Polymers for Disrupting Protein-Protein Interactions: Where Are We and Where Should We Be?

Protein-protein interactions (PPIs) are central to the cellular signaling and regulatory networks that underlie many physiological and pathophysiological processes. It is challenging to target PPIs using traditional small molecule or peptide-based approaches due to the frequent lack of well-defined binding pockets at the large and flat PPI interfaces. Synthetic polymers offer an opportunity to circumvent these challenges by providing unparalleled flexibility in tuning their physiochemical properties to achieve the desired binding properties. In this review, we summarize the current state of the field pertaining to polymer-protein interactions in solution, highlighting various polyelectrolyte systems, their tunable parameters, and their characterization. We provide an outlook on how these architectures can be improved by incorporating sequence control, foldability, and machine learning to mimic proteins at every structural level. Advances in these directions will enable the design of more specific protein-binding polymers and provide an effective strategy for targeting dynamic proteins, such as intrinsically disordered proteins.

Localized calcium oxalate crystals in primary cutaneous aspergillosis.

Select Aspergillus species can produce oxalate as a fermentation byproduct, which may react with calcium ions to produce insoluble calcium oxalate crystals in tissues. These crystals are frequently associated with pulmonary Aspergillus infections, yet are rarely described in primary cutaneous aspergillosis. Herein, we report the presence of calcium oxalate crystals detected on cutaneous specimens from primary cutaneous Aspergillus niger and Aspergillus fumigatus infections in an immunocompromised, premature infant. No metabolic sources of oxalosis were found.

A review of topical probiotic therapy for atopic dermatitis.

Atopic dermatitis (AD) is a common, chronic skin disorder that is associated with dysbiosis of the skin microbiome along with an impaired skin barrier and abnormal immune signalling. Particularly, AD has been associated with increased abundance of Staphylococcus aureus and decreased overall bacterial diversity. Topical probiotic formulations are garnering further interest in the treatment of AD and may be derived from commensal bacteria found on healthy epithelium or from exogenous bacteria. Strains chosen for clinical trials have often demonstrated antimicrobial actions to S. aureus in vitro. Multiple randomized clinical trials with topical probiotics have resulted in significant improvements in clinical severity, decreased abundance of S. aureus in treated lesional skin and increased bacterial diversity. Side-effects from available studies have been minimal apart from one patient who developed a furuncle in the treatment area. Topical probiotics have been shown to be safe and potentially efficacious in AD; however, further research including larger, longer-term clinical trials need to be performed before topical probiotics should be recommended to patients.

Mitochondria in neurogenesis: Implications for mitochondrial diseases.

Mitochondria are organelles with recognized key roles in cellular homeostasis, including bioenergetics, redox, calcium signaling, and cell death. Mitochondria are essential for neuronal function, given the high energy demands of the human brain. Consequently, mitochondrial diseases affecting oxidative phosphorylation (OXPHOS) commonly exhibit neurological impairment. Emerging evidence suggests that mitochondria are important not only for mature postmitotic neurons but also for the regulation of neural progenitor cells (NPCs) during the process of neurogenesis. These recent findings put mitochondria as central regulator of cell fate decisions during brain development. OXPHOS mutations may disrupt the function of NPCs and thereby impair the metabolic programming required for neural fate commitment. Promoting the mitochondrial function of NPCs could therefore represent a novel interventional approach against incurable mitochondrial diseases.

Real-world utilization of Delphi consensus diagnostic criteria for suspected pyoderma gangrenosum.

We found that the systematic use of Delphi consensus diagnostic criteria resulted in substantial changes in management patterns in cases of suspected pyoderma gangrenosum (PG), including a reduction in systemic corticosteroid use, and significantly improved clinical outcomes. This improvement may have resulted from a combination of reduced misdiagnosis, optimized management and reduced iatrogenic harm. Increased utilization of validated diagnostic criteria for PG could optimize provider heuristics, increase diagnostic accuracy, and optimize management and clinical outcomes.

Tunable hydrogels for mesenchymal stem cell delivery: Integrin-induced transcriptome alterations and hydrogel optimization for human wound healing.

Therapeutic applications for mesenchymal stem/stromal cells (MSCs) are growing; however, the successful implementation of these therapies requires the development of appropriate MSC delivery systems. Hydrogels are ideally suited to cultivate MSCs but tuning hydrogel properties to match their specific in vivo applications remains a challenge. Thus, further characterization of how hydrogel-based delivery vehicles broadly influence MSC function and fate will help lead to the next generation of more intelligently designed delivery vehicles. To date, few attempts have been made to comprehensively characterize hydrogel impact on the MSC transcriptome. Herein, we have synthesized cell-degradable hydrogels based on bio-inert poly(ethylene glycol) tethered with specific integrin-binding small molecules and have characterized their resulting effect on the MSC transcriptome when compared with 2D cultured and untethered 3D hydrogel cultured MSCs. The 3D culture systems resulted in alterations in the MSC transcriptome, as is evident by the differential expression of genes related to extracellular matrix production, glycosylation, metabolism, signal transduction, gene epigenetic regulation, and development. For example, genes important for osteogenic differentiation were upregulated in 3D hydrogel cultures, and the expression of these genes could be partially suppressed by tethering an integrin-binding RGD peptide within the hydrogel. Highlighting the utility of tunable hydrogels, when applied to ex vivo human wounds the RGD-tethered hydrogel was able to support wound re-epithelialization, possibly due to its ability to increase PDGF expression and decrease IL-6 expression. These results will aid in future hydrogel design for a broad range of applications.

