Administration Of Doxycycline Research Articles

Delayed effects of antibiotic therapy in endotoxinemia

BACKGROUND: Nowadays, due to the increasing number of infectious and inflammatory diseases, the problem of the use of antibacterial drugs becomes especially important. As a result of the action of toxins, inflammatory processes can affect the central nervous system with the subsequent development of neuroinflammation. Activation of neuroinflammation leads to dysregulation of many physiological functions. These negative appearances can be observed even after a long period. It is known that doxycycline is a tetracycline-type antibiotic, which is able to penetrate the blood-brain barrier and has anti-inflammatory activity. AIM: The aim of this study was to investigate the nature of delayed physiological changes in rats against the background of administration of the antibacterial drug doxycycline in the LPS-induced model of neuroinflammation. MATERIALS AND METHODS: Four groups of Wistar rats, 10 males in each group, were used in the experiment. The first group was injected once intraperitoneally with physiological solution, the second group — with lipopolysaccharide (1 mg/kg). Animals of the third and fourth groups received intragastrically doxycycline solution (25 mg/kg) daily for two weeks. On the 15th day of the experiment, rats from the fourth group were injected with lipopolysaccharide (1 mg/kg). Body weight of animals, mass coefficients of immunocompetent organs, as well as behaviour and motor activity of rats in the “Open Field” test were evaluated at several time points. RESULTS: It was shown that systemic injection of lipopolysaccharide led to an increase in the mass coefficients of spleen, kidneys and adrenal glands compared to the group of animals receiving doxycycline beforehand. These changes were noted 48 h and 2 months after the injection of endotoxin. In the “Open Field” test, animals that were injected with doxycycline and lipopolysaccharide showed no violations of motor activity and research behavior, unlike the group that received only lipopolysaccharide. CONCLUSIONS: It can be assumed that the physiological effects of doxycycline in the lipopolysaccharide-induced model of neuroinflammation revealed at early and late terms are not limited to the antibacterial effect of the drug and are mediated by anti-inflammatory and potential neuroprotective effects on the central nervous system.

Adherence to Hygiene Protocols and Doxycycline Therapy in Ameliorating Lymphatic Filariasis Morbidity in an Endemic Area Post-Interruption of Disease Transmission in Ghana.

Filarial lymphedema (LE) remains a significant global problem despite the progress made toward elimination of lymphatic filariasis (LF). In Ghana, the main approach to LF is preventive chemotherapy, but this has minimal impact on individuals who have already developed LE. In 2018-2020, a 24-month randomized, double-blind, placebo-controlled trial was conducted to evaluate the efficacy of stringent hygiene measures using the Essential Package of Care with or without additional administration of doxycycline (DOX) to improve filarial leg LE. This study enrolled 356 participants with LE stages 1-3 from two districts in the Upper East Region of Ghana. In addition to regular training on appropriate care for their affected legs, participants were randomized to receive 6 weeks of either 200 mg/day DOX (n = 117), 100 mg/day DOX (n = 120), or matching placebo (n = 119). Participants were seen every 2 months, with clinical measurements done at 6, 12, 18, and 24 months to assess the status of affected legs. There was a trend toward later appearance of acute attacks after DOX, but surprisingly, DOX showed no effect on LE stage progression. In all groups, leg LE improvement was more common (DOX 200 mg: n = 23 [20%]; DOX 100 mg: n = 23 [19.5%]; placebo: n = 32 [27.4%]) than LE worsening (DOX 200 mg: n = 2 [1.7%]; DOX 100 mg: n = 3 [2.5%]; placebo: n = 2 [1.7%]). Overall, these data show a strong benefit from adherence to a strict hygiene protocol, with some added potential benefit for DOX in preventing acute attacks.

Two complicated cases of severe scrub typhus, eschar- a non-negligible sign: Case reports and literature review.

