Mesenteric lymph duct drainage attenuates acute lung injury in rats with severe intraperitoneal infection

Gut lymph purification alleviates acute lung injury induced by intestinal ischemia-reperfusion in rats by removing danger-associated molecular patterns from gut lymph

Background

The potential effect of removing danger-associated molecular patterns (DAMPs) from gut lymph on reducing acute lung injury (ALI) induced by gut ischemia-reperfusion injury (GIRI) is uncertain. This study aimed to investigate whether gut lymph purification (GLP) could improve GIRI-induced acute lung injury in rats by clearing danger-associated molecular patterns.

Materials and methods

Rats were divided into four groups: Sham, GIRI, GIRI + gut lymph drainage (GLD), and GIRI + GLP. After successful modeling, lung tissue samples were collected from rats for hematoxylin-eosin (HE) staining and detection of apoptotic indexes. We detected the DAMPs levels in blood and lymph samples. We observed the microstructure of AEC Ⅱ and measured the expression levels of apoptosis indexes.

Results

The GIRI group showed destruction of alveolar structure, thickened alveolar walls, and inflammatory cell infiltration. This was accompanied by significantly increased levels of high mobility group protein-1 (HMGB-1) and Interleukin-6 (IL-6), while reduced levels of heat shock protein 70 (HSP 70) and Interleukin-10 (IL-10) in both lymph and serum. In contrast, the lung tissue damage in the GIRI + GLP group was significantly improved compared to the GIRI group. This was evidenced by a reduction in the expression levels of HMGB-1 and IL-6 in both lymph and serum and an increase in HSP 70 and IL-10 levels. Additionally, organelle structure of AEC II was significantly improved in the GIRI + GLP group compared to the GIRI group.

Conclusions

GLP inhibits inflammation and cell apoptosis in GIRI-induced ALI by blocking the link between DAMPs and mononuclear phagocytes, reducing the severity of ALI.

Intestinal Lymphatic Dysfunction in Kidney Disease

Kidney disease is associated with adverse consequences in many organs beyond the kidney, including the heart, lungs, brain, and intestines. The kidney-intestinal cross talk involves intestinal epithelial damage, dysbiosis, and generation of uremic toxins. Recent studies reveal that kidney injury expands the intestinal lymphatics, increases lymphatic flow, and alters the composition of mesenteric lymph. The intestinal lymphatics, like blood vessels, are a route for transporting potentially harmful substances generated by the intestines. The lymphatic architecture and actions are uniquely suited to take up and transport large macromolecules, functions that differentiate them from blood vessels, allowing them to play a distinct role in a variety of physiological and pathological processes. Here, we focus on the mechanisms by which kidney diseases result in deleterious changes in intestinal lymphatics and consider a novel paradigm of a vicious cycle of detrimental organ cross talk. This concept involves kidney injury-induced modulation of intestinal lymphatics that promotes production and distribution of harmful factors, which in turn contributes to disease progression in distant organ systems.

Medical and Surgical Implications of Mesenteric Adipose Tissue in Crohn's Disease: A Review of the Literature

Mesenteric adipose tissue (MAT) has gained substantial attention as an active player in Crohn's disease (CD), but its clinical significance is poorly understood and likely reflects, in part, difficulties assessing MAT noninvasively. Recent radiologic studies have identified candidate surrogate markers that may reflect inflammatory alterations of MAT in CD and have found that certain features including visceral adipose tissue may inform risk of complicated disease behavior, risk for surgery, and postoperative outcomes. Additionally, emerging surgical data have suggested MAT may even be a therapeutic target to mitigate postoperative recurrence of CD. However, the current studies have variable results, reduced sample sizes, and methodological limitations that preclude incorporating the radiologic and surgical findings into clinical practice. Nonetheless, the results are promising and potentially have important implications for the medical and surgical management of CD, which merits that additional studies are warranted. Thus, we have reviewed the available literature on the medical and surgical implications of MAT in CD to summarize our current understanding and identify gaps in knowledge to inform future investigations.

Mesenteric Lymph Duct Ligation Alleviates Acute Lung Injury Caused by Severe Acute Pancreatitis Through Inhibition of High Mobility Group Box 1-Induced Inflammation in Rats

BACKGROUND

Acute lung injury (ALI) is the most common complication and one of the leading causes of mortality of severe acute pancreatitis (SAP). Nevertheless, no effective therapeutic schemes are presently available.

AIMS

To investigate the effect and potential mechanism of mesenteric lymph duct ligation (MLDL) on experimental SAP-induced ALI.

