The causal relationship between gut microbiota and lymphoma: a two-sample Mendelian randomization study

Background

Previous studies have indicated a potential link between the gut microbiota and lymphoma. However, the exact causal interplay between the two remains an area of ambiguity.

Methods

We performed a two-sample Mendelian randomization (MR) analysis to elucidate the causal relationship between gut microbiota and five types of lymphoma. The research drew upon microbiome data from a research project of 14,306 participants and lymphoma data encompassing 324,650 cases. Single-nucleotide polymorphisms were meticulously chosen as instrumental variables according to multiple stringent criteria. Five MR methodologies, including the inverse variance weighted approach, were utilized to assess the direct causal impact between the microbial exposures and lymphoma outcomes. Moreover, sensitivity analyses were carried out to robustly scrutinize and validate the potential presence of heterogeneity and pleiotropy, thereby ensuring the reliability and accuracy.

Results

We discerned 38 potential causal associations linking genetic predispositions within the gut microbiome to the development of lymphoma. A few of the more significant results are as follows: Genus Coprobacter (OR = 0.619, 95% CI 0.438-0.873, P = 0.006) demonstrated a potentially protective effect against Hodgkin's lymphoma (HL). Genus Alistipes (OR = 0.473, 95% CI 0.278-0.807, P = 0.006) was a protective factor for diffuse large B-cell lymphoma. Genus Ruminococcaceae (OR = 0.541, 95% CI 0.341-0.857, P = 0.009) exhibited suggestive protective effects against follicular lymphoma. Genus LachnospiraceaeUCG001 (OR = 0.354, 95% CI 0.198-0.631, P = 0.0004) showed protective properties against T/NK cell lymphoma. The Q test indicated an absence of heterogeneity, and the MR-Egger test did not show significant horizontal polytropy. Furthermore, the leave-one-out analysis failed to identify any SNP that exerted a substantial influence on the overall results.

Conclusion

Our study elucidates a definitive causal link between gut microbiota and lymphoma development, pinpointing specific microbial taxa with potential causative roles in lymphomagenesis, as well as identifying probiotic candidates that may impact disease progression, which provide new ideas for possible therapeutic approaches to lymphoma and clues to the pathogenesis of lymphoma.

Assessing the causal association between dietary vitamin intake and lymphoma risk: a Mendelian randomisation study

Observational studies of diet-related vitamins and lymphoma risk results were inconsistent. Our study aimed to estimate the causality between dietary vitamin intake and lymphoma through a Mendelian randomisation (MR) study. We enrolled dietary-related retinol, vitamin C, vitamin E, vitamin B6 and vitamin B12 as exposures of interest, with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) as the outcome. The causal effects were estimated using inverse variance weighting (IVW), MR-Egger regression analysis and weighted median, supplemented by sensitivity analyses. The results revealed that genetically predicted dietary vitamin B12 intake was associated with a reduced HL risk (OR = 0.22, 95% CI 0.05-0.91, p = 0.036). The Q test did not reveal heterogeneity, the MR-Egger test showed no significant intercepts, and the leave-one-out (LOO) analysis did not discover any SNP that affect the results. No causal relationship about dietary vitamin intake on the NHL risk was observed.