Scrub typhus is a mite-borne, acute febrile disease caused by Orientia tsutsugamushi. The endemic areas of scrub typhus are expanding, both globally and in China. Patients who are not treated promptly, are likely to die of multiple organ dysfunction syndrome. Case I A 61-year-old female patient complained of sudden chest tightness and shortness of breath accompanied by fever for 6 days. Case II A 54-year-old male patient complained of fever and cough for 4 days and renal insufficiency for 2 days. Scrub typhus, multiple organ dysfunction syndrome. After the definite diagnosis, both patients were treated with doxycycline and various organ supports. The patient in case I was ultimately not salvageable. The patient in case II was successfully cured by the prompt administration of doxycycline along with continuous renal replacement therapy. With early diagnosis and treatment, patients can completely recover. Eschar, a characteristic sign of scrub typhus, is often overlooked, leading to delayed diagnosis and regrettable outcomes.

A Case Report: Treatment of Anaplasmosis and Ectoparasitic Infestation in Mixed-Breed Golden Retriever Dog

Anaplasmosis is a disease in dogs caused by intracellular gram-negative bacteria belonging to the Anaplasmataceae family. A 6-month-old mixed-breed golden retriever was examined at the Laboratory of Veterinary Internal Medicine, Faculty of Veterinary Medicine, Udayana University, with complaints of itching, tick infestation, weakness, and decreased appetite. The clinical examination revealed pale mucous membranes in the mouth and eye conjunctiva, as well as an infestation of Rhipicephalus ticks on the skin. Routine hematological examination indicated the presence of anemia and thrombocytopenia. Blood smear examination confirmed the presence of Anaplasma sp. Treatment was provided in a causative and supportive manner. Causative therapy involved the administration of doxycycline at a dose of 10 mg/kg body weight orally for twenty-eight days, ivermectin at a dose of 0.2 mg/kg body weight injected subcutaneously every two weeks for four weeks. Supportive therapy included the daily administration of Fufang E'jiao Jiang ®(Dong E Ejiao Co, Ltd., Shandong, China) at 2 ml/day and Sangobion® (PT. Merck Tbk, Jakarta, Indonesia) at one tablet per day for fourteen days. Treatment with doxycycline, ivermectin, Fufang E'jiao Jiang® (Dong E Ejiao Co, Ltd., Shandong, China), and Sangobion® (PT. Merck Tbk, Jakarta, Indonesia) resulted in a positive outcome for the dog, with improved activity, hair growth, good appetite, and the absence of ticks.

A "suicide" BCG strain provides enhanced immunogenicity and robust protection against Mycobacterium tuberculosis in macaques.

Intravenous (IV) BCG delivery provides robust protection against Mycobacterium tuberculosis (Mtb) in macaques but poses safety challenges. Here, we constructed two BCG strains (BCG-TetON-DL and BCG-TetOFF-DL) in which tetracyclines regulate two phage lysin operons. Once the lysins are expressed, these strains are killed in immunocompetent and immunocompromised mice yet induced similar immune responses and provided similar protection against Mtb challenge as wild type BCG. Lysin induction resulted in release of intracellular BCG antigens and enhanced cytokine production by macrophages. In macaques, cessation of doxycycline administration resulted in rapid elimination of BCG-TetOFF-DL. However, IV BCG-TetOFF-DL induced increased pulmonary CD4 T cell responses compared to WT BCG and provided robust protection against Mtb challenge, with sterilizing immunity in 6 of 8 macaques, compared to 2 of 8 macaques immunized with WT BCG. Thus, a "suicide" BCG strain provides an additional measure of safety when delivered intravenously and robust protection against Mtb infection.

The effect of early administration of antibiotics or feeding a diet containing coccidiostats on the level of their accumulation in liver and the redox status of turkeys

