Mathematical modeling suggests heterogeneous replication of Mycobacterium tuberculosis in rabbits

Tuberculosis (TB), the disease caused by Mycobacterium tuberculosis (Mtb), remains a major health problem with 10.6 million cases of the disease and 1.6 million deaths in 2021. It is well understood that pulmonary TB is due to replication of Mtb in the lung but quantitative details of Mtb replication and death in lungs of patients and how these rates are related to the degree of lung pathology are unknown. We performed experiments with rabbits infected with a novel, virulent clinical Mtb isolate of the Beijing lineage, HN878, carrying an unstable plasmid pBP10. In our in vitro experiments we found that pBP10 is more stable in HN878 strain than in a more commonly used laboratory-adapted Mtb strain H37Rv (the segregation coefficient being s = 0 . 10 in HN878 vs. s = 0 . 18 in H37Rv). Interestingly, the kinetics of plasmid-bearing bacteria in lungs of Mtb-infected rabbits did not follow an expected monotonic decline; the percent of plasmid-bearing cells increased between 28 and 56 days post-infection and remained stable between 84 and 112 days post-infection despite a large increase in bacterial numbers in the lung at late time points. Mathematical modeling suggested that such a non-monotonic change in the percent of plasmid-bearing cells can be explained if the lung Mtb population consists of several (at least 2) sub-populations with different replication/death kinetics: one major population expanding early and being controlled/eliminated, while another, a smaller population expanding at later times causing a counterintuitive increase in the percent of plasmid-bearing cells. Given that HN878 forms well circumscribed granulomas in rabbits, our results suggest independent bacterial dynamics in subsets of such granulomas. Our model predictions can be tested in future experiments in which HN878-pBP10 dynamics in individual granulomas is followed over time.

Immune mapping of human tuberculosis and sarcoidosis lung granulomas

Tuberculosis (TB) and sarcoidosis are both granulomatous diseases. Here, we compared the immunological microenvironments of granulomas from TB and sarcoidosis patients using in situ sequencing (ISS) transcriptomic analysis and multiplexed immunolabeling of tissue sections. TB lesions consisted of large necrotic and cellular granulomas, whereas "multifocal" granulomas with macrophages or epitheloid cell core and a T-cell rim were observed in sarcoidosis samples. The necrotic core in TB lesions was surrounded by macrophages and encircled by a dense T-cell layer. Within the T-cell layer, compact B-cell aggregates were observed in most TB samples. These B-cell clusters were vascularized and could contain defined B-/T-cell and macrophage-rich areas. The ISS of 40-60 immune transcripts revealed the enriched expression of transcripts involved in homing or migration to lymph nodes, which formed networks at single-cell distances in lymphoid areas of the TB lesions. Instead, myeloid-annotated regions were enriched in CD68, CD14, ITGAM, ITGAX, and CD4 mRNA. CXCL8 and IL1B mRNA were observed in granulocytic areas in which M. tuberculosis was also detected. In line with ISS data indicating tertiary lymphoid structures, immune labeling of TB sections expressed markers of high endothelial venules, follicular dendritic cells, follicular helper T cells, and lymph-node homing receptors on T cells. Neither ISS nor immunolabeling showed evidence of tertiary lymphoid aggregates in sarcoidosis samples. Together, our finding suggests that despite their heterogeneity, the formation of tertiary immune structures is a common feature in granulomas from TB patients.

De Novo Granuloma of the Membranous Vocal Fold: A Marker of Occult Malignancy

OBJECTIVE

De novo occurrence of granuloma (granulation tissue) on the membranous vocal fold is not readily explained by usual causes of granuloma at the vocal process. We describe a series of patients.

STUDY DESIGN

Case series.

SETTING

Single academic institution.

METHODS

Cases were identified over a 16-year period. All patients exhibited granulation tissue on pathology. Demographic details, presentation, treatment, histology, and clinical outcomes were recorded.

