Biogeographic and disease-specific alterations in epidermal lipid composition and single cell analysis of acral keratinocytes

The epidermis is the outermost layer of skin. Here, we used targeted lipid profiling to characterize the biogeographic alterations of human epidermal lipids across 12 anatomically distinct body sites, and we used single-cell RNA-Seq to compare keratinocyte gene expression at acral and nonacral sites. We demonstrate that acral skin has low expression of EOS acyl-ceramides and the genes involved in their synthesis, as well as low expression of genes involved in filaggrin and keratin citrullination (PADI1 and PADI3) and corneodesmosome degradation, changes that are consistent with increased corneocyte retention. Several overarching principles governing epidermal lipid expression were also noted. For example, there was a strong negative correlation between the expression of 18-carbon and 22-carbon sphingoid base ceramides. Disease-specific alterations in epidermal lipid gene expression and their corresponding alterations to the epidermal lipidome were characterized. Lipid biomarkers with diagnostic utility for inflammatory and precancerous conditions were identified, and a 2-analyte diagnostic model of psoriasis was constructed using a step-forward algorithm. Finally, gene coexpression analysis revealed a strong connection between lipid and immune gene expression. This work highlights (a) mechanisms by which the epidermis is uniquely adapted for the specific environmental insults encountered at different body surfaces and (b) how inflammation-associated alterations in gene expression affect the epidermal lipidome.

Community investment interventions as a means for decarceration: A scoping review

There is growing support to reverse mass incarceration in the United States, especially in the wake of the COVID-19 pandemic. Little is known about what types and scale of community investments are most effective to support mass decarceration. Using a public health prevention framework, we conducted a scoping review to examine community-based programs that reduced criminal legal involvement. We searched PubMed, Embase and three EBSCO databases from 1990 through September 2019 for all experimental or quasi-experimental studies testing interventions pertaining to education, housing, healthcare, employment, or social support services and how they affected an individual's criminal legal outcomes. Our review identified 53 studies that demonstrated the efficacy of early childhood educational interventions and nurse-family partnership programs, post-secondary education for incarcerated students, navigation programs linking incarcerated people to community resources, and peer support upon release to reduce criminal legal system exposure. In concert with legislative action to end mass incarceration, additional research is needed to test interventions designed to achieve mass decarceration which cross multiple domains, interrogate community-level impacts and ascertain long-term outcomes.

Immune profiling of lupus miliaris disseminatus faciei and successful management with anti-tumour necrosis factor therapy

Lupus miliaris disseminatus faciei (LMDF) is a chronic inflammatory dermatosis of unknown aetiology, most often seen in young adults. Although many treatments for LMDF exist, treatment guidelines have not been developed, and response to therapy is generally unpredictable. We present the results of transcriptomic analysis of LMDF lesional skin, which revealed a variety of differentially expressed genes linking LMDF to alterations in innate and adaptive T helper 1 immunity. Immunohistochemical analysis was also performed, identifying similar changes in T-cell immune responses. Given evidence for increased tumour necrosis factor (TNF) pathway activity, our patient, who had previously been refractory to multiple treatments, was initiated on TNF inhibitor therapy with excellent response. This characterization of the LMDF immune response may lead to improved treatment of this condition.

Multiple Growth Factor Targeting by Engineered Insulin-like Growth Factor Binding Protein-3 Augments EGF Receptor Tyrosine Kinase Inhibitor Efficacy

Resistance to cancer therapy is a challenge because of innate tumor heterogeneity and constant tumor evolution. Since the pathway of resistance cannot be predicted, combination therapies may address this progression. We discovered that in addition to IGF1 and IGF2, IGFBP-3 binds bFGF, HGF, neuregulin, and PDGF AB with nanomolar affinity. Because growth factors drive resistance, simultaneous inhibition of multiple growth factor pathways may improve the efficacy of precision therapy. Growth factor sequestration by IGFBP-3-Fc enhances the activity of EGFR inhibitors by decreasing cell survival and inhibiting bFGF, HGF, and IGF1 growth factor rescue and also potentiates the activity of other cancer drugs. Inhibition of tumor growth in vivo with adjuvant IGFBP-3-Fc with erlotinib versus erlotinib after treatment cessation supports that the combination reduces cell survival. Inhibition of multiple growth factor pathways may postpone resistance and extend progression-free survival in many cancer indications.

Non-surgical management of primary invasive melanoma

Surgical excision is standard-of-care for primary invasive melanoma, but best care can be unclear for patients who are surgically high-risk or for whom resection may be excessively morbid. Alternatives to surgical excision have emerged for treatment of metastatic melanoma but have not yet been explored for primary invasive melanoma. Two elderly patients with primary invasive melanoma with many medical co-morbidities who were not surgical candidates were determined to be appropriate candidates for an intralesional IL-2 based regimen. Herein we report their clinical and histological outcome. An intralesional-based regimen (intralesional IL-2, topical imiquimod cream 5%, and tretinoin cream 0.1% under occlusion to the treatment site) was administered over the course of six to seven weeks, followed by two weeks of topical-only therapy. A complete response was seen after eight to nine weeks of treating invasive melanomas that were ≥1.85 mm and 5.5 mm thick. For patients with primary invasive melanoma on high morbidity sites and patients who are poor surgical candidates, a neoadjuvant intralesional IL-2-based approach may be a reasonable alternative. The two cases presented here suggest that alternative intralesional-based treatment modalities may minimize the size of the excision site and can be associated with complete histological clearance of invasive melanoma.

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.

Effectiveness of Online vs In-Person Care for Adults With Psoriasis: A Randomized Clinical Trial

IMPORTANCE

Innovative, online models of specialty-care delivery are critical to improving patient access and outcomes.

OBJECTIVE

To determine whether an online, collaborative connected-health model results in equivalent clinical improvements in psoriasis compared with in-person care.