Early administration of antibiotics may worsen the functioning of the turkeys’ antioxidant system. It was also assumed that the longer the time of administration of an antibiotic, e.g. a coccidiostat, the greater the risk of its accumulation in the liver. The study aimed to determine whether early administration of antibiotics or feeding a diet containing coccidiostats causes accumulation in the liver and whether it affects the deterioration of the antioxidant system, and whether preventive vaccinations can intensify it. A total of 3 080 female turkeys were randomly allocated to eight groups. The experiment had a two-factorial design, with four treatments (C, M, E, D) and two groups of birds (vaccinated +, unvaccinated −). The C group did not receive the coccidiostat or antibiotics. Group M was administered monensin at 90 mg/kg feed for 56 days of life. Group E received enrofloxacin at 10 mg/kg BW, and group D received doxycycline at 50 mg/kg BW, added to drinking water, for the first 5 days of life. One-day-old turkeys from groups C+, M+, E+, and D+ were administered live-attenuated vaccines against turkey rhinotracheitis and Newcastle disease by coarse spray; 28-day-old birds were administered a subcutaneously injected inactivated vaccine against Ornithobacterium rhinotracheale. Turkeys from groups C-, M-, E-, and D- were not vaccinated. It was determined that as a result of administration of enrofloxacin or doxycycline until the 5th day of life, biotransformation of these antibiotics occurred in the liver until the 56th day of life of the turkeys, which was confirmed by their lower level than the Maximum Residue Level. Because the concentration of monensin in the liver of turkeys gradually increased with the extension of the time of its administration in the diet, it is probable that discontinuing its addition a day before the slaughter of birds will result in the presence of this coccidiostat in the liver of turkeys. Despite the accumulation of monensin in the liver of turkeys, this coccidiostat did not increase oxidative reactions in the organism of turkeys. Vaccination of turkeys can reduce oxidative reactions and apoptosis in the body. However, the effect of the redox system reaction is different immediately after vaccination, which is due to the mechanism of action of the immune system. If it is necessary to administer an antibiotic in the early rearing period, the effects of doxycycline on the organism’s immunity including antioxidant defence will be less severe than those of enrofloxacin.

Bioactive Glial-Derived Neurotrophic Factor from a Safe Injectable Collagen-Alginate Composite Gel Rescues Retinal Photoreceptors from Retinal Degeneration in Rabbits.

The management of vision-threatening retinal diseases remains challenging due to the lack of an effective drug delivery system. Encapsulated cell therapy (ECT) offers a promising approach for the continuous delivery of therapeutic agents without the need for immunosuppressants. In this context, an injectable and terminable collagen-alginate composite (CAC) ECT gel, designed with a Tet-on pro-caspase-8 system, was developed as a safe intraocular drug delivery platform for the sustained release of glial-cell-line-derived neurotrophic factor (GDNF) to treat retinal degenerative diseases. This study examined the potential clinical application of the CAC ECT gel, focusing on its safety, performance, and termination through doxycycline (Dox) administration in the eyes of healthy New Zealand White rabbits, as well as its therapeutic efficacy in rabbits with sodium-iodate (SI)-induced retinal degeneration. The findings indicated that the CAC ECT gel can be safely implanted without harming the retina or lens, displaying resistance to degradation, facilitating cell attachment, and secreting bioactive GDNF. Furthermore, the GDNF levels could be modulated by the number of implants. Moreover, Dox administration was effective in terminating gel function without causing retinal damage. Notably, rabbits with retinal degeneration treated with the gels exhibited significant functional recovery in both a-wave and b-wave amplitudes and showed remarkable efficacy in reducing photoreceptor apoptosis. Given its biocompatibility, mechanical stability, controlled drug release, terminability, and therapeutic effectiveness, our CAC ECT gel presents a promising therapeutic strategy for various retinal diseases in a clinical setting, eliminating the need for immunosuppressants.

Effect of Doxycycline on Clinical Outcomes in Patients with Ischemic Stroke

Background and Objective: Stroke is the second leading cause of disability and mortality across the globe. The present study aimed to assess the effect of doxycycline on clinical outcomes of patients with ischemic stroke. Materials and Methods: In this double-blind clinical trial, 60 patients with ischemic stroke were selected in the first 24 hours of post-stroke and randomly assigned to two groups: intervention and control. In the intervention group, patients received 100 mg of doxycycline every 12 hours for seven days in addition to standard treatments. Both groups were followed up before the intervention, on days 7, 30, and 90 after the treatment in terms of the severity of stroke clinical outcomes using National Institutes of Health Stroke Scale (NIHSS) and Modified Rankin Scale (mRS) tests. Results: The mean age of patients in the intervention and control groups were 68.33±12.15 and 67.40±9.99 years (P>0.05). No significant difference was observed between the intervention and control groups in terms of NIHSS and mRS scores at baseline and on the seventh day. Nonetheless, in the intervention group, the NIHSS score on days 30 (P=0.007) and 90 (P<0.001), as well as the mRS score on days 30 (P=0.009) and 90 (P<0.01) was significantly less than the control group. Conclusion: In ischemic stroke, the administration of doxycycline 100 mg every 12 hours for seven days is safe, reduces neurological disorders, and improves the clinical outcome of patients within one to three months after the treatment.

