Doxycycline hyclate: A schistosomicidal agent in vitro with immunomodulatory potential on granulomatous inflammation in vivo

Pharmacological blockade of infection chronification modulates oxy-inflammation and prevents the activation of stress-induced premature senescence markers in schistosomiasis

Chronic inflammation, oxidative stress, and DNA damage are observed in schistosomiasis and premature aging. However, the potential of these events to trigger stress-induced premature senescence (SIPS) throughout schistosomiasis progression remains overlooked, especially in response to the first-line pharmacological treatment. Thus, we investigated the relationship between oxidative stress and SIPS sentinel markers in untreated Schistosoma mansoni-infected mice and those receiving praziquantel (Pz)-based reference treatment. Swiss mice were randomized into 5 groups: uninfected (followed by 60- and 180-days post-infection), acutely (60 days) and chronically (180 days) infected untreated, and infected treated with Pz followed until 180 days. Our results indicated that infection chronification was accompanied by the worsening of hepatic granulomatous inflammation, increased number of granulomas, IL-4, TGF-β, reactive oxygen species (ROS) levels, fibrosis, hepatocytes DNA damage, upregulation in SA-β-gal activity, p16 and p21 gene expression, and hepatocytes proliferation down-regulation in the absence of telomeric shortening. These abnormalities were blocked by Pz treatment, which prevented infection chronification and the decline in hepatocytes proliferative potential, stimulating granulomatous inflammation resolution. Taken together, our findings provide the evidence that progressive fibrosis, sustained production of high ROS levels, marked DNA damage and decline in p16 and p21 expression are associated with hepatocytes replication attenuation in the chronic phase of S. mansoni infection. Thus, pharmacological blockade of infection and granulomatous inflammation is essential to prevent these premature senescence markers associated with hepatocytes replicative disorders, stimulating liver regeneration in schistosomiasis mansoni.

Dietary glycemic and energy load differentially modulates Schistosoma mansoni-induced granulomatous inflammation and response to antiparasitic chemotherapy

The impact of diet composition and energy content on schistosomiasis evolution and treatment efficacy is still controversial. This study compared the impact of sucrose-rich diet and intermittent fasting on Schistosoma mansoni infection and praziquantel (PZQ)-based chemotherapy response in mice. BALB/c mice were infected with S. mansoni and followed for 15 weeks. The animals were randomized into nine groups receiving high glycemic load (high-sucrose diet - HSD), low caloric load (standard chow alternate-day fasting - ADF), and standard chow ad libitum (AL). Eight weeks after S. mansoni infection, these groups remained untreated or were treated with PZQ (300 mg/kg/day) for 3 days. Our results indicated that parasite load (S. mansoni eggs and parasite DNA levels), granulomatous inflammation (granulomas number and size), and liver microstructural damage (reduction in hepatocytes number, increase in nucleus-cytoplasm ratio, connective stroma expansion and fibrosis) were increased in ADF-treated animals. These animals also showed decreased eggs retention, granulomatous inflammation and collagen accumulation in the small intestine. Conversely, HSD diet and PZQ treatment attenuated all these parameters and stimulated hepatic regenerative response. PZQ also stimulated fibrosis resolution in HSD-treated mice, effect that was limited ADF-exposed mice. Our findings indicate that dietary glycemic and energy load can modulate schistosomiasis progression and the severity of hepatic and intestinal granulomatous inflammation in untreated and PZQ-treated mice. Thus, lower intestinal eggs retention may potentially be linked to worsening liver disease in ADF, while attenuation of hepatic and intestinal granulomatous inflammation is consistent with reduced parasite load in HSD- and PZQ-treated animals.

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 hyclate stimulates inducible nitric oxide synthase and arginase imbalance, potentiating inflammatory and oxidative lung damage in schistosomiasis

BACKGROUND

We investigated the relationship between inducible nitric oxide synthase (iNOS) and arginase pathways, cytokines, macrophages, oxidative damage and lung granulomatous inflammation in S. mansoni-infected and doxycycline-treated mice.

