Diverticular disease refers to a spectrum of alterations in the intestinal tract; that begins with diverticulosis, or herniation of mucosa and submucosa through the muscle layer of the colon wall, commonly in regions where the mural blood vessels penetrate through the muscle layer of the colon wall (Kleessen et al. 1999). In terms of diverticulitis pathogenesis, it has been proposed that; diverticulitis develops from obstruction of a diverticulum's neck, resulting in bacterial proliferation, local ischemia, and micro-perforation (Jacobs 2007). Thus, dysbiosis is considered to be an important determinant in the pathogenesis of diverticulitis; since the imbalance in the microbial milieu leads to disruption of the immune homeostasis and causes intestinal diseases (Chassaing and Darfeuille-Michaud 2011). Otherwise, the interactions between the intestinal flora and the host immune system have a critical role in the prevention of intestinal diseases, where the commensal microbiome enhances the maturation of the mucosal immune system, whereas the pathogenic microbiome causes immunity dysfunction; which leads to disease development (Shi et al. 2017). As a consequence, using antibiotics or probiotics to manipulate the gut microbiota composition has recently been recommended as a therapeutic strategy for acute diverticulitis disease. Antibiotics have long been the cornerstone for the management of acute diverticulitis, intending to prevent inflammation and alleviate associated symptoms (Hanna and Kaiser 2021).
In this study, we showed that amoxicillin (especially together with probiotics) had protective effects on DSS/LPS-induced diverticulitis. DSS induces intestinal inflammation, which damages the epithelial monolayer lining the large intestine, allowing the dissemination of pro-inflammatory intestinal contents (e.g. bacteria and their products) into the underlying tissue (Chassaing et al. 2014). Furthermore, LPS aggravates colon inflammation (Zhang et al. 2011). In this study, DSS together with LPS enema gave rise to a significant decrease in the rats’ body weights. This loss in body weight is due to a deficiency of nutrients resulting from food aversion, reduced appetite, malabsorption, as well as loss of body fluids through colorectal bleeding and diarrhea (Hunschede et al. 2017). Also, there was an increase in the colon weight-to-length ratio due to tissue edema, necrosis, and inflammatory cell infiltration confirmed in our study through the high macroscopic and microscopic lesion scores. These results agreed with Peran et al. (2007) and Khodir et al. (2019). Also, Mahoro et al. (2021) found that; DSS induced bloody diarrhea, weight loss, shortening of the colon, and mucosal deterioration in a rat model of DSS-induced colitis. Otherwise, only treatment with amoxicillin together with probiotics could significantly ameliorate the body weight loss caused by DSS/LPS, while both treatments (amoxicillin and probiotics-amoxicillin) showed inhibitory effects on the high colon weight-to-length ratio (p < 0.01), as well as colon macroscopic lesion score (p < 0.001). Applegate et al. (2010) clarified that; treatment with probiotics results in bacterial antagonism, colonization competition, and emulation for nutrients. These actions lead to amelioration of toxic compounds, modulation of the immune system, increasing nutrient absorption and digestibility, and ultimately decline in the body weight loss. Lactobacillus and Bifidobacterium strains have anti-inflammatory and immunomodulatory activities. Moreover, certain Lactobacillus strains can upregulate the expression of mucin-3 and enhance the intestinal mucus layer (Yao et al 2017), so they could inhibit DSS/LPS-induced damage in the colon tissue.
MPO is a member of the peroxidases subfamily and has more expression in immune cells such as neutrophils, lymphocytes, monocytes, and macrophages. The enhanced level of MPO activity is a well diagnostic marker of inflammation and oxidative stress (Khan et al. 2018). In this study, combined treatment of probiotics and amoxicillin was more effective than amoxicillin alone in ameliorating the elevated MPO activity caused by DSS/LPS. This amelioration is due to the anti-inflammatory properties. The decrease in this enzyme activity reveals a lower infiltration of neutrophils in the inflamed colon tissue; since treatment with probiotics caused a reduction in the colonic production of the chemotactic eicosanoid LTB4. It was observed that; Lactobacillus acidophilus administration reduced colonic MPO activity in the trinitrobenzene sulfonic acid (TNBS) model of rat colitis (Peran et al. 2007).