Doxycycline pharmacokinetics and tissue depletion in striped catfish (Pagasianodon hypophthalmus) after oral administration.

The pharmacokinetics and residue depletion of doxycycline (DOX) in striped catfish (Pagasianodon hypophthalmus) after oral dosage were investigated. The pharmacokinetic experiment was conducted in an aquarium, while the experiment of residue depletion was performed in both an aquarium and earth ponds. Medicated feed was administered orally using the gavage method at a dosage of 20 mg/kg body weight. Blood, liver, and kidney from medicated fish samples were collected. In the depletion experiments, fish were fed medicated feed for five consecutive days at a dosage of 20 mg/kg body weight, with samples collected during and after medication. The concentrations of DOX were quantified using an LC-MS/MS system. The pharmacokinetics parameters of DOX in striped catfish included the absorption rate constant (ka), absorption half-life (T1/2abs), maximal plasma concentration (Cmax), time to maximal plasma concentration (Tmax), and area under the plasma concentration-time curve from time 0 to 96 h (AUC0-96 h) which were 0.12 h-1, 5.68 h, 1123.45 ng/mL, 8.19 h, and 25,018 ng/mL/h, respectively. Residue depletion results indicated that the withdrawal times of DOX in muscle (with skin) from fish kept in the aquarium were slightly longer than that in fish raised in earth ponds, corresponding to 194 degree-days compared with 150 degree-days. In conclusion, administration of DOX at the dosage of 20 mg/kg body weight can be used for treatment of bacterial infections in striped catfish, and a withdrawal time of 5 days at 29.4°C will ensure consumer food safety due to the rapid depletion of DOX from muscle and skin.

Drug Prescription Pattern for Leptospirosis and Association with Outcome: Observations from a Tertiary Care Center

Background: Leptospirosis, an infection of the tropics, caused by helical spirochetes, Genus Leptospira. For the first time, this study examines the pattern of antibiotic prescription for leptospirosis and its association with outcome. Materials and Methods: This was a hospital-based retrospective study. A total of 227 adults diagnosed and treated for leptospirosis during the study period of January 2013 to December 2018 were included in the study. Information on gender, age, admission details, outcome, inpatient days, and antibiotics used was collected from the patients’ records and analyzed. Results: Around 75% of the leptospirosis patients were male and majority (70.4%) of the patients were from the age group of 31–60 years. Most of the patients (43.6%) were admitted for 6–10 days; 27.3% of the patients were admitted in the intensive care unit (ICU) and the mortality rate was 7.49%. Ceftriaxone was the most (53.3%) prescribed intravenous antimicrobial, followed by piperacillin–tazobactum (32.6%), and among oral antimicrobials, doxycycline was prescribed in 37.4% of the patients. Penicillin was administered to 44 patients with mild disease and all survived. Among the Ceftriaxone and piperacillin–tazobactum prescribed, 26.5% (32/121) and 35% (26/74) were admitted in ICU, respectively. Among the patients with severe disease, who succumbed to leptospirosis, ceftriaxone, and piperacillin–tazobactam were prescribed in 8.28% and 4.05%, respectively. Conclusion: The pattern of antibiotics prescribed in the study center was in accordance with the standard guidelines. The prescriptions were predominantly penicillin and doxycycline in early conditions while ceftriaxone and piperacillin–tazobactum were administered in advance/severe conditions. Patients with mild disease recovered with penicillin, while in advanced disease, even administration of third cephalosporins and doxycycline had a poor prognosis leading to death of the patients, indicating the need for early diagnosis and treatment to be important to prevent mortality.