DESIGN, SETTING, AND PARTICIPANTS

The Patient-Centered Outcomes Research Institute Psoriasis Teledermatology Trial is a 12-month, pragmatic, randomized clinical equivalency trial to evaluate the effect of an online model for psoriasis compared with in-person care. Participant recruitment and study visits took place at multicenter ambulatory clinics from February 2, 2015, to August 18, 2017. Participants were adults with psoriasis in Northern California, Southern California, and Colorado. The eligibility criteria were an age of 18 years or older, having physician-diagnosed psoriasis, access to the internet and a digital camera or mobile phone with a camera, and having a primary care physician. Analyses were on an intention-to-treat basis.

INTERVENTIONS

Participants were randomized 1:1 to receive online or in-person care (148 randomized to online care and 148 randomized to in-person care). The online model enabled patients and primary care physicians to access dermatologists online asynchronously. The dermatologists provided assessments, recommendations, education, and prescriptions online. The in-person group sought care in person. The frequency of online or in-person visits was determined by medical necessity. All participants were exposed to their respective interventions for 12 months.

MAIN OUTCOMES AND MEASURES

The prespecified primary outcome was the difference in improvement in the self-administered Psoriasis Area and Severity Index (PASI) score between the online and in-person groups. Prespecified secondary outcomes included body surface area (BSA) affected by psoriasis and the patient global assessment score.

RESULTS

Of the 296 randomized participants, 147 were women, 149 were men, 187 were white, and the mean (SD) age was 49 (14) years. The adjusted difference between the online and in-person groups in the mean change in the self-administered PASI score during the 12-month study period was -0.27 (95% CI, -0.85 to 0.31). The difference in the mean change in BSA affected by psoriasis between the 2 groups was -0.05% (95% CI, -1.58% to 1.48%). Between-group differences in the PASI score and BSA were within prespecified equivalence margins, which demonstrated equivalence between the 2 interventions. The difference in the mean change in the patient global assessment score between the 2 groups was -0.11 (95% CI, -0.32 to 0.10), which exceeded the equivalence margin, with the online group displaying greater improvement.

CONCLUSIONS AND RELEVANCE

The online, collaborative connected-health model was as effective as in-person management in improving clinical outcomes among patients with psoriasis. Innovative telehealth delivery models that emphasize collaboration, quality, and efficiency can be transformative to improving patient-centered outcomes in chronic diseases.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02358135.

Meta-analysis of RNA sequencing datasets reveals an association between TRAJ23, psoriasis, and IL-17A

Numerous studies of relatively few patients have linked T cell receptor (TCR) genes to psoriasis but have yielded dramatically conflicting results. To resolve these discrepancies, we have chosen to mine RNA-Seq datasets for patterns of TCR gene segment usage in psoriasis. A meta-analysis of 3 existing and 1 unpublished datasets revealed a statistically significant link between the relative expression of TRAJ23 and psoriasis and the psoriasis-associated cytokine IL-17A. TRGV5, a TCR-γ segment, was also associated with psoriasis but correlated instead with IL-36A, other IL-36 family members, and IL-17C (not IL-17A). In contrast, TRAJ39 was strongly associated with healthy skin. T cell diversity measurements and analysis of CDR3 sequences were also conducted, revealing no psoriasis-associated public CDR3 sequences. Finally, in comparison with the expression of TCR-αβ genes, the expression of TCR-γδ genes was relatively low but mildly elevated in psoriatic skin. These results have implications for the development of targeted therapies for psoriasis and other autoimmune diseases. Also, the techniques employed in this study have applications in other fields, such as cancer immunology and infectious disease.

A rare presentation of congenital syphilis: Pemphigus syphiliticus in a newborn infant with extensive desquamation of the extremities

Congenital syphilis is an infection transmitted from mother to fetus and can present with early but variable cutaneous manifestations. In rare situations, a bullous eruption known as pemphigus syphiliticus may develop. We present an unusual case of broad desquamation of the extremities in a newborn infant who was found to have congenital syphilis. Pemphigus syphiliticus should be considered in the differential diagnosis of neonatal bullous eruptions and erosions.

Classic Ulcerative Pyoderma Gangrenosum Is a T Cell-Mediated Disease Targeting Follicular Adnexal Structures: A Hypothesis Based on Molecular and Clinicopathologic Studies

Background

Pyoderma gangrenosum (PG) is a debilitating ulcerative skin disease that is one of the most common associated diseases seen in patients with inflammatory bowel disease and rheumatoid arthritis. Although PG is classified as a neutrophilic dermatosis, its pathophysiology is poorly understood.

Objective

Use data obtained from patient-reported histories, immunohistochemistry, and gene expression analysis to formulate a hypothesis on PG pathophysiology.

Methods

Ten PG patients participated and answered questions about new ulcer formation. Skin biopsies of healed prior ulcers and adjacent normal skin were obtained from four patients for immunohistochemistry. Scars from healthy patients and patients with discoid lupus were used as additional controls. New onset PG papules were analyzed using immunohistochemistry and gene expression analysis via quantitative real-time PCR.

Results

All PG patients reported that healed sites of previous ulceration are refractory to re-ulceration. Simultaneous biopsies of healed and uninvolved skin triggered ulceration only in the latter. On immunohistochemistry, healed PG scars showed complete loss of pilosebaceous units, which were present in normal skin, and to a lesser extent in control scars, and discoid scars. Early PG papules showed perivascular and peripilosebaceous T cell infiltrates, rather than neutrophils. These early inflammatory events were dominated by increased gene expression of CXCL9, CXCL10, CXCL11, IL-8, IL-17, IFNG, and IL-36G and transcription factors consistent with Th1 phenotype.

Limitations

Small sample size was the main limitation.

Conclusion

We put forth the hypothesis that PG is a T cell response resulting in the destruction of pilosebaceous units.

