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Glomerulonephritis (GN) is an important cause of renal inflammation resulting from kidney‐targeted adaptive and innate immune responses and consequent glomerular damage. Given the lack of autoantibodies, immune complexes, or the infiltrating immune cells in some forms of GN, for example, focal segmental glomerulosclerosis and minimal change disease, along with paraneoplastic syndrome and a special form of renal involvement in some viral infections, the likeliest causative scenario would be secreted factors, mainly cytokine(s). Since cytokines can modulate the inflammatory mechanisms, severity, and clinical outcomes of GN, it is rational to consider the umbrella term of cytokine GN as a new outlook to reclassify a group of previously known GN. We focus here, particularly, on cytokines that have the central "canonical effect" in the development of GN. [ABSTRACT FROM AUTHOR]

Idiopathic multicentric Castleman disease (iMCD) is a rare and life‐threatening haematologic disorder involving polyclonal lymphoproliferation and organ dysfunction due to excessive cytokine production, including interleukin‐6 (IL‐6). Clinical trial and real‐world data demonstrate that IL‐6 inhibition is effective in 34–50% of patients. mTOR, which functions through mTORC1 and mTORC2, is a recently discovered therapeutic target. The mTOR inhibitor sirolimus, which preferentially inhibits mTORC1, has led to sustained remission in a small cohort of anti‐IL‐6‐refractory iMCD patients with thrombocytopenia, anasarca, fever, renal dysfunction and organomegaly (iMCD‐TAFRO). However, sirolimus has not shown uniform effect, potentially due to its limited mTORC2 inhibition. To investigate mTORC2 activation in iMCD, we quantified the mTORC2 effector protein pNDRG1 by immunohistochemistry of lymph node tissue from six iMCD‐TAFRO and eight iMCD patients who do not meet TAFRO criteria (iMCD‐not‐otherwise‐specified; iMCD‐NOS). mTORC2 activation was increased in all regions of iMCD‐TAFRO lymph nodes and the interfollicular space of iMCD‐NOS compared with control tissue. Immunohistochemistry also revealed increased pNDRG1 expression in iMCD‐TAFRO germinal centres compared with autoimmune lymphoproliferative syndrome (ALPS), an mTOR‐driven, sirolimus‐responsive lymphoproliferative disorder, and comparable staining between iMCD‐NOS and ALPS. These results suggest increased mTORC2 activity in iMCD and that dual mTORC1/mTORC2 inhibitors may be a rational therapeutic approach. [ABSTRACT FROM AUTHOR]

Keywords: Castleman disease; interleukins; POEMS; KSHV/HHV8; HIV; TAFRO EN Castleman disease interleukins POEMS KSHV/HHV8 HIV TAFRO 328 337 10 11/01/21 20211101 NES 211101 Methodology This "Good Practice Paper" was compiled according to the British Society for Haematology (BSH) process at (http://www.b-s-h.org.uk/guidelines). Despite the success of IL-6-signalling blockade, there remains a significant unmet clinical need not only for patients who are intolerant of anti-IL-6 therapy, but also for a reliable disease-modifying therapy.50 Tocilizumab is a monoclonal antibody that antagonises the IL-6 receptor (IL-6R) to block signal transduction.57 Tocilizumab is licensed in Japan, but not in the UK, for the treatment of iMCD-TAFRO. Survival rates for MCD are not clear given changes in in diagnostic criteria, reporting and therapy.7 Nevertheless, the 5-year OS rate for MCD have been estimated at ˜65%.4 Human herpesvirus 8-associated MCD (HHV8-MCD) A proportion of cases of MCD have been attributed to infection with HHV8. The choice of therapy in MCD depends on the presentation of the patient as well as identification of drivers of disease: HHV8-MCD, POEMS-MCD, iMCD (NOS and TAFRO). [Extracted from the article]