Mucorales can cause cutaneous to deep-seated infections, mainly in the immunocompromised host, resulting in high mortality rates due to late and inefficient treatment. In this study, Galleria mellonella larvae were evaluated as a heterologous invertebrate host to study pathogenicity of clinically relevant mucormycetes (Rhizopus spp., Rhizomucor spp., Lichtheimia spp., Mucor spp.). All tested species were able to infect G. mellonella larvae. Virulence potential was species-specific and correlated to clinical relevance. Survival of infected larvae was dependent on (a) the species (growth speed and spore size), (b) the infection dose, (c) the incubation temperature, (d) oxidative stress tolerance, and (e) iron availability in the growth medium. Moreover, we exploited the G. mellonella system to determine antifungal efficacy of liposomal amphotericin B, posaconazole, isavuconazole, and nystatin-intralipid. Outcome of in vivo treatment was strongly dependent upon the drug applied and the species tested. Nystatin-intralipid exhibited best activity against Mucorales, followed by posaconazole, while limited efficacy was seen for liposomal amphotericin B and isavuconazole. Pharmacokinetic properties of the tested antifungals within this alternative host system partly explain the limited treatment efficacy. In conclusion, G. mellonella represents a useful invertebrate infection model for studying virulence of mucormycetes, while evaluation of treatment response was limited.

Angiotensin-converting enzyme (ACE) converts angiotensin I into the potent vasoconstrictor angiotensin II, which regulates blood pressure. However, ACE activity is also essential for other physiological functions, presumably through processing of peptides unrelated to angiotensin. The goal of this study was to identify novel natural substrates and products of ACE through a series of mass-spectrometric experiments. This included comparing the ACE-treated and untreated plasma peptidomes of ACE-knockout (KO) mice, validation with select synthetic peptides, and a quantitative in vivo study of ACE substrates in mice with distinct genetic ACE backgrounds. In total, 244 natural peptides were identified ex vivo as possible substrates or products of ACE, demonstrating high promiscuity of the enzyme. ACE prefers to cleave substrates with Phe or Leu at the C-terminal P2′ position and Gly in the P6 position. Pro in P1′ and Iso in P1 are typical residues in peptides that ACE does not cleave. Several of the novel ACE substrates are known to have biological activities, including a fragment of complement C3, the spasmogenic C3f, which was processed by ACE ex vivo and in vitro. Analyses with N-domain-inactive (NKO) ACE allowed clarification of domain selectivity toward substrates. The in vivo ACE-substrate concentrations in WT, transgenic ACE-KO, NKO, and CKO mice correspond well with the in vitro observations in that higher levels of the ACE substrates were observed when the processing domain was knocked out. This study highlights the vast extent of ACE promiscuity and provides a valuable platform for further investigations of ACE functionality.

Efferocytosis of apoptotic neutrophils by macrophages anchors the resolution of intestinal inflammation and is implicated in the pathogenesis of inflammatory bowel disease. We demonstrate that macrophage cyclooxygenase 2 potentiates efferocytosis capacity and facilitates efferocytosis-dependent macrophage reprogramming and intestinal epithelial repair.CONCLUSIONS: Macrophage COX2 potentiates efferocytosis capacity and efferocytosis-dependent reprogramming, facilitating macrophage intestinal epithelial repair capacity.

Background The toxigenic mold Stachybotrys has controversially been linked to idiopathic pulmonary hemorrhage and “sick building syndrome.” However, there are no previous clinical records of invasive stachybotryosis. Methods Sinus biopsy specimens from a 23-year-old male with refractory acute lymphocytic leukemia were obtained at 3 different time points during the patient’s hospitalization (139 days) and examined by histopathology and immunohistochemistry (IHC). Antifungal susceptibility testing and fungal speciation using multilocus sequence typing were performed. Results Hemorrhage, fungal germination, and hyphal growth were observed in the first sinus biopsy tissues. Areas with fungal growth tested positive for Stachybotrys by IHC. Fungal isolates were genotyped and identified as Stachybotrys chlorohalonata. The patient was cured from Stachybotrys sinusitis following sinus surgery and antifungal treatment. While a subsequent second sinus biopsy and a bronchoscopy showed no signs of fungal infection, a later, third sinus biopsy tested positive for Aspergillus calidoustus, a rare human pathogen. Conclusions Here, we report the first case of invasive S. chlorohalonata sinusitis that was surgically and medically cured but followed by invasive A. calidoustus sinusitis in the setting of refractory leukemia. Our findings emphasize the risk for unusual fungal infections in severely immunocompromised patients.