Garlic Essential Oil as Promising Option for the Treatment of Acute Campylobacteriosis-Results from a Preclinical Placebo-Controlled Intervention Study

Effect of Garlic Straw with Silage Corn Stalks on Hu Sheep Rumen Fermentation and Microbial Community In Vitro

Garlic, an important economic crop, provides nutrient-rich straw. When appropriately balanced with silage corn stalks, it is a high-quality forage resource. However, studies on the impact of garlic straw with silage corn stalks on Hu sheep's digestive metabolism and rumen microbiota are scarce. In this study, different addition ratios of garlic straw and silage corn stalks were utilized for in vitro experiments. We designed six experimental groups (CON, G0, G20, G40, G60, G80, and G100) based on varying ratios of garlic straw to silage corn stalks. Rumen microbiota was analyzed through 16S rRNA sequencing. Nutrient composition analysis indicated that garlic straw's relative feeding value (RFV) closely resembled that of silage corn stalks. After 24 h of fermentation, dry matter digestibility and in vitro gas production significantly increased, reaching peak values at a 60% addition ratio. Furthermore, volatile fatty acids (VFAs) such as acetic, propionic, and butyric acid exhibited elevated contents, with the highest yields observed at 60% inclusion. At the genus level, Prevotella, Rikenellaceae RC9 gut group, and Succiniclasticum were identified as the dominant bacterial groups. The gas production test showed a significant decrease in the G80 group compared to others. Microbial analysis revealed a higher abundance of Prevotella in G80 compared to G20, offering valuable insights for reducing greenhouse gas emissions from ruminant animals. Finally, this study predicted the impact of garlic straw with silage corn stalks' addition on Hu sheep's metabolic pathways and biological functions of the rumen microbiota. This research highlights the potential for effectively utilizing garlic straw as a feed resource for Hu sheep and proposes a rational proportion for combining garlic straw with silage corn stalks.

Therapeutic Effects of Oral Application of Menthol and Extracts from Tormentil (Potentilla erecta), Raspberry Leaves (Rubus idaeus), and Loosestrife (Lythrum salicaria) during Acute Murine Campylobacteriosis

Human food-borne infections with the enteropathogen Campylobacter jejuni are becoming increasingly prevalent worldwide. Since antibiotics are usually not indicated in campylobacteriosis, alternative treatment regimens are important. We here investigated potential disease-alleviating effects of menthol and of extracts from tormentil, raspberry leaves, and loosestrife in acute murine campylobacteriosis. Therefore, C. jejuni-infected microbiota-depleted IL-10-/- mice were orally treated with the compounds alone or all in combination from day 2 until day 6 post-infection. Whereas neither treatment regimen affected gastrointestinal pathogen loads, the combination of compounds alleviated C. jejuni-induced diarrheal symptoms in diseased mice on day 6 post-infection. Furthermore, the therapeutic application of tormentil and menthol alone and the combination of the four compounds resulted in lower colonic T cell numbers in infected mice when compared to placebo counterparts. Notably, pro-inflammatory cytokines measured in mesenteric lymph nodes taken from C. jejuni-infected mice following tormentil, menthol, and combination treatment did not differ from basal concentrations. However, neither treatment regimen could dampen extra-intestinal immune responses, including systemic pro-inflammatory cytokine secretion on day 6 post-infection. In conclusion, the combination of menthol and of extracts from tormentil, raspberry leaves, and loosestrife constitutes an antibiotic-independent approach to alleviate campylobacteriosis symptoms.

Disease alleviating effects following prophylactic lemon and coriander essential oil treatment in mice with acute campylobacteriosis

Introduction

Given the worldwide increasing prevalence of human Campylobacter jejuni infections and the emergence of multi-drug resistant enteropathogenic strains, antibiotic-independent approaches applying non-toxic natural compounds for the treatment and prophylaxis of campylobacteriosis appear utmost desirable. In our placebo-controlled intervention study, we surveyed potential disease-alleviating including anti-pathogenic and immune-modulatory effects upon prophylactic oral application of lemon-essential oil (LEM-EO) and coriander-essential oil (COR-EO) in acute experimental campylobacteriosis.

Methods

Therefore, secondary abiotic IL-10−/− mice were orally challenged with either LEM-EO or COR-EO starting seven days prior to peroral C. jejuni infection.

Results and discussion

Six days post-infection, slightly lower pathogen loads were assessed in the colon of mice from the LEM-EO as opposed to the COR-EO cohort if compared to placebo counterparts. Prophylactic application of both EOs improved the clinical outcome of acute campylobacteriosis which was paralleled by less distinct pathogen-induced colonic epithelial cell apoptosis. Moreover, mice subjected to LEM-EO and COR-EO prophylaxis displayed lower colonic numbers of macrophages/monocytes and of T lymphocytes, respectively, whereas in both verum groups, basal IL-6 and IFN-γ concentrations were measured in mesenteric lymph nodes on day 6 post-infection. The oral challenge with either EOs resulted in diminished secretion of distinct pro-inflammatory mediators in the kidney as well as serum samples derived from the infected mice. In conclusion, the results from our preclinical in vivo study provide evidence that LEM-EO and COR-EO constitute promising prophylactic measures to prevent severe campylobacteriosis which may help to reduce the risk for development of post-infectious sequelae in C. jejuni infected individuals.