Ocular rosacea without facial erythema involvement manifesting as bilateral multiple recurrent chalazions: A case report

BACKGROUND In addition to the non-specific symptomatology of ocular rosacea, currently, there are no reliable diagnostic tests for the disease, which may lead to its misdiagnosis. Here, we report a case of ocular rosacea presenting with multiple recurrent chalazion on both eyelids. CASE SUMMARY A 63-year-old female patient presented with multiple chalazion and dry eyes in both eyes, with no facial erythema. Initial management done were application of steroid eye ointment on both eyelids, hot compresses, and eyelid margin cleaning; noting that there was no relief of symptoms. Surgical excision of the chalazion was done on both eyes, however, bilateral recurrence occurred post-operatively. The pathological studies showed infiltration of a small amount of fibrous tissue with many chronic inflammatory cells. Immunohistochemistry studies were positive for LL-37. Resolution of the chalazion occurred after oral administration of doxycycline and azithromycin. CONCLUSION Our findings show that ophthalmologists should recognize the ocular manifestations of skin diseases.

Delay in the diagnosis of Brucella abortus bacteremia in a nonendemic country: a case report

BackgroundIt is challenging to diagnose brucellosis in nonendemic regions because it is a nonspecific febrile disease. The accurate identification of Brucella spp. in clinical microbiology laboratories (CMLs) continues to pose difficulties. Most reports of misidentification are for B. melitensis, and we report a rare case of misidentified B. abortus.Case presentationA 67-year-old man visited an outpatient clinic complaining of fatigue, fever, and weight loss. The patient had a history of slaughtering cows with brucellosis one year prior, and his Brucella antibody tests were negative twice. After blood culture, the administration of doxycycline and rifampin was initiated. The patient was hospitalized due to a positive blood culture. Gram-negative coccobacilli were detected in aerobic blood culture bottles, but the CML's lack of experience with Brucella prevented appropriate further testing. Inaccurate identification results were obtained for a GN ID card of VITEK 2 (bioMérieux, USA) and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI–TOF MS) using a MALDI Biotyper (Bruker, Germany). The strain showed 100.0% identity with Brucella spp. according to 16S rRNA sequencing. MALDI–TOF MS peaks were reanalyzed using the CDC MicrobeNet database to determine Brucella spp. (score value: 2.023). The patient was discharged after nine days of hospitalization and improved after maintaining only doxycycline for six weeks. The isolate was also identified as Brucella abortus by genomic evidence.ConclusionAutomated identification instruments and MALDI–TOF MS are widely used to identify bacteria in CMLs, but there are limitations in accurately identifying Brucella spp. It is important for CMLs to be aware of the possibility of brucellosis through communication with clinicians. Performing an analysis with an additional well-curated MALDI–TOF MS database such as Bruker security-relevant (SR) database or CDC MicrobeNet database is helpful for quickly identifying the genus Brucella.

Poor Decision Making and Sociability Impairment Following Central Serotonin Reduction in Inducible TPH2-Knockdown Rats.

Serotonin is an essential neuromodulator for mental health and animals' socio-cognitive abilities. However, we previously found that a constitutive depletion of central serotonin did not impair rat cognitive abilities in stand-alone tests. Here, we investigated how a mild and acute decrease in brain serotonin would affect rats' cognitive abilities. Using a novel rat model of inducible serotonin depletion via the genetic knockdown of tryptophan hydroxylase 2 (TPH2), we achieved a 20% decrease in serotonin levels in the hypothalamus after three weeks of non-invasive oral doxycycline administration. Decision making, cognitive flexibility, and social recognition memory were tested in low-serotonin (Tph2-kd) and control rats. Our results showed that the Tph2-kd rats were more prone to choose disadvantageously in the long term (poor decision making) in the Rat Gambling Task and that only the low-serotonin poor decision makers were more sensitive to probabilistic discounting and had poorer social recognition memory than other low-serotonin and control individuals. Flexibility was unaffected by the acute brain serotonin reduction. Poor social recognition memory was the most central characteristic of the behavioral network of low-serotonin poor decision makers, suggesting a key role of social recognition in the expression of their profile. The acute decrease in brain serotonin appeared to specifically amplify the cognitive impairments of the subgroup of individuals also identified as poor decision makers in the population. This study highlights the great opportunity the Tph2-kd rat model offers to study inter-individual susceptibilities to develop cognitive impairment following mild variations of brain serotonin in otherwise healthy individuals. These transgenic and differential approaches together could be critical for the identification of translational markers and vulnerabilities in the development of mental disorders.