Human Immunodeficiency Virus Related Non-Hodgkin's Lymphoma

Human immunodeficiency virus infection is related with an increased risk of hematological malignancy principally, non-Hodgkin lymphoma. Most non-Hodgkin lymphomas are acquired immunodeficiency syndrome defining and constitute greater than 50% of all acquired immunodeficiency syndrome defining cancers. The main pathogenesis mechanisms are immunodeficiency, chronic antigenic stimulation, and the ability to infect cancer cells causing direct carcinogenesis. Human immunodeficiency virus related non-Hodgkin lymphomas are heterogeneous in immunophenotyping and molecular features; and choice of drug treatments is similar with sporadic types. The main objective is to assess the epidemiology, pathogenesis, and morphology of human immunodeficiency virus related non-Hodgkin lymphoma. The searching strategy was done by searching relevant original and review articles from www.biosemanticjane/org, Google scholar, Google, and PubMed sites using keywords like; Acquired immunodeficiency syndrome, Human immunodeficiency virus, and non-Hodgkin lymphoma. In conclusion, human immunodeficiency virus infected people continue to have elevated risk of non-Hodgkin lymphoma. Diffuse large B-cell lymphomas are the most common and severe subtype. The pathogenesis of this type of lymphoma is associated with chromosomal abnormalities that deregulate the expression of various oncogenes by different viral particles and cytokines. However, the role of these viral particles and cytokines on pathogenesis is not clearly stated, so further study could be required.

Spectrum of imaging findings in AIDS-related diffuse large B cell lymphoma

Lymphoma in HIV-infected patients is AIDS defining. This is the second most common AIDS defining malignancy after Kaposi's sarcoma. Development of lymphoma in HIV patients is related to immunosuppression and high viral load. Co-infection with other lymphotrophic viruses especially EBV is also strongly associated with development of lymphoma in HIV patients. Despite advances in HAART therapy, incidence of diffuse large B cell lymphoma in HIV-infected patients remains significantly higher than in the general population.Early diagnosis is challenging due to presence of opportunistic infections and atypical presentation of the lymphoma in this subset of patients. Atypical imaging findings are not unusual, and the diagnosis of lymphoma on imaging is on many occasions unexpected as the patient would ideally be initially investigated for presumed opportunistic infection.Lymphoma treatment approaches in HIV patients are complicated by comorbidity with opportunistic infections and performance status of the patients. Treatment failure and early relapse are also common in AIDS-related lymphoma. This review article highlights the common and unusual multimodality imaging findings in HIV-associated lymphoma.

HIV-related Malignancies and Mimics: Imaging Findings and Management

The risk of developing malignancy is higher in patients with human immunodeficiency virus (HIV) infection than in non-HIV-infected patients. Several factors including immunosuppression, viral coinfection, and high-risk lifestyle choices lead to higher rates of cancer in the HIV-infected population. A subset of HIV-related malignancies are considered to be acquired immunodeficiency syndrome (AIDS)-defining malignancies, as their presence confirms the diagnosis of AIDS in an HIV-infected patient. The introduction of highly active antiretroviral therapy (HAART) has led to a significant drop in the rate of AIDS-defining malignancies, including Kaposi sarcoma, non-Hodgkin lymphoma, and invasive cervical carcinoma. However, non-AIDS-defining malignancies (eg, Hodgkin lymphoma, lung cancer, hepatocellular carcinoma, and head and neck cancers) now account for an increasing number of cancer cases diagnosed in HIV-infected patients. Although the number has decreased, AIDS-defining malignancies account for 15%-19% of all deaths in HIV-infected patients in the post-HAART era. Most HIV-related malignancies in HIV-infected patients manifest at an earlier age with a more aggressive course than that of non-HIV-related malignancies. Understanding common HIV-related malignancies and their specific imaging features is crucial for making an accurate and early diagnosis, which impacts management. Owing to the weakened immune system of HIV-infected patients, other entities such as various infections, particularly opportunistic infections, are prevalent in these patients. These processes can have confounding clinical and imaging manifestations that mimic malignancy. This article reviews the most common AIDS-defining and non-AIDS-defining malignancies, the role of imaging in their diagnosis, and the imaging mimics of malignancies in HIV-infected patients. ^©RSNA, 2018.

Primary mediastinal large B cell lymphoma in a woman who is human immunodeficiency virus positive presenting with superior vena cava syndrome: a case report

Background

The risk of non-Hodgkin lymphoma is increased 200-fold in individuals seropositive for human immunodeficiency virus compared to those free from human immunodeficiency virus. Human immunodeficiency virus-associated non-Hodgkin lymphoma is known for its atypical presentation, aggressive ability, widespread involvement, poor response to chemotherapy, and high relapse potential which makes both the diagnosis and management a difficult undertaking especially in resource-poor settings.

