The intestinal flora of patients with GHPA affects the growth and the expression of PD-L1 of tumor

Immune landscape and progress in immunotherapy for pituitary neuroendocrine tumors

Pituitary neuroendocrine tumors (pitNETs) are the second most common primary brain tumors. Despite their prevalence, the tumor immune microenvironment (TIME) and its clinical implications remain largely unexplored. This review provides a comprehensive overview of current knowledge on the immune landscape and advancements in targeted immunotherapy for pitNETs. Macrophages and T cells are principal immune infiltrates within the TIME. Different subtypes of pitNETs display distinct immune patterns, influencing tumor progressive behaviors. PD-L1, the most extensively studied immune checkpoint, is prominently expressed in hormonal pitNETs and correlates with tumor growth and invasion. Cytokines and chemokines including interleukins, CCLs, and CXCLs have complex correlations with tumor subtypes and immune cell infiltration. Crosstalk between macrophages and pitNET cells highlights bidirectional regulatory roles, suggesting potential macrophage-targeted strategies. Recent preclinical studies have demonstrated the efficacy of anti-PD-L1 therapy in a mouse model of corticotroph pitNET. Moreover, anti-PD-1 and/or anti-CTLA-4 immunotherapy has been applied globally in 28 cases of refractory pitNETs, showing more favorable responses in pituitary carcinomas than aggressive pitNETs. In conclusion, the TIME of pitNETs represents a promising avenue for targeted immunotherapy and warrants further investigation.

Alteration in gut microbial characteristics of patients with acromegaly

PURPOSE

Studies on intestinal microbiota in acromegaly are scant. This study aimed to characterize the gut microbiome in patients with acromegaly.

METHOD

Stool samples were collected from 11 patients newly diagnosed with acromegaly and 12 healthy controls matched for body mass index (BMI) and age after three days on a standard diet. Clinical and gut microbial composition assessments were performed for the two participant groups using 16S rRNA gene amplicon sequencing.

RESULTS

There was no difference in the alpha diversity of the microbiota between the samples from patients with acromegaly and those from the healthy controls. Based on beta diversity measurements, differences in microbial community structures were found to be significant only when compared using the Jaccard similarity index. The corresponding Firmicutes/Bacteroidota ratio tended to be higher in individuals with acromegaly than in healthy controls. The mean relative abundance of Actinobacteriota was 2.3 times higher in the acromegaly patient group than in the control group. Eggerthellaceae, Christensenellaceae, and Bacteroidaceae were among the significantly abundant bacterial families in the samples from the acromegaly patient group, while Butyricicoccaceae and Tannerellaceae were decreased. At the level of the genus, the most discriminative features were the abundance of Prevotella 7, Bacteroides, Senegalimassilia, Enterohabdus, the Family XIII AD3011 group, Howardella, and Hungatella in the samples from the acromegaly patient group. In contrast, the Butyrivibrio and the Eubacterium eligens group were the most discriminative genera for the healthy controls and were significantly less abundant in patients with acromegaly. While there were no significantly differentiated taxa between the diabetic and non-diabetic subgroups, Prevotella_7 was significantly enriched in the osteoarthritis (OA) subgroup. No significant association was found between individual genera and growth hormone (GH) levels and insulin-like growth factor-1 (IGF-1) levels as well as the upper limit of normal (ULN).

CONCLUSION

Although alpha and beta diversity were mainly similar between the two groups, significant differences were observed between the acromegaly group and the control group at the family and genus levels. These results suggest that the differences between the microbial communities in patients with acromegaly and those in healthy individuals consist primarily of compositional differences independent of abundance. Prospective studies are needed to further explore the clinical implications of gut microbiome dysbiosis in patients with acromegaly.

The Role of Bacteria in Central Nervous System Tumors: Opportunities and Challenges

Tumors of the central nervous system (CNS) are severe and refractory diseases with poor prognosis, especially for patients with malignant glioblastoma and brain metastases. Currently, numerous studies have explored the potential role of bacteria and intestinal flora in tumor development and treatment. Bacteria can penetrate the blood-brain barrier (BBB), targeting the hypoxic microenvironment at the core of tumors, thereby eliminating tumors and activating both the innate and adaptive immune responses, rendering them promising therapeutic agents for CNS tumors. In addition, engineered bacteria and derivatives, such as bacterial membrane proteins and bacterial spores, can also be used as good candidate carriers for targeted drug delivery. Moreover, the intestinal flora can regulate CNS tumor metabolism and influence the immune microenvironment through the "gut-brain axis". Therefore, bacterial anti-tumor therapy, engineered bacterial targeted drug delivery, and intervention of the intestinal flora provide therapeutic modalities for the treatment of CNS tumors. In this paper, we performed a comprehensive review of the mechanisms and therapeutic practices of bacterial therapy for CNS tumors and discussed potential future research directions in this field.