CRP is one of the most prominent proteins in acute inflammation (Norouzinia et al. 2017). It has been found that; higher levels of CRP, as well as the inflammatory markers, have been detected in patients with severe acute diverticulitis disease (Lahat et al. 2019). In the present study, DSS/LPS administration caused a significant elevation (p < 0.001) in the serum level of CRP. This elevation was declined on either treatment with amoxicillin or probiotics-amoxicillin due to the inhibition of inflammation and disease progression. According to Sartelli et al. (2020), CRP is a valuable biomarker of inflammation and can be used in the prediction of the severity of acute diverticulitis. Furthermore, the current study revealed that DSS/LPS resulted in an elevation of the levels of TNF-α, IL-1β, IFN-γ, and IL-18. Pro-inflammatory cytokines such as IL-1β and TNF-α have been involved in the inflammatory process in DSS-induced colitis (Triantafillidis et al. 2011). Lahat et al. (2019) demonstrated that; patients with severe acute diverticulitis have higher tissue inflammatory cytokine levels including TNF-α, IL-6, IL-1β, and more inflammatory infiltrates in diverticular colon tissue. On the other hand, the elevation in TNF-α, IL-1β, IFN-γ, and IL-18 levels was significantly declined on treatment with amoxicillin or probiotics-amoxicillin. This inhibitory effect is attributed to the existence of a cross-talk between probiotics and mucosal cells. Bifidobacterium lactis, either alone or in combination with other probiotics, was able to downregulate the degree of activation of intestinal immune cells in the TNBS model of rat colitis (Peran et al. 2007). Probiotics may restore the balance of gut flora by decreasing pathogenic gram-negative bacteria; that may have been altered in diverticular disease due to stasis and reduced colonic transit time, and have been proposed to be used in diverticular disease to prevent inflammation (Boynton and Floch 2013).
The biochemical analysis and the colonic macroscopic lesions evaluation were confirmed by the histological study, where DSS/LPS caused mucosal and submucosal inflammatory cells infiltration, dilated blood vessels, and degenerative mucosal changes with damaged crypts. Both Schieffer et al. (2018) and Tursi et al. (2020) demonstrated similar changes that occurred in the architecture of the colon wall, including loss of elasticity function and deposition of immature collagen fibers in the extracellular matrix, which are implicated in the formation of diverticula as part of the pathophysiology of diverticular disease. Treatment with probiotics-amoxicillin was more effective than treatment with amoxicillin alone in improving the architecture of the colon tissue since the colon tissues showed slight inflammation and few mucosal lymphocytes infiltration on probiotics-amoxicillin treatment while showed few mucosal and submucosal inflammatory cells infiltration and degenerative mucosal changes with few damaged crypts on amoxicillin treatment. Conclusively, antibiotics have been used to treat acute diverticulitis in all patients. Recent findings have indicated that; the manipulation of antibiotics is not necessary for mild or moderate uncomplicated acute diverticulitis management, as was initially thought (Feuerstein and Falchuk 2016). Treatment of acute diverticulitis generally comprises dietary fiber supplementation, anti-inflammatory drugs, pharmacological therapies such as antibiotics, as well as probiotics, either alone or in combination (Tursi et al. 2015).
The present study revealed that each of the treatments attenuated the severity of DSS/LPS-induced acute diverticulitis in rats and displayed differing effectiveness in disease parameters. Combined probiotics-amoxicillin therapy was more effective in restoring the rats’ body weight, inhibiting the inflammatory markers tested in this study, and improving the epithelium damage score. Further studies are required in order to understand how probiotics can be employed in treating acute diverticulitis. The impact of the intestinal milieu, especially enteric microbiota, appears to be of great significance. Our study demonstrates that; probiotics enhanced the prevention of DSS/LPS-induced acute diverticulitis, so we suggest employing probiotics in treating acute diverticulitis disease.