RESULTS

Five patients (mean age: 74.0 ± 6.1 years, 40.0% male, 40.0% former smokers) underwent a biopsy. Persistent or recurrent granulation led to a second biopsy in 4 patients an average of 1423.5 days later, revealing a new diagnosis of squamous cell carcinoma (SCC) in situ in one and mild dysplasia in another. Further persistence or recurrence led to a third biopsy or excision an average of 302.3 days later in 3 patients, demonstrating SCC in situ in 1. An average of 2.5 biopsies were required with a mean time to SCC in situ diagnosis of 919.5 days from presentation. Two patients continued to demonstrate persistent granulation tissue on histology.

CONCLUSION

The membranous vocal fold is an atypical location for granuloma and portends a risk of occult malignancy. The occurrence of de novo granuloma at this site should prompt close long-term clinical surveillance with a low threshold for biopsy. Consideration should be given to tissue collection in the operating room to adequately sample the lesion's base. Concern should persist even after a negative biopsy, and serial observation with repeat biopsy as needed should be pursued.

Chemokine expression profile of an innate granuloma

Granulomas are defined by the presence of organized layers of immune cells that include macrophages. Granulomas are often characterized as a way for the immune system to contain an infection and prevent its dissemination. We recently established a mouse infection model where Chromobacterium violaceum induces the innate immune system to form granulomas in the liver. This response successfully eradicates the bacteria and returns the liver to homeostasis. Here, we sought to characterize the chemokines involved in directing immune cells to form the distinct layers of a granuloma. We use spatial transcriptomics to investigate the spatial and temporal expression of all CC and CXC chemokines and their receptors within this granuloma response. The expression profiles change dynamically over space and time as the granuloma matures and then resolves. To investigate the importance of monocyte-derived macrophages in this immune response, we studied the role of CCR2 during C. violaceum infection. Ccr2-/- mice had negligible numbers of macrophages, but large numbers of neutrophils, in the C. violaceum-infected lesions. In addition, lesions had abnormal architecture resulting in loss of bacterial containment. Without CCR2, bacteria disseminated and the mice succumbed to the infection. This indicates that macrophages are critical to form a successful innate granuloma in response to C. violaceum.

Adjuvants influence the immune cell populations present at the injection site granuloma induced by whole-cell inactivated paratuberculosis vaccines in sheep

Vaccination is the most effective tool for paratuberculosis control. Currently, available vaccines prevent the progression of clinical disease in most animals but do not fully protect them against infection and induce the formation of an injection site granuloma. The precise mechanisms that operate in response to vaccination and granuloma development, as well as the effect that adjuvants could trigger, have not been fully investigated. Therefore, this study aimed to investigate the injection site granulomas induced by two inactivated paratuberculosis vaccines, which differ in the adjuvant employed. Two groups of 45-day-old lambs were immunized with two commercially available vaccines-one (n = 4) with Gudair® and the other (n = 4) with Silirum®. A third group (n = 4) was not vaccinated and served as control. The peripheral humoral response was assessed throughout the study by a commercial anti-Mycobacterium avium subspecies paratuberculosis (Map) antibody indirect ELISA, and the cellular immune response was assessed similarly by the IFN-γ release and comparative intradermal tests. The injection site granulomas were measured during the experiment and sampled at 75 days post-vaccination (dpv) when the animals were euthanized. The tissue damage, antigen and adjuvant distribution, and the presence and amount of immune cells were then determined and assessed by immunohistochemical methods. Antibodies against Map antigens; a general macrophage marker (Iba1), M1 (iNOS), and M2 (CD204) macrophages; T (CD3), B (CD20), and γδ T lymphocytes, proteins MHC-II and NRAMP1, and cytokines IL-4, IL-10, TNF, and IFN-γ were employed. Silirum® elicited a stronger peripheral cellular immune response than Gudair®, while the latter induced larger granulomas and more tissue damage at the site of injection. Additionally, adjuvant and Map antigen distribution throughout the granulomatous inflammatory infiltrate, as well as the NRAMP1 cell expression, which is linked to antigen phagocytosis, were highly irregular. In Silirum® induced granulomas, a higher number of MHC-II and TNF-expressing cells and a lower number of M2 macrophages suggested an improved antigen presentation, which could be due to the better antigen distribution and reduced tissue damage induced by this vaccine.