Mechanism of Iron Ion Homeostasis in Intestinal Immunity and Gut Microbiota Remodeling

Iron is a vital trace element that plays an important role in humans and other organisms. It plays an active role in the growth, development, and reproduction of bacteria, such as Bifidobacteria. Iron deficiency or excess can negatively affect bacterial hosts. Studies have reported a major role of iron in the human intestine, which is necessary for maintaining body homeostasis and intestinal barrier function. Organisms can maintain their normal activities and regulate some cancer cells in the body by regulating iron excretion and iron-dependent ferroptosis. In addition, iron can modify the interaction between hosts and microorganisms by altering their growth and virulence or by affecting the immune system of the host. Lactic acid bacteria such as Lactobacillus acidophilus (L. acidophilus), Lactobacillus rhamnosus (L. rhamnosus), and Lactobacillus casei (L. casei) were reported to increase trace elements, protect the host intestinal barrier, mitigate intestinal inflammation, and regulate immune function. This review article focuses on the two aspects of the iron and gut and generally summarizes the mechanistic role of iron ions in intestinal immunity and the remodeling of gut microbiota.

Salivary microbiome profiles for different clinical phenotypes of pituitary adenomas by single-molecular long-read sequencing

IMPORTANCE

The gut and salivary microbiomes have been widely reported to be significantly associated with a number of neurological disorders. The stability of the microbiome in the oral cavity makes it a potentially ideal sample that can be conveniently obtained for the investigation of microbiome-based pathogenesis in diseases. In the present study, we used a single-molecule long-read sequencing technique to study the distribution of the salivary microbiota in patients with pituitary adenoma (PA) and healthy individuals, as well as among four clinical phenotypes of PA. We found that the diversity of salivary microbes was more abundant in PA patients than in healthy individuals. We also observed some unique genera in different PA phenotypes. The bioinformatics-based functional predictions identified potential links between microbes and different clinical phenotypes of PA. This study improves the existing understanding of the pathogenesis of PA and may provide diagnostic and therapeutic targets for PA.

PitNETs and the gut microbiota: potential connections, future directions

The role of the gut microbiome has been widely discussed in numerous works of literature. The biggest concern is the association of the gut microbiome with the central nervous system through the microbiome-brain-gut axis in the past ten years. As more and more research has been done on the relationship between the disease of the central nervous system and gut microbes. This fact is being revealed that gut microbes seem to play an important role from the onset and progression of the disease to clinical symptoms, and new treatments. As a special tumor of the central nervous system, pituitary neuroendocrine tumors (PitNETs)are closely related to metabolism, endocrinology, and immunity. These factors are the vectors through which intestinal microbes interact with the central nervous system. However, little is known about the effects of gut microbes on the PitNET. In this review, the relationship of gut microbiota in PitNETs is introduced, the potential effects of the gut-brain axis in this relationship are analyzed, and future research directions are presented.

Gut microbiota in brain tumors: An emerging crucial player

In recent decades, various roles of the gut microbiota in physiological and pathological conditions have been uncovered. Among the many interacting pathways between the host and gut flora, the gut-brain axis has drawn increasing attention and is generally considered a promising way to understand and treat brain tumors, one of the most lethal neoplasms. In this narrative review, we aimed to unveil and dissect the sophisticated mechanisms by which the gut-brain axis exerts its influence on brain tumors. Furthermore, we summarized the latest research regarding the gastrointestinal microbial landscape and the effect of gut-brain axis malfunction on different brain tumors. Finally, we outlined the ongoing developing approaches of microbial manipulation and their corresponding research related to neuro-malignancies. Collectively, we recapitulated the advances in gut microbial alterations along with their potential interactive mechanisms in brain tumors and encouraged increased efforts in this area.

Evidence for an intra-tumoral microbiome in pituitary neuroendocrine tumors with different clinical phenotypes

PURPOSE

Bacteria have been observed in the tumor environment for decades and have been demonstrated to play important roles in the pathogenesis and development of several different tumors. So far there is a clear lack of specific studies relating to the presence of bacteria in pituitary neuroendocrine tumors (PitNETs).

METHODS

In this study, we performed five region-based amplification and bacterial 16 S rRNA sequencing to identify the microbiome of PitNET tissues across four clinical phenotypes. Multiple filter procedures were performed to inhibit the risk of contamination with bacteria and bacterial DNA. Histological analysis was also conducted to validate the localization of bacteria in the intra-tumoral region.

