Leptospira-specific immunoglobulin Y (IgY) is protective in infected hamsters

Leptospirosis, a globally significant zoonotic disease caused by pathogenic Leptospira, continues to threaten the health and public safety of both humans and animals. Current clinical treatment of leptospirosis mainly relies on antibiotics but their efficacy in severe cases is controversial. Passive immunization has a protective effect in the treatment of infectious diseases. In addition, chicken egg yolk antibody (IgY) has gained increasing attention as a safe passive immunization agent. This study aimed to investigate whether hens produce specific IgY after immunization with inactivated Leptospira and the protective effect of specific IgY against leptospirosis. First, it was demonstrated that specific IgY could be extracted from the eggs of hens vaccinated with inactivated Leptospira and that specific IgY can specifically recognize and bind homotypic Leptospira with a high titre, as shown by MAT and ELISA. Next, we tested the therapeutic effects of IgY in early and late leptospirosis using a hamster model. The results showed that early specific IgY treatment increased the survival rate of hamsters to 100%, alleviated pathological damage to the liver, kidney, and lung, reduced leptospiral burden, and restored haematological indices as well as functional indicators of the liver and kidney. The therapeutic effect of early specific IgY was comparable to that of doxycycline. Late IgY treatment also enhanced the survival rate of hamsters and improved the symptoms of leptospirosis similar to early IgY treatment. However, the therapeutic effect of late IgY treatment was better when combined with doxycycline. Furthermore, no Leptospira colonization was observed in the kidneys, livers, or lungs of the surviving hamsters treated with specific IgY. Mechanistically, IgY was found to inhibit the growth and adhesion to cells of Leptospira. In conclusion, passive immunotherapy with specific IgY can be considered an effective treatment for leptospirosis, and may replace antibiotics regarding its therapeutic effects.

The impact of doxycycline on human contextual fear memory

RATIONALE

 Previous work identified an attenuating effect of the matrix metalloproteinase (MMP) inhibitor doxycycline on fear memory consolidation. This may present a new mechanistic approach for the prevention of trauma-related disorders. However, so far, this has only been unambiguously demonstrated in a cued delay fear conditioning paradigm, in which a simple geometric cue predicted a temporally overlapping aversive outcome. This form of learning is mainly amygdala dependent. Psychological trauma often involves the encoding of contextual cues, which putatively necessitates partly different neural circuits including the hippocampus. The role of MMP signalling in the underlying neural pathways in humans is unknown.

METHODS

Here, we investigated the effect of doxycycline on configural fear conditioning in a double-blind placebo-controlled randomised trial with 100 (50 females) healthy human participants.

RESULTS

Our results show that participants successfully learned and retained, after 1 week, the context-shock association in both groups. We find no group difference in fear memory retention in either of our pre-registered outcome measures, startle eye-blink responses and pupil dilation. Contrary to expectations, we identified elevated fear-potentiated startle in the doxycycline group early in the recall test, compared to the placebo group.

CONCLUSION

Our results suggest that doxycycline does not substantially attenuate contextual fear memory. This might limit its potential for clinical application.

Epsilon-poly-l-lysine microneedle patch loaded with amorphous doxycycline nanoparticles for synergistic treatment of skin infection

The development of antibiotic-loaded microneedles has been hindered for years by limited excipient options, restricted drug-loading space, poor microneedle formability, and short-term drug retention. Therefore, this study proposes a dissolving microneedle fabricated from the host-defense peptide ε-poly-l-lysine (EPL) as an antibacterial adjuvant system for delivering antibiotics. EPL serves not only as a major matrix material for the microneedle tips, but also as a broad-spectrum antibacterial agent that facilitates the intracellular accumulation of the antibiotic doxycycline (DOX) by increasing bacterial cell membrane permeability. Furthermore, the formation of physically crosslinked networks of EPL affords microneedle tips with improved formability, good mechanical properties, and amorphous nanoparticles (approximately 7.2 nm) of encapsulated DOX. As a result, a high total loading content of both antimicrobials up to 2319.1 μg/patch is achieved for efficient transdermal drug delivery. In a Pseudomonas aeruginosa-induced deep cutaneous infection model, the EPL microneedles demonstrates potent and long-term effects by synergistically enhancing antibiotic activities and prolonging drug retention in infected lesions, resulting in remarkable therapeutic efficacy with 99.91 % (3.04 log) reduction in skin bacterial burden after a single administration. Overall, our study highlights the distinct advantages of EPL microneedles and their potential in clinical antibacterial practice when loaded with amorphous DOX nanoparticles.

Doxycycline post-exposure prophylaxis could theoretically select for resistance to various antimicrobials in 19 pathobionts: an in silico analysis

OBJECTIVES

Doxycycline post exposure prophylaxis (PEP) has been shown to reduce the incidence of bacterial STIs. However, if there is genetic linkage between resistance to tetracycline and other antimicrobials, then it could also select for resistance to these other antimicrobials. We therefore undertook to evaluate if there is an association between the minimum inhibitory concentrations (MICs) of tetracycline and other antimicrobials in 19 clinically important bacterial species.

METHODS

Mixed-effects linear regression was used to assess if minocycline MICs were associated with the MICs of eight other antimicrobials (ceftriaxone, ampicillin, oxacillin, vancomycin, erythromycin, levofloxacin, amikacin, and trimethoprim-sulfamethoxazole) in 19 bacterial species in the Antimicrobial Testing Leadership and Surveillance (ATLAS) database.

RESULTS

With the notable exception of vancomycin, where no association was found, strong positive associations were typically found between the MICs of minocycline and each of the eight antimicrobials in each of the species assessed. For example, the minocycline MICs of all the Gram-positive species were positively associated with ampicillin, ceftriaxone, oxacillin and erythromycin MICs (all P-values < 0.001). The only exceptions were ampicillin for Streptococcus pyogenes and ceftriaxone for S. dysgalactiae, where no significant associations were found. Similarly in the Gram-negative species, the minocycline MICs of all the species except Haemophilus influenzae and Stenotrophomonas maltophilia were positively associated with the MICs of ceftriaxone, ampicillin, levofloxacin and amikacin (all P-values < 0.001).

CONCLUSIONS

There is a theoretical risk that doxycycline PEP could select for resistance not only to tetracyclines but to a range of other antimicrobials in each of the 19 pathobionts assessed.

Doxycycline is a viable alternative to tetracycline for use in insect Tet-Off transgenic sexing systems, as assessed in the blowflies Cochliomyia hominivorax and Lucilia cuprina (Diptera: Calliphoridae)

Transgenic insect strains with tetracycline repressible (Tet-Off) female-lethal genes provide significant advantages over traditional sterile insect techniques for insect population control, such as reduced diet and labor costs and more efficient population suppression. Tet-Off systems are suppressed by tetracycline-class antibiotics, most commonly tetracycline (Tc) or doxycycline (Dox), allowing for equal sex ratio colonies of transgenic insects when reared with Tc or Dox and male-only generations in their absence. Dox is a more stable molecule and has increased uptake than Tc, which could be advantageous in some insect mass-rearing systems. Here, we evaluated the suitability of Dox for rearing Tet-Off female-lethal strains of Australian sheep blowfly, Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae), and New World screwworm, Cochliomyia hominivorax (Coquerel, 1858) (Diptera: Calliphoridae), and the effects of dosage on strain performance. For both species, colonies were able to be maintained with mixed-sex ratios at much lower dosages of Dox than Tc. Biological yields of C. hominivorax on either antibiotic were not significantly different. Reduction of Dox dosages in C. hominivorax diet did not affect biological performance, though rearing with 10 or 25 μg/mL was more productive than 50 μg/mL. Additionally, C. hominivorax mating performance and longevity were equal on all Dox dosages. Overall, Dox was a suitable antibiotic for mass-rearing Tet-Off female-lethal L. cuprina and C. hominivorax and was functional at much lower dosages than Tc.

Antimicrobial susceptibilities of Campylobacter fetus: report from a reference laboratory

Campylobacter fetus is known to cause human disease, particularly in elderly and immunocompromised hosts. There are limited published data for antimicrobial susceptibility patterns with this organism, and no interpretive criteria are available. We reviewed antimicrobial susceptibilities of C. fetus isolates tested at a tertiary care center and reference laboratory over an 11-year period. C. fetus isolates from patients treated at Mayo Clinic and those sent as referrals for identification and susceptibility were included. Antimicrobial susceptibility testing was performed using agar dilution for ciprofloxacin, doxycycline, erythromycin, gentamicin, meropenem, and tetracycline. Geographic distribution, culture source, organism minimal inhibitory concentration (MIC) distributions, and MIC50 and MIC90 were examined. Excluding duplicates, 105 unique isolates were identified from 110 positive cultures. Blood cultures represented the most common source, followed by body fluids, skin and soft tissue, and central nervous system. Gentamicin and meropenem had favorable MIC50 and MIC90 of 1 µg/mL. Ciprofloxacin demonstrated an MIC50 of 1 µg/mL; however, the MIC90 was >2 µg/mL. Erythromycin demonstrated MIC50 and MIC90 of 2 µg/mL. Tetracycline and doxycycline were tested on a limited number of isolates and showed a wide range of MICs. Gentamicin and meropenem demonstrated favorable MICs in C. fetus isolates. These may represent therapeutic options for consideration in serious C. fetus infections, pending susceptibility results. Ciprofloxacin, which showed variable results, may be more appropriate for use only after susceptibility testing. C. fetus interpretive criteria are needed to aid clinicians in selection of both empiric and definitive therapies.