METHODS

Immediately following MLDL, rats were subjected to SAP by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. At 24 h after modeling, tissues were collected for morphological examination. The levels of TNF-α, IL-6, intercellular adhesion molecule-1 (ICAM1), diamine oxidase (DAO), and D-lactic acid (D-LA) in serum, and the myeloperoxidase (MPO) activity in lung tissues were determined. Moreover, the expressions of high mobility group box 1 (HMGB1), receptor of advanced glycation endproducts (RAGE), and NF-κB p65 at the mRNA and protein levels in lung tissues, and the expressions of HMGB1, RAGE, and TNF-α at the mRNA level in intestinal lymphoid tissues were evaluated.

RESULTS

MLDL significantly attenuated the histological injury of the pancreas and lung and reduced the production of TNF-α, IL-6, and ICAM1. Besides, MLDL repressed the activity of MPO in the lung. However, the levels of serum DAO and D-LA were decreased without obvious morphological improvement in intestinal injury. Moreover, MLDL apparently reduced the up-regulation of HMGB1, RAGE, and NF-κB p65 in lung tissues, as well as the expressions of HMGB1, RAGE, and TNF-α in intestinal lymphoid tissues.

CONCLUSIONS

Mesenteric lymph was a source of harmful factors leading to SAP-ALI. MLDL could alleviate SAP-ALI probably by inhibiting HMGB1-induced production of inflammation factors.

Fluid resuscitation via colon alleviates systemic inflammation in rats with early-stage severe acute pancreatitis

Fluid resuscitation via colon (FRVC) is a complementary therapeutic procedure for early-stage cases of severe acute pancreatitis (SAP). The expression of intestinal dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) regulates systemic inflammation. This study aimed to investigate the effect of FRVC on the expression of DC-SIGN in the colon tissue of SAP rats and its effect on the early response of systemic inflammatory and multiple organ injury. SAP was induced in rats via retrograde injection of sodium taurocholate into the biliopancreatic duct. DC-SIGN expression of appeared in the proximal and distal colon. Histological characteristics and inflammatory cytokines were examined to compare the effect of FRVC and intravenous fluid resuscitation (IVFR). The results showed that DC-SIGN expression in the proximal colon increased in a time-dependent manner in the early-stage of SAP rats. FRVC inhibited DC-SIGN expression in the proximal colon. Both FRVC and IVFR alleviated histological injuries of the pancreas and colon. However, FRVC had an advantage over IVFR in alleviating lung injury and reducing serum TNF-α, IL-6 and LPS. These results suggest that FRVC treatment might help suppress systemic inflammation and prevent subsequent organ failure in early-stage SAP rats likely through inhibiting DC-SIGN expression in the proximal colon.

Gut-lymph-lung pathway mediates sepsis-induced acute lung injury

This review attempts to unveil the possible mechanisms underlying how gut lymph affects lung and further gives rise to acute respiratory distress syndrome, as well as potential interventional targets under the condition of ischemia-reperfusion injury. We searched electronic databases including PubMed, MEDLINE, Cochrane Central Register of Controlled Trials, Google Scholar, Web of Science, and Embase to identify relevant literatures published up to December 2019. We enrolled the literatures including the Mesh Terms of “gut lymph or intestinal lymph and acute lung injury or acute respiratory distress syndrome.” Gut is considered to be the origin of systemic inflammation and the engine of multiple organ distress syndrome in the field of critical care medicine, whereas gut lymph plays a pivotal role in initiation of ischemia-reperfusion injury-induced acute respiratory distress syndrome. In fact, in the having been established pathologic model of sepsis leading to multiple organ dysfunction named by Gut Lymph theory, a variety of literatures showed the position and role of changes in gut lymph components in the initiation of systemic inflammatory response, which allows us to screen out potential intervention targets to pave the way for future clinic and basic research.

Pathophysiology of sepsis

PURPOSE OF REVIEW

To provide a current overview of sepsis pathophysiology.

RECENT FINDINGS

The emphasis on sepsis pathophysiology has moved away from the pathogen - the initiating factor - and instead is focussed upon the abnormal and exaggerated host response. Instead of targeted eradication of the infection, the host response activates or suppresses multiple downstream pathways, leading to multiple organ dysfunction.