Drug induced bullous fixed drug eruption: a case report

Bullous fixed drug eruption, which is a cutaneous adverse drug reaction, is commonly seen with antimicrobials and analgesics. Bullous drug eruptions are infrequent, but because they pose a challenge both to affected patients and to treating physicians, they are considered to be the most severe cutaneous adverse reactions (SCAR). It is important to recognize these conditions and to differentiate them from other clinical entities involving blister formation. There may be early signs and symptoms that indicate a severe bullous drug eruption even before blisters and erosions of the skin and mucous membranes become obvious. Once the diagnosis is suspected, appropriate diagnostic procedures and adequate management must be initiated. The latter includes identification of the potentially inducing drug, although it should be taken into account that not all cases of bullous eruptions are drug-induced. In cases with drug causality the potentially culprit agent must be withdrawn, while in cases with other aetiology the underlying condition, e.g. an infection, must be treated appropriately. In addition to best supportive care, immunomodulating therapy may be considered. Here we report 64-year-old male with bullous fixed drug eruptions due to doxycycline administration.

Gastrointestinal response to the early administration of antimicrobial agents in growing turkeys infected with Escherichia coli

This study investigated the effects of the early administration of enrofloxacin (E) or doxycycline (D) for the first 5 consecutive days of life, or the continuous administration of the coccidiostat monensin (M) throughout the rearing period on gastrointestinal function in turkeys infected with avian pathogenic Escherichia coli (APEC) in an early or later stage of rearing. Experiment 1 lasted 21 d, and turkeys in groups E, D, and M were infected with APEC on d 15. Experiment 2 lasted 56 d, and it had a factorial arrangement of treatments where birds in groups E, D, and M were infected with APEC on d 15 or d 50. In both experiments, control groups (C) consisted of infected and uninfected birds without antibiotic or coccidiostat administration. On d 21 (Experiment 1) and d 56 (Experiment 2), 8 birds from each subgroup were killed, and the ileal and cecal digesta were sampled to analyze the activity of bacterial enzymes and the concentrations of short-chain fatty acids (SCFA). The experimental treatments did not affect the final body weight or body weight gain of birds. Both experiments demonstrated that APEC contributed to an increase in ammonia levels of the cecal digesta (means from 2 experiments: 0.311 vs. 0.225 mg/g in uninfected birds) and ileal pH (6.79 vs. 6.00) and viscosity (2.43 vs. 1.83 mPa⋅s). Moreover, the E. coli challenge enhanced the extracellular activity of several cecal bacterial enzymes, especially in older turkeys infected with APEC in a later stage of life. The continuous administration of monensin throughout the rearing period resulted in a weaker gastrointestinal response in older birds, compared with the other 2 antibiotics administered for the first 5 d of life. The results of the study are inconclusive as both desirable and undesirable effects of preventive early short-term antibiotic therapy were observed in turkeys, including normalization of ileal viscosity and cecal ammonia concentration (positive effect), and disruption in cecal SCFA production (negative effect).