Psychosocial and psychiatric comorbidities and health-related quality of life in alopecia areata: A systematic review.

BACKGROUND: Alopecia areata (AA) is an immune-mediated disease resulting in nonscarring hair loss. Systematic reviews on the psychosocial and psychiatric comorbidities, health-related quality of life, and interventions targeting psychosocial well-being are limited. OBJECTIVE: To conduct a systematic review of the psychosocial comorbidities, health-related quality of life, and treatment options targeting psychosocial well-being in adult and pediatric AA patients. METHODS: A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines within the PubMed database. Specific search terms included, but were not limited to, alopecia areata, psychosocial, psychiatry, and quality of life. Studies were then evaluated for their design and categorized into corresponding levels of evidence according to the guidelines adapted from the Oxford Center for Evidence Based Medicine. FINDINGS: Seventy-three reports met inclusion criteria, involving approximately 414,319 unique participants. AA patients were found to have psychiatric comorbidities, particularly anxiety and depression. Health-related quality of life is reduced in AA patients, but data on pediatric AA quality of life are limited. Psychotherapy is often recommended as adjuvant treatment. CONCLUSION: AA has substantial psychosocial impact on patients and results in reduced health-related quality of life. Addressing this should be an active part of treatment.

Enzyme Catalysis in Non-Native Environment with Unnatural Selectivity Using Polymeric Nanoreactors.

The utilization of enzymes for catalysis in organic solvents, while exhibiting selectivity to different substrates, is a big challenge. We report an amphiphilic random copolymer system that self-assembles with enzymes in an organic solvent to form nanoreactors. These encapsulated enzymes are not denatured and they do preserve the catalytic activity. The cross-linkable functional groups in the hydrophobic compartments of the polymers offer to control accessibility to the enzyme. This varied accessibility due to the polymer host, rather than the enzyme itself, endows the nanoreactor with an unnatural selectivity. The findings here highlight the significant potential of simple polymer-based enzyme nanoreactors to execute selective organic reactions under non-native conditions.

Updated therapies for the management of Psoriatic Arthritis.

Psoriatic arthritis (PsA) is a large volume of our clinical practice and its management can be challenging. Traditional DMARDs have been used over last six decades and observational studies have substantiated an effective use of many of these drugs. However, in last two decades use of anti-TNF agents has brought a new dimension in treatment of PsA and in many other autoimmune diseases. Regulatory role of the Th17 cells and its cytokines in the pathogenesis of PsA has successfully paved the foundations of anti-IL antibody based therapies in PsA. Newer therapies targeting the IL-23/IL-17 cytokines and its signaling proteins are now in development and bringing new promises for management of PsA. Herein, we provide an overview of the landscape of drug therapies, including IL-17, IL-12/23, IL-23 inhibitors, and janus kinase (JAK) inhibitors, as well as those in development, such as RORγt inhibitors, anti-NGF agents, mTOR inhibitors and T cell ion-channel blockers.

The cutaneous and intestinal microbiome in psoriatic disease.

Psoriasis (PsO) and psoriatic arthritis (PsA) are chronic immune-mediated inflammatory diseases of multifactorial etiology. In addition to genetic and environmental factors, evidence supports involvement of a dysregulated human microbiome in the pathogenesis of psoriatic disease. In particular, alterations in the composition of the microbiome, termed dysbiosis, can result in downstream proinflammatory effects in the gut, skin, and joints. Both the cutaneous and intestinal microbial populations are implicated in the pathogenesis of psoriatic disease, although exact mechanisms are unclear. Herein, we review the relationship between the human microbiome and psoriatic disease. Further insight into the functions of the microbiome may allow for greater understanding of inflammatory disease processes and identification of additional therapeutic targets.