IMPORTANCE

Our findings contribute to the scant literature on Campylobacter fetus antimicrobial susceptibility test results. We used a reference test method of agar dilution and provide MICs for a large number of organisms and antimicrobial agents.

Novel Ti surface coated with PVA hydrogel and chitosan nanoparticles with antibacterial drug release: An experimental in vitro study

OBJECTIVES

The aims of this study were to design a novel titanium surface coated with a PVA hydrogel matrix and chitosan-based nanoparticles and to investigate the antibiotic release and its ability to inhibit microbial activity.

METHODS

Two drug delivery systems were developed and mixed. Chitosan-based nanoparticles (NP) and a polyvinyl alcohol film (PVA). The size, ζ-potential, stability, adhesive properties, and encapsulation profile of NP, as well as the release kinetics of drug delivery systems and their antimicrobial ability of PVA and PVANP films, were studied on Ti surfaces. The systems were loaded with doxycycline, vancomycin, and doxepin hydrochloride.

RESULTS

Nanoparticles presented a ζ-potential greater than 30 mV for 45 days and the efficiency drug encapsulation was 26.88% ± 1.51% for doxycycline, 16.09% ± 10.24% for vancomycin and 17.57% ± 11.08% for doxepin. In addition, PVA films were loaded with 125 μg/mL of doxycycline, 125 μg/mL of vancomycin, and 100 μg/mL of doxepin. PVANP-doxycycline achieved the antibacterial effect at 4 h while PVA-doxycycline maintained its effect at 24 h.

Myoglobin improves doxycycline sensitivity in pancreatic cancer through promoting heme oxygenase-1-mediated ferroptosis

Ferroptosis is expected to be a therapeutic target for cancers including pancreatic cancer. We aimed to screen genes that regulate ferroptosis and doxycycline resistance in pancreatic cancer and to explore the underlying mechanisms. Bioinformatics analysis was performed to identify genes that respond to ferroptosis in two human pancreatic cancer cells with GOT1 knocked down or not. 325 and 842 genes were upregulated in MiaPaCa and Tu8902 cells in response to GOT1 knockdown, with 43 genes shared. Among the 43 genes, 14 genes were identified to interact with ferroptosis key genes. MB and HMOX1 were the genes most sensitive to Erastin and doxycycline. Moreover, MB and HMOX1 expression was higher in human normal pancreatic duct epithelial cells than in pancreatic cancer cells. MB and HMOX1 proteins physically bound and promoted each other's expression. By interacting with HMOX1, MB suppressed pancreatic cancer cell proliferation, colony formation and invasion, and promoted cell ferroptosis and sensitivity to erastin and doxycycline. Silencing HMOX1 reversed the promoting effect of MB on cell ferroptosis and sensitivity to doxycycline. A pancreatic cancer xenograft model was established by subcutaneous injection of Panc-1 cells transfected with or without Ad-MB, and doxycycline was administered intraperitoneally. Overexpression of MB enhanced the inhibitory effect of doxycycline on xenograft growth. In conclusion, MB facilitated doxycycline sensitivity in pancreatic cancer cells through promoting HMOX1-mediated ferroptosis.

Modulating the antibacterial effect of the existing antibiotics along with repurposing drug metformin

Owing to the extensive prevalence of resistant bacteria to numerous antibiotic classes, antimicrobial resistance (AMR) poses a well-known hazard to world health. As an alternate approach in the field of antimicrobial drug discovery, repurposing the available medications which are also called antibiotic resistance breakers has been pursued for the treatment of infections with antimicrobial resistance pathogens. In this study, we used Haloperidol, Metformin and Hydroxychloroquine as repurposing drugs in in vitro (Antibacterial Antibiotic Sensitivity Test and Minimum Inhibitory Concentration-MIC) and in vivo (Shigellosis in Swiss albino mice) tests in combination with traditional antibiotics (Oxytetracycline, Erythromycin, Doxycycline, Gentamicin, Ampicillin, Chloramphenicol, and Penicillin) against a group of AMR resistance bacteria (Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Shigella boydii). After observing the results of the conducted in vitro experiments we studied the effects of the above non antibiotic drugs in combination with the said antibiotics. As an repurposing adjuvant antibiotic drug, Metformin exhibited noteworthy activity in almost all in vitro, in vivo and in silico tests (Zone of inhibition for 30 to 43 mm for E.coli in combination with Doxycycline; MIC value decreased 50 µM to 0.781 µM with Doxycycline on S. boydii).In rodents Doxycycline and Metformin showed prominent against Shigellosis in White blood cell count (6.47 ± 0.152 thousand/mm3) and Erythrocyte sedimentation rate (10.5 ± 1.73 mm/hr). Our findings indicated that Metformin and Doxycycline combination has a crucial impact on Shigellosis. The molecular docking study was performed targeting the Acriflavine resistance protein B (AcrB) (PDB ID: 4CDI) and MexA protein (PDB ID: 6IOK) protein with Metformin (met8) drug which showed the highest binding energy with - 6.4 kcal/mol and - 5.5 kcal/mol respectively. Further, molecular dynamics simulation revealed that the docked complexes were relatively stable during the 100 ns simulation period. This study suggest Metformin and other experimented drugs can be used as adjuvants boost up antibiosis but further study is needed to find out the safety and efficacy of this non-antibiotic drug as potent antibiotic adjuvant.

Generation of a gene-edited H9 embryonic stem cell line carrying a DOX-inducible NGN2 expression cassette in the CLYBL locus

The pro-neural transcription factor neurogenin-2 (NGN2) possesses the ability to rapidly and effectively transform stem cells into fully operational neurons. Here we report the successful generation of a modified H9 human embryonic H9 stem cell line containing a doxycycline (DOX) inducible NGN2 expression construct featuring a floxed Blasticidin/mApple selection module in the safe-harbor locus CLYBL. This cell line retains its pluripotent state in the absence of DOX, yet readily transitions into a neuronal state upon DOX introduction.

The antidepressant-like effect of doxycycline is associated with decreased nitric oxide metabolite levels in the prefrontal cortex

Doxycycline is an antibiotic that has shown neuroprotective, anti-inflammatory, and antidepressant-like effects. Low doses of doxycycline revert the behavioral and neuroinflammatory responses induced by lipopolysaccharide treatment in a mice model of depression. However, the molecular mechanisms involved in the antidepressant action of doxycycline are not yet understood. Doxycycline inhibits the synthesis of nitric oxide (NO), which increases after stress exposure. Inducible NO synthase (iNOS) inhibition also causes antidepressant-like effects in animal models sensitive to antidepressant-like effects such as the forced swimming test (FST). However, no direct study has yet investigated if the antidepressant-like effects of doxycycline could involve changes in NO-mediated neurotransmission. Therefore, this study aimed at investigating: i) the behavioral effects induced by doxycycline alone or in association with ineffective doses of a NO donor (sodium nitroprusside, SNP) or an iNOS inhibitor (1400 W) in mice subjected to the FST; and ii) doxycycline effects in NO metabolite levels in the prefrontal cortex and hippocampus these animals. Male mice (8 weeks) received i.p. injection of saline or doxycycline (10, 30, and 50 mg/kg), alone or combined with SNP (0.1, 0.5, and 1 mg/kg) or 1400 W (1, 3, and 10 µg/kg), and 30 min later were submitted to the FST. Animals were sacrificed immediately after, and NO metabolites nitrate/nitrite (NOx) were measured in the prefrontal cortex and hippocampus. Doxycycline (50 mg/kg) reduced both the immobility time in the FST and NOx levels in the prefrontal cortex of mice compared to the saline group. The antidepressant-like effect of doxycycline in the FST was prevented by SNP (1 mg/kg) pretreatment. Additionally, sub-effective doses of doxycycline (30 mg/kg) associated with 1400 W (1 µg/kg) induced an antidepressant-like effect in the FST. Altogether, our data suggest that the reducing NO levels in the prefrontal cortex through inhibition of iNOS could be related to acute doxycycline treatment resulting in rapid antidepressant-like effects in mice.

Quantitative MRI Evaluation of Ferritin Overexpression in Non-Small-Cell Lung Cancer

Cancer cells frequently present elevated intracellular iron levels, which are thought to facilitate an enhanced proliferative capacity. Targeting iron metabolism within cancer cells presents an avenue to enhance therapeutic responses, necessitating the use of non-invasive models to modulate iron manipulation to predict responses. Moreover, the ubiquitous nature of iron necessitates the development of unique, non-invasive markers of metabolic disruptions to develop more personalized approaches and enhance the clinical utility of these approaches. Ferritin, an iron storage enzyme that is often upregulated as a response to iron accumulation, plays a central role in iron metabolism and has been frequently associated with unfavorable clinical outcomes in cancer. Herein, we demonstrate the successful utility, validation, and functionality of a doxycycline-inducible ferritin heavy chain (FtH) overexpression model in H1299T non-small-cell lung cancer (NSCLC) cells. Treatment with doxycycline increased the protein expression of FtH with a corresponding decrease in labile iron in vitro and in vivo, as determined by calcein-AM staining and EPR, respectively. Moreover, a subsequent increase in TfR expression was observed. Furthermore, T2* MR mapping effectively detected FtH expression in our in vivo model. These results demonstrate that T2* relaxation times can be used to monitor changes in FtH expression in tumors with bidirectional correlations depending on the model system. Overall, this study describes the development of an FtH overexpression NSCLC model and its correlation with T2* mapping for potential use in patients to interrogate iron metabolic alterations and predict clinical outcomes.