Combination of organic acids benzoate, butyrate, caprylate, and sorbate provides a novel antibiotics-independent treatment option in the combat of acute campylobacteriosis

Introduction

The food-borne Gram-negative bacterial pathogen Campylobacter jejuni may cause the acute enterocolitis syndrome campylobacteriosis in infected humans. Given that human C. jejuni infections are rising globally which hold also true for resistance rates against antibiotic compounds such as macrolides and fluoroquinolones frequently prescribed for the treatment of severe infectious enteritis, novel antibiotics-independent therapeutic strategies are needed. Distinct organic acids are well known for their health-beneficial including anti-microbial and immunomodulatory properties. In our present study, we investigated potential pathogen-lowering and anti-inflammatory effects of benzoic acid, butyric acid, caprylic acid, and sorbic acid either alone or in combination during acute murine campylobacteriosis.

Methods

Therefore, secondary abiotic IL-10–/– mice were perorally infected with C. jejuni strain 81–176 and subjected to a 4-day-course of respective organic acid treatment.

Results and discussion

On day 6 post-infection, mice from the combination cohort displayed slightly lower pathogen loads in the duodenum, but neither in the stomach, ileum nor large intestine. Remarkably, the clinical outcome of C. jejuni induced acute enterocolitis was significantly improved after combined organic acid treatment when compared to the placebo control group. In support, the combinatory organic acid treatment dampened both, macroscopic and microscopic inflammatory sequelae of C. jejuni infection as indicated by less colonic shrinkage and less pronounced histopathological including apoptotic epithelial cell changes in the colon on day 6 post-infection. Furthermore, mice from the combination as compared to placebo cohort exhibited lower numbers of innate and adaptive immune cells such as neutrophilic granulocytes, macrophages, monocytes, and T lymphocytes in their colonic mucosa and lamina propria, respectively, which also held true for pro-inflammatory cytokine secretion in the large intestines and mesenteric lymph nodes. Notably, the anti-inflammatory effects were not restricted to the intestinal tract, but could also be observed systemically given pro-inflammatory mediator concentrations in C. jejuni infected mice from the combination organic acid treatment that were comparable to basal values. In conclusion, our in vivo study provides first evidence that an oral application of distinct organic acids in combination exhibits pronounced anti-inflammatory effects and hence, constitutes a promising novel antibiotics-independent therapeutic strategy in the combat of acute campylobacteriosis.

Molecular Targets in Campylobacter Infections

Human campylobacteriosis results from foodborne infections with Campylobacter bacteria such as Campylobacter jejuni and Campylobacter coli, and represents a leading cause of bacterial gastroenteritis worldwide. After consumption of contaminated poultry meat, constituting the major source of pathogenic transfer to humans, infected patients develop abdominal pain and diarrhea. Post-infectious disorders following acute enteritis may occur and affect the nervous system, the joints or the intestines. Immunocompromising comorbidities in infected patients favor bacteremia, leading to vascular inflammation and septicemia. Prevention of human infection is achieved by hygiene measures focusing on the reduction of pathogenic food contamination. Molecular targets for the treatment and prevention of campylobacteriosis include bacterial pathogenicity and virulence factors involved in motility, adhesion, invasion, oxygen detoxification, acid resistance and biofilm formation. This repertoire of intervention measures has recently been completed by drugs dampening the pro-inflammatory immune responses induced by the Campylobacter endotoxin lipo-oligosaccharide. Novel pharmaceutical strategies will combine anti-pathogenic and anti-inflammatory effects to reduce the risk of both anti-microbial resistance and post-infectious sequelae of acute enteritis. Novel strategies and actual trends in the combat of Campylobacter infections are presented in this review, alongside molecular targets applied for prevention and treatment strategies.

Therapeutic Oral Application of Carvacrol Alleviates Acute Campylobacteriosis in Mice Harboring a Human Gut Microbiota

Human Campylobacter jejuni infections are rising globally. Since antibiotics are usually not indicated in acute campylobacteriosis, antibiotic-independent intervention measures are desirable. The phenolic compound carvacrol constitutes a promising candidate molecule given its antimicrobial and immune-modulatory features. To test the disease-alleviating effects of oral carvacrol treatment in acute murine campylobacteriosis, IL-10^-/- mice harboring a human gut microbiota were perorally infected with C. jejuni and treated with carvacrol via the drinking water. Whereas C. jejuni stably established in the gastrointestinal tract of mice from the placebo cohort, carvacrol treatment resulted in lower pathogen loads in the small intestines on day 6 post infection. When compared to placebo, carvacrol ameliorated pathogen-induced symptoms including bloody diarrhea that was accompanied by less distinct histopathological and apoptotic cell responses in the colon. Furthermore, innate and adaptive immune cell numbers were lower in the colon of carvacrol- versus placebo-treated mice. Notably, carvacrol application dampened C. jejuni-induced secretion of pro-inflammatory mediators in intestinal, extra-intestinal and systemic organs to naive levels and furthermore, resulted in distinct shifts in the fecal microbiota composition. In conclusion, our preclinical placebo-controlled intervention study provides evidence that therapeutic carvacrol application constitutes a promising option to alleviate campylobacteriosis in the infected vertebrate host.

