The paradoxical effects of splenectomy on tumor growth

Splenectomy has opposite effects on the growth of primary compared with metastatic tumors in a murine colon cancer model

The spleen is a key source of circulating and tumor-infiltrating immune cells. However, the effect of splenectomy on tumor growth remains unclear. At 3 weeks after splenectomy, we subcutaneously injected LuM1 cells into BALB/c mice and evaluated the growth of primary tumors and lung metastases at 4 weeks after tumor inoculation. In addition, we examined the phenotypes of immune cells in peripheral blood by using flow cytometry and in tumor tissue by using multiplex immunohistochemistry. The growth of primary tumors was reduced in splenectomized mice compared with the sham-operated group. Conversely, splenectomized mice had more lung metastases. Splenectomized mice had fewer CD11b+cells, especially monocytic MDSCs (CD11b+Gr-1neg-lowLy6chigh), and NK cells (CD49b+CD335+). The proportion of NK cells was inversely correlated with the number of lung metastases. In splenectomized mice, the density of CD3+ and granzyme B+ CD8+ T cells was increased, with fewer M2-type macrophages in primary tumors, but NK cells were decreased markedly in lung. Splenectomy concurrently enhances T cell-mediated acquired immunity by reducing the number of monocytic MDSCs and suppresses innate immunity by decreasing the number of NK cells. Splenectomy has opposite effects on primary and metastatic lesions through differential regulation on these two immune systems.

Splenectomy as Part of Maximal-Effort Cytoreductive Surgery in Advanced Epithelial Ovarian Cancer

INTRODUCTION

A splenectomy is frequently performed during debulking surgery for advanced ovarian cancer. Its impact on perioperative and survival outcomes remains questionable as current evidence is conflicting. In the present study, we sought to determine the factors that affect survival rates in ovarian cancer patients that undergo a splenectomy as part of maximal-effort cytoreduction.

PATIENTS AND METHODS

A retrospective chart review was conducted that included all epithelial ovarian cancer patients that had surgical cytoreduction for advanced epithelial ovarian cancer. Differences among splenectomized and non splenectomized patients were evaluated as well as the impact of known risk factors on survival outcomes of splenectomized patients.

RESULTS

Overall, 245 patients were identified and 223 were included in the present series, of whom 91 had a splenectomy. Recurrence rates as well as death rates were comparable among splenectomized and non-splenectomized patients; however, both the disease-free survival (log-rank = 0.001), as well as the overall survival of splenectomized patients (log-rank = 0.006), was shorter. Thrombotic events as well as rates of pulmonary embolism were comparable. Sepsis was more common among splenectomized patients. The site of splenic metastases did not influence patients' survival. Among splenectomized patients, those offered primary debulking had longer progression-free survival (log-rank = 0.042), although their overall survival did not differ compared to patients submitted to interval debulking. Complete debulking significantly improved the overall survival compared to optimal debulking (log-rank = 0.047). Splenectomized patients that developed sepsis had worse overall survival (log-rank = 0.005).

DISCUSSION

The findings of our study support the feasibility of splenectomy in advanced epithelial ovarian cancer; however, its impact on patients' survival is considerable. Therefore, every effort should be made to avoid splenic injury which will result in unintended splenectomy for non-oncological reasons.

Hematologic dysfunction in cancer: Mechanisms, effects on antitumor immunity, and roles in disease progression

With the major advances in cancer immunology and immunotherapy, it is critical to consider that most immune cells are short-lived and need to be continuously replenished from hematopoietic stem and progenitor cells. Hematologic abnormalities are prevalent in cancer patients, and many ground-breaking studies over the past decade provide insights into their underlying cellular and molecular mechanisms. Such studies demonstrate that the dysfunction of hematopoiesis is more than a side-effect of cancer pathology, but an important systemic feature of cancer disease. Here we review these many advances, covering the cancer-associated phenotypes of hematopoietic stem and progenitor cells, the dysfunction of myelopoiesis and erythropoiesis, the importance of extramedullary hematopoiesis in cancer disease, and the developmental origins of tumor associated macrophages. We address the roles of many secreted mediators, signaling pathways, and transcriptional and epigenetic mechanisms that mediate such hematopoietic dysfunction. Furthermore, we discuss the important contribution of the hematopoietic dysfunction to cancer immunosuppression, the possible avenues for therapeutic intervention, and highlight the unanswered questions and directions for future work. Overall, hematopoietic dysfunction is established as an active component of the cancer disease mechanisms and an important target for therapeutic intervention.