Prediction of Tuberculosis From Lung Tissue Images of Diversity Outbred Mice Using Jump Knowledge Based Cell Graph Neural Network

Tuberculosis (TB), primarily affecting the lungs, is caused by the bacterium Mycobacterium tuberculosis and poses a significant health risk. Detecting acid-fast bacilli (AFB) in stained samples is critical for TB diagnosis. Whole Slide (WS) Imaging allows for digitally examining these stained samples. However, current deep-learning approaches to analyzing large-sized whole slide images (WSIs) often employ patch-wise analysis, potentially missing the complex spatial patterns observed in the granuloma essential for accurate TB classification. To address this limitation, we propose an approach that models cell characteristics and interactions as a graph, capturing both cell-level information and the overall tissue micro-architecture. This method differs from the strategies in related cell graph-based works that rely on edge thresholds based on sparsity/density in cell graph construction, emphasizing a biologically informed threshold determination instead. We introduce a cell graph-based jumping knowledge neural network (CG-JKNN) that operates on the cell graphs where the edge thresholds are selected based on the length of the mycobacteria's cords and the activated macrophage nucleus's size to reflect the actual biological interactions observed in the tissue. The primary process involves training a Convolutional Neural Network (CNN) to segment AFBs and macrophage nuclei, followed by converting large (42831*41159 pixels) lung histology images into cell graphs where an activated macrophage nucleus/AFB represents each node within the graph and their interactions are denoted as edges. To enhance the interpretability of our model, we employ Integrated Gradients and Shapely Additive Explanations (SHAP). Our analysis incorporated a combination of 33 graph metrics and 20 cell morphology features. In terms of traditional machine learning models, Extreme Gradient Boosting (XGBoost) was the best performer, achieving an F1 score of 0.9813 and an Area under the Precision-Recall Curve (AUPRC) of 0.9848 on the test set. Among graph-based models, our CG-JKNN was the top performer, attaining an F1 score of 0.9549 and an AUPRC of 0.9846 on the held-out test set. The integration of graph-based and morphological features proved highly effective, with CG-JKNN and XGBoost showing promising results in classifying instances into AFB and activated macrophage nucleus. The features identified as significant by our models closely align with the criteria used by pathologists in practice, highlighting the clinical applicability of our approach. Future work will explore knowledge distillation techniques and graph-level classification into distinct TB progression categories.

Treatment of Granulomatous Inflammation in Pulmonary Sarcoidosis

The management of pulmonary sarcoidosis is a complex interplay of disease characteristics, the impact of medications, and patient preferences. Foremost, it is important to weigh the risk of anti-granulomatous treatment with the benefits of lung preservation and improvement in quality of life. Because of its high spontaneous resolution rate, pulmonary sarcoidosis should only be treated in cases of significant symptoms due to granulomatous inflammation, lung function decline, or substantial inflammation on imaging that can lead to irreversible fibrosis. The longstanding basis of treatment has historically been corticosteroid therapy for the control of granulomatous inflammation. However, several corticosteroid-sparing options have increasing evidence for use in refractory disease, inability to taper steroids to an acceptable dose, or in those with toxicity to corticosteroids. Treatment of sarcoidosis should be individualized for each patient due to the heterogeneity of the clinical course, comorbid conditions, response to therapy, and tolerance of medication side effects.