METHODS

Swiss mice were randomized in four groups: (i) uninfected, (ii) infected with S. mansoni, (iii) infected + 200 mg/kg praziquantel (Pzt), (iv) and (v) infected + 5 and 50 mg/kg doxycycline. Pzt (reference drug) was administered in a single dose and doxycycline for 60 days.

RESULTS

S. mansoni-infection determined extensive lung inflammation, marked recruitment of M2 macrophages, cytokines (IL-4, IL-5, IFN-γ, TNF-α) upregulation, intense eosinophil peroxidase (EPO) levels, arginase expression and activity, reduced iNOS expression and nitric oxide (NO) production. The higher dose of doxycycline aggravated lung granulomatous inflammation, downregulating IL-4 levels and M2 macrophages recruitment, and upregulating iNOS expression, EPO, NO, IFN-γ, TNF-α, M1 macrophages, protein carbonyl and malondialdehyde tissue levels. The number and size of granulomas in doxycycline-treated animals was higher than untreated and Pzt-treated mice. Exudative/productive granulomas were predominant in untreated and doxycycline-treated animals, while fibrotic/involutive granulomas were more frequent in Pzt-treated mice. The reference treatment with Pzt attenuated all these parameters.

CONCLUSION

Our findings indicated that doxycycline aggravated lung granulomatous inflammation in a dose-dependent way. Although Th1 effectors are protective against several intracellular pathogens, effective schistosomicidal responses are dependent of the Th2 phenotype. Thus, doxycycline contributes to the worsening of lung granulomatous inflammation by potentiating eosinophils influx and downregulating Th2 effectors, reinforcing lipid and protein oxidative damage in chronic S. mansoni infection.

In vitro and in silico evaluation of the schistosomicidal activity of eugenol derivatives using biochemical, molecular, and morphological tools

Background

Eugenol shows both antibacterial and antiparasitic activities, suggesting that it might be evaluated as an option for the treatment of praziquantel-resistant schistosome.

Methods

The in vitro activities of three eugenol derivatives (FB1, FB4 and FB9) on adult worms from Schistosoma mansoni were examined by fluorescence and scanning electron microscopy to analyze effects on the excretory system and integument damage, respectively. Biochemical tests with verapamil (a calcium channel antagonist) and ouabain (a Na⁺/K⁺-ATPase pump inhibitor) were used to characterize eugenol derivative interactions with calcium channels and the Na⁺/K⁺-ATPase, while in silico analysis identified potential Na⁺/K⁺-ATPase binding sites.

Results

The compounds showed effective doses (ED₅₀) of 0.324 mM (FB1), 0.167 mM (FB4), and 0.340 mM (FB9). In addition, FB4 (0.322 mM), which showed the lowest ED_50, ED₉₀ and ED₁₀₀ (p < 0.05), caused the most damage to the excretory system and integument, according to both fluorescence and scanning electron microscopy analysis. The death of adult worms was delayed by ouabain treatment plus FB1 (192 versus 72 hours) and FB9 (192 versus 168 hours), but the response to FB4 was the same in the presence or absence of ouabain. Besides, no changes were noted when all of the eugenol derivatives were combined with verapamil. Moreover, FB1 and FB9 inhibited Na⁺/K⁺-ATPase activity according to in silico analysis but FB4 did not show a time-dependent relationship and may act on targets other than the parasite Na+/K+-ATPase.

Conclusion

Eugenol derivatives, mainly FB4 when compared to FB1 and FB9, seem to act more effectively on the integument of adult S. mansoni worms.