Immunomodulatory effect of splenectomy in lung cancer mouse xenograft models receiving radiation therapy

Purpose: This study aims to investigate the effect of splenectomy on radiation-mediated growth inhibition and immune modulation in lung cancer xenograft models. Materials and Methods: Human non-small cell lung cancer H1299 cells and murine Lewis lung carcinoma LL/2-luc cells were injected into the right hind leg of BALB/c-nude mice and C57BL/6 mice, respectively. Splenectomy or sham operation was performed prior to tumor cell injection or before and after irradiation during tumor growth. Irradiation was delivered with 2–3 fractions of 6 Gy X-ray using a linear accelerator. Flow cytometry analysis was performed for immune cell profiling.Results: Splenectomy prior to tumor injection or at early stage inhibited growth of LL/2-luc tumors but not that of H1299 tumors; however, it did not enhance the antitumor effect of radiation regardless of intervention timing. Flow cytometry analysis showed monocytic myeloid-derived suppressor cells (MDSCs) and activated CD8+ T cells increased after irradiation in the tumors of splenectomized mice, compared to those of sham-operated mice. Administration of anti-PD-1 (programmed death-1) antibodies improved the ability of splenectomy to attenuate the growth of irradiated tumors.Conclusion: Splenectomy has paradoxical effects on radiation-induced tumor growth inhibition, depending on tumor types and intervention timing, but it has an immune-modulating effect when combined with radiation.

Oncologic outcomes after splenectomy during initial cytoreductive surgery in advanced epithelial ovarian cancer: a nationwide population-based cohort study

INTRODUCTION

Epithelial ovarian cancer (EOC) patients undergoing splenectomy during cytoreductive surgery represent a small subgroup of patients. Splenic metastases or technical reasons due to extensive upper abdominal disease may require a splenectomy. It has been hypothesized that as the spleen's antitumor immunologic functions may inhibit cancer growth, splenectomy may promote the growth of residual disease as observed in other cancer types of murine studies. The few studies assessing the impact of splenectomy on the oncologic outcomes of advanced stage EOC patients have reported inconsistent results. It remains unclear whether splenectomy during cytoreductive surgery is justified to achieve complete cytoreduction. The aim of this study was to assess the impact of a splenectomy on perioperative outcomes and survival of advanced stage EOC patients.

MATERIAL AND METHODS

In this nationwide population-based study, all consecutive patients diagnosed with FIGO stage IIIC and IV EOC between 1 January 2008 and 31 December 2015 were identified from the Netherlands Cancer Registry. Patients who underwent cytoreductive surgery combined with platinum-based chemotherapy as primary treatment were selected. Differences in clinicopathologic characteristics between splenectomy and non-splenectomy patients were assessed. Progression-free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier survival curves and log-rank tests. Cox proportional hazards models were used to adjust for covariates that influence survival.

RESULTS

A total of 3911 patients were identified: 99 splenectomy and 3812 non-splenectomy patients. Splenectomy patients were more likely to undergo extensive surgery or surgical reintervention, to receive intraperitoneal chemotherapy, intraoperative and postoperative blood transfusion, to experience postoperative infections, and to be admitted to an intensive care unit (all p < 0.002). No significant differences in PFS or OS were observed between splenectomy versus non-splenectomy patients after adjusting for covariates.

CONCLUSIONS

Although advanced stage EOC patients who undergo splenectomy during cytoreductive surgery have less favorable perioperative outcomes, no adverse impact of splenectomy on the survival of advanced stage EOC patients was observed. Splenectomy during cytoreductive surgery seems to be justified to achieve complete cytoreduction in advanced stage EOC patients.

Changes in peripheral lymphocyte populations in patients with advanced/recurrent ovarian cancer undergoing splenectomy during cytoreductive surgery

BACKGROUND

To investigate changes in peripheral lymphocyte subsets after splenectomy during cytoreductive surgery for advanced or recurrent ovarian cancers.