Neutrophil extracellular traps (NETs) and Th-2 dominant immune responses in chronic granulomatous chromobalstomycosis

Chromoblastomycosis (CBM), a chronic, granulomatous, suppurative mycosis of the skin and subcutaneous tissue, is caused by several dematiaceous fungi. The formation of granulomas, tissue proliferation, and fibrosis in response to these pathogenic fungi is believed to be intricately linked to host immunity. To understand this complex interaction, we conducted a comprehensive analysis of immune cell infiltrates, neutrophil extracellular traps (NETs) formation, and the fibrosis mechanism in 20 CBM lesion biopsies using immunohistochemical and immunofluorescence staining methods. The results revealed a significant infiltration of mixed inflammatory cells in CBM granulomas, prominently featuring a substantial presence of Th2 cells and M2 macrophages. These cells appeared to contribute to the production of collagen I and III in the late fibrosis mechanism, as well as NETs formation. The abundance of Th2 cytokines may act as a factor promoting the bias of macrophage differentiation toward M2, which hinders efficient fungal clearance while accelerates the proliferation of fibrous tissue. Furthermore, the expression of IL-17 was noted to recruit neutrophils, facilitating subsequent NETs formation within CBM granulomas to impede the spread of sclerotic cells. Understanding of these immune mechanisms holds promise for identifying therapeutic targets for managing chronic granulomatous CBM.

Tattoo-Associated Skin Reaction in a Melanoma Patient Receiving B-RAF and MEK Inhibitors: A Case Report with an Emphasis on Etiopathogenic and Histological Features

Tattoo-associated cutaneous reactions have become quite frequent given the increasing percentage of tattooed subjects globally and also in Italy. On the other hand, the increasing use of target therapy is showing the ability of these drugs to affect the immune system and also cause adverse tattoo-related reactions. In this paper, we report a case of a 42-year-old patient with stage-IIID melanoma undergoing treatment with Dabrafenib and Trametinib. The patient reported erythema, oedema and scaling in areas of the body containing a black tattoo, and, conversely, no signs and/or symptoms in areas with tattoos of a different color. Histopathological and immunohistochemical features indicated a lympho-histiocytic reaction with a granulomatous morphology, mainly distributed around the vessels and hair adnexa. By discussing the cases reported in the literature prior to ours, we concluded and provided the possible indications of the pathogenesis.

Automated quantitative assay of fibrosis characteristics in tuberculosis granulomas

Introduction

Granulomas, the pathological hallmark of Mycobacterium tuberculosis (Mtb) infection, are formed by different cell populations. Across various stages of tuberculosis conditions, most granulomas are classical caseous granulomas. They are composed of a necrotic center surrounded by multilayers of histocytes, with the outermost layer encircled by fibrosis. Although fibrosis characterizes the architecture of granulomas, little is known about the detailed parameters of fibrosis during this process.

Methods

In this study, samples were collected from patients with tuberculosis (spanning 16 organ types), and Mtb-infected marmosets and fibrotic collagen were characterized by second harmonic generation (SHG)/two-photon excited fluorescence (TPEF) microscopy using a stain-free, fully automated analysis program.

Results

Histopathological examination revealed that most granulomas share common features, including necrosis, solitary and compact structure, and especially the presence of multinuclear giant cells. Masson's trichrome staining showed that different granuloma types have varying degrees of fibrosis. SHG imaging uncovered a higher proportion (4%~13%) of aggregated collagens than of disseminated type collagens (2%~5%) in granulomas from matched tissues. Furthermore, most of the aggregated collagen presented as short and thick clusters (200~620 µm), unlike the long and thick (200~300 µm) disseminated collagens within the matched tissues. Matrix metalloproteinase-9, which is involved in fibrosis and granuloma formation, was strongly expressed in the granulomas in different tissues.

Discussion

Our data illustrated that different tuberculosis granulomas have some degree of fibrosis in which collagen strings are short and thick. Moreover, this study revealed that the SHG imaging program could contribute to uncovering the fibrosis characteristics of tuberculosis granulomas.

Practices and Attitudes of Surgeons With Regard to Spilled Gallstones During Laparoscopic Cholecystectomy: A Cross-Sectional Study From Saudi Arabia

BACKGROUND

Gallbladder perforation and gallstone leakage are frequent complications following laparoscopic cholecystectomy (LC). Failure to remove gallstones may result in several issues that manifest immediately or years later. The goal of this study was to evaluate the attitudes of surgeons and the procedures used by them to deal with gallstone spillage during LC.