Targeting IL-17 in psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic and progressive inflammatory arthritis intimately associated with psoriasis, and can be an impairing disease that leads to reduced quality of life and significant morbidity. Treatment often requires TNF antagonists, yet many patients with PsA are not responsive to the standard anti-TNF therapies. The interleukin-17 (IL-17)/IL-17 receptor (IL-17R) family has recently been implicated in the pathogenesis of PsA and psoriasis. Much enthusiasm has been generated for the development of biologics that target the IL-17 signaling pathway directly or indirectly, many of which have produced striking results in the setting of psoriasis and PsA. Herein, we review the role of IL-17 and the IL-17 receptor (IL-17R) in the pathogenesis of PsA, as well as the clinical evidence for IL-17 and IL-17R targeted therapeutics.

Using qualitative methods to understand factors contributing to patient satisfaction among dermatology patients: a systematic review

PURPOSE

In this systematic review, we aimed to synthesize data that identify factors contributing to patient satisfaction in dermatology care using qualitative methods.

MATERIALS AND METHODS

We performed a comprehensive search of the literature using the PubMed database for articles published between January 1, 2000 and February 9, 2015. The initial search yielded 186 articles, of which 13 were included after applying inclusion and exclusion criteria.

RESULTS

The systematic review of 13 articles included a total of 330 patients. Using in-field observations and semistructured interviews, studies found that qualitative methods and analysis increased the provider's sensitivity to patient needs and enhanced patient care. Analyses using qualitative methods found increased patient satisfaction in their healthcare provider is associated with (1) confidence in the provider's diagnosis, (2) perception of patient-centered, individualized recommendations and (3) quality of patient education and provider explanation during a visit.

CONCLUSIONS

Patient satisfaction is measured using either quantitative or qualitative methods. Quantitative methods result in standardized data that often does not capture the nuances of patient experience. In contrast, qualitative methodology is integral to gathering patient perspectives on patient care and satisfaction and should be included in future research models.

Severe pellagra masked by concurrent plaque psoriasis: a case report of a hidden diagnosis

Despite characteristic features, psoriasis can mimic other dermatologic conditions, such as seborrheic dermatitis, lichen simplex chronicus, and certain nutritional deficiencies such as pellagra. We present a patient with a longstanding history of severe plaque psoriasis who presented with disfiguring scaly plaques involving greater than 80% body surface area. The patient's disease was minimally responsive to multiple therapies. Repeat punch biopsies demonstrated parakeratosis, psoriasiform hyperplasia, and dilated blood vessels consistent with psoriasis. Given atypical clinical features and overall poor treatment response additional work up was obtained. A serum nutritional panel was consistent with niacin deficiency and the patient later revealed extensive alcohol intake. A diagnosis of concurrent pellagra was made and the patient was started on niacin supplementation and instructed to reduce alcohol intake, while continuing adalimumab and high potency topical steroids. Within two weeks, his disease had markedly improved. Pellagra presents characteristically with a photosensitivity dermatitis that may appear clinically and histologically similar to psoriasis. It is important to maintain an index of suspicion for a secondary pathology in treatment-resistant psoriasis.

Sex-Specific Life Course Changes in the Neuro-Metabolic Phenotype of Glut3 Null Heterozygous Mice: Ketogenic Diet Ameliorates Electroencephalographic Seizures and Improves Sociability

We tested the hypothesis that exposure of glut3+/- mice to a ketogenic diet ameliorates autism-like features, which include aberrant behavior and electrographic seizures. We first investigated the life course sex-specific changes in basal plasma-cerebrospinal fluid (CSF)-brain metabolic profile, brain glucose transport/uptake, glucose and monocarboxylate transporter proteins, and adenosine triphosphate (ATP) in the presence or absence of systemic insulin administration. Glut3+/- male but not female mice (5 months of age) displayed reduced CSF glucose/lactate concentrations with no change in brain Glut1, Mct2, glucose uptake or ATP. Exogenous insulin-induced hypoglycemia increased brain glucose uptake in glut3+/- males alone. Higher plasma-CSF ketones (β-hydroxybutyrate) and lower brain Glut3 in females vs males proved protective in the former while enhancing vulnerability in the latter. As a consequence, increased synaptic proteins (neuroligin4 and SAPAP1) with spontaneous excitatory postsynaptic activity subsequently reduced hippocampal glucose content and increased brain amyloid β1-40 deposition in an age-dependent manner in glut3+/- males but not females (4 to 24 months of age). We then explored the protective effect of a ketogenic diet on ultrasonic vocalization, sociability, spatial learning and memory, and electroencephalogram seizures in male mice (7 days to 6 to 8 months of age) alone. A ketogenic diet partially restored sociability without affecting perturbed vocalization, spatial learning and memory, and reduced seizure events. We conclude that (1) sex-specific and age-dependent perturbations underlie the phenotype of glut3+/- mice, and (2) a ketogenic diet ameliorates seizures caused by increased cortical excitation and improves sociability, but fails to rescue vocalization and cognitive deficits in glut3+/- male mice.

CD4+ virtual memory: Antigen-inexperienced T cells reside in the naïve, regulatory, and memory T cell compartments at similar frequencies, implications for autoimmunity

It is widely accepted that central and effector memory CD4⁺ T cells originate from naïve T cells after they have encountered their cognate antigen in the setting of appropriate co-stimulation. However, if this were true the diversity of T cell receptor (TCR) sequences within the naïve T cell compartment should be far greater than that of the memory T cell compartment, which is not supported by TCR sequencing data. Here we demonstrate that aged mice with far fewer naïve T cells, respond to the model antigen, hen eggwhite lysozyme (HEL), by utilizing the same TCR sequence as their younger counterparts. CD4⁺ T cell repertoire analysis of highly purified T cell populations from naive animals revealed that the HEL-specific clones displayed effector and central "memory" cell surface phenotypes even prior to having encountered their cognate antigen. Furthermore, HEL-inexperienced CD4⁺ T cells were found to reside within the naïve, regulatory, central memory, and effector memory T cell populations at similar frequencies and the majority of the CD4⁺ T cells within the regulatory and memory populations were unexpanded. These findings support a new paradigm for CD4⁺ T cell maturation in which a specific clone can undergo a differentiation process to exhibit a "memory" or regulatory phenotype without having undergone a clonal expansion event. It also demonstrates that a foreign-specific T cell is just as likely to reside within the regulatory T cell compartment as it would the naïve compartment, arguing against the specificity of the regulatory T cell compartment being skewed towards self-reactive T cell clones. Finally, we demonstrate that the same set of foreign and autoreactive CD4⁺ T cell clones are repetitively generated throughout adulthood. The latter observation argues against T cell-depleting strategies or autologous stem cell transplantation as therapies for autoimmunity-as the immune system has the ability to regenerate pathogenic clones.

