BackgroundMonogenic diseases provide favorable opportunities to elucidate the molecular mechanisms of disease progression and improve medical diagnostics. However, the complex interplay between genetic and environmental factors in disease etiologies makes it difficult to discern the mechanistic links between different alleles of a single locus and their associated pathophysiologies. Inverted formin 2 (INF2), an actin regulator, mediates a stress response—calcium mediated actin reset, or CaAR—that reorganizes the actin cytoskeleton of mammalian cells in response to calcium influx. It has been linked to the podocytic kidney disease focal segemental glomerulosclerosis (FSGS), as well as to cases of the neurologic disorder Charcot–Marie–Tooth disease that are accompanied by nephropathy, mostly FSGS.MethodsWe used a combination of quantitative live cell imaging and validation in primary patient cells and Drosophila nephrocytes to systematically characterize a large panel of >50 autosomal dominant INF2 mutants that have been reported to cause either FSGS alone or with Charcot–Marie–Tooth disease.ResultsWe found that INF2 mutations lead to deregulated activation of formin and a constitutive stress response in cultured cells, primary patient cells, and Drosophila nephrocytes. We were able to clearly distinguish between INF2 mutations that were linked exclusively to FSGS from those that caused a combination of FSGS and Charcot–Marie–Tooth disease. Furthermore, we were able to identify distinct subsets of INF2 variants that exhibit varying degrees of activation.ConclusionsOur results suggest that CaAR can be used as a sensitive assay for INF2 function and for robust evaluation of diseased-linked variants of formin. More broadly, these findings indicate that cellular profiling of disease-associated mutations has potential to contribute substantially to sequence-based phenotype predictions.

<b><i>Introduction:</i></b> Symptoms of allergic rhinitis can be reduced by nonpharmacological nasal sprays that create a barrier between allergens and the nasal mucosa. A new nasal spray (AM-301) containing the clay mineral bentonite was tested for its ability to reduce symptoms of grass pollen. <b><i>Methods:</i></b> This open-label, crossover, noninferiority trial compared the efficacy and safety of AM-301 to that of hydroxypropyl methylcellulose (HPMC; Nasaleze® Allergy Blocker), an established barrier method. Adults with seasonal allergic rhinitis were exposed to <i>Dactylis glomerata</i> pollen, in a controlled setting, the Fraunhofer allergen challenge chamber, first without protection and then protected by HPMC or AM-301 (7 days apart). Efficacy was assessed from total nasal symptom score (TNSS), nasal secretion weight, and subjective rating. The primary endpoint was the difference, between AM-301 and HPMC, in least square mean change in TNSS over a 4-h exposure to allergen. <b><i>Results:</i></b> The study enrolled 36 persons, and 35 completed all study visits. The mean TNSS was 5.91 (SD = 1.45) during unprotected exposure, 5.20 (SD = 1.70) during protection with HPMC, and 4.82 (SD = 1.74) during protection with AM-301. The difference in least square means between the two treatments was −0.39 (95% CI: −0.89 to 0.10), establishing the noninferiority of AM-301. No difference in mean weight of nasal secretions was observed between the treatments. Efficacy was rated as good or very good for AM-301 by 31% and for HPMC by 14% of subjects. Sixteen subjects reported adverse events with a relationship to AM-301 or HPMC; most adverse events were mild, and none was serious. <b><i>Discussion/Conclusion:</i></b> AM-301 demonstrated noninferiority toward HPMC in the primary endpoint and was perceived better in subjective secondary endpoints. Both barrier-forming products had a persisting protective effect over 4 h and were safe.

Monogenic diseases provide favorable opportunities to elucidate the molecular mechanisms of disease progression and improve medical diagnostics. However, the complex interplay between genetic and environmental factors in disease etiologies makes it difficult to discern the mechanistic links between different alleles of a single locus and their associated pathophysiologies. Here we systematically characterize a large panel (>50) of autosomal dominant mutants of the actin regulator inverted formin 2 (INF2) that have been reported to cause the podocytic kidney disease focal segmental glomerulosclerosis (FSGS) and the neurological disorder Charcot Marie-Tooth disease (CMT). We found that INF2 mutations lead to deregulated activation of the formin and a constitutive stress response in cultured cells, primary patient cells and Drosophila nephrocytes.Using quantitative live-cell imaging we were able to identify distinct subsets of INF2 variants that exhibit varying degrees of activation. Furthermore, we could clearly distinguish between INF2 mutations that were linked exclusively to FSGS from those that caused a combination of FSGS and CMT. Our results indicate that cellular profiling of disease-associated mutations can contribute substantially to sequence-based phenotype predictions.

BackgroundSymptoms of allergic rhinitis can be reduced by nonpharmacological nasal sprays that create a barrier between allergens and the nasal mucosa. A new nasal spray (AM-301) containing the clay mineral bentonite was tested for its ability to reduce symptoms to grass pollen.MethodsThis open label, crossover, noninferiority trial compared the efficacy and safety of AM-301 to that of hydroxypropyl methylcellulose (HPMC; Nasaleze Allergy Blocker), an established barrier method. Adults with seasonal allergic rhinitis were exposed to Dactylis glomerata pollen, in the Fraunhofer Allergen Challenge Chamber, first without protection and then protected by HPMC or AM-301 (7 days apart). Efficacy was assessed from total nasal symptom score (TNSS), nasal secretion weight, and subjective rating. The primary endpoint was the difference, between AM-301 and HPMC, in least square mean change in TNSS over a 4-hour exposure to allergen.ResultsThe study enrolled 36 persons, and 35 completed all study visits. The mean TNSS was 5.91 during unprotected exposure, 5.20 during protection with HPMC, and 4.82 during protection with AM-301. The difference in least square means between the two treatments was -0.39 (95% CI, -0.89 to 0.10), establishing the noninferiority of AM-301. No difference in mean weight of nasal secretions was observed between the treatments. Efficacy was rated as good or very good for AM-301 by 31% and for HPMC by 14% of subjects. 16 subjects reported adverse events with a relationship to AM-301 or HPMC; most adverse events were mild and none was serious.ConclusionsAM-301 demonstrated noninferiority towards HPMC in the primary endpoint and was perceived better in subjective secondary endpoints. Both barrier-forming products had a persisting protective effect over 4 hours and were safe.Trial registrationGerman Clinical Trial Register (DRKS00024356). EUDAMED (CIV-20-10-034870).

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