Topical Nitrogen Mustard for the Treatment of Granulomatous Slack Skin

Granulomatous slack skin (GSS) is a rare variant of mycosis fungoides in which inflammation leads to elastolysis manifested by pendulous skin folds with a predilection for flexural areas. Histologic findings include many multinucleated giant cells with large numbers of nuclei and loss of dermal elastic tissue. Definitive therapy has yet to be established, but recently interferon-alpha and radiation, interferon-gamma, and pentostatin have shown some success in the treatment of GSS. We present two cases of GSS treated with topical nitrogen mustard (chlormethine; mechlorethamine; mustine), one of whom has long-term remission and the other partial remission. Topical nitrogen mustard appears to be an effective skin-directed therapy for this rare condition.     

Epidermodysplasia verruciformis occurring in a patient with human immunodeficiency virus: a case report

Epidermodysplasia verruciformis (EV) is an uncommon dermatosis associated with human papillomavirus (HPV) infection in association with defects in cell-mediated immunity. Malignant transformation to squamous cell carcinoma has been associated with lesions caused by HPV-5, HPV-8, and HPV-14. Clinically, the disease may be confused with verruca plana, seborrheic keratosis, and pityriasis versicolor. We present an unusual case of EV occurring in a human immunodeficiency virus (HIV)-positive man and discuss the clinical and histologic findings. Clinically, the patient had 1- to 3-mm hypopigmented smooth macules covering the entire body. Histopathologic examination of the skin biopsy results demonstrated enlarged keratinocytes with prominent blue-gray cytoplasm and clumping of keratohyalin granules within the granular layer of the epidermis. Although EV typically is viewed as a disease of childhood, sometimes presenting in patients with a family history of the disease, it rarely may be seen in immunocompromised adults.     

Characteristic muscle signatures assessed by quantitative MRI in patients with Bethlem myopathy

Journal of Neurology - Using MRI, the main aim was to (1) map the pattern of muscle involvement by assessing fat fraction and (2) investigate frequency of target and sandwich signs in 42 muscles of...     

Real-time evaluation of glioblastoma growth in patient-specific zebrafish xenografts

BackgroundPatient-derived xenograft (PDX) models of glioblastoma (GBM) are a central tool for neuro-oncology research and drug development, enabling the detection of patient-specific differences in growth, and in vivo drug response. However, existing PDX models are not well suited for large-scale or automated studies. Thus, here, we investigate if a fast zebrafish-based PDX model, supported by longitudinal, AI-driven image analysis, can recapitulate key aspects of glioblastoma growth and enable case-comparative drug testing.MethodsWe engrafted 11 GFP-tagged patient-derived GBM IDH wild-type cell cultures (PDCs) into 1-day-old zebrafish embryos, and monitored fish with 96-well live microscopy and convolutional neural network analysis. Using light-sheet imaging of whole embryos, we analyzed further the invasive growth of tumor cells.ResultsOur pipeline enables automatic and robust longitudinal observation of tumor growth and survival of individual fish. The 11 PDCs expressed growth, invasion and survival heterogeneity, and tumor initiation correlated strongly with matched mouse PDX counterparts (Spearman R = 0.89, p < 0.001). Three PDCs showed a high degree of association between grafted tumor cells and host blood vessels, suggesting a perivascular invasion phenotype. In vivo evaluation of the drug marizomib, currently in clinical trials for GBM, showed an effect on fish survival corresponding to PDC in vitro and in vivo marizomib sensitivity.ConclusionsZebrafish xenografts of GBM, monitored by AI methods in an automated process, present a scalable alternative to mouse xenograft models for the study of glioblastoma tumor initiation, growth, and invasion, applicable to patient-specific drug evaluation.     

The cellular microenvironment regulates CX3CR1 expression on CD8+ T cells and the maintenance of CX3CR1+ CD8+ T cells

Expression levels of the chemokine receptor CX3CR1 serve as high-resolution marker delineating functionally distinct antigen-experienced T-cell states. The factors that influence CX3CR1 expression in T cells are, however, incompletely understood. Here, we show that in vitro priming of naïve CD8⁺ T cells failed to robustly induce CX3CR1, which highlights the shortcomings of in vitro priming settings in recapitulating in vivo T-cell differentiation. Nevertheless, in vivo generated memory CD8⁺ T cells maintained CX3CR1 expression during culture. This allowed us to investigate whether T-cell receptor ligation, cell death, and CX3CL1 binding influence CX3CR1 expression. T-cell receptor stimulation led to downregulation of CX3CR1. Without stimulation, CX3CR1⁺ CD8⁺ T cells had a selective survival disadvantage, which was enhanced by factors released from necrotic but not apoptotic cells. Exposure to CX3CL1 did not rescue their survival and resulted in a dose-dependent loss of CX3CR1 surface expression. At physiological concentrations of CX3CL1, CX3CR1 surface expression was only minimally reduced, which did not hamper the interpretability of T-cell differentiation states delineated by CX3CR1. Our data further support the broad utility of CX3CR1 surface levels as T-cell differentiation marker and identify factors that influence CX3CR1 expression and the maintenance of CX3CR1 expressing CD8⁺ T cells.     