METHODS

A cross-sectional design was followed. Surgeons in nine healthcare facilities in the Qassim region of Saudi Arabia were approached through non-probability convivence sampling and the survey was distributed in each of the general surgery divisions. The study included general surgeons who currently performed LC and incomplete responses and interns were excluded. A self-administered questionnaire was developed with 18 questions regarding demographics, center, and designation at the hospital, surgeons' experience of LC, and exposure to gallstone spillage. Furthermore, items regarding knowledge, attitude, and self-reported practices related to gallstone spillage such as incidence, complications, and intervention taken to prevent gallstone spillage were also included. The level of significance was set at P <0.05.

RESULTS

There were 82 participants of both genders, including consultants, specialists, and residents. While only 23 (28%) participants had actually observed patients with complications from spilled stones, 46 (56.1%) participants were aware of this possibility, 53 (64.6%) deemed it inappropriate to bring up gallstone spillage when securing consent for LC, and 67 (81.7%) believed that such an incident needed to be documented in the operation notes. Only 11 (13.4%) thought that the complications arising out of the unretrieved gallstones should fall under the legal purview of the operative surgeon. There were very few complications of spilled gallstones that the participants were aware of, and none of them anticipated problems to arise more than three years after LC.

CONCLUSIONS

Awareness of the risks associated with gallstone spillage during LC needs to be raised, and it is imperative to standardize the practices related to their management.

Diagnosis of systemic sarcoidosis in a patient with bilateral granulomatous pan-uveitis: a case report

Introduction and importance

Sarcoidosis is a systemic disease usually presenting with features of hilar lymphadenopathy like persistent cough, dyspnoea, cough, night sweats. However, its first and only manifestation can be ocular symptoms consistent with uveitis.

Case presentation

The authors present such association in a 53-year-old female who had ocular symptoms on and off, designated as uveitis. Despite medications, her symptoms rather flared up. On diagnostic assesement done years later, chest X-ray showed bilateral hilar lymphadenopathy, serum angiotensin-converting enzyme levels were also raised, and the diagnosis of systemic sarcoidosis was confirmed.

Clinical discussion

Eye involvement can occur way before the systemic presence of the disease is detected and can be present clinically as an isolated entity which makes diagnosis of underlying sarcoidosis a challenge.

Conclusion

Consideringsarcoidosis as one of the differential diagnosis when attending patients with non-resolving uveitis remains the mainstay of this report.

Intracranial granuloma in a patient with granulomatosis with polyangiitis under rituximab maintenance: A case report

BACKGROUND

Rituximab (RTX) is being used for both induction and maintenance of anti-neutrophil cytoplasmic antibody (ANCA) -associated vasculitis. However, the efficacy of RTX for the granulomatous findings of granulomatosis with polyangiitis (GPA) has not been demonstrated as clearly as its vasculitic manifestations.

CASE SUMMARY

A 46-year-old man was diagnosed in 2019 with GPA with constitutional symptoms, bilateral mastoiditis, prostatic necrosis, nodules in both lungs, pauci-immune necrotizing glomerulonephritis and high level of PR3-ANCA. He reached clinical remission after induction with high-dose corticosteroids and intravenous cyclophosphamide pulses at the 3rd month. Two months following the second cycle of RTX as maintenance, he developed multiple cranial mass lesions, and excisional biopsy revealed necrotizing vasculitis with granuloma formation. Remission was achieved with long-term high-dose corticosteroid therapy after surgical excision.

CONCLUSION

We observed a relapse of GPA with intracranial granulomatous lesions in a patient under RTX maintenance. Limited efficacy of RTX should be considered for mainly granulomatous manifestations in patients with GPA.