Iron Deprivation by Oral Deferoxamine Application Alleviates Acute Campylobacteriosis in a Clinical Murine Campylobacter jejuni Infection Model

The progressively rising food-borne Campylobacter jejuni infections pose serious health problems and socioeconomic burdens. Given that antibiotic therapy is not recommended for most campylobacteriosis patients, novel treatment options include strategies targeting iron homeostasis that impacts both C. jejuni virulence and inflammatory cell damage caused by toxic oxygen species. In our preclinical intervention study, we tested potential disease-alleviating effects upon prophylactic oral application of the iron-chelating compound desferoxamine (DESF) in acute murine campylobacteriosis. Therefore, microbiota-depleted IL-10^-/- mice received synthetic DESF via the drinking water starting seven days before oral infection with C. jejuni strain 81-176. Results revealed that the DESF application did not reduce gastrointestinal pathogen loads but significantly improved the clinical outcome of infected mice at day 6 post-infection. This was accompanied by less pronounced colonic epithelial cell apoptosis, attenuated accumulation of neutrophils in the infected large intestines and abolished intestinal IFN-γ and even systemic MCP-1 secretion. In conclusion, our study highlights the applied murine campylobacteriosis model as suitable for investigating the role of iron in C. jejuni infection in vivo as demonstrated by the disease-alleviating effects of specific iron binding by oral DESF application in acute C. jejuni induced enterocolitis.

Less Pronounced Immunopathological Responses Following Oral Butyrate Treatment of Campylobacter jejuni-Infected Mice

Given that human Campylobacter jejuni infections are rising globally and antibiotic treatment is not recommended, infected patients would substantially benefit from alternative therapeutic strategies. Short-chain fatty acids such as butyrate are known for their health benefits, including anti-microbial and anti-inflammatory effects. This prompted us to investigate potential disease-alleviating properties of butyrate treatment during acute murine C. jejuni-induced enterocolitis. Therefore, following gut microbiota depletion IL-10^−/− mice were challenged with 10⁹ viable C. jejuni cells by oral gavage and treated with butyrate via the drinking water (22 g/L) starting on day 2 post-infection. As early as day 3 post-infection, butyrate reduced diarrheal severity and frequency in treated mice, whereas on day 6 post-infection, gastrointestinal C. jejuni burdens and the overall clinical outcomes were comparable in butyrate- and placebo-treated cohorts. Most importantly, butyrate treatment dampened intestinal pro-inflammatory immune responses given lower colonic numbers of apoptotic cells and neutrophils, less distinct TNF-α secretion in mesenteric lymph nodes and lower IL-6 and MCP-1 concentrations in the ileum. In conclusion, results of our preclinical intervention study provide evidence that butyrate represents a promising candidate molecule for the treatment of acute campylobacteriosis.

Disease-Alleviating Effects of Peroral Activated Charcoal Treatment in Acute Murine Campylobacteriosis

Foodborne Campylobacter jejuni infections are on the rise and responsible for worldwide serious health issues. Increasing resistance of C. jejuni strains against antimicrobial treatments, necessitates antibiotics-independent treatment options for acute campylobacteriosis. Activated charcoal (AC) constitutes a long-known and safe compound for the treatment of bacterial enteritis. In this preclinical intervention study, we addressed potential anti-pathogenic and immune-modulatory effects of AC during acute experimental campylobacteriosis. Therefore, microbiota-depleted IL-10^-/- mice were infected with C. jejuni by gavage and challenged with either AC or placebo via the drinking water starting on day 2 post-infection. On day 6 post-infection, AC as compared to placebo-treated mice did not only harbor lower intestinal pathogen loads but also presented with alleviated C. jejuni-induced clinical signs such as diarrhea and wasting symptoms. The improved clinical outcome of AC-treated mice was accompanied by less colonic epithelial cell apoptosis and reduced pro-inflammatory immune responses in the intestinal tract. Notably, AC treatment did not only alleviate intestinal, but also extra-intestinal and systemic immune responses as indicated by dampened pro-inflammatory mediator secretion. Given the anti-pathogenic and immune-modulatory properties of AC in this study, a short-term application of this non-toxic drug constitutes a promising antibiotics-independent option for the treatment of human campylobacteriosis.