Doxycycline Hyclate Modulates Antioxidant Defenses, Matrix Metalloproteinases, and COX-2 Activity Accelerating Skin Wound Healing by Secondary Intention in Rats

The main objective of this study was to investigate the action of doxycycline hyclate (Dx) in the skin wound healing process in Wistar rats. We investigated the effect of Dx on inflammatory cell recruitment and production of inflammatory mediators via in vitro and in vivo analysis. In addition, we analyzed neovascularization, extracellular matrix deposition, and antioxidant potential of Dx on cutaneous repair in Wistar rats. Male animals (n = 15) were divided into three groups with five animals each (protocol: 72/2017), and three skin wounds (12 mm diameter) were created on the back of the animals. The groups were as follows: C, received distilled water (control); Dx1, doxycycline hyclate (10 mg/kg/day); and Dx2, doxycycline hyclate (30 mg/kg/day). The applications were carried out daily for up to 21 days, and tissues from different wounds were removed every 7 days. Our in vitro analysis demonstrated that Dx led to macrophage proliferation and increased N-acetyl-β-D-glucosaminidase (NAG) production, besides decreased cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and metalloproteinases (MMP), which indicates that macrophage activation and COX-2 inhibition are possibly regulated by independent mechanisms. In vivo, our findings presented increased cellularity, blood vessels, and the number of mast cells. However, downregulation was observed in the COX-2 and PGE2 expression, which was limited to epidermal cells. Our results also showed that the downregulation of this pathway benefits the oxidative balance by reducing protein carbonyls, malondialdehyde, nitric oxide, and hydrogen peroxide (H2O2). In addition, there was an increase in the antioxidant enzymes (catalase and superoxide dismutase) after Dx exposure, which demonstrates its antioxidant potential. Finally, Dx increased the number of types I collagen and elastic fibers and reduced the levels of MMP, thus accelerating the closure of skin wounds. Our findings indicated that both doses of Dx can modulate the skin repair process, but the best effects were observed after exposure to the highest dose.

Antibiotic Followed by a Potential Probiotic Increases Brown Adipose Tissue, Reduces Biometric Measurements, and Changes Intestinal Microbiota Phyla in Obesity

The development of adjuvant therapies for obesity treatment is justified by the high prevalence of this disease worldwide, and the relationship between obesity and intestinal microbiota is a promising target for obesity treatment. Therefore, this study aimed at investigating the adjuvant treatment of obesity through the use of potential probiotics and antibiotics, either separately or sequentially. In the first phase of the experiment, animals had diet-induced obesity with consumption of a high saturated fat diet and a fructose solution. After this period, there was a reduction in caloric supply, that is the conventional treatment of obesity, and the animals were divided into 5 experimental groups: control group (G1), obese group (G2), potential probiotic group (G3), antibiotic group (G4), and antibiotic followed by potential probiotic group (G5). The adjuvant treatments lasted 4 weeks and were administered daily, via gavage: Animals in G1 and G2 received distilled water, the G3 obtained Lactobacillus gasseri LG-G12, and the G4 received ceftriaxone. The G5 received ceftriaxone for 2 weeks, followed by the offer of Lactobacillus gasseri LG-G12 for another 2 weeks. Parameters related to obesity, such as biometric measurements, food consumption, biochemical tests, histological assessments, short-chain fatty acids concentration, and composition of the intestinal microbiota, were analyzed. The treatment with caloric restriction and sequential supply of antibiotics and potential probiotics was able to reduce biometric measures, increase brown adipose tissue, and alter the intestinal microbiota phyla, standing out as a promising treatment for obesity.

Doxycycline aggravates granulomatous inflammation and lung microstructural remodeling induced by Schistosoma mansoni infection