Establishment of African pygmy mouse induced pluripotent stem cells using defined doxycycline inducible transcription factors

Mus minutoides is one of the smallest mammals worldwide; however, the regulatory mechanisms underlying its dwarfism have not been examined. Therefore, we aimed to establish M. minutoides induced pluripotent stem cells (iPSCs) using the PiggyBac transposon system for applications in developmental engineering. The established M. minutoides iPSCs were found to express pluripotency markers and could differentiate into neurons. Based on in vitro differentiation analysis, M. minutoides iPSCs formed embryoid bodies expressing marker genes in all three germ layers. Moreover, according to the in vivo analysis, these cells contributed to the formation of teratoma and development of chimeric mice with Mus musculus. Overall, the M. minutoides iPSCs generated in this study possess properties that are comparable to or closely resemble those of naïve pluripotent stem cells (PSCs). These findings suggest these iPSCs have potential utility in various analytical applications, including methods for blastocyst completion.

Doxycycline hydrochloride inhibits the progress of malignant rhabdoid tumor of kidney by targeting MMP17 and MMP1 through PI3K-Akt signaling pathway

OBJECTIVE

To identify therapeutic targets for malignant rhabdoid tumors of kidney (MRTK) and to investigate the effects and underlying mechanism of doxycycline hydrochloride on these tumors.

METHODS

Gene expression and clinical data of MRTK were retrieved from the TARGET database. Differentially expressed genes (DEGs) and prognostic-related genes (PRGs) were selected through a combination of statistical analyses. The functional roles of MMP17 and MMP1 were elucidated through RNA overexpression and intervention experiments. Furthermore, in vitro and in vivo studies provided evidence for the inhibitory effect of doxycycline hydrochloride on MRTK. Additionally, transcriptome sequencing was employed to investigate the underlying molecular mechanisms.

RESULTS

3507 DEGs and 690 PRGs in MRTK were identified. Among these, we focused on 41 highly expressed genes associated with poor prognosis and revealed their involvement in extracellular matrix regulatory pathways. Notably, MMP17 and MMP1 stood out as particularly influential genes. When these genes were knocked out, a significant inhibition of proliferation, invasion and migration was observed in G401 cells. Furthermore, our study explored the impact of the matrix metalloproteinase inhibitor, doxycycline hydrochloride, on the malignant progression of G401 both in vitro and in vivo. Combined with sequencing data, the results indicated that doxycycline hydrochloride effectively inhibited MRTK progression, due to its ability to suppress the expression of MMP17 and MMP1 through the PI3K-Akt signaling pathway.

CONCLUSION

Doxycycline hydrochloride inhibits the expression of MMP17 and MMP1 through the PI3K-Akt signaling pathway, thereby inhibiting the malignant progression of MRTK in vivo and in vitro.

Reprogramming a Doxycycline-Inducible Gene Switch System for Bacteria-Mediated Cancer Therapy

PURPOSE

Attenuated Salmonella typhimurium is a potential biotherapeutic antitumor agent because it can colonize tumors and inhibit their growth. The present study aimed to develop a doxycycline (Doxy)-inducible gene switch system in attenuated S. typhimurium and assess its therapeutic efficacy in various tumor-bearing mice models.

PROCEDURES

A Doxy-inducible gene switch system comprising two plasmids was engineered to trigger the expression of cargo genes (Rluc8 and clyA). Attenuated S. typhimurium carrying Rluc8 were injected intravenously into BALB/c mice bearing CT26 tumors, and bioluminescence images were captured at specified intervals post-administration of doxycycline. The tumor-suppressive effects of bacteria carrying clyA were evaluated in BALB/c mice bearing CT26 tumors and in C57BL/6 mice bearing MC38 tumors.

RESULTS

Expression of the fimE gene, induced only in the presence of Doxy, triggered a unidirectional switch of the POXB20 promoter to induce expression of the cargo genes. The switch event was maintained over a long period of bacterial culture. After intravenous injection of transformed Salmonella into mice bearing CT26 tumors, the bacteria transformed with the Doxy-inducible gene switch system for Rluc8 targeted only tumor tissues and expressed the payloads 2 days after Doxy treatment. Notably, bacteria carrying the Doxy-inducible gene switch system for clyA effectively suppressed tumor growth and prolonged survival, even after just one Doxy induction.

CONCLUSIONS

These results suggest that attenuated S. typhimurium carrying this novel gene switch system elicited significant therapeutic effects through a single induction triggering and were a potential biotherapeutic agent for tumor therapy.

Pentachlorophenol affects doxycycline and tetracycline resistance genes in soil by altering microbial structure

Tetracycline antibiotics play a vital role in animal husbandry, primarily employed to uphold the health of livestock and poultry. Consequently, when manure is reintegrated into farmland, tetracycline antibiotics can persist in the soil. Simultaneously, to ensure optimal crop production, organochlorine pesticides (OCPs) are frequently applied to farmland. The coexistence of tetracycline antibiotics and OCPs in soil may lead to an increased risk of transmission of tetracycline resistance genes (TRGs). Nevertheless, the precise mechanism underlying the effects of OCPs on tetracycline antibiotics and TRGs remains elusive. In this study, we aimed to investigate the effects of OCPs on soil tetracycline antibiotics and TRGs using different concentrations of doxycycline (DOX) and pentachlorophenol (PCP). The findings indicate that PCP and DOX mutually impede their degradation in soil. Furthermore, our investigation identifies Sphingomonas and Bacillus as potential pivotal microorganisms influencing the reciprocal inhibition of PCP and DOX. Additionally, it is observed that the concurrent presence of PCP and DOX could impede each other's degradation by elevating soil conductivity. Furthermore, we observed that a high concentration of PCP (10.7 mg/kg) reduced the content of efflux pump tetA, ribosome protective protein tetM, tetQ, and passivating enzyme tetX. In contrast, a low PCP concentration (6.4 mg/kg) only reduced the content of ribosome protective protein tetQ. This suggests that PCP may reduce the relative abundance of TRGs by altering the soil microbial community structure and inhibiting the potential host bacteria of TRGs. These findings have significant implications in understanding the combined pollution of veterinary antibiotics and OCPs. By shedding light on the interactions between these compounds and their impact on microbial communities, this study provides a theoretical basis for developing strategies to manage and mitigate their environmental impact, and may give some information regarding the sustainable use of antibiotics and pesticides to ensure the long-term health and productivity of agricultural systems.

Systemic antibiotic treatment for meibomian gland dysfunction-A systematic review and meta-analysis

PURPOSE

To review the efficacy and safety of oral doxycycline antibiotics versus macrolides in the treatment of meibomian gland dysfunction (MGD).

DESIGN

Systematic review and meta-analysis.

METHODS

We performed a systematic search of electronic databases for all peer-reviewed published studies which included clinical outcomes of oral antibiotic MGD treatment. Individual study data were extracted and evaluated in a weighted pooled analysis, including total sign and symptom scores, meibomian gland secretion score, tear break-up time (TBUT), fluorescein staining score and rate of complications.

RESULTS

Two thousand nine hundred and thirty-three studies were found, of which 54 were eligible for the systematic review, and six prospective studies were ultimately included for analysis, reporting on 563 cases from three countries. Age of affected patients ranged between 12 and 90 years. Overall, both treatment methods induced improvement in MGD signs and symptoms. In pooled analysis, macrolides were significantly superior in the total signs score (pooled standardized mean difference (SMD) -0.51, 95% confidence interval (CI): -0.99 to -0.03), meibomian gland secretion score (pooled SMD -0.25, 95%CI: [-0.48, -0.03]), TBUT (SMD -0.31, 95%CI: [-0.50, -0.13]) and fluorescein staining score (SMD -1.01, 95%CI: [-1.72, -0.29]). Moreover, while no severe complications were reported for both treatments, the macrolide group exhibited significantly less adverse events (pooled odds ratio 0.24 with a 95% CI of 0.16 to 0.34).

CONCLUSIONS

Both macrolides and tetracyclines are effective treatments for MGD. In this study, macrolides exhibited better efficacy and safety profile compared to tetracyclines.

Assessing the colony morphotypes and antibiotic susceptibility profile of Malaysian clinical Burkholderia pseudomallei to support the use of EUCAST disk diffusion breakpoints to determine antibiotic resistance

Burkholderia pseudomallei is intrinsically resistant to many antibiotics. This study aimed to assess bacterial colony morphotypes and the validity of using disk diffusion method (DD) to determine antibiotic resistance in Malaysian clinical B. pseudomallei isolates for ceftazidime (CAZ), meropenem (MEM), amoxicillin-clavulanate (AMC) and doxycycline (DOX). DD produced good categorical agreements exhibiting concordance of 100% with reference method, broth microdilution for CAZ and DOX, 98.6% for MEM and 97.2% for AMC. Smooth-centred colonies were most frequently observed. EUCAST DD interpretative criterion is suitable to interpret B. pseudomallei CAZ, MEM, AMC and DOX resistance. Increasing AMC MIC in B. pseudomallei is a concern.

Utilizing the photodynamic properties of curcumin to disrupt biofilms in Cutibacterium acnes: A promising approach for treating acne

BACKGROUND

The treatment of acne vulgaris is often challenging due to the antibiotic resistance frequently observed in Cutibacterium acnes (C.acnes), a prevalent bacterium linked to this condition.

