Alpha1-antitrypsin impacts innate host-pathogen interactions with Candida albicans by stimulating fungal filamentation

Our immune system possesses sophisticated mechanisms to cope with invading microorganisms, while pathogens evolve strategies to deal with threats imposed by host immunity. Human plasma protein α1-antitrypsin (AAT) exhibits pleiotropic immune-modulating properties by both preventing immunopathology and improving antimicrobial host defence. Genetic associations suggested a role for AAT in candidemia, the most frequent fungal blood stream infection in intensive care units, yet little is known about how AAT influences interactions between Candida albicans and the immune system. Here, we show that AAT differentially impacts fungal killing by innate phagocytes. We observed that AAT induces fungal transcriptional reprogramming, associated with cell wall remodelling and downregulation of filamentation repressors. At low concentrations, the cell-wall remodelling induced by AAT increased immunogenic β-glucan exposure and consequently improved fungal clearance by monocytes. Contrastingly, higher AAT concentrations led to excessive C. albicans filamentation and thus promoted fungal immune escape from monocytes and macrophages. This underscores that fungal adaptations to the host protein AAT can differentially define the outcome of encounters with innate immune cells, either contributing to improved immune recognition or fungal immune escape.

Effects of single-channel phonemic compression schemes on the understanding of speech by hearing-impaired listeners

The effect of digital processing on speech intelligibility was studied in hearing-impaired listeners with moderate to severe high-frequency losses. The amount of smoothed phonemic compression in a high-frequency channel was varied using wide-band control. Two alternative systems were tested to compensate for upward spread of masking (USOM) and to reduce modulations in the high-frequency channel effectively. Consonant-vowel-consonant tests were conducted in a group of 14 subjects using eight different speech-processing settings. Speech intelligibility improved significantly with compression, mainly due to positive effects on the initial-consonant score. Surprisingly, listeners with a smaller residual dynamic range tended to profit less from compression. Compensation for USOM gave an additional improvement of vowel intelligibility. In background noise, consistently negative effects of speech processing were found. The combined use of phonemic compression and USOM compensation is promising in conditions without background noise.