolf syndrome.

We identified a homozygous missense mutation in the noncatalytic subunit (RAB3GAP2) of RAB3GAP that results in abnormal splicing in a family with congenital cataracts, hypogonadism, and mild mental retardation (Martsolf syndrome). Recently, mutations in the catalytic subunit of RAB3GAP (RAB3GAP1), a key regulator of calcium-mediated hormone and neurotransmitter exocytosis, were reported in Warburg micro syndrome, a severe neurodevelopmental condition with overlapping clinical features. RAB3GAP is a heterodimeric protein that consists of a catalytic subunit and a noncatalytic subunit encoded by RAB3GAP1 and RAB3GAP2, respectively. We performed messenger RNA-expression studies of RAB3GAP1 and RAB3GAP2 orthologues in Danio rerio embryos and demonstrated that, whereas developmental expression of rab3gap1 was generalized (similar to that reported elsewhere in mice), rab3gap2 expression was restricted to the central nervous system. These findings are consistent with RAB3GAP2 having a key role in neurodevelopment and may indicate that Warburg micro and Martsolf syndromes represent a spectrum of disorders. However, we did not detect RAB3GAP2 mutations in patients with Warburg micro syndrome. These findings suggest that RAB3GAP dysregulation may result in a spectrum of phenotypes that range from Warburg micro syndrome to Martsolf syndrome.

Methods for targeting biologicals to specific disease sites.

Cytokines are mediators of cell communication. Their therapeutic use requires frequent high doses to achieve effective local biological levels. However, the clinical use of some cytokines is limited because of their pleiotropism, which can result in unwanted side effects. Here, we review novel protein engineering technologies that overcome these limitations and enable the targeting of cytokines to specific sites. One such technology uses antibody-based recognition to direct the cytokine to a particular tissue, and another creates encapsulated latent cytokines that are released only at the site of disease. The latter method requires the overexpression of matrix-metalloproteinases, thereby exploiting the severity of the pathological process to regulate drug delivery. Because these technologies are based on the expression of fusion proteins, their application can be extended to other biologicals and can be delivered by gene therapy.

Latent cytokines: development of novel cleavage sites and kinetic analysis of their differential sensitivity to MMP-1 and MMP-3.

We have engineered a latent mouse interferon beta (mIFNbeta) using the latency associated peptide (LAP) of transforming growth factor beta1 (TGF-beta1) to protect the cytokine and avoid its interaction with its receptors. This approach improves the pharmacokinetic properties and reduces the pleiotropic effects limiting the current therapeutic use of cytokines. IFNbeta was fused to the LAP using two flexible linkers flanking a matrix metalloproteinase (MMP) cleavage site for the specific release of IFNbeta at disease sites. In order to improve the hydrolysis rate of the cleavage site, 15 different cleavable linkers were introduced in the LAP-mIFNbeta construct. The kinetic parameters relative to the linker cleavage by MMP-1 and MMP-3 were measured by an ELISA method. Among the modifications done, one of the constructs bearing the activation site of pro-MMPs was the best substrate for both enzymes. The introduction of a hydrophilic sequence derived from the furin cleavage site of the anthrax toxin protective antigen increased the sensitivity to MMP-3 to up to 29-fold. These data suggest that this strategy could be useful for improving the effectiveness of the delivery and targeting of protein therapeutics.

Targeting therapeutic molecules to sites of disease.

Extract: The holy grail of drug development is to design a magic bullet that will deliver a therapeutic agent only to the site of disease with minimal side effects. This is of great importance in particular when it refers to biological agents such as cytokines that have pleiotropic actions in different tissues. Cytokines are local mediators of cell-to-cell communication. Their expression is transient and they have a short half-life. Therefore, to overcome the pharmacokinetic limitations of cytokines, they are given subcutaneously to reduce side effects. However, by this route they lose their potency. In order to use cytokines for therapeutic purposes they have to be administered frequently at high doses to achieve biologically active concentrations locally at the required sites of a disease.