Does the Spleen Have a Function in Digestion? Medical History, Phylogenetic and Embryological Development of the Splenogastric System

Targeting the cholinergic anti-inflammatory pathway: an innovative strategy for treating diseases

The cholinergic anti-inflammatory pathway (CAP) is comprised of the vagus nerve, acetylcholine, nicotinic acetylcholine receptors, the spleen, and the splenic nerve. It represents a sophisticated neuroimmune axis that critically regulates the crosstalk between the nervous system and the immune response via the vagus nerve. Here, we provided a nuanced exploration of the CAP's role in curbing inflammatory processes and its broad therapeutic potential across a spectrum of diseases. We meticulously dissect the intricate mechanisms by which the CAP modulates key signaling cascades, including the NF-κB, JAK2/STAT3, MAPK/ERK, PI3K/AKT, COX2/PGE2, and NRF2/HO-1 pathways, which are quintessential in the pathogenesis of various conditions. Additionally, we also summarized the CAP's profound implications in the management of inflammatory diseases, neurodegenerative disorders, metabolic syndromes, and oncological malignancies, elucidating its capacity to mitigate disease severity and progression through sophisticated immune modulation. The modulation of the CAP is suggested as a novel strategy that could potentially transform treatment approaches for a variety of conditions. However, the precise cellular and molecular underpinnings of the CAP's effects, as well as its translatability to clinical settings, remain subjects of ongoing investigation. The review calls for further research to demystify the mechanisms of the CAP and to harness its therapeutic potential fully, with the aim of developing innovative and efficacious treatment modalities that exploit the pathway's unique attributes.

An in-depth understanding of the role and mechanisms of T cells in immune organ aging and age-related diseases

T cells play a critical and irreplaceable role in maintaining overall health. However, their functions undergo alterations as individuals age. It is of utmost importance to comprehend the specific characteristics of T-cell aging, as this knowledge is crucial for gaining deeper insights into the pathogenesis of aging-related diseases and developing effective therapeutic strategies. In this review, we have thoroughly examined the existing studies on the characteristics of immune organ aging. Furthermore, we elucidated the changes and potential mechanisms that occur in T cells during the aging process. Additionally, we have discussed the latest research advancements pertaining to T-cell aging-related diseases. These findings provide a fresh perspective for the study of T cells in the context of aging.

Partial splenic embolization with embosphere microspheres (700-900 µm) for the treatment of hypersplenism: comparison of selective superior splenic artery embolization and inferior splenic artery embolization

OBJECTIVE

To compare clinical outcomes of superior versus inferior splenic artery embolization in partial splenic embolization (PSE) and identify predictors of major complications.

MATERIAL AND METHODS

This retrospective case-control study included 73 patients who underwent PSE between May 2005 and April 2021. They were divided into two groups: the superior and middle splenic artery embolization group (Group A, n = 37) and the inferior and middle splenic artery embolization group (Group B, n = 36). Outcome differences and major complications between the groups were assessed. Logistic regression was used to analyze potential predictors of major complications, and the optimal cutoff value for splenic embolization rates was determined using the Youden index.

RESULTS

There were no significant differences in laboratory and radiological outcomes between the two groups. Group A had a significantly lower incidence of major complications than Group B (p = 0.049), a lower Visual Analog Scale (VAS) score for pain (p = 0.036), and a shorter hospital stay (p = 0.022). Independent risk factors for major complications included inferior and middle splenic artery embolization (odds ratio [OR] = 3.672; 95% confidence interval [CI] = 1.028-13.120; p = 0.045) and a higher spleen embolization rate (OR = 1.108; 95% CI = 1.003-1.224; p = 0.044). The optimal cutoff for spleen embolization rate to predict major complications was 59.93% (sensitivity 77.8%, specificity 63.6%).

CONCLUSION

Using 500-700 µm microspheres for PSE, targeting the middle and superior splenic artery yields similar effects to targeting the middle and inferior artery, but results in lower rates of major complications and shorter hospital stays. To effectively minimize the risk of major complications, the embolization rate should be kept below 59.93%, regardless of the target vessel.

Crosstalk Between the Spleen and Other Organs/Systems: Downstream Signaling Events

The aim of this review was to gather pieces of information from available critically evaluated published articles concerning any interplay in which the spleen could be involved. For many years, the spleen has been alleged as an unnecessary biological structure, even though splenomegaly is an objective finding of many illnesses. Indeed, the previous opinion has been completely changed. In fact, the spleen is not a passive participant in or a simple bystander to a relationship that exists between the immune system and other organs. Recently, it has been evidenced in many preclinical and clinical studies that there are close associations between the spleen and other parts of the body, leading to various spleen–organ axes. Among them, the gut–spleen axis, the liver–spleen axis, the gut–spleen–skin axis, the brain–spleen axis, and the cardio-splenic axis are the most explored and present in the medical literature. Such recent sources of evidence have led to revolutionary new ideas being developed about the spleen. What is more, these observations may enable the identification of novel therapeutic strategies targeted at various current diseases. The time has come to make clear that the spleen is not a superfluous body part, while health system operators and physicians should pay more attention to this organ. Indeed, much work remains to be performed to assess further roles that this biological structure could play.