OBJECTIVE

The objective of this research was to examine the impact of curcumin photodynamic therapy (PDT) on the survival of C.acnes and activity of biofilms produced by this microorganism.

METHODS

Following the Clinical and Laboratory Standards Institute (CLSI) guidelines, we assessed the drug sensitivity of 25 clinical C.acnes strains to five antibiotics (erythromycin, clindamycin, tetracycline, doxycycline, minocycline) and curcumin by implementing the broth microdilution technique. In addition, we established C.acnes biofilms in a laboratory setting and subjected them to curcumin-PDT(curcumin combined with blue light of 180 J/cm2). Afterwards, we evaluated their viability using the XTT assay and observed them using confocal laser scanning microscopy.

RESULTS

The result revealed varying resistance rates among the tested antibiotics and curcumin, with erythromycin, clindamycin, tetracycline, doxycycline, minocycline, and curcumin exhibiting resistance rates of 72 %, 44 %, 36 %, 28 %, 0 %, and 100 %, respectively. In the curcumin-PDT inhibition tests against four representative antibiotic-resistant strains, it was found that the survival rate of all strains of planktonic C. acnes was reduced, and the higher the concentration of curcumin, the lower the survival rate. Furthermore, in the biofilm inhibition tests, the vitality and three-dimensional structure of the biofilms were disrupted, and the inhibitory effect became more significant with higher concentrations of curcumin.

CONCLUSION

The results emphasize the possibility of using curcumin PDT as an alternative approach for the treatment of C.acnes, especially in instances of antibiotic-resistant variations and infections related to biofilms.

Antimicrobial Susceptibility of Francisella tularensis Isolates in the United States, 2009-2018

Francisella tularensis is the causative agent of tularemia. We tested the susceptibility of 278 F. tularensis isolates from the United States received during 2009-2018 to 8 antimicrobial drugs (ciprofloxacin, levofloxacin, doxycycline, tetracycline, gentamicin, streptomycin, chloramphenicol, and erythromycin). All isolates were susceptible to all tested drugs.

Matrix metalloproteinases inhibition reveals the association between inflammation, collagen accumulation and intestinal translocation of Schistosoma mansoni eggs in vivo

Schistosomiasis mansoni is a parasitic infection that causes enterohepatic morbidity associated with severe granulomatous inflammation triggered by parasite eggs. In this disease, granulomatous inflammation leads to intestinal erosion and environmental excretion of S. mansoni eggs from feces, an essential process for propagating the parasite and infecting host organisms. Metalloproteinases (MMP) are involved in S. mansoni-induced hepatic granulomatous inflammation and fibrosis. However, the relationship between MMP and collagen accumulation with the intestinal excretion of parasite eggs remains unclear. Thus, the present study investigated whether MMP inhibition is capable of modulating granulomatous inflammation, collagen accumulation and mechanical resistance to the point of influencing the dynamics between intestinal retention and excretion of S. mansoni eggs in infected mice. Our findings indicated that doxycycline (a potent MMP inhibitor) aggravates intestinal inflammation and subverts collagen dynamics in schistosomiasis. By attenuating MMP-2 and MMP-9 activity, this drug is capable of enhancing fibrosis and mechanical resistance of the intestinal wall, hindering S. mansoni eggs translocation. Although collagen content was not correlated with MMP activity, intestinal retention and fecal excretion of parasite eggs in untreated mice; these correlations were observed for doxycycline-treated animals. Thus, our study provides evidence that doxycycline is able to attenuate fecal elimination of S. mansoni eggs by inhibiting MMP-2 and MMP-9 activity, events potentially associated with excessive collagen accumulation, which increases intestinal mechanical resistance and hinders eggs translocation through the intestinal wall. Variations in intestinal collagen dynamics are relevant since they may represent changes in the environmental dispersion of S. mansoni eggs, bringing repercussions for schistosomiasis propagation.

Doxycycline diminishes the rewarding and psychomotor effects induced by morphine and cocaine

Few pharmacological treatments are available for substance use disorders (SUDs). Neuroplastic changes induced by increased activity of metalloproteinase (MMP) enzymes in the brain are among the several molecular processes that may play a role in drug addiction. Doxycycline, a widely used tetracycline that crosses the blood-brain barrier, inhibits MMPs and has been investigated as a potential treatment for brain disorders. However, the effects of doxycycline on rewarding properties of drugs of abuse remain not investigated. Here, we tested the effects of low doses of doxycycline on the rewarding effects of morphine and cocaine in conditioned place preference (CPP) and locomotor sensitization in mice. Acute doxycycline (10 mg/kg) attenuated the cocaine-induced CPP and hyperlocomotion. Repeated doxycycline (10 mg/kg) blocked hyperlocomotion and attenuated the locomotor sensitization induced by cocaine. It also decreased the rewarding effects in the CPP induced by morphine and cocaine. Our results suggest that doxycycline could be repurposed for treating SUDs.

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.

Combination of Doxycycline with Metronidazole Protects against Pyroptosis in Rats with Endometritis through the Modulation of TLR4/NF-κB Pathway

BACKGROUND

Endometritis is a condition usually resulted from the bacterial infection of uterus, causing pelvic disease, sepsis, shock, uterine necrosis and even death if it is inappropriately treated. The aim of this study is to explore the pathogenesis of endometritis, and investigate whether the combination of doxycycline and metronidazole offers stronger protection against lipopolysaccharide (LPS)-induced endometritis, and decipher more about the mechanisms underlying endometritis-related pyroptosis.

METHODS

Sprague-Dawley (SD) rats were divided into five groups (n = 8 per group): control, model, metronidazole, doxycycline, and combination groups. In control group, the rats were injected with saline, while in other groups, lipopolysaccharide was injected into uterus of the rats to establish endometritis. Hematoxylin-eosin (H&E) staining was performed as part of the histopathological examination of endometrium. The integrity of chromatin and pyroptosis were evaluated by terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay. Western blot and quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) were performed to ascertain the activation of toll-like receptors (TLR4)/nuclear factor-kappa B (NF-κB) pathway by detecting protein levels of phosphorylated p50 (p-p50)/p50, phosphorylated nuclear factor-kappa B (p-NF-κB)/NF-κB, phosphorylated IkappaB (p-IκB), and TLR4 protein and mRNA. Development of pyroptosis was also detected by determining the levels of caspase-1 and caspase-5 through Western blot and qRT-PCR. Enzyme-linked immunosorbent assay (ELISA) was used to detect levels of interleukin (IL)-1β, IL-18, IL-2, IL-4, IL-6 and tumor necrosis factor alpha (TNF-α), and flow cytometry was adopted to determine T-helper (Th)1 and Th2 cell percentage to assess the extent of pyroptosis and Th1/Th2 imbalance.

RESULTS

The uterine of the model group exhibited pathological alterations and higher degree of cell apoptosis. Compared with the control rats, model group showed lower protein levels of p-p50/p50 (p < 0.001), p-NF-κB/NF-κB (p < 0.001), p-IκB (p < 0.001), and TLR4 protein (p < 0.001) and mRNA (p < 0.001). Elevated levels of caspase-1 (p < 0.001), caspase-5 (p < 0.001), IL-1β (p < 0.001), IL-18 (p < 0.001), IL-2 (p < 0.01), TNF-α (p < 0.05) and Th1/Th2 (p < 0.001) as well as reduced levels of IL-4 (p < 0.05) and IL-6 (p < 0.01) were observed in the model group, which could however be reversed by metronidazole (p < 0.01) or doxycycline (p < 0.01), with a more significant effect detected if a combination of the two drugs was administered (p < 0.01).

CONCLUSIONS

The combination of doxycycline and metronidazole protects against rat endometritis by inhibiting TLR4/NF-κB pathway-mediated inflammation and suppressing pyroptosis.

A multicenter retrospective electronic health record database evaluation of subjects with Mycoplasma genitalium

BACKGROUND

Mycoplasma genitalium is a sexually transmitted infection (STI) increasing in prevalence. The recent availability of nucleic acid amplification tests (NAATs) has led to updated diagnostic and treatment guidelines. As medication therapy experts, pharmacists can facilitate appropriate antimicrobial selection and stewardship and optimize best patient-care practices in the setting of M. genitalium infection.

OBJECTIVE

This study aimed to evaluate patient demographics, therapeutic approaches, and complications of patients with laboratory evidence of M. genitalium hypothesizing that younger adolescent females are affected by this organism, receive suboptimal treatment, and have more complications than adults.

METHODS

This was a retrospective cohort study using TriNetX multicenter electronic health record data of subjects aged 12 years and older with evidence of M. genitalium DNA detected via NAATs. The cohort was divided into 2 age groups: adolescents (12-21 years) and adults (older than 21 years). We evaluated age, sex, race, ethnicity, diagnostic codes, and medication codes.

RESULTS

Our study included 1126 subjects (192 adolescents [17.1%] and 934 adults [82.9%]) who tested positive for M. genitalium. Subjects in the adolescent group had higher odds of being women (2.52 [1.80, 3.54], P < 0.001), having inflammatory diseases of female pelvic organs diagnostic codes (1.51 [1.06, 2.16], P = 0.025), increased odds of azithromycin prescription (1.70 [1.17, 2.48], P = 0.005), and decreased odds of moxifloxacin prescription (0.41 [0.26, 0.64], P < 0.001).