Functional Differences Between Direct and Indirect Striatal Output Pathways in Huntington's Disease

There is morphological evidence for differential alterations in striatal medium-sized spiny neurons (MSNs) giving rise to the direct and indirect output pathways in Huntington's disease (HD). MSNs of the indirect pathway appear to be particularly vulnerable and markers for these neurons are lost early in postmortem brains and in genetic mouse models. In contrast, MSNs of the direct pathway appear to be relatively spared in the early stages. Because of the great morphological and electrophysiological similarities between MSNs of these pathways, until recently it was difficult to tease apart their functional alterations in HD models. The recent use of the enhanced green fluorescent protein gene as a reporter to identify dopamine D1 (direct pathway) and D2 (indirect pathway) receptor-expressing MSNs has made it possible to examine synaptic function in each pathway. The outcomes of such studies demonstrate significant time-dependent changes in the balance of excitatory and inhibitory inputs to both direct and indirect pathway MSNs in HD and emphasize early increases in both excitatory and inhibitory inputs to direct pathway MSNs. There also is a strong influence of alterations in dopamine modulation that possibly cause some of the changes in excitatory and inhibitory synaptic transmission in the HD models. These changes will markedly alter the output structures, the GPi and the SNr. In the future, the use of combined optogenetics with identified neurons in each pathway will help unravel the next set of questions about how the output nuclei are affected in HD.

Dopamine imbalance in Huntington's disease: a mechanism for the lack of behavioral flexibility

Dopamine (DA) plays an essential role in the control of coordinated movements. Alterations in DA balance in the striatum lead to pathological conditions such as Parkinson's and Huntington's diseases (HD). HD is a progressive, invariably fatal neurodegenerative disease caused by a genetic mutation producing an expansion of glutamine repeats and is characterized by abnormal dance-like movements (chorea). The principal pathology is the loss of striatal and cortical projection neurons. Changes in brain DA content and receptor number contribute to abnormal movements and cognitive deficits in HD. In particular, during the early hyperkinetic stage of HD, DA levels are increased whereas expression of DA receptors is reduced. In contrast, in the late akinetic stage, DA levels are significantly decreased and resemble those of a Parkinsonian state. Time-dependent changes in DA transmission parallel biphasic changes in glutamate synaptic transmission and may enhance alterations in glutamate receptor-mediated synaptic activity. In this review, we focus on neuronal electrophysiological mechanisms that may lead to some of the motor and cognitive symptoms of HD and how they relate to dysfunction in DA neurotransmission. Based on clinical and experimental findings, we propose that some of the behavioral alterations in HD, including reduced behavioral flexibility, may be caused by altered DA modulatory function. Thus, restoring DA balance alone or in conjunction with glutamate receptor antagonists could be a viable therapeutic approach.

Frontal cortical synaptic communication is abnormal in Disc1 genetic mouse models of schizophrenia

Mouse models carrying Disc1 mutations may provide insights into how Disc1 genetic variations contribute to schizophrenia (SZ) susceptibility. Disc1 mutant mice show behavioral and cognitive disturbances reminiscent of SZ. To dissect the synaptic mechanisms underlying these phenotypes, we examined electrophysiological properties of cortical neurons from two mouse models, the first expressing a truncated mouse Disc1 (mDisc1) protein throughout the entire brain, and the second expressing a truncated human Disc1 (hDisc1) protein in forebrain regions. We obtained whole-cell patch clamp recordings to examine how altered expression of Disc1 protein changes excitatory and inhibitory synaptic transmissions onto cortical pyramidal neurons in the medial prefrontal cortex in 4-7 month-old mDisc1 and hDisc1 mice. In both mDisc1 and hDisc1 mice, the frequency of spontaneous EPSCs was greater than in wild-type littermate controls. Male mice from both lines were more affected by the Disc1 mutation than were females, exhibiting increases in the ratio of excitatory to inhibitory events. Changes in spontaneous IPSCs were only observed in the mDisc1 model and were sex-specific, with diminished cortical GABAergic neurotransmission, a well-documented characteristic of SZ, occurring only in male mDisc1 mice. In contrast, female mDisc1 mice showed an increase in the frequency of small-amplitude sIPSCs. These findings indicate that truncations of Disc1 alter glutamatergic and GABAergic neurotransmission both commonly and differently in the models and some of the effects are sex-specific, revealing how altered Disc1 expression may contribute to behavioral disruptions and cognitive deficits of SZ.

Healing Large Segmental Defects in Dogs and Sheep with Recombinant Human Bone Morphogenetic Protein (rhBMP-2)

Human recombinant BMP-2 is known to induce cartilage and bone in a rat subcutaneous site. Here we demonstrate that BMP-2 can induce therapeutic bony union in segmental bone defects in three different animal models: internally fixed defects in sheep femur (2.5 cm) and dog mandible (3.0 cm). In each model, inactive bone matrix from the same species as the test animal was prepared by acid demineralization and extraction in guanidinium chloride. Human recombinant BMP-2 was reconstituted with the bone matrix and inserted in the defect site. Inactive matrix served as the negative control. Healing was monitored weekly by x-ray, At the final time points, specimens were evaluated for union by biomechanical testing and for bone formation by histology. In the first model, a 3 cm mandibular defect in dogs was made and stabilized with a stainless steel reconstruction plate. Animals were terminated at 3 and 6 months. In the second model, an osteoperiosteal defect was created by excising a 2.5 cm midshaft segment from the femur of a skeletally mature sheep. The gap was stabilized by an anterolateral fixation plate. Animals were sacrificed at 12 weeks postoperation. In both studies, BMP-2 mixed with inactive carrier induced bony union judged by radiography, biomechanical testing, and histology; by the same criteria, the defect implanted with the carrier matrix alone did not unite.