Restraint Stress-Induced Neutrophil Inflammation Contributes to Concurrent Gastrointestinal Injury in Mice

Psychological stress increases risk of gastrointestinal tract diseases. However, the mechanism behind stress-induced gastrointestinal injury is not well understood. The objective of our study is to elucidate the putative mechanism of stress-induced gastrointestinal injury and develop an intervention strategy. To achieve this, we employed the restraint stress mouse model, a well-established method to study the pathophysiological changes associated with psychological stress in mice. By orally administering gut-nonabsorbable Evans blue dye and monitoring its plasma levels, we were able to track the progression of gastrointestinal injury in live mice. Additionally, flow cytometry was utilized to assess the viability, death, and inflammatory status of splenic leukocytes, providing insights into the stress-induced impact on the innate immune system associated with stress-induced gastrointestinal injury. Our findings reveal that neutrophils represent the primary innate immune leukocyte lineage responsible for stress-induced inflammation. Splenic neutrophils exhibited elevated expression levels of the pro-inflammatory cytokine IL-1, cellular reactive oxygen species, mitochondrial burden, and cell death following stress challenge compared to other innate immune cells such as macrophages, monocytes, and dendritic cells. Regulated cell death analysis indicated that NETosis is the predominant stress-induced cell death response among other analyzed regulated cell death pathways. NETosis culminates in the formation and release of neutrophil extracellular traps, which play a crucial role in modulating inflammation by binding to pathogens. Treatment with the NETosis inhibitor GSK484 rescued stress-induced neutrophil extracellular trap release and gastrointestinal injury, highlighting the involvement of neutrophil extracellular traps in stress-induced gastrointestinal inflammation. Our results suggest that neutrophil NETosis could serve as a promising drug target for managing psychological stress-induced gastrointestinal injuries.

Neuromedin U regulates food intake of Siberian sturgeon through the modulation of central and peripheral appetite factors

Neuromedin U (NMU) has a critical function on the regulation of food intake in mammals, while the information is little in teleost. To investigate the function of NMU on appetite regulation of Siberian sturgeon (Acipenser baerii), this study first cloned nmu cDNA sequence that encoded 154 amino acids including NMU-25 peptide. Besides, the results showed that nmu mRNA was widely distributed in various tissues especially in the hypothalamus and telencephalon. The results of nutritional status (pre-feeding and post-feeding, fasting and re-feeding) experiments showed that nmu mRNA expression was significantly decreased at 1 and 3 h after feeding in different brain regions. Similarly, after feeding, the expression of nmu significantly decreased in peripheral tissues. Moreover, nmu expression in the hypothalamus was significantly increased after fasting 1 d, but decreased after fasting 17 d, which was significantly reversed after re-feeding. However, other brain regions like telencephalon and peripheral tissues like oesophagus, intestinum valvula and liver have different change patterns. Further study showed that acute i.c.v. and i.p. injection of NMU and chronic i.p. injection of NMU significantly reduced the food intake in a dose-dependent mode. In addition, the expressions of several critical appetite factors (nmu, aplein, cart, cck, ghrelin, npy, nucb2, pyy and ucn3) were significantly affected by acute NMU-25 administration in the hypothalamus, intestinum valvula and liver. These results indicate that NMU-25 has the anorexigenic function on food intake by affecting different appetite factors in Siberian sturgeon, which provides a foundation for further exploring the appetite regulation networks in fish.

Postprandial dynamics of splenic volume in healthy volunteers

Throughout the history of medicine, many functions have been attributed to the spleen and numerous researchers have focused on a postulated digestive function. Beginning in 1825, systematic animal studies showed evidence for a postprandial increase in splenic volume (SV) with a peak 30 min to five hours after food intake. Since the introduction of imaging techniques, two studies have been conducted on humans, revealing a decrease in SV 30 to 45 min postprandially. The aim of this study was to examine possible postprandial changes in SV over a period of seven hours. The ethics-approved, randomized crossover study included 10 healthy volunteers, who received a standardized meal (3,600 kJ) on one study day and fasted on the other. Sonographic measurements were obtained at six measurement points on each day. Thirty minutes after the meal, SV increased significantly by 38.2 ± 51.2 cm3 (17.3%; p = .04) compared to the baseline measurement and decreased gradually afterward. In males, SV 30 min after the meal was 70.2 ± 21.6 cm3 higher (p = .002) compared to the fasting condition and 60 min later it was still significantly increased. The apparent SV increase after food intake is discussed in relation to hemodynamic changes in the splanchnic region. It seems plausible that the spleen has a rhythmic and regulative function within the portal system, something which warrants further research and should be taken more into account in nutritional physiology.