Case presentation

We report a case of primary mediastinal large B cell lymphoma in a 46-year-old woman of African descent who is human immunodeficiency virus positive who presented with symptoms of superior vena cava syndrome. Her past medical history was remarkable for a 23-year history of systemic hypertension and a 10-year history of human immunodeficiency virus infection. A physical examination revealed an underweight woman with right-sided facial, neck, upper limb, and trunk swelling together with distended veins on her chest and abdomen draining downwards. A respiratory examination revealed a reduced chest expansion, stony dull percussion note, and absent breath sounds on her entire right side with a left-sided tracheal deviation. She had a CD4 count of 146 cells/μL. A chest X-ray revealed a homogenous opacification on her right side with a left-sided tracheal deviation while a computed tomography scan of her chest revealed a solid mass on her right side. An echocardiogram showed a huge well-circumscribed mass (4.6×3.3 cm) with spontaneous echocardiographic contrast compressing her heart inferiorly. She had severe pulmonary hypertension (right ventricular systolic pressure 58 mmHg) but preserved left ventricular systolic function, no thrombus was seen, and her pericardium was normal. A computed tomography angiography of her aorta ruled out an aortic aneurysm. Finally, she underwent mediastinoscopy and a direct biopsy of the mass was taken for histopathology. Hematoxylin and eosin staining demonstrated a dense lymphoid infiltrate of large malignant cells with pleomorphic nuclei in clusters, compartmentalized by fine bands of fibrosis, and frequent mitoses were present. A diagnosis of mediastinal large B cell lymphoma was reached.

Conclusions

The presence of a mediastinal widening coupled with a history of unintentional yet significant weight loss in an individual who is human immunodeficiency virus seropositive should raise an index of suspicion for lymphomas and warrant aggressive investigations and timely management.

Etiological study of lymphadenopathy in HIV-infected patients in a tertiary care hospital

INTRODUCTION

Human immunodeficiency virus (HIV) infection has become a global pandemic. Persistent generalized lymphadenopathy (PGL) is very common manifestation of HIV infection. Moreover, different opportunistic infections such as tuberculosis (TB) and malignancies may present with lymphadenopathy. Mycobacterium avium complex (MAC) infection is most common with cluster of differentiation (CD)4+ count ≤50 cells/μL. Fine-needle aspiration cytology (FNAC) offers a simple and effective modality for obtaining a representative sample of the material from lymph nodes, permitting cytological evaluation and other investigations.

AIMS AND OBJECTIVES

The aim of this study is to find out the different etiologies of lymphadenopathy in HIV-infected patients and to establish a possible correlation with CD4+ count.

MATERIALS AND METHODS

A total of 100 HIV-infected patients having significant (>1 cm) extrainguinal lymphadenopathy were studied in 1 year at the Department of Pathology by FNAC and the stains used were Leishman-Giemsa, Ziehl-Neelsen (ZN), Papanicoloau, and Gram stains. For tubercular culture, Löwenstein-Jensen (LJ) medium was used. CD4+count was done by flow cytometer.

RESULT

The present study revealed four types of cytomorphological variants in lymphadenopathy cases by FNAC, which include: Reactive hyperplasia and caseation necrosis; caseation necrosis and ill-formed granuloma; well-formed granuloma without any necrosis; and non-Hodgkin lymphoma (NHL). The highest acid-fast bacilli (AFB) positivity was among the patients showing caseation necrosis. Tubercular culture in LJ media turned out as a more sensitive method for diagnosis than routine ZN staining. The 2 cases that showed well-formed epithelioid granuloma without any necrosis turned out to be histoplasmosis and cryptococcosis, respectively. In this study, we found 2 cases of NHL. The study also revealed that caseation necrosis and AFB positivity along with opportunistic infections increases with decreased CD4+ count.