CONCLUSIONS

Our study revealed a higher prevalence of M. genitalium infection in adults and adolescents with increased odds of receiving azithromycin and decreased odds of receiving moxifloxacin. Both age groups had decreased odds of receiving doxycycline compared with azithromycin despite guidelines recommending initial empirical antibiotic treatment with doxycycline and growing macrolide resistance. Suboptimal treatment of this infection may lead to lifelong complications. Pharmacists may provide crucial guidance and education to both patients and health care providers regarding appropriate treatment for M. genitalium.

The effect of doxycycline on canine neutrophil functions

Doxycycline is a broad-spectrum tetracycline-class antibiotic that is frequently used to treat bacterial infections. Its use has also been described in immune-mediated diseases due to its immunomodulatory properties. The aim of this study was to evaluate the immunomodulatory effect of doxycycline on canine neutrophil functions. Therefore, the release of reactive oxygen species (ROS) and the formation of neutrophil extracellular traps (NETs) were determined after incubation of canine PMNs with doxycycline in three different concentrations (4 µg/mL, 20 µg/mL and 200 µg/mL) for one and three hours, respectively. Additionally, a neutrophil killing assay with a doxycycline-resistant Staphylococcus aureus was performed to determine the bactericidal effect of doxycycline treated PMNs in presence of plasma. Doxycycline significantly diminished the production of ROS. However, doxycycline concentrations of 4 µg/mL and 20 µg/mL significantly induced NETs. A synergistic bacteriostatic effect of PMNs and doxycycline on a doxycycline-resistant Staphylococcus aureus isolate was detectable. However, already PMNs and especially doxycycline alone inhibited the growth. In summary, doxycycline showed a concentration-dependent immunomodulatory property in canine PMNs with a reduced ROS production and increased NET-induction. This immunomodulatory effect resulted in a slightly increased elimination of a doxycycline-resistant Staphylococcus aureus by the doxycycline plasma concentrations achieved in dogs.

A polyglutamic acid/tannic acid-based nano drug delivery system: Antibacterial, immunoregulation and sustained therapeutic strategies for oral ulcers

Oral ulcers are a common inflammatory mucosal ulcer, and the moist and dynamic environment in the oral cavity makes topical pharmacological treatment of oral ulcers challenging. Herein, oral ulcer tissue adhesion nanoparticles were prepared by using esterification reaction between polyglutamic acid and tannic acid, and at the same time doxycycline hydrochloride was loaded into the nanoparticles. The obtained slow drug release effect of the drug-loaded nanoparticles reduced the toxicity of the drug, and by penetrating into the fine crevice region of the wound tissue and adhering to it, they could in-situ release the carried drug more effectively and thus have shown significant antibacterial effects. In addition, tannic acid in the system conferred adhesion, antioxidant and immune regulation activities to the nanocarriers. A rat oral ulcer model based on fluorescent labeling was established to investigate the retention of nanoparticles at the ulcer, and the results showed that the retention rate of drug-loaded nanoparticles at the ulcer was 17 times higher than that of pure drug. Due to the antibacterial and immune regulation effects of the drug-loaded nanoparticles, the healing of oral ulcer wounds was greatly accelerated. Such application of doxycycline hydrochloride loaded polyglutamic acid/tannic acid nanoparticles is a novel and effective treatment strategy for oral ulcer.

Planktonic and biofilm states of Staphylococcus aureus isolated from bone and joint infections and the in vitro effect of orally available antibiotics

AIMS

To demonstrate the in vitro activity of orally available antibiotics against Staphylococcus aureus isolated from bone or orthopedic implant materials. The biofilm eradication of the combination of three antibiotics was also assessed.

METHODS AND RESULTS

Clinical isolates from orthopedic infection samples were collected, and S. aureus isolates were classified according to their biofilm production and composition. Almost all S. aureus isolates (n = 36, 97.3%) produced biofilm and the major biofilm components were polysaccharides. Antimicrobial susceptibility was determined in planktonic (minimal inhibitory concentration; MIC) and biofilm cells (minimal biofilm eradication concentration; MBEC) using the MBEC Calgary Device. Overall, the MBEC ranged higher than the MIC. When combined at borderline-susceptible concentrations, moxifloxacin-rifampin and doxycycline-rifampin were both able to eradicate biofilms in a third of the strains whereas the doxycycline-moxifloxacin combination proved ineffective at eradicating biofilm, inhibiting it only in three strains.

CONCLUSIONS

We propose rifampin in combination with moxifloxacin or doxycycline for the design of clinical trials of bone and/or orthopedic device infection without proper debridement or material retention.

An oral caspase inhibitor as monotherapy or with antibiotics eradicates MRSA skin infections in mice

Staphylococcus aureus is the leading cause of skin and soft tissue infections. With the emergence of antibiotic-resistant bacteria, there is an unmet clinical need to develop immune-based therapies to treat skin infections. Previously, we have shown pan-caspase inhibition as a potential host-directed immunotherapy against community-acquired methicillin-resistant S aureus (CA-MRSA) and other bacterial skin infections. Here, we evaluated the role of irreversible pan-caspase inhibitor emricasan as a monotherapy and an adjunctive with a standard-of-care antibiotic, doxycycline, as potential host-directed immunotherapies against S. aureus skin infections in vivo. We used the established CA-MRSA strain USA300 on the dorsum of WT C57BL/6J mice and monitored lesion size and bacterial burden noninvasively, and longitudinally over 14 days with in vivo bioluminescence imaging (BLI). Mice in four groups placebo (0.5% carboxymethyl cellulose [CMC] solution), placebo plus doxycycline (100 mg/kg), emricasan (40 mg/kg) plus doxycycline, and emricasan only were treated orally twice daily by oral gavage for 7 days, starting at 4 h after injection of S aureus. When compared with placebo, all three groups, placebo plus doxycycline, emricasan plus doxycycline, and emricasan treated group, exhibited biological effect, with reduction of both the lesion size (*p = .0277, ****p < .0001, ****p < .0001, respectively) and bacterial burden (***p = .003, ****p < .0001, ****p < .0001, respectively). Importantly, the efficacy of emricasan against S. aureus was not due to direct antibacterial activity. Collectively, pan-caspase inhibitor emricasan and emricasan plus doxycycline reduced both the lesion size and bacterial burden in vivo, and emricasan is a potential host-directed immunotherapy against MRSA skin infections in a preclinical mouse model.

Development of chitosan-hyaluronic acid based hydrogel for local delivery of doxycycline hyclate in an ex vivo skin infection model

Doxycycline hyclate (DOXY) is a tetracycline derivative known as the broad-spectrum bacteriostatic drug. DOXY has been suggested as the first-line antibiotic for diabetic foot ulcers (DFU). Unfortunately, the long-term availability of DOXY in both oral and conventional topical dosage forms reduces its therapeutic effectiveness, which is closely linked to gastrointestinal side effects and acute pain during therapy, as well as uncontrolled DOXY release at the wound site. To address these shortcomings, we present for the first time a DOXY hydrogel system (DHs) built on crosslinks between carboxymethyl chitosan (CMC) and aldehyde hyaluronic acid (AHA). Three formulations of DHs were developed with different ratios of CMC and AHA, consisting of F1 (3:7, w/w), F2 (5:5, w/w), and F3 (7:3, w/w). Viscosity, rheology, gel strength, pH, swelling, gel fraction, wettability, stability, in vitro drug release, ex vivo antibacterial, and dermatokinetic studies were used to evaluate the DHs. According to the in vitro release study, up to 85% of DOXY was released from DHs via the Fickian diffusion mechanism in the Korsmeyer-Peppas model (n < 0.45), which provides controlled drug delivery. Because of its excellent physicochemical characteristics, F2 was chosen as the best DHs formulation in this study. Essentially, the optimum DHs formulation could greatly improve DOXY's ex vivo dermatokinetic profile while also providing excellent antibacterial activity. As a consequence, this study had promising outcome as a proof of concept for increasing the efficacy of DOXY in clinical therapy. Further extensive in vivo studies are required to evaluate the efficacy of this approach.

In vitro combination with doxycycline plus antifungals against clinical Mucorales pathogens

PURPOSE

Since systematic antifungals for mucormycosis showed variable MICs depending on strains, effective and safe antifungal therapy was still needed. This study is aimed to evaluate the in vitro activity of doxycycline combined with antifungal therapy against dominant Mucorales pathogens.

METHODS

Multidrug susceptibility testing was performed with doxycycline and antifungals, including itraconazole, posaconazole, and amphotericin, in 21 isolates of 8 dominant Mucorales pathogens.

RESULTS

The fractional inhibitory concentration index according to M38 showed one Rhizopus arrhizus isolate synergic (∑FICI = 0.375) and other isolates in addition (0.5 < ∑FICI < 4).

CONCLUSIONS

Doxycycline was found to have in vitro advantages in combined antifungal treatment over antifungals alone.

