Mucorales species cause debilitating, life-threatening sinopulmonary diseases in immunocompromised patients and penetrating wounds in trauma victims. Common antifungal agents against mucormycosis have significant toxicity and are often ineffective. To evaluate treatments against mucormycosis, sporangiospores are typically used for in vitro assays and in pre-clinical animal models of pulmonary infections. However, in clinical cases of wound mucormycosis caused by traumatic inoculation, hyphal elements found in soil are likely the form of the inoculated organism. In this study, Galleria mellonella larvae were infected with either sporangiospores or hyphae of Rhizopus arrhizus and Lichtheimia corymbifera. Hyphal infections resulted in greater and more rapid larval lethality than sporangiospores, with an approximate 10–16-fold decrease in LD₅₀ of hyphae for R. arrhizus (p = 0.03) and L. corymbifera (p = 0.001). Liposomal amphotericin B, 10 mg/kg, was ineffective against hyphal infection, while the same dosage was effective against infections produced by sporangiospores. Furthermore, in vitro, antifungal susceptibility studies show that minimum inhibitory concentrations of several antifungal agents against hyphae were higher when compared to those of sporangiospores. These findings support using hyphal elements of Mucorales species for virulence testing and antifungal drug screening in vitro and in G. mellonella for studies of wound mucormycosis.

Traumatic brain injury (TBI) remains a significant public health concern, particularly among military personnel and contact sport athletes who are frequently exposed to repeated blast overpressure waves and mild concussive impacts, respectively. While moderate and severe TBIs have been extensively studied, the long-term neuroendocrine consequences of mild, repetitive brain trauma are poorly understood. In this study, we investigated the temporal dynamics of hypothalamic–pituitary–adrenal (HPA) axis dysregulation following repeated mild concussive head impacts and blast exposures using two clinically relevant rodent models. Male Sprague-Dawley rats were subjected to repeated mild concussive impacts using a modified weight drop model or repeated blast exposures using an advanced blast simulator. Plasma levels of adrenocorticotropic hormone (ACTH) and corticosterone were measured on days 1 and 30 post-injuries. Our findings revealed that repeated blast exposures induced elevation of plasma ACTH and corticosterone on days 1 and 30 post-blasts. After the repeated mild concussive impacts, increased plasma levels of corticosterone were observed on days 1 and 30, but ACTH levels were increased only on day 30. This study is among the first to directly compare neuroendocrine outcomes of repeated mild concussive impacts and blast exposures within a unified experimental framework. Our findings demonstrate distinct temporal trajectories of HPA axis dysregulation depending on injury type and highlight plasma levels of ACTH and corticosterone as potential biomarkers of subclinical brain trauma. These insights may inform early diagnostic approaches and therapeutic strategies aimed at mitigating long-term stress-related complications following mild traumatic brain injuries.

Wound-invasive fungal diseases (WIFDs), especially mucormycosis, have emerged as life-threatening infections during recent military combat operations. Many combat-relevant fungal pathogens are refractory to current antifungal therapy. Therefore, animal models of WIFDs are urgently needed to investigate new therapeutic solutions. Our study establishes combat-relevant murine models of wound mucormycosis using Rhizopus arrhizus and Lichtheimia corymbifera, two Mucorales species that cause wound mucormycosis worldwide. These models recapitulate the characteristics of combat-related wounds from explosions, including blast overpressure exposure, full-thickness skin injury, fascial damage, and muscle crush. The independent inoculation of both pathogens caused sustained infections and enlarged wounds. Histopathological analysis confirmed the presence of necrosis and fungal hyphae in the wound bed and adjacent muscle tissue. Semi-quantification of fungal burden by colony-forming units corroborated the infection. Treatment with liposomal amphotericin B, 30 mg/kg, effectively controlled R. arrhizus growth and significantly reduced residual fungal burden in infected wounds (p < 0.001). This study establishes the first combat-relevant murine model of wound mucormycosis, paving the way for developing and evaluating novel antifungal therapies against combat-associated WIFDs.

Background/Objectives: Blast-induced traumatic ocular injuries (bTOI) pose a significant risk to military and civilian populations, often leading to visual impairment or blindness. Retina, the innermost layer of ocular tissue consisting of photoreceptor and glial cells, is highly susceptible to blast injuries. Despite its prevalence, the molecular mechanisms underlying retinal damage following bTOI remain poorly understood, hindering the development of targeted therapies. Melatonin, a neuroprotective indoleamine with antioxidant, anti-inflammatory, and circadian regulatory properties, is synthesized in the retina and plays a crucial role in retinal health. Similarly, retina-specific genes, such as Rhodopsin, Melanopsin, and RPE65, are essential for photoreceptor function, visual signaling, and the visual cycle. However, their responses to blast exposure have not been thoroughly investigated. Methods: In this study, we utilized a ferret model of bTOI to evaluate the temporal expression of melatonin-synthesizing enzymes, such as tryptophan hydroxylase 1 and 2 (TPH1 and TPH2), Aralkylamine N-acetyltransferase (AANAT), and Acetylserotonin-O-methyltransferase (ASMT), and retina-specific genes (Rhodopsin, Melanopsin) and retinal pigment epithelium-specific 65 kDa protein (RPE65) at 4 h, 24 h, 7 days, and 28 days post-blast. Ferrets were exposed to tightly coupled blast overpressure waves using an advanced blast simulator, and retinal tissues were collected for quantitative polymerase chain reaction (qPCR) analysis. Results: The results revealed dynamic and multiphasic transcriptional responses. TPH1 and TPH2 exhibited significant upregulation at 24 h, followed by downregulation at 28 days, indicating blast-induced dysregulation of tryptophan metabolism, including melatonin synthesis. Similarly, AANAT and ASMT showed acute downregulation post-blast, with late-phase disruptions. Rhodopsin expression increased at 24 h but declined at 28 days, while Melanopsin and RPE65 demonstrated early upregulation followed by downregulation, reflecting potential disruptions in circadian regulation and the visual cycle. Conclusions: These findings highlight the complex regulatory mechanisms underlying retinal responses to bTOI, involving neuroinflammation, oxidative stress, and disruptions in melatonin synthesis and photoreceptor cell functions. The results emphasize the therapeutic potential of melatonin in mitigating retinal damage and preserving visual function.

The transient upregulation of cellular senescence within wound tissues has been demonstrated to be an important biological process facilitating efficient tissue repair. Dysregulation of this transient wound‐induced senescence response can result in impaired healing outcomes. Given the established age‐related decline in tissue regenerative capacity, we hypothesized that alterations in this senescence response contribute to the delayed healing of cutaneous wounds in aged individuals. Our investigation demonstrated a significant delay in the closure of full‐thickness dorsal skin wounds in aged mice compared to their young counterparts. Analysis of the wound microenvironment revealed a transient upregulation of senescence‐associated markers (p16, p21, senescence‐associated β‐galactosidase) and senescence‐associated secretory phenotype factors in the wound tissue of young mice, a response that was markedly attenuated in aged mice. Single‐cell RNA sequencing analysis of all cells isolated from day 6 wounds identified a distinct population of p16 ⁺ /p21 ⁺ /Ki67 ⁻ senescent fibroblasts in young mice, characterized by a transcriptional signature indicative of prohealing extracellular matrix production, a finding corroborated in human wound tissue from young donors. Crucially, in aged wounds, we observed a lower quantity of these senescent cells, a deficit compounded by a qualitative, age‐dependent shift in their function, moving away from beneficial extracellular matrix remodeling toward a more detrimental pro‐inflammatory state, which ultimately can contribute to delayed wound healing.