Advances in cellular and tissue-based imaging techniques for sarcoid granulomas

Sarcoidosis embodies a complex inflammatory disorder spanning multiple systems, with its origin remaining elusive. It manifests as the infiltration of inflammatory cells that coalesce into distinctive noncaseous granulomas within afflicted organs. Unraveling this disease necessitates the utilization of cellular or tissue-based imaging methods to both visualize and characterize the biochemistry of these sarcoid granulomas. Although hematoxylin and eosin stain, standard in routine use alongside cytological stains have found utility in diagnosis within clinical contexts, special stains such as Masson's trichrome, reticulin, methenamine silver, and Ziehl-Neelsen provide additional varied perspectives of sarcoid granuloma imaging. Immunohistochemistry aids in pinpointing specific proteins and gene expressions further characterizing these granulomas. Finally, recent advances in spatial transcriptomics promise to divulge profound insights into their spatial orientation and three-dimensional (3-D) molecular mapping. This review focuses on a range of preexisting imaging methods employed for visualizing sarcoid granulomas at the cellular level while also exploring the potential of the latest cutting-edge approaches like spatial transcriptomics and matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), with the overarching goal of shedding light on the trajectory of sarcoidosis research.

Granuloma, vasculitis, and demyelination in sarcoid neuropathy

BACKGROUND

Despite the suggestion that direct compression by granuloma and ischemia resulting from vasculitis can cause nerve fiber damage, the mechanisms underlying sarcoid neuropathy have not yet been fully clarified.

METHODS

We examined the clinicopathological features of sarcoid neuropathy by focusing on electrophysiological and histopathological findings of sural nerve biopsy specimens. We included 18 patients with sarcoid neuropathy who had non-caseating epithelioid cell granuloma in their sural nerve biopsy specimens.

RESULTS

Although electrophysiological findings suggestive of axonal neuropathy were observed, particularly in the lower limbs, all but three patients showed ≥1 abnormalities in nerve conduction velocity or distal motor latency. Additionally, a conduction block was observed in 11 of the 16 patients for whom waveforms were assessed; five of them fulfilled motor nerve conduction criteria strongly supportive of demyelination as defined in the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guideline for chronic inflammatory demyelinating polyneuropathy (CIDP). In most patients, sural nerve biopsy specimens revealed a mild to moderate degree of myelinated fiber loss. Fibrinoid necrosis was observed in one patient, and electron microscopy analysis revealed demyelinated axons close to granulomas in six patients.

CONCLUSIONS

Patients with sarcoid neuropathy may meet the EAN/PNS electrophysiological criteria for CIDP due to the frequent presence of conduction blocks. Based on our results, in addition to the ischemic damage resulting from granulomatous inflammation, demyelination may play an important role in the mechanism underlying sarcoid neuropathy.

Utility of bone marrow examination (BME) in the diagnosis of pyrexia of unknown origin (PUO)

INTRODUCTION

Bone marrow examination (BME) is a useful tool in the diagnosis of haematological and non-haematological diseases. It plays an important role in early diagnosis of the underlying cause of pyrexia of unknown origin (PUO) and can influence the management of patients. Bone marrow aspiration (BMA) plays a very important role in establishing a definitive diagnosis in cases of PUO. The aim of this study was to review the indications and usefulness of bone marrow aspirates sent for microbiological evaluation as a diagnostic tool with histopathological correlation.

METHODOLOGY

A prospective study was conducted from 1 January 2017 to 30 September 2019 in the Department of Microbiology and Pathology on the bone marrow aspirates of patients of all groups.

RESULTS

A total of 148 bone marrow aspirates were included. The cases were categorized as classical PUO (n = 81/148, 54.7%), nosocomial PUO (n = 4 /148, 2.7%), neutropenic PUO (n = 18/148, 12.1%), and immunocompromised PUO (n = 45/148, 30.4%), among which were systemic lupus erythematosus cases n = 8/45 (22.2%), human immunodeficiency virus positive cases n = 10/45 (17.7%), and renal transplant cases n = 27/45 (60%). A total of 28 BMAs were positive for microorganisms, out of which bacterial pathogens were n = 12 (42.8%), mycobacterial n = 12, 42.8%, fungal (n = 3, 10.7 %), and viruses (n = 1, 3.5%).