Synergistic effect of doxycycline and aqueous extract of irradiated khella on structure of nanobacteria isolated from kidney stones: In vitro and in vivo studies

Kidney stones have been associated with an increased risk of chronic kidney diseases, end-stage renal failure. This study is devoted to isolate nanobacteria from patients with active urolithiasis and investigate the in vitro and in vivo antinanobacterial activity of some antibiotics alone or in combination with extracts of irradiated herbs from certain medicinal plants. Nanobacteria were detected using scanning (SEM) and transmission (TEM) electron microscopy, protein electrophoresis (SDS-PAGE) and DNA profile. The antimicrobial susceptibility of some biofilm-producing nanobacterial isolates was evaluated. The effect of medicinal plant extracts on growth was tested. A combination treatment between the most potent extracts and antibiotics was tested on biofilm production, protein profile, release of 260 nm absorbing material, protein content, and ultrastructure of the strongest biofilm producers. In vivo study of nanobacteria and its treatment by the most potent agents was evaluated on male rats. Renal function was measured in serum; histological examination and oxidative stress parameters were determined in kidney tissues. Results showed that streptomycin, trimethoprim/sulfamethoxazole, doxycycline, and water extracts of irradiated khella at 6 kGy had antinanobacterial activity. Meanwhile, the synergistic effect of the aqueous extract of irradiated Khella and doxycycline showed higher inhibition activity on microbial growth and biofilm production. They affected dramatically the strength of its cell membrane and subsequently its ultrastructure. Moreover, these results are confirmed by ameliorations in renal function and histological alterations. It could be concluded that the combination of DO and an aqueous extract of irradiated khella has an antinephrotoxic effect against nanobacteria-induced renal toxicity.

Doxycycline post exposure prophylaxis could select for cross-resistance to other antimicrobials in various pathogens: An in silico analysis

BACKGROUND

A number of randomized controlled trials have found that doxycycline post exposure prophylaxis (PEP) can reduce the incidence of gonorrhoea, chlamydia and syphilis in men who have sex with men (MSM). If tetracycline resistance is associated with resistance to other antimicrobials in a range of bacterial species, then doxycycline PEP could have the unintended effect of selecting for resistance to other antimicrobials in these bacterial species.

METHODS

Antimicrobial susceptibility data were retrieved from two sources: pubMLST (https://pubmlst.org/) and Pathogenwatch (https://pathogen.watch/) for the following bacterial pathogens: Klebsiella pneumoniae, Salmonella enterica subsp. Enterica serovar Typhi, Campylobacter jejuni, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes. We assessed if tetracycline resistance was associated with resistance to six relevant antimicrobials.

RESULTS

We found evidence of cross resistance to various antimicrobials in all six bacterial species assessed. Cross resistance was found in 4 of 5 antimicrobials for K. pneumoniae, 1 of 2 for C. jejuni, 3 of 5 for S. enterica subsp. Enterica serovar Typhi, 5 of 5 for S. aureus, 5 of 6 for S. pneumoniae and 2 of 3 for S. pyogenes. These associations include a higher prevalence of methicillin resistance in tetracycline resistant S. aureus, penicillin resistance in S. pneumoniae, macrolide and clindamycin resistance in S. pyogenes, fluoroquinolone resistance in S. enterica subsp. Enterica serovar Typhi and third-generation cephalosporin resistance in K. pneumoniae.

CONCLUSION

These results suggest that studies evaluating the effects of doxycycline PEP should include the effects of doxycycline on resistance not only to doxycycline but also to other antimicrobials and in a broader array of bacterial species than has been included in doxycycline PEP studies thus far.

Physiological and biochemical responses of soft coral Sarcophyton trocheliophorum to doxycycline hydrochloride exposure

In light of the rapid expansion of the marine aquaculture industry, there has been widespread and irregular usage of aquatic drugs to combat biological diseases, which significantly impact the neighboring aquatic ecosystems. This study delves into the impact of the antibiotic aquatic drug known as doxycycline hydrochloride (DOX) on offshore soft corals, providing valuable data for the responsible use and management of aquatic drugs. In this investigation, we subjected Sarcophyton trocheliophorum to acute exposure to varying concentrations of DOX (0, 1, 5, and 10 mg L-1). We meticulously assessed critical parameters and observed alterations in protein levels, superoxide dismutase (SOD) activity, catalase (CAT) activity, lipid peroxidation (LPO), malondialdehyde (MDA) levels, Acid phosphatase (ACP) activity, alkaline phosphatase (AKP) activity, glutathione (GSH) concentration, glutathione S-transferase (GST) activity, glutathione Peroxidase (GSH-Px) activity, zooxanthellae density, and chlorophyll content. Our findings reveal that in the presence of DOX-induced environmental stress, there is a significant increase in LPO, MDA, chlorophyll, carotenoid levels, and the activities of ACP, GST, and GSH-Px in soft corals. Simultaneously, there is a noteworthy decrease in zooxanthellae density. Additionally, the protein concentration and SOD activity in soft corals experience substantial reduction when exposed to 5 mg L-1 DOX. Notably, CAT activity varies significantly in environments with 1 and 10 mg L-1 DOX. Moreover, these conditions exhibit a discernible influence on AKP activity, GSH content, and chlorophyll levels. These findings suggest that DOX exposure carries the potential for toxicity in aquaculture settings, affecting protein synthesis in soft corals and influencing oxidative stress, lipid peroxidation, immunity, and detoxification processes within these organisms. There is also a risk of compromising the coral defense system, potentially leading to coral bleaching. Furthermore, this study underscores the significant impact on photosynthesis, growth, and the metabolic dynamics of the coral-zooxanthellae symbiotic system. Consequently, our research offers vital insights into the mortality and bleaching effects of aquatic drugs on marine corals, offering a foundation for the prudent use and management of such substances.

Tetracycline antibiotics: Potential anticancer drugs

In recent years, research on tetracycline antibiotics has gradually shifted from their antibacterial effects to anticancer effects. Doxycycline, minocycline, and tigecycline as the US Food and Drug Administration (FDA) approved tetracycline antibiotics have been the main subjects of studies. Evidence indicated that they have anticancer properties and are able to control cancer progression through different mechanisms, such as anti-proliferation, anti-metastasis, and promotion of autophagy or apoptosis. In addition, studies have shown that these three tetracycline antibiotics can be utilized in conjunction with chemotherapeutic and targeted drugs to inhibit cancer progression and improve the quality of patient survival. Therefore, doxycycline, minocycline, and tigecycline are taken as examples in this work. Their mechanisms of action in different cancers and related combination therapies are introduced. Their current roles in alleviating the suffering of patients undergoing chemotherapy when used as adjuvant drugs in clinical treatment are also described. Finally, the research gaps and potential research directions at this stage are briefly summarized.

Ribosome-binding antibiotics increase bacterial longevity and growth efficiency

Antibiotics, by definition, reduce bacterial growth rates in optimal culture conditions; however, the real-world environments bacteria inhabit see rapid growth punctuated by periods of low nutrient availability. How antibiotics mediate population decline during these periods is poorly understood. Bacteria cannot optimize for all environmental conditions because a growth-longevity tradeoff predicts faster growth results in faster population decline, and since bacteriostatic antibiotics slow growth, they should also mediate longevity. We quantify how antibiotics, their targets, and resistance mechanisms influence longevity using populations of Escherichia coli and, as the tradeoff predicts, populations are maintained for longer if they encounter ribosome-binding antibiotics doxycycline and erythromycin, a finding that is not observed using antibiotics with alternative cellular targets. This tradeoff also predicts resistance mechanisms that increase growth rates during antibiotic treatment could be detrimental during nutrient stresses, and indeed, we find resistance by ribosomal protection removes benefits to longevity provided by doxycycline. We therefore liken ribosomal protection to a "Trojan horse" because it provides protection from an antibiotic but, during nutrient stresses, it promotes the demise of the bacteria. Seeking mechanisms to support these observations, we show doxycycline promotes efficient metabolism and reduces the concentration of reactive oxygen species. Seeking generality, we sought another mechanism that affects longevity and we found the number of doxycycline targets, namely, the ribosomal RNA operons, mediates growth and longevity even without antibiotics. We conclude that slow growth, as observed during antibiotic treatment, can help bacteria overcome later periods of nutrient stress.

Analysis of possible pathways on the mechanism of action of minocycline and doxycycline against strains of Candida spp. resistant to fluconazole

Species of the genus Candida, characterized as commensals of the human microbiota, are opportunistic pathogens capable of generating various types of infections with high associated costs. Considering the limited pharmacological arsenal and the emergence of antifungal-resistant strains, the repositioning of drugs is a strategy used to search for new therapeutic alternatives, in which minocycline and doxycycline have been evaluated as potential candidates. Thus, the objective was to evaluate the in vitro antifungal activity of two tetracyclines, minocycline and doxycycline, and their possible mechanism of action against fluconazole-resistant strains of Candida spp. The sensitivity test for antimicrobials was performed using the broth microdilution technique, and the pharmacological interaction with fluconazole was also analysed using the checkerboard method. To analyse the possible mechanisms of action, flow cytometry assays were performed. The minimum inhibitory concentration obtained was 4-427 µg ml-1 for minocycline and 128-512 µg ml-1 for doxycycline, and mostly indifferent and additive interactions with fluconazole were observed. These tetracyclines were found to promote cellular alterations that generated death by apoptosis, with concentration-dependent reactive oxygen species production and reduced cell viability. Therefore, minocycline and doxycycline present themselves as promising study molecules against Candida spp.

Type I collagen proteolysis by matrix metalloproteinase-2 contributes to focal adhesion kinase activation and vascular smooth muscle cell proliferation in the aorta in early hypertension

INTRODUCTION

Increased matrix metalloproteinase (MMP)-2 activity contributes to increase vascular smooth muscle cell (VSMC) proliferation in the aorta in early hypertension by cleaving many proteins of the extracellular matrix. Cleaved products from type I collagen may activate focal adhesion kinases (FAK) that trigger migration and proliferation signals in VSMC. We therefore hypothesized that increased activity of MMP-2 proteolyzes type I collagen in aortas of hypertensive rats, and thereby, induces FAK activation, thus leading to increased VSMC proliferation and hypertrophic remodeling in early hypertension.