Although doxycycline exhibits immunomodulatory properties, its effects on pulmonary infection by Schistosoma mansoni remain overlooked. Thus, we investigated the impact of this drug on lung granulomatous inflammation and microstructural remodeling in a murine model of schistosomiasis. Swiss mice were randomized in four groups: (i) uninfected, (ii) infected with S. mansoni and untreated, (iii) infected treated with praziquantel (Pzq; 200 mg/kg), and (iv) infected treated with Dox (50 mg/kg). Pz was administered in a single dose, and Dox for 60 days. S. mansoni induced marked granulomatous lung inflammation, which was associated to cytokines upregulation (IL-2, IL-4, IL-10, IFN-γ, TNF-α, and TGF-β), neutrophils and macrophages recruitment, alveolar collapse, lung fibrosis, and extensive depletion of elastic fibers. These parameters were attenuated by Pzq and aggravated by Dox. Exudative/productive granulomas were predominant in untreated and Dox-treated animals, while fibrotic granulomas were more frequent in Pzq-treated mice. The number and size of granulomas in Dox-treated animals was higher than untreated and Pzq-treated mice. Dox treatment inhibited the increase in MMP-1 and MMP-2 activity but upregulated myeloperoxidase and N-acetylglucosaminidase activity compared to untreated and Pzq-treated animals. Dox and Pzq exerted no effect on elastin depletion and upregulation of elastase activity. Together, our findings indicated that Dox aggravated granulomatous inflammation, accelerating lung microstructural remodeling by downregulating MMP-1 and MMP-2 activity without impair neutrophils and macrophages recruitment or elastase activity. Thus, Dox potentiates inflammatory damage associated with lung fibrosis, elastin depletion and massive alveolar collapse, profoundly subverting lung structure in S. mansoni-infected mice.

Antiparasitic effects of ethanolic extracts of Piper arboreum and Jatropha gossypiifolia leaves on cercariae and adult worms of Schistosoma mansoni

New treatment strategies for schistosomiasis should be evaluated, since resistant strains to the only available drug, Praziquantel, have already been described. Thus, we demonstrated antiparasitic effects of ethanolic extracts of Jatropha gossypiifolia and Piper arboreum on cercariae and adult worms of Schistosoma mansoni. The bioassays were performed at 0–10 000 μg mL−1 concentration for 0–72 h. Adult worms were stained with carmine to assess external and internal damage. The chemical screening was performed using high-performance liquid chromatography. P. arboreum displayed the best cercaricidal effect, with a 100% reduction in viability in just 60 min. The extract of J. gossypiifolia was more effective against adult worms, with 100% viability reduction of male and female worms after 12 and 24 h, respectively. P. arboreum and J. gossypiifolia were equally effective in inhibiting the oviposition of S. mansoni (93% reduction) and causing damage to internal and external structures in adult worms. Flavonoids were identified in both the extracts and phenolic compounds and amides only in P. arboreum. Thus, for the first time, it was proven that ethanolic extracts of P. arboreum and J. gossypiifolia leaves are biologically active against cercariae and adult worms of S. mansoni in vitro.

Tagitinin F has anti-inflammatory, anti-nociceptive and anti-matrix metalloproteinase properties: An in silico, in vitro and in vivo study

Sesquiterpene lactones (SL) are natural bioactive molecules indicated as potential scaffolds for anti-inflammatory and analgesic drug design. However, their anti-inflammatory applicability remains underestimated since the impact of SL on inflammatory nociception and tissue repair are overlooked. Thus, we used an integrated in silico, in vitro and in vivo framework to investigate the impact of tagitinin F (TAG-F) on lipopolysaccharide (LPS)-challenged macrophages, excisional skin wounds, and carrageenan-induced paw edema and mechanical hyperalgesia in mice. RAW 264.7 macrophages in culture were challenged with LPS and treated with TAG-F (5, 10, 50 and 100 μM). The paw of BALB/c mice was injected with carrageenan and treated with 0.5% and 1% TAG-F. Excisional wounds were also produced in BALB/c mice and treated with 0.5% and 1% TAG-F. Our results indicated a consistent concentration-dependent downregulation in 5-lipoxygenase, cyclooxygenase 1 and 2 (COX-1 and COX-2), matrix metalloproteinase 1 and 2 (MMP-1 and MMP-2) activities; as well as attenuation in prostaglandin E2 (PGE2), leukotriene B4 (LTB4) and tumor necrosis factor-α (TNF-α) production in both in vitro and in vivo models. In vivo, TAG-F also attenuated carrageenan-induced paw edema and mechanical hyperalgesia in mice. From the excisional skin wound, TAG-F was still effective in reducing neutrophils and macrophages infiltration and stimulating collagen deposition in the scar tissue, accelerating tissue maturation. Together, our findings indicate that the anti-inflammatory effect of TAG-F is more comprehensive than previously suggested, exerting a significant impact on the control of edema, inflammatory pain and modulating central metabolic processes linked to skin wound healing.

