Curdlan, a β-1,3/1,6-glucan found in Alcaligenes faecalis (A. faecalis) wall, activates innate and humoral immunity. The aim of this study is to evaluate whether pretreated rats with A. faecalis A12C could prevent sepsis disturbances and identify the immunomodulatory mechanisms involved. Experiments occurred in two stages: a survival study with 16 rats randomly divided into septic (SC) (n = 8) and septic pretreated (SA) (n = 8) groups and 45 rats divided into four groups: healthy (AGUSAN) (n = 9), septic (AGUIC) (n = 13), septic pretreated (AGUIA) (n = 14), and healthy pretreated (AGUSTO) (n = 9). Sepsis was induced by cecal ligation and puncture after 30 days of A. faecalis A12C pretreatment or without. SA group had a higher survival rate of 58% vs. 16% for SC group (P < 0.05). Overall, AGUIA showed better status than AGUIC (P < 0.01). Higher monocytosis was found in AGUIA and AGUSTO vs. AGUIC and AGUSAN, respectively (P < 0.05). A gradual increase in curdlan fecal concentration was observed in AGUIA during pretreatment. Fecal concentrations of Escherichia coli significantly decreased in AGUIA and AGUSTO. Bacterial load in urine, peritoneal lavage fluid (PLF), and bronchoalveolar lavage fluid (BALF) decreased (P < 0.05) in AGUIA vs. AGUIC. Finally, lower inflammation was observed in serum, BALF, and PLF, with reduced IL-6, IL-10, IL-1β, and TNF-α, along with less damage in lungs and peritoneum in AGUIA vs. AGUIC. These findings suggest the connection between curdlan—produced by A. faecalis A12C—with the immune system and the reduction in severity of experimental sepsis.

Sepsis is characterized by a dysregulated host response to infection; this can lead to multiorgan dysfunction where liver and kidneys play a key role. This study evaluated whether long-term oral administration of A12C modulates hepatic and renal homeostasis under basal conditions and during polymicrobial sepsis. Forty-five male Sprague–Dawley rats were allocated to healthy control (SAN), healthy A12C-treated (STO), septic control (IC), or septic A12C-treated (IA) groups. A12C was administered in drinking water at 6×10⁸ CFU/mL for 30 days, and sepsis was induced by caecal ligation and puncture (CLP). Gene expression, protein abundance, antioxidant enzyme activities, and histopathological alterations were evaluated in liver and kidney. Under basal conditions, A12C reduced hepatic Tlr4 and Tgfb1 expression and TLR4, ICAM-1, and SOD2 protein abundance, whereas renal Tnf and Icam1 expression and SOD and GRd activities increased. During sepsis, A12C-treated rats showed lower hepatic expression of Tnf, Il6, Ccl2, Icam1, and Nos2, together with increased SOD1 protein abundance. In kidney, A12C reduced Tlr4, Il6 and Icam1 expression and increase CAT, GPx, and GRd activities. Reduced expression of several inflammatory and endothelial mediators was detected in both organs and a marked enhancement of renal antioxidant defences during sepsis. The present results support the potential of A12C to improve the host response to sepsis and limit sepsis-associated organ dysfunction, possibly through a preconditioning-like mechanism.

Microbial β-(1→3)-glucans are polysaccharides of biological and technological in-terest whose production depends strongly on strain and culture conditions. This study characterized the temporal relationship between bacterial growth and aniline-blue re-activity in Alcaligenes faecalis A12C under growth and fermentation conditions. Growth, viability, and β-(1→3)-glucan-associated signals were monitored over 96 h using spec-trophotometric, microbiological, and microscopic approaches. In growth culture me-dium (GCM), OD600 increased after 24–30 h and reached approximately 2.4 at 72 h, coinciding with the highest viable count (2.49 × 10²¹ CFU/mL). Aniline-blue coloration became clearly detectable after approximately 30 h and persisted through 96 h, when microscopy showed blue staining associated with bacterial cells. In fermentation culture medium (FCM), OD600 increased progressively to approximately 2.8 at 96 h, whereas viable counts followed a distinct temporal profile. Aniline-blue reactivity increased during early fermentation and remained stable at an A610 of approximately 1.0 from 24 h onward. The divergence among OD600, viable counts, and aniline-blue reactivity in-dicates that bacterial proliferation and development of the aniline-blue-reactive signal followed distinct temporal patterns. These findings characterize this temporal rela-tionship in A12C cultures, although chemical and structural characterization is required to determine whether the detected polymer corresponds to curdlan.

Major depressive disorder pathophysiology involves complex gut-brain axis interactions, yet the systemic non-neurochemical impacts of selective serotonin reuptake inhibitors re-main poorly defined. This study evaluated the multidimensional effects of chronic fluoxe-tine administration in Sprague-Dawley rats. Male rats received fluoxetine (10 mg/kg/day) or water for 60 days, followed by behavioral phenotyping, fecal microbiological quantifi-cation, serum biochemistry, complete blood count analysis, and immunohistochemical assessment of the immediate-early gene product c-Fos (cellular proto-oncogene protein) in the striatum. Fluoxetine treatment significantly reduced immobility time in the forced swim test, whereas object recognition memory deteriorated without alterations in anxie-ty-like behavior. Pharmacological intervention markedly depleted fecal bacterial popula-tions and significantly decreased serum vitamin D concentrations. Hematologically, treated animals exhibited significant reductions in total leukocytes, red blood cells, and platelets, alongside elevated hematocrit and mean corpuscular volume. Concurrently, c-Fos-positive neuronal activation increased significantly within the striatal nucleus ac-cumbens. In conclusion, chronic fluoxetine exposure induces profound systemic disrup-tion, altering gut microbial homeostasis, depleting vitamin D, and modulating peripheral blood profiles while enhancing central striatal neuronal plasticity. These findings under-score the necessity of monitoring gut-brain axis integrity during prolonged antidepressant therapy.

Since ancient times, sepsis has been a potentially lethal complication, and it continues to be a significant cause of illness and death worldwide, which makes it necessary to find new approaches an...