METHODS

We enrolled 83 patients with advanced or recurrent ovarian cancer who underwent cytoreductive surgery. Twenty patients who also underwent splenectomy were assigned to the splenectomy cohort and the rest were assigned to the non-splenectomy cohort. Flow cytometry was used to measure peripheral lymphocyte subsets consisting of T cells, regulatory T cells, natural killer cells, B cells, and activation antigens before and after surgery.

RESULTS

There was no difference in the number and distribution of peripheral lymphocyte subsets between the two cohorts before surgery. After surgery, we observed elevated levels of T cells (CD3⁺, CD3⁺CD8⁺) in the splenectomy cohort compared to those in the non-splenectomy cohort, and the difference was statistically significant. CD8⁺CD28⁺ T cells had a significant decreasing tendency (P = 0.011) while CD3⁺/HLA-DR⁺ T cells showed the opposite trend (P = 0.001) in the splenectomy cohort. The proportion of Tregs (P = 0.005) and B cells (P < 0.001) including CD3^-/HLA-DR⁺ B cells (P = 0.007) increased after surgery, and the absolute number of T cells and NK cells decreased to different extents (P < 0.001) in the non-splenectomy cohort. The post-operative percentage of CD8⁺CD28⁺ T cells was less than the pre-operative percentage (P = 0.022), which was similar to the splenectomy cohort. There was no significant difference in progression-free survival or overall survival between the groups after a median follow-up time of 41 months.

CONCLUSIONS

The changes in peripheral lymphocyte populations were different between patients with and those without splenectomy during cytoreductive surgery for ovarian cancers. T cells were increased and activated in the splenectomy cohort, whereas, B cells were increased and activated in the non-splenectomy cohort.

Dynamic hematological changes in patients undergoing distal pancreatectomy with or without splenectomy: a population-based cohort study

Background

The clinical outcomes of patients who received distal pancreatectomy with splenectomy (DPS) and spleen-preserving distal pancreatectomy (SPDP) have been generally investigated. However, postoperative hematological changes after distal pancreatectomy with or without splenectomy are poorly understood.

Methods

Information from patients undergoing distal pancreatectomy (DP) between January 2014 and June 2019 at a single institution was reviewed. A linear mixed-effects model was used to compare dynamic hematological changes between different groups.

Results

A total of 302 patients who underwent DP were enrolled. In the long term, most postoperative hematological parameters remained significantly higher than preoperative levels in the DPS group, while postoperative lymphocyte, monocyte, basophil, and platelet levels returned to preoperative levels in the SPDP group. All postoperative hematological parameters except for red blood cell count and serum hemoglobulin level were significantly higher in the DPS group than in the SPDP group. There were no significant differences in hematological changes between the splenic vessel preservation (SVP) and Warshaw technique (WT) groups.

Conclusions

Postoperative hematological changes were significantly different between the DPS and SPDP groups. Compared to DPS, SPDP reduced abnormal hematological changes caused by splenectomy. SVP and WT were comparable in terms of postoperative hematological changes.

Splenic Hematopoietic and Stromal Cells in Cancer Progression

Tumor-derived secretory factors orchestrate splenic hematopoietic and stromal cells to fuel metastasis. The spleen acts as a reservoir site for hematopoietic stem and progenitor cells, which are rapidly exploited as myeloid-derived suppressor cells at the cost of tumor-reactive lymphoid cells. Splenic erythroid progenitor cells and mesenchymal stromal cells contribute directly and indirectly to both tumor immune escape and the metastatic cascade. Animal models provide valuable mechanistic insights, but their translation to a clinical setting highlights specific challenges and open issues. In this review, we envision the exploitation of the spleen as a source for novel biomarkers and therapeutic approaches.

Splenectomy may have more complications than currently proven

The spleen has been one of the least understood major organs for centuries. Its significance is relatively well-known today but it seems that all aspects of its activities are not fully understood. Persian medicine (PM) has special views on the function of spleen; many side effects were reported in PM due to spleen dysfunction. On the other hand nowadays splenectomy as a treatment strategy is recommended for some disorders and increasing risk of infections is considered as the most important long term side effect of that. In this study, we hypothesize that splenectomy may have more side effects than currently proven. According to PM, spleen is in close connection with liver, cardiovascular system, stomach, bone, brain and skin, and that is why any kind of spleen dysfunction leads to change in blood viscosity, appetite and bone strength, liver dysfunction, mood and skin disorders, cancer formation and fever. Considering this viewpoint it can be hypothesized such side effects may also occur after splenectomy. Proven complications of splenectomy include hypercoagulated state, cardiovascular events and infectious diseases but there is also some evidence about increased risk of cancer, skin disease like systemic lupus erythematosus, mood disorder such as depression, defective bone formation and impairment of immunity which can be considered as different levels of evidence to confirm the hypothesis. But for some others such as changes in appetite, there are no studies let alone convincing evidence. Future research about theses possible complications may lead to novel results.