The ability of demineralized bone to induce cartilage and bone formation in ectopic sites was described by Urist [1]; this activity was named bone morphogenetic protein (BMP). The in vivo progression of demineralized bone to bone has been well-studied [1,2]. After initial proliferation of mesenchymal cells in the first five days after implantation, a cartilage model forms at days 5–10. The cartilage mineralizes and hypertrophies, and is gradually replaced by bone. The newly formed bone then continues to remodel, so that in rats a thin ossicle of bone surrounding bone marrow has formed by day 21. The therapeutic potential of a material which could induce bone formation and replace bone graft is very high, and demineralized bone or partially purified protein prepared from demineralized bone has been used to repair large bony defects in animal models and in human therapy.

More recently, some of the individual components of the bone morphogenetic activity have been isolated and characterized from bovine bone [3]. Extensive biochemical purification and molecular cloning have demonstrated that there are at least 7 distinct proteins present in bone. Molecular cloning of the bone morphogenetic proteins (BMPs) 2 through 7 demonstrated that they are related and all are members of the transforming growth factor/inhibin family of genes [4,5,6]. There may also be additional factors involved in cartilage and bone induction, as other investigators have described components different from these [7,8]. Expression of the recombinant human BMP-2, BMP-3, BMP-4, BMP-5, and BMP-7 in mammalian cells, followed by purification, allowed the demonstration that an individual BMP is sufficient to induce cartilage and bone in an ectopic site. A detailed study in rats of BMP-2-induced bone formation showed that the progression seen with the recombinant protein is the same as observed with demineralized bone or highly purified bone-derived, bone-inductive proteins [9].

With this background of rhBMP-2-induced ectopic bone formation, this study demonstrates the efficacy of BMP-2 in healing a bony defect. Using allogeneic bone as a matrix, rhBMP-2 shows efficacy in healing large defects in dog mandible and sheep femur.

Asymptomatic large main pulmonary artery thromboembolism with a low-probability ventilation-perfusion lung scan

The incidence of the interpretation of low-probability lung scans in asymptomatic patients with large central pulmonary embolisms and the prognostic implication of the ventilation-perfusion scan appearance in this clinical setting is not documented.

Identification of a palmitic acid-modified form of human Sonic hedgehog

During hedgehog biosynthesis, autocatalytic processing produces a lipid-modified amino-terminal fragment (residues 24-197 in the human Sonic hedgehog sequence) that is responsible for all known hedgehog signaling activity and that is highly conserved evolutionarily. Published in vitro biochemical studies using Drosophila hedgehog identified the membrane anchor as a cholesterol, and localized the site of attachment to the COOH terminus of the fragment. We have expressed full-length human Sonic hedgehog in insect and in mammalian cells and determined by mass spectrometry that, in addition to cholesterol, the human hedgehog protein is palmitoylated. Peptide mapping and sequencing data indicate that the palmitoyl group is attached to the NH2 terminus of the protein on the alpha-amino group of Cys-24. Cell-free palmitoylation studies demonstrate that radioactive palmitic acid is readily incorporated into wild type Sonic hedgehog, but not into variant forms lacking the Cys-24 attachment site. The lipid-tethered forms of hedgehog showed about a 30-fold increase in potency over unmodified soluble hedgehog in a cell- based (C3H10T1/2 alkaline phosphatase induction) assay, suggesting that the lipid tether plays an important role in hedgehog function. The observation that an extracellular protein such as Shh is palmitoylated is highly unusual and further adds to the complex nature of this protein.

Bilayer free-standing beam splitter for Fourier transform infrared spectrometry

We describe the design, fabrication, testing, and performance of a two-layer free-standing beam splitter for use in far-infrared Fourier transform infrared spectrometers. This bilayer beam splitter, consisting of a low-index polymer layer in combination with a high-index semiconductor layer, has an efficiency that is higher than that of the best combination of four single-layer Mylar beam splitters currently in use for spectrometry from 50 to 550 cm(-1).

Induction of dopaminergic neuron phenotype in the midbrain by Sonic hedgehog protein

Loss of substantia nigra dopaminergic neurons, which develop from the ventral region of the midbrain, is associated with Parkinson's disease. During embryogenesis, induction of these and other ventral neurons is influenced by interactions with the induction of mesoderm of the notochord and the floor plate, which lies at the ventral midline of the developing CNS. Sonic hedgehog encodes a secreted peptide, which is expressed in notochord and floor plate cells and can induce appropriate ventral cell types in the basal forebrain and spinal cord. Here we demonstrate that Sonic hedgehog is sufficient to induce dopaminergic and other neuronal phenotypes in chick mesencephalic explants in vitro. We find that Sonic hedgehog is a general ventralizing signal in the CNS, the specific response being determined by the receiving cells. These results suggest that Sonic hedgehog may have utility in the induction of clinically important cell types.

Recombinant human bone morphogenetic protein-2 enhances expression of interleukin-6 and transforming growth factor-beta 1 genes in normal human osteoblast-like cells