Update on neuroblastoma

Neuroblastoma is an embryonic cancer arising from neural crest stem cells. This cancer is the most common malignancy in infants and the most common extracranial solid tumor in children. The clinical course may be highly variable with the possibility of spontaneous regression in the youngest patients and increased risk of aggressive disease in older children. Clinical heterogeneity is a consequence of the diverse biologic characteristics that determine patient risk and survival. This review will focus on current progress in neuroblastoma staging, risk stratification, and treatment strategies based on advancing knowledge in tumor biology and genetic characterization.

INAUGURAL ARTICLE by a Recently Elected Academy Member:Positively selected FimH residues enhance virulence during urinary tract infection by altering FimH conformation

Chaperone–usher pathway pili are a widespread family of extracellular, Gram-negative bacterial fibers with important roles in bacterial pathogenesis. Type 1 pili are important virulence factors in uropathogenic Escherichia coli (UPEC), which cause the majority of urinary tract infections (UTI). FimH, the type 1 adhesin, binds mannosylated glycoproteins on the surface of human and murine bladder cells, facilitating bacterial colonization, invasion, and formation of biofilm-like intracellular bacterial communities. The mannose-binding pocket of FimH is invariant among UPEC. We discovered that pathoadaptive alleles of FimH with variant residues outside the binding pocket affect FimH-mediated acute and chronic pathogenesis of two commonly studied UPEC strains, UTI89 and CFT073. In vitro binding studies revealed that, whereas all pathoadaptive variants tested displayed the same high affinity for mannose when bound by the chaperone FimC, affinities varied when FimH was incorporated into pilus tip-like, FimCGH complexes. Structural studies have shown that FimH adopts an elongated conformation when complexed with FimC, but, when incorporated into the pilus tip, FimH can adopt a compact conformation. We hypothesize that the propensity of FimH to adopt the elongated conformation in the tip corresponds to its mannose binding affinity. Interestingly, FimH variants, which maintain a high-affinity conformation in the FimCGH tip-like structure, were attenuated during chronic bladder infection, implying that FimH’s ability to switch between conformations is important in pathogenesis. Our studies argue that positively selected residues modulate fitness during UTI by affecting FimH conformation and function, providing an example of evolutionary tuning of structural dynamics impacting in vivo survival.Urinary tract infections (UTIs) are common infections causing serious morbidity and significant expenditures in healthcare dollars and lost wages. Women are disproportionately affected, with over half of women experiencing at least one UTI during their lifetime (1). In the absence of treatment, 50–80% of women will resolve a UTI within 2 mo, but up to 60% of women may remain bacteriuric with or without symptoms for at least 5–7 wk after the initial infection (2). Furthermore, even when effective therapy is given and bacteriuria and symptoms of the acute UTI resolve, 25–40% of women experience a recurrent UTI (rUTI) (2, 3). rUTI can occur by recolonization of the urinary tract from the gastrointestinal (GI) tract or from another environmental source by the same or different strain or may be due to reactivation of the original UTI strain from a bladder reservoir (4–6). Uropathogenic Escherichia coli (UPEC) cause 80–90% of community-acquired UTI and 50% of nosocomial UTI (7). The increasing prevalence of multidrug-resistant organisms can prolong the infection (8). Thus, chronic and recurrent UTI represents a major health concern worldwide, necessitating molecular understanding of disease pathogenesis and investigations into novel diagnostics and therapies.UTI is a highly complex disease involving colonization of multiple niches, each of which presents a unique set of evolutionary pressures shaping host–microbe and microbe–microbe interactions involving a multitude of virulence factors that determine disease onset, progression, and outcome. Adhesive pili assembled by the chaperone–usher pathway (CUP), such as type 1 pili, are well-characterized UPEC UTI virulence determinants. Type 1 pili, like other CUP pili, contain an adhesin (FimH) at their tip that plays an important role in host–pathogen interactions and biofilm formation. Type 1 pili are nearly ubiquitous among clinical UPEC isolates (9, 10) as well as commensal E. coli and other Enterobacteriaceae. Expression of type 1 pili is essential for colonization of the murine urinary tract (11); however, expressing type 1 pili is not sufficient for long-term colonization, as commensal E. coli are rapidly cleared (12).Upon UPEC entrance into the bladder, FimH binds mannosylated glycoproteins, including uroplakins expressed throughout human and murine bladders (13). Subsequent to attachment, UPEC invade superficial facet cells in a FimH-dependent manner (12, 14) and replicate in the cytoplasm, forming large biofilm-like structures called intracellular bacterial communities (IBCs) (15). The formation of IBCs has been observed for numerous clinical UPEC isolates in multiple mouse models and in exfoliated uroepithelial cells in urines of patients with acute UTI, but not from healthy controls (16, 17). The process of invasion and IBC formation provides UPEC an ability to survive stringent bottlenecks during pathogenesis in the urinary tract (18, 19). Outcomes of infection range from resolution with or without accompanying quiescent intracellular reservoirs (QIRs) in the bladder tissue (4) to persistent bacteriuria and chronic cystitis (20). In C3H/HeN mice, the formation of a high number of IBCs at 6 h postinfection (hpi) and an exuberant systemic innate immune response at 24 hpi, measurable in both urine and serum, correlate with the development of chronic cystitis marked by persistent urine and bladder titers >10⁴ cfu/mL and severe bladder immunopathology (18, 20). In addition to colonizing the bladder, UPEC can ascend the ureters and infect the kidneys, leading to pyelonephritis. The connection between acute and chronic UTI is just now beginning to be characterized (21–23).Type 1 pili and the tip adhesin, FimH, are encoded by the fim operon (24, 25). Mature FimH is a 279-aa two-domain protein containing a mannose-binding lectin domain (residues 1–150) and a pilin domain (residues 159–279) with an 8-aa linker connecting the domains (Fig. 1) (26–28). The mannose-binding pocket of FimH is invariant among sequenced UPEC (26, 29); however, several residues outside the mannose-binding pocket (positions 27, 62, 66, and 163) were found to be evolving under positive selection in clinical UPEC isolates compared with fecal strains (Fig. 1) (29, 30, 31). Among four fully sequenced UPEC isolates (UTI89, CFT073, 536, and J96), differences exist in positively selected residues 27, 62, and 163 (16) and the development of chronic cystitis (20). We found that UTI89, a cystitis isolate, formed more IBCs and had higher bladder titers at 6 hpi than CFT073, a pyelonephritis isolate, in single infections and coinfections. Because of the demonstrated importance of type 1 pilus function in pathogenesis, we conducted fimH allele swap experiments to determine whether the differences in fimH between UPEC strains were responsible for the phenotypic differences. We generated CFT073 and UTI89 strains containing different fimH alleles inserted into the normal chromosomal position. We found that presence of a fimH sequence encoding FimH from UTI89 (denoted FimH::A62/V163) resulted in significant increases in IBC development and the propensity to cause chronic cystitis compared with expression of CFT073 FimH (FimH::S62/A163). In coinfections, strains expressing FimH::A62/V163 significantly outcompeted otherwise isogenic strains harboring FimH::S62/A163 in both CFT073 and UTI89. FimH complexed with its chaperone FimC adopts an elongated conformation (Fig. 1A), which binds mannose with high affinity (26, 37). When complexed with the FimG adaptor, FimH can adopt a compact conformation that binds mannose with low affinity (Fig. 1B) (37). The identity of residues at positively selected positions outside the binding pocket dramatically impacts the mannose binding affinity of FimH when in the FimCGH tip-like complex but not in the FimCH complex. Thus, we argue that the combination of residues at positively selected positions affects the propensity of FimH to adopt an elongated conformation in the tip and thus its relative mannose binding affinity. FimH alleles that retained the high-affinity binding conformation in the tip were significantly attenuated in a mouse model of UTI, suggesting that equilibrium between FimH conformations, which is modulated by positively selected residues, is critical in pathogenesis.Open in a separate windowFig. 1.FimH positively selected residues. FimH is a two-domain adhesin comprised of a lectin domain of residues 1–150 (green), a pilin domain with residues 159–279 (blue), and a linker loop (yellow) connecting them. Positively selected residues are mapped onto the structures of FimH as red spheres. (A) In the elongated FimH (V27/S62/V163) structure, mannose is observed at the distal binding pocket in white sticks (J96 FimH; PDB ID code: 1KLF; FimC removed for clarity). (B) In the compressed FimH (A27/S62/A163) structure in the absence of mannose, position 133 of the binding pocket is colored white (F18 FimH; PDB ID code: 3JWN). Note the distance of these positively selected residues from the mannose binding pocket.