Immune consequences of penfluridol treatment associated with inhibition of glioblastoma tumor growth

Glioblastoma is the most common and lethal brain tumor associated with only 12% median survival rate of patients. Despite the development of advanced surgical, radiation or use of combinations of anti-cancer drugs, treatment for glioblastoma patients is still a challenge. The major contributing factor in glioblastoma progression and resistive nature is its ability to evade the immune surveillance. Hence, modulating the immune system in glioblastoma tumors could be an important strategy for anticancer therapeutics. Penfluridol, an antipsychotic drug has been shown to have anti-cancer properties in our recently published studies. The present study evaluates the immune response of penfluridol in glioblastoma tumors. Our results demonstrated that penfluridol treatment significantly suppressed glioblastoma tumor growth. Our current results demonstrated about 72% suppression of myeloid derived suppressor cells (MDSCs) with penfluridol treatment in mouse bearing U87MG glioblastoma tumors. MDSCs are known to increase regulatory T cells (Treg), which are immunosuppressive in nature and suppresses M1 macrophages that are tumor suppressive in nature. Our results also showed suppression of regulatory T cells as well as elevation of M1 macrophages with penfluridol treatment by 58% and 57% respectively. Decrease in CCL4 as well as IFNγ with penfluridol treatment was also observed indicating decrease in overall tumor inflammation. This is the first report demonstrating immune modulations by penfluridol treatment associated with glioblastoma tumor growth suppression prompting further investigation to establish penfluridol as a treatment option for glioblastoma patients.

Splenectomy suppresses growth and metastasis of hepatocellular carcinoma through decreasing myeloid-derived suppressor cells in vivo

The function of the spleen in tumor development has been investigated for years. The relationship of the spleen with hepatocellular carcinoma (HCC), a huge health burden worldwide, however, remains unknown. The present study aimed to examine the effect of splenectomy on the development of HCC and the possible mechanism. Mouse hepatic carcinoma lines H22 and Hepa1-6 as well as BALB/c and C57 mice were used to establish orthotopic and metastatic mouse models of liver cancer. Mice were divided into four groups, including control group, splenectomy control group (S group), tumor group (T group) and tumor plus splenectomy group (T+S group). Tumor growth, metastases and overall survival were assessed at determined time points. Meanwhile, myeloid-derived suppressor cells (MDSCs) were isolated from the peripheral blood (PB), the spleen and liver tumors, and then measured by flow cytometery. It was found that liver cancer led to splenomegaly, and increased the percentage of MDSCs in the PB and spleen in the mouse models. Splenectomy inhibited the growth and progression of liver cancer and prolonged the overall survival time of orthotopic and metastatic models, which was accompanied by decreased proportion of MDSCs in the PB and tumors of liver cancer-bearing mouse. It was suggested that splenectomy could be considered an adjuvant therapy to treat liver cancer.

Splenectomy inhibits non-small cell lung cancer growth by modulating anti-tumor adaptive and innate immune response

It has been shown that inhibitors of the immune system reside in the spleen and inhibit the endogenous antitumor effects of the immune system. We hypothesized that splenectomy would inhibit the growth of relatively large non-small lung cancer (NSCLC) tumors by modulating the systemic inhibition of the immune system, and in particular Myeloid Derived Suppressor Cells (MDSC). The effect of splenectomy was evaluated in several murine lung cancer models. We found that splenectomy reduces tumor growth and the development of lung metastases, but only in advanced tumors. In immune-deficient NOD-SCID mice the effect of splenectomy on tumor growth and metastatic spread disappeared. Splenectomy significantly reduced the presence of MDSC, and especially monocytic-MDSC in the circulation and inside the tumor. Specific reduction of the CCR2+ subset of monocytic MDSC was demonstrated, and the importance of the CCL2-CCR2 axis was further shown by a marked reduction in CCL2 following splenectomy. These changes were followed by changes in the macrophages contents of the tumors to become more antitumorigenic, and by increased activation of CD8⁺ Cytotoxic T-cells (CTL). By MDSC depletion, and adoptive transfer of MDSCs, we demonstrated that the effect of splenectomy on tumor growth was substantially mediated by MDSC cells. We conclude that the spleen is an important contributor to tumor growth and metastases, and that splenectomy can blunt this effect by depletion of MDSC, changing the amount and characteristics of myeloid cells and enhancing activation of CTL.