The process of recombinant human bone morphogenetic protein-2 (rhBMP-2)-induced endochondral ossification involves 1) the proliferation and differentiation of mesenchymal cells into chondroblasts and osteoblasts; 2) the production and maturation of cartilage and bone matrix; and 3) the differentiation of circulating osteoclast precursor cells into osteoclasts. Currently the molecular mechanisms of these complex sequential events are unknown. It seemed reasonable to us to assume that communication between cells through soluble mediators during bone induction by rhBMP-2 may play an important role in the sequential differentiation of chondroblasts, osteoblasts, and osteoclasts. We have therefore used a human osteoblast-like initial transfectant cell line (HOBIT) to study the effect of rhBMP-2 on gene expression of interleukin-6 (IL-6) and transforming growth factor-beta 1 (TGF-beta 1), both of which affect osteogenesis and ostoeclastogenesis. Our results have demonstrated that rhBMP-2 acts on HOBIT cells to stimulate expression of IL-6 and TGF-beta 1 genes and the production of IL-6. Enhancement of gene expression of IL-6 and TGF-beta 1 by rhBMP-2 was both sensitive (half maximal effect at approximately 10 ng/ml) and potent (maximum induction was approximately four and threefold greater than controls, respectively). Time course studies showed that the induction of TGF-beta 1 and IL-6 mRNA occurs within short periods--4 and 8 hours after exposure to rhBMP-2, respectively. Interestingly, these effects, however, were not accompanied by the mitogenic action of rhBMP-2. It suggests that rhBMP-2 enhances IL-6 and TGF-beta 1 production during osteogenesis and at least in part mediates the complex sequential differentiation of chondroblasts, osteoblasts, and osteoclasts during rhBMP-2-induced endochondral ossification.

Bone morphogenetic proteins inhibit proliferation, induce reversible differentiation and prevent cell death in astrocyte lineage cells

Bone Morphogenetic Proteins (BMPs) induce the differentiation of Serum-free Mouse Embryo (SFME) cells into astrocytes (D'Alessandro et al., 1994) as demonstrated by change in morphology, increase in Glial Fibrillary Acidic Protein (GFAP) content and classification as both type 1 and 2 astrocytes. Further analyses showed that in the presence of BMP, cells which had differentiated into astrocytes were inhibited from proliferation. Moreover, removal of BMP resulted in a resumption of proliferation accompanied by a loss of GFAP expression over time, indicating that under these in vitro conditions the differentiation was reversible. Since EGF is absolutely required for the survival of SFME cells, we examined the effect of its removal in the presence of BMP. Cell survival was > 80% in the presence of BMP-2, 7 or 2/7 and < 10% in the presence of TGF-beta 1. These data demonstrate that BMPs have effects on the proliferation, differentiation and survival of cells in the astrocyte lineage.

Bone morphogenetic proteins induce differentiation in astrocyte lineage cells

Serum-free mouse embryo (SFME) cells express Glial Fibrillary Acidic Protein (GFAP), a specific marker of the astrocyte lineage, when treated with either Transforming Growth Factor Beta (TGF-beta) or calf serum. We examined the effects of the related Bone Morphogenetic Proteins (BMPs) which are expressed in the developing murine nervous system. Treatment with the heterodimers BMP-2/6 and 2/7 followed by the homodimers BMP-2, 4, 5, 6, and 7 induced higher levels of GFAP in these cells than either TGF-beta 1 or activin when tested at the same concentration. The BMP-induced cells resembled classically described astrocytes and were characterized by antibody markers as type 1 and type 2. In addition, these astrocytes also showed increased levels of the cell adhesion molecules CD44 and neural cell adhesion molecule (N-CAM), both known to be expressed by this cell type. These data clearly demonstrate that the BMPs function as differentiation factors as well as regulators of adhesion molecule expression for cells of the astrocyte lineage and suggest a key role in glial development in the nervous system.

Inhibition of matrix-induced bone differentiation by advanced glycation end-products in rats

Glycation of long-lived proteins is an inevitable consequence of aging that is accelerated in patients with diabetes mellitus. Treatment of demineralized bone matrix particles from 35-week-old normal Long-Evans rats with glycoaldehyde, a precursor of advanced glycation end-products, was used to assess the effects of bone-matrix glycation on the process of bone differentiation. Matrix was incubated in phosphate buffered saline alone, phosphate buffered saline containing glycolaldehyde, glycolaldehyde plus the advanced glycation product-inhibitor aminoguanidine, or glycolaldehyde plus the advanced glycation product-inhibitor sodium cyanoborohydride. Glycolaldehyde increased the matrix advanced glycation product content as measured by specific fluorescence more than two-fold, while inhibiting bone differentiation more than 90% as measured by in vivo 45CaCl2 uptake, alkaline phosphatase levels, and histology. In contrast, simultaneous incubation with the advanced glycation product-inhibitor aminoguanidine or sodium cyanoborohydride not only reduced fluorescence to normal, but also restored bone differentiation. Furthermore, the inhibition of bone differentiation by glycolaldehyde was not reversed by subsequent application of recombinant bone morphogenetic protein-2. These observations suggest that formation of advanced glycation products on bone matrix alters its ability to induce bone formation, and probably involves alterations of binding sites for extractable proteins with direct bone inductive properties such as bone morphogenetic protein-2. Decreased bone formation associated with aging and diabetes may result, in part, from advanced glycation product formation on matrix proteins.

Bone morphogenetic proteins (BMPs): therapeutic potential in healing bony defects

The bone morphogenetic proteins (BMPs) belong to a family of proteins that also includes the transforming growth factors beta (TGF-beta) and the inhibins. The BMPs can induce new bone formation in ectopic sites and therefore have enormous potential in bone repair. Studies of fracture-repair models involving BMP-2 suggest that this factor will be useful in healing bony defects in humans. Basic research on the BMPs predict a variety of activities on morphogenesis in systems other than cartilage and bone.

Bone morphogenetic protein-2 causes commitment and differentiation in C3H10T1/2 and 3T3 cells

C3H10T1/2 cells are an established mesenchymal stem cell line which can differentiate into muscle, fat and cartilage cells when treated with azacytidine. Bone morphogenetic protein-2 (BMP-2) caused a dose dependent differentiation of these cells into fat, cartilage and bone cells-low concentrations favoring adipocytes and high concentrations chondrocytes and osteoblasts. The differentiated phenotypes were stable in the absence of BMP-2. Furthermore, the addition of other growth factors during the differentiation process altered the frequency of the differentiated colony formation. Transfection of the C3H10T1/2 cells with a BMP-2 cDNA also induced a phenotypic change from the parental fibroblast to adipocytes and osteoblasts. Our results in this model system indicate that a single protein factor can cause differentiation of a stem cell line to multiple phenotypes, that phenotypes induced can be regulated by factor concentration, and that other factors can also influence BMP-2 induced differentiation.