CONCLUSIONS

This study helped in highlighting the role of bone marrow examination as an important diagnostic method in the diagnosis of infectious diseases.

A Structural Analysis of Host-Parasite Interactions in Achatina fulica (Giant African Snail) Infected with Angiostrongylus cantonensis

Angiostrongylus cantonensis is a nematode parasite that resides in the pulmonary arteries of rodents, serving as its definitive hosts. The life cycle involves several species of non-marine gastropods as intermediate hosts, and the African giant snail Achatina fulica is considered one of the most important around the world. Experimental data concerning A. cantonensis infection in the African giant snail remains notably limited. This helminth causes eosinophilic meningitis or meningoencephalitis in humans, representing an emergent zoonosis in Brazil. Understanding the host-parasite relationship through the application of new tools is crucial, given the complex interaction between zoonosis and the intricate mechanisms involving wild/human hosts, parasite adaptation, and dispersion. The objective of this study was to employ SEM as a novel methodology to understand the structural organization of the host tissue, particularly the granuloma formation. This sheds light on the complex balance between A. fulica and A. cantonensis. Nine three-month-old snails were randomly selected and exposed for 24 h to a concentration of 2000 L1/dose of A. cantonensis. A necropsy was performed 37 days after the infection, and the samples were examined using light and scanning electron microscopy (SEM). The histopathological results revealed third-stage larvae of A. cantonensis associated with granulomas distributed throughout the head-foot mass, mantle, and kidney. Scanning electron microscopy of the histological section surface showed that the granuloma is surrounded by a cluster of spherical particles, which are distributed in the region bordering the larvae. This reveal details of the nematode structure, demonstrating how this methodology can enhance our understanding of the role of granulomas in molluscan tissue. The structural characteristics of granuloma formation in A. fulica suggest it as an excellent invertebrate host for A. cantonensis. This relationship appears to provide protection to the parasite against the host's immune defense system while isolating the snail's tissue from potential exposure to nematode antigens.

The Roles of Various Immune Cell Populations in Immune Response against Helminths

Helminths are multicellular parasites that are a substantial problem for both human and veterinary medicine. According to estimates, 1.5 billion people suffer from their infection, resulting in decreased life quality and burdens for healthcare systems. On the other hand, these infections may alleviate autoimmune diseases and allergy symptoms. The immune system is programmed to combat infections; nevertheless, its effector mechanisms may result in immunopathologies and exacerbate clinical symptoms. This review summarizes the role of the immune response against worms, with an emphasis on the Th2 response, which is a hallmark of helminth infections. We characterize non-immune cells (enteric tuft cells-ETCs) responsible for detecting parasites, as well as the role of hematopoietic-derived cells (macrophages, basophils, eosinophils, neutrophils, innate lymphoid cells group 2-ILC2s, mast cells, T cells, and B cells) in initiating and sustaining the immune response, as well as the functions they play in granulomas. The aim of this paper is to review the existing knowledge regarding the immune response against helminths, to attempt to decipher the interactions between cells engaged in the response, and to indicate the gaps in the current knowledge.

Emerging Therapeutic Options for Refractory Pulmonary Sarcoidosis: The Evidence and Proposed Mechanisms of Action

Sarcoidosis is a systemic disease with heterogenous clinical phenotypes characterized by non-necrotizing granuloma formation in affected organs. Most disease either remits spontaneously or responds to corticosteroids and second-line disease-modifying therapies. These medications are associated with numerous toxicities that can significantly impact patient quality-of-life and often limit their long-term use. Additionally, a minority of patients experience chronic, progressive disease that proves refractory to standard treatments. To date, there are limited data to guide the selection of alternative third-line medications for these patients. This review will outline the pathobiological rationale behind current and emerging therapeutic agents for refractory or drug-intolerant sarcoidosis and summarize the existing clinical evidence in support of their use.