Successful Management of Anti-TNF-Induced Psoriasis Despite Continuation of Therapy in a Pyoderma Gangrenosum Patient

Pyoderma gangrenosum is an inflammatory, neutrophil-mediated disorder that is difficult to treat. Tumor necrosis factor and other inflammatory mediators are among the most promising therapeutic targets. We present a case of a 60-year-old woman with recalcitrant pyoderma gangrenosum treated with adalimumab, who paradoxically developed psoriasis. Secukinumab, an interleukin-17 inhibitor, was added to her regimen, resulting in successful treatment of her psoriasis. Secukinumab was later replaced by methotrexate, resulting in remission of both pyoderma gangrenosum and maintenance of a psoriasis-free state. We conclude that paradoxically induced psoriatic lesions can resolve with adjunct therapy despite continuation of anti-tumor necrosis factor agents. J Drugs Dermatol. 2020;19(2)199-201. doi:10.36849/JDD.2020.4662

Nummular dermatitis on guselkumab for palmoplantar psoriasis.

A 40-year-old man with chronic history of refractory palmoplantar psoriasis presented with new onset of well-demarcated oval erythematous asteatotic plaques on bilateral shins after starting guselkumab therapy. Histopathology revealed chronic spongiotic dermatitis consistent with a diagnosis of nummular dermatitis. This case highlights a previously unreported adverse event to guselkumab therapy.

Umbilical condyloma lata.

Condyloma lata, a cutaneous manifestation of secondary syphilis, usually appear as verrucous papules and plaques in the anogenital area. Involvement of the umbilicus is very uncommon. Thus, awareness of this presentation, along with appropriate history, physical exam, and laboratory testing may aid clinicians in prompt and accurate diagnosis. We describe a patient with an unusual presentation of condyloma lata on the umbilicus.

Eosinophilic fasciitis presenting as a unilateral, solitary plaque.

Eosinophilic fasciitis is a rare connective tissue disorder characterized by inflammation of the fascia that leads to painful, indurated skin. Because of its variable clinical presentation and overlap with conditions, such as morphea, the diagnosis of eosinophilic fasciitis can be challenging and relies on clinical presentation, histopathologic and laboratory analysis, and response to therapy. Herein, we present an unusual, solitary, isolated plaque with pathologic features and response to therapy most consistent with eosinophilic fasciitis.

End stage scurvy in the developed world: A diagnostic conundrum but not to be mistaken for pyoderma gangrenosum.

Scurvy is a clinical syndrome, resulting from ascorbic acid deficiency. Prevalence of the condition is now extremely low in the Western population and its diagnosis can be challenging without a high index of suspicion. When cases do present, they are often misdiagnosed initially. Therefore, a thorough history, physical exam, and laboratory evaluation are key to showing this now rare but extremely well-known disease. We report a case of scurvy manifesting as persistent non-healing lower-extremity ulcerations, initially mistaken for pyoderma gangrenosum. The patient responded to appropriate replacement therapy, but ulcers were slow to heal. As was the case in our patient, symptom reversal may require additional nutritional replacement. We encourage physicians to consider nutritional deficiencies in their differential diagnoses and highlight the incidence of malnutrition in the proper clinical setting to avoid diagnostic delay.

Mohs micrographic surgery for cutaneous malignancies: A focus review of its indications in pediatric age groups.

Mohs micrographic surgery (MMS) is a highly specialized technique that has been successful in the treatment of a variety of skin tumors. The technique can be performed as an outpatient procedure and encompasses surgical excision and intraoperative assessment of tumor margins in one setting by the same physician. The process ensures precise margin control with maximal preservation of healthy tissues. Mohs micrographic surgery has been practiced worldwide, including in the United States, Europe (United Kingdom, Germany, Spain, Netherlands, Switzerland), and Australia. Although it is commonly performed in adults with greater success, it has been discussed less frequently in children. In this article, we describe several cutaneous tumors in children and the role of Mohs micrographic surgery in their management. A PubMed search was conducted to review the most common cutaneous tumors in children treated using Mohs micrographic surgery. In this review, we discuss indications for Mohs micrographic surgery and pertinent studies examining success rates in children. Mohs micrographic surgery has been used to treat several tumors in children and offers the advantage of high cure rates and tissue conservation. This report emphasizes the benefits of Mohs micrographic surgery in children and highlights several cutaneous tumors for which it has been used to treat successfully.

X-ray Crystallographic Structure of a Giant Double-Walled Peptide Nanotube Formed by a Macrocyclic ß-Sheet Containing Aß16-22.

This paper describes the supramolecular assembly of a macrocyclic ß-sheet containing residues 16-22 of the ß-amyloid peptide, Aß. X-ray crystallography reveals that the macrocyclic ß-sheet assembles to form double-walled nanotubes, with an inner diameter of 7 nm and outer diameter of 11 nm. The inner wall is composed of an extended network of hydrogen-bonded dimers. The outer wall is composed of a separate extended network of ß-barrel-like tetramers. These large peptide nanotubes pack into a hexagonal lattice that resembles a honeycomb. The complexity and size of the peptide nanotubes rivals some of the largest tubular biomolecular assemblies, such as GroEL and microtubules. These observations demonstrate that small amyloidogenic sequences can be used to build large nanostructures.