The healing of segmental bone defects, induced by recombinant human bone morphogenetic protein (rhBMP-2). A radiographic, histological, and biomechanical study in rats

Subcutaneous implants of a recombinant human form of the bone-inducing protein rhBMP-2 (recombinant human bone morphogenetic protein-2) in rats have resulted in the local induction of endochondral bone formation. To test the osteoinductive activity of rhBMP-2 in an osseous location, we created five-millimeter segmental defects in the femora of forty-five adult male Sprague-Dawley rats. Two doses of lyophilized rhBMP-2 (1.4 or 11.0 micrograms) were implanted in each defect, together with guanidine-hydrochloride extracted demineralized rat-bone matrix as a carrier, and the results were compared with those in rats that had implantation of guanidine-hydrochloride extracted demineralized rat-bone matrix only. The formation and healing of bone were determined by radiographic, histological, and mechanical analysis. Both doses of rhBMP-2 induced formation of endochondral bone in the osseous defects in a dose-related manner. Implantation of 11.0 micrograms of rhBMP-2 yielded significant (p less than 0.05) bone formation, resulting in radiographic, histological, and mechanical evidence of union. Despite new-bone formation in the defects that had received 1.4 micrograms of rhBMP-2, no instances of union were observed.

Mandibular reconstruction with a recombinant bone-inducing factor. Functional, histologic, and biomechanical evaluation

Bone morphogenetic protein-2 (BMP-2) is a human recombinant bone-inducing factor that stimulates bone formation within 14 days. Twenty-six dogs underwent reconstruction of 3-cm full-thickness mandibular defects. After stabilizing the defects with stainless steel reconstruction plates, test implants composed of inactive dog bone matrix carrier and human recombinant BMP-2 were placed in defects of 12 animals (group 1). Control implants (carrier without BMP-2) were used in 10 animals (group 2), and no implants were placed in mandibular defects of four animals (group 3). Animals were killed at 3 and 6 months. The reconstructed segments were evaluated by roentgenography, analysis of functional stability, histology, histomorphometry, and analysis of biomechanical strength using three-point bend testing. In group 1, reconstruction plates were removed at 10 weeks because stiff, noncompressible mineralized bone formed across the defects, allowing the animals to chew a solid diet. The defects from groups 2 and 3 showed minimal, if any, bone formation and remained grossly unstable, prohibiting plate removal or advancement to a solid diet. Histomorphometric analysis at 6 months revealed that 68% of the group 1 implants were replaced by mineralized bone, whereas mineralized bone occupied less than 4% of the implants in groups 2 and 3. Biomechanical testing at 6 months revealed that the average bending strength of the reconstructed hemimandibles (expressed as a percentage of the contralateral hemimandible) was 27% for group 1 and 0% for group 2. The biomechanical strength of the defects reconstructed with BMP-2 increased significantly from 3 to 6 months and was related to degree of mineralization and thickness of bone bridging the defect.

Recombinant human bone morphogenetic protein-2 stimulates osteoblastic maturation and inhibits myogenic differentiation in vitro

The in vitro effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on osteogenic and myogenic differentiation was examined in two clonal cell lines of rat osteoblast-like cells at different differentiation stages, ROB-C26 (C26) and ROB-C20 (C20). The C26 is a potential osteoblast precursor cell line that is also capable of differentiating into muscle cells and adipocytes; the C20 is a more differentiated osteoblastic cell line. Proliferation was stimulated by rhBMP-2 in C26 cells, but inhibited in C20 cells. rhBMP-2 greatly increased alkaline phosphate (ALP) activity in C26 cells, but not in C20 cells. The steady-state level of ALP mRNA was also increased by rhBMP-2 in C26 cells, but not in C20 cells. Production of 3',5'-cAMP in response to parathyroid hormone (PTH) was dose-dependently enhanced by adding rhBMP-2 in both C26 and C20 cells, though the stimulatory effect was much greater in the former. There was neither basal expression of osteocalcin mRNA nor its protein synthesis in C26 cells, but they were strikingly induced by rhBMP-2 in the presence of 1 alpha,25-dihydroxyvitamin D3. rhBMP-2 induced no appreciable changes in procollagen mRNA levels of type I and type III in the two cell lines. Differentiation of C26 cells into myotubes was greatly inhibited by adding rhBMP-2. The inhibitory effect of rhBMP-2 on myogenic differentiation was also observed in clonal rat skeletal myoblasts (L6). Like BMP-2, TGF-beta 1 inhibited myogenic differentiation. However, unlike BMP-2, TGF-beta 1 decreased ALP activity in both C26 and C20 cells. TGF-beta 1 induced neither PTH responsiveness nor osteocalcin production in C26 cells, but it increased PTH responsiveness in C20 cells. These results clearly indicate that rhBMP-2 is involved, at least in vitro, not only in inducing differentiation of osteoblast precursor cells into more mature osteoblast-like cells, but also in inhibiting myogenic differentiation.

Identification of transforming growth factor beta family members present in bone-inductive protein purified from bovine bone

Characterization of the polypeptides present in bone-inductive protein extracts from bovine bone has led to the cloning of seven regulatory molecules, six of which are distantly related to transforming growth factor beta. The three human bone morphogenetic proteins (BMPs) we describe herein, BMP-5, BMP-6, and BMP-7, show extensive sequence similarity to BMP-2, a molecule that by itself is sufficient to induce de novo bone formation in vivo. The additive or synergistic contribution of these BMP-2-related molecules to the osteogenic activity associated with demineralized bone is strongly implicated by the presence of these growth factors in the most active fractions of highly purified bone extract.