Spleen migrating dendritic cells primed with CC531 colon cancer antigen and LPS - is it a method to compromise liver metastases?

The anti-tumor vaccination is burdened by low recruitment rate of intravenously administered in vitro primed DC in liver metastases and lack of supplying them continuously in large numbers. Therefore, it seemed rational to create a model of in vivo vaccination with specifically primed splenic DC and cytotoxic T lymphocytes being continuously supplied to the liver vascular bed. The question we raised was whether anti-tumor immunized splenic DC flowing to liver metastases could adhere to and be cytotoxic to tumor cells. We immunized rats with CC531 tumor cells and stimulated them with Escherichia coli LPS. Subsequently, spleen DC-enriched population was isolated, its activation by LPS, adherence to CC531 cells and cytotoxicity were measured. Spleen cells home to the liver reaching it via splenic vein. These cells can be retrieved by simple washout of liver sinusoids (liver sinusoidal washout cells - LSWC). Their adherence to and cytotoxicity against CC531 cells were evaluated. Moreover, in vitro adherence of splenic DC-enriched cells and LSWC to CC531 liver tumor sections was measured. We found that in vivo immunization of splenic population containing DC, NK cells and lymphocytes with CC531 cells and stimulation with LPS activated these cells but did not significantly increase the cytotoxicity against CC531 cells. There was also no increase in cytotoxicity of LSWC. Adhesion of splenic DC and LWSC to liver CC531 metastases on cryosections was higher than to the adjacent liver tissue. However, it was more expressed on tumor stromal than neoplastic cells. The level of splenic Treg cells down-regulating immune response was found only slightly increased after immunization. Taken together, in the model of in vivo immunization against CC531 cells, low level of spleen DC and spleen-derived LSWC cytotoxicity as well as adherence rate to tumor cells were observed. More effective methods of immunizing splenic DC overcoming the suppressive mechanisms should be looked for.

The flip side of immune surveillance: immune dependency

The growths of many and perhaps all tumors may be stimulated rather than inhibited by a quantitatively low level of immunity. The reason tumors have antigens may be that tumors do not develop in vivo in the absence of at least a minimal immune reaction; in this sense, cancer may be considered an autoimmune disease. This review, based largely on the work of our own laboratory, outlines the data showing that the titration of anti-tumor immunity exhibits the phenomenon of hormesis, i.e. the dose-response curve is non-linear such that low levels of immunity are generally stimulatory but larger quantities of the same immune reactants may inhibit tumor growth. Evidence is also reviewed that suggests that the immune response may vary qualitatively and quantitatively during progression, such that there seems to be, during oncogenesis, a very low level of immune reaction that aids initial tumor growth, followed by a larger reaction that may cause remission of early neoplasms, followed, if the neoplasm survives, by a relative immunologic tolerance to the tumor that may be dependent, at least in part, on suppressor cells. This knowledge may help to explain some clinical observations concerning the relationships among tumor types and the organ distribution of metastases.

Cell mechanics and stress: from molecular details to the ‘universal cell reaction’ and hormesis

The 'universal cell reaction' (UCR), a coordinated biphasic response to external (noxious and other) stimuli observed in all living cells, was described by Nasonov and his colleagues in the mid-20th century. This work has received no attention from cell biologists in the West, but the UCR merits serious consideration. Although it is non-specific, it is likely to be underpinned by precise mechanisms and, if these mechanisms were characterized and their relationship to the UCR elucidated, then our understanding of the integration of cellular function could be improved. As a step towards identifying such mechanisms, I review some recent advances in understanding cell mechanics and the stress response and I suggest potentially testable hypotheses. There is a particular need for time-course studies of cellular responses to different stimulus doses or intensities. I also suggest a correspondence with hormesis; re-investigation of the UCR using modern biophysical and molecular-biological techniques might throw light on this much-discussed phenomenon.