Biology subjects

Miranda, I. C.

Publications and source records attributed to Miranda, I. C..

3 recordsLinked to original sources

bioRxiv2026

Microbiome-Dependent Protection Against Corynebacterium bovis-Associated Hyperkeratosis in Nude Mice (Mus musculus)

Corynebacterium bovis, the cause of Corynebacterium-associated hyperkeratosis (CAH), is an important pathogen in immunocompromised mice that is difficult to eliminate and can confound research outcomes. We recently observed that CAH severity varies among outbred athymic nude mouse stocks, but the relative contributions of host genetics and the microbiome remain unclear. We hypothesized that disease course and severity vary based on host genetic stock and/or microbiome composition. Three nude mouse stocks were rederived into the axenic state and either monoinfected with a pathogenic C. bovis isolate (104; CFU) or given sterile media (n=6/group). Axenic mice were also reassociated with their source microbiome or microbiomes from three other stocks with known differences in CAH severity, then inoculated with C. bovis (n=6) or sterile media (n=2). In a separate experiment, one axenic stock was used to assess the role of C. amycolatum via monoinfection, monoinfection followed by C. bovis challenge, or addition to a nonprotective microbiome followed by C. bovis challenge. Mice were monitored daily for 21 days and scored for skin lesions (0-5). C. bovis monoinfected mice developed disease comparable in severity and timing to conventionally raised controls. Notably, reassociation with Vendor A2s microbiome prevented clinical lesions and reduced histopathologic changes across all stocks. While C. amycolatum as a monoinfection did not cause disease nor reduce disease severity following C. bovis challenge, it delayed the onset and lowered peak scores when added to a non-protective microbiome. These findings demonstrate that C. bovis can cause CAH as a monoinfection, that both host genetics and microbiome composition influence disease progression, and, together with prior work, support its role as the etiologic agent consistent with Kochs postulates. Identifying protective microbiome constituents may inform strategies to reduce disease burden in susceptible mice.

microbiology↗

bioRxiv2023

WNK1 enforces macrophage lineage fidelity

The appropriate development of macrophages, the bodys professional phagocyte, is essential for organismal development, especially in mammals. This dependence is exemplified by the observation that loss-of-function mutations in colony stimulating factor 1 receptor (CSF1R) results in multiple tissue abnormalities owing to an absence of macrophages. Despite this importance, little is known about the molecular and cell biological regulation of macrophage development. Here, we report the surprising finding that the chloride-sensing kinase With-no-lysine 1 (WNK1) is required for development of tissue-resident macrophages (TRMs). Myeloid-specific deletion of Wnk1 resulted in a dramatic loss of TRMs, disrupted organ development, systemic neutrophilia, and mortality between 3 and 4 weeks of age. Strikingly, we found that myeloid progenitors or precursors lacking WNK1 not only failed to differentiate into macrophages, but instead differentiated into neutrophils. Mechanistically, the cognate CSF1R cytokine macrophage-colony stimulating factor (M-CSF) stimulates macropinocytosis by both mouse and human myeloid progenitors and precursor cells. Macropinocytosis, in turn, induces chloride flux and WNK1 phosphorylation. Importantly, blocking macropinocytosis, perturbing chloride flux during macropinocytosis, and inhibiting WNK1 chloride-sensing activity each skewed myeloid progenitor differentiation from macrophages into neutrophils. Thus, we have elucidated a role for WNK1 during macropinocytosis and discovered a novel function of macropinocytosis in myeloid progenitors and precursor cells to ensure macrophage lineage fidelity. Highlights- Myeloid-specific WNK1 loss causes failed macrophage development and premature death - M-CSF-stimulated myeloid progenitors and precursors become neutrophils instead of macrophages - M-CSF induces macropinocytosis by myeloid progenitors, which depends on WNK1 - Macropinocytosis enforces macrophage lineage commitment

immunology↗

bioRxiv2022

Establishing the Median Infectious Dose (ID50) and Characterizing the Clinical Manifestations of Mouse, Rat, Cow, and Human Corynebacterium bovis Isolates in Select Immunocompromised Mouse Strains

Corynebacterium bovis (Cb), the etiology of hyperkeratotic dermatitis in various immunocompromised mouse strains, significantly impacts research in which infected mice are used. Although Cb has been isolated from a variety of species, including mice, rats, cows, and humans, little is known about the differences in the infectivity and clinical disease in mice associated with unique isolates. The infectious dose yielding colonization of 50% of the exposed population (ID50) and any associated clinical disease was determined for mouse (n=3), rat (n=1), cow (n=1), and human (n=2) Cb isolates in athymic nude mice (Hsd:Athymic Nude-Foxn1nu). The same investigations were undertaken comparing 2 of these murine isolates in 2 furred immunocompromised mouse strains (NSG [NOD.Cg-PrkdcscidIl2rgtm1Wjl/Sz] and NSG-S [NOD.Cg-PrkdcscidIl2rgtm1WjlTg(CMV-IL3,CSF2,KITLG)1Eav/MloySzJ]). To determine the ID50, mice (n=6/dose; 3 of each sex) were inoculated topically with 1 to 108 bacteria (10-fold increments) of each Cb isolate. Mice were scored (0 to 5) daily based on the severity of clinical signs for 14 days. On day 7 and 14 post-inoculation (PI), buccal and dorsal skin swabs were evaluated by aerobic culture to determine infection status. The mouse isolates yielded a lower ID50 (58 to 1,000 bacteria) as compared to the bovine (6,460 to 7,498 bacteria) and rat (10,000 bacteria) Cb isolates. Mice were not colonized and disease did not result when inoculated with human isolates. Mouse isolates produced varying clinical disease severity in nude mice (max score/isolate: 0 to 5). Despite significant immunodeficiency, furred NSG and NSG-S mice required a considerably higher (1,000- to 3,000-fold) inoculum to become colonized as compared to athymic nude mice. Once colonized, clinically detectable hyperkeratosis did not develop in these strains until 18 to 22 days PI. In contrast, in athymic nude mice that developed clinically detectable disease, hyperkeratosis was observed 6 to 14 days PI. In conclusion, there are significant differences in Cbs ID50, disease course, and severity between Cb isolates and among immunodeficient mouse strains.

microbiology↗