METHODS

Male Sprague-Dawley rats were submitted to renovascular hypertension by the two kidney-one clip (2K1C) model and treated with doxycycline (30 mg/kg/day) by gavage from the third to seventh-day post-surgery. Controls were submitted to sham surgery. Systolic blood pressure (SBP) was measured daily by tail-cuff plethysmography and the aortas were processed for zymography and Western blot for MMP-2, pFAK/FAK, integrins and type I collagen. Mass spectrometry, morphological analysis and Ki67 immunofluorescence were also done to identify collagen changes and VSMC proliferation. A7r5 cells were stimulated with collagen and treated with the MMP inhibitors (doxycycline or ARP-100), and with the FAK inhibitor PND1186 for 24 h. Cells were lysed and evaluated by Western blot for pFAK/FAK.

RESULTS

2K1C rats developed elevated SBP in the first week as well as increased expression and activity of MMP-2 in the aorta (p < 0.05 vs. Sham). Treatment with doxycycline reduced both MMP activity and type I collagen proteolysis in aortas of 2K1C rats (p < 0.05). Increased pFAK/FAK and increased VSMC proliferation (p < 0.05 vs. Sham groups) were also seen in the aortas of 2K1C and doxycycline decreased both parameters (p < 0.05). Higher proliferation of VSMC contributed to hypertrophic remodeling as seen by increased media/lumen ratio and cross sectional area (p < 0.05 vs Sham groups). In cell culture, MMP-2 cleaves collagen, an effect reversed by MMP inhibitors (p < 0.05). Increased levels of pFAK/FAK were observed when collagen was added in the culture medium (p < 0.05 vs control) and MMP and FAK inhibitors reduced this effect.

CONCLUSIONS

Increase in MMP-2 activity proteolyzes type I collagen in the aortas of 2K1C rats and contributes to activate FAK and induces VSMC proliferation during the initial phase of hypertension.

Prevalence of Brucella melitensis and Brucella abortus tetracyclines resistance: A systematic review and meta-analysis

INTRODUCTION

Brucellosis is a zoonotic disease that can be transmitted from animals to humans. Brucellosis is caused by bacteria of the genus Brucella, which are typically transmitted through contact with infected animals, unpasteurized dairy products, or airborne pathogens. Tetracyclines (tetracycline and doxycycline) are antibiotics commonly used to treat brucellosis; however, antibiotic resistance has become a major concern. This study assessed the worldwide prevalence of tetracycline-resistant Brucella isolates.

METHODS

A systematic search was conducted in Scopus, PubMed, Web of Science, and EMBASE using relevant keywords and Medical Subject Headings (MeSH) terms until August 13, 2022, to identify relevant studies for meta-analysis. A random effects model was used to estimate the proportion of resistance. Meta-regression analysis, subgroup analysis, and examination of outliers and influential studies were also performed.

RESULTS

The prevalence rates of resistance to tetracycline and doxycycline were estimated to be 0.017 (95% confidence interval [CI], 0.009-0.035) and 0.017 (95%CI, 0.011-0.026), respectively, based on 51 studies conducted from 1983 to 2020. Both drugs showed increasing resistance over time (tetracycline: r = 0.077, P = 0.012; doxycycline: r = 0.059, P = 0.026).

CONCLUSION

The prevalence of tetracycline and doxycycline resistance in Brucella was low (1.7%) but increased over time. This increase in tetracycline and doxycycline resistance highlights the need for further research to understand resistance mechanisms and develop more effective treatments.

"Slow kill" treatment reduces DNA damage in leukocytes of dogs naturally infected with Dirofilaria immitis

Parasitic diseases are considered to be a cause of oxidative stress which leads to oxidative damage of various molecules including DNA. This can result in mutations, replication errors, and genome instability. Therefore, aim of this study was to measure DNA damage induced by Dirofilaria immitis in the single cells such as dogs' leukocytes using the comet assay. Also, we monitored the effects of antiparasitic treatment on mitigation of sensitivity to DNA damage in leukocytes treated with H2O2 using the in vivo and ex vivo comet assay. The whole blood samples from 34 dogs from Serbia were used, both males and females, from one to 13 years old, both pure and mixed-breeds. A rapid immunochromatographic test (Antigen Rapid Heartworm Ag 2.0 Test Kit, Bionote, Minnesota, USA) was used for the detection of D. immitis antigens. The modified Knott's test and PCR were used in the aim of detecting D. immitis microfilariae in dogs' blood, and evaluating the number of circulating microfilariae during the treatment. The genotoxicity evaluation showed that D. immitis infection resulted in DNA damage in naturally infected dogs, with the highest DNA damage occurring in the group of dogs with severe clinical signs. Treatment with ivermectin and doxycycline decreased DNA damage in leukocytes of dogs in all groups, as the intensity of infection decreased due to applied therapy. Ex vivo comet assay results showed that leukocytes exhibited decreased sensitivity to H2O2-induced DNA damage during treatment. The results of the modified Knott's test and PCR in our study showed that treatment with ivermectin and doxycycline was successful in decreasing the average number of microfilariae during the time and at the end eliminating them from the dogs' blood.

Impact of the antibiotic doxycycline on the D. magna reproduction, associated microbiome and antibiotic resistance genes in treated wastewater conditions

Wastewater Treatment Plant (WWTP) effluents are important sources of antibiotics, antibiotic resistance genes (ARGs) and resistant bacteria that threaten aquatic biota and human heath. Antibiotic effects on host-associated microbiomes, spread of ARGs and the consequences for host health are still poorly described. This study investigated changes of the Daphnia magna associated microbiome exposed to the recalcitrant antibiotic doxycycline under artificial reconstituted lab water media (lab water) and treated wastewater media. D. magna individual juveniles were exposed for 10 days to treated wastewater with and without doxycycline, and similarly in lab water. We analysed 16 S rRNA gene sequences to assess changes in community structure, monitored Daphnia offspring production and quantified ARGs abundances by qPCR from both Daphnia and water (before and after the exposure). Results showed that doxycycline and media (lab water or wastewater) had a significant effect modulating Daphnia-associated microbiome composition and one of the most discriminant taxa was Enterococcus spp. Moreover, in lab water, doxycycline reduced the presence of Limnohabitans sp., which are dominant bacteria of the D. magna-associated microbiome and impaired Daphnia reproduction. Contrarily, treated wastewater increased diversity and richness of Daphnia-associated microbiome and promoted fecundity. In addition, the detected ARG genes in both lab water and treated wastewater medium included the qnrS1, sul1, and blaTEM, and the integron-related intI1 gene. The treated wastewater contained about 10 times more ARGs than lab water alone. Furthermore, there was an increase of sul1 in Daphnia cultured in treated wastewater compared to lab water. In addition, there were signs of a higher biodegradation of doxycycline by microbiomes of treated wastewater in comparison to lab water. Thus, results suggest that Daphnia-associated microbiomes are influenced by their environment, and that bacterial communities present in treated wastewater are better suited to cope with the effects of antibiotics.

Effect of doxycycline doped nanoparticles on osteogenic/cementogenic and anti-inflammatory responses of human cells derived from the periodontal ligament

OBJECTIVES

This work aimed to evaluate if doxycycline-doped polymeric nanoparticles possessed any anti-inflammatory effect and promote osteogenic/cementogenic differentiation of stem cells from human periodontal ligament (PDLSCs).

METHODS

The polymeric nanoparticles (NPs) were produced by a polymerization/precipitation process and doped with doxycycline (Dox-NPs). PDLSCs were cultured in the presence or absence of the NPs under osteogenic medium or IL-1β treatment. Cells' differentiation was assessed by gene expression analysis of osteogenic/cementogenic markers alkaline phosphatase (ALP) and Runt-related transcription factor 2 (RUNX2). An anti-inflammatory effect was also ascertained by analyzing IL-1β gene expression. Adipogenic and chondrogenic differentiation was used to confirm the multipotency of PDLSCs.

RESULTS

Gene expression of ALP and RUNX2 in PDLSCs was significantly upregulated by the osteogenic medium (ALP: p<0.001; RUNX2: p = 0.005) while Dox-NPs further enhanced ALP gene expression of PDLSCs treated with the osteogenic medium. Furthermore, Dox-NPs suppressed the up-regulation of IL-1β when cells were subjected to an inflammatory challenge.

CONCLUSIONS

Dox-NPs enhanced PDLSCs differentiation into osteoblasts/cementoblasts lineages while providing an anti-inflammatory effect.

CLINICAL SIGNIFICANCE

Due to their biocompatibility as well as anti-inflammatory and osteogenic/cementogenic effects, Dox-NPs are potential candidates for being used in periodontal regeneration.