Table 1.

Prevalence of positively selected FimH residues

Combinatorial Small-Molecule Therapy Prevents Uropathogenic Escherichia coli Catheter-Associated Urinary Tract Infections in Mice

Catheter-associated urinary tract infections (CAUTIs) constitute the majority of nosocomial urinary tract infections (UTIs) and pose significant clinical challenges. These infections are polymicrobial in nature and are often associated with multidrug-resistant pathogens, including uropathogenic Escherichia coli (UPEC). Urinary catheterization elicits major histological and immunological alterations in the bladder that can favor microbial colonization and dissemination in the urinary tract. We report that these biological perturbations impact UPEC pathogenesis and that bacterial reservoirs established during a previous UPEC infection, in which bacteriuria had resolved, can serve as a nidus for subsequent urinary catheter colonization. Mannosides, small molecule inhibitors of the type 1 pilus adhesin, FimH, provided significant protection against UPEC CAUTI by preventing bacterial invasion and shifting the UPEC niche primarily to the extracellular milieu and on the foreign body. By doing so, mannosides potentiated the action of trimethoprim-sulfamethoxazole in the prevention and treatment of CAUTI. In this study, we provide novel insights into UPEC pathogenesis in the context of urinary catheterization, and demonstrate the efficacy of novel therapies that target critical mechanisms for this infection. Thus, we establish a proof-of-principle for the development of mannosides to prevent and eventually treat these infections in the face of rising antibiotic-resistant uropathogens.