Granulomas in bone marrow biopsies: clinicopathological significance and new perspectives

Bone marrow granulomas in trephine biopsies are a rare and usually incidental finding. Possible causes include infectious (especially tuberculous and rarer non-tuberculous mycobacteria, but also many other bacterial, viral, fungal and parasitic agents) and non-infectious causes (especially medications, autoimmune disease, sarcoidosis, haematological and non-haematological malignancy). Necrotising granulomas are generally suggestive of an infectious aetiology (tuberculosis being the most common), whereas fibrin ring granulomas are associated with Q-fever and Epstein Barr Virus, although exceptions are possible. Every case suspicious for infectious aetiology should undergo further analysis like special staining (Ziehl-Neelsen for acid-fast rods) or molecular studies. The histomorphology should always be clinically correlated. In cases in which no infectious cause can be identified, untargeted metagenomics may represent a valid diagnostic tool that may become standard in the near future for bone marrow diagnostics. In this review, we have analysed the published data from 1956 up to today, and we report aspects of epidemiology, aetiology, diagnostic algorithms, differential diagnosis and the role of metagenomics in bone marrow biopsies with granulomas.

Disseminated Miliary and Intestinal Tuberculosis Mimicking Inflammatory Bowel Disease

The hematogenous dissemination of Mycobacterium tuberculosis (M. tb) is commonly via the pulmonary system. Less commonly, ingestion of M. tb can lead to primary intestinal tuberculosis (TB), often misdiagnosed as inflammatory bowel disease (IBD). In extremely rare cases, the dissemination can involve cardiac infiltration/tuberculoma. One such case involves a 21-year-old man from Guatemala who spoke a rare dialect of Spanish with nonspecific complaints and an abdominal CT scan showing terminal ileum thickening suggestive of Crohn's disease (CD). A colonoscopy revealed ileitis and tissue biopsy showed granulomatous inflammation with a positive acid-fast bacillus (AFB) stain and positive blood cultures isolated for TB. Chest CT angiography (CTA) also revealed miliary nodules and a right atrial mass was confirmed with cardiac MRI. Viral serology revealed chronic hepatitis B virus (HBV) co-infection, but the patient was HIV-negative. Anti-tubercular therapy (ATT) with rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE), in addition to tenofovir, was initiated, followed by a complicated hospital stay including rifampin-induced bone marrow suppression. Ultimately, he was discharged on isoniazid, pyrazinamide, ethambutol, levofloxacin, and entecavir. Intestinal TB can be misdiagnosed as IBD with the administration of steroids, potentially worsening infection. A systemic approach to clinical investigation with a thorough history using medical translators can lead to early diagnosis and treatment of intestinal and disseminated TB.

Post-COVID-19 Granulomatous Inflammation in the Lung, Distinct From Sarcoidosis: A Report of Two Cases

This report describes two cases of granulomatous lung inflammation following coronavirus disease 2019 (COVID-19), presenting as a sarcoidosis-like reaction with granuloma formation in airspaces and interstitium. Clinical and pathological findings in both cases were similar to but still distinct from sarcoidosis. In the first case, the chest CT of a 55-year-old male with a history of polymerase chain reaction (PCR)-confirmed COVID-19 showed well-defined multiple nodules in the bilateral lung fields. He underwent video-assisted thoracic surgery for diagnostic purposes. The pathological specimen showed loose non-caseous granulomas with mild lymphoplasmacytic infiltration and early fibroblastic proliferation in alveolar spaces. In the second case, a 68-year-old male, who presented with consolidation in the anterior segment of the right upper lobe, underwent bronchoscopy and transbronchial lung biopsy showed non-caseous granulomas with mild lymphoplasmacytic infiltration in the peribronchiolar interstitium. The opacities improved spontaneously in both cases. Further studies are needed to determine whether COVID-19 could cause granulomatous lung inflammation distinct from sarcoidosis.