Abstract 164: Genetic elimination of β-catenin using a doxycycline-regulated GEM model fails to restore checkpoint blockade efficacy due to persistent M2-like macrophages

Abstract Response to checkpoint blockade immunotherapy (CBI) is not universal, partly due to a wide variation in baseline immune cell infiltration in the tumor microenvironment (TME). One mechanism contributing to this variability is tumor cell-intrinsic activation of the β-catenin signaling pathway, which has previously been shown to result in a non-T cell-inflamed TME. Constitutive β-catenin signaling resulted in reduced Batf3-lineage dendritic cell (cDC1) recruitment, leading to reduced T cell activation and infiltration and loss of anti-CTLA-4+anti-PD-L1 therapeutic efficacy. Efforts to target the Wnt/β-catenin pathway to enhance immune responses in β-catenin-active tumors have seen limited success. A genetic experiment eliminating β-catenin expression after establishment of a non-T cell-inflamed TME might illustrate the maximal biologic effect that could be expected with blockade of the pathway. We developed a genetically engineered mouse (GEM) model that allows for dynamic regulation of β-catenin on and off. This model employs tyrosinase-driven tamoxifen-regulated Cre-recombinase to activate the BRAF V600E oncogene and delete the tumor suppressor gene PTEN, along with a transactivator for doxycycline-regulated expression of a non-degradable β-catenin. Topical application of 4-hydroxytamoxifen resulted in melanoma formation, and administration of doxycycline resulted in robust nuclear expression of melanocyte-specific β-catenin compared to non-treated controls. This was accompanied by a significant reduction in CD3+ T cell infiltration within the TME, confirming the link between active β-catenin signaling and T cell exclusion. Discontinuing doxycycline treatment led to complete reduction of nuclear β-catenin expression in the tumor cells within seven days and a substantial return of CD3+ T cells into the TME. However, despite the re-infiltration of CD3+ T cells, the tumors previously expressing β-catenin (ex-β-catenin tumors) did not regain therapeutic responsiveness to anti-CTLA-4+anti-PD-L1. Single cell RNA sequencing of the ex-β-catenin tumors indicated the presence of an immunosuppressive-like macrophage population, characterized by the expression of Ccl8, Gas6 and Cd163. This finding suggests that the prior presence of β-catenin may induce long-lasting changes in the TME that suppress the immune response even after β-catenin levels are reduced. These data corroborate previous findings on the role of β-catenin in modulating the immunological landscape of melanoma and extend it by demonstrating the long-term persistence of immune evasion by suppressive myeloid cells even after β-catenin signaling is eliminated. These insights have implications for clinical strategies aiming to block Wnt/β-catenin signaling, which may additionally require myeloid cell modulation to restore immunotherapy efficacy. Citation Format: Alexandra Cabanov, Ruxandra Tonea, Jason Shapiro, Anna Martinez, Yuanyuan Zha, Thomas F. Gajewski. Genetic elimination of β-catenin using a doxycycline-regulated GEM model fails to restore checkpoint blockade efficacy due to persistent M2-like macrophages [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 164.

In Vivo Study on Doxycycline Protective Mechanisms during Myocardial Ischemia Injury in Rats.

The fact that during myocardial ischemia/reperfusion (I/R) injury, myosin light chain 1 (MLC1) and troponin I (TnI) are degraded by matrix metalloproteases activity has already been well established in both in vitro and ex vivo studies. However, I/R injury is a complex issue based on several overlapping mechanisms. Increased activity of myosin light chain kinase and nitric oxide synthase due to oxidative stress leads to post-translational modifications of MLC1, thus leading to the increased degradation of these proteins. Wistar rats were subjected to left anterior descending coronary artery occlusion. To measure the pharmacological effect of doxycycline, transthoracic echocardiography as well as biochemical tests, concentrations of TnI, LDH, MLC1, MMP-2 and MMP-9 were performed. Gelatinize activity and cytotoxicity level were also assessed; Results: I.p., administration of doxycycline before LAD occlusion surgery increased TnI and LDH content in the heart and decreased cytotoxicity. A reduction of MMP-2 and MMP-9 concentration and MMP-2 activity after administration of Doxy was also observed, as well as improvement in echocardiographic parameters just 7 days after surgery. Inhibition of MMPs by doxycycline, in vivo, may serve as a protective agent in future therapy.