The non-osteogenic mouse pluripotent cell line, C3H10T1/2, is induced to differentiate into osteoblastic cells by recombinant human bone morphogenetic protein-2

The possibility that the non-osteogenic mouse pluripotent cell line, C3H10T1/2 (10T1/2), could be induced to differentiate into osteogenic cells by various hormones and cytokines was examined in vitro. Of a number of agents tested, recombinant human bone morphogenetic protein-2 (rhBMP-2) and retinoic acid induced alkaline phosphatase (ALP) activity in 10T1/2 cells. rhBMP-2 also induced mRNA expression of ALP in the cells. Dexamethasone, 1 alpha, 25-dihydroxyvitamin D3, transforming growth factor-beta 1 and insulin-like growth factor-I did not stimulate ALP activity. Treatment with rhBMP-2 greatly induced cAMP production in response to parathyroid hormone in 10T1/2 cells. No ALP activity was induced in NIH3T3 fibroblasts treated with rhBMP-2 or retinoic acid. These results indicate that 10T1/2 cells have a potential to differentiate into osteogenic cells under the control of BMP-2.

Recombinant human bone morphogenetic protein induces bone formation

We have purified and characterized active recombinant human bone morphogenetic protein (BMP) 2A. Implantation of the recombinant protein in rats showed that a single BMP can induce bone formation in vivo. A dose-response and time-course study using the rat ectopic bone formation assay revealed that implantation of 0.5-115 micrograms of partially purified recombinant human BMP-2A resulted in cartilage by day 7 and bone formation by day 14. The time at which bone formation occurred was dependent on the amount of BMP-2A implanted; at high doses bone formation could be observed at 5 days. The cartilage- and bone-inductive activity of the recombinant BMP-2A is histologically indistinguishable from that of bone extracts. Thus, recombinant BMP-2A has therapeutic potential to promote de novo bone formation in humans.

Growth factors influencing bone development

We have approached the study of growth factors affecting cartilage and bone development by investigating those factors present in bone which are able to initiate new cartilage and bone formation in vivo. This has led to the identification and molecular cloning of seven novel human factors which we have named BMP-1 through BMP-7. Six of these molecules are related to each other, and are also distantly related to TGF-beta. The presence of one of these molecules, recombinant human BMP-2 (rhBMP-2) is sufficient to produce the complex developmental system of cartilage and bone formation when implanted subcutaneously in a rat assay system. In this model, administration of rhBMP-2 ultimately results in the formation of a piece of trabecular bone, which is filled with mature bone marrow. While our studies demonstrate that rhBMP-2 by itself has the ability to induce cartilage and bone formation in vivo, we find other BMP molecules present along with BMP-2 in our highly purified nonrecombinant bone-inductive material. These results suggest that the bone inductive capacity of bone-derived proteins may reside in the combinatorial or synergistic activities of this set of BMP-2 related molecules.

Purification and molecular cloning of a novel group of BMPs and localization of BMP mRNA in developing bone

Using a novel purification scheme, we have characterized BMP as a 30kD fraction. After reduction, which destroys biological activity, this fraction was shown to be comprised of individual polypeptides with molecular weights of 30kD, 18kD and 16kD. Molecular cloning of these polypeptides resulted in the identification of 4 previously undescribed genes (BMP-1, BMP-2A, BMP-2B, and BMP-3) each of which is capable of directing de novo cartilage formation in vivo. While BMP-1 appears to be unrelated to other known growth factors, the derived amino acid sequence of BMP-2A, 2B, and 3 indicate that they are new members of the TGFb gene family. BMP-1, 2A and 2B are expressed in rat embryos during morphogenesis and can be localized by in situ hybridization to developing limb buds. BMP-3 localizes to neural ectoderm and later on in development to newly forming periosteum. Comparisons to other members of the TGFb family suggest that these newly identified BMPs are involved in pattern formation during early skeletal development.

Novel regulators of bone formation: molecular clones and activities

Protein extracts derived from bone can initiate the process that begins with cartilage formation and ends in de novo bone formation. The critical components of this extract, termed bone morphogenetic protein (BMP), that direct cartilage and bone formation as well as the constitutive elements supplied by the animal during this process have long remained unclear. Amino acid sequence has been derived from a highly purified preparation of BMP from bovine bone. Now, human complementary DNA clones corresponding to three polypeptides present in this BMP preparation have been isolated, and expression of the recombinant human proteins have been obtained. Each of the three (BMP-1, BMP-2A, and BMP-3) appears to be independently capable of inducing the formation of cartilage in vivo. Two of the encoded proteins (BMP-2A and BMP-3) are new members of the TGF-beta supergene family, while the third, BMP-1, appears to be a novel regulatory molecule.

Purification and characterization of other distinct bone-inducing factors

We purified a factor that induces bone formation greater than 300,000-fold from guanidinium chloride extracts of demineralized bone. Fifty nanograms of highly purified protein was active in an in vivo cartilage and bone-formation assay. The activity resided in a single gel band, corresponding to a molecular mass of approximately 30 kDa, which yielded proteins of 30, 18, and 16 kDa on reduction. The partial amino acid sequence obtained from these proteins confirmed our identification of specific factors that induce new bone formation in vivo.

Isolation of the human gene for bone gla protein utilizing mouse and rat cDNA clones

cDNAs which encode bone gla protein (BGP), an abundant gamma-carboxylated protein of bone, have been cloned from rat and mouse osteosarcoma cell lines. DNA sequence analysis indicates that the cDNAs code for both the 50 (rat) or 46 (mouse) amino acids of the mature proteins and a 49 amino acid leader peptide. The leader peptide of each BGP includes the expected hydrophobic signal sequence and an apparent pro sequence. Although there is no homology between the mature forms of BGP and the gamma-carboxylated clotting factors, we note that there is some homology between their leader peptides. These cDNAs have been used to examine the modulation of BGP mRNA levels by osteoblastic cells in response to hormones. The cDNAs have also allowed isolation of the human BGP gene; analysis of this gene indicates the presence of four exons. Comparison of the exon structure of the BGP gene and the Factor IX (a gamma-carboxylated clotting factor) gene suggests that the exons encoding the part of the leader peptides presumably directing gamma-carboxylation arose from a common ancestral sequence.