The role of pyroptosis in incomplete immune reconstitution among people living with HIV：Potential therapeutic targets

Globally, HIV infection causes significant morbidity and mortality, and is a major public health problem. Despite the fact that widespread use of antiretroviral therapy (ART) has substantially altered the natural history of HIV infection from originally being a universally lethal disease to now being a chronic medical condition for those taking appropriate treatment, approximately 10-40% of people living with HIV (PLWH) who take effective ART and maintain long-term viral suppression fail to achieve normalization of CD4 + T-cell counts. This phenomenon is referred to as incomplete immune reconstitution or immunological non-response. Although the precise mechanisms underlying this outcome have not been elucidated, recent evidence indicates that excessive pyroptosis may play a crucial role in the development of incomplete immune reconstitution. Pyroptosis is characterized by the formation of pores in the cell membrane, cell rupture, and secretion of intracellular contents and pro-inflammatory cytokines, including IL-1β and IL-18. This excessive inflammation-induced programmed cell death leads to a massive loss of CD4 + T-cells, and inflammatory consequences that may promote and sustain incomplete immune reconstitution. Herein, we review the possible pathways activated in HIV infection by inflammasomes that act as switches of pyroptosis, and the role of pyroptosis in HIV, as well as the relevance of CD4 + T-cells in incomplete immune reconstitution. We also highlight the possible mechanisms of pyroptosis involved in incomplete immune reconstitution, thus paving the way for the development of potential targets for the treatment of incomplete immune reconstitution.

Splenic infarction due to Mycobacterium avium complex infection in an HIV-infected patient with immune reconstitution failure: a case report

Splenic infarction is extremely rare in human immunodeficiency virus-infected populations. We report a rare case of splenic infarction involving Mycobacterium avium complex infection in a patient with acquired immune deficiency syndrome with immune reconstitution failure. A young man was initially admitted with cryptococcus meningitis and found to be infected with human immunodeficiency virus. He had anti-cryptococcosis treatment performed in combination with placement of an Ommaya capsule because of persistent intracranial hypertension, and first-line therapy followed by second-line anti-retroviral therapy were performed. Although there was an absence of immune reconstitution, the patient refused to take prophylactic sulfamethoxazole/trimethoprim, isoniazid, and clarithromycin continuously because of gastrointestinal intolerance. Pneumocystis pneumonia then developed. Finally, the patient developed a fever again accompanied by abdominal pain and splenic infarction. M. avium complex infection was verified by a metagenomic next-generation sequencing test using a whole blood sample. M. avium complex infection should be considered as an etiology of splenic infarction in human immunodeficiency virus-infected patients with an extremely low CD₄⁺T-cell count.

Upregulation of CD4+T-Cell Derived MiR-223 in The Relapsing Phase of Multiple Sclerosis Patients

Objective

MicroRNAs (miRNA) are a class of non-coding RNAs which play key roles in post-transcriptional gene regulation. Previous studies indicate that miRNAs are dysregulated in patients with multiple sclerosis (MS). Th17 and regulatory T (Treg) cells are two subsets of CD4+T-cells which have critical functions in the onset and progression of MS. The current study seeks to distinguish fluctuations in expression of CD4+T-cell derived miR-223 during the relapsing-remitting (RR) phase of MS (RR-MS), as well as the expressions of Th17 and Treg cell markers.

Materials and Methods

This experimental study used real-time quantitative polymerase chain reaction (qRT-PCR) to evaluate CD4+ T cell derived miR-223 expression patterns in patients that experienced either of the RR-MS phases (n=40) compared to healthy controls (n=12), along with RNA markers for Th17 and Treg cells. We conducted flow cytometry analyses of forkhead box P3 (FOXP3) and RAR-related orphan receptor γt (RORγt) in CD4+T-cells. Putative and validated targets of miR-223 were investigated in the miRWalk and miRTarBase databases, respectively.

Results

miR-223 significantly upregulated in CD4+T-cells during the relapsing phase of RR-MS compared to the remitting phase (P=0.000) and healthy individuals (P=0.036). Expression of RORγt, a master transcription factor of Th17, upregulated in the relapsing phase, whereas FOXP3 upregulated in the remitting phase. Additionally, potential targets of miR-223, STAT1, FORKHEAD BOX O (FOXO1) and FOXO3 were predicted by in silico studies.

Conclusion

miR-223 may have a potential role in MS progression. Therefore, suppression of miR-223 can be proposed as an appropriate approach to control progression of the relapsing phase of MS.

Inflammation and bone destruction in arthritis: synergistic activity of immune and mesenchymal cells in joints

Rheumatoid arthritis (RA) is an immune-mediated disease of the joints that is characterized by chronic inflammation and synovial hyperplasia that eventually lead to cartilage and bone destruction. Synovial fibroblasts are mesenchymal cells recognized as a key cell population in RA due to their hyperproliferative and hypersensitive properties in the inflammatory milieu and hyperproduction of both inflammatory cytokines and matrix-degrading enzymes. On the immune cell side, a wealth of evidence has shown that CD4⁺T-cells, especially IL-17 producing helper T (Th17) cells, play a prominent role, particularly in the initiation of systemic immune response in RA. However, it is still unclear how the local chronic inflammation in the joint is elicited by a systemic immune response. Recent studies have shed light on the importance of the interaction between immune and mesenchymal cells in joints including synovial fibroblasts. In particular, mesenchymal cells contribute to the Th17-mediated chronic inflammation in RA by promoting the migration of Th17 cells to the inflamed site and then the homeostatic proliferation and concomitant increase in IL-17 production. In addition, recent progress in osteoimmunology has provided new insight into the pathogenesis of the bone destruction which takes place in RA. Th17-related cytokines have been shown to enhance osteoclastogenesis, mainly via synovial fibroblasts. Thus, mesenchymal cells are a determinant of the development of RA that links the systemic immune response and the local disorder in the joints. In addition, the interaction of immune and mesenchymal cells plays a key role in both the chronic inflammation and bone destruction seen in RA. Elucidation of the precise events involved in this interaction will lead to a better understanding of the mechanisms by which chronic inflammation and bone destruction in joint results from a systemic immune response, and also will help provide a molecular basis for novel therapeutic strategies to treat RA.