Thioridazine aggravates skeletal myositis, systemic and liver inflammation in Trypanosoma cruzi-infected and benznidazole-treated mice

While thioridazine (Tio) inhibits the antioxidant defenses of Trypanosoma cruzi, the gold standard antitrypanosomal drug benznidazole (Bz) has potent anti-inflammatory and pro-oxidant properties. The combination of these drugs has never been tested to determine the effect on T. cruzi infection. Thus, we compared the impact of Tio and Bz, administered alone and in combination, on the development of skeletal myositis and liver inflammation in T. cruzi-infected mice. Swiss mice were randomized into six groups: uninfected untreated, infected untreated, treated with Tio (80 mg/kg) alone, Bz (50 or 100 mg/kg) alone, or a combination of Tio and Bz. Infected animals were inoculated with a virulent T. cruzi strain (Y) and treated by gavage for 20 days. Mice untreated or treated with Tio alone developed the most intense parasitemia, highest parasitic load, elevated IL-10, IL-17, IFN-γ, and TNF-α plasma levels, increased N-acetylglucosaminidase and myeloperoxidase activity in the liver and skeletal muscle, as well as severe myositis and liver inflammation (P < 0.05). All parameters were markedly attenuated in animals receiving Bz alone (P < 0.05). However, the co-administration of Tio impaired the response to Bz chemotherapy, causing a decrease in parasitological control (parasitemia and parasite load), skeletal muscle and liver inflammation, and increased microstructural damage, when compared to the group receiving Bz alone (P < 0.05). Altogether, our findings indicated that Tio aggravates systemic inflammation, skeletal myositis and hepatic inflammatory damage in T. cruzi-infected mice. By antagonizing the antiparasitic potential of Bz, Tio limits the anti-inflammatory, myoprotectant and hepatoprotective effects of the reference chemotherapy, aggravating the pathological remodeling of both organs. As the interaction of T. cruzi infection, Bz and Tio is potentially toxic to the liver, inducing inflammation and microvesicular steatosis; this drug combination represents a worrying pharmacological risk factor in Chagas disease.

The role of microRNAs in the pathogenesis, grading and treatment of hepatic fibrosis in schistosomiasis

Schistosomiasis is a prevalent parasitic disease worldwide. The main pathological changes of hepatosplenic schistosomiasis are hepatic granuloma and fibrosis due to worm eggs. Portal hypertension and ascites induced by hepatic fibrosis are usually the main causes of death in patients with chronic hepatosplenic schistosomiasis. Currently, no effective vaccine exists for preventing schistosome infections. For quite a long time, praziquantel (PZQ) was widely used for the treatment of schistosomiasis and has shown benefit in treating liver fibrosis. However, drug resistance and chemical toxicity from PZQ are being increasingly reported in recent years; therefore, new and effective strategies for treating schistosomiasis-induced hepatic fibrosis are urgently needed. MicroRNA (miRNA), a non-coding RNA, has been proved to be associated with the development of many human diseases, including schistosomiasis. In this review, we present a balanced and comprehensive view of the role of miRNAs in the pathogenesis, grading, and treatment of schistosomiasis-associated hepatic fibrosis. The multiple regulatory roles of miRNAs, such as promoting or inhibiting the development of liver pathology in murine schistosomiasis are also discussed in depth. Additionally, miRNAs may serve as candidate biomarkers for diagnosing liver pathology of schistosomiasis and as novel therapeutic targets for treating schistosomiasis-associated hepatic fibrosis.