RESULTS

We identified common and diverse bacterial types across the four clinical phenotypes of PitNET. We also predicted the potential functions of these bacteria in tumor phenotypes and found that these functions were reported in certain previous mechanistic studies. Our data indicate that the pathogenesis and development of tumors may correlate with the behavior of intra-tumoral bacteria. Histological results, including lipopolysaccharide (LPS) staining and fluorescence in situ hybridization (FISH) for bacterial 16 S rRNA clearly demonstrated the localization of bacteria in the intra-tumoral region. Staining for Iba-1 suggested that the proportion of microglia was more abundant in FISH-positive regions than in FISH-negative regions. Furthermore, in FISH-positive regions, the microglia exhibited a longitudinally branched morphology that was different to the compact morphology observed in FISH-negative regions.

CONCLUSION

In summary, we provide an evidence for the existence of intra-tumoral bacteria in PitNET.

Identification of Malassezia globosa as a Gastric Fungus Associated with PD-L1 Expression and Overall Survival of Patients with Gastric Cancer

BACKGROUND

Microbiotas affected the prognosis of cancer patients by regulating programmed death ligand-1 (PD-L1) expression. However, the relationship between gastric fungi and PD-L1 expression is still unclear in gastric cancer (GC). We aimed at exploring the association of gastric fungi with PD-L1 expression and overall survival in GC.

METHODS

A total of 61 GC patients were divided into the two groups based on the PD-L1 combined positive scores (CPS). Fungal profiling was performed by internal transcribed spacer rDNA sequencing, and the survival analyses were performed by Kaplan-Meier curves.

RESULTS

We observed a taxonomic difference of fungi between the PD-L1-High (CPS ≥ 10) and PD-L1-Low group (CPS < 10) by principal coordinates analysis (PCoA) (P = 0.014 for Bray-Curtis and P = 0.042 for Jaccard). Malassezia had a higher abundance in the PD-L1-High group compared to the PD-L1-Low group (P = 0.045). Malassezia globosa elevated significantly in the PD-L1-High group. GC patients with PD-L1 low expression and low abundance of Malassezia globosa had a longer overall survival (OS) than others (P = 0.047). Malassezia globosa was associated with PD-L1 expression (Odds Ratio = 3.509, 95% Confidence Interval: 1.056-11.656, P = 0.040). Malassezia globosa was associated with the tumor size (P = 0.031) and PD-L1 status (P = 0.024). GC patients with a high abundance of Malassezia globosa had shorter OS than others (P = 0.028). Malassezia globosa was an independent factor (Hazard Ratio = 3.080, 95% Confidence Interval: 1.140-8.323, P = 0.027) for OS after adjusting for tumor stage. Malassezia globosa was figured out to be associated with- fatty acid and lipid biosynthesis and degradation via LIPASYN pathway. Conclusions. Malassezia globosa was identified as a PD-L1 expression-associated gastric fungus and associated with OS of GC patients, which calls for more studies to further explore its potential in PD-L1/PD-1 targeted immunotherapy.

Growth hormone associated with treatment efficacy of immune checkpoint inhibitors in gastric cancer patients

Background

Immune checkpoint inhibitors (ICIs) combined with chemotherapy have been widely employed to improve the outcome of gastric cancer patients. In the present study, the impact of posttreatment growth hormone (GH) levels on the treatment efficacy of ICIs for advanced gastric cancer (AGC) patients was assessed.

Methods

Seventy-five AGC patients treated with anti-PD-1 antibodies at The Fourth Hospital of Hebei Medical University were involved. We divided AGC patients into two groups as high-GH group and low-GH group based on the GH level. Immunotherapy efficacy was assessed in terms of objective response rate, disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) based on the National Comprehensive Cancer Network Guidelines. The enumeration data were compared by χ² test or Fisher’s exact test. Survival curves were drawn by the Kaplan–Meier method, and comparisons between the curves were made using the log-rank test. Multivariate survival analysis was performed using a Cox proportional hazards model.

Results

The higher GH levels were associated with a lower DCR of ICIs with a DCR of 30.0% in the high-GH group and 53.3% in the low-GH group (P = 0.046). The subsequent univariate analysis showed that a high GH level was associated with both shorter PFS (P = 0.016) and shorter OS at the borderline statistical level (P = 0.052) in AGC patients treated with ICIs. Cox model analysis also proved that the GH level was an independent risk factor for the outcome of AGC patients (PFS: P = 0.013, HR, 2.424, 95% CI, 1.202–4.890; OS: P = 0.014, HR, 3.301, 95% CI, 1.279–8.519).

Conclusions

The post-treatment GH level might be a predictor for ICIs treatment in AGC patients.