The Role of Doxycycline and IL-17 in Regenerative Potential of Periodontal Ligament Stem Cells: Implications in Periodontitis

Periodontitis (PD) is a degenerative, bacteria-induced chronic disease of periodontium causing bone resorption and teeth loss. It includes a strong reaction of immune cells through the secretion of proinflammatory factors such as Interleukin-17 (IL-17). PD treatment may consider systemic oral antibiotics application, including doxycycline (Dox), exhibiting antibacterial and anti-inflammatory properties along with supportive activity in wound healing, thus affecting alveolar bone metabolism. In the present study, we aimed to determine whether Dox can affect the regenerative potential of periodontal ligament mesenchymal stem cells (PDLSCs) modulated by IL-17 in terms of cell migration, osteogenic potential, bioenergetics and expression of extracellular matrix metalloproteinase 2 (MMP-2). Our findings indicate that Dox reduces the stimulatory effect of IL-17 on migration and MMP-2 expression in PDLSCs. Furthermore, Dox stimulates osteogenic differentiation of PDLSCs, annulling the inhibitory effect of IL-17 on PDLSCs osteogenesis. In addition, analyses of mitochondrial respiration reveal that Dox decreases oxygen consumption rate in PDLSCs exposed to IL-17, suggesting that changes in metabolic performance can be involved in Dox-mediated effects on PDLSCs. The pro-regenerative properties of Dox in inflammatory microenvironment candidates Dox in terms of regenerative therapy of PD-affected periodontium are observed.

Tetracyclines resistance in Mycoplasma and Ureaplasma urogenital isolates derived from human: a systematic review and meta-analysis

BACKGROUND

Urogenital Mycoplasma infections are considered an important public health problem, owing to the presence of antibiotic resistance or decreased susceptibility, the treatment options are limited.

OBJECTIVE

Therefore, this meta-analysis aimed to estimate resistance rates of genital Mycoplasmas to tetracyclines (tetracycline, doxycycline, and minocycline).

METHODS

We searched the relevant published studies in PubMed, Scopus, and Embase until 3, March 2022. All statistical analyses were carried out using the statistical package R.

RESULTS

The 26 studies included in the analysis were performed in 15 countries. In the metadata, the proportions of tetracycline, doxycycline, and minocycline resistance in Mycoplasma and Ureaplasma urogenital isolates were reported 14.2% (95% CI 8.2-23.2%), 5% (95% CI 3-8.1%), and 11.9% (95% CI 6.3-21.5%), respectively. According to the meta-regression, the tetracycline and minocycline resistance rate decreased over time. Although, the doxycycline resistance rate increased over time. There was a statistically significant difference in the tetracyclines resistance rates between different continents/countries (P < 0.05).

CONCLUSION

The prevalence rate and antibiotic susceptibility profiles vary geographically. Therefore, rigorous or improved antimicrobial stewardship, contact tracing, and enhanced intensive surveillance systems are necessitated for preventing the emergence and further spreading of tetracyclines resistance in genital Mycoplasmas.

A Genomic Perspective on the Near-term Impact of Doxycycline Post-exposure Prophylaxis on Neisseria gonorrhoeae Antimicrobial Resistance

Pre-existing tetracycline resistance in Neisseria gonorrhoeae limits the effectiveness of post-exposure prophylaxis (PEP) with doxycycline against gonorrhea, and selection for tetracycline resistance may influence prevalence of multi-drug resistant strains. Using genomic and antimicrobial susceptibility data from N. gonorrhoeae, we assessed the near-term impact of doxycycline PEP on N. gonorrhoeae resistance.

Unveiling the Osteogenic Potential of Tetracyclines: A Comparative Study in Human Mesenchymal Stem Cells

Tetracyclines (TCs) are a class of broad-spectrum antibiotics with diverse pharmacotherapeutic properties due to their various functional groups being attached to a common core structure. Beyond their antibacterial activity, TCs trigger pleiotropic effects on eukaryotic cells, including anti-inflammatory and potentially osteogenic capabilities. Consequently, TCs hold promise for repurposing in various clinical applications, including bone-related conditions. This study presents the first comprehensive comparison of the in vitro osteogenic potential of four TCs-tetracycline, doxycycline, minocycline, and sarecycline, within human mesenchymal stem cells. Cultures were characterized for metabolic activity, cell morphology and cytoskeleton organization, osteogenic gene expression, alkaline phosphatase (ALP) activity, and the activation of relevant signaling pathways. TCs stimulated actin remodeling processes, inducing morphological shifts consistent with osteogenic differentiation. Osteogenic gene expression and ALP activity supported the osteoinduction by TCs, demonstrating significant increases in ALP levels and the upregulation of RUNX2, SP7, and SPARC genes. Minocycline and sarecycline exhibited the most potent osteogenic induction, comparable to conventional osteogenic inducers. Signaling pathway analysis revealed that tetracycline and doxycycline activate the Wnt pathway, while minocycline and sarecycline upregulated Hedgehog signaling. Overall, the present findings suggest that TCs promote osteogenic differentiation through distinct pathways, making them promising candidates for targeted therapy in specific bone-related disorders.

Development of a perfusion process for continuous lentivirus production using stable suspension producer cell lines

The large-scale production of clinical-grade lentiviral vectors (LVs) for gene therapy applications is a remaining challenge. The use of adherent cell lines and methods like transient transfection are cost-intensive and hamper process scalability as well as reproducibility. This study describes the use of two suspension-adapted stable packaging cell lines, called GPRGs and GPRTGs, for the development of a scalable and serum-free LV production process. Both stable packaging cell lines are based on an inducible Tet-off system, thus requiring doxycycline removal for initiation of the virus production. Therefore, we compared different methods for doxycycline removal and inoculated three independent 5 L bioreactors using a scalable induction method by dilution, an acoustic cell washer and manual centrifugation. The bioreactors were inoculated with a stable producer cell line encoding for a LV carrying a clinically relevant gene. LV production was performed in perfusion mode using a cell retention device based on acoustic wave separation. Comparable cell-specific productivities were obtained with all three methods and cumulative functional yields up to 6.36 × 1011 transducing units per bioreactor were generated in a 234-h long process, demonstrating the usability of stable Tet-off cell lines for an easily scalable suspension process. Remarkably, cell viabilities >90% were maintained at high cell densities without compromising productivity throughout the whole process, allowing to further extend the process time. Given its low effects of toxicity during virus production, the presented cell lines are excellent candidates to develop a fully continuous LV production process to overcome the existing bottlenecks in LV manufacturing.

Oral doxycycline to carbapenem-resistant Acinetobacter baumannii infection as a polymyxin-sparing strategy: results from a retrospective cohort

Acinetobacter baumannii infection presents a high mortality rate and few therapeutic options. This study aimed to evaluate clinical-microbiological characteristics and prognosis factors of patients diagnosed with A. baumanni. infections treated with oral doxycycline. A retrospective cohort of hospitalized patients with confirmed Acinetobacter spp. infection between 2018 and 2020 receives at least 3 days of oral doxycycline. Clinical and microbiological data were evaluated, including the outcome and molecular characterization of A. baumannii. Doxycycline minimal inhibitory concentrations were evaluated by the broth dilution method. One hundred patients were included with a median age of 51 years. The leading site of infection was pulmonary (n = 62), followed by the soft tissues and skin (n = 28). A. baumannii resistant to carbapenem was found on 94%. The gene blaOXA-23 and blaOXA-51 were amplified in all recovered isolates of A. baumannii (n = 44). Doxycycline MIC50 and MIC90 were 1 µg/mL and 2 µg/mL, respectively. Death rate at 14 days and 28 days of follow-up was 9% and 14%, respectively. The prognostic factors related to death at end of follow-up were age > 49 years [85.7% vs. 46%, CI 95% 6.9 (1.4-32.6), P = 0.015] and hemodialysis [28.6% vs. 7%, CI 95% 5.33 (1.2-22.1), P = 0.021]. Patients treated with doxycycline to A. baumannii presented a relatively low death rate, and risk factors related to death were age and hemodialysis. Further and larger studies should compare polymyxin to doxycycline to better understand the differences between these therapeutic options.

Nanoarchitectonics of doxycycline-loaded vitamin E-D-α-tocopheryl polyethylene glycol 1000 succinate micelles for ovarian cancer stem cell treatment

Aim: This study aim to develop doxycycline within the D-α-tocopheryl polyethylene glycol 1000 succinate micelle platform as an anticancer stem cell agent. Materials & methods: The optimized nanomicelle formulation was prepared using the solvent casting method and evaluated through physicochemical and biological characterization. Results: Nanomicelles exhibited mean particle sizes of 14.48 nm (polydispersity index: 0.22) using dynamic light scattering and 18.22 nm using transmission electron micrography. Drug loading and encapsulation efficiency were 2% and 66.73%, respectively. Doxycycline-loaded micelles exhibited sustained release, with 98.5% released in 24 h. IC50 values were 20 μg/ml for free drug and 5 μg/ml for micelles after 48 h of cell exposure. A significant 74% reduction in CD44 biomarker and 100% colony formation inhibition were observed. Conclusion: Doxycycline in hemo/biocompatible nanomicelles holds potential for ovarian cancer stem cell therapy.

Combining a tetracycline (Tet)-inducible gRNA system and CRISPRa for titratable and timely controlled enhancement of endogenous SHISA3 activation in human induced pluripotent stem cells (hiPSC)

Towards increasing the possibility for temporal control of gene expression using CRISPR activation (a) systems, we generated homozygous human induced pluripotent stem cell (hiPSC) lines carrying a doxycycline (dox)-inducible guide(g)-RNA construct targeting the SHISA3 transciptional start site, as proof-of-principle, or a non targeting gRNA as a control. The dox-inducible gRNA cassette was inserted into the human ROSA26 locus in a line with dCas9VPR integrated at the AAVS1 locus (CRISPRa/Tet-iSHISA3). Pluripotency, genomic integrity and differentiation potential into all three germ layers were maintained. Dox-dependent gene induction was validated in hiPSCs as well as derived fibroblasts. These lines provide an attractive tool for cellular reprogramming in hiPSC-derived cells in a timely controlled manner.