SUMMARY

Sepsis represents a dysregulated host response to infection leading to organ dysfunction. Here, the pathogen triggers an initial exaggerated inflammatory-immune response that leads to activation or suppression of multiple endothelial, hormonal, bioenergetic, metabolic, immune, and other pathways. These, in turn, produce the circulatory and metabolic perturbations resulting in organ dysfunction. This review will provide an overview of underlying mechanisms and propose that these processes, whereas superficially viewed as dysfunctional, may actually be adaptive/protective in the first instance, though spilling over into maladaptation/harm depending on the magnitude of the host response.

The Gut-Lung Axis in Systemic Inflammation. Role of Mesenteric Lymph as a Conduit

Emerging evidence shows that after injury or infection, the mesenteric lymph acts as a conduit for gut-derived toxic factors to enter the blood circulation, causing systemic inflammation and acute lung injury. Neither the cellular and molecular identity of lymph factors nor their mechanisms of action have been well understood and thus have become a timely topic of investigation. This review will first provide a summary of background knowledge on gut barrier and mesenteric lymphatics, followed by a discussion focusing on the current understanding of potential injurious factors in the lymph and their mechanistic contributions to lung injury. We also examine lymph factors with antiinflammatory properties as well as the bidirectional nature of the gut-lung axis in inflammation.

Gut Ischemia Reperfusion Injury Induces Lung Inflammation via Mesenteric Lymph-Mediated Neutrophil Activation

Gut ischemia/reperfusion (I/R) injury is a common clinical problem associated with significant mortality and morbidities that result from systemic inflammation and remote organ dysfunction, typically acute lung injury. The mechanisms underlying the dissemination of gut-derived harmful mediators into the circulation are poorly understood. The objective of our study was to determine the role of mesenteric lymphatic circulation in the systemic and pulmonary inflammatory response to gut I/R. Using a murine intestinal I/R model, we evaluated whether and how blocking mesenteric lymph flow affects the inflammatory response in local tissues (gut) and remote organs (lungs). We further explored the mechanisms of post-I/R lymph-induced systemic inflammation by examining neutrophil activity and interaction with endothelial cells in vitro. Mice subjected to intestinal I/R displayed a significant inflammatory response in local tissues, evidenced by neutrophil infiltration into mucosal areas, as well as lung inflammation, evidenced by increased myeloperoxidase levels, neutrophil infiltration, and elevated microvascular permeability in the lungs. Mesenteric lymph duct ligation (MLDL) had no effect on gut injury per se, but effectively attenuated lung injury following gut I/R. Cell experiments showed that lymph fluid from post-I/R animals, but not pre-I/R, increased neutrophil surface CD11b expression and their ability to migrate across vascular endothelial monolayers. Moreover, post-I/R lymph upregulated neutrophil expression of pro-inflammatory cytokines and chemokines, which was mediated by a mechanism involving nuclear factor (NF)-κB signaling. Consistently, gut I/R activated NF-κB in lung neutrophils, which was alleviated by MLDL. In conclusion, all these data indicate that mesenteric lymph circulation contributes to neutrophil activation and lung inflammation following gut I/R injury partly through activating NF-κB.

Effect of regulation of peritoneal lymphatic stomata on endotoxin induced lung injury in rats with early abdominal infection

AIM: To investigate the effect of regulation of peritoneal lymphatic stomata on endotoxin induced lung injury in early abdominal infection.

METHODS: Fifty-four Wister rats were randomly divided into three groups: a control group (n = 18) to receive sham operation and intraperitoneal injection of saline solution, an experimental group (n = 18) to receive intraperitoneal ligation perforation (CLP) and cecum injection of saline solution, and an intervention group (n = 18) to receive CLP and intraperitoneal injection of losartan potassium 1.0 h before and 0.5 and 2.0 h after surgery. The aperture size and density of peritoneal lymphatic stomata, lymph endotoxin concentration, immunohistochemical average optical density of nuclear factor κB (NF-κB) P65 in lung tissue, and relative Caspase3 protease activity in lung tissue were measured and compared for the three groups.

RESULTS: As time went by, peritoneal lymphatic stomata aperture and density and lymph endotoxin concentration gradually increased in the experimental group (P < 0.05). In the intervention group, lymphatic stomata and endotoxin indexes were significantly higher after operation than before operation, and at 2.0 h after operation than at 0.5 h (P < 0.05). NF-κB P65 expression and Caspase3 activity in lung tissue were also significantly higher after operation than before operation, and at 2.0 h after operation than at 0.5 h (P < 0.05).

CONCLUSION: In early abdominal infection, angiotensin Ⅱ receptor (AngⅡ-R) inhibitor can regulate the peritoneal lymphatic stomata and reduce lung injury caused by endotoxin. Earlier intervention is associated with milder lung injury. s