A Case of Chlamydophila psittaci Caused Pneumonia and Encephalitis Diagnosed by Metagenome Next-Generation Sequencing and Clinical Analysis

Introduction: Psittacosis represents a systemic infectious ailment primarily characterized by respiratory manifestations; however, the clinical presentation exhibits considerable diversity, posing challenges in promptly identifying this disease with its nonspecific features. Metagenomic next-generation sequencing (mNGS) serves as a valuable tool enabling expeditious pathogen identification and facilitating targeted therapeutic interventions. Case Presentation: An instance pertinent to this context involves a septuagenarian female patient who sought admission to Zhejiang Hospital on account of presenting with elevated body temperature, respiratory distress, and signs of altered mental state. Despite the initiation of empiric antibiotic therapy as the primary medical intervention, the patient's condition displayed a progressive deterioration. Notably, a subsequent investigation endeavor employing mNGS identified the presence of the Chlamydophila psittaci nucleic acid sequence, causative of psittacosis, within both her bloodstream and cerebrospinal fluid (CSF). The subsequent therapeutic administration of doxycycline not only elicited a marked amelioration in her clinical status but also facilitated her eventual discharge from our care. Conclusions: The coexistence of psittacosis lung infection and cerebral vasculitis is rare. Thorough documentation and analysis of such cases are essential for enhanced understanding and clinical consideration. In such cases where the infection is severe but does not respond to empirical antimicrobial therapy, mNGS can help with the diagnosis to identify the pathogen and target treatment.

Doxycycline for transgene control disrupts gut microbiome diversity without compromising acute neuroinflammatory response

The tetracycline transactivator (tTA) system provides controllable transgene expression through oral administration of the broad-spectrum antibiotic doxycycline. Antibiotic treatment for transgene control in mouse models of disease might have undesirable systemic effects resulting from changes in the gut microbiome. Here we assessed the impact of doxycycline on gut microbiome diversity in a tTA-controlled model of Alzheimer’s disease and then examined neuroimmune effects of these microbiome alterations following acute LPS challenge. We show that doxycycline decreased microbiome diversity in both transgenic and wild-type mice and that these changes persisted long after drug withdrawal. Despite the change in microbiome composition, doxycycline treatment had minimal effect on basal transcriptional signatures of inflammation the brain or on the neuroimmune response to LPS challenge. Our findings suggest that central neuroimmune responses may be less affected by doxycycline at doses needed for transgene control than by antibiotic cocktails at doses used for experimental microbiome disruption.

Overexpression of Motopsin, an Extracellular Serine Protease Related to Intellectual Disability, Promotes Adult Neurogenesis and Neuronal Responsiveness in the Dentate Gyrus.

Motopsin, a serine protease encoded by PRSS12, is secreted by neuronal cells into the synaptic clefts in an activity-dependent manner, where it induces synaptogenesis by modulating Na+/K+-ATPase activity. In humans, motopsin deficiency leads to severe intellectual disability and, in mice, it disturbs spatial memory and social behavior. In this study, we investigated mice that overexpressed motopsin in the forebrain using the Tet-Off system (DTG-OE mice). The elevated agrin cleavage or the reduced Na+/K+-ATPase activity was not detected. However, motopsin overexpression led to a reduction in spine density in hippocampal CA1 basal dendrites. While motopsin overexpression decreased the ratio of mature mushroom spines in the DG, it increased the ratio of immature thin spines in CA1 apical dendrites. Female DTG-OE mice showed elevated locomotor activity in their home cages. DTG-OE mice showed aberrant behaviors, such as delayed latency to the target hole in the Barnes maze test and prolonged duration of sniffing objects in the novel object recognition test (NOR), although they retained memory comparable to that of TRE-motopsin littermates, which normally express motopsin. After NOR, c-Fos-positive cells increased in the dentate gyrus (DG) of DTG-OE mice compared with that of DTG-SO littermates, in which motopsin overexpression was suppressed by the administration of doxycycline, and TRE-motopsin littermates. Notably, the numbers of doublecortin- and 5-bromo-2'-deoxyuridine-labeled cells significantly increased in the DG of DTG-OE mice, suggesting increased adult neurogenesis. Importantly, our results revealed a new function in addition to modulating neuronal responsiveness and spine morphology in the